On June 26, 2019 Vaccibody AS reported strong immunogenicity data from the neoantigen cancer vaccine clinical trial VB N-01 (Press release, Vaccibody, JUN 26, 2019, View Source [SID1234537300]). Immunogenicity was assessed in two patients with renal cell carcinoma (RCC) and two patients with squamous cell carcinoma of the head and neck (SCCHN) after treatment with a VB10.NEO in combination with checkpoint inhibitor therapy as per protocol. Before VB10.NEO vaccination, these patients had been treated with the checkpoint inhibitor nivolumab for 12-32 months with stable disease as best response. One patient was progressing at start of vaccination. All patients had low tumour mutational burden ranging from 1.7-3.2 mutations/Mb. The top 20 neoepitopes predicted by Vaccibody’s proprietary NeoSELECTTM algorithm was selected for each of the fully personalized VB10.NEO neoantigen vaccines. Immunogenicity to each individual neoepitope has so far been assessed after 3 to 6 vaccinations of VB10.NEO by an in vitro stimulated IFN-γ ELISpot. Strong T cell responses were observed in all these first four patients tested. T cell responses were significantly increased in post-vaccination samples towards 63% of the neoepitopes. The response to the vaccine was very solid with an average increase of more than 1200 SFU per million PBMC which is on average a 250-fold increase from baseline. The breadth and the strength increased with number of vaccinations. An amplification of existing neoepitope-specific T cells as well as de novo responses were observed in all patients.
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Agnete Fredriksen President and CSO of Vaccibody, commented: We are very pleased to see the strong T cell responses observed in all of the first four patients at the initial assessments. We are excited to see that the vaccine was able to induce so strong T cell responses even in the patients with a history of many lines of previous treatment and no objective response to long-term treatment with anti-PD-1. All these first patients had low tumour mutational burden (TMB) leaving the number of mutations limited for selection of immunogenic neoepitopes, hence we believe the high percentage of the neoantigen-specific immune responses observed substantiates Vaccibody’s unique neoepitope prediction method and delivery mechanism. We are very intrigued by the de novo responses induced by the vaccine. The baseline responses and hence the number of de novo responses were surprisingly different between the patients assessed so far and we are looking forward to characterizing the T cells in more detail and follow the clinical responses in these patients