Interim data from a Phase 1/1b clinical trial assessing Ignyta's (RXDX +1.6%) RXDX-105 in patients with tumors harboring RET molecular mutations showed a treatment effect. The results were presented at the EORTC-NCI-AACR Molecular Targets and Cancer Therapeutics Symposium in Munich, Germany.
56% (n=5/9) of patients RET fusion-positive cancers who had not been treated with an RET inhibitor responded to treatment, including one complete responder.
A total of 91 patients have been treated in the study, 55 in Phase 1 and 36 in Phase 1b. The safety profile has been consistent with what has been previously reported. The most common treatment-related adverse events (TEAEs) were rash (31%), fatigue (22%), diarrhea (20%), nausea (18%), hypophosphatemia (14%), vomiting (14%), muscle spasms (13%) and decreased appetite (10%).
The most common Grade 3 (severe) TEAEs were rash (9%), hypophosphatemia (7%) and ALT (liver enzyme) increase (6%). One patients experienced a Grade 3 drug reaction with eosinophilia (increase in white cells in the blood) and systemic symptoms which resolved after treatment was stopped.
Enrollment in the Phase 1b is ongoing. RET inhibitor-naive patients with RET fusion-positive tumors will remain the primary focus.
RXDX-105 inhibits a protein called BRAF which plays a key role in cell growth.
Previously: Blueprint's BLU-285 shows encouraging action in early-stage GIST study (Dec. 1)