Long term outcome in patients with advanced malignant peritoneal mesothelioma (AbM) treated with a pemetrexed/platin combination.

Abstract

295 Background: Advanced mesothelioma is associated with a short overall-survival (OS 9-12 mo). Peritoneal mesothelioma is a rare and aggressive cancer of the peritoneum. Data on long-term outcome of AbM are rare. Pemetrexed (Pem)+cisplatinum (DDP) has been reported effectively for AbM previously with the optimal ctx duration remaining still undetermined. We evaluated the efficacy and safety of Pem + Platinum for the treatment of AbM prospectively. A part of our data has been published previously (ASCO GI 2006). This is a 10-year OS update. Methods: We analyzed the long-term OS of a cohort of AbM that started treatment between 02/2002 and 03/2006. All AbM pts received Pem (500 mg/m2) +DDP (75 mg/m2) or carboplatin (AUC 5) prospectively on d1 (repeated on d22 for 6 cycles or disease progression). Folinic acid 400 μg po/d and vit B12 1000 μg i.m. qw 9 wks was administered to prevent AE. Study endpoints were best response (CR/PR), time to progression (TTP), OS and safety. Results: A total of 95 mesothelioma pts were observed from 12/2002 until 05/2006 in a single institution. Four patients (1 AbM, 1 MPM, 2 MPM+AbM) were excluded due to renal impairment (n = 1) or death prior to chemotherapy (n = 3). Staging procedures revealed AbM in 22 patients, while this was pleural mesothelioma in 64 patients. Five additional patients had malignant mesothelioma on both sites of the diaphragm. Initial ctx was with DDP in all pts with AbM, except one who died prior to therapy initiation. Pem was administered a median of 6 cycles (range 1 –33+). Major toxicity (WHO > III/IV) was nausea and neutropenia (2/11). Benefit for AbM was observed in 77%, with objective RR in 36% while a response or stabilization was observed in 4 out 5 pts with AbM + MPM (80%). Mean time to progression was 11.5 months (range 0 to 35+) in AbM vs 15.4 pts with AbM +MPM. Mean survival was 32.6 months (range 1 to 147+ months) in AbM and 48.4 months in pts with AbM + MPM (18-146+ months). Conclusions: The natural course of AbM is different from pleural mesothelioma. Pts with an AbM had a much longer TTP and overall survival when compared to pleural mesothelioma. Pemetrexed with platinum is well tolerated and has substantial activity for malignant peritoneal mesothelioma.