Zenas BioPharma reported Phase III INDIGO trial success for obexelimab in IgG4-related disease (IgG4-RD), but efficacy trailed Amgen’s Uplizna, leading to a sharp stock decline.

Why It Matters To Oncology

• IgG4-RD can cause irreversible organ damage—targeting B cell inhibition with obexelimab may provide a new, less immunosuppressive approach for autoimmune conditions with oncologic implications.

• The INDIGO trial (NCT05662241) showed a 56% flare reduction vs placebo; Uplizna previously reported an 87% reduction in the MITIGATE trial.

The Financials

• Zenas shares plunged 52% as investors compared the efficacy to Uplizna's, despite positive secondary endpoints and safety profile.

• CEO sees IgG4-RD as a “significant commercial opportunity” and obexelimab as a potential franchise for rheumatic diseases.

What They're Saying

• Zenas’ CMO: The drug’s dual CD19/FcγRIIb targeting and weekly subcutaneous dosing may offer sustained B cell inhibition without compromising immune defenses.

• Wedbush analysts note the "less harsh mechanism" and dosing flexibility as possible differentiators from Uplizna.

What's Next

• FDA filing for obexelimab expected Q2, with EU submission to follow in late 2024.

• Further data in multiple sclerosis and lupus due later this year; full INDIGO results to be presented at an upcoming medical meeting.