Image by Lance Liotta
AML cells
The US Food and Drug Administration (FDA) has granted orphan drug designation for PTX-200 for the treatment of acute myeloid leukemia (AML).
PTX-200, or triciribine phosphate monohydrate, is a small-molecule Akt inhibitor being developed by Prescient Therapeutics Ltd.
PTX-200 is currently being tested in combination with cytarabine in a phase 1b/2 trial of patients with relapsed or refractory AML.
PTX-200 was previously tested as monotherapy in a phase 1 trial of patients with relapsed or refractory hematologic malignancies.
Results from this trial were published in Leukemia Research in November 2013.
The trial included 41 patients who received at least 1 dose of PTX-200. The patients’ median age was 70 (range, of 23–83), and most (77%) were male.
Thirty-six patients (84%) had AML, 3 had myelodysplastic syndromes/chronic myelomonocytic leukemia (CMML), 2 had chronic lymphocytic leukemia, and 2 had acute lymphoblastic leukemia.
The patients had received a median of 2 prior therapies (range, 0–11), and they received a median of 1 cycle (range, 0–3) of PTX-200 at varying doses.
The maximum-tolerated dose of PTX-200 was 55 mg/m2. Two dose-limiting toxicities (DLTs) occurred in 3 patients in the 65 mg/m2 cohort (2 cases of lipase elevation and 1 case of triglyceride elevation).
One dose-limiting toxicity (mucositis) occurred in the 35 mg/m2 cohort. All DLTs resolved after patients stopped taking PTX-200.
Common treatment-emergent grade 3/4 adverse events included infection/febrile neutropenia (24%), bleeding (2%), mucositis (2%), and elevated lipase (5%).
Thirty-two patients were evaluable for response. There were no responses, but 17 patients had stable disease. The remaining 15 patients progressed.
Three patients with stable disease (all with AML) achieved at least a 50% reduction in bone marrow blasts, and a patient with CMML experienced spleen reduction and resolution of leukocytosis.
About orphan designation
The FDA grants orphan designation to products intended to treat, diagnose, or prevent rare diseases/disorders affecting fewer than 200,000 people in the US.
Orphan designation provides companies with certain incentives to develop products for rare diseases. This includes a 50% tax break on research and development, a fee waiver, access to federal grants, and 7 years of market exclusivity if the product is approved.
