After nearly 3 years, FDA lifts hold on Aptose cancer drug

The FDA has lifted a clinical hold on Aptose Biosciences’ APTO-253 almost three years after it stopped the blood cancer program. Aptose is now racing to resume dosing patients with the c-Myc inhibitor in the paused phase 1b study.

Dosing in the study stopped late in 2015 following a report of a problem with an infusion pump. That led to the discovery of irregularities with the manufacturing documentation and a solubility problem. After almost three years of work, Aptose has now finished all of the tasks required to get APTO-253 back on track.

“We have optimized the drug substance manufacturing, optimized the formulation, optimized the drug product manufacturing process and have successfully manufactured multiple prototype and engineering batches of drug product,” Aptose CEO William Rice said on a quarterly conference call with investors last month.

Aptose began producing clinical supplies of the optimized APTO-253 earlier this year. In parallel, the biotech has put the drug through preclinical tests to show it is ready to return to the clinic, giving it the data to support a request for the FDA to lift the clinical hold. After taking its customary month to review the filing, the FDA has signed off on the resumption of the study.

The phase 1b was enrolling patients with acute myeloid leukemia or myelodysplastic syndrome when it came to a halt in 2015. The first step is to resume dosing patients with these conditions. Beyond that, Aptose plans to assess APTO-253 in patients with B-cell malignancies. Aptose’s interest in this population stems from recent research that implicated Myc in B-cell malignancies.

Aptose thinks APTO-253 can help various types of cancer patients by inducing cell death through the inhibition of c-Myc, an oncogene involved in cell growth and metabolism.

Shares in Aptose rose 12% in premarket trading following the release of the news. The gains added to the double-digit rise experienced by the stock since Aptose revealed it was preparing to ask the FDA to lift the hold last month.

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