Description of Organization and Business Operations	3 Months Ended	12 Months Ended
Mar. 31, 2025	Dec. 31, 2024
Description of Organization and Business Operations [Abstract]
DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS	NOTE 1. DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS Helix Acquisition Corp. II (the “Company”) is a blank check company incorporated as a Cayman Islands exempted company on June 15, 2021. The Company was incorporated for the purpose of effecting a merger, share exchange, asset acquisition, share purchase, reorganization or similar business combination with one or more businesses or entities (a “Business Combination”). The Company has one subsidiary, Helix II Merger Sub Inc., a Delaware corporation, a direct wholly owned subsidiary of the Company incorporated on February 26, 2025. As of March 31, 2025, the subsidiary had no activity. The Company is not limited to a particular industry or sector for purposes of consummating a Business Combination but intends to focus on healthcare and healthcare related industries. The Company is an early stage and emerging growth company and, as such, the Company is subject to all of the risks associated with early stage and emerging growth companies. As of March 31, 2025, the Company had not commenced any operations. All activity for the period from June 15, 2021 (inception) through March 31, 2025 relates to the Company’s formation, the initial public offering (“Initial Public Offering”), which is described below, and subsequent to the Initial Public Offering, identifying a target company for a Business Combination and negotiating and attempting to complete the proposed BBOT Business Combination (defined below). The Company does not expect to generate any operating revenues until after the completion of a Business Combination, at the earliest. The Company generates non-operating income in the form of interest income from the proceeds derived from the Initial Public Offering. The Company has selected December 31 as its fiscal year end. The registration statement for the Company’s Initial Public Offering was declared effective on February 8, 2024. On February 13, 2024, the Company consummated the Initial Public Offering of 18,400,000 Class A ordinary shares (the “Public Shares”), which includes the full exercise by the underwriter of its over-allotment option in the amount of 2,400,000 Public Shares, at $10.00 per Public Share, generating gross proceeds of $184,000,000, which is discussed in Note 3. Simultaneously with the closing of the Initial Public Offering, the Company consummated the sale of 509,000 Class A ordinary shares (the “Private Placement Shares”) to Helix Holdings II, LLC (the “Sponsor”) at a price of $10.00 per Private Placement Share, or $5,090,000 in the aggregate, which is described in Note 4. Transaction costs amounted to $8,180,834, consisting of $1,840,000 of upfront cash underwriting fee, $5,520,000 of deferred underwriting fee (see additional discussion on Note 6), and $820,834 of other offering costs. The Company’s management has broad discretion with respect to the specific application of the net proceeds of the Initial Public Offering and the sale of the Private Placement Shares, although substantially all of the net proceeds are intended to be applied generally toward consummating a Business Combination. The rules of Nasdaq require that the Company must complete one or more Business Combinations having an aggregate fair market value of at least 80% of the value of the assets held in the Trust Account (as defined below) (excluding the deferred underwriting commissions and taxes payable on the interest earned on the Trust Account) at the time of the agreement to enter into the initial Business Combination. The Company will only complete a Business Combination if the post transaction company owns or acquires 50% or more of the issued and outstanding voting securities of the target or otherwise acquires a controlling interest in the target business sufficient for it not to be required to register as an investment company under the Investment Company Act of 1940, as amended (the “Investment Company Act”). Following the closing of the Initial Public Offering, on February 13, 2024, an amount of $184,000,000 ($10.00 per Public Share) from the net proceeds of the sale of the Public Shares and the sale of the Private Placement Shares, after deducting $1,840,000 in underwriting discounts and commissions paid upon the closing of the Initial Public Offering and an aggregate of $3,250,000 to pay fees and expenses in connection with the closing of the Initial Public Offering and for working capital following the closing, was placed in the trust account (“Trust Account”), and either held in cash, deposited into an interest bearing or non-interest bearing bank demand deposit account at a U.S. chartered commercial bank with consolidated assets of $100 billion or more, or invested in U.S. government securities within the meaning of Section 2(a)(16) of the Investment Company Act having a maturity of 185 days or less or in money market funds meeting certain conditions under Rule 2a-7 under the Investment Company Act, which invest only in direct U.S. government treasury obligations, as determined by the Company, until the earliest of (i) the completion of a Business Combination and (ii) the distribution of the funds in the Trust Account to the Company’s shareholders, as described below. The Company will provide the holders of the Public Shares (the “Public Shareholders”) with the opportunity to redeem all or a portion of their Public Shares upon the completion of the Business Combination, either (i) in connection with a general meeting called to approve the Business Combination or (ii) without a shareholder vote by means of a tender offer. The decision as to whether the Company will seek shareholder approval of a Business Combination or conduct a tender offer will be made by the Company, solely in its discretion. The Public Shareholders will be entitled to redeem their Public Shares, equal to the aggregate amount then on deposit in the Trust Account, calculated as of two business days prior to the consummation of the Business Combination (initially anticipated to be $10.00 per Public Share), including interest (less taxes paid or payable), divided by the number of then issued and outstanding Public Shares, subject to certain limitations as described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024, as filed with the SEC on March 11, 2025. The per-share amount to be distributed to the Public Shareholders who properly redeem their Public Shares will not be reduced by the deferred underwriting commissions the Company will pay to the underwriter (as discussed in Note 6). The Class A ordinary shares will be recorded at redemption value and classified as temporary equity upon the completion of the Initial Public Offering, in accordance with Accounting Standards Codification (“ASC”) Topic 480, “Distinguishing Liabilities from Equity.” Notwithstanding the foregoing, if the Company seeks shareholder approval of the Business Combination and the Company does not conduct redemptions pursuant to the tender offer rules, a Public Shareholder, together with any affiliate of such shareholder or any other person with whom such shareholder is acting in concert or as a “group” (as defined under Section 13 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”)), will be restricted from redeeming its shares with respect to more than an aggregate of 20% of the Public Shares without the Company’s prior written consent. The Sponsor has agreed (a) to waive its redemption rights with respect to any Founder Shares (as defined below), Private Placement Shares and Public Shares held by it in connection with the completion of a Business Combination and (b) not to propose an amendment to the Amended and Restated Memorandum and Articles of Association (i) to modify the substance or timing of the Company’s obligation to allow redemption in connection with the Company’s initial Business Combination or to redeem 100% of the Public Shares if the Company does not complete a Business Combination within the Completion Window (as defined below) or (ii) with respect to any other provision relating to shareholders’ rights or pre-initial Business Combination activity, unless the Company provides the Public Shareholders with the opportunity to redeem their Public Shares upon approval of any such amendment at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest earned on the Trust Account (less taxes paid or payable), divided by the number of then issued and outstanding Public Shares. The Company will have until (i) the period ending on the date that is 24 months from the closing of the Initial Public Offering, or such earlier liquidation as the Company’s board of directors may approve, in which the Company must complete an initial Business Combination or (ii) such other time period in which the Company must complete an initial Business Combination pursuant to an amendment to the Company’s Amended and Restated Memorandum and Articles of Association (the “Completion Window”). However, if the Company has not completed a Business Combination within the Completion Window, the Company will as promptly as reasonably possible but not more than ten business days thereafter, redeem 100% of the Public Shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest earned on the funds held in the Trust Account (less taxes paid or payable and up to $100,000 of interest to pay dissolution expenses), divided by the number of then issued and outstanding Public Shares, which redemption will constitute full and complete payment for the Public Shares and completely extinguish the rights of the Public Shareholders as shareholders (including the right to receive further liquidation or other distributions, if any), subject to the Company’s obligations under Cayman Islands law to provide for claims of creditors and subject to the other requirements of applicable law. The Sponsor has agreed to waive its rights to liquidating distributions from the Trust Account with respect to the Founder Shares and Private Placement Shares if the Company fails to complete a Business Combination within the Completion Window. However, the Public Shares acquired by affiliates of the Sponsor in the Initial Public Offering, and any other Public Shares that the Sponsor or its affiliates may acquire thereafter, will be entitled to liquidating distributions from the Trust Account if the Company fails to complete a Business Combination within the Completion Window. The underwriter has agreed to waive its rights to its deferred underwriting commission (see Note 6) held in the Trust Account in the event the Company does not complete a Business Combination within the Completion Window, and in such event, such amounts will be included with the other funds held in the Trust Account that will be available to fund the redemption of the Public Shares. In the event of such distribution, it is possible that the per share value of the assets remaining available for distribution will be less than the Initial Public Offering price per Share ($10.00). In order to protect the amounts held in the Trust Account, the Sponsor has agreed that it will be liable to the Company if and to the extent any claims by a third party (other than the Company’s independent registered public accounting firm) for services rendered or products sold to the Company, or a prospective target business with which the Company has discussed entering into a transaction agreement, reduce the amount of funds in the Trust Account to below the lesser of (1) $10.00 per Public Share (2) the actual amount per Public Share held in the Trust Account as of the date of the liquidation of the Trust Account, if less than $10.00 per Public Share, due to reductions in the value of trust assets, less taxes paid or payable and up to $100,000 of interest to pay dissolution expenses, provided that this liability will not apply to any claims by a third party who executed a waiver of any and all rights to seek access to the Trust Account and as to any claims under the Company’s indemnity of the underwriter of the Initial Public Offering against certain liabilities, including liabilities under the Securities Act of 1933, as amended (the “Securities Act”). In the event that an executed waiver is deemed to be unenforceable against a third party, the Sponsor will not be responsible to the extent of any liability for such third-party claims. The Company will seek to reduce the possibility that the Sponsor will have to indemnify the Trust Account due to claims of creditors by endeavoring to have all vendors, service providers (other than the Company’s independent registered public accounting firm), prospective target businesses or other entities with which the Company does business, execute agreements with the Company waiving any right, title, interest or claim of any kind in or to monies held in the Trust Account. Proposed Business Combination with TheRas, Inc. (dba BridgeBio Oncology Therapeutics) On February 28, 2025, the Company entered into a business combination agreement (the “BBOT Business Combination Agreement”, and the transactions contemplated thereby, including the Domestication and Merger, each as defined below, the “BBOT Business Combination”) with TheRas, Inc., a Delaware corporation (doing business as BridgeBio Oncology Therapeutics, “BBOT”) and Helix II Merger Sub, Inc., a Delaware corporation and a wholly-owned subsidiary of the Company (“Merger Sub”), pursuant to which, among other things and subject to the terms and conditions contained in the BBOT Business Combination Agreement (i) the Company will de-register in the Cayman Islands and transfer by way of continuation out of the Cayman Islands and into the State of Delaware so as to migrate to and domesticate as a Delaware corporation (the “Domestication”), and (ii) following the Domestication, Merger Sub will be merged with and into BBOT, as a result of which BBOT will be the surviving company and a wholly-owned subsidiary of the Company (the “Merger”). Consummation of the transactions contemplated by the BBOT Business Combination Agreement are subject to customary conditions of the respective parties, including the approval of the BBOT Business Combination Agreement, the Business Combination and certain other actions related thereto by the Company’s shareholders, and the availability of a minimum amount of aggregate transaction proceeds. For more information, see Note 6. Going Concern Consideration As of March 31, 2025, the Company had cash of $963,135 and working capital deficit of $631,351. Until the consummation of an initial Business Combination, the Company has been and will be using the funds held outside the Trust Account for identifying and evaluating target businesses, performing due diligence on prospective target businesses, paying for travel expenditures, reviewing corporate documents and material agreements of prospective target businesses, and structuring, negotiating and completing an initial Business Combination. In order to finance transaction costs in connection with a Business Combination, the Sponsor or an affiliate of the Sponsor, or certain of the Company’s officers and directors may, but are not obligated to, loan the Company funds as may be required (“Working Capital Loans”). If the Company completes a Business Combination, the Company would repay the Working Capital Loans out of the proceeds of the Trust Account released to the Company. Otherwise, the Working Capital Loans would be repaid only out of funds held outside the Trust Account. In the event that a Business Combination does not close, the Company may use a portion of proceeds held outside the Trust Account to repay the Working Capital Loans, but no proceeds held in the Trust Account would be used to repay the Working Capital Loans. Except for the foregoing, the terms of such Working Capital Loans, if any, have not been determined and no written agreements exist with respect to such loans. If the Company completes a Business Combination, the Working Capital Loans would either be repaid upon consummation of a Business Combination, without interest, or, at the lender’s discretion, up to $1,500,000 of such Working Capital Loans may be convertible into private placement shares of the post-Business Combination entity at a price of $10.00 per share. The shares would be identical to the Private Placement Shares. As of March 31, 2025 and December 31, 2024, the Company had no outstanding borrowings under Working Capital Loans. In connection with the Company’s assessment of going concern considerations in accordance with FASB Accounting Standards Update 2014-15, “Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern,” management has determined that the Company currently lacks the liquidity it needs to sustain operations for a reasonable period of time, which is considered to be at least one year from the date that the financial statements are issued as it expects to continue to incur significant costs in pursuit of its acquisition plans. In addition, management has determined that if the Company is unable to complete an initial Business Combination by February 14, 2026, then the Company will cease all operations except for the purpose of liquidating. These conditions raise substantial doubt about the Company’s ability to continue as a going concern. Management plans to consummate an initial Business Combination prior to the mandatory liquidation date. No adjustments have been made to the carrying amounts of assets or liabilities should the Company be required to liquidate after February 14, 2026.	NOTE 1. ORGANIZATION AND PLAN OF BUSINESS OPERATIONS Helix Acquisition Corp. II (the “Company”) is a blank check company incorporated as a Cayman Islands exempted company on June 15, 2021. The Company was incorporated for the purpose of effecting a merger, share exchange, asset acquisition, share purchase, reorganization or similar business combination with one or more businesses or entities (a “Business Combination”). The Company is not limited to a particular industry or sector for purposes of consummating a Business Combination but intends to focus on healthcare and healthcare related industries. The Company is an early stage and emerging growth company and, as such, the Company is subject to all of the risks associated with early stage and emerging growth companies. As of December 31, 2024, the Company had not commenced any operations. All activity for the period from June 15, 2021 (inception) through December 31, 2024 relates to the Company’s formation, the initial public offering (“Initial Public Offering”), which is described below, and subsequent to the Initial Public Offering, identifying a target company for a Business Combination. The Company will not generate any operating revenues until after the completion of a Business Combination, at the earliest. The Company will generate non-operating income in the form of interest income from the proceeds derived from the Initial Public Offering. The Company has selected December 31 as its fiscal year end. The registration statement for the Company’s Initial Public Offering was declared effective on February 8, 2024. On February 13, 2024, the Company consummated the Initial Public Offering of 18,400,000 Class A ordinary shares (the “Public Shares”), which includes the full exercise by the underwriter of its over-allotment option in the amount of 2,400,000 Public Shares, at $10.00 per Public Share, generating gross proceeds of $184,000,000, which is discussed in Note 3. Simultaneously with the closing of the Initial Public Offering, the Company consummated the sale of 509,000 Class A ordinary shares (the “Private Placement Shares”) to Helix Holdings II, LLC (the “Sponsor”) at a price of $10.00 per Private Placement Share, or $5,090,000 in the aggregate, which is described in Note 4. Transaction costs amounted to $8,180,834, consisting of $1,840,000 of upfront cash underwriting fee, $5,520,000 of deferred underwriting fee (see additional discussion on Note 6), and $820,834 of other offering costs. The Company’s management has broad discretion with respect to the specific application of the net proceeds of the Initial Public Offering and the sale of the Private Placement Shares, although substantially all of the net proceeds are intended to be applied generally toward consummating a Business Combination. The rules of Nasdaq require that the Company must complete one or more Business Combinations having an aggregate fair market value of at least 80% of the value of the assets held in the Trust Account (as defined below) (excluding the deferred underwriting commissions and taxes payable on the interest earned on the Trust Account) at the time of the agreement to enter into the initial Business Combination. The Company anticipates structuring the initial Business Combination so that the post transaction company in which the Public Shareholders (as defined below) own shares will own or acquire 100% of the equity interests or assets of the target business or businesses. The Company may, however, structure the initial Business Combination such that the post transaction company owns or acquires less than 100% of such interests or assets of the target business in order to meet certain objectives of the target management team or shareholders or for other reasons, but the Company will only complete such Business Combination if the post transaction company owns or acquires 50% or more of the issued and outstanding voting securities of the target or otherwise acquires a controlling interest in the target business sufficient for it not to be required to register as an investment company under the Investment Company Act of 1940, as amended (the “Investment Company Act”). Following the closing of the Initial Public Offering, on February 13, 2024, an amount of $184,000,000 ($10.00 per Share) from the net proceeds of the sale of the Public Shares and the sale of the Private Placement Shares, after deducting $1,840,000 in underwriting discounts and commissions paid upon the closing of the Initial Public Offering and an aggregate of $3,250,000 to pay fees and expenses in connection with the closing of the Initial Public Offering and for working capital following the closing, was placed in the trust account (“Trust Account”), and either held in cash, deposited into an interest bearing or non-interest bearing bank demand deposit account at a U.S. chartered commercial bank with consolidated assets of $100 billion or more, or invested in U.S. government securities within the meaning of Section 2(a)(16) of the Investment Company Act having a maturity of 185 days or less or in money market funds meeting certain conditions under Rule 2a-7 under the Investment Company Act, which invest only in direct U.S. government treasury obligations, as determined by the Company, until the earliest of (i) the completion of a Business Combination and (ii) the distribution of the funds in the Trust Account to the Company’s shareholders, as described below. The Company will provide the holders of the Public Shares (the “Public Shareholders”) with the opportunity to redeem all or a portion of their Public Shares upon the completion of the Business Combination, either (i) in connection with a general meeting called to approve the Business Combination or (ii) without a shareholder vote by means of a tender offer. The decision as to whether the Company will seek shareholder approval of a Business Combination or conduct a tender offer will be made by the Company, solely in its discretion. The Public Shareholders will be entitled to redeem their Public Shares, equal to the aggregate amount then on deposit in the Trust Account, calculated as of two business days prior to the consummation of the Business Combination (initially anticipated to be $10.00 per Public Share), including interest (less taxes paid or payable), divided by the number of then issued and outstanding Public Shares, subject to certain limitations as described in the Annual Report. The per-share amount to be distributed to the Public Shareholders who properly redeem their Public Shares will not be reduced by the deferred underwriting commissions the Company will pay to the underwriter (as discussed in Note 6). The Class A ordinary shares will be recorded at redemption value and classified as temporary equity upon the completion of the Initial Public Offering, in accordance with Accounting Standards Codification (“ASC”) Topic 480, “Distinguishing Liabilities from Equity.” Notwithstanding the foregoing, if the Company seeks shareholder approval of the Business Combination and the Company does not conduct redemptions pursuant to the tender offer rules, a Public Shareholder, together with any affiliate of such shareholder or any other person with whom such shareholder is acting in concert or as a “group” (as defined under Section 13 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”)), will be restricted from redeeming its shares with respect to more than an aggregate of 20% of the Public Shares without the Company’s prior written consent. The Sponsor has agreed (a) to waive its redemption rights with respect to any Founder Shares (as defined below), Private Placement Shares and Public Shares held by it in connection with the completion of a Business Combination and (b) not to propose an amendment to the Amended and Restated Memorandum and Articles of Association (i) to modify the substance or timing of the Company’s obligation to allow redemption in connection with the Company’s initial Business Combination or to redeem 100% of the Public Shares if the Company does not complete a Business Combination within the Completion Window (as defined below) or (ii) with respect to any other provision relating to shareholders’ rights or pre-initial Business Combination activity, unless the Company provides the Public Shareholders with the opportunity to redeem their Public Shares upon approval of any such amendment at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest earned on the Trust Account (less taxes paid or payable), divided by the number of then issued and outstanding Public Shares. The Company will have until (i) the period ending on the date that is 24 months from the closing of the Initial Public Offering, or such earlier liquidation as the Company’s board of directors may approve, in which the Company must complete an initial Business Combination or (ii) such other time period in which the Company must complete an initial Business Combination pursuant to an amendment to the Company’s Amended and Restated Memorandum and Articles of Association (the “Completion Window”). However, if the Company has not completed a Business Combination within the Completion Window, the Company will as promptly as reasonably possible but not more than ten business days thereafter, redeem 100% of the Public Shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest earned on the funds held in the Trust Account (less taxes paid or payable and up to $100,000 of interest to pay dissolution expenses), divided by the number of then issued and outstanding Public Shares, which redemption will constitute full and complete payment for the Public Shares and completely extinguish the rights of the Public Shareholders as shareholders (including the right to receive further liquidation or other distributions, if any), subject to the Company’s obligations under Cayman Islands law to provide for claims of creditors and subject to the other requirements of applicable law. The Sponsor has agreed to waive its rights to liquidating distributions from the Trust Account with respect to the Founder Shares and Private Placement Shares if the Company fails to complete a Business Combination within the Completion Window. However, the Public Shares acquired by affiliates of the Sponsor in the Initial Public Offering, and any other Public Shares that the Sponsor or its affiliates may acquire thereafter, will be entitled to liquidating distributions from the Trust Account if the Company fails to complete a Business Combination within the Completion Window. The underwriter has agreed to waive its rights to its deferred underwriting commission (see Note 6) held in the Trust Account in the event the Company does not complete a Business Combination within the Completion Window, and in such event, such amounts will be included with the other funds held in the Trust Account that will be available to fund the redemption of the Public Shares. In the event of such distribution, it is possible that the per share value of the assets remaining available for distribution will be less than the Initial Public Offering price per Share ($10.00). In order to protect the amounts held in the Trust Account, the Sponsor has agreed that it will be liable to the Company if and to the extent any claims by a third party (other than the Company’s independent registered public accounting firm) for services rendered or products sold to the Company, or a prospective target business with which the Company has discussed entering into a transaction agreement, reduce the amount of funds in the Trust Account to below the lesser of (1) $10.00 per Public Share (2) the actual amount per Public Share held in the Trust Account as of the date of the liquidation of the Trust Account, if less than $10.00 per Public Share, due to reductions in the value of trust assets, less taxes paid or payable and up to $100,000 of interest to pay dissolution expenses, provided that this liability will not apply to any claims by a third party who executed a waiver of any and all rights to seek access to the Trust Account and as to any claims under the Company’s indemnity of the underwriter of the Initial Public Offering against certain liabilities, including liabilities under the Securities Act of 1933, as amended (the “Securities Act”). In the event that an executed waiver is deemed to be unenforceable against a third party, the Sponsor will not be responsible to the extent of any liability for such third-party claims. The Company will seek to reduce the possibility that the Sponsor will have to indemnify the Trust Account due to claims of creditors by endeavoring to have all vendors, service providers (other than the Company’s independent registered public accounting firm), prospective target businesses or other entities with which the Company does business, execute agreements with the Company waiving any right, title, interest or claim of any kind in or to monies held in the Trust Account. Going Concern Consideration As of December 31, 2024, the Company had cash of $1,697,777 and working capital of $1,762,262. Until the consummation of an Initial Business Combination, the Company will be using the funds held outside the Trust Account for identifying and evaluating target businesses, performing due diligence on prospective target businesses, paying for travel expenditures, reviewing corporate documents and material agreements of prospective target businesses, and structuring, negotiating and completing an Initial Business Combination. In order to finance transaction costs in connection with a Business Combination, the Sponsor or an affiliate of the Sponsor, or certain of the Company’s officers and directors may, but are not obligated to, loan the Company funds as may be required (“Working Capital Loans”). If the Company completes a Business Combination, the Company would repay the Working Capital Loans out of the proceeds of the Trust Account released to the Company. Otherwise, the Working Capital Loans would be repaid only out of funds held outside the Trust Account. In the event that a Business Combination does not close, the Company may use a portion of proceeds held outside the Trust Account to repay the Working Capital Loans, but no proceeds held in the Trust Account would be used to repay the Working Capital Loans. Except for the foregoing, the terms of such Working Capital Loans, if any, have not been determined and no written agreements exist with respect to such loans. The Working Capital Loans would either be repaid upon consummation of a Business Combination, without interest, or, at the lender’s discretion, up to $1,500,000 of such Working Capital Loans may be convertible into private placement shares of the post-Business Combination entity at a price of $10.00 per share. The shares would be identical to the Private Placement Shares. As of December 31, 2024 and 2023, the Company had no outstanding borrowings under the Working Capital Loans. In connection with the Company’s assessment of going concern considerations in accordance with FASB Accounting Standards Update 2014-15, “Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern,” management has determined that if the Company is unable to complete an Initial Business Combination by February 14, 2026, then the Company will cease all operations except for the purpose of liquidating. The date for mandatory liquidation and subsequent dissolution raises substantial doubt about the Company’s ability to continue as a going concern. Management plans to consummate an Initial Business Combination prior to the mandatory liquidation date. No adjustments have been made to the carrying amounts of assets or liabilities should the Company be required to liquidate after February 14, 2026.

Description of Organization and Business Operations

3 Months Ended

12 Months Ended

Mar. 31, 2025

Dec. 31, 2024

Description of Organization and Business Operations [Abstract]

DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS

NOTE 1. DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS

Helix Acquisition Corp. II (the “Company”) is a blank check company incorporated as a Cayman Islands exempted company on June 15, 2021. The Company was incorporated for the purpose of effecting a merger, share exchange, asset acquisition, share purchase, reorganization or similar business combination with one or more businesses or entities (a “Business Combination”).

The Company has one subsidiary, Helix II Merger Sub Inc., a Delaware corporation, a direct wholly owned subsidiary of the Company incorporated on February 26, 2025. As of March 31, 2025, the subsidiary had no activity.

The Company is not limited to a particular industry or sector for purposes of consummating a Business Combination but intends to focus on healthcare and healthcare related industries. The Company is an early stage and emerging growth company and, as such, the Company is subject to all of the risks associated with early stage and emerging growth companies.

As of March 31, 2025, the Company had not commenced any operations. All activity for the period from June 15, 2021 (inception) through March 31, 2025 relates to the Company’s formation, the initial public offering (“Initial Public Offering”), which is described below, and subsequent to the Initial Public Offering, identifying a target company for a Business Combination and negotiating and attempting to complete the proposed BBOT Business Combination (defined below). The Company does not expect to generate any operating revenues until after the completion of a Business Combination, at the earliest. The Company generates non-operating income in the form of interest income from the proceeds derived from the Initial Public Offering. The Company has selected December 31 as its fiscal year end.

The registration statement for the Company’s Initial Public Offering was declared effective on February 8, 2024. On February 13, 2024, the Company consummated the Initial Public Offering of 18,400,000 Class A ordinary shares (the “Public Shares”), which includes the full exercise by the underwriter of its over-allotment option in the amount of 2,400,000 Public Shares, at $10.00 per Public Share, generating gross proceeds of $184,000,000, which is discussed in Note 3. Simultaneously with the closing of the Initial Public Offering, the Company consummated the sale of 509,000 Class A ordinary shares (the “Private Placement Shares”) to Helix Holdings II, LLC (the “Sponsor”) at a price of $10.00 per Private Placement Share, or $5,090,000 in the aggregate, which is described in Note 4.

Transaction costs amounted to $8,180,834, consisting of $1,840,000 of upfront cash underwriting fee, $5,520,000 of deferred underwriting fee (see additional discussion on Note 6), and $820,834 of other offering costs.

Following the closing of the Initial Public Offering, on February 13, 2024, an amount of $184,000,000 ($10.00 per Public Share) from the net proceeds of the sale of the Public Shares and the sale of the Private Placement Shares, after deducting $1,840,000 in underwriting discounts and commissions paid upon the closing of the Initial Public Offering and an aggregate of $3,250,000 to pay fees and expenses in connection with the closing of the Initial Public Offering and for working capital following the closing, was placed in the trust account (“Trust Account”), and either held in cash, deposited into an interest bearing or non-interest bearing bank demand deposit account at a U.S. chartered commercial bank with consolidated assets of $100 billion or more, or invested in U.S. government securities within

the meaning of Section 2(a)(16) of the Investment Company Act having a maturity of 185 days or less or in money market funds meeting certain conditions under Rule 2a-7 under the Investment Company Act, which invest only in direct U.S. government treasury obligations, as determined by the Company, until the earliest of (i) the completion of a Business Combination and (ii) the distribution of the funds in the Trust Account to the Company’s shareholders, as described below.

The Company will provide the holders of the Public Shares (the “Public Shareholders”) with the opportunity to redeem all or a portion of their Public Shares upon the completion of the Business Combination, either (i) in connection with a general meeting called to approve the Business Combination or (ii) without a shareholder vote by means of a tender offer. The decision as to whether the Company will seek shareholder approval of a Business Combination or conduct a tender offer will be made by the Company, solely in its discretion. The Public Shareholders will be entitled to redeem their Public Shares, equal to the aggregate amount then on deposit in the Trust Account, calculated as of two business days prior to the consummation of the Business Combination (initially anticipated to be $10.00 per Public Share), including interest (less taxes paid or payable), divided by the number of then issued and outstanding Public Shares, subject to certain limitations as described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024, as filed with the SEC on March 11, 2025. The per-share amount to be distributed to the Public Shareholders who properly redeem their Public Shares will not be reduced by the deferred underwriting commissions the Company will pay to the underwriter (as discussed in Note 6). The Class A ordinary shares will be recorded at redemption value and classified as temporary equity upon the completion of the Initial Public Offering, in accordance with Accounting Standards Codification (“ASC”) Topic 480, “Distinguishing Liabilities from Equity.”

Notwithstanding the foregoing, if the Company seeks shareholder approval of the Business Combination and the Company does not conduct redemptions pursuant to the tender offer rules, a Public Shareholder, together with any affiliate of such shareholder or any other person with whom such shareholder is acting in concert or as a “group” (as defined under Section 13 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”)), will be restricted from redeeming its shares with respect to more than an aggregate of 20% of the Public Shares without the Company’s prior written consent.

The Sponsor has agreed (a) to waive its redemption rights with respect to any Founder Shares (as defined below), Private Placement Shares and Public Shares held by it in connection with the completion of a Business Combination and (b) not to propose an amendment to the Amended and Restated Memorandum and Articles of Association (i) to modify the substance or timing of the Company’s obligation to allow redemption in connection with the Company’s initial Business Combination or to redeem 100% of the Public Shares if the Company does not complete a Business Combination within the Completion Window (as defined below) or (ii) with respect to any other provision relating to shareholders’ rights or pre-initial Business Combination activity, unless the Company provides the Public Shareholders with the opportunity to redeem their Public Shares upon approval of any such amendment at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest earned on the Trust Account (less taxes paid or payable), divided by the number of then issued and outstanding Public Shares.

The Company will have until (i) the period ending on the date that is 24 months from the closing of the Initial Public Offering, or such earlier liquidation as the Company’s board of directors may approve, in which the Company must complete an initial Business Combination or (ii) such other time period in which the Company must complete an initial Business Combination pursuant to an amendment to the Company’s Amended and Restated Memorandum and Articles of Association (the “Completion Window”). However, if the Company has not completed a Business Combination within the Completion Window, the Company will as promptly as reasonably possible but not more than ten business days thereafter, redeem 100% of the Public Shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest earned on the funds held in the Trust Account (less taxes paid or payable and up to $100,000 of interest to pay dissolution expenses), divided by the number of then issued and outstanding Public Shares, which redemption will constitute full and complete payment for the

Public Shares and completely extinguish the rights of the Public Shareholders as shareholders (including the right to receive further liquidation or other distributions, if any), subject to the Company’s obligations under Cayman Islands law to provide for claims of creditors and subject to the other requirements of applicable law.

The Sponsor has agreed to waive its rights to liquidating distributions from the Trust Account with respect to the Founder Shares and Private Placement Shares if the Company fails to complete a Business Combination within the Completion Window. However, the Public Shares acquired by affiliates of the Sponsor in the Initial Public Offering, and any other Public Shares that the Sponsor or its affiliates may acquire thereafter, will be entitled to liquidating distributions from the Trust Account if the Company fails to complete a Business Combination within the Completion Window. The underwriter has agreed to waive its rights to its deferred underwriting commission (see Note 6) held in the Trust Account in the event the Company does not complete a Business Combination within the Completion Window, and in such event, such amounts will be included with the other funds held in the Trust Account that will be available to fund the redemption of the Public Shares. In the event of such distribution, it is possible that the per share value of the assets remaining available for distribution will be less than the Initial Public Offering price per Share ($10.00).

In order to protect the amounts held in the Trust Account, the Sponsor has agreed that it will be liable to the Company if and to the extent any claims by a third party (other than the Company’s independent registered public accounting firm) for services rendered or products sold to the Company, or a prospective target business with which the Company has discussed entering into a transaction agreement, reduce the amount of funds in the Trust Account to below the lesser of (1) $10.00 per Public Share (2) the actual amount per Public Share held in the Trust Account as of the date of the liquidation of the Trust Account, if less than $10.00 per Public Share, due to reductions in the value of trust assets, less taxes paid or payable and up to $100,000 of interest to pay dissolution expenses, provided that this liability will not apply to any claims by a third party who executed a waiver of any and all rights to seek access to the Trust Account and as to any claims under the Company’s indemnity of the underwriter of the Initial Public Offering against certain liabilities, including liabilities under the Securities Act of 1933, as amended (the “Securities Act”). In the event that an executed waiver is deemed to be unenforceable against a third party, the Sponsor will not be responsible to the extent of any liability for such third-party claims. The Company will seek to reduce the possibility that the Sponsor will have to indemnify the Trust Account due to claims of creditors by endeavoring to have all vendors, service providers (other than the Company’s independent registered public accounting firm), prospective target businesses or other entities with which the Company does business, execute agreements with the Company waiving any right, title, interest or claim of any kind in or to monies held in the Trust Account.

Proposed Business Combination with TheRas, Inc. (dba BridgeBio Oncology Therapeutics)

On February 28, 2025, the Company entered into a business combination agreement (the “BBOT Business Combination Agreement”, and the transactions contemplated thereby, including the Domestication and Merger, each as defined below, the “BBOT Business Combination”) with TheRas, Inc., a Delaware corporation (doing business as BridgeBio Oncology Therapeutics, “BBOT”) and Helix II Merger Sub, Inc., a Delaware corporation and a wholly-owned subsidiary of the Company (“Merger Sub”), pursuant to which, among other things and subject to the terms and conditions contained in the BBOT Business Combination Agreement (i) the Company will de-register in the Cayman Islands and transfer by way of continuation out of the Cayman Islands and into the State of Delaware so as to migrate to and domesticate as a Delaware corporation (the “Domestication”), and (ii) following the Domestication, Merger Sub will be merged with and into BBOT, as a result of which BBOT will be the surviving company and a wholly-owned subsidiary of the Company (the “Merger”). Consummation of the transactions contemplated by the BBOT Business Combination Agreement are subject to customary conditions of the respective parties, including the approval of the BBOT Business Combination Agreement, the Business Combination and certain other actions related thereto by the Company’s shareholders, and the availability of a minimum amount of aggregate transaction proceeds. For more information, see Note 6.

Going Concern Consideration

As of March 31, 2025, the Company had cash of $963,135 and working capital deficit of $631,351.

Until the consummation of an initial Business Combination, the Company has been and will be using the funds held outside the Trust Account for identifying and evaluating target businesses, performing due diligence on prospective target businesses, paying for travel expenditures, reviewing corporate documents and material agreements of prospective target businesses, and structuring, negotiating and completing an initial Business Combination.

In order to finance transaction costs in connection with a Business Combination, the Sponsor or an affiliate of the Sponsor, or certain of the Company’s officers and directors may, but are not obligated to, loan the Company funds as may be required (“Working Capital Loans”). If the Company completes a Business Combination, the Company would repay the Working Capital Loans out of the proceeds of the Trust Account released to the Company. Otherwise, the Working Capital Loans would be repaid only out of funds held outside the Trust Account. In the event that a Business Combination does not close, the Company may use a portion of proceeds held outside the Trust Account to repay the Working Capital Loans, but no proceeds held in the Trust Account would be used to repay the Working Capital Loans. Except for the foregoing, the terms of such Working Capital Loans, if any, have not been determined and no written agreements exist with respect to such loans. If the Company completes a Business Combination, the Working Capital Loans would either be repaid upon consummation of a Business Combination, without interest, or, at the lender’s discretion, up to $1,500,000 of such Working Capital Loans may be convertible into private placement shares of the post-Business Combination entity at a price of $10.00 per share. The shares would be identical to the Private Placement Shares. As of March 31, 2025 and December 31, 2024, the Company had no outstanding borrowings under Working Capital Loans.

In connection with the Company’s assessment of going concern considerations in accordance with FASB Accounting Standards Update 2014-15, “Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern,” management has determined that the Company currently lacks the liquidity it needs to sustain operations for a reasonable period of time, which is considered to be at least one year from the date that the financial statements are issued as it expects to continue to incur significant costs in pursuit of its acquisition plans. In addition, management has determined that if the Company is unable to complete an initial Business Combination by February 14, 2026, then the Company will cease all operations except for the purpose of liquidating. These conditions raise substantial doubt about the Company’s ability to continue as a going concern. Management plans to consummate an initial Business Combination prior to the mandatory liquidation date. No adjustments have been made to the carrying amounts of assets or liabilities should the Company be required to liquidate after February 14, 2026.

NOTE 1. ORGANIZATION AND PLAN OF BUSINESS OPERATIONS

As of December 31, 2024, the Company had not commenced any operations. All activity for the period from June 15, 2021 (inception) through December 31, 2024 relates to the Company’s formation, the initial public offering (“Initial Public Offering”), which is described below, and subsequent to the Initial Public Offering, identifying a target company for a Business Combination. The Company will not generate any operating revenues until after the completion of a Business Combination, at the earliest. The Company will generate non-operating income in the form of interest income from the proceeds derived from the Initial Public Offering. The Company has selected December 31 as its fiscal year end.

The Company’s management has broad discretion with respect to the specific application of the net proceeds of the Initial Public Offering and the sale of the Private Placement Shares, although substantially all of the net proceeds are intended to be applied generally toward consummating a Business Combination. The rules of Nasdaq require that the Company must complete one or more Business Combinations having an aggregate fair market value of at least 80% of the value of the assets held in the Trust Account (as defined below) (excluding the deferred underwriting commissions and taxes payable on the interest earned on the Trust Account) at the time of the agreement to enter into the initial Business Combination. The Company anticipates structuring the initial Business Combination so that the post transaction company in which the Public Shareholders (as defined below) own shares will own or acquire 100% of the equity interests or assets of the target business or businesses. The Company may, however, structure the initial Business Combination such that the post transaction company owns or acquires less than 100% of such interests or assets of the target business in order to meet certain objectives of the target management team or shareholders or for other reasons, but the Company will only complete such Business Combination if the post transaction company owns or acquires 50% or more of the issued and outstanding voting securities of the target or otherwise acquires a controlling interest in the target business sufficient for it not to be required to register as an investment company under the Investment Company Act of 1940, as amended (the “Investment Company Act”).

Following the closing of the Initial Public Offering, on February 13, 2024, an amount of $184,000,000 ($10.00 per Share) from the net proceeds of the sale of the Public Shares and the sale of the Private Placement Shares, after deducting $1,840,000 in underwriting discounts and commissions paid upon the closing of the Initial Public Offering and an aggregate of $3,250,000 to pay fees and expenses in connection with the closing of the Initial Public Offering and for working capital following the closing, was placed in the trust account (“Trust Account”), and either held in cash, deposited into an interest bearing or non-interest bearing bank demand deposit account at a U.S. chartered commercial bank with consolidated assets of $100 billion or more, or invested in U.S. government securities within

The Company will provide the holders of the Public Shares (the “Public Shareholders”) with the opportunity to redeem all or a portion of their Public Shares upon the completion of the Business Combination, either (i) in connection with a general meeting called to approve the Business Combination or (ii) without a shareholder vote by means of a tender offer. The decision as to whether the Company will seek shareholder approval of a Business Combination or conduct a tender offer will be made by the Company, solely in its discretion. The Public Shareholders will be entitled to redeem their Public Shares, equal to the aggregate amount then on deposit in the Trust Account, calculated as of two business days prior to the consummation of the Business Combination (initially anticipated to be $10.00 per Public Share), including interest (less taxes paid or payable), divided by the number of then issued and outstanding Public Shares, subject to certain limitations as described in the Annual Report. The per-share amount to be distributed to the Public Shareholders who properly redeem their Public Shares will not be reduced by the deferred underwriting commissions the Company will pay to the underwriter (as discussed in Note 6). The Class A ordinary shares will be recorded at redemption value and classified as temporary equity upon the completion of the Initial Public Offering, in accordance with Accounting Standards Codification (“ASC”) Topic 480, “Distinguishing Liabilities from Equity.”

Going Concern Consideration

As of December 31, 2024, the Company had cash of $1,697,777 and working capital of $1,762,262.

Until the consummation of an Initial Business Combination, the Company will be using the funds held outside the Trust Account for identifying and evaluating target businesses, performing due diligence on prospective target businesses, paying for travel expenditures, reviewing corporate documents and material agreements of prospective target businesses, and structuring, negotiating and completing an Initial Business Combination.

In order to finance transaction costs in connection with a Business Combination, the Sponsor or an affiliate of the Sponsor, or certain of the Company’s officers and directors may, but are not obligated to, loan the Company funds as may be required (“Working Capital Loans”). If the Company completes a Business Combination, the Company would repay the Working Capital Loans out of the proceeds of the Trust Account released to the Company. Otherwise, the Working Capital Loans would be repaid only out of funds held outside the Trust Account. In the event that a Business Combination does not close, the Company may use a portion of proceeds held outside the Trust Account to repay the Working Capital Loans, but no proceeds held in the Trust Account would be used to repay the Working Capital Loans. Except for the foregoing, the terms of such Working Capital Loans, if any, have not been determined and no written agreements exist with respect to such loans. The Working Capital Loans would either be repaid upon consummation of a Business Combination, without interest, or, at the lender’s discretion, up to $1,500,000 of such Working Capital Loans may be convertible into private placement shares of the post-Business Combination entity at a price of $10.00 per share. The shares would be identical to the Private Placement Shares. As of December 31, 2024 and 2023, the Company had no outstanding borrowings under the Working Capital Loans.

In connection with the Company’s assessment of going concern considerations in accordance with FASB Accounting Standards Update 2014-15, “Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern,” management has determined that if the Company is unable to complete an Initial Business Combination by February 14, 2026, then the Company will cease all operations except for the purpose of liquidating. The date for mandatory liquidation and subsequent dissolution raises substantial doubt about the Company’s ability to continue as a going concern. Management plans to consummate an Initial Business Combination prior to the mandatory liquidation date. No adjustments have been made to the carrying amounts of assets or liabilities should the Company be required to liquidate after February 14, 2026.