On September 20, 2021 Mirati Therapeutics, Inc. (NASDAQ: MRTX), a clinical-stage targeted oncology company, reported results from a post hoc exploratory analysis of the Phase 2 study, MRTX-500. Results showed durable responses and long-term survival with sitravatinib in combination with nivolumab (OPDIVO)1 in patients with second or third line non-squamous non-small cell lung cancer (NSCLC) who experienced clinical benefit on a prior checkpoint inhibitor (CPI) and subsequent disease progression (n=68) (Press release, Mirati, SEP 20, 2021, View Source [SID1234588016]).

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The findings (Abstract # 1191O) will be presented in an oral presentation today at 8:20 a.m. ET during the NSCLC Proffered Paper Session II at the European Society for Medical Oncology Congress (ESMO) (Free ESMO Whitepaper) 2021.

In this exploratory analysis, the median progression free survival (PFS) was 5.7 months (95% Confidence Interval, CI: 4.9, 7.6) and the median overall survival (OS) was 14.9 months (95% CI: 9.3, 21.1), with 56% and 32% of these patients alive at one year and two years, respectively. The objective response rate (ORR) was 18%, with 3% of patients achieving a complete response (CR) and 15% of patients achieving a partial response (PR). The median duration of response (DOR) was 12.8 months.

"As many as seventy percent of patients with non-small cell lung cancer have progression of their disease on or after receiving checkpoint inhibitor therapy, leaving these patients with a continued unmet medical need," said Dr. Ticiana Leal, M.D., lead study author, and faculty member at Emory University. "Targeting the TAM and VEGFR receptor tyrosine kinases has been shown to modulate the tumor microenvironment toward a less immunosuppressive state. The encouraging results presented today support combining sitravatinib with a checkpoint inhibitor to help augment the antitumor response."

The sitravatinib and nivolumab combination in this analysis was well-tolerated and consistent with what has been previously reported for this regimen in patients with non-squamous NSCLC who are CPI experienced. Grade 3/4 treatment-related adverse events (TRAEs) were reported in 66% of patients. The rate of TRAEs leading to study treatment discontinuation was 22%.

"These data reinforce the scientific rationale to combine sitravatinib with nivolumab, which in this analysis, resulted in extending overall survival in patients with non-squamous non-small cell lung cancer, or NSCLC, and compares favorably to historical results with the standard of care, docetaxel," said Charles M. Baum, M.D., Ph.D., president, founder and head of research and development, Mirati Therapeutics, Inc. "The exploratory Phase 2 results support our ongoing Phase 3 SAPPHIRE study, which is evaluating this same regimen in patients with second or third line NSCLC who are resistant to immune checkpoint inhibitor therapy, and is expected to have an interim overall survival readout in the second half of 2022."

Virtual Investor Event

Mirati Therapeutics will host a virtual Investor Event on Monday, September 20, 2021 at 8:30 a.m. ET / 5:30 a.m. PT.

Company executives will discuss:

A top-line update from the Phase 2 registrational cohort of the KRYSTAL-1 study evaluating adagrasib in previously-treated patients with KRASG12C-mutated NSCLC
Findings from the colorectal cancer (CRC) cohort of the Phase 1/2 KRYSTAL-1 study evaluating adagrasib as monotherapy and in combination with cetuximab in patients with heavily pretreated CRC harboring the KRASG12C mutation, as presented at the 2021 ESMO (Free ESMO Whitepaper) Congress
Results from the Phase 2 MRTX-500 study evaluating sitravatinib combined with nivolumab in patients with non-squamous NSCLC who progressed on or after prior checkpoint inhibitor therapy, as presented at the 2021 ESMO (Free ESMO Whitepaper) Congress
Investors and the general public are invited to register and listen to a live webcast of the event through the "Investors and Media" section on Mirati.com. A replay of the event will be available shortly after the conclusion of the event.

About MRTX-500

MRTX-500 (NCT02954991) is an open-label, parallel Phase 2 study evaluating the tolerability and clinical activity of sitravatinib in combination with nivolumab in patients with locally advanced, unresectable or metastatic non-squamous non-small cell lung cancer (NSCLC) who have experienced progression of disease on or after treatment with a checkpoint inhibitor (CPI). Patients received oral sitravatinib once daily (QD) in combination with nivolumab 240/480 mg intravenously every 2/4 weeks, as continuous 28 day cycles. The primary endpoint was objective response rate as defined by RECIST 1.1. Secondary endpoints included safety, tolerability, duration of response, progression free survival, and overall survival.

About Sitravatinib

Sitravatinib is an investigational spectrum-selective kinase inhibitor that potently inhibits receptor tyrosine kinases (RTKs), including TAM family receptors (TYRO3, Axl, Mer), split family receptors (VEGFR2, KIT) and RET. Sitravatinib is being evaluated in combination with nivolumab (OPDIVO), an anti-PD-1 checkpoint inhibitor, in patients whose cancers have progressed despite treatment with a checkpoint inhibitor. Sitravatinib’s potent inhibition of TAM and split family RTKs may overcome resistance to checkpoint inhibitor therapy through targeted reversal of an immunosuppressive tumor microenvironment, enhancing antigen-specific T cell response and expanding dendritic cell-dependent antigen presentation. Sitravatinib is being evaluated in multiple clinical trials to treat patients who are resistant to prior immune checkpoint inhibitor therapy and progressed on platinum doublet therapy, including the ongoing potentially registration-enabling Phase 3 trial of sitravatinib in combinations with a checkpoint inhibitor in non-small cell lung cancer (NSCLC). In addition, sitravatinib in combination with checkpoint inhibitors are being evaluated in selected checkpoint inhibitor naïve patients.

For more information visit Mirati.com/science.