Design and synthesis of a cephalosporin-retinoic acid prodrug activated bya monoclonal antibody-beta-lactamase conjugate

Two novel series of all-trans-beta -retinoic acid derivatives were synthesi zed and found to possess anticancer activity. The first series, cephalospor in 3 ' -retinoic esters 6 and 7 were, respectively, obtained by the condens ation of all-trans-beta -retinoic acid (2) with cephalosporins 4 and 5. The second series, 7-(retinamido)cephalosporins 11 and 12, were synthesized, r espectively, by the condensation of 2 with cephalosporins 9 and 10. These f our heretofore undescribed compounds 6, 7, 11, and 12 showed inhibitory act ivity against murine leukemias (L1210 and P388), sarcoma 180, breast carcin oma (MCF7), and human T-lymphocytes (Molt4/C8 and CEM/0). They also inhibit ed squamous metaplasia and keratinization in tracheal or.-an cultures deriv ed from vitamin-A-deficient hamsters. Moreover, cephalosporin 3 ' -retinoic ester 7 exhibited enhanced activity against keratinization with ED50 = 3.9 1 x 10(-11) M in the presence of a beta -lactamase from Staphylococcus aure us 95. A tumor targeting fusion protein (dsFv3-beta -lactamase) was also us ed in conjunction with cephem-based retinoid 7 and the potency of 7 toward L1210, P388, and MCF7 was found to approach that of the free retinoic acid (2). In the presence of dsFv3-beta -lactamase, tumor cells were found to be much more susceptible to retinoid 7 than normal human embryonic lung cells . These notions provide a new approach to the use of beta -retinoic acid fo r antitumor therapy. (C) 2001 Elsevier Science Ltd. All rights reserved.