MedPacto wins FDA approval to add dosage cohort in osteosarcoma trial

MedPacto said Monday it has received FDA approval to amend its investigational new drug application to add a mid-dose cohort for vactosertib, an anticancer drug candidate currently in a Phase 2 trial.

The company is conducting a simultaneous South Korea-US Phase 2 trial of vactosertib in osteosarcoma patients. The approved amendment adds a mid-dose patient group to the ongoing study.

South Korea's Ministry of Food and Drug Safety granted the same amendment in September. The change adds a 200 mg twice-daily mid-dose cohort — or 150 mg twice daily for adolescents — alongside the existing high-dose cohort receiving 300 mg twice daily.

MedPacto said it expects the amendment to allow a more precise evaluation of the relationship between dosage and treatment response in the Phase 2 trial, and to help secure optimal efficacy data.

"In the Phase 1 trial, relatively superior treatment responses were observed in the mid-dose patient group," a company official said. "We expect this amendment will allow us to verify the optimal dose."

In the Phase 1 osteosarcoma trial, MedPacto recorded an objective response rate of 36.4 percent — including complete remission cases — more than three times higher than existing treatments. The company said it has also secured data in the Phase 2 trial that satisfy the protocol's required endpoints.

Osteosarcoma is a rare malignant bone tumor that primarily affects children, adolescents and young adults. Existing treatments have shown limited effectiveness in improving survival rates, leaving a significant unmet need for new therapies.