Note 5 – Related party transactions

License Agreement

On June 28, 2022, in connection with the Contribution Agreement, Eureka Therapeutics, Inc. (“Eureka”), Eureka Therapeutics (Cayman) Ltd. (“Eureka Cayman”), and Estrella entered into a License Agreement under which Eureka and Eureka Cayman granted to Estrella a license under certain intellectual property controlled by Eureka for exploitation by Estrella in the Licensed Territory, which primarily includes the United States and the rest of the world, excluding China and the Association of Southeast Asian Nations (ASEAN) countries.

Pursuant to the License Agreement, during the term: (1) Eureka will manufacture and supply, either itself or through an affiliate or a third-party contract manufacturer, all of Estrella’s and its related parties’ clinical quantities requirements of the Licensed Products and final filled and finished (including packaged) drug product form of the Licensed Products (“Drug Product”) for development activities; and (2) Eureka will similarly supply all commercial quantities requirements of Drug Product for such development activities. Furthermore, Eureka and Estrella will form a Joint Steering Committee (“JSC”) to oversee the development and commercialization of the Licensed Products.

The License Agreement requires Estrella to make certain payments, including (a) an “upfront” payment of $1.0 million, payable in 12 equal monthly installments, (b) “milestone” payments upon the occurrence of certain events related to development and sales, with potential aggregate multi-million dollar payments upon FDA approval, and (c) royalty payments of a single-digit percentage on net sales.

As of March 31, 2026 and December 31, 2025, Estrella had no remaining balance of accounts payable - related party related to the upfront payment under the License Agreement. As of March 31, 2026, two development milestones Milestone 1 (IND submission of EB103 to the FDA) and Milestone 2 (first patient dosed in the first clinical trial of a licensed product) had been earned by Eureka under the Agreement. Milestone 1 was paid on October 10, 2023, and Milestone 2 ($50,000) was paid on September 3, 2024, both recorded as research and development expense in the Company’s unaudited condensed consolidated statements of operations.

Services Agreement

On June 28, 2022, Estrella entered into a Services Agreement with Eureka, as subsequently amended by Amendment No. 1 (effective October 1, 2022) and Amendment No. 2 (effective March 1, 2023). Pursuant to the Services Agreement, Eureka performs certain services for Estrella related to technology transfer and technical assistance to facilitate Estrella’s exploitation of the intellectual property licensed from Eureka. Under the Services Agreement, Estrella was to pay Eureka a non-refundable fee of $10.0 million in connection with the Services related to the Investigational New Drug (IND) application for EB103 and reimburses Eureka for reasonable pass-through costs. In addition, Estrella will be charged for other services performed by Eureka outside the scope of the Services per the Service Agreement, at a flat rate, by time or materials or as mutually agreed upon by the parties in writing.

Services provided by Eureka under the Services Agreement commenced in June 2022 and the IND application for EB103 allowance milestone was achieved in March 2023. Following the consummation of the Business Combination on September 29, 2023, the Company remitted approximately $9.3 million to Eureka on October 10, 2023. As of March 31, 2026 and December 31, 2025, the Company has settled all amounts owed under the Services Agreement, and there are no outstanding accounts payable or related-party liabilities associated with this agreement.

Statement of Work

On March 4, 2024, the Company and Eureka entered into Statement of Work No. 001 (“SOW”) relating to the clinical trial services to be performed by Eureka in connection with STARLIGHT-1, the Phase I/II clinical trial of the Company’s product candidate, EB103, a T-cell therapy targeting CD19 using Eureka’s ARTEMIS® T cell technology. The trial is designed to assess the safety, tolerability, recommended Phase II dose, and preliminary anti-cancer activity of EB103 for the treatment of relapsed or refractory (“R/R”) B-cell non-Hodgkin lymphoma (“NHL”) patients.

The SOW is governed by the terms of the Services Agreement (as amended) and incorporates all of its terms by reference. The scope of work includes study start-up, patient dosing and related activities, study close-out, and reporting, as well as regulatory document development, site activation, patient enrollment and consent management, data collection, and pharmacovigilance.

Pursuant to the SOW, Estrella agrees to pay Eureka non-refundable net fees in connection with the achievement of certain milestones set forth in the SOW, with total fees of $33.0 million for achievement of all milestones, excluding additional pass-through costs and expenses incurred by Eureka and payable by Estrella as further described below. Such amount assumes 20 patients to be dosed and one clinical site is activated. An additional $0.5 million would be payable to Eureka if a second site is activated following mutual agreement of Estrella and Eureka. In addition to the milestone payments, Eureka will invoice Estrella quarterly for additional pass-through costs and expenses incurred in connection with its services under the SOW. Pass-through cost details are summarized in the invoice, and supporting documents are provided upon Estrella’s request. Estrella is required to settle invoices within 30 days, with Eureka reserving the right to impose monthly interest charges of 1.5% for undisputed amounts unpaid after 30 days. Estrella will also be responsible for payment of any taxes, fees, duties or charges imposed by any governmental authority in connection with the services provided by Eureka under the SOW, other than any taxes on Eureka’s income.

The first invoice payable to Eureka issued upon execution of the SOW was for $3.5 million, covering the fees associated with the initiation of the study, the preparation and activation of the first study site, and the First Patient First Visit (FPFV) milestones. Prior to the commencement of the patient dosing phase, a deposit of $1.5 million is required to be delivered to Eureka to ensure the readiness for patient treatment expenses and will be applied against the final invoice, and any unused portion will be returned to Estrella following collection of all outstanding fees and costs payable to Eureka under the SOW.

Additional invoices will be issued in connection with patient dosing milestones, amounting to approximately $1.4 million per patient and a total cost of $27.5 million for 20 patients, excluding any pass-through costs and additional expenses. Lastly, a $2.0 million milestone fee will become due in connection with the study close-out phase. Services provided in connection with this milestone include finalizing patient data, trial data cleaning, statistical analysis, and preparing and submitting the final study report.

As of March 31, 2026, the Company has paid $3.5 million to Eureka for fees associated with the study initiation milestones that have been achieved, $5.5 million for patient dosing, $0.5 million for second site activation, and deposited $1.5 million for patient treatment expenses, which will be applied to the final invoice, with any unused portion refunded once all fees are settled. The deposit of $1.5 million was recorded as prepaid expenses, related party, non-current on the unaudited condensed consolidated balance sheets.

As of March 31, 2026 and December 31, 2025, ten and nine patients had been dosed, respectively. The second clinical trial site was activated in April 2025. All costs associated with patient dosing and second site activation were recorded as research and development expenses in the unaudited condensed consolidated statements of operations.

As of March 31, 2026, the Company accrued approximately $8.3 million under accrued liability – related party, related to outstanding dosing milestone payments. As of December 31, 2025, the Company accrued approximately $12.4 million under accrued liability – related party, and recorded $0.5 million as accounts payable – related party, which included amounts related to outstanding dosing milestone payments and second site activation costs.

On May 13, 2024, the Company and Eureka entered into Amendment No. 1 to the SOW, effective as of March 4, 2024, to clarify that in the event that Estrella exercises its right to terminate or suspend the engagement with Eureka by providing written notice to Eureka in accordance with the SOW, Estrella will only be obligated to compensate Eureka for (i) services provided by Eureka pursuant to the SOW (“Services”) in connection with milestones that were achieved prior to the date and time of such written notice, (ii) reasonable and documented pass-through costs incurred by Eureka on behalf of Estrella prior to the date and time of such written notice in connection with providing the Services and (iii) amounts payable to third parties pursuant to commitments reasonably entered into by Eureka on behalf of Estrella prior to the date and time of such written notice in connection with providing the Services, provided that Eureka shall make commercially reasonable efforts to cancel or reduce any such amounts.

Consulting Agreement

On November 1, 2024, the Company entered into a consulting agreement (the “Consulting Agreement”) with CoFame Investment Holding LLC (“CoFame”), a related party, as CoFame’s manager, Hong Zhang, is the Chairperson and a director of the Company. Pursuant to the Consulting Agreement, CoFame provides advisory and consulting services to the Company regarding activities in Asia, including investor relations and potential business collaborations, as mutually agreed from time to time.

As of March 31, 2026, the Company has accrued $18,333 under accrued liability - related party and has no outstanding balance in accounts payable - related party related to CoFame, as all invoices for the period through February 2026 have been settled. As of December 31, 2025, the Company had accrued $18,333 under accrued liability - related party and $36,666 as accounts payable - related party representing unpaid consulting fees due to CoFame. For the three months ended March 31, 2026 and 2025, the Company recorded professional fee expense of approximately $55,000, related to CoFame.

The following table summarizes research and development expenses and general and administrative expenses incurred by the Company in connection with related party transactions for the three months ended March 31, 2026 and 2025, as discussed above.

Series AA Preferred Stock / Eureka Ownership

On June 28, 2022, Estrella and Eureka entered into the Contribution Agreement, pursuant to which Eureka agreed to contribute and assign to Estrella all rights, title and interest in and to the Assets in exchange for 105,000,000 shares of Estrella’s Series AA Preferred Stock. The issued shares of Series AA Preferred Stock were converted to Common Stock immediately prior to the closing of the Business Combination on September 29, 2023. As of March 31, 2026 and December 31, 2025, Eureka collectively owned approximately 59.3% and 66.6% of the Company on a fully diluted basis, respectively. The decrease primarily reflects dilution from the January 2026 Registered Direct Offering and Private Placement (Note 7).

Lease

Refer to “Note 9 – Leases”