MILAN – A checkpoint inhibitor given with or without targeted therapy resulted in robust response rates in patients with advanced basal cell carcinoma, according to an investigator in a recent proof-of-concept study.
The side effect profile for the progressive death 1 (PD-1) inhibitor pembrolizumab (Keytruda), plus or minus the hedgehog pathway inhibitor vismodegib (Erivedge), was “not out of range” with what’s been observed in other cancer types, said Anne Lynn S. Chang, MD, a medical dermatologist at Stanford (Calif.) University.
Taken together, these safety and efficacy results suggest pembrolizumab could prove useful for patients with advanced basal cell carcinomas, Dr. Chang said in an oral presentation at the World Congress of Dermatology.
Unexpectedly, dual therapy with pembrolizumab and vismodegib was not clearly superior to pembrolizumab alone, though the two arms are not directly comparable in this nonrandomized, investigator-initiated study, according to Dr. Chang.
“That was a surprise for us, but this is a subjective and a small study,” she told attendees at the conference.
There is currently a multi-institutional clinical trial underway to evaluate another PD-1 inhibitor, cemiplimab, in patients with advanced basal cell carcinoma previously treated with a hedgehog pathway inhibitor, she said.
While a large fraction of basal cell carcinomas are cured by resection, those that are locally advanced or metastatic to lymph nodes or distant organs are challenging to manage. Hedgehog pathway inhibitors, which include vismodegib and sonidegib, are the only Food and Drug Administration–approved drug class in this setting, but more than half of patients do not have a response to treatment, and another 20% or so will initially respond but develop resistance, Dr. Chang said.
Other treatments that have been tried in advanced basal cell carcinomas include taxanes, platinum-based agents, 5-fluorouracil, and everolimus, but their efficacy is unclear, according to Dr. Chang, because of a lack of systematic studies.
Investigators thought PD-1 inhibitors might be promising in basal cell carcinoma for a few reasons, Dr. Chang said. In particular, PD-1 inhibitor treatment response has been linked to mutational burden and PD–ligand 1 expression, and advanced basal cell carcinomas have the largest mutational burden of all human cancers, a large proportion of which express PD-L1.
There are multiple case reports in the literature suggesting that advanced basal cell carcinoma is responsive to PD-1 inhibitors, she added.
In the study, nine patients received 200 mg infusion of pembrolizumab every 3 weeks, and seven received the pembrolizumab infusions plus oral vismodegib 150 mg per day.
The pembrolizumab monotherapy group included patients who had tumor progression on vismodegib, did not tolerate vismodegib, or had contraindications to vismodegib. The pembrolizumab-vismodegib regimen was used in patients who had prior stable or partial responses to hedgehog pathway inhibitors.
The overall response rate was 38%, or 6 of 16 patients, with a 70% probability of 1-year progression-free survival and 94% probability of 1-year overall survival, Dr. Chang reported.
The results did not make the case that pembrolizumab and vismodegib was superior to pembrolizumab alone, though as Dr. Chang noted, the numbers of patients were small. Response rates were 29% (two of seven patients) in the combination arm and 44% (four of nine patients) in the monotherapy arm.
There were 24 immune-related adverse events in the trial; the most serious was hyponatremia, which was reversible, according to Dr. Chang. The overall rates of grade 3-4 adverse events were 22% for pembrolizumab monotherapy and 17% for dual therapy.
A report on the study has also been published in the Journal of the American Academy of Dermatology.
Funding for the study was provided by Merck. Dr. Chang reported serving as a clinical investigator and advisory board member for studies sponsored by Genentech-Roche, Merck, Novartis, and Regeneron.