Checkpoint inhibitor therapy is effective for patients with HIV-associated Kaposi sarcoma (KS), a recent study has found.
Partial or complete remission was achieved by a majority of patients; others currently have stable disease lasting longer than 6 months, reported Natalie Galanina, MD, of Rebecca and John Moores Cancer Center at the University of California, San Diego, and her colleagues. Earlier this year, investigators reported similar responses to checkpoint inhibitors in two patients with KS that wasn’t associated with HIV.
“An association has been demonstrated between chronic viral infection, malignancy, and up-regulation of programmed death receptor 1 (PD-1) on CD8+ cytotoxic T-lymphocytes,” the authors wrote in Cancer Immunology Research. In particular, “HIV-specific CD8+ T cells have increased PD-1 expression, which … promotes a cellular milieu conducive to oncogenesis.” These factors, together with the results from the previous study, have suggested that checkpoint inhibitors may be effective for patients with HIV-associated KS.
The retrospective study involved 320 patients treated with immunotherapy at Moores Cancer Center from August 2013 through December 2017. From this group, nine cases of HIV-associated KS were found. Median CD4 count was 256 cells/mcL and median viral load was 20 copies/mL. Eight patients were treated with nivolumab and one was treated with pembrolizumab. Median age was 44 years. All patients were male and receiving antiretroviral therapy.
Six patients (67%) achieved remission, with five attaining partial remission and one attaining complete remission (gastrointestinal disease). Of the remaining three patients, two currently have stable disease lasting longer than 6 months, and one has stable disease lasting longer than 3 months.
Muscle aches, pruritus, and low-grade fever were the most common adverse events. No grade 3 or higher drug-related adverse events occurred.
“Most of our patients received one to four prior lines of therapy but still responded to checkpoint blockade,” the authors wrote. “Our observations suggest that patients with HIV-associated KS have high [response rates] to PD-1 checkpoint blockade, without significant toxicity, even in the presence of low [tumor mutational burden] and/or lack of PD-L1 expression.”
Authors reported compensation from Incyte, Genentech, Merck, Pfizer, and others.
SOURCE: Galanina et al. Cancer Immunol Res. doi: 10.1158/2326-6066.CIR-18-0121.