Real Response in Mesothelioma

CHICAGO, IL-Physicians presenting clinical data at the Malignant Mesothelioma Conference, hosted by the University of Chicago, echoed one and other with a recurring theme--while the past has offered little in the way of advancements in surgical, radiotherapy, and chemotherapy, new active drugs and insights into the biology of mesothelioma are demonstrating real progress, helping to replace longstanding nihilism that had been associated with the treatment of this disease.

Antifolates, such as premetrexed disodium (Alimta), offer new hope for effective treatments, as illustrated by the results of a phase II single agent trial of alimta, in which a confirmed partial response was seen in 14.5% (9/62) of advance pleural mesothelioma patients. In this study, 62 chemonaive patients were enrolled with a 5.2:1 M/F ratio, median age of 67 years (range 40-80) stage III/IV disease (31%/54%), and subhistology of epidermal (74%), mixed (14%), or sarcamatoid (9%) involvement.

The median duration of response was +10.8 months, median time to progressive disease, 5.4 months, and median survival was 10.7 months. Hematologic toxicities were observed as grade 3 and 4 neutropenia in 14% of patients, and grade 3 thrombocytopenia in 1.7% of patients. At present, the most common non-hematological toxicity observed in patients included fatigue (10.9%), anorexia (5.9%), nausea (4.8%), and febrile neutropenia (4.8%)--only 1% of patients experienced grade 4 non-hematological toxicities.

Previous to this study, investigators found that vitamin supplementation with low-dose folic acid and vitamin B12 was capable of markedly reducing toxicity previously seen with alimta therapy. Accordingly, this phase II single agent trial of alimta included vitamin supplementation to help alleviate anticipated toxicities. With regard to folic acid and B12 supplementation, partial response results were 18% (5/40) for fully vitamin supplemented patients, 60% (3/5) for partially vitamin supplemented patients (patients who started supplementation after cycle one), and 5% (1/17) for non-vitamin supplemented patients.

Axel Hanauske, MD, Medical Director, Eli Lilly & Company presented results from an overall comparison of observed toxicities before and after the addition of vitamin supplements to alimta studies, in which 246 patients from 12 studies received no vitamin supplements and 78 patients from 3 studies received folic acid and vitamin B12 supplements. After adding vitamin supplementation to alimta trials, a dramatic decrease was seen in both hematologic and non-hematologic toxicities (37% before vs. 6.4% after), as well as a complete cessation of drug-related deaths since the vitamin supplementation started (7% before vs. 0% after).