US-based biotechnology firm Invivoscribe has submitted LeukoStrat CDx FLT3 mutation assay to the Pharmaceuticals and Medical Devices Agency (PMDA) to support Daiichi Sankyo’s submission for quizartinib in Japan.


Image: Myeloblasts With Auer Rods Seen In Acute Myeloid Leukemia. Photo: Courtesy of Toeytoey at

The LeukoStrat CDx FLT3 mutation assay has been developed by Invivoscribe in partnership with Daiichi Sankyo as a companion diagnostic that offers global phase 3 QuANTUM-R clinical trial (Europe, US, Asia excluding Japan) in patients with relapsed/refractory FLT3 ITD acute myeloid leukemia (AML).

The LeukoStrat CDx FLT3 mutation assay is a PCR-based, in vitro diagnostic test designed to detect internal tandem duplication (ITD) mutations and tyrosine kinase domain (TKD) mutations D835 and I836 in the FLT3 gene in genomic DNA extracted from mononuclear cells obtained from peripheral blood or bone marrow of patients with acute myelogenous leukemia.

The test includes software that interprets data, generates mutant/wildtype signal ratios for ITD and TKD mutations, and predicts response to both gilteritinib fumarate and midostaurin.

This assay can help standardize the detection of genetic mutations in the FLT3 gene as one of the most important driver mutations in AML.

Invivoscribe stated that together, QuANTUM-R clinical trial and open-label phase 2 study of quizartinib (Japan) support Daiichi Sankyo New Drug Application (NDA) to Japan’s MHLW/PMDA approval of quizartinib for treating adult patients with relapsed/refractory FLT3 ITD AML.

The submission is expected to complement Invivoscribe’s prior regulatory approvals of LeukoStrat CDx FLT3 mutation assay as an AML companion diagnostic to support midostaurin for Novartis (US and Europe), and gilteritinib fumarate for Astellas (Japan).

Astellas and Invivoscribe have also submitted applications for drug and device to the CDER and CDRH, respectively, in the US.

The submission can further establish LeukoStrat CDx FLT3 mutation assay as an international standard for comprehensive FLT3 assessment for critically ill acute myeloid leukemia patients. This CDx is widely available worldwide and can generate standardized signal ratios for both ITD and TKD mutations.

Invivoscribe CSO and CEO Jeffrey Miller said: “The LeukoStrat CDx FLT3 Mutation Assay Partial Change Approval Application submission and continuing Daiichi Sankyo partnership represent significant milestones for our company.

“We continue to welcome opportunities to partner with global pharmaceutical companies interested in developing and commercializing companion diagnostics, whether for hematologic disease or solid tumors.

“Invivoscribe remains focused on improving the quality of healthcare worldwide by providing high quality, standardized reagents, tests, and bioinformatics tools to advance the field of precision medicine.”