Medical DevicesCytRx Reports Favorable Progress Update For Its Pivotal Phase 2 Trial With Tamibarotene As A Third-Line Treatment For Acute Promyelocytic Leukemia
CytRx Corporation (NASDAQ: CYTR), a biopharmaceutical research and development company engaged in the development of high-value human therapeutics, provided a favorable progress update for its ongoing Phase 2 STAR-1 registration clinical trial to evaluate the efficacy and safety of orally administered tamibarotene as a third-line treatment for acute promyelocytic leukemia (APL).
The primary endpoint of the open-label, non-randomized STAR-1 trial is to determine the rate of durable complete response for tamibarotene therapy when administered as a single agent to adult patients following treatment failure with all-trans-retinoic acid (ATRA) and arsenic trioxide (ATO). A durable complete response is achieved when no leukemia cells can be found in the bone marrow (morphologic leukemia-free state or MLFS), the patient"s neutrophil and platelet counts (blood cells) are increased to a certain level, and there is no sign of disease outside of the blood and bone marrow. All of these criteria must be satisfied for at least 28 days to be considered a durable complete response.
Of the 11 patients enrolled in the STAR-1 trial to date, two patients have achieved durable complete response and one has achieved MLFS, but withdrew from the trial to receive a bone marrow transplant before the durable complete response could be confirmed. One patient achieved a complete response, but did not maintain MLFS for the required 28 days to be considered a durable complete response. Another patient achieved a durable MLFS, but did not have the necessary increases in blood cells to be considered a durable complete response.
"We are highly encouraged by the trial patients" response to tamibarotene, with five of the 11 APL patients, or 45%, achieving MLFS after failing on two other drug therapies," said Steven A. Kriegsman, CytRx President and CEO. "We are aggressively working to achieve our goal of completing this trial by the end of the current year, which may include acceleration of the trial through a negotiation with the FDA regarding the total number of patients ultimately enrolled, and filing an NDA submission with the FDA in 2011."
CytRx holds the North American and European rights to tamibarotene, a rationally designed, synthetic retinoid compound designed to potentially overcome resistance to and avoid the toxic side effects of ATRA - used in the current first-line APL treatment. The STAR-1 pivotal clinical trial is being conducted under a Special Protocol Assessment (SPA) from the U.S. Food and Drug Administration (FDA). The FDA also has granted Orphan Drug Designation for the treatment of APL and Fast Track Designation for the use of tamibarotene in patients with relapsed or refractory APL. In addition, CytRx expects tamibarotene to be granted European orphan medicinal product designation for treatment of APL in the coming weeks.
Tamibarotene is approved in Japan for use in relapsed or refractory APL. The approval was based on data from two studies in Japanese patients. In the pivotal study, the effectiveness of tamibarotene was evaluated in 39 patients with APL, including patients who had never received treatment for APL and patients who had been previously treated with ATRA. The overall complete response rate in these patients was 61.5%. In patients who had a recurrence of APL following ATRA therapy, the response rate was 81%.
APL is diagnosed in approximately 1,500 new patients in the United States annually. There are currently no approved third-line treatment options for refractory APL patients, an annual market that CytRx estimates at approximately $20 million in the United States and $25 million in Europe. CytRx scientists also continue evaluating clinical strategies for developing tamibarotene as a first-line or second-line APL therapy. The estimated annual market potential in the U.S. and Europe for an expanded label including refractory, maintenance and front-line therapy is $150 million.
CytRx also retains an option to expand its licenses for the use of tamibarotene in other fields in oncology, including multiple myeloma, myelodysplastic syndrome and certain solid tumors. Tamibarotene has showed statistically significant anti-tumor activity in an animal trial for multiple myeloma, an incurable malignant tumor of the plasma cells of bone marrow.
CytRx Corporation