Nuvalent has reported positive preliminary data from the Phase I dose-escalation part of the ARROS-1 Phase I/II clinical trial of NVL-520 in advanced ROS1-positive non-small cell lung cancer (NSCLC) and various other solid tumour patients.

The study’s Phase I dose escalation part has been designed for analysing the overall tolerability and safety of NVL-520, determining the recommended Phase II dose (RP2D), characterising the pharmacokinetic profile, and assessment of initial anti-tumour activity.

It has enrolled 35 ROS1-positive NSCLC patients who have earlier received a minimum of one prior ROS1 tyrosine kinase inhibitor (TKI) treatment.

In this portion, the participants were treated with NVL-520 across five evaluated dose levels of 25mg, 50mg, 75mg, 100mg, and 125mg once daily (QD).

The preliminary data supports NVL-520 as a potential ROS1-selective inhibitor, with low intra-cohort patient PK variability and favourable pharmacokinetics observed.

There were no treatment-related dizziness, treatment-related serious adverse events (SAEs), dose-limiting toxicities (DLTs), or adverse events leading to reductions in treatment or discontinuations.

Partial responses were observed in 48%, that is ten patients from 21 heavily pre-treated response-evaluable NSCLC patients.

Patients with ROS1 G2032R mutations also had an objective response rate (ORR) of 78%, and those with a history of central nervous system (CNS) metastases achieved 73% ORR.

Patients who received two or more previous ROS1 TKIs and one or more prior line of chemotherapy had 53% ORR and those who were previously treated with lorlatinib or repotrectinib had an ORR of 50%.

Nuvalent chief medical officer Christopher Turner said: “We are excited to present the first look at the safety and clinical activity of NVL-520 from our ARROS-1 clinical trial, which we believe supports NVL-520 as a potential, best-in-class ROS1-selective inhibitor that may be capable of overcoming the limitations of current approved and investigational ROS1 TKIs.

“Across all evaluated dose levels, NVL-520 exhibited activity in a heavily pre-treated patient population, many of whom have exhausted all available treatment options and would have been excluded from other investigational ROS1 TKI studies.”

Participants are currently being enrolled in the Phase I portion of the ARROS-1 Phase I/II trial.