SEATTLE, March 4, 2013 /PRNewswire/ -- Cell Therapeutics, Inc. (CTI) (NASDAQ and MTA: CTIC) and Chroma Therapeutics Ltd. announced today that Lancet Oncology has published results from the OPAL Phase 2 study of tosedostat in elderly patients with relapsed or refractory acute myeloid leukemia (AML). Tosedostat is an oral aminopeptidase inhibitor which has been shown to deprive tumor cells of the amino acid building blocks they need to make proteins necessary for tumor cell survival. The lead author was Dr. Jorge Cortes, Professor of Medicine and Internist, Department of Leukemia, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center in Houston, Texas.
The trial showed that once-daily oral tosedostat resulted in a disease control rate of 51%. Subset analyses suggested the greatest benefit occurred in the difficult-to-treat patients with prior myelodysplastic syndrome (MDS) or those that had received prior hypomethylating therapy (HMA). Adverse events were mild, predictable and manageable.
About the OPAL StudyThis Phase 2 multicenter, randomized study evaluated the safety and efficacy of two dose regimens of tosedostat to determine an appropriate regimen for future clinical studies. The study enrolled 73 patients randomized to two treatment arms: tosedostat 120 mg once daily for six months or 240 mg once daily for two months followed by 120 mg once daily for four months. The median age of the patients was 72 years old. Prior primary induction therapy for AML included 58% of the patients treated with Ara-C plus anthracycline or other Ara-C regimens, 36% of the patients treated with HMAs and 7% of the patients treated with other regimens. Fifty-two percent had been refractory to primary induction therapy. As previously presented at the 53 rd American Society of Hematology Annual Meeting, results included:
- Overall response rate (ORR) of 22% (16/73), with 10% (7/73) achieving a complete response (CR) and 29% (21/73) of patients achieving stable disease (SD) for a disease control rate of 51%.
- High response rates were observed in patients who previously received HMAs or initially were diagnosed with MDS, with an ORR of 38% (10/26) and 37% (7/19), respectively.
- Median overall survival (OS) for patients achieving a CR was 322 days; partial response (PR) 195 days; and SD 162 days.
- Adverse events were similar between dosing groups. Tosedostat was generally well-tolerated, with the majority of adverse events of grade 1 and 2. The most common treatment-related serious adverse event was febrile neutropenia reported in 29% of patients.
"There are limited therapeutic options available for elderly patients who, after failing hypomethylating therapy, experience AML progression from MDS," said Dr. Cortes. "The novel mechanism of action and observed response rate in this completed Phase 2 study suggests that tosedostat could address this unmet medical need. We are currently conducting a Phase 2 study investigating the combination of tosedostat with azacytidine - an HMA, or low-dose cytarabine, a standard leukemia therapy in patients with relapsed or refractory AML and MDS - to determine if tosedostat would be safe and more effective when used in combination with these agents."