3622 - Pembrolizumab for Recurrent/Metastatic Cutaneous Squamous Cell Carcinoma (cSCC): Efficacy and Safety Results From the Phase 2 KEYNOTE-629 Study

Background

The global, single-arm, phase II KEYNOTE-629 trial (NCT03284424) studied the safety and efficacy of pembrolizumab in patients with recurrent/metastatic (R/M) cSCC.

Methods

Patients with R/M cSCC received pembrolizumab 200 mg Q3W for up to 35 infusions (Grob JJ et al. J Clin Oncol. 2019;37(suppl; abstr TPS9598)). The primary end point was ORR by blinded independent central review per RECIST v1.1. Secondary end points were DOR, DCR, PFS, OS, and safety. DOR, PFS, and OS were estimated using the Kaplan-Meier method. Results of an interim analysis are presented.

Results

Of 105 patients, 76.2% were male, median age was 72 years, 86.7% had previously received ≥1 line of systemic therapy, and 74.3% had previously undergone radiation. At data cutoff (April 8, 2019), median duration of follow-up was 9.5 months (range, 0.4-16.3 months). ORR was 34.3% (95% CI, 25.3%-44.2%); 4 patients (3.8%) achieved CR (95% CI, 1.0%-9.5%), and 32 patients (30.5%) achieved PR (95% CI, 21.9%-40.2%). Median DOR was not reached (range, 2.7-13.1+ months). Of the 36 responders, 31 patients and 7 patients had a minimum follow-up of 6 months and 12 months, respectively, after achieving response; 25 (79.5%) and 1 (65.6%) were estimated to have ongoing responses at > 6 months and >12 months, respectively. DCR (CR + PR + stable disease ≥12 weeks) was 52.4% (95% CI, 42.4%-62.2%). Median PFS was 6.9 months (95% CI, 3.1-8.5 months); 12-month PFS rate was 32.4%. Median OS was not reached (95% CI, 10.7 months-not reached); 12-month OS rate of 60.3%. Treatment-related adverse events (TRAEs) occurred in 70 patients (66.7%), and 6 patients (5.7%) had grade 3-5 TRAEs; 1 patient died of treatment-related cranial nerve neuropathy. The most common TRAEs were pruritus (14.3%), asthenia (13.3%), and fatigue (12.4%).

Conclusions

Pembrolizumab demonstrated a clinically meaningful ORR (34.3%), durable responses, and remarkable PFS and OS in patients with R/M cSCC, most of whom were heavily pretreated. Treatment was well tolerated, and the safety profile was generally consistent with that of other pembrolizumab monotherapy studies; no new safety signals were identified. These data support pembrolizumab for the treatment of R/M cSCC.

Clinical trial identification

NCT03284424, October 26, 2017.

Editorial acknowledgement

Medical writing and/or editorial assistance was provided by Holly Cappelli, PhD, and Dana Francis, PhD, of the ApotheCom pembrolizumab team (Yardley, PA, USA).

Legal entity responsible for the study

Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.

Funding

Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.

Disclosure

J.J. Grob: Honoraria (self): Roche, Novartis, BMS, MSD, Pierre Fabre, Amgen, Sunpharma, Sanofi, Merck, Pfizer; Advisory / Consultancy: Roche, Novartis, BMS, MSD, Pierre Fabre, Amgen, Sunpharma, Sanofi, Merck, Pfizer; Travel / Accommodation / Expenses: Novartis, BMS, MSD, Pierre Fabre. N. Basset-Seguin: Research grant / Funding (institution), Financial contract with St Louis Hospital for the clinical trial: MSD. O. Vornicova: Honoraria (self), Travel / Accommodation / Expenses: BMS; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: MSD; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Novartis; Honoraria (self), Travel / Accommodation / Expenses: Roche. J. Schachter: Honoraria (self): BMS; Honoraria (self): Novartis; Advisory / Consultancy, Travel / Accommodation / Expenses: MSD. N. Meyer: Advisory / Consultancy, Research grant / Funding (institution), Personal fees: MSD; Advisory / Consultancy, Research grant / Funding (institution), Personal fees: BMS; Advisory / Consultancy, Personal fees: Roche; Advisory / Consultancy, Personal fees: Novartis; Advisory / Consultancy: Incyte; Non-remunerated activity/ies, Personal fees: Sun pharma; Advisory / Consultancy, Personal fees: Pierre Fabre. F. Grange: Advisory / Consultancy: MSD. J.M. Piulats: Research grant / Funding (institution), Travel / Accommodation / Expenses: BMS; Research grant / Funding (institution): MSD; Research grant / Funding (institution): Pfizer; Research grant / Funding (institution): Merck Serono; Research grant / Funding (institution): Incyte; Research grant / Funding (institution): AstraZeneca; Travel / Accommodation / Expenses: Roche; Travel / Accommodation / Expenses: Janssen. J. Bauman: Advisory / Consultancy: Pfizer; Advisory / Consultancy: Bayer. P.(. Zhang: Full / Part-time employment: Merck & Co., Inc.. B. Gumuscu: Full / Part-time employment: MSD. R.F. Swaby: Full / Part-time employment: Merck & Co., Inc.. B.G.M. Hughes: Advisory / Consultancy: MSD; Advisory / Consultancy: BMS; Advisory / Consultancy: AstraZeneca; Advisory / Consultancy: Roche; Advisory / Consultancy: Pfizer; Advisory / Consultancy: Boehringer. All other authors have declared no conflicts of interest.