Loxo Oncology Announces Larotrectinib Update In Patients With TRK Fusion Cancers

(RTTNews) - Loxo Oncology, Inc. (LOXO) and Bayer AG announced updated clinical data for larotrectinib, an investigational oral, selective, and CNS-active TRK inhibitor, in adult and pediatric patients with TRK fusion cancers. The update included approximately one year of additional follow-up for the 55 patients described in the larotrectinib New England Journal of Medicine publication from February 2018.

In addition, the update included data for an additional 67 patients who were subsequently enrolled across the larotrectinib development program. As of a data cut-off date of July 30, 2018, median duration of response (DOR) had not been reached in either dataset.

Loxo Oncology and Bayer are engaged in a collaboration for the development and commercialization of larotrectinib. The U.S. Food and Drug Administration (FDA) has accepted the New Drug Application submitted by Loxo Oncology, and granted Priority Review for larotrectinib for the treatment of adult and pediatric patients with locally advanced or metastatic solid tumors harboring a neurotrophic tyrosine receptor kinase (NTRK) gene fusion.

The FDA has set a target action date of November 26, 2018, under the Prescription Drug User Fee Act (PDUFA). Bayer has submitted a Marketing Authorization Application (MAA) in the European Union (EU) and additional filings in other markets are underway.

The 122-patient integrated dataset included both adult and pediatric patients, who ranged in age from one month to 80 years and carried 24 unique TRK fusion-positive tumor diagnoses. Tumor types included 10 distinct soft tissue sarcomas, salivary gland, infantile fibrosarcoma, thyroid, lung, melanoma, colon, gastrointestinal stromal tumor (GIST), breast, bone sarcoma, cholangiocarcinoma, carcinoma of unknown primary, congenital mesoblastic nephroma, appendiceal, and pancreas cancers.

In the primary dataset, the overall response rate (ORR) was 80% (44/55) (95% CI: 67-90%), with a 62% partial response rate and an 18% complete response rate. In the supplementary dataset, the ORR was 81% (44/54) (95% CI: 69-91%), with a 65% partial response rate and a 17% complete response rate.

Across both datasets, the ORR was 81% (88/109) (95% CI: 72-88%), with a 63% partial response rate and 17% complete response rate. The ORR analyses for the supplementary and integrated datasets included nine patients with unconfirmed partial responses awaiting confirmatory response assessments, but did not include 13 patients who were awaiting an initial response assessment and continuing on study.

Median duration of response (DOR) had not been reached in either the primary dataset or supplementary dataset, with median follow-up of 17.6 months and 7.4 months, respectively. In the primary dataset, Kaplan-Meier landmark analyses improved since the July 2017 data cut-off date. At 6 months, 88% of responses were ongoing (83% based on the July 2017 data cut-off date). At 12 months, 75% of responses were ongoing (71% based on the July 2017 data cut-off date). Kaplan-Meier landmark analyses of the supplementary dataset were highly concordant with the primary dataset. At 6 months, 93% of responses were ongoing and at 12 months, 81% of responses were ongoing.