Eli Lilly has announced positive data from the Phase I/II LIBRETTO-001 study of selpercatinib (LOXO-292) as a monotherapy in patients with rearranged during transfection (RET) fusion-positive non-small cell lung cancer (NSCLC).

Selpercatinib is an investigational, oral, selective inhibitor of native RET signalling and anticipated acquired resistance mechanisms. Lilly obtained the drug as part of its purchase of Loxo Oncology in January this year.

LIBRETTO-001’s Phase I part assessed the dose-escalation approach of selpercatinib, while its Phase II part centred on dose expansion.

The Phase II part’s primary endpoint is objective response rate (ORR) and secondary endpoints are safety, duration of response (DOR) and progression-free survival (PFS).

Primary analysis of the initial 105 participants, who previously received platinum-based chemotherapy, was conducted to support the regulatory filings of the drug.

According to the results, a 68% ORR was achieved with Lilly’s therapeutic. Patients with brain metastases had a central nervous system (CNS) ORR of 91%.

At the data cut-off date of 17 June 2019, selpercatinib led to 20.3 months and 18.4 months of median DOR and median PFS, respectively.

In addition, a safety analysis in all 531 participants indicated a favourable tolerability profile. Lilly noted that only nine patients discontinued therapy because of related toxicity.

The most common adverse events reported during the study were diarrhoea, dry mouth, fatigue, headache, hypertension, constipation and elevated liver enzymes.

Data from 34 treatment-naïve patients showed an ORR of 85%. However, median DOR and PFS were not achieved in these participants.

Lilly Oncology president Anne White said: “We’re seeing the importance of precision medicines, designed for specific patients, grow in oncology.

“The data from LIBRETTO-001 show that selpercatinib, also known as LOXO-292, represents an important new advance for patients with RET fusion-positive non-small cell lung cancer, emblematic of the kinds of new oncology medicines we hope to continue to bring forward at Lilly Oncology.”

The US Food and Drug Administration (FDA) granted breakthrough therapy designation to selpercatinib in NSCLC and thyroid cancer indications.