Sept 12 (Reuters) - Aptose Biosciences Inc APS.TO
* During a phase 1b clinical trial with APTO-253, a clinical site experienced stoppage of infusion pump during an iv infusion
* Submitted formal response to U.S. FDA regarding previously announced clinical hold of aptose's phase 1b clinical trial of APTO-253
* Says stoppage of infusion pump during an iv infusion caused by back pressure as a result of clogging of in-line filter
* During a phase 1b clinical trial with APTO-253, a clinical site experienced stoppage of infusion pump during an iv infusion
* Says co provided responses to all of questions cited in clinical hold letter issued by FDA
* Based issue with molecule
* Says now working with a drug product that does not cause filter clogging or pump stoppage
* Now working with drug product that does not cause filter clogging or pump stoppage during mock infusion studies Source text for Eikon: ID:nGNXNDAYDa Further company coverage: APS.TO