Zenas BioPharma, Inc.

Loan Agreement

On March 14, 2026, the Company entered into the Loan Agreement with Credit PLC (the “Collateral Agent”), BPCR Limited Partnership and BioPharma Credit Investments V (Master) LP, which are funds managed by Pharmakon and the guarantors party thereto. The Loan Agreement provides for up to a $250.0 million Term Loan that matures on March 27, 2031 and consists of five tranches including (1) a Tranche A Loan of $75.0 million drawn ten business days following the execution of the Loan Agreement, (2) a Tranche B Loan of $50.0 million which will be required to be drawn (and up to an additional $25.0 million that the Company may elect to draw) by no later than November 1, 2027, subject to the occurrence of the Tranche B/C Approval Condition, (3) a Tranche C Loan of $25.0 million (less any amounts elected to be (and actually) drawn under the Tranche B Loan in excess of $50.0 million) which will be available at the Company’s election, subject to the occurrence of the Tranche B/C Approval Condition, no later than April 28, 2028, (4) a Tranche D Loan of $50.0 million which will be available at the Company’s election no later than October 30, 2028, subject to the occurrence of the Tranche B/C Approval Condition and achievement of certain milestones in respect of certain net sales levels and (5) a Tranche E Loan of $50.0 million which will be available at the Company’s election no later than April 30, 2029, subject to the occurrence of the Tranche B/C Approval Condition and achievement of certain milestones in respect of net sales levels.

The Term Loan bears interest at a rate based upon an annual interest rate of 3-month secured overnight financing rate (subject to a 3.25% floor) plus 5.75% payable quarterly in arrears; provided that the Company may elect for 100% of the interest for the first 24 months following the Tranche A Loan funding date may be paid-in-kind without an increase in the interest rate.

The Company is required pay a funding fee equal to (i) 2.00% of the funding amount of the Tranche A Loan on the funding date of such loan, (ii) 2.00% of $50,000,000 of the funding amount of the Tranche B Loan on the funding date for such loan, (iii) 1.00% of any amounts in excess of $50,000,000 of the funding amount for the Tranche B Loan on the funding date for such loan, and (iv) 1.00% of each of the funding amount of the Tranche C Loan, Tranche D Loan, and Tranche E Loan on each respective funding date.

The Company may elect to prepay the Term Loans in whole or, subject to certain conditions, in part prior to the Term Loan Maturity Date with such prepayments being subject to certain prepayment, make-whole and exit fees. The Term Loans are subject to certain mandatory prepayments, including a repayment in full of all term loans in four equal payments commencing on September 30, 2028 to the extent the Tranche B/C Approval Condition is not met on or prior to June 30, 2028.

The Loan Agreement contains customary affirmative and restrictive covenants and representations and warranties. We and our subsidiaries are bound by certain affirmative covenants setting forth actions that are required during the term of the Loan Agreement, including, without limitation, certain information delivery requirements (including that consolidated financial statements delivered for and after the fiscal year ending December 31, 2026 are not subject to any qualification as to “going concern” or “scope of audit”), obligations to maintain certain insurance, and certain notice requirements. The Loan Agreement contains customary financial covenants, including (i) at all times prior to the satisfaction of the Tranche B/C Approval Condition, a minimum liquidity requirement and (ii) subject to the outstanding aggregate principal amount of Term Loans advanced under the Loan Agreement being equal to or greater than $200.0 million, a minimum trailing

twelve months consolidated net revenue covenant. Additionally, we and our subsidiaries are bound by certain restrictive covenants setting forth actions that are not permitted to be taken during the term of the Loan Agreement, including, without limitation, (i) selling or disposing of assets, (ii) amending, modifying or waiving our rights under material agreements, (iii) consummating change in control transactions unless all amounts becoming due under the Loan Agreement are paid in full immediately upon (and concurrent with) the consummation of any such change in control transaction, (iv) incurring additional indebtedness, (v) incurring non-permitted liens or encumbrances on our or our subsidiaries’ assets, (vi) paying dividends or making any distribution or payment on or redeeming, retiring or purchasing any equity interests, (vii) making payments on subordinated indebtedness and (viii) making investments other than permitted acquisitions and permitted investments, in each case, subject to specified exceptions including, in the case of restrictions on incurrence of additional indebtedness, the ability to incur certain convertible indebtedness and enter into certain permitted royalty financing agreements. The Loan Agreement also contains certain events of default, including the following: (i) failure to pay principal, interest and other amounts when due, (ii) the breach of the covenants under the Loan Agreement, (iii) the occurrence of a material adverse change or a withdrawal event in respect of obexelimab or orelabrutinib, (iv) certain attachments of the credit parties assets and restraints on their business, (v) certain insolvency, liquidation, bankruptcy or similar events, (vi) certain cross-default of third-party indebtedness and royalty revenue contracts, (vii) the failure to pay certain judgements, (viii) material misrepresentations, (ix) the loan documents ceasing to create a valid security interest in a material portion of the collateral, (x) the occurrence of certain ERISA events and (xi) the occurrence of a default under any intercreditor agreement, in each case subject to the grace periods, cure period and thresholds as specified in the Loan Agreement. Upon the occurrence of an event of default, the Lenders may, among other things, accelerate our obligations under the Loan Agreement (including all obligations for principal, interest and any applicable make-whole and prepayment premiums); provided that upon an event of default relating to certain insolvency, liquidation, bankruptcy or similar events, all outstanding obligations will be automatically accelerated.

Our obligations under the Loan Agreement are secured by substantially all of our assets, including our intellectual property. Certain of our subsidiaries may, from time to time after the Tranche A Closing Date, be required to guarantee our obligations under the Loan Agreement and, in connection with such guarantee, pledge substantially all of their assets, including intellectual property, to secure such guarantee.

The foregoing summary of the Loan Agreement is not complete and is qualified in its entirety by reference to the complete text of the Loan Agreement, a copy of which the Company intends to file as an exhibit to its Quarterly Report on Form 10-Q for the quarter ending March 31, 2026.

10b5-1 Plans

During our fiscal quarter ended December 31, 2025, no director or “officer” (as defined in Rule 16a-1(f) under the Exchange Act) of the Company entered into, modified orterminated contracts, instructions or written plans for the purchase or sale of our common stock that are intended to satisfy the affirmative defense conditions specified in Rule 10b5-1(c) under the Exchange Act.