WILMINGTON, DE — Groundbreaking results from the Phase 3 POD1UM-303/InterAACT 2 trial have been published in The Lancet, showcasing the efficacy of retifanlimab (Zynyz®) in combination with carboplatin and paclitaxel for treating inoperable locally recurrent or metastatic squamous cell carcinoma of the anal canal (SCAC). The trial underscores the first and largest global evaluation of a PD-1 inhibitor combined with chemotherapy for this rare form of cancer.
The trial achieved significant milestones, meeting its primary endpoint of progression-free survival (PFS). The combination of retifanlimab and chemotherapy delivered a clinically meaningful 37% reduction in the risk of progression or death compared to the standard chemotherapy regimen alone (Hazard Ratio [HR]: 0.63; 95% Confidence Interval [CI]: 0.47, 0.84). Patients receiving retifanlimab with chemotherapy saw a median PFS of 9.3 months versus 7.4 months for those on placebo.
“The publication of the POD1UM-303/InterAACT 2 trial in The Lancet is a testament to the strength of the data generated for retifanlimab in patients with inoperable locally recurrent or metastatic SCAC, a disease which until recently had seen limited innovation for decades,” said Steven Stein, M.D., Chief Medical Officer at Incyte. “SCAC can be a devastating disease, and patients often have a poor prognosis. These data supported the FDA’s approval of Zynyz® in May 2025, providing U.S. patients the first and only first-line treatment for inoperable locally recurrent or metastatic SCAC.”
Key Findings from the Trial
- Overall Survival: Interim data showed a clinically meaningful six-month improvement in overall survival (29.2 months for the retifanlimab combination group versus 23.0 months for the placebo group).
- Overall Response Rate (ORR): Retifanlimab increased ORR to 55.8%, with a median duration of response doubling to 14 months compared to 7.2 months for placebo.
- Safety Profile: While serious and Grade 3 adverse events were more frequent with retifanlimab plus chemotherapy, toxicities were deemed manageable using established protocols, ensuring treatment delivery was not compromised.
Retifanlimab’s FDA approval in May marked a significant breakthrough for SCAC patients, providing the only first-line treatment for inoperable cases. Submissions for regulatory approval are also under review in Europe and Japan.
“The incidence of SCAC is increasing by approximately 3% annually, driven mainly by endemic human papillomavirus (HPV) infection,” noted Sheela Rao, M.D., Consultant Medical Oncologist at The Royal Marsden National Health Service Foundation Trust. “With no approved treatments available for advanced cases until recently, it is crucial to develop effective therapies for this orphan disease.”
Broader Implications
SCAC, accounting for 85% of anal cancer cases, remains a challenging disease with increasing prevalence linked to HPV and an amplified risk among people with HIV. The approval of Zynyz® provides a much-needed option for patients facing advanced disease, establishing a new standard of care.
The POD1UM-303/InterAACT 2 trial results, paired with FDA approval, represent a pivotal turning point in addressing the unmet medical needs of SCAC patients. By extending survival and improving treatment responses, retifanlimab has the potential to alter the disease trajectory for patients worldwide.
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