US-based biopharmaceutical firm Cell Therapeutics has obtained a notification from the US Food and Drug Administration (FDA) that the partial clinical hold on tosedostat or IND 075503 has been removed and all studies underway may continue.

In June 2013, the FDA put a partial clinical hold on its study after the death of one of the patients in a clinical trial.

Tosedostat is a novel, orally administered aminopeptidase inhibitor that deprives tumour cells of the amino acid building blocks they need to make proteins necessary for tumour cell survival.

Currently there are two ongoing Phase II investigator-sponsored trials examining the clinical activity of tosedostat in elderly patients with newly diagnosed and relapsed acute myeloid leukemia (AML) and high-risk myelodysplastic syndromes (MDS) in the US and EU.

Tosedostat has demonstrated significant anti-tumour responses in blood-related cancers and solid tumours in Phase I-II clinical trials.

Principal investigator in the tosedostat first-line AML/MDS trial Dr John Pagel said: "We are pleased that the FDA has responded favorably to the tosedostat clinical trial data provided and removed the partial clinical hold to allow further development of tosedostat in ongoing and future studies."

Last month, the company reported positive interim results from an investigator-initiated Phase II trial of tosedostat in combination with cytarabine or decitabine in newly diagnosed older patients with AML or high-risk MDS.

The study achieved its primary objective with 82% patients alive at four months. Median overall survival was encouraging at approximately 12 months for both study arms.

The company has an exclusive marketing and co-development agreement with Chroma Therapeutics for drug candidate tosedostat in North, Central and South America.

Image: Bone marrow aspirate showing acute myeloid leukemia. Photo: courtesy of ToNToNi.