Selpercatinib Loxo-292 Promising for Lung and Other “RET Fusion” Cancers

Selpercatinib is a precision cancer medicine that targets RET in some NSCLC patients.

by Dr. C.H. Weaver M.D. 6/2018

Selpercatinib (LOXO-292), a novel precision cancer medicine targeting tumors containing a mutated protein known as RET appears promising for the treatment of non-small cell lung cancer and other cancers with RET mutations.

About Selpercatinib (LOXO-292)

Selpercatinib is an oral precision cancer medicine that is designed to target cancers with genomic alterations in the RET kinase, which include fusions and activating point mutations which lead to overactive RET signaling and uncontrolled cell growth. These “RET fusions” have been identified in approximately 2% of non-small cell lung cancer, 10-20% of papillary and other thyroid cancers, and a subset of other cancers. Activating RET point mutations account for approximately 60% of medullary thyroid cancer. Selpercatinib was designed to inhibit native RET signaling as well as anticipated acquired resistance mechanisms that could otherwise limit the activity of this therapeutic approach.

In the initial clinical trial of Selpercatinib it shrank the cancer in 77% of patients with RET fusion cancers originating in the lungs, thyroid and pancreas. Overall treatment with Selpercatinib was well tolerated. According to the investigators the anti-cancer responses to Selpercatinib have been durable. None of the responding patients has relapsed to date, with the longest-followed patient still on therapy 10 months since beginning treatment.

In a more recent analyses reported in September 2019 105 patients with advanced RET fusion-positive NSCLC who had received pretreatment with platinum-based chemotherapy and were subsequently treated with selpercatinib in the LIBRETTO-001 study, the overall response to treatment was 68%. Responses were durable, with a median duration of response of 20.3 months. Ninty-one percent of NSCLC patients with measurable brain metastases responded to treatment with selpercatinib.

Selpercatinib is currently only available in clinical trials but represents a new area of development for precision cancer medicine. Loxo’s other medicine in development is larotrectinib which has already demonstrated significant anti-cancer activity in cancers with TRK gene fusions. The drug is under FDA review with an approval decision expected in late November.

References:

  1. http://abstracts.asco.org/214/AbstView_214_219841.html
  2. Drilon A, Oxnard GR, Wirth L, et al. A phase 1/2 trial of LOXO-292 in patients with RET fusion-positive lung cancers. Presented at: IASLC 2019 World Conference on Lung Cancer hosted by the International Association for the Study of Lung Cancer; September 7-10, 2019; Barcelona, Spain. Abstract PL02.08.
  3. International Association for the Study of Lung Cancer. Registrational data from the LIBRETTO-1 trial demonstrate compelling and durable activity of selpercatinib (LOXO-292) in RET fusion-positive lung cancer. Published September 9, 2019. Accessed September 9, 2019.

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