Basis of Presentation and Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2025
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company continues to qualify as a Foreign Private Issuer under SEC rules; however, the Company has voluntarily elected to become a domestic filer, beginning with its Annual Report on Form 10-K for the year ended December 31, 2024, which was filed with the SEC on March 31, 2025 (the “2024 Annual Report”). The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. (“U.S. GAAP”) for interim financial information and the applicable rules and regulations of the SEC for interim reporting. Accordingly, since they are interim statements, they do not include all of the information and disclosures required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair statement have been included. Operating results for the three and six months ended June 30, 2025 are not necessarily indicative of the results that may be expected for other quarters or the year ending December 31, 2025. The condensed consolidated balance sheet as of December 31, 2024 has been derived from the audited financial statements as of that date. These unaudited condensed consolidated financial statements and the notes thereto should be read in conjunction with the audited financial statements included in our 2024 Annual Report.
Principles of Consolidation	Principles of Consolidation The accompanying condensed consolidated financial statements include the accounts of the Company and its direct and indirect subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The following are the Company’s subsidiaries: Directly Held •Connect Biopharma HongKong Limited (“Connect HK”) Indirectly Held •Connect Biopharm LLC •Connect Biopharma Australia PTY LTD •Suzhou Connect Biopharma Co., Ltd. (“Connect SZ”) •Connect Biopharma (Beijing) Co., Ltd •Connect Biopharma (Shanghai) Co., Ltd. •Connect Biopharma (Shenzhen) Co., Ltd
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and disclosures made in the accompanying notes to the financial statements. Our significant accounting policies that involve significant judgment and estimates include revenue recognition, investments, accrued research and development expenses, income taxes and share-based compensation. Actual results could differ materially from those estimates.
Fair Value of Financial Instruments	Fair Value of Financial Instruments A company may elect to use fair value to measure financial instruments. If the use of fair value is elected, any upfront costs and fees related to the item such as debt issuance costs must be recognized in earnings and cannot be deferred. The fair value election is irrevocable and generally made on an instrument-by-instrument basis, even if a company has similar instruments that it elects not to measure based on fair value. Unrealized gains and losses on existing items for which fair value has been elected are reported as a cumulative adjustment to beginning retained earnings and any changes in fair value are recognized in earnings. We have elected to not apply the fair value option to our financial assets and liabilities. Cash and cash equivalents, receivables, prepaid expenses, other assets, accounts payable and accrued expenses, are carried at cost, which is considered to be representative of their respective fair values because of the short-term maturity of these instruments. Available-for-sale investment securities are carried at fair value. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 820, Fair Value Measurements & Disclosures, establishes a fair value hierarchy which prioritizes the inputs used in measuring fair value as follows: •Level 1—Observable inputs such as quoted prices in active markets for identical assets or liabilities. •Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. •Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The Company’s cash equivalents and short-term investment securities are classified within the fair value hierarchy as defined by authoritative guidance. The Company’s investment securities classified as Level 1 are valued using quoted market prices. The Company obtains the fair value of its Level 2 financial instruments from third-party pricing services. The pricing services utilize industry standard valuation models whereby all significant inputs, including benchmark yields, reported trades, broker/dealer quotes, issuer spreads, bids, offers, or other market-related data, are observable. The Company validates the prices provided by the third-party pricing services by reviewing their pricing methods and matrices and obtaining market values from other pricing sources.
Accounts Receivable, Net	Accounts Receivable, Net Accounts receivable are recorded at the invoice amount, net of an allowance for credit losses. The allowance for credit losses reflects accounts receivable balances that are believed to be uncollectible. In estimating the allowance for credit losses, we consider: (1) our historical experience with collections and write-offs; (2) the credit quality of our customers and any recent or anticipated changes thereto; (3) the outstanding balances and past due amounts from our customers; and (4) reasonable and supportable forecast of economic conditions expected to exist throughout the contractual term of the receivable.
Share-Based Compensation Expense	Share-Based Compensation Expense On January 1, 2025, we began using the Black-Scholes option pricing model to estimate the fair value of each option grant on the grant date, in order to better align with our peers. Prior to 2025, we estimated the fair value of each option grant on the grant date using the Binomial option pricing model. This fair value is then amortized using the straight-line single-option method of attributing the value of share-based compensation to expense over the requisite service periods of the awards. Forfeitures are accounted for, as incurred, as a reversal of share-based compensation expense related to awards that will not vest. The fair value of each employee share purchase right is estimated on the grant date using the Black-Scholes option pricing model. The estimated fair value of each purchase right is then expensed on a straight-line basis over the requisite service period, which is generally the purchase period. The Black-Scholes option pricing model requires inputs of subjective assumptions, including each option’s expected life and price volatility of the underlying shares.
Net Income (Loss) per Share	Net Income (Loss) per Share Basic net income (loss) per share is calculated by dividing the net income (loss) by the weighted-average number of ordinary shares outstanding for the period. Diluted net income (loss) per share is computed by dividing the net income (loss) by the weighted-average number of ordinary shares and ordinary share equivalents outstanding for the period determined using the treasury share method. For purposes of this calculation, stock options and employee share purchase rights are considered to be ordinary share equivalents and are included in the calculation of diluted net income (loss) per share only when their effect is dilutive.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Adopted In December 2023, FASB issued Accounting Standards Update (“ASU”) No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”), to enhance income tax reporting disclosures and require disclosure of specific categories in the tabular rate reconciliation. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024. On January 1, 2025, we adopted the provisions of ASU 2023-09 on a prospective basis and the required disclosures will be included in our Annual Report on Form 10-K for the year ending December 31, 2025. The Company does not expect the adoption of ASU 2023-09 to have a material impact on its annual disclosures. ASU 2023-09 did not have an impact on our disclosures included in this Quarterly Report on Form 10-Q. Not Yet Adopted In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40) (“ASU 2024-03”). ASU 2024-03 requires that public business entities disclose additional information about specific expense categories in the notes to financial statements at interim and annual reporting periods. The prescribed categories include purchases of inventory, employee compensation, depreciation, intangible asset amortization, and depletion. ASU 2024-03 may be applied either prospectively or retrospectively and is effective for annual periods beginning after December 15, 2026 and interim periods beginning after December 15, 2027, with early adoption permitted. We are currently evaluating the impact on our disclosures.
Revenue Recognition	Revenue Recognition The Company evaluated the License Agreement which provides Simcere with the right to use the Company’s intellectual property in the Territory. The Company concluded that the License Agreement was subject to Topic 606 because the Company viewed the License Agreement as a contract with a customer as the activities were central to its business operations. As such, the Company assessed the terms of the License Agreement and identified four performance obligations for the license to research, develop, manufacture and commercialize rademikibart in the Territory. The four performance obligations identified include: (i) transfer of the intellectual property and know-how; (ii) transfer of the current manufacturing process; (iii) development and transfer of a new manufacturing process; and (iv) completion of certain rademikibart development services. At inception of each arrangement that includes milestone payments, the Company evaluates where the milestones are considered probable of being reached. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. At the Effective Date, the Company determined the transaction price to be $25 million, which is comprised of (i) a $21 million upfront payment for the grant of license to the Licensee and (ii) $4 million of cost reimbursement upon delivery of certain clinical trial reports. All other milestones are considered to be constrained at the Effective Date because these milestones are not within the control of the Company and therefore these milestones are not included in the transaction price. When an intellectual property license is determined to be a predominant promise in the arrangement, sales-based milestone payments and royalties are recognized at the later of when the associated performance obligation has been satisfied or when the sales occur. For cost reimbursements related to the supply of material for clinical development, the Company recognizes revenue when Simcere obtains control of the goods. For the three and six months ended June 30, 2025, the Company recognized $48,000 in revenue under the License Agreement related to cost reimbursements for clinical materials. For the three and six months ended June 30, 2024, the Company recognized $24.1 million in revenue under the License Agreement, which related to the upfront license fee and achievement of certain development milestones. Allocation of the Transaction Price The transaction price is generally allocated to the identified performance obligations based on the relative stand-alone selling price estimated for each distinct performance obligation. However the Company has allocated certain regulatory and development milestone payments only to certain specific performance obligation(s) where the terms of such payments relate specifically to the Company’s efforts to satisfy the respective performance obligation, and provided that such allocation is consistent with the objective that transaction price is allocated to each performance obligation in order to reflect the consideration to which the Company expects to be entitled to receive in exchange for satisfying those performance obligations. The Company allocated the $25.0 million transaction price based on relative stand-alone selling prices of each performance obligation as $23.8 million for the license, $0.1 million for the transfer of the current manufacturing process, $0.2 million for development and transfer of a new manufacturing process, and $0.9 million for completion of certain rademikibart development services. The Company developed the estimated stand-alone selling price for the license using a discounted cash flows model, which is an income approach. In estimating the stand-alone selling price for each performance obligation, the Company developed assumptions that require judgment and included forecasted revenues, expected development timelines, discount rates, probabilities of technical and regulatory success and costs for manufacturing clinical supplies. The Company utilizes judgment to assess when control of the goods and services transfers to Simcere, to determine whether the performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. When recognizing revenue over time, the Company evaluates the measure of progress each reporting period and, if necessary, adjusts the progress of performance and related revenue recognition. The Company expects to recognize the transaction price, at a point in time or over the expected performance period of each respective performance obligation. The Company began recognizing revenue from the License Agreement once the Company had substantially completed the transfer of the intellectual property and know-how to Simcere. The revenue associated with the transfer of the intellectual property and know-how and transfer of the current manufacturing process were recognized at a point in time upon successful completion of each obligation during the second quarter of 2024. The Company will recognize the revenue associated with the transfer of a new manufacturing process at a point in time upon successful completion of the obligation. For the performance obligation to complete certain development services, the Company recognized the transaction price over the expected performance period using an input method. To measure the progress of this obligation, the Company used the cost-to-cost basis approach to estimate the percentage of completion as this method provides the most faithful depiction of the Company’s performance in transferring control of the services promised to Simcere and represents the Company’s best estimate of the period of the obligation. The performance obligation related to certain rademikibart development services was completed in third quarter of 2024. Milestone Payments The Licensor is entitled to development milestones under the License Agreement and certain regulatory milestone payments which are paid upon receipt of regulatory approvals within the Territory. At the end of each reporting period, the Company will re-evaluate the probability of achievement of each milestone and any related constraint, and if necessary, adjust its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect the reported amount of license and collaboration revenues in the period of adjustment. Royalties As the license is deemed to be the predominant item to which sales-based royalties relate, the Company will recognize revenue when the related sales occur.

Basis of Presentation and Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2025

The Company continues to qualify as a Foreign Private Issuer under SEC rules; however, the Company has voluntarily elected to become a domestic filer, beginning with its Annual Report on Form 10-K for the year ended December 31, 2024, which was filed with the SEC on March 31, 2025 (the “2024 Annual Report”). The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. (“U.S. GAAP”) for interim financial information and the applicable rules and regulations of the SEC for interim reporting. Accordingly, since they are interim statements, they do not include all of the information and disclosures required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair statement have been included. Operating results for the three and six months ended June 30, 2025 are not necessarily indicative of the results that may be expected for other quarters or the year ending December 31, 2025. The condensed consolidated balance sheet as of December 31, 2024 has been derived from the audited financial statements as of that date. These unaudited condensed consolidated financial statements and the notes thereto should be read in conjunction with the audited financial statements included in our 2024 Annual Report.

Principles of Consolidation

The accompanying condensed consolidated financial statements include the accounts of the Company and its direct and indirect subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The following are the Company’s subsidiaries:

Directly Held

•Connect Biopharma HongKong Limited (“Connect HK”)

Indirectly Held

•Connect Biopharm LLC

•Connect Biopharma Australia PTY LTD

•Suzhou Connect Biopharma Co., Ltd. (“Connect SZ”)

•Connect Biopharma (Beijing) Co., Ltd

•Connect Biopharma (Shanghai) Co., Ltd.

•Connect Biopharma (Shenzhen) Co., Ltd

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and disclosures made in the accompanying notes to the financial statements. Our significant accounting policies that involve significant judgment and estimates include revenue recognition, investments, accrued research and development expenses, income taxes and share-based compensation. Actual results could differ materially from those estimates.

Fair Value of Financial Instruments

A company may elect to use fair value to measure financial instruments. If the use of fair value is elected, any upfront costs and fees related to the item such as debt issuance costs must be recognized in earnings and cannot be deferred. The fair value election is irrevocable and generally made on an instrument-by-instrument basis, even if a company has similar instruments that it elects not to measure based on fair value. Unrealized gains and losses on existing items for which fair value has been elected are reported as a cumulative adjustment to beginning retained earnings and any changes in fair value are recognized in earnings. We have elected to not apply the fair value option to our financial assets and liabilities.

Cash and cash equivalents, receivables, prepaid expenses, other assets, accounts payable and accrued expenses, are carried at cost, which is considered to be representative of their respective fair values because of the short-term maturity of these instruments. Available-for-sale investment securities are carried at fair value.

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 820, Fair Value Measurements & Disclosures, establishes a fair value hierarchy which prioritizes the inputs used in measuring fair value as follows:

•Level 1—Observable inputs such as quoted prices in active markets for identical assets or liabilities.

•Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

•Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

The Company’s cash equivalents and short-term investment securities are classified within the fair value hierarchy as defined by authoritative guidance. The Company’s investment securities classified as Level 1 are valued using quoted market prices. The Company obtains the fair value of its Level 2 financial instruments from third-party pricing services. The pricing services utilize industry standard valuation models whereby all significant inputs, including benchmark yields, reported trades, broker/dealer quotes, issuer spreads, bids, offers, or other market-related data, are observable. The Company validates the prices provided by the third-party pricing services by reviewing their pricing methods and matrices and obtaining market values from other pricing sources.

Accounts Receivable, Net

Accounts receivable are recorded at the invoice amount, net of an allowance for credit losses. The allowance for credit losses reflects accounts receivable balances that are believed to be uncollectible. In estimating the allowance for credit losses, we consider: (1) our historical experience with collections and write-offs; (2) the credit quality of our customers and any recent or anticipated changes thereto; (3) the outstanding balances and past due amounts from our customers; and (4) reasonable and supportable forecast of economic conditions expected to exist throughout the contractual term of the receivable.

Share-Based Compensation Expense

On January 1, 2025, we began using the Black-Scholes option pricing model to estimate the fair value of each option grant on the grant date, in order to better align with our peers. Prior to 2025, we estimated the fair value of each option grant on the grant date using the Binomial option pricing model. This fair value is then amortized using the straight-line single-option method of attributing the value of share-based compensation to expense over the requisite service periods of the awards. Forfeitures are accounted for, as incurred, as a reversal of share-based compensation expense related to awards that will not vest. The fair value of each employee share purchase right is estimated on the grant date using the Black-Scholes option pricing model. The estimated fair value of each purchase right is then expensed on a straight-line basis over the requisite service period, which is generally the purchase period. The Black-Scholes option pricing model requires inputs of subjective assumptions, including each option’s expected life and price volatility of the underlying shares.

Net Income (Loss) per Share

Basic net income (loss) per share is calculated by dividing the net income (loss) by the weighted-average number of ordinary shares outstanding for the period. Diluted net income (loss) per share is computed by dividing the net income (loss) by the weighted-average number of ordinary shares and ordinary share equivalents outstanding for the period determined using the treasury share method. For purposes of this calculation, stock options and employee share purchase rights are considered to be ordinary share equivalents and are included in the calculation of diluted net income (loss) per share only when their effect is dilutive.

Recent Accounting Pronouncements

Adopted

In December 2023, FASB issued Accounting Standards Update (“ASU”) No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”), to enhance income tax reporting disclosures and require disclosure of specific categories in the tabular rate reconciliation. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024. On January 1, 2025, we adopted the provisions of ASU 2023-09 on a prospective basis and the required disclosures will be included in our Annual Report on Form 10-K for the year ending December 31, 2025. The

Company does not expect the adoption of ASU 2023-09 to have a material impact on its annual disclosures. ASU 2023-09 did not have an impact on our disclosures included in this Quarterly Report on Form 10-Q.

Not Yet Adopted

In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40) (“ASU 2024-03”). ASU 2024-03 requires that public business entities disclose additional information about specific expense categories in the notes to financial statements at interim and annual reporting periods. The prescribed categories include purchases of inventory, employee compensation, depreciation, intangible asset amortization, and depletion. ASU 2024-03 may be applied either prospectively or retrospectively and is effective for annual periods beginning after December 15, 2026 and interim periods beginning after December 15, 2027, with early adoption permitted. We are currently evaluating the impact on our disclosures.

Revenue Recognition

The Company evaluated the License Agreement which provides Simcere with the right to use the Company’s intellectual property in the Territory. The Company concluded that the License Agreement was subject to Topic 606 because the Company viewed the License Agreement as a contract with a customer as the activities were central to its business operations. As such, the Company assessed the terms of the License Agreement and identified four performance obligations for the license to research, develop, manufacture and commercialize rademikibart in the Territory. The four performance obligations identified include: (i) transfer of the intellectual property and know-how; (ii) transfer of the current manufacturing process; (iii) development and transfer of a new manufacturing process; and (iv) completion of certain rademikibart development services.

At inception of each arrangement that includes milestone payments, the Company evaluates where the milestones are considered probable of being reached. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. At the Effective Date, the Company determined the transaction price to be $25 million, which is comprised of (i) a $21 million upfront payment for the grant of license to the Licensee and (ii) $4 million of cost reimbursement upon delivery of certain clinical trial reports. All other milestones are considered to be constrained at the Effective Date because these milestones are not within the control of the Company and therefore these milestones are not included in the transaction price.

When an intellectual property license is determined to be a predominant promise in the arrangement, sales-based milestone payments and royalties are recognized at the later of when the associated performance obligation has been satisfied or when the sales occur. For cost reimbursements related to the supply of material for clinical development, the Company recognizes revenue when Simcere obtains control of the goods. For the three and six months ended June 30, 2025, the Company recognized $48,000 in revenue under the License Agreement related to cost reimbursements for clinical materials. For the three and six months ended June 30, 2024, the Company recognized $24.1 million in revenue under the License Agreement, which related to the upfront license fee and achievement of certain development milestones.

Allocation of the Transaction Price

The transaction price is generally allocated to the identified performance obligations based on the relative stand-alone selling price estimated for each distinct performance obligation. However the Company has allocated certain regulatory and development milestone payments only to certain specific performance obligation(s) where the terms of such payments relate specifically to the Company’s efforts to satisfy the respective performance obligation, and provided that such allocation is consistent with the objective that transaction price is allocated to each performance obligation in order to reflect the consideration to which the Company expects to be entitled to receive in exchange for satisfying those performance obligations. The Company allocated the $25.0 million transaction price based on relative stand-alone selling prices of each performance obligation as $23.8 million for the license, $0.1 million for the transfer of the current manufacturing process, $0.2 million for development and transfer of a new manufacturing process, and $0.9 million for completion of certain rademikibart development services. The Company developed the estimated stand-alone selling price for the license using a discounted cash flows model, which is an income approach. In estimating the stand-alone selling price for each performance obligation, the Company developed assumptions that require judgment and included forecasted revenues, expected development timelines, discount rates, probabilities of technical and regulatory success and costs for manufacturing clinical supplies.

The Company utilizes judgment to assess when control of the goods and services transfers to Simcere, to determine whether the performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. When recognizing revenue over time, the Company evaluates the measure of progress each reporting period and, if necessary, adjusts the progress of performance and related revenue recognition.

The Company expects to recognize the transaction price, at a point in time or over the expected performance period of each respective performance obligation. The Company began recognizing revenue from the License Agreement once the Company had substantially completed the transfer of the intellectual property and know-how to Simcere. The revenue associated with the transfer of the intellectual property and know-how and transfer of the current manufacturing process were recognized at a point in time upon successful completion of each obligation during the second quarter of 2024. The Company will recognize the revenue associated with the transfer of a new manufacturing process at a point in time upon

successful completion of the obligation. For the performance obligation to complete certain development services, the Company recognized the transaction price over the expected performance period using an input method. To measure the progress of this obligation, the Company used the cost-to-cost basis approach to estimate the percentage of completion as this method provides the most faithful depiction of the Company’s performance in transferring control of the services promised to Simcere and represents the Company’s best estimate of the period of the obligation. The performance obligation related to certain rademikibart development services was completed in third quarter of 2024.

Milestone Payments

The Licensor is entitled to development milestones under the License Agreement and certain regulatory milestone payments which are paid upon receipt of regulatory approvals within the Territory.

At the end of each reporting period, the Company will re-evaluate the probability of achievement of each milestone and any related constraint, and if necessary, adjust its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect the reported amount of license and collaboration revenues in the period of adjustment.

Royalties

As the license is deemed to be the predominant item to which sales-based royalties relate, the Company will recognize revenue when the related sales occur.