Danny Rischin, MD, on Adjuvant Cemiplimab for High-Risk CSCC

The C-POST trial is a phase 3 trial in patients with high-risk cutaneous squamous cell carcinoma. They compared adjuvant cemiplimab with placebo. In this trial, patients who had high-risk cutaneous SCC were randomized to either receive cemiplimab for 48 weeks or placebo. These patients had to have had surgery with complete macroscopic resection and have completed radiotherapy. This was a positive trial with clinically meaningful and statistically significant results: a hazard ratio of 0.32 and a P value of less than .001. So, a 68% reduction in the risk of disease recurrence or death, and this included a decrease in risk of locoregional recurrence and distant recurrences. At this ASCO meeting, we presented further analysis to better understand the benefits of cemiplimab as an adjuvant treatment in this population. In the C-POST trial, patients were selected based on high-risk criteria. These high-risk criteria could be nodal, such as having a lymph node that was greater than 2 cm with extranodal extension or more than 3 nodes, or several high-risk nonnodal criteria, such as in-transit metastases, T4 disease, perineural invasion, if there was involvement clinically or radiologically, or recurrent disease with other high-risk features. So what we wanted to see in these further analyses is whether all of these groups conveyed a disease-free benefit with cemiplimab compared with placebo. So we looked at all of these nodal and nonnodal criteria, and in fact, in every single group, there was similar disease-free benefit with cemiplimab versus placebo. The other thing that we looked at was the interval between completion of radiation and randomization. The protocol stipulated that patients had to start treatment or at least be randomized between 2 and 11 weeks after completing their radiotherapy. The median was 5.6 weeks. So we looked at the group that started within 2 to 6 weeks and the group that started in 6 to 11 weeks. And in fact, there was a similar disease-free benefit, irrespective of the interval since radiation. These analyses were conducted with updated follow-up, with a median follow-up of 30 months, and the overall disease-free benefit is still significant at 0.335. These results further reinforce that this benefit from adjuvant cemiplimab was seen in all the high-risk groups and irrespective of the interval from radiation. Further follow-up is ongoing of the C-POST trial, and longer-term follow-up and survival analysis will be presented at a later date.