11. Related Party Transactions

Advent BioServices

The following sections describe the contractual arrangements between the Company and Advent prior to the Company’s acquisition of Advent, including operational activities and milestones pursuant to those contracts, and then describe the acquisition in October 2025

The Company had three operational programs with Advent: (a) an ongoing development and manufacturing program at the GMP facility in London, (b) an ongoing development and manufacturing program at the Sawston GMP facility, and (c) periodic specialized programs such as the program related to the MAA pre-requisites, drafting and submission. The Company also executed a SOW #8 covering the work required to establish the DCVax-Direct program in the U.K. and manufacture DCVax-Direct products for global use.

Each of the operational programs was covered by a separate contract. The ongoing manufacturing in the London facility was covered by a Manufacturing Services Agreement (“MSA”) entered into on May 14, 2018. The development and manufacturing program at the Sawston facility was covered by an Ancillary Services Agreement entered into on November 18, 2019. Each periodic specialized

program was covered by an SOW that set forth the role and activities to be undertaken by Advent for that program, and provided for milestone payments upon completion of key elements of the program.

The Ancillary Services Agreement established a structure under which the Company and Advent negotiated and agreed upon the scope and terms for Statements of Work (“SOWs”) for facility development activities and compassionate use program activities, as well as for the periodic specialized programs. After an SOW was agreed and approved by the Company, Advent would proceed with, or continue, the applicable services and would invoice the Company pursuant to the SOW. Since both the facility development and the compassionate use program involved pioneering and uncertainties in most aspects, the invoicing under the Ancillary Services Agreement was on the basis of costs incurred plus fifteen percent. The SOWs could involve ongoing activities or specialized one-time projects and related one-time milestone payments. The Ancillary Services Agreement was to end in July 2023, but the Company has extended the term year by year, to July 2024, to July 2025 and to July 2026.

SOW 8

On November 8, 2024, the Company entered into a Statement of Work #8 (“SOW 8”) with Advent that was incorporated into the Ancillary Services Agreement that was originally entered into dated November 8, 2019 and was extended as described above. SOW 8 covered the work required to establish the DCVax-Direct program in the U.K and manufacture DCVax-Direct products for global use. Under SOW 8, the compensation consisted solely of one-time cash milestone payments for each stage of the work and Advent would only receive the compensation when the applicable work was successfully completed. (When the Company previously contracted with a different company for restart of DCVax-Direct manufacturing, the contract required payment as work was performed, regardless of whether the work was successful or not, as is typical for such contract services. The other company did not succeed in producing any DCVax-Direct products meeting the specifications.)

SOW 8 included the following 5 one-time milestones with corresponding milestone payments (which were only payable after the milestone had been achieved):

(a) Basic Technology Transfer, New SOPs & Regulatory Documents.

Review of documents, specifications and data from the prior DCVax-Direct program conducted by Cognate BioServices. Development of a new set of SOPs for DCVax-Direct production in Sawston and new regulatory documents for the U.K. Initial implementation in Sawston; many engineering runs. Data generation for comparability analyses of both the process and the product. Milestone payment of £0.55 million (approximately $0.7 million) upon completion.

As of October 24, 2025, this milestone had been completed and paid.

(b) Process Development: TFF System vs. Other Systems.

Evaluation of the TFF system used in the prior DCVax-Direct manufacturing. Evaluation of the remaining TFF equipment from the prior program, parts needed to re-establish functional TFF systems, potential sourcing and timelines. Evaluation of remaining disposables from the prior program, requirements for new molds to enable new production of disposables (which are used for each manufacturing run with the TFF system), production arrangements for new disposables, development of new sealing method for disposables, potential sourcing and timelines for disposables. Identification and evaluation of commercially available systems to potentially substitute for TFF system. Engineering runs. Data generation for comparability analyses of TFF system vs. others. Milestone payment of £0.45 million (approximately $0.6 million) upon completion.

As of October 24, 2025, this milestone had been completed but had not yet been paid. The Company had an accrued liability of $0.6 million related to this milestone, which was reclassed to consideration payable to the Seller as of the closing of the acquisition.

(c) Process Development: Existing and New Product Composition.

Worldwide search for sourcing of BCG (1 of 2 essential reagents/ingredients required for DCVax-Direct besides the DCs), due to a severe worldwide shortage. Evaluation of the BCG mechanism of action (MoA) in DCVax-Direct, search for other agents that could have similar MoA or effects, with similar safety profile too. Sourcing of other agents, testing and selection of other agents for a new DCVax-Direct product composition. Many engineering runs. Data generation for comparability analyses of new reagents vs BCG and

new composition of DCVax-Direct vs prior composition. Milestone payment of £0.60 million (approximately $0.8 million) upon completion.

As of October 24, 2025, this milestone had been completed but had not yet been paid. The Company had an accrued liability of $0.8 million related to this milestone, which was reclassed to consideration payable to the Seller as of the closing of the acquisition.

(d) Technology Transfer: Clean Room Implementation.

After the choice of system (TFF vs commercial) and the choice of product composition are decided, development of new SOPs and transfer of production into the clean rooms. This includes pre-clean room engineering runs, establishment of critical quality attributes, and process performance qualifications. For technology transfer into the clean rooms, each employee operator individually must pass 3 consecutive and successful aseptic process simulations in the clean room and also 3 consecutive and successful PQQ runs at scale in the clean room; microbial analysis (sterility, endotoxin, mycoplasma all need to pass); growth promotion tests; validation of all equipment used after being placed in the clean room; validation of all cell analysis assays used via flow cytometry and validation of the fill and finish protocols. Milestone payment of £0.35 million (approximately $0.5 million) upon completion.

As of October 24, 2025, this milestone had been completed but had not yet been paid. The Company had an accrued liability of $0.5 million related to this milestone, which was reclassed to consideration payable to the Seller as of the closing of the acquisition.

(e) New IMPD and New IND.

Draft a new IMPD (Investigational Medicinal Product Dossier) for the revised DCVax-Direct product composition and production process, containing all changes to the manufacturing system, reagents and product composition, processes, sources and/or Mechanism of Action vs. those used in the prior DCVax-Direct program. Also draft a new IND (CMC section), for the first clinical trial with the new manufacturing process and new product composition. Obtain the first approval or clearance of the new IND by a regulator. Milestone payment of £0.35 million (approximately $0.5 million) upon completion.

Advent had completed the new IND CMC section (comprising part of this milestone) but the new IND had not yet been submitted to and approved by regulators (comprising the other part of this milestone).

As of October 24, 2025, the Company had an accrued liability of $0.5 million related to this milestone, which was reclassed to consideration payable the Seller as of the closing of the acquisition.

SOW 6

SOW 6 provides for ongoing baseline costs for manufacturing at the Sawston facility and one-time milestone incentives for (a) regulatory approval of each of the three licenses required for the Sawston facility, (b) successful completion of each of the six workstreams and (c) completion of drafting key portions of an application for product approval (see Note 5 for additional description regarding SOW 6). The milestone incentives are a combination of cash and stock, and are not paid until the milestone is achieved and earned.

During the year ended December 31, 2024, the Company paid an aggregate of $5.0 million in cash, of which $1.0 million was related to two milestones that were completed and fully expensed in 2022, but were unpaid as of December 31, 2022, $4.0 million was payment for four completed one-time milestones (MAA workstream for Mechanism of Action, obtaining a commercial manufacturing license from the MHRA on March 2023 and completion of drafting key portions of the application and submit the application to MHRA for product approval). The Company issued 4.5 million common shares as a result of completion of the two one-time milestones (obtaining a commercial manufacturing license from the MHRA and completion of drafting of the application) at a fair value of $3.2 million, of which $0.6 million was recognized during the year ended December 31, 2024 and $2.6 million had already been recognized (but not paid) in 2022.

The following table summarizes total research and development costs from Advent prior to the Company’s acquisition (in thousands).

The expense for the year ended December 31, 2024 covered 2 one-time milestones: 1) Process development: TFF system vs. other systems, and 2) Process development: existing and new product composition.

Related Party Accounts Payable

As of December 31, 2024, there were outstanding unpaid accounts payable and accrued expenses owed to Advent as summarized in the following table (in thousands). These unpaid amounts are part of the Related Party expenses reported in the above section.

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Acquisition of Advent

The Company entered into an agreement to acquire Advent on August 27, 2025, and closed on the acquisition on October 24, 2025. Prior to the acquisition, Advent was wholly owned by Toucan Holdings LLC (“Seller”). The Company’s Chairperson and Chief Executive Officer, Linda Powers, was the controlling member of the Seller. Following the acquisition, Advent is now a wholly owned subsidiary of the Company.

The consideration for the acquisition will be paid in installments over two years, beginning 3 months after the closing of the acquisition, with potential acceleration after regulatory approval of the Company’s DCVax®-L product. The consideration includes a combination of a cash purchase price of approximately $1.9 million (£1.4 million) and cash payment of an amount equal to the net amount of accounts payable (“Net AP”) that was due from the Company to Advent prior to the acquisition for services already performed under the existing service contracts, totaling $6.0 million, which is net of $2.3 million buyer assumed liabilities, and Excluded Amounts (relating to non-Company matters prior to the acquisition date) were retained by the Seller, totaling approximately $0.7 million (collectively, the “Purchase Consideration”). The unpaid balance will accrue interest at 7.5% annually.

The net assets received by the Company through the acquisition of Advent included 12 million shares of the Company’s common stock and 5.5 million stock options, which the Company had previously issued to Advent as compensation for contract services. The shares of the Company’s common stock were returned to the Company’s treasury and the stock options were cancelled at the Closing Date.