The increase in length of survival without disease progression was measured in months; 5.6 months for the combination patients vs a study-wide low of ipilimumab-only patients (2.6 months). The ipilimumab-only group was notably the smallest, at only 9 patients, and skewed older, with 66% over the age of 60 years. Patients who had monotherapy with nivolumab experienced a PFS of 2.9 months, while those who received pembrolizumab averaged a PFS of 3.2 months. Notably, there was no significant difference between the cohorts in overall survival.
With PFS being a desirable goal for most patients, the authors described positive prognostic factors for that outcome. Patients who had an Eastern Cooperative Oncology Group (ECOG) performance score of less than 1, patients whose tumors were most responsive to treatment (by RECIST 1.1 criteria), and patients on combination therapy were most likely to enjoy longer time periods without a change in disease status.
“Although ICIs were less efficacious in Taiwanese patients with melanoma, ICIs still provide an alternative option for Taiwanese patients seeking a robust response profile with tolerable toxicity,” the authors concluded.
The small study population was highly variable, with some patients receiving ICI therapy from prior chemotherapy, others receiving cytokine therapy, and others who received prior BRAF inhibitor (BRAFi) or other therapy. Some had acral melanoma, some had cutaneous melanoma, and others had mucosal melanoma.
Patients who rapidly deteriorated were pulled from the study and categorized as “not assessed,” which may be of concern to clinicians wishing to assess the value of combining ICIs, especially in a less-than-optimal patient populations, such as someone with lower functional status or who had responded poorly to prior treatment. The risk of serious and bothersome side effects may not be worthwhile in this case — when the disease is only being arrested for months, rather than years.
The authors noted that their study might have been higher-powered had there not been a relatively low incidence of melanoma in Taiwan. They also noted that the high cost of ICI treatment presented a barrier to patients until very recently; in April 2019, Taiwan added the therapy to the formulary for its national health insurance. Patients in countries without such access would therefore need to weigh potential cost against risks of side effects and the likelihood of efficacy with their physicians. Notably, the patients with longer PFS in this study were on multiple ICIs, which implies greater financial cost.
Dr Chan said she appreciated the unique information from the Taiwanese study, though it wasn’t a perfectly randomized and controlled trial. “In general, retrospective studies may provide more limited information compared to a prospective study, but it is helpful to have data focusing on a specific ethnic population.”
Wu C-E, Yang C-K, Peng M-T, et al. Immune checkpoint inhibitors for advanced melanoma: Experience at a single institution in Taiwan. Front Oncol. 2020;10:905.