Combination of Perfluorochemical Emulsions and Carbogen Breathing with Cancer Chemotherapy

Abstract

Over the past ten years several laboratories have explored the use of perfluorochemical emulsions (PFCE) and carbogen (95% O₂/5% CO₂; C) or oxygen breathing as an adjuvant to radiation therapy and/or chemotherapy in solid tumor model systems. The rationale for the use of PFCE and C or oxygen breathing in this therapeutic setting is that solid tumor masses contain areas of hypoxia which are therapeutically resistant. Since x-rays and many chemotherapeutic agents require oxygen to be maximally cytotoxic and most normal tissues are well-oxygenated, the additional oxygen put in circulation by the PFCE/C should not increase the normal tissue toxicities produced by the various therapies. Several anticancer agents are dependent on oxygen to be cytotoxic, these drugs such as the iron-chelating peptide bleomycin are enhanced in antitumor activity by the coadministration of a PFCE/C. The antitumor alkylating agents especially cyclophosphamide, BCNU and melphalan show increased tumor cell killing without a concomitant increase in bone marrow toxicity when administered with PFCE/C. Enhanced activity was also observed when topoisomerase II inhibitors such as adriamycin and etoposide were co-administered with PFCE/C. Positive effects, although smaller, were observed when antimetabolites such as 5-fluorouracil and methotrexate were coadministered with PFCE/C.