Cancer Immunotherapy Trials Network 12: Pembrolizumab in HIV-Associated Kaposi Sarcoma.

Purpose: Cancer Immunotherapy Trials Network 12 demonstrated safety of pembrolizumab in treating advanced cancer in people with HIV. Here, we report results of the Kaposi sarcoma (KS) cohort.

Methods: In this multicenter phase I trial, we enrolled participants with HIV-associated KS on antiretroviral therapy with CD4⁺ ≥50 cells/μL and HIV plasma RNA <200 copies/mL. Pembrolizumab 200 mg intravenously was administered once every 3 weeks for up to 35 cycles. The primary end point was safety, and the secondary end point was KS response by modified AIDS Clinical Trials Group Criteria.

Results: Thirty-two cisgender men enrolled with baseline median CD4⁺ T-cell count of 274 cells/µL. All but nine participants had received previous systemic KS therapy. Participants received a median of 11 cycles of pembrolizumab (range, 1-35). Sixty-six percent had grade ≥1 treatment-emergent adverse events, including one death from polyclonal KS herpesvirus-related B-cell lymphoproliferation. Thirty-one percent had ≥one immune-mediated AEs (imAEs) with 25% requiring systemic steroids. In 29 participants with evaluable KS, the overall response rate (ORR) was 62.1% (95% CI, 42.3 to 79.3) and did not differ by CD4⁺ T-cell count. ORR in the eight participants with evaluable disease without previous KS therapy was 87.5% (95% CI, 47.3 to 99.7). Median duration of response (DOR) was not reached, and the Kaplan-Meier estimate of DOR of ≥12 months was 92.3% (95% CI, 56.6 to 98.8). Median progression-free survival was 28.2 months (95% CI, 4.2 to noncalculable).

Conclusion: Pembrolizumab yielded a high rate of durable responses in HIV-associated KS. imAEs were successfully managed with standard guidelines.