Sun Pharmaceutical Industries Ltd. / Checkpoint Therapeutics, Inc.

Advanced Cutaneous Squamous Cell Carcinoma (cSCC)

40K US cases/yr · $800M Libtayo (cemiplimab) global net product sales, 2024 (cSCC largest segment) per Regeneron 10-K · ~45-50% Objective response rate with anti-PD-1 / anti-PD-L1 checkpoint inhibitors in advanced cSCC (pivotal trial benchmark)

Disease Overview

Cutaneous squamous cell carcinoma is the second most common non-melanoma skin cancer, with approximately 1.8M US cases diagnosed annually (Skin Cancer Foundation estimate). The vast majority are curable with surgical excision or radiation, but approximately 1-5% progress to locally advanced or metastatic disease that is not amenable to curative surgery or radiotherapy. This advanced cSCC population, estimated at 40,000-60,000 US patients annually with roughly 7,000-9,000 deaths, has historically had limited systemic treatment options (platinum-based chemotherapy, EGFR inhibitors cetuximab off-label) with modest response rates and poor tolerability. The arrival of anti-PD-1 immune checkpoint inhibitors transformed the advanced cSCC paradigm: Regeneron/Sanofi's cemiplimab (Libtayo, approved 2018) and Merck's pembrolizumab (Keytruda, approved 2020) achieved ~45-50% objective response rates in pivotal trials. Checkpoint Therapeutics' cosibelimab (UNLOXCYT), approved by FDA in December 2024, is the first anti-PD-L1 (rather than anti-PD-1) checkpoint inhibitor approved for advanced cSCC, offering a potentially differentiated mechanism via PD-L1 blockade that additionally engages ADCC via intact IgG1 Fc. Advanced cSCC is disproportionately a disease of immunocompromised patients (solid-organ transplant, CLL) where checkpoint safety data is limited.

Competitive Landscape

The advanced cutaneous squamous cell carcinoma checkpoint-inhibitor market is dominated by two approved anti-PD-1 agents: Regeneron/Sanofi's cemiplimab (Libtayo), the first-in-class approval in 2018 that generated approximately $800M+ in 2024 global sales with cSCC as its largest indication, and Merck's pembrolizumab (Keytruda), approved for recurrent/metastatic cSCC in 2020 and benefiting from massive cross-indication share. Cosibelimab (UNLOXCYT, FDA-approved December 2024) is the first and only anti-PD-L1 agent approved in this setting; its intact IgG1 Fc mediates antibody-dependent cellular cytotoxicity (ADCC) in addition to checkpoint blockade, a potentially differentiated mechanism for immunosuppressed solid-organ transplant patients where standard anti-PD-1 therapy carries graft-rejection risk. Sun Pharma plans to commercialize UNLOXCYT in the US via Checkpoint's pre-existing infrastructure while leveraging Sun's specialty dermatology and oncology channels. Other competitive pressures include EGFR inhibitor cetuximab (Erbitux, off-label) and emerging bispecific and costimulatory agonist approaches in earlier development. EU approval decision gates the CVR portion of the deal consideration.