IO Biotech sees potential despite cancer vaccine study failure.

IO Biotech's cancer vaccine, Cylembio, failed to meet its primary objective in a Phase 3 trial for melanoma treatment. Despite this, the company believes the vaccine's performance warrants consideration for FDA approval. The vaccine showed a 23% lower relative risk of death or disease progression compared to Keytruda alone, although the difference was not statistically significant. Other analyses, including one involving people who had not previously received immunotherapy, showed potentially stronger benefits. IO Biotech's CEO described the failure as a "narrow miss."

IO Biotech's cancer vaccine, Cylembio, has failed to meet its primary objective in a Phase 3 trial for melanoma treatment. Despite this, the company remains hopeful that the vaccine's performance warrants consideration for FDA approval. The trial evaluated Cylembio in combination with Merck's anti-PD-1 therapy, Keytruda, versus Keytruda alone as a first-line treatment for 407 patients with unresectable or metastatic melanoma.

The primary endpoint of progression-free survival (PFS) showed a median of 19.4 months in the Cylembio combination cohort compared to 11 months for the Keytruda group. However, the hazard ratio of 0.77 equated to a P value of 0.056, just missing the threshold for statistical significance [1].

IO Biotech's Chief Medical Officer, Qasim Ahmad, M.D., highlighted encouraging trends in overall survival (OS) data, which is expected to mature in the next six to nine months. The company plans to meet with the FDA this fall to discuss the totality of data and determine next steps for a potential regulatory submission [2].

The trial's mixed signals included significant subgroup benefits. Patients without prior anti-PD-1 therapy saw a hazard ratio of 0.74 (p=0.037), and those with PD-L1-negative tumors achieved a hazard ratio of 0.54 (p=0.006). These results align with the FDA's recent trend of subgroup-based approvals, where therapies demonstrate meaningful benefits in specific patient populations despite mixed primary endpoints [3].

IO Biotech's financial runway extends into Q2 2026, providing a buffer to navigate regulatory delays. The company's T-win® platform and ongoing trials in earlier-stage cancers diversify its risk profile. Investors should monitor the FDA's decision, pending OS data, and pipeline progress to assess Cylembio's potential as a first-line melanoma treatment.

References:
[1] https://www.fiercebiotech.com/biotech/cancer-vaccines-narrow-phase-3-fail-wont-stop-io-heading-fda
[2] https://www.ainvest.com/news/io-biotech-cylembio-trial-navigating-outcomes-fda-pathways-oncology-innovation-2508/
[3] https://finance.yahoo.com/news/io-biotech-announces-clinical-improvement-120000640.html