ASCO 2025 | A Phase II trial of cisplatin-sensitized radiation therapy with pembrolizumab for vulvar cancer

Vulvar cancer is a very rare malignancy that’s often treated very similarly to how we treat advanced cervical cancer. What we set out to do was to test the hypothesis that adding pembrolizumab, an immune checkpoint inhibitor, to standard of care radiation and chemotherapy would improve outcomes in this disease. A very similar thing has already been shown in cervical cancer, but there have not been any dedicated trials for vulvar cancer, partly because of the rarity of this disease. So what we did was we had patients who had advanced, recurrent, or even metastatic disease who were eligible to receive definitive chemo and radiation, and the chemotherapy is cisplatin, but then added pembrolizumab to this regimen and continued the pembrolizumab for a total of 12 cycles. Our primary outcome was overall response rates, we wanted to see the tumor shrink and people have symptomatic benefit, and we also looked at six-month recurrence-free survival, that was our secondary outcome, then several other immunologic or translational exploratory outcomes. So what we found was that when we combined this treatment together, along with the maintenance, 12 total cycles, we saw a response rate of 75%, which outstripped our statistically predetermined estimate. And we also found that about 70% of patients were disease-free at six months, and many of them extending beyond that. In looking at our translational objectives, we were able to see certain types of T cells we’re looking at expand, which affirmed that we were certainly on the right track.

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