Telik Inc announced positive interim results from the ongoing Phase 1-2a clinical trial of its TLK199 product candidate in patients with myelodysplastic syndrome (MDS), a form of pre-leukemia.

The open label, multicenter dose escalation trial is designed to evaluate safety, pharmacokinetics, pharmacodynamics and efficacy. Twelve MDS patients had been enrolled in the dose-escalation stage of the trial at the time of interim analysis. TLK199 has been well-tolerated, and the maximum tolerated dose has not been reached.

Evidence of clinical activity has been observed in 50% of evaluable patients. All responders showed clinically significant increases in at least two of the three major blood elements (white cells, red cells and platelets), with one patient showing increases in all three elements. This patient also had a significant decrease in red cell transfusion requirements, an important clinical benefit. In addition, one patient with a particularly advanced type of MDS had a decrease in levels of pre-leukemic cells, consistent with a direct anti-proliferative effect of TLK199.

"These interim results suggest that TLK199 may act at a point in the bone marrow differentiation cycle that affects the subsequent development of all three major blood elements," said Gail L. Brown, senior vice president and chief medical officer. "Clinical activity has been seen even at the lowest dose levels, and these exciting preliminary findings are being further explored as the dose escalation continues."