1139P - Final results of a phase II study of pembrolizumab as first-line treatment in advanced cutaneous squamous cell carcinomas (CSCCs)

Background

In the CARSKIN study (NCT02883556), first line pembrolizumab demonstrated promising activity and manageable safety in patients (pts) with advanced CSCC. Here we report BOR and survival endpoints.

Methods

Eligible pts with unresectable locally advanced or metastatic CSCC received pembrolizumab. The imaging assessment per RECIST v1.1 was blinded with independent central review. Objectives were BOR, PFS, DOR, OS, and safety in the ITT population; exploratory objectives were BOR and survival endpoints by PD-L1 status in the PP population excluding 2 untreated pts, 1 early non related death and 3 pts tested only with 1 assay. PD-L1 status was centrally assessed by 2 blinded independent pathologists, one using the anti–PD-L1 E1L3N clone (TPS_E1L3N), the other using the 22C3 antibody (TPS_22C3 and CPS_22C3) with a cutoff of 1%.

Results

With a median follow-up of 26 mo, BOR was 47% with 15 PR (26%) and 12 CR (21%); 1y-PFS and OS were 49% and 72% (Table). BOR was significantly higher in PD-L1+ pts than in PD-L1 – pts using TPSE1L3N (p=0.02) or CPS22C3 (p=0.038) but not TPS22C3 (p=0.76). The optimal cutoff of CPS22C3 for BOR using a ROC curve was estimated to be ≥ 7% (Se=0.70, Sp=0.75). Pts with PD-L1+ CSCCs have a significantly better 1y-PFS using TPSE1L3N (p=0.004) but not CPS22C3 and a better 1y-OS with both antibodies (p<0.03). Severe TRAEs occurred in 10 patients (17.5%); 1 pt died of a fatal 2nd aggressive HNSCC. Table: 1139P

Conclusions

Our data confirm promising activity of P in first line treatment of CSCC with a manageable side effect profile. CPS_22C3 ≥ 7% appeared equivalent to TPS_E1L3N ≥ 1% for predicting BOR and OS.

Clinical trial identification

NCT02883556.

Editorial acknowledgement

Legal entity responsible for the study

AP-HP.

Funding

MSD.

Disclosure

E. Maubec: Financial Interests, Institutional, Funding: MSD; Financial Interests, Personal, Speaker, Consultant, Advisor: Sanofi, Pierre Fabre; Financial Interests, Personal, Other: Novartis. P. Petrow, I. Lopez: Other: GE Healthcare, Guerbet. F. Grange: Financial Interests, Institutional, Advisory Board: MSD, BMS. S. Dalac Rat: Financial Interests, Speaker, Consultant, Advisor: BMS, MSD, PFO, Novartis; Non-Financial Interests, Other: BMS, MSD, PFO, Novartis. All other authors have declared no conflicts of interest.