PROPEL, a multicenter phase II open-label study—the largest prospective clinical trial in patients with relapsed or refractory peripheral T-cell lymphoma—found that the investigational chemotherapy agent pralatrexate produces complete responses (disappearance of all signs of cancer) in patients who had previously failed an average of three treatment regimens, including an autologous stem cell transplant for some patients. Designed to be selectively transported into tumor cells, the novel antifolate pralatrexate accumulates to high concentrations in the tumor cell, inhibiting DNA synthesis, said Owen A. O’Connor, md, phd, Columbia University Medical Center, New York, at the ASH meeting (abstract 261).
A total of 115 patients were enrolled into this single-arm, nonrandomized investigation and received weekly intraveneous infusions of pralatrexate (30 mg/m2) for 7 weeks. All patients also received vitamin B12 and folic acid throughout the study in order to prevent potential side effects of the pralatrexate. The primary endpoint of the study was the objective response rate, including all patients who had some response of their disease to therapy. Secondary endpoints included duration of response, progression-free survival, and overall survival.
Interim data of the first 65 evaluable patients showed that 29% of patients responded to treatment, with 11% experiencing a complete response and 18% experiencing a partial response. The most common severe (grade 3/4) side effects associated with pralatrexate were thrombocytopenia (31%), mucositis (14%), anemia (12%), and neutropenia (11%).