In December, Loxo Oncology announced that it had initiated submission of a rolling New Drug Application to the US Food and Drug Administration (FDA) for larotrectinib for unresectable or metastatic solid tumors with NTRK-fusion proteins in adult and pediatric patients who require systemic therapy and who have progressed after prior treatment or have no acceptable treatment alternative.2

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The FDA’s first tissue/site-agnostic approval was for pembrolizumab for adult and pediatric patients with unresectable or metastatic microsatellite instability–high or mismatch repair–deficient solid tumors that progress after prior treatment and have no alternative treatment options.3

“This shows that the FDA is open to this type of approval if there is a clear benefit in that context,” Dr Hong said.

The success of larotrectinib in these trials is a great example of finding a fusion or genetic alteration that is really driving particular tumors independent of histology, Dr Hong said. In contrast, however, is the experience with BRAF.

“It is known that BRAFV600E works as a target in melanoma with several drugs now approved, but in colorectal cancer it did not,” Dr Hong said. “But with NTRK is does not seem to matter what type of tumor it is, or if the tumor is in an infant or a 60-year-old. If they have this fusion driving their tumor, they respond.”


  1. Drilon A, Laetsch TW, Kummar S, et al. Efficacy of larotrectinib in TRK fusion-positive cancers in adults and children. N Engl J Med. 2018;378:731-9.
  2. Loxo Oncology initiates rolling submission of New Drug Application to U.S. Food and Drug Administration for larotrectinib for the treatment of TRK fusion cancers [news release]. Stamford, CT: Loxo Oncology; December 20, 2017. Accessed February 28, 2018.
  3. FDA grants accelerated approval to pembrolizumab for first tissue/site agnostic indication [news release]. Silver Spring, MD: US Food and Drug Administration; May 23, 2017. Accessed February 28, 2018.