MedPacto said the combination of its small molecule TGF-B inhibitor, Vactosertib, plus Imatinib has not shown any safety issues and been tolerated well by all people with a desmoid tumor.
Phase 1b data was introduced at the online poster session of the American Society of Clinical Oncology (ASCO) 2020. MedPacto conducted a phase 1b/2a clinical trial to assess the safety and efficacy of its combination therapy.
According to MedPacto on Monday, seven patients participated in the study, and no dose-limiting or cardiac toxicity was reported during the study. Most patients developed treatment-related adverse events of grade 1, which were mild symptoms such as myalgia, diarrhea, or fatigue.
Desmoid tumors are a rare disease characterized by the aggressive proliferation of mesenchymal fibroblast-like cells that exhibit uncontrolled growth into adjacent structures and have a tendency for local recurrence. Only three to four in one million people develop the tumor, and no standard treatment has been approved. The overall response rate (ORR) was 28.6 percent, as two patients partially responded to the treatment. The ORR improved in the combination therapy from the relatively low response rate of Imatinib monotherapy, which ranged from 5 to 15 percent.
In the study, the desmoid tumor had not progressed in all patients for six months, resulting in a 100 percent progression-free survival (PFS) rate. The combined treatment of Vactosertib and Imatinib showed a dose-dependent curve. Previous studies reported the PFS rate of 59 to 67 percent for one year and 58 percent for three years.
MedPacto said that studies revealed that transforming growth factor-beta (TGF-B) expression has a correlation to the desmoid tumor, and its signaling activity may allow for the evasion of Imatinib's treatment effect and induce tumor development.
"Due to the favorable toxicity profile and preliminary efficacy signals of Vactosertib and Imatinib, we believe that this regimen shows great potential as standard care in patients with desmoid tumor," MedPacto said Monday.
The company added that this clinical study has significance as the combined therapy showed its safety. Treating a desmoid tumor requires a long time, which excludes cytotoxic chemotherapy or other tyrosine-kinase inhibitors with toxicity issues.
With the phase 1b clinical trial's initial result that proved the safety of the treatment, MedPacto is conducting 2a trials to further assess the safety and efficacy for desmoid tumors.
<© Korea Biomedical Review, All rights reserved.>