Department of Pharmacology and Therapeutics
Roswell Park Cancer Institute
Elm and Carlton Streets
Buffalo NY USA 14263
Tel: 716 - 845 - 3314 (Mihich)
Fax: 716 - 845 - 8857
Email: enrico.mihich@roswellpark.org

Program
Immunomodulation; Cytokines

This laboratory is developing treatments in which the host’s defenses are essential for the achievement of the cancer therapeutic or preventive goals. At this time, three projects comprise the program of this laboratory, namely: 1) studies to completely characterize the immunomodulatory action of doxorubicin (DOX, Adriamycin) by itself and when it is combined with prolonged administrations of a cytokine in inducing host-dependent effective therapies, 2) the study and characterization of a unique protein, discovered in this laboratory, which inhibits TNF mediated cytotoxicity, and 3) the study of the immunopreventive effects of immunomodulating natural products, anticancer drugs and cytokines.

The efficacies of most currently employed cancer treatment protocols are limited by poor selectivity of antitumor action and the emergence of resistant tumors. These protocols, are generally suppressive to host defense mechanisms. However, this laboratory has demonstrated that some of the chemotherapeutic agents used in these protocols can be immunoaugmenting as well as immunosuppressive, depending on conditions, and that this immunomodulatory activity can be exploited therapeutically.

Augmented host defenses can be highly selective for tumors and are, generally, equally effective against drug sensitive and resistant tumors. The effector cell types which have antitumor activities are from both the highly specific MHC restricted and the innate, non-MHC restricted, immune systems. Prevention of tumor onset and early progression may be achieved through an augmentation of innate and/or adaptive immunity by immunomodulating agents, thus bypassing the tumor antigen requirements of vaccination and other types of immunoprevention.

The research program of this laboratory has demonstrated that:

1. anticancer drugs can exert immunomodulating activity,
2. when such agents are used, under conditions resulting in immunomodulation, in combinations with certain cytokines complete tumor eradication can be achieved,
3. mice “cured” by such combination therapies not only survive a normal life span but retain the capacity to recognize and eradicate reimplanted primary tumor even after their alloimmune responsiveness has undergone senescence,
4. the action of TNF can be modulated by a newly discovered protein,
5. a mushroom-derived natural product with immunoaugmenting action may induce a measure of prostate cancer prevention.

Progress

Therapeutic exploitation of DOX-induced Immunomodulation in Combination with Certain Cytokines. The curative effects of moderate non-toxic doses of DOX in combination with prolonged treatments with low non-toxic doses of IL2 or TNF in C57BL/6 mice with EL4 lymphoma are the consequence of the antitumor effects of T cells. Therapeutic effects analogous to these found in C57BL/6 mice with EL4 were also seen in mice with E0771 mammary carcinoma. Comparisons of effector functions elicited in the EL4 and E0771 models indicated that, in contrast to EL4, E0771 cells stimulate the development of suppressor functions. Moreover, in the E0771 model stimulation of NK cells preceded that of CD8+ T cells and appeared to play a role in the therapeutic effects seen. The questions of the precise nature of these functions, their relation to the DOX plus IL2 treatment, the dependence of their stimulation on specific tumor or on a tumor type (i.e. carcinoma versus lymphoma) and their possible role in tumor escape are under study. Studies have been initiated in the E0771 tumor model to identify marker of tumor response which may eventually be used clinically. To this end, mice from several experiments were sacrificed either late in treatment (days 26-41) or following demonstration of anti-E0771 immune memory. Sera from the sacrificed mice were analyzed by metabonomics. The metabonomic patterns determined for those with advanced disease were distinct from those receiving effective treatment or from normal controls.

Mice from a single experiment involving treatment groups with and without monoclonal antibody induced lymphocyte subset depletion were sacrificed early in treatment (day 19) and their sera were analyzed by metabonomics. Individual mice were subsequently categorized based on whether or not mice in the treatment group from which they were taken had a complete response. Response to treatment again correlated with a metabonomically determined pattern which was distinct from that seen with sera from mice of experimental groups not responding.
These results suggest that it might be possible to predict response early in treatment. Further studies are needed to confirm the ability of metabonomically determined patterns to function as surrogate end points.

Studies of the New Protein Inhibiting TNF-Cytotoxicity (TIP-B1). This laboratory identified, purified and characterized a novel tumor necrosis factor-a (TNF) inhibitory protein. When cells that are normally sensitive to TNF are incubated with TIP-B1 they become resistant to TNF-induced apoptotic cell death. We are currently examining the mechanism by which TIP-B1 inhibits TNF-induced apoptotic signal transduction, the generality of TIP-B1 protection against apoptosis and the post-translational modifications of TIP-B1 and their effect on TIP-B1 activity.

Study of the immunopreventive effects of immunomodulating natural products, anticancer drugs and cytokines. Initially the TRAMP model of prostatic cancer is being used to test the preventive activity of a mushroom-derived semi-purified preparation. Daily treatments are given ip or in the diet starting at weaning, namely, 4 weeks after birth, and the effects are being measured at 12-15, 18 and 24 weeks of age. Evaluation includes enumeration of gross tumors seen at autopsy, measurements of the weight of the prostate and histological evaluation of tumor grading as per established procedures.Results of 18 weeks evaluation indicate that the preparation has no significant effect on tumor incidence or grading, but a clear inhibition of tumor growth based on prostate weights.

Select Publications

• Mihich E, Cancer Therapeutics: Personal Experiences and Future Perspectives. Cancer Biology & Therapy 3:911-915, 2004
• Mihich E, Jaenisch, R, Meeting Report: Sixteenth Annual Pezcoller Symposium: Stem Cells and Epigenesis in Cancer, Trento, Italy, June 10-12, 2004.  Cancer Res 64:8474-8477, 2004
• Mihich E, Vesosky B, Hurwitz H, Chen Q, Wang W-C, Evans S, Terando A, Mule J, Mitchell M, Symposium-in-Writing, Cellular immunity for cancer chemoimmunotherapy (Mihich Chairman). Cancer Immunol Immunother 52:661-686, 2003
• Ujhazy P, Zaleskis G, Mihich E, Ehrke MJ and Berleth ES, Doxorubicin induces specific immune functions and cytokine expression in peritoneal cells. Cancer Immunol & Immunother 52:463-472, 2003