Oral pomalidomide, a derivative of thalidomide with immunomodulatory, antiangiogenic, and antiproliferative properties, proved to be well tolerated and effective against Kaposi’s sarcoma (KS) in a small phase I/II study, investigators reported in the Journal of Clinical Oncology.
There is a substantial need for oral therapies for KS, which often recurs and requires treatment, at least intermittently, for years. Existing treatments are cytotoxic agents, such as anthracyclines that are poorly tolerated and unsuitable for long-term use, said Mark N. Polizzotto, MD, of the National Cancer Institute, Bethesda, Md., and his associates.
They examined the tolerability and efficacy of pomalidomide against KS in a single-center, open-label trial involving 21 men and 1 transgender woman who had at least five evaluable cutaneous lesions. Fifteen of these participants had HIV infection. All of the patients were heavily pretreated with antiretrovirals and other agents, including thalidomide or lenalidomide, and most (17) had advanced KS with tumor-associated edema. The study participants received 5-mg oral pomalidomide once daily for 21 days in 28-day cycles for up to 12 cycles.
Sixteen patients showed an objective tumor response (overall response rate, 73%), including four who achieved a complete response (ORR, 18%). All 7 of the participants who didn’t have HIV showed an objective tumor response (ORR, 100%), as did 9 of the 15 HIV-infected participants (ORR, 60%). Three more participants, including one who was nonadeherent and lost to follow-up, achieved a partial tumor response.
Tumor responses included a decrease in the number of lesions and a decrease in the number of nodular lesions, as well as complete flattening of lesions, resolution of edema, and improvement in appearance. “The latter is particularly important because visible KS is a major source of stigma,” Dr. Polizzotto and his associates said (J Clin Oncol. 2016 Oct 3;34[34]:4125-32).
Two patients reported substantial subjective improvement in foot pain and appearance; one said he was pleased to be able to resume wearing closed shoes, the investigators noted. Treatment response generally was rapid, often commencing before the first follow-up at 4 weeks.
Pomalidomide was generally well tolerated. Adverse effects were frequent but mild and self-limiting, and they included neutropenia, constipation, anemia, fatigue, and rash. No patients required hospitalization, and there were no thromboembolic events. Three study participants developed malignancies after treatment: an Epstein-Barr-virus–associated Hodgkin lymphoma 1 year after the trial, a primary effusion lymphoma 15 months after, and a squamous-cell skin carcinoma. These probably reflect the patients’ underlying immunodeficiency, but the possibility that pomalidomide could contribute to malignancies in this high-risk population should be carefully explored in future studies, the investigators said.
“In resource-rich regions, pomalidomide may be of particular use in HIV-uninfected patients, in patients who have received substantial cumulative doses of anthracyclines, and in patients with less extensive but symptomatic disease for whom avoidance of cytotoxic chemotherapy would be beneficial. In resource-limited regions, there is an urgent need for effective and tolerable oral agents; with appropriate safeguards and monitoring, pomalidomide could address this,” Dr. Polizzotto and his associates wrote.
“Confirmatory studies of pomalidomide, alone and in combination with cytotoxic chemotherapy, are planned, including in sub-Saharan Africa,” they added.