Phase 1 dose expansion and biomarker study assessing first-in-class tumor microenvironment modulator VT1021 in patients with advanced solid tumors.

ABSTRACT

BACKGROUND: Preclinical studies have demonstrated that VT1021, a first-in-class therapeutic agent, inhibits tumor growth via stimulation of thrombospondin-1 (TSP-1) and reprograms the tumor microenvironment. We recently reported data from the dose escalation part of a phase I study of VT1021 in solid tumors. Here, we report findings from the dose expansion phase of the same study. METHODS: We analyzed the safety and tolerability, clinical response, and biomarker profile of VT1021 in the expansion portion of the phase I study (NCT03364400). Safety/tolerability is determined by adverse events related to the treatment. Clinical response is determined by RECIST v1.1 and iRECIST. Biomarkers are measured by multiplexed ion beam imaging and enzyme-linked immunoassay (ELISA). RESULTS: First, we report the safety and tolerability data as the primary outcome of this study. Adverse events (AE) suspected to be related to the study treatment (RTEAEs) are mostly grade 1-2. There are no grade 4 or 5 adverse events. VT1021 is safe and well tolerated in patients with solid tumors in this study. We report clinical responses as a secondary efficacy outcome. VT1021 demonstrates promising single-agent clinical activity in recurrent GBM (rGBM) in this study. Among 22 patients with rGBM, the overall disease control rate (DCR) is 45% (95% confidence interval, 0.24-0.67). Finally, we report the exploratory outcomes of this study. We show the clinical confirmation of TSP-1 induction and TME remodeling by VT1021. Our biomarker analysis identifies several plasmatic cytokines as potential biomarkers for future clinical studies. CONCLUSIONS: VT1021 is safe and well-tolerated in patients with solid tumors in a phase I expansion study. VT1021 has advanced to a phase II/III clinical study in glioblastoma (NCT03970447).

The network of cells that surround a tumor, the tumor microenvironment, can help cancers to grow. Therapies targeting the tumor microenvironment may help to stop tumor growth. One such therapy is VT1021. In animal models, VT1021 treatment stops tumor cells from growing by changing the tumor microenvironment. Here, we have tested VT1021 in a clinical trial and found that VT1021 treatment is safe and well tolerated in patients with cancer. We also see signs of efficacy in some patients and observe evidence that VT1021 modifies the tumor microenvironment, which may help to block tumor growth. Finally, we identified several markers from the blood that may help to predict which patients will best benefit from VT1021 treatment. With further testing in clinical trials, VT1021 may be a useful therapy for patients with cancer.