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Ignyta starts phase 1b basket trial of RXDX-105

Ignyta announced the selection of a recommended Phase 2 dose (RP2D) and initiation of the Phase 1b portion of its Phase 1/1b clinical trial of RXDX-105, the company's orally available, small molecule multikinase inhibitor with potent activity against such targets as RET and BRAF.

The Phase 1b portion of the study utilizes a basket design focusing on patients with solid tumors that contain molecular alterations of RET or BRAF.

"We are excited to embark on further clinical evaluation of RXDX-105 in selected, molecularly-defined patient populations through this Phase 1b clinical trial expansion," said Pratik Multani, M.D., Chief Medical Officer of Ignyta.

"In the now-completed Phase 1 dose escalation and dose finding portion of this clinical study, patients were enrolled without selection for molecular alterations. Given the performance of RXDX-105 in that setting, we now look forward to evaluating this investigational agent at the RP2D in targeted patient populations. We also look forward to providing a clinical data update on this program at an upcoming scientific conference."

About RXDX-105

RXDX-105 is an orally available, small molecule multikinase inhibitor with potent activity against such targets as RET and BRAF.

In November 2015, Ignyta announced interim results from the Phase 1 clinical trial of RXDX-105, which were presented at the 27th EORTC-NCI-AACR Symposium on Molecular Targets and Cancer Therapeutics in Boston, Massachusetts.

The dose escalation clinical trial was designed to determine the maximum tolerated dose (MTD) and/or RP2D, as well as preliminary anti-cancer activity, of single agent RXDX-105 in patients with advanced or metastatic solid tumors that were not selected based on any molecular alteration.

As of the October 26, 2015, data cut-off for the presentation, the findings showed:

A total of 41 patients with a range of solid tumors were dosed in the clinical trial;
RXDX-105 was well-tolerated;
The MTD and RP2D had not yet been determined;
Pharmacokinetic measurements showed increased exposure with increasing dose, with a half-life compatible with once-daily dosing. Dosing in the fed state appears to further increase exposure;
Exposure was reaching levels expected to be efficacious based on tumor growth inhibition in animal models of RET- and BRAF-driven tumors; and
Tumor regression was observed in six patients treated with 275 mg, including one confirmed partial response (40% reduction) in a patient with non-small cell lung cancer with a KRAS G12C mutation. Two additional patients with thyroid cancer and squamous cell lung cancer exhibited reductions of 20% and 27%, respectively. In patients with tumor regression, there appears to be an exposure/response correlation.