Seebach, Frank

e18026 Background: Immune checkpoint inhibitor (ICI) therapy is part of standard of care first-line therapy for recurrent or metastatic (R/M) HNSCC. However, less than 20% of patients (CPS ≥1) have an objective response to ICI monotherapy, and most tumors progress within ~3 months. We sought to improve the proportion of patients who benefit from a chemotherapy-free regimen by combining intratumoral (IT) VV1 oncolytic virus (VSV-IFNβ-NIS) injections with the anti-PD-1 antibody, cemiplimab. We report a pre-planned analysis of Simon's stage 1 results. Methods: We activated a phase 2 study testing the efficacy of first line IT VV1 plus cemiplimab in 1 st line patients with R/M HNSCC. A Simon's two-stage design was employed whereby 10 patients would be accrued in stage 1, and if 3 or more responses were observed, 12 additional patients would be accrued for stage 2. The primary endpoint was objective response rate (ORR) per investigator (RECIST 1.1). Eligible patients had untreated R/M HNSCC from primary oropharynx, oral cavity, hypopharynx, or larynx sites with CPS ≥1. Patients had to have at least one measurable lesion amenable to IT injection. Treatment comprised of IT injections to 1-5 lesions of oncolytic VV-1 virus and IV cemiplimab 350 mg on day 1, repeated every 21 days. Each lesion could be injected 3 times; a 4th injection was allowed if a partial response (PR) was achieved after 3 injections. Cemiplimab could be continued for up to 2 years until progression or unacceptable toxicity. Results: Patient and tumor characteristics, as well as efficacy and toxicity are summarized in the table below. Ten patients were treated at the time of Stage 1 analysis, with 3 showing a confirmed PR for ORR of 30%. Responder CPS scores were 45, 12 and 20%. Two of the responders subsequently showed progression after 6.2 and 9.9 months, the third has maintained PR at 7.7 months to date. Eight of 10 patients showed decrease in the sum of target lesion size (mean decrease of 16%; range -57 to 77%). One grade 2 event of ICI nephritis resolved with corticosteroid treatment. Conclusions: Three patients showed confirmed PR by RECIST 1.1 in Simon's stage 1, meeting criteria to proceed to Simon's stage 2. A total of 22 patients in the HNSCC will be enrolled. VV1 plus cemiplimab shows promise in first line R/M HNSCC based on these initial results. Clinical trial information: NCT04291105 . Patient demographics. N (treated) 10 Sex 20% female Median age (y) 60 (54 – 76) Oropharynx 7 HPV+ 7 Oral cavity 3 PD-L1 CPS median (range) 7.5 (1-45%) Locoregional injection 3 Distant injection 6 Local and distant injection 1 Best response (RECIST 1.1) PR 3 SD 5 PD 2 Adverse Events #pts any VV1/cemiplimab-related G3 AE 4 Lymphopenia 3 Elevated ALK 1

Abstract Background: Cemiplimab is the first treatment approved in the US (as cemiplimab-rwlc) for patients with metastatic basal cell carcinoma (mBCC) or locally advanced disease (laBCC) after hedgehog inhibitor (HHI) treatment or for whom an HHI is not appropriate. Cemiplimab provided substantial clinical benefit and an acceptable safety profile in patients with laBCC who discontinued HHI therapy due to progressive disease (PD), intolerance, or no better than stable disease (SD) after 9 months (NCT03132636). Here, we present the primary analysis of the mBCC cohort. Methods: Patients with mBCC (nodal or distant) post-HHI treatment received cemiplimab 350 mg intravenously every 3 weeks for up to 93 weeks or until PD. The primary endpoint was objective response rate (ORR) by independent central review (ICR). Key secondary endpoints included safety and tolerability, ORR per investigator (INV) assessment, duration of response (DOR), progression-free survival (PFS), overall survival (OS), and complete response (CR) rate (data cutoff date: May 20, 2021). Results: Fifty-four patients were enrolled (70.4% male; median age 63.5 years [range, 38−90]; Eastern Cooperative Oncology Group performance status 0 [66.7%] and 1 [33.3%]). Median duration of follow-up was 8.4 months (range 1.5-36.2). ORR per ICR was 24.1% (95% confidence interval [CI], 13.5-37.6); with 1 CR and 12 partial responses (PRs). ORR per INV was 25.9% (95% CI, 15.0-39.7), with 2 CRs and 12 PRs. Among responders, median time to response per ICR was 4.0 months (range, 2.0−10.5). Estimated median DOR per ICR was 16.7 months (95% CI, 9.8-not evaluable). Disease control rate was 63.0% (95% CI, 48.7-75.7) per ICR and 70.4% (95% CI, 56.4-82.0) per INV. Median OS was not reached. Median PFS per ICR was 8.3 months (95% CI, 4.2-15.9). The most common treatment-related adverse events were fatigue (37.0%), diarrhea (14.8%), pruritus (13.0%), hyperthyroidism (9.3%), and arthralgia (9.3%) as well as hypothyroidism, asthenia, constipation, and maculo-papular rash (7.4% each). There were no treatment-related deaths. Conclusions: Cemiplimab provided clinically meaningful antitumor activity, including durable responses, and an acceptable safety profile in patients with mBCC who had progressed on or were intolerant to HHI therapy. Citation Format: Karl Lewis, Ketty Peris, Aleksander Sekulic, Alexander J. Stratigos, Lara Dunn, Zeynep Eroglu, Anne Lynn S. Chang, Michael R. Migden, Suk-Young Yoo, Kosalai Mohan, Ebony Coates, Emmanuel Okoye, Timothy Bowler, Jean-François Baurain, Oliver Bechter, Axel Hauschild, Marcus O. Butler, Leonel Hernandez-Aya, Lisa Licitra, Rogerio I. Neves, Emily S. Ruiz, Frank Seebach, David M. Weinreich, George D. Yancopoulos, Israel Lowy, Priscila Goncalves, Matthew G. Fury. Primary analysis of phase 2 results for cemiplimab in patients with metastatic basal cell carcinoma who progressed on or were intolerant to hedgehog inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT165.

TPS3161 Background: VV1 is an oncolytic vesicular stomatitis virus engineered to express human IFNβ to enhance cellular anti-tumor immune responses and tumor selectivity, and the human sodium iodide symporter (NIS) for virus tracking by SPECT imaging. Cancer cells are often hyporesponsive to IFNβ, enabling the efficient spread of VV1 and resulting in increased oncolysis. Differently from other oncolytic viruses, VV1 is suitable for both intra-tumoral (IT) and/or intra-venous (IV) administration. Despite considerable anti-tumor activity with checkpoint inhibitors (CPI) among some malignancies, long term survival and overall cures remain elusive. Prior Ph 1 studies have shown significant anti-tumor activity among several malignancies when VV1 was administered either as monotherapy or in combination with a CPI, despite progression on prior CPI monotherapy. Furthermore, pre- and post-treatment biopsy evaluations after VV1 treatment have demonstrated T cell infiltration and inflammation in both IT injected and non-injected lesions. Among IV treated patients (pts), IFNβ was detectable in the serum correlating with viral replication, making it an effective biomarker. C is a high-affinity potent human IgG4 anti-PD-1 monoclonal antibody. Though approved for use in cutaneous squamous cell carcinoma, C has shown anti-tumor activity, similar to other CPI, in several other indications. Therefore, VV1 and C could be an attractive combination for the immunotherapy for several solid tumors. This study represents the first clinical evaluation of VV1 in combination with C in pts with advanced solid tumors. Methods: The Ph 2 Simon 2 stage five-arm study of IV administration VV1 in combination with IV C will enroll pts with advanced NSCLC, HCC, melanoma & endometrial cancer. Enrolled pts with NSCLC & melanoma will be recent CPI-progressors, whereas enrolled HCC & endometrial cancer will be CPI-naïve. The study’s objectives include assessment of preliminary anti-tumor activity, safety, & immuno-regulatory activity of the combination. Pts will receive IV VV1 once on D1 and IV C once every 3 weeks until confirmed disease progression or intolerable toxicity. Pts enrolled in one melanoma cohort will also receive IT VV1 administered to palpable lesions. Response will be assessed every 9 weeks per RECIST v1.1. The null hypothesis of each cohort’s ORR will be tested versus a one-sided alternative yielding a Type I error rate of 5% and power of 80%. Cohorts will be expanded based on signal of activity. Clinical trial information: NCT .