Makhloufi, Hakim

2630 Background: Human papillomavirus 16 (HPV-16) infection is associated with several cancer types with limited treatment options in the locally R/M settings. Furthermore, immune checkpoint inhibitors have limited activity against advanced HPV-cancers. TG4001 is a viral vector vaccine targeting HPV E6 and E7 antigens. We have previously shown in a single-arm, dose finding phase 1 study that TG4001 combined with PD-L1 blockade using avelumab was safe and associated with a response rate of 22%. Herein we report preliminary data on immunogenicity and clinical activity of TG4001 in a randomized phase 2 study comparing TG4001 plus avelumab versus avelumab alone. Methods: Eligibility criteria: R/M HPV16+ anogenital cancer including cervical, vulvar, vaginal, penile, and anal cancers; immunotherapy naïve and with no more than one prior line of chemotherapy. HPV-16 positivity was required and centrally determined using a PCR based assay. Patients were randomly assigned 1:1 to receive either TG4001 plus avelumab (Vaccine arm) or avelumab alone. Randomization was stratified by tumor type (cervical, anal, genital). TG4001 was administered s.c at 5·107 pfu, Q1w for 5 weeks, then Q2w until month 6 followed by Q12w until progressive disease and avelumab i.v at 800 mg Q2w until progressive disease. PBMCwere collected at baseline, day 43 and day 85 to assess T-cell responses against E6 and E7 antigens using ex-vivo IFNg ELISPOT and immunophenotyping of circulating T cells. Vaccine immune response (IR) was defined as onset of a new T-cell response against either antigen or amplification of a pre-existing response under treatment. Tumor response was assessed using RECIST 1.1. Results: 59 pts had been randomized by the time of data cut-off. IR was assessed in 24 pts in the vaccine arm and 16 pts in the avelumab arm. T cells against E6 or E7 antigens at baseline were rare with only 4 pts having a low intensity ELISPOT readout against either target prior to initiation of treatment. 11/24 pts in the vaccine arm had an IR, while none of the patients in the avelumab arm had an IR. Occurrence of IR was detected at day 43 and tended to gain in intensity at D85. In the vaccine arm, IR was associated with tumor response with 3 clinical responders among 11 pts with positive IR versus 1 response observed among the 13 patients without IR. Conversely, only 2 progressive disease pts among 11 positive IR compared favorably to the 6/13 vaccine arm pts with no IR. Remarkably, a complete clinical response was observed in a vaccine treated pt exhibiting the strongest E6 and E7 IR. Conclusions: TG4001 can induce a de novo immune response against HPV-16 antigens E6 and E7 in advanced HPV-16 cancers. The data suggest that these IRs are associated with anti-tumor response and that TG4001 vaccination in combination with ICI has the potential to drive clinical benefit in R/M anogenital cancers. Clinical trial information: NCT03260023 .

Abstract Background: Immune checkpoint inhibitors targeting the PD1/PD-L1 axis have made a breakthrough in advanced solid tumors, leading to improved overall survival (OS) in several cancer types. However, only a minority of patients experience durable responses, requiring further development of anti-tumoral immunotherapies to overcome tumor immune escape. We hypothesized that priming the immune system with TG4001, a vaccine using the highly attenuated Modified Vaccinia virus Ankara as vector expressing the HPV16 E6 and E7 proteins (rendered non-oncogenic) and interleukin-2, would increase the clinical benefit associated with PD-L1 blockade in HPV16+ cancer patients. In the single-arm part of the trial evaluating the combination of TG4001 and avelumab in terms of response rate, the overall response rate (ORR) was 22%. Presence of liver metastases had a profound impact on outcome in terms of ORR and Progression Free Survival (PFS). In patients (pts) without liver metastases an ORR of 32% was observed versus 0% in pts with liver metastases, warranting further development of this combination in this patient population (SITC 2020, Abstract ID 793). Methods: We have designed a randomized open-label two-arms trial evaluating the efficacy of the combination of TG4001 and avelumab versus avelumab alone (NCT03260023). Eligible pts have R/M HPV-16 positive anogenital cancer including cervical, vulvar, vaginal, penile, and anal cancers with no more than one prior line of chemotherapy for R/M disease and no previous exposure to cancer immunotherapy. HPV-16 positivity is determined in a central laboratory. Patients are randomly assigned 1:1 to receive either TG4001 plus avelumab or avelumab alone. Randomization is stratified by primary tumor type (cervical, anal, genital). TG4001 is administered subcutaneously (SC) at 5 × 107 plaque forming units (pfu) Q1w for 5 weeks, Q2w until month 6 and Q12w until progressive disease and avelumab intravenously (IV) at 800 mg Q2w until progressive disease. A total of up to 140 pts are currently being recruited into two cohorts (A and B) in France, Spain, and USA. For Cohort A, consisting of pts without liver metastases at Baseline (BL), a 2-stage sample size adjustment design is used with PFS by RECIST 1.1 as primary endpoint. Plans are to accrue 120 patients following Interim Analysis and Independent Data Monitoring Committee (IDMC) review. Cohort B recruits pts with liver metastases at BL. To be eligible, hepatic disease is restricted in terms of extent and number of lesions. A total of 20 pts will be recruited and analyzed for the percentage of early progressors. Secondary endpoints include overall survival, objective response rate according to RECIST1.1, duration of response, disease control rate. Exploratory endpoints comprise analyses of blood-based parameters and tumor-based proteins and RNA expression and their impact on clinical outcomes. Citation Format: Christophe Le Tourneau, Frédéric Rolland, Amaury Daste, Philippe Cassier, Sébastien Salas, Luis Manso Sánchez, Gerardo Colon-Otero, Lauriane Eberst, Olivier Lantz, Ana Lalanne, Annette Tavernaro, Hakim Makhloufi, Kaïdre Bendjama, Maud Brandely, Jean-Pierre Delord. A randomized phase II trial of TG4001 plus avelumab versus avelumab alone in recurrent/metastatic (R/M) human papilloma virus (HPV)-16 positive anogenital cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT045.