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The structure-activity relationship studies of a novel series of carboxylic acid derivatives of pyridine-carboxamides as DGAT-1 inhibitors is described. The optimization of the initial lead compound 6 based on in vitro and in vivo activity led to the discovery of key compounds 10j and 17h.

Novel analogs of (-)-saframycin A are described. The analogs are shown to be potent inhibitors of the in vitro growth of several tumor cells in a broad panel and promising as leads for further optimization. The first in vivo studies in a solid tumor model (HCT-116) reveal potent antitumor activity with associated toxicity of daily administration.

Human trials on the globo H carbohydrate vaccine (see picture, KLH=the carrier protein keyhole limpet hemocyanin) show that it produces strong IgM, and in some cases IgG, responses in patients with progressive and recurrent prostate cancer. Furthermore, these antibodies not only recognize synthetic antigens, but also globo H-positive tumors in biopsy extracts and tumor tissues.

There is mounting evidence to suggest that immunization-based strategies can be used to mobilize the human immune system against specific carbohydrate antigens displayed on the surface of cancer cells. Following isolation and identification, such antigens can be administered as conjugate vaccines. The tumor-associated carbohydrate antigen KH-1 is 1 such antigen and may serve as a potential target for immunization against adenocarcinoma. However, a serious impediment to the application of a vaccine-based approach involving this antigen is that its availability from natural sources is severely limited. In order to overcome this limitation, we have developed an efficient total synthesis of this complex glycolipid. We have extended our synthesis to reach a structurally related analog in which the ceramide portion of KH-1 is replaced with an allyl substituent. These synthetic advances have led to the preparation of 2 potential vaccine constructs, each based on the conjugation of the KH-1 nonasaccharide and the carrier protein keyhole limpet hemocyanin (KLH). In 1 construct (KH-1-Et-KLH), the nonasaccharide is conjugated to KLH via a simple ethyl linkage, while in the other (KH-1-MMCCH-KLH), conjugation is mediated by a 4-(4-N-maleimidomethyl)cyclohexane-1-carboxyl hydrazide (MMCCH) cross-linker. We report here the immunological properties of these 2 constructs. Mice were immunized with either of the 2 KH-1-KLH vaccine candidates or the KH-1 ceramide, along with the immunological adjuvant QS-21. Immunization with the ceramide served as a negative control and, as expected, failed to stimulate the production of antibodies against the KH-1 glycolipid. The construct in which the KH-1 nonasaccharide is linked to KLH via a simple alkyl chain stimulated significant quantities of IgM antibodies, whereas the construct linked to KLH by MMCCH induced high titers of both IgM and IgG antibodies. Inhibition data demonstrated that antibodies generated in response to immunization with the KH-1-KLH constructs recognize not only the KH-1 antigen but also the Lewisy (Ley) antigen, which, from a structural perspective, is similar to the 4 residues located at the non-reducing end of the KH-1 nonasaccharide. Thus, the KH-1-KLH constructs elicit an immune response that successfully targets 2 adenocarcinoma markers. As assessed by FACS analysis, the antibodies raised were strongly reactive with the KH-1/Ley positive cell line MCF-7 but not with KH-1 and Ley negative melanoma cell lines. Based on the results of our study, a KH-1-KLH plus QS-21 vaccine is being prepared for clinical evaluation. © 2002 Wiley-Liss, Inc.

Immunological study of Globo-H, a breast tumor associated carbohydrate antigen, has been producing promising results. As the demand for the supply of this antigen grows, the efficient production of enough material has become an urgent problem. We have been trying to solve this problem by two approaches: the solid support synthesis of Globo-H, and the development of efficient conjugation methods. For the solid support synthesis, solution phase direct roll-over reactions have been performed to verify the possibility that this method can be used to install the 2-amino-2-deoxy galactose moiety on the polymer support. From the results of these reactions, a tumor associated nonasaccharide antigen KM-i has been synthesized. To improve the conjugation yield of Globo-H to a carrier protein KLH (keyhole lympet hemocyanin), a model study has been carried out to implement an N-hydroxy succinimide ester conjugation method. At the same time, sufficient amounts of Globo-H have been synthesized by solution phase protocol for further immunocharacterization.