AnaptysBio Announces Positive Rosnilimab Healthy Volunteer Phase 1 Top-Line Data

• Rosnilimab, AnaptysBio’s wholly-owned anti-PD-1 agonist antibody, demonstrated favorable safety and tolerability in single and multiple ascending dose healthy volunteer cohorts
• Robust pharmacokinetic profile, in conjunction with rapid and sustained PD-1 receptor occupancy
• Pharmacodynamic activity resulted in dose-dependent reduction of PD-1+ T cells and antigen-specific immune response, which we believe supports rosnilimab’s potential to treat T-cell driven human inflammatory diseases
• Data support monthly subcutaneous rosnilimab dosing in upcoming AZURE Phase 2 placebo-controlled clinical trial in moderate-to-severe alopecia areata patients

SAN DIEGO, Nov. 15, 2021 (GLOBE NEWSWIRE) -- AnaptysBio, Inc. (Nasdaq: ANAB), a clinical-stage biotechnology company developing first-in-class antibody product candidates focused on emerging immune control mechanisms applicable to inflammation and immuno-oncology indications, today announced positive top-line data from a randomized placebo-controlled healthy volunteer single and multiple ascending dose Phase 1 trial of rosnilimab, its investigational wholly-owned anti-PD-1 agonist therapeutic antibody, previously known as ANB030. Top-line data demonstrated favorable safety, pharmacokinetics and pharmacodynamic results that support advancement of rosnilimab into subsequent patient trials.

“Agonizing the inhibitory function of PD-1 is an exciting new approach to T cell modulation,” said Dr. W. Michael Gallatin, leading anti-inflammatory drug development expert and member of AnaptysBio’s Research and Development Committee. “These data support rosnilimab’s potential to specifically target the subset of T cells expressing PD-1 which are believed to be key drivers of human autoimmune and inflammatory diseases.”

“We are pleased to report promising results for rosnilimab in this healthy volunteer Phase 1 trial,” said Dr. Paul F. Lizzul, chief medical officer of AnaptysBio. “We believe rosnilimab’s mechanism is broadly applicable to T cell driven inflammatory diseases and look forward to initiating our AZURE moderate-to-severe alopecia areata trial.”

A total of 144 subjects were enrolled in the randomized, double-blind, placebo-controlled healthy volunteer Phase 1 trial, where single ascending dose (SAD) cohorts were administered single subcutaneous or intravenous doses of rosnilimab ranging between 0.02mg to 600mg or placebo, while multiple ascending dose (MAD) cohorts received four weekly subcutaneous doses of rosnilimab ranging between 60mg and 400mg or placebo. Dose escalation was conducted subsequent to data safety monitoring board review of safety and tolerability parameters following each single and multiple ascending dose level. 

Rosnilimab was generally well-tolerated and no dose limiting toxicities were observed. The most frequent adverse event reported among SAD cohorts was increased circulating C-reactive protein levels of mild severity in nine (10%) rosnilimab-dosed subjects occurring sporadically in a dose-independent manner and a severe occurrence in one (3.3%) placebo-dosed subject. MAD cohorts reported headache as the most frequent adverse event with mild occurrences in three (12.5%) rosnilimab-dosed subjects and none in placebo subjects. Mild injection site reactions were observed in two subjects (11.1%) administered with multiple subcutaneous rosnilimab doses. Two serious adverse events were reported in single dose cohorts, including obstructive pancreatitis in a placebo-dosed subject and COVID-19 infection in a rosnilimab-dosed subject leading to discontinuation which was deemed unrelated to treatment. No serious adverse events were reported in subjects receiving multiple doses of rosnilimab or placebo. 

Pharmacokinetic analyses demonstrated a favorable profile for rosnilimab with an estimated two-week half-life for subcutaneous and intravenous routes of administration and approximately 80% bioavailability. Low-titer anti-drug antibodies were detected at low single dose levels in 19 (21%) rosnilimab-dosed subjects, but none were detected in high single dose or multiple dose subjects. Full PD-1 receptor occupancy was observed rapidly during the first week following single subcutaneous rosnilimab doses at or above 60mg, and was maintained for at least 30 days at or above 200mg single subcutaneous doses. These data support monthly subcutaneous dosing of rosnilimab for future patient trials.