Nuvectis Pharma has dropped plans to develop NXP800 in ovarian cancer after tallying two unconfirmed partial responses in a phase 1b study.
NXP800, a GCN2 kinase activator, has been on shaky ground since a data drop in November revealed a lack of efficacy. Seeking to improve outcomes, Nuvectis turned its attention to a new cohort of patients who received a higher dose of the drug candidate. Thursday, Nuvectis revealed that dialing up the dose failed to have the desired effect.
The biotech gave the top dose to 17 patients with recurrent, platinum-resistant, ARID1a-mutated ovarian cancer. Data are available for 13 patients. Nuvectis reported two partial responses, neither of which has been confirmed, and three cases of stable disease.
Nuvectis’ ability to increase the dose further in pursuit of a higher response rate is constrained by safety and tolerability concerns. The biotech saw cases of grade 4 thrombocytopenia, the medical term for low blood platelet count, early in the trial. Nuvectis managed the risk by switching to intermittent dosing, but CEO Ron Bentsur admitted at a H.C. Wainwright event in May that the therapeutic window is narrow.
Bentsur said in a statement Thursday that the phase 1b provided evidence that NXP800 is biologically active in the patient population. However, an assessment of the time and resources that will be needed to advance NXP800 in the indication led the biotech to turn its attention elsewhere. Nuvectis will look at the feasibility of developing NXP800 in other settings, but for now, its focus is on NXP900.
The biotech recently completed a drug-drug interaction study of NXP900, generating evidence that the SRC family kinase inhibitor can combine with EGFR and ALK drugs. Nuvectis plans to start a phase 1b trial of NXP900 in the coming weeks.
Shares of Nuvectis fell 18% to $6.20 in premarket trading Thursday.