License and Collaboration Revenue	12 Months Ended
Dec. 31, 2025
License and Collaboration Revenue
License and Collaboration Revenue	7.License and Collaboration Revenue License and Collaboration Agreement with Bristol-Myers Squibb In August 2023, the Company entered into a license and collaboration agreement (the “BMS Agreement”) with BMS, under which the Company granted BMS an exclusive license to (i) develop, manufacture (subject to the Company’s rights to be the exclusive manufacturer for BMS for a certain period of time), commercialize or otherwise exploit obexelimab and any biological product (irrespective of presentations, formulations or dosages) containing obexelimab but not any of the Company’s other proprietary active ingredient (the “BMS Product”) into Japan, South Korea, Taiwan, Singapore, Hong Kong and Australia (collectively, the “BMS Territory”) and (ii) develop and manufacture obexelimab and the BMS Product outside the BMS Territory provided that obexelimab and the BMS Product are solely used in the BMS Territory. Pursuant to the BMS Agreement, BMS paid the Company a one-time non-refundable upfront cash payment of $50.0 million. The Company is entitled to receive further separate development, regulatory milestone payments from BMS of up to approximately $79.5 million. The Company is also entitled to receive one-time sales milestone payments up to $70.0 million upon BMS achieving certain net sales milestones in a given year in the BMS Territory. The Company is also eligible to receive tiered high single-digit to low double-digit royalties on net sales in the BMS Territory, subject to specified reductions. The Company will continue to perform and oversee the ongoing Phase 3 trial of obexelimab in the IgG4-RD indication and BMS will participate in the performance of the study. BMS also has the right to participate in other global clinical studies that the Company chooses to perform. Pursuant to such global studies, including the IgG4-RD study, the Company and BMS have defined roles with specified activities assigned to each party in their respective jurisdictions. These activities are overseen by a joint steering committee, which has equal representation of the parties. BMS will fund their pro rata share of the total global study costs up to a specified percentage of the patients enrolled in the study from the BMS Territory. BMS is responsible for the development and commercialization of obexelimab within the BMS Territory, including the performance of any local studies within its jurisdiction that it chooses to perform, while the Company retains responsibility for the development and commercialization for the remainder of the world. The Company is responsible for manufacturing the clinical supply and commercial supply of obexelimab, each at cost plus single-digit margin. The Company evaluated the terms of the BMS Agreement to determine whether it is a collaborative arrangement in the scope of ASC 808. The Company concluded that the BMS Agreement is a collaborative arrangement under ASC 808 as both parties are active participants in the global clinical trial and are exposed to significant risks and rewards of those activities. The Company determined that the BMS Agreement contained two material components: (i) the license granted to BMS to develop, manufacture and commercialize obexelimab within the BMS Territory, and related activities in the BMS Territory, including manufacturing and (ii) the global development of obexelimab, which at execution, solely related to the ongoing Phase 3 trial for IgG4-RD. The Company used criteria specified in ASC 606 to determine whether the components of the BMS Agreement are performance obligations to a customer and concluded that BMS is the Company’s customer for the license and related activities in the BMS Territory under ASC 606. The global development activities under the agreement do not represent a transaction with a customer and reimbursement payments received by the Company for global development activities are accounted for as a reduction of the related research and development expenses. The Company recorded $5.5 million and $6.0 million as a reduction to research and development expenses during the years ended December 31, 2025 and 2024, respectively, with $1.2 million and $2.0 million of outstanding receivable, included in prepaid expenses and other current assets on the Company’s consolidated balance sheet as of December 31, 2025 and 2024, respectively. The Company evaluated the license and related activities under ASC 606 as these transactions are considered transactions with a customer, and identified four material promises at the outset of the BMS Agreement, which consists of (i) the exclusive license, (ii) the initial technology transfer, (iii) clinical manufacturing supply related to development in the BMS Territory and (iv) commercial manufacturing supply related to commercialization within the BMS Territory. The Company determined that the exclusive license and initial technology transfer were not distinct from each other, as the exclusive license has limited value without the corresponding technology transfer. As such, for the purposes of ASC 606, the Company determined that the two material promises, the exclusive license and the initial technology transfer, should be combined into one distinct performance obligation. The Company further evaluated the material promise associated with the clinical manufacturing supply and the commercial manufacturing supply, within the BMS Territory, concluding that because BMS is not obligated to purchase any minimum amount, the clinical manufacturing supply and commercial manufacturing supply represent a purchase option and not a performance obligation. The Company further concluded that the customer option is not priced at a significant and incremental discount at the execution of the arrangement and therefore does not represent a material right. Therefore, each of the clinical and commercial manufacturing activities were excluded as performance obligations at the outset of the arrangement. The transaction price of the BMS Agreement was determined to be $50.0 million, which consisted of the upfront cash payment, and was allocated to the one combined performance obligation. The other potential consideration, which includes development, regulatory, and sales milestone payments that the Company is eligible to receive were excluded from the transaction price, as all milestones were not deemed probable of achievement and were therefore fully constrained. The Company issued the BMS Note in connection with the BMS Agreement, and the BMS Note was recorded at fair value separate from the transaction price of the BMS Agreement. In May 2024, the BMS Note was settled through the issuance of convertible preferred stock, which was converted to common stock in September 2024. The Company reevaluates the transaction price at the end of each reporting period as uncertain events are resolved or other changes in circumstances occur, and if necessary, the Company adjusts its estimate of the transaction price, and any addition to the transaction price would be recognized as revenue when it becomes probable that inclusion would not lead to a significant revenue reversal. The Company evaluated the license under ASC 606 and concluded that the license is a functional intellectual property license. The Company determined that BMS benefited from the license along with the initial technology transfer at the time of the transfer, and therefore the related performance obligation is satisfied at a point in time. The Company satisfied the performance obligation through delivery of the license and initial technology transfer and therefore recognized the upfront payment of $50.0 million as revenue during year ended December 31, 2023. The Company did not recognize revenue under this arrangement during the years ended December 31, 2025 or 2024, as no milestones were achieved or deemed probable of achievement, and as such, all remaining milestones remained fully constrained and excluded from the transaction price. Tenacia Biotechnology Co. Novation Agreement In October 2024, the Company entered into a novation agreement with Tenacia, under which the Company transferred its rights and obligations under the agreements with Dianthus to Tenacia (the “Tenacia Agreement”). Pursuant to the Tenacia Agreement, the Company, transferred all the ZB005 inventory, analytical methods and manufacturing records generated, under the Dianthus Option Agreement and the License Agreement (collectively the “Dianthus Agreements”), to Tenacia, for the exclusive right to research, develop, manufacture and commercialize products within China, Hong King, Macau and Taiwan (“greater China”). As a result of the Tenacia Agreement, the Company has no further obligations to Dianthus pursuant to the Dianthus Agreement. Pursuant to the Tenacia Agreement, Tenacia paid the Company a one-time non-refundable upfront cash payment of $5.0 million. The Company is entitled to receive further development, regulatory and sales milestones from Tenacia of up to approximately $86.0 million if certain milestones are successfully achieved. The Company evaluated the terms of the Tenacia Agreement and determined it is within the scope of ASC 606. The Company identified the following promises in the Tenacia Agreement that were evaluated under the scope of ASC 606: (i) transfer of the license, (ii) assignment of all rights, title and interests in ZB005 inventory, manufacturing records, analytical methods and draft IND component, (iii) services to be performed in accordance with manufacturing technology transfer and (iv) transfer, up to one year after the effective date, of any tangible embodiments of know-how that was not previously provided. The Company also evaluated whether certain options outlined in the Tenacia Agreement represented material rights that would give rise to a performance obligation and concluded that none of the options conveyed a material right to Tenacia and, therefore, are not considered separate performance obligations within the Tenacia Agreement. The Company assessed the above promises and determined that the license for ZB005, asset transfer and technology transfer are a combined distinct performance obligation within the scope of ASC 606. The future technology know-how transfer services, for one year after the effective date, is a promise that is separately identifiable. The Company determined the likelihood of Tenacia requesting additional know-how transfer to be remote and any requests to require minimal resource allocation, as the Company has concluded all work on ZB005 within greater China. As such, the Company considered the continued know-how transfer to be immaterial in the context of the promises. Therefore, the license, asset transfer and technology transfer represent a single performance obligation within the scope of ASC 606 at contract inception. The Company concluded that the transaction price of $5.0 million was allocated to the combined performance obligation, which was recognized upon delivery prior to December 31, 2024. The Company used the most likely amount method to estimate variable consideration and estimated that the most likely amount for each potential developmental and regulatory variable consideration milestone payment under the agreement is zero, as achievement of those milestones is uncertain and susceptible to factors outside the Company’s control. Accordingly, all such milestone payments were excluded from the transaction price. Management will reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, will adjust the transaction price as necessary. Sales based milestones structured on the level of sales, were also excluded from the transaction price, as the license is deemed to be the predominant item to which the sales relate. The Company will recognize such revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). As of December 31, 2025, no milestones were achieved or deemed probable of achievement. License Agreement with Zai Lab (Hong Kong) Limited In January 2025, the Company entered into a license agreement (the “Zai License Agreement”), with Zai, under which the Company granted Zai an exclusive sublicense to develop, manufacture and commercialize ZB001 and related programs in greater China. Under the Zai License Agreement, Zai will be responsible for conducting all research and development activities, manufacturing, regulatory and commercialization in greater China. Pursuant to the Zai License Agreement, Zai paid the Company a one-time non-refundable upfront cash payment of $10.0 million. The Company is entitled to receive further development, regulatory and sales milestones from Zai up to approximately $117.0 million if certain milestones are successfully achieved, with passthrough obligations of $21.0 million due to Viridian. The Company is also eligible to receive tiered royalties on net sales in greater China, ranging from the low to mid-single digits, net of passthrough obligations due to Viridian. The Company evaluated the terms of the Zai License Agreement and determined it is within the scope of ASC 606. The Company identified the following promises in the Zai License Agreement that were evaluated under the scope of ASC 606: (i) transfer of the license for ZB001, (ii) licensed technology transfer (iii) licensed material transfer and (iv) continued licensed technology transfer. The Company also evaluated whether certain options outlined in the Zai License Agreement represented material rights that would give rise to a performance obligation and concluded that none of the options conveyed a material right to Zai or were immaterial and, therefore, are not considered separate performance obligations within the Zai License Agreement. The Company assessed the above promises and determined that the license for ZB001 and technology transfer are a combined distinct performance obligation within the scope of ASC 606. The licensed material transfer and the continued technology know-how transfer services are promises that are separately identifiable and considered to be distinct. The Company determined the transfer of the licensed materials and continued technology know-how transfer services were immaterial in the context of the contract based on the minimal resources required to fulfill the obligations and the estimated standalone selling price of the licensed materials. Therefore, the sublicense and technology transfer represent a single performance obligation at contract inception. The Company concluded that the transaction price of $10.0 million was allocated to the combined performance obligation, which was recognized upon delivery prior to March 31, 2025. The Company used the most likely amount method to estimate variable consideration and estimated that the most likely amount for each potential developmental and regulatory variable consideration milestone payment under the agreement is zero, as achievement of those milestones is uncertain and susceptible to factors outside the Company’s control. Accordingly, all such milestone payments were excluded from the transaction price. Management will reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, will adjust the transaction price as necessary. Sales and royalty based milestones structured on the level of sales, were also excluded from the transaction price, as the license is deemed to be the predominant item to which the transaction price relates. The Company will recognize such milestone and royalty revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). As of December 31, 2025, no milestones were achieved or deemed probable of achievement.

License and Collaboration Revenue

12 Months Ended

Dec. 31, 2025

7.License and Collaboration Revenue

License and Collaboration Agreement with Bristol-Myers Squibb

In August 2023, the Company entered into a license and collaboration agreement (the “BMS Agreement”) with BMS, under which the Company granted BMS an exclusive license to (i) develop, manufacture (subject to the Company’s rights to be the exclusive manufacturer for BMS for a certain period of time), commercialize or otherwise exploit obexelimab and any biological product (irrespective of presentations, formulations or dosages) containing obexelimab but not any of the Company’s other proprietary active ingredient (the “BMS Product”) into Japan, South Korea, Taiwan, Singapore, Hong Kong and Australia (collectively, the “BMS Territory”) and (ii) develop and manufacture obexelimab and the BMS Product outside the BMS Territory provided that obexelimab and the BMS Product are solely used in the BMS Territory.

Pursuant to the BMS Agreement, BMS paid the Company a one-time non-refundable upfront cash payment of $50.0 million. The Company is entitled to receive further separate development, regulatory milestone payments from BMS of up to approximately $79.5 million. The Company is also entitled to receive one-time sales milestone payments up to $70.0 million upon BMS achieving certain net sales milestones in a given year in the BMS Territory. The Company is also eligible to receive tiered high single-digit to low double-digit royalties on net sales in the BMS Territory, subject to specified reductions.

The Company will continue to perform and oversee the ongoing Phase 3 trial of obexelimab in the IgG4-RD indication and BMS will participate in the performance of the study. BMS also has the right to participate in other global clinical studies that the Company chooses to perform. Pursuant to such global studies, including the IgG4-RD study, the Company and BMS have defined roles with specified activities assigned to each party in their respective jurisdictions. These activities are overseen by a joint steering committee, which has equal representation of the parties. BMS will fund their pro rata share of the total global study costs up to a specified percentage of the patients enrolled in the study from the BMS Territory.

BMS is responsible for the development and commercialization of obexelimab within the BMS Territory, including the performance of any local studies within its jurisdiction that it chooses to perform, while the Company retains responsibility for the development and commercialization for the remainder of the world. The Company is responsible for manufacturing the clinical supply and commercial supply of obexelimab, each at cost plus single-digit margin.

The Company evaluated the terms of the BMS Agreement to determine whether it is a collaborative arrangement in the scope of ASC 808. The Company concluded that the BMS Agreement is a collaborative arrangement under ASC 808 as both parties are active participants in the global clinical trial and are exposed to significant risks and rewards of those activities. The Company determined that the BMS Agreement contained two material components: (i) the license granted to BMS to develop, manufacture and commercialize obexelimab within the BMS Territory, and related activities in the BMS Territory, including manufacturing and (ii) the global development of obexelimab, which at execution, solely related to the ongoing Phase 3 trial for IgG4-RD. The Company used criteria specified in ASC 606 to determine whether the components of the BMS Agreement are performance obligations to a customer and concluded that BMS is the Company’s

customer for the license and related activities in the BMS Territory under ASC 606. The global development activities under the agreement do not represent a transaction with a customer and reimbursement payments received by the Company for global development activities are accounted for as a reduction of the related research and development expenses. The Company recorded $5.5 million and $6.0 million as a reduction to research and development expenses during the years ended December 31, 2025 and 2024, respectively, with $1.2 million and $2.0 million of outstanding receivable, included in prepaid expenses and other current assets on the Company’s consolidated balance sheet as of December 31, 2025 and 2024, respectively.

The Company evaluated the license and related activities under ASC 606 as these transactions are considered transactions with a customer, and identified four material promises at the outset of the BMS Agreement, which consists of (i) the exclusive license, (ii) the initial technology transfer, (iii) clinical manufacturing supply related to development in the BMS Territory and (iv) commercial manufacturing supply related to commercialization within the BMS Territory. The Company determined that the exclusive license and initial technology transfer were not distinct from each other, as the exclusive license has limited value without the corresponding technology transfer. As such, for the purposes of ASC 606, the Company determined that the two material promises, the exclusive license and the initial technology transfer, should be combined into one distinct performance obligation. The Company further evaluated the material promise associated with the clinical manufacturing supply and the commercial manufacturing supply, within the BMS Territory, concluding that because BMS is not obligated to purchase any minimum amount, the clinical manufacturing supply and commercial manufacturing supply represent a purchase option and not a performance obligation.

The Company further concluded that the customer option is not priced at a significant and incremental discount at the execution of the arrangement and therefore does not represent a material right. Therefore, each of the clinical and commercial manufacturing activities were excluded as performance obligations at the outset of the arrangement.

The transaction price of the BMS Agreement was determined to be $50.0 million, which consisted of the upfront cash payment, and was allocated to the one combined performance obligation. The other potential consideration, which includes development, regulatory, and sales milestone payments that the Company is eligible to receive were excluded from the transaction price, as all milestones were not deemed probable of achievement and were therefore fully constrained. The Company issued the BMS Note in connection with the BMS Agreement, and the BMS Note was recorded at fair value separate from the transaction price of the BMS Agreement. In May 2024, the BMS Note was settled through the issuance of convertible preferred stock, which was converted to common stock in September 2024. The Company reevaluates the transaction price at the end of each reporting period as uncertain events are resolved or other changes in circumstances occur, and if necessary, the Company adjusts its estimate of the transaction price, and any addition to the transaction price would be recognized as revenue when it becomes probable that inclusion would not lead to a significant revenue reversal.

The Company evaluated the license under ASC 606 and concluded that the license is a functional intellectual property license. The Company determined that BMS benefited from the license along with the initial technology transfer at the time of the transfer, and therefore the related performance obligation is satisfied at a point in time. The Company satisfied the performance obligation through delivery of the license and initial technology transfer and therefore recognized the upfront payment of $50.0 million as revenue during year ended December 31, 2023. The Company did not recognize revenue under this arrangement during the years ended December 31, 2025 or 2024, as no milestones were achieved or deemed probable of achievement, and as such, all remaining milestones remained fully constrained and excluded from the transaction price.

Tenacia Biotechnology Co. Novation Agreement

In October 2024, the Company entered into a novation agreement with Tenacia, under which the Company transferred its rights and obligations under the agreements with Dianthus to Tenacia (the “Tenacia Agreement”). Pursuant to the Tenacia Agreement, the Company, transferred all the ZB005 inventory, analytical methods and manufacturing records generated, under the Dianthus Option Agreement and the License Agreement (collectively the “Dianthus Agreements”), to Tenacia, for the exclusive right to research, develop, manufacture and commercialize products within China, Hong King, Macau and Taiwan (“greater China”). As a result of the Tenacia Agreement, the Company has no further obligations to Dianthus pursuant to the Dianthus Agreement.

Pursuant to the Tenacia Agreement, Tenacia paid the Company a one-time non-refundable upfront cash payment of $5.0 million. The Company is entitled to receive further development, regulatory and sales milestones from Tenacia of up to approximately $86.0 million if certain milestones are successfully achieved.

The Company evaluated the terms of the Tenacia Agreement and determined it is within the scope of ASC 606. The Company identified the following promises in the Tenacia Agreement that were evaluated under the scope of ASC 606: (i) transfer of the license, (ii) assignment of all rights, title and interests in ZB005 inventory, manufacturing records, analytical methods and draft IND component, (iii) services to be performed in accordance with manufacturing technology transfer and (iv) transfer, up to one year after the effective date, of any tangible embodiments of know-how that was not previously provided. The Company also evaluated whether certain options outlined in the Tenacia Agreement represented material rights that would give rise to a performance obligation and concluded that none of the options conveyed a material right to Tenacia and, therefore, are not considered separate performance obligations within the Tenacia Agreement.

The Company assessed the above promises and determined that the license for ZB005, asset transfer and technology transfer are a combined distinct performance obligation within the scope of ASC 606. The future technology know-how transfer services, for one year after the effective date, is a promise that is separately identifiable. The Company determined the likelihood of Tenacia requesting additional know-how transfer to be remote and any requests to require minimal resource allocation, as the Company has concluded all work on ZB005 within greater China. As such, the Company considered the continued know-how transfer to be immaterial in the context of the promises. Therefore, the license, asset transfer and technology transfer represent a single performance obligation within the scope of ASC 606 at contract inception.

The Company concluded that the transaction price of $5.0 million was allocated to the combined performance obligation, which was recognized upon delivery prior to December 31, 2024.

The Company used the most likely amount method to estimate variable consideration and estimated that the most likely amount for each potential developmental and regulatory variable consideration milestone payment under the agreement is zero, as achievement of those milestones is uncertain and susceptible to factors outside the Company’s control. Accordingly, all such milestone payments were excluded from the transaction price. Management will reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, will adjust the transaction price as necessary. Sales based milestones structured on the level of sales, were also excluded from the transaction price, as the license is deemed to be the predominant item to which the sales relate. The Company will recognize such revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

As of December 31, 2025, no milestones were achieved or deemed probable of achievement.

License Agreement with Zai Lab (Hong Kong) Limited

In January 2025, the Company entered into a license agreement (the “Zai License Agreement”), with Zai, under which the Company granted Zai an exclusive sublicense to develop, manufacture and commercialize ZB001 and related programs in greater China. Under the Zai License Agreement, Zai will be responsible for conducting all research and development activities, manufacturing, regulatory and commercialization in greater China.

Pursuant to the Zai License Agreement, Zai paid the Company a one-time non-refundable upfront cash payment of $10.0 million. The Company is entitled to receive further development, regulatory and sales milestones from Zai up to approximately $117.0 million if certain milestones are successfully achieved, with passthrough obligations of $21.0 million due to Viridian. The Company is also eligible to receive tiered royalties on net sales in greater China, ranging from the low to mid-single digits, net of passthrough obligations due to Viridian.

The Company evaluated the terms of the Zai License Agreement and determined it is within the scope of ASC 606. The Company identified the following promises in the Zai License Agreement that were evaluated under the scope of ASC 606: (i) transfer of the license for ZB001, (ii) licensed technology transfer (iii) licensed material transfer and (iv) continued licensed technology transfer. The Company also evaluated whether certain options outlined in the Zai License Agreement represented material rights that would give rise to a performance obligation and concluded that none of the options

conveyed a material right to Zai or were immaterial and, therefore, are not considered separate performance obligations within the Zai License Agreement.

The Company assessed the above promises and determined that the license for ZB001 and technology transfer are a combined distinct performance obligation within the scope of ASC 606. The licensed material transfer and the continued technology know-how transfer services are promises that are separately identifiable and considered to be distinct. The Company determined the transfer of the licensed materials and continued technology know-how transfer services were immaterial in the context of the contract based on the minimal resources required to fulfill the obligations and the estimated standalone selling price of the licensed materials. Therefore, the sublicense and technology transfer represent a single performance obligation at contract inception.

The Company concluded that the transaction price of $10.0 million was allocated to the combined performance obligation, which was recognized upon delivery prior to March 31, 2025. The Company used the most likely amount method to estimate variable consideration and estimated that the most likely amount for each potential developmental and regulatory variable consideration milestone payment under the agreement is zero, as achievement of those milestones is uncertain and susceptible to factors outside the Company’s control. Accordingly, all such milestone payments were excluded from the transaction price. Management will reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, will adjust the transaction price as necessary. Sales and royalty based milestones structured on the level of sales, were also excluded from the transaction price, as the license is deemed to be the predominant item to which the transaction price relates. The Company will recognize such milestone and royalty revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

As of December 31, 2025, no milestones were achieved or deemed probable of achievement.