Abstract CT074: Non-comparative, open-label, multiple cohort, phase 1/2 study to evaluate nivolumab (NIVO) in patients with virus-associated tumors (CheckMate 358): Efficacy and safety in Merkel cell carcinoma (MCC)
Authors: Topalian Suzanne L. , Bhatia Shailender , Hollebecque Antoine , Awada Ahmad , Boer Jan Paul De , Kudchadkar Ragini R. , Goncalves Anthony , Delord Jean-Pierre , Martens Uwe M. , Picazo Jose Maria Lopez , Oaknin Ana , Spanos William C. , Aljumaily Raid , Sharfman William H. , Rao Shangbang , Soumaoro Ibrahima , Cao Alexander , Nghiem Paul , Schadendorf Dirk 
Published: July 2017

Background: NIVO (anti-PD-1) is approved for the treatment of several cancers including advanced melanoma, but its efficacy in other types of skin cancer has not yet been evaluated. MCC is a rare and aggressive form of skin cancer, with most tumors being associated with the Merkel cell polyomavirus. MCCs frequently express PD-L1, and MCC-reactive T cells express PD-1.

Methods: In CheckMate 358 (NCT02488759), patients (pts) with 5 types of advanced virus-associated cancers who had received ≤2 prior therapies, with an ECOG PS of 0-1, were eligible to receive NIVO 240 mg Q2W until progression or unacceptable toxicity. Key exclusion criteria were active brain metastases, autoimmune disease, hepatitis, and HIV infection. Primary endpoints included objective response rate (ORR by RECIST v1.1) and safety; secondary endpoints were duration of response, progression-free survival (PFS), and overall survival (OS). Twenty-five pts with MCC were treated with a median follow-up of 26 wks (range: 5-35).

Results: Among 25 treated pts, median age was 66 yrs, 68% were male, and 60% were treatment-naive; 12 of 18 (67%) tested tumors were virus-positive. In 22 response-evaluable pts, ORR was 68% (table) with ongoing responses in 13 of 15 (87%) pts. Responses occurred in treatment-naive pts (71%), in pts with 1-2 prior systemic therapies (63%), and in both virus-positive and virus-negative tumors; 67% of responses occurred at ~8 weeks. At 3 months, PFS and OS rates were 82% and 92%, respectively. Treatment-related adverse events of any grade and grade 3/4 occurred in 68% and 20% of pts; 12% of pts had treatment-related AEs that led to NIVO discontinuation.

Response to treatmentResponse-evaluable pts (N=22)Treatment-naive pts (n=14)Pts with 1-2 prior systemic therapies (n=8)Best overall response – n (%)Complete response3 (14)3 (21)0Partial response12 (55)7 (50)5 (63)Stable disease4 (18)3 (21)1 (13)Progressive disease3 (14)1 (7)2 (25)ORR – % (95% CI)68 (45–86)71 (42–92)63 (25–92)Time to response, months; median (range)2.0 (1.8–5.3)––Duration of response, months; median (range)Not reached (0.0–5.6)––

Conclusions: NIVO induces rapid and durable tumor regressions in the majority of treatment-naive and treatment-experienced pts with advanced MCC, with a manageable safety profile. Updated clinical response and biomarker data will be presented.

Citation Format: Suzanne L. Topalian, Shailender Bhatia, Antoine Hollebecque, Ahmad Awada, Jan Paul De Boer, Ragini R. Kudchadkar, Anthony Goncalves, Jean-Pierre Delord, Uwe M. Martens, Jose Maria Lopez Picazo, Ana Oaknin, William C. Spanos, Raid Aljumaily, William H. Sharfman, Shangbang Rao, Ibrahima Soumaoro, Alexander Cao, Paul Nghiem, Dirk Schadendorf. Non-comparative, open-label, multiple cohort, phase 1/2 study to evaluate nivolumab (NIVO) in patients with virus-associated tumors (CheckMate 358): Efficacy and safety in Merkel cell carcinoma (MCC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT074. doi:10.1158/1538-7445.AM2017-CT074