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Abemaciclib was safe and active for the treatment of patients with HIV-associated and -negative Kaposi sarcoma.
Abemaciclib (Verzenio) was well tolerated and led to high response rates for the treatment of patients with HIV-associated and -negative Kaposi sarcoma, according to findings from a phase 1/2 trial (NCT04941274) presented during the 2025 ASCO Annual Meeting.1
Findings from the study demonstrated that efficacy-evaluable patients who received the CDK4/6 inhibitor (n = 31) achieved a Kaposi sarcoma overall response rate (ORR) of 84%. Patients who received prior (n = 21) or no prior (n = 10) therapy for Kaposi sarcoma experienced ORRs of 81% and 90%, respectively. The median treatment duration was 10 cycles and the median time to response was 2.5 months.
“Among all [efficacy-evaluable] participants, we saw an 84% response rate; most of these were partial responses,” Ramya Ramaswami, MBBS, MPH, the Lasker Clinical Research Scholar and a physician-scientist at the National Cancer Institute, National Institutes of Health, in Bethesda, Maryland, said during the presentation. “Among those with no prior Kaposi sarcoma therapy, we saw a remarkable 90% response rate.”
The phase 1/2 study enrolled adult patients with Kaposi sarcoma who had not received strong CYP3A4 inhibitors. Patients with HIV were required to have undergone at least 8 weeks of antiretroviral therapy. All patients were required to have measurable disease, which was defined as a minimum of 5 lesions on the skin, and an ECOG performance status of 2 or less.1,2
The phase 1 portion of the study followed a 3+3 dose de-escalation design. Patients received oral abemaciclib twice daily at 200 mg, 150 mg, or 50 mg.1 During the phase 2 portion, patients received the agent at 200 mg twice daily.2
The dual primary end points were safety and tolerability as well as ORR.2 Secondary end points included Kaposi sarcoma response, duration of response, and progression-free survival.
At baseline, the median age was 44 years (range, 21-80) in the overall population (n = 34).1 Most patients were male (97%) and had stage T1 disease (82%). Forty-one percent of patients were Black and 18% had stage T0 disease. Moreover, 10 of the patients with stage T1 disease had visceral involvement.
Twenty-five patients had HIV at baseline. Among these patients, the median duration of antiretroviral therapy was 2 years. The median CD4-positive T-cell count at baseline was 427 cells/μL and the median HIV viral load was less than 20 copies/mL.
In terms of safety, the adverse effect profile of abemaciclib was consistent with other studies of the agent. Any-grade neutropenia, diarrhea, and creatinine level increase occurred at respective rates of 88%, 92%, and 76%. Grade 3 and 4 neutropenia were reported at rates of 35% and 15%, respectively. Grade 1 (85%) and 2 (12%) instances of diarrhea occurred. Creatinine level increase was reported at grade 1 or 2 severity at rates of 76% and 32%, respectively.
“The preliminary mechanism of action of abemaciclib may be its effect on cyclin D and KSHV-induced viral cyclin expression,” Ramaswami said. “One limitation to be reminded of is that we conducted this study as a single-center study. We look forward to validating these results in a cohort of patients with advanced T1 stage [disease] that is currently open at our center.”
Disclosures: Ramaswami received research funding from Celgene, CTI BioPharma Corp, EMD Serono, Genentech, and Merck Serono.
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