MedPacto has filed an amendment to the investigational new drug (IND) application for its Phase 1/2 clinical trial of 'Vactosertib' monotherapy in patients with relapsed, refractory, or progressive osteosarcoma with the U.S. Food and Drug Administration (FDA). The filing was made on the 18th.

The amendment is intended to determine the optimal dose by exploratorily comparing the efficacy and safety of Vactosertib at 200mg BID (twice daily) versus 300mg BID.

The trial is an open-label, multicenter Phase 1/2 clinical study conducted in the United States, evaluating the safety, tolerability, pharmacokinetics, and antitumor activity of Vactosertib monotherapy in adolescent and adult patients with relapsed, refractory, or progressive osteosarcoma. The trial site is University Hospitals Rainbow Babies & Children's Hospital at Case Western Reserve University.

In Phase 1, the safety and tolerability of Vactosertib will be evaluated, including determining the maximum tolerated dose (MTD) and recommended Phase 2 dose (RP2D) based on the occurrence of dose-limiting toxicities (DLT). In Phase 2, the antitumor activity of the monotherapy will be evaluated, and the association between biomarkers and clinical benefit will be analyzed in each dose cohort.

The trial size is a minimum of 9 adults and up to 9 adolescents in Phase 1, and a minimum of 42 adults and adolescents per dose group in Phase 2. The first participant enrollment date was May 1, 2023, and the estimated completion date is 3 months after last subject enrollment (LSI).

MedPacto stated through investment risk disclosures that the probability of an investigational drug ultimately receiving approval as a medicine is statistically known to be around 10%. It also explained that the clinical trial and product approval process may yield results that fall short of expectations, and that commercialization plans may accordingly be changed or abandoned.