Zenas BioPharma Inc. SEC Filings

Zenas BioPharma (ZBIO)95% relative reduction in the cumulative number of new Gd‑enhancing T1 lesions over weeks 8 and 12 versus placebo (p=0.0009).

The adjusted mean number of new Gd‑enhancing T1 lesions per scan was 0.01 (95% CI: 0.00, 0.06; n=72) with obexelimab compared to 0.23 (95% CI: 0.11, 0.51; n=38) with placebo. Obexelimab also significantly reduced new and/or enlarging T2 lesions. The safety profile was consistent with prior trials, with infections and hypersensitivity reported, most commonly mild injection‑site reactions.

The company plans to report 24‑week MoonStone data in Q1 2026. Additional milestones include topline Phase 3 INDIGO results in IgG4‑RD around year‑end 2025, SunStone Phase 2 topline in SLE in mid‑2026, a global Phase 3 in PPMS underway for orelabrutinib, and a Phase 3 in SPMS expected to start in Q1 2026.

Zenas BioPharma (ZBIO) filed a Form 3 disclosing initial beneficial ownership by Jisong Cui. The filing reports direct ownership of 5,000,000 shares of common stock as of the event date 10/07/2025. The relationship section indicates Director. The signature line lists Jisong Cui as Chairperson and CEO. Table II shows no derivative securities reported.

Zenas BioPharma (ZBIO) reported an insider transaction by a director. On October 9, 2025, the reporting person purchased 63,158 shares of common stock at $19 per share, acquired from the issuer pursuant to a Securities Purchase Agreement dated October 7, 2025.

Following the transaction, the filing lists 1,173,395 shares indirectly held through SR One Capital Opportunities Fund I, LP and 1,946,564 shares indirectly held through SR One Capital Fund II Aggregator, LP. The reporting person disclaims beneficial ownership except to the extent of any pecuniary interest.

Zenas BioPharma (ZBIO): Form 4 insider purchase — SR One–affiliated entities reported open-market acquisitions of common stock on October 9, 2025 at $19 per share. The filing lists two purchases: 63,158 shares and 63,157 shares, acquired pursuant to a Securities Purchase Agreement dated October 7, 2025.

Following these transactions, beneficial holdings reported include 1,173,395 shares (indirect, Note 2), 1,917,895 shares (indirect, Note 3), and 1,946,564 shares (indirect, Note 4). The reporting person is indicated as a Director and 10% Owner, with the form filed by more than one reporting person.

Zenas BioPharma (ZBIO) reported insider purchases tied to a private financing. A board member bought 11,990 shares of common stock at $20.85 per share under a Securities Purchase Agreement that closed on October 9, 2025. In the same transaction, Longitude Venture Partners IV, L.P. acquired 105,265 shares at $19.00 per share. Following these trades, the filing lists 11,990 shares held directly, plus 1,832,669 shares held indirectly through LVPIV and 774,530 shares held indirectly through Longitude Prime Fund, L.P., reflecting the reporting person’s beneficial ownership structure.

Insider purchase by a director and CEO: The filing shows that on 10/07/2025 the Leon O. Moulder, Jr. Revocable Trust acquired 36,928 shares of Zenas BioPharma common stock at $20.85 per share under a Securities Purchase Agreement. The reporting person, Leon O. Moulder Jr., is listed as the company’s Chief Executive Officer and Chairman and discloses indirect holdings of 1,672,039 shares through Tellus BioVentures LLC and trust holdings noted in the form. The filing includes a disposal of 266,155 shares (nature of that disposition is reported but not further explained here). The report was signed on 10/09/2025.

Amendment discloses additional purchases and updated holdings by Leon O. Moulder, Jr., Tellus BioVentures, LLC and a related trust in Zenas BioPharma common stock. Together the reporting persons now beneficially own 2,594,662 shares, representing 4.8% of the company on a post-transaction basis. The aggregate includes 266,155 shares held directly by Mr. Moulder, 619,540 shares issuable under options exercisable within 60 days, 1,672,039 shares held by Tellus, and 36,928 shares held by the Revocable Trust.

On October 7, 2025 Zenas entered into a PIPE purchase agreement selling an aggregate of 6,311,030 PIPE Shares (split: 6,262,112 to institutional investors at $19.00 per share and 48,918 to directors/officers at $20.85 per share). The Trust purchased 36,928 director/officer PIPE Shares for $769,948.80. The PIPE closed on October 9, 2025, and a registration rights agreement requires a resale registration filing within 15 days of the PIPE closing subject to customary delays.

Zenas BioPharma insiders and affiliated entities reported an insider purchase on 10/07/2025. Fairmount Healthcare Fund II L.P. purchased 316,219 shares of common stock at a price of $19 per share, bringing the fund's indirect beneficial ownership to 2,209,025 shares following the transaction. The Form 4 lists Fairmount Funds Management LLC as investment manager and names Tomas Kiselak and Peter Harwin as managers; Kiselak serves on the issuer's board. Signatures on the filing are dated 10/09/2025.

Director Hongbo Lu reported purchases of Zenas BioPharma (ZBIO) common stock totaling 321,983 shares held indirectly through NextBio entities. The Form 4 shows two non-derivative acquisitions: 58,823 shares bought on 09/13/2024 at $17 per share and 263,160 shares bought on 10/07/2025 at $19 per share, bringing indirect beneficial ownership to 321,983 shares. The filing clarifies these shares are owned directly by NextBio Master Fund LP and NextBio Evergreen LLC and may be deemed indirectly owned by NextBio Capital entities and Mr. Lu in his capacity as a managing member; the reporting person disclaims direct beneficial ownership except for pecuniary interest. The statement is a routine Section 16 disclosure of insider transactions and shows increased insider-aligned position through affiliated investment vehicles.