MILAN – In an updated analysis of a pivotal phase 2 study, Michael R. Migden, MD, said at the World Congress of Dermatology.
Median duration of response was not reached at the time of the analysis, with probability of no progression or death above 80% at the 20-month mark, according to, of the department of dermatology at the University of Texas MD Anderson Cancer Center, Houston.
The safety profile of cemiplimab in this study was comparable with what has been reported for other anti–programmed death agents, he said in an oral presentation at the meeting.
While the median time to response was less than 2 months, about one-fifth of patients with locally advanced disease had “unconventional” late responses, occurring up to 10 months after starting treatment, Dr. Migden said. “If you’re just putting someone on some agent like this for a few months, and say, ‘well, I don’t see anything improving,’ it could be one of these patients in this 20% that deserve a little bit longer therapy.”
(Libtayo) is the only Food and Drug Administration–approved treatment for patients with locally advanced or metastatic cutaneous squamous cell carcinoma (CSCC) who are not suitable for curative surgery or radiation, Dr. Migden said in his presentation. That approval was based in part on previously reported results from the phase 2 study, known as EMPOWER-CSCC-1, which demonstrated that cemiplimab had substantial antitumor activity and durable responses.
In this update on, Dr. Migden described results for 78 patients with locally advanced CSCC and 59 with metastatic CSCC who received weight-based intravenous cemiplimab for up to 96 weeks, with optional retreatment for those who had disease progression during the follow-up period. This was an older population, with a mean age of 72 years, and more than 80% were male. About one-third had prior systemic therapy, and the majority had prior cancer-related radiotherapy and surgery.
The objective response rate was 43.6% in the locally advanced group and 49.2% in the metastatic group; this numerical difference of less than 3 percentage points was not statistically significant, according to Dr. Migden.
More importantly, he said, the disease control rate (responses, stable disease, and noncomplete response/nonprogressive disease) was 79.5% in the locally advanced group and 71.2% in the metastatic group.
Time to response was “quite rapid” at a median of 1.9 months in both groups, though 7 of the 34 responders in the locally advanced group had unconventional late responses, taking 6-10 months to get to the point of response, Dr. Migden said.
The probability of being event free (such as no progression or death) has remained relatively flat, he added. In the metastatic cohort, event-free probability was 96.4% at 6 months, 88.9% at 12 months, and 82.5% at 20 months, with a 16.5-month median duration of follow-up, while in the locally advanced cohort, the event-free probability was 96.2% at 6 months, 87.8% at both 12 months and 20 months, with a median follow-up of 9.3 months.
Serious treatment-emergent adverse events were reported for 28.5% in these patients, though Dr. Migden noted that treatment emergent does not necessarily mean related to the study drug. Immune-related adverse events of grade 3 or greater were seen in 11.7% of patients, and adverse events leading to discontinuation were reported for 8.8%.
Dr. Migden reported disclosures related to Regeneron, Novartis, Genentech, Eli Lilly, and Sun Pharmaceutical.