In the search for new anticancer drugs. XXIII: Exploration of a predictive design for anticancer drugs of carbohydrates containing N-nitrosochloroethylamino, N-nitrosomethyl, and N-nitrosoaminoxyl components

The spin-labeled glucose nitrosoureas 13-16, streptozotocin (18), chlorozotocin (31), streptozotocin analogues of galactosyl 24 and mannosyl 28, and their tetra-O-acetyl derivatives 25 and 29, MCNU (Cymerin, 34), and glucamine (21) were synthesized and evaluated in vivo for their anticancer activities against the murine lymphocytic leukemia P388. Compounds 13-16, 18, 24, 28, 31, and 34 possessed activities ranging from 33 to 603% increase in life span (%ILS), whereas 21, 25, and 29 were inactive (%ILS = 9 to 10). All CD2F1 male mice treated with the most active compounds (13, 14, and 34) at 20 mg/kg were alive after 30 days, whereas all mice treated with the clinical drug streptozotocin (18) and clinically tested chlorozotocin (31) succumbed. Compounds 13-16, 18, 31, and 34 were further evaluated for their antineoplastic activity against lymphoid leukemia L1210. Compounds 13 and 34 on day 60 exhibited %ILS values of 557 and 713, respectively, as compared with %ILS values of 646 and 713 for CCNU (1) and the spin-labeled SLCNU (3), respectively. The lipophilicities of 13-16, 18, 21, 24, 25, 28, 29, 31, and 34 were determined using EPR and/or UV methods. A predictive design pattern was observed, with the most active drug (34) possessing some hydrophobic property (log P = 1.24), followed by 13 (log P = 1.87) and 14 (log P = 1.81) as the more active drugs with higher hydrophobicity than 34. The clinical drugs streptozotocin (18) and chlorozotocin (31) were distinctly hydrophilic and less active. Finally, it was concluded that various scattered results of anticancer activity in the literature can be explained by a linear correlation of activities with lipophilicities.

Synthetic analogs of antitumor drugs under development in Japan

Synthetic studies on new antitumor drugs in Japan are mainly oriented toward analogs of known active structures. In the nitrosourea area ACNU, a pyrimidine analog of CCNU, is currently under clinical investigation and has myelosuppression as a side effect Nitrosoureas with a sugar moiety are of great interest and two compounds called GANU and MCNU are now ready for phase I study in Japan. Among new alkylating agents are included a series of bis-methanesulfonate of aminoglycols, an analog of cyclophosphamide called 4-hydroperoxy-cyclophosphamide, and aziridine derivatives which include the now commercially available carbazilquinone. In the antimetabolite field cyclocytidine is an analog of arabinosyl cytosine which has been extensively studied. A newer analog called N4-behenoyl-cytosine arabinoside is now being studied experimentally. In the fluorinated pyrimidine area Ftorafur has been extensively studied and a new compound FD-1 is of interest.