Aptose Biosciences Inc. a clinical-stage company developing new therapeutics and molecular diagnostics that target the underlying mechanisms of cancer, announced today that it has submitted a formal response to the U.S. Food and Drug Administration (FDA) regarding the previously announced clinical hold of Aptose’s Phase 1b clinical trial of APTO-253 in patients with hematologic cancers.  Aptose provided responses to all of the questions cited in the clinical hold letter issued by the FDA.

“This submission represents months of disciplined labor to resolve a manufacturing matter related to APTO-253 that arose during our Phase 1b Trial in patients with AML and high-risk MDS,” commented Dr. William G. Rice, Chairman, President and Chief Executive Officer. “Although the FDA will make the ultimate decision whether our clinical trial may resume, all of their questions have been addressed.” 

During a Phase 1b clinical trial with APTO-253, a clinical site experienced stoppage of the infusion pump during an IV infusion caused by back pressure as a result of clogging of the in-line filter. The Company determined the root cause was a chemistry-based issue with the molecule, and the Company is now working with a drug product that does not cause filter clogging or pump stoppage during mock infusion studies performed to confirm the acceptability of the updated product through the clinical infusion procedures. Such improvements to the APTO-253 manufacturing process required to address the filter clogging event will be incorporated into a Chemistry, Manufacturing and Control (CMC) amendment to our Investigational New Drug application.

For further information, please visit www.aptose.com.