HOOKIPA Pharma Inc. announced updated Phase 1 clinical, biomarker and translational data on HB-200 as a monotherapy in heavily pretreated patients with recurrent/metastatic Human Papillomavirus 16-positive (HPV16+) head and neck cancer. The data show HB-200 monotherapy induced robust, high-quality and durable tumor-specific T cell responses, which showed a trend of clinical benefit measured by a 44% disease control rate in a difficult-to-treat patient population. The data were presented in a poster presentation at the 2023 Society for Immunotherapy of Cancer (SITC) Annual Meeting.

HB-200 Phase 1 biomarker results (NCT04180215): As of March 31, 2023, 93 patients with HPV16+ recurrent/metastatic cancer were treated in the Phase 1 trial of HB-200. The goal of the trial was to determine the recommended dose for further evaluation in a Phase 2 study. All patients were heavily pretreated with a median of 3 prior therapies (range 1-11).

Biomarker and translational data results: HB-200 demonstrated a robust increase in tumor-specific CD8+ T cells in all evaluable patients with HPV16+ head and neck cancers. These results are from intracellular staining of blood samples from 35 patients across all four dose levels tested in Phase 1. An analysis of 29 of these patients?treated at either the recommended phase 2 dose (RP2D) or RP2D-1?showed that T cell increases were rapid and sustained for at least 8 months, and T cell function improved over time with repeat dosing. Quantity and quality of T cells are considered important for tumor infiltration and subsequent tumor control.

Importantly, paired biopsy data suggest an association between the induction of robust, high-quality, tumor-specific T cells after HB-200 treatment and best overall response. Paired biopsy data from 13 heavily pretreated patients show that patients who achieved disease control after treatment with HB-200 monotherapy generally had greater CD8+ T cell infiltration in tumors and the tumor microenvironment compared to patients with a best overall response of disease progression. Additional Phase 1 data: The poster presentation also includes updated clinical activity and safety data from the Phase 1 study.

As of the August 7 data cut-off, there were 27 evaluable patients with HPV16+ head and neck cancers who received HB-200 at the at RP2D or RP2D-1. Among these difficult-to-treat patients, HB-200 demonstrated a 44% disease control rate, with 1 confirmed partial response and 11 patients with stable disease. While overall survival is still maturing, median overall survival is approximately 13 months, with a median follow-up period of 6.3 months. Phase 1 data also consistently demonstrate that HB-200 was generally well tolerated among 93 patients treated across all dose-level cohorts.

Treatment-related adverse events grade 3 or above were reported in 11.8% of patients (n=11), while those leading to treatment discontinuation were reported in only 2.2% of patients (n=2). This favorable tolerability profile highlights the potential of HB-200?and arenaviral immunotherapies in general?to be safely combined with other immunotherapies.