Procarbazine in haematology: an old drug with a new life?

Procarbazine (PCB) was developed in the 1960s and was rapidly recognised as an active agent in lymphoid malignancies. PCB was one of the four drugs combined in mechlorethamine, vincristine, PCB, prednisolone (MOPP), one of the first combination chemotherapy regimens to show that advanced-stage disease could be cured in humans. During the last few decades, comprehensive studies have clarified cellular pathways involved in the modes of action of PCB and its drug resistance mechanisms. However, late toxicities, especially secondary leukaemias and sterility, led to its withdrawal from combination regimens used to treat Hodgkin's lymphomas (HLs). PCB was recently reintroduced in dose-intensified regimens and yielded impressive results. These new regimens (bleomycin, etoposide, doxorubicin, vincristine, PCB, and prednisone (BEACOPP) or escalated BEACOPP) are now being investigated versus the classic ABVD (doxorubicin, bleomycin, vinblastine, dacarbazine) or ABVD-like combination chemotherapy regimens in the treatment of HLs.