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Falchook Sheds Light on Rare Oncogenic Drivers in NSCLC

Angelica Welch
Published: Tuesday, Aug 28, 2018

Gerald S. Falchook, MD, MS

Gerald S. Falchook, MD, MS

Patients with mutations in NTRK, RET, MET, HER2, and KRAS G12C have limited therapeutic options, but potentially promising agents are on the horizon, said Gerald S. Falchook, MD, MS, adding that these rare oncogeneic drivers in non–small cell lung cancer (NSCLC) are beginning to be better understood.

State of the Science Summit™ on Advanced Non–Small Cell Lung Cancer, Falchook, director of Drug Development of Sarah Cannon Research Institute at HealthONE, discussed these oncogenic drivers in advanced disease.


There are 3 members in this family, Falchook explained—TRKA, TRKB, and TRKC. These are encoded by NTRK1, NTRK2, and NTRK3. TRK causes downstream activation of MAPK, PI3K, and PLCg pathways, which results in cell proliferation and increase cell survival and migration, leading to tumor growth.

In May 2018, the FDA granted a priority review to a new drug application for larotrectinib for the treatment of adult and pediatric patients with locally advanced or metastatic solid tumors with an NTRK gene fusion.


RET fusions are chromosomal rearrangements that create a fusion between RET and other proteins, activating the RET receptor as well as the MAPK and EGFR pathways. These fusions occur in about 2% of NSCLC cases—usually in patients younger than 60 years old who are never smokers or former light smokers with a poorly differentiated histology and early lymph node metastasis.

Current inhibitors in the NSCLC landscape for RET fusion–positive patients include vandetanib (Caprelsa), cabozantinib (Cabometyx), regorafenib (Stivarga), lenvatinib (Lenvima), sorafenib (Nexavar), sunitinib (Sutent), apatinib, alectinib (Alecensa), RXDX-105, BLU-667, and LOXO-292.

“There are a lot RET inhibitors in the clinic now. The first 2, vandetanib and cabozantinib, are not ‘clean’ RET inhibitors. They are multikinase inhibitors with a lot of other targets involved,” explained Falchook. “As time has gone on, more selective inhibitors have been developed.”

LIBRETTO-001 is a phase I study of LOXO-292 in patients with RET-altered cancers (NCT03157128). The potent and highly selective RET inhibitor LOXO-292 induced an overall response rate (ORR) of 77% across RET fusion–positive cancers, according to findings presented at the 2018 ASCO Annual Meeting.3 Responses were observed with RET V804M gatekeeper mutations, which Falchook said are known to cause resistance to multikinase inhibitors. Among patients with NSCLC, the ORR was 77% (95% CI, 58%-90%).

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