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POD1UM-303 showed that adding the immunotherapy retifanlimab to the standard carboplatin-paclitaxel chemotherapy for advanced anal cancer delayed progression by about two months in median terms and reduced the risk of progression by 37 percent, making it the first immunotherapy to improve first-line treatment of this cancer.
POD1UM-303/InterAACT-2 was a global double-blind phase 3 trial by Incyte that randomised 308 patients with untreated inoperable locally recurrent or metastatic anal squamous cell carcinoma to carboplatin and paclitaxel with retifanlimab 500 mg every four weeks or placebo. The primary endpoint was progression-free survival by blinded independent review.
Median progression-free survival was 9.3 months with retifanlimab against 7.4 months with placebo (hazard ratio 0.63), and interim overall survival also favoured the antibody; grade 3 or worse adverse events were 83.1 against 75.0 percent, with neutropenia and anaemia most common. Retifanlimab with carboplatin-paclitaxel was approved in the United States in May 2025 for this indication, and the corpus's metastatic anal cancer page lists it as the first-line standard with carboplatin-paclitaxel alone (InterAACT) where the antibody is unavailable.
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
308 enrolled.
95% CI 7.5 to 11.3 · 95% CI 7.1 to 7.7
Source| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Progression-free survival (blinded independent central review)primary | Retifanlimab + carboplatin + paclitaxel | 154 | 9.3 months | 0.63 (0.47 to 0.84) | 0.0006 (one-sided) | link |
| Placebo + carboplatin + paclitaxel | 154 | 7.4 months | ||||
| Grade 3 or worse adverse events | Retifanlimab + carboplatin + paclitaxel | 154 | 83.1% | - | - | link |
| Placebo + carboplatin + paclitaxel | 154 | 75% | ||||
| Serious adverse events | Retifanlimab + carboplatin + paclitaxel | 154 | 47.4% | - | - | link |
| Placebo + carboplatin + paclitaxel | 154 | 38.8% |
Shares Metastatic and recurrent anal squamous cell carcinoma, Anal cancer (squamous cell carcinoma), Paclitaxel / nab-paclitaxel, Carboplatin and the tag soc-trials.
Shares Metastatic and recurrent anal squamous cell carcinoma, Anal cancer (squamous cell carcinoma), Immune checkpoint inhibitors and the tag soc-trials.
Shares Incyte, Cytotoxic chemotherapy and the tag soc-trials.
Shares Retifanlimab, Incyte and the tag soc-trials.
Shares Carboplatin, Cytotoxic chemotherapy and the tag soc-trials.
Shares Paclitaxel / nab-paclitaxel, Cytotoxic chemotherapy and the tag soc-trials.
Shares Paclitaxel / nab-paclitaxel, Cytotoxic chemotherapy and the tag soc-trials.
Shares Paclitaxel / nab-paclitaxel, Cytotoxic chemotherapy and the tag soc-trials.