MedPacto Reports 36.4% Partial Response Rate in Phase 1b Osteosarcoma Trial of Becotosertib

MedPacto, an innovative new drug developer, announced on June 30 that an interim analysis of its global Phase 1b clinical trial of the anticancer drug candidate 'Becotosertib' in osteosarcoma patients showed a partial response (PR) rate of 36.4%.

This figure is more than three times higher than the objective response rate (ORR) of less than 10% seen with existing treatments for relapsed and refractory osteosarcoma.

MedPacto presented these results at the 'FACTOR Conference 2025', held in Salt Lake City, United States, from June 26 to 28. The FACTOR Conference is a leading academic event in the field of osteosarcoma research in the United States. Since 2017, osteosarcoma researchers, clinicians, and patient families have gathered annually to share research achievements and collaborate on clinical support and other exchanges.

Attendees included Kim Saerom, Head of MedPacto's US subsidiary, as well as co-researchers Alex Y. Huang, professor at Case Western Reserve University, and Dr. Kristen Vanheyst, specialist at UH Rainbow Babies and Children's Hospital. They disclosed interim clinical data and presented research findings showing that a reduction in TGF-beta levels affecting the tumor microenvironment in osteosarcoma patients has a significant impact on tumor response rates.

The trial divided 11 patients with relapsed osteosarcoma into three groups and administered different doses of 'Becotosertib' as a monotherapy, observing the outcomes. The overall PR rate was 36.4%. Notably, the PR rate in the medium- and high-dose groups was 50%, and the progression-free survival (PFS) rate at 12 months was 33%.

A MedPacto representative stated, "Becotosertib has already shown the potential to extend survival in osteosarcoma patients through compassionate use approval, and now, with its outstanding efficacy surpassing existing drugs in clinical trials, the prospects for commercialization have grown even stronger."

The representative added, "This clinical trial also attracted significant interest from global pharmaceutical companies at the recent BIO USA. We will actively pursue early commercialization for rare cancers such as osteosarcoma."

Osteosarcoma is a malignant tumor that arises in bone and cartilage. About half of all patients experience fatal lung metastasis, and current immunotherapies are largely ineffective, making the development of new treatments urgently needed.