If you follow immuno-oncology, you know the deal with MSS colorectal cancer. Checkpoint inhibitors crush it in MSI-high patients. But MSS/pMMR makes up roughly 85% of metastatic CRC cases, and those patients get almost nothing from immunotherapy.
That’s what makes this data from PDS Biotech so striking.
The company published interim Phase 2 results from an NCI-led trial of PDS01ADC, a tumor-targeted IL-12 immunocytokine, in unresectable MSS/pMMR metastatic colorectal cancer. The treatment arm posted a 78% objective response rate and greater than 80% two-year overall survival.
The parallel control cohort in the same trial? About 35% ORR. About 35% two-year survival.
Objective response rate — NCI-led Phase 2 in MSS/pMMR mCRC
78%
~35%
Source: Interim Phase 2, NCI-led trial, Stage 1 data
The mechanism is worth understanding. IL-12 is one of the most potent immune-activating cytokines we know of, but systemic delivery has always been a toxicity nightmare. PDS01ADC is designed to localize IL-12 activity directly to the tumor microenvironment, concentrating immune activation where it counts while keeping systemic exposure manageable.
This isn’t PDS Biotech’s only bet. The company has PDS0101, an HPV16-targeted immunotherapy, running a Phase 3 trial in recurrent/metastatic head and neck cancer. PDS01ADC also showed preliminary activity in metastatic castration-resistant prostate cancer, posting a 9.6-month median progression-free survival and 40% PSA decline in earlier data.
But the CRC numbers are the headline. Doubling the response rate in a population where checkpoint inhibitors have repeatedly failed, in a randomized NCI trial with a built-in control, is the kind of result that gets partnership conversations started.
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Still interim data. Still stage one of the trial. We don’t have granular patient numbers or p-values yet. But if these numbers hold, PDS01ADC could reshape how we treat the 85% of metastatic CRC patients who’ve been watching MSI-high patients benefit from immunotherapy for years while getting none of it themselves.
