On November 9, 2018 Mirati Therapeutics, Inc. (NASDAQ: MRTX), a clinical-stage targeted oncology company, reported data from the ongoing Phase 2 clinical trial of mocetinostat in combination with durvalumab (IMFINZI) in non-small cell lung cancer (NSCLC) patients at the Society for Immunotherapy of Cancer (SITC) (Free SITC Whitepaper) 33rd Annual Meeting in Washington, D.C (Press release, Mirati, NOV 9, 2018, View Source [SID1234531095]). The data will be presented today in a poster and also in an oral presentation on Sunday, November 11th.

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Highlights from the Oral Presentation

The clinical trial is a Phase 2 study evaluating the efficacy and safety of mocetinostat in combination with durvalumab, an anti-PD-L1 immune checkpoint inhibitor, in patients with NSCLC who have experienced documented disease progression following prior treatment with an immune checkpoint inhibitor. As of the data cut-off date of October 2, 2018:

29 patients were evaluable for response with at least one radiographic scan. Patients had a median of two lines of previous therapy.
12/29 evaluable patients demonstrated tumor reductions.
6/29 evaluable patients demonstrated tumor reductions of greater than 30%.
5/29 evaluable patients achieved a confirmed Partial Response (PR).
4/29 evaluable patients, including 2 responding patients, remained on treatment at the time of data cut-off.
A preliminary Kaplan-Meier estimate of median duration of response was greater than 5 months.
The combination has been well-tolerated and most adverse events (AEs) were grade 1 or 2.
"The combination of mocetinostat with durvalumab demonstrated clinical benefit in this difficult to treat population of checkpoint inhibitor refractory NSCLC patients," said Charles Baum, M.D., Ph.D., President and Chief Executive Officer at Mirati Therapeutics. "While these results are promising, we have made the strategic portfolio decision to prioritize sitravatinib for further development in the treatment of checkpoint inhibitor refractory patients and plan to explore collaborative opportunities to further develop mocetinostat."

The Company recently announced plans to initiate a Phase 3 clinical trial comparing sitravatinib in combination with checkpoint inhibitor therapy to docetaxel in second line checkpoint inhibitor refractory NSCLC patients in the first half of 2019. In addition, the Company also announced plans to initiate a Phase 1/2 clinical trial of MRTX849, an oral inhibitor of KRAS G12C, in patients with NSCLC, colorectal cancer, and other solid tumors that harbor the G12C mutation. Trial initiation is planned for early 2019 after the investigational new drug (IND) allowance letter is received from the U.S. Food and Drug Administration (FDA) for the application that was filed in October 2018.

About Mocetinostat

Mocetinostat is an oral, Class I and IV selective histone deacetylase (HDAC) inhibitor. Inhibition of histone acetylation is predicted to enhance the recognition of tumor cells by anti-tumor T cells and reverse immunosuppressive factors in the tumor microenvironment. Mocetinostat is being evaluated in a Phase 2 clinical trial in combination with durvalumab (IMFINZI) in non-small cell lung cancer (NSCLC) patients who have experienced disease progression following prior treatment with a checkpoint inhibitor.

About Sitravatinib

Sitravatinib is a 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. As an immuno-oncology agent, sitravatinib is being evaluated in combination with nivolumab (OPDIVO), an anti-PD-1 checkpoint inhibitor, in patients who have experienced documented disease progression following 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 also being evaluated as a single agent in a Phase 1b expansion clinical trial emphasizing enrollment of patients whose tumors harbor specific mutations in the CBL protein. When CBL is inactivated by mutation, multiple RTKs, including TAM, VEGFR2 and KIT, are dysregulated and may act as oncogenic tumor drivers in NSCLC and melanoma. Sitravatinib potently inhibits these RTKs and is being investigated as a treatment option for cancer patients with CBL mutations.

About MRTX849

MRTX849 is an orally-available small molecule that potently and selectively inhibits a form of KRAS which harbors a substitution mutation (G12C). KRAS G12C mutations are present in approximately 14% of NSCLC adenocarcinoma patients and 5% of colorectal cancer patients. Tumors characterized by KRAS G12C mutations are commonly associated with poor prognosis and resistance to therapy, and patients with these mutations have few treatment options. MTRX849 has demonstrated broad-spectrum tumor regression in a large cohort of KRAS G12C positive, pre-clinical in-vivo human tumor models. MRTX849 demonstrated complete regression of tumors in a subset of models at well-tolerated dose levels. Early proof-of-concept clinical data is anticipated in 2019.