Biochemical Engineering of Cancer Immunotherapeutics

Despite the success of modern surgical techniques and chemotherapeutic strategies in treating primary tumors, the insidious process of cancer metastasis remains the most elaborate barrier to overcome in the cure of the disease. With accumulating evidence of inflammation underpinning metastatic progression, the integration of engineering fundamentals with biochemistry, biomaterials and molecular biology as it pertains to the inflammatory mediators of cell migration in immunity and metastasis is essential to cancer therapeutic development.

Cancer metastasis is a highly coordinated process in which cancerous cells "hijack" the homing mechanisms of immune cells in order to invade and colonize distant tissues. Selectins facilitate this process by mediating specific interactions between selectin-expressing immune and vascular cells and selectin ligands presented by tumor cells. My research led to the discovery of new surface adhesion molecules CD44v, carcinoembryonic antigen (CEA), and podocalyxin-like protein (PCLP), which are glycoproteins irregularly expressed by metastatic cells and function as selectin ligands in dynamic shear environment of the vasculature. Furthermore, we characterized and correlated the efficiency of selectin binding activity with their "metastatic-glycan fingerprint". Stable, specific knockdown of CD44v and CEA mediated by siRNA led to a significant reduction in interactions between colon carcinoma cells and immobilized selectins, implicating these molecules in metastases-targeting therapeutic applications.

Contemporary therapies to combat metastases increasingly focus on harnessing the immune system. However, methods to elicit potent adaptive immune responses that are cancer cell-specific yet safe remain elusive. Hence, I am currently applying engineering fundamentals to the development of cancer immunotherapeutics using a nanobiotechnology approach for optimal lymphoid tissue targeting and adjuvancy. First, using a mouse model of impaired fluid drainage and immune cell migration, we establish that delivery of antigen to the lymph node is crucial for efficient humoral but not T cell immunity in response to vaccination as well as to the process of toleragenesis. These data implicate that optimal priming of cancer specific cytotoxic T cells may be achieved via splenic targeting of cancer vaccines while strategies to reverse tumor tolerance should target the lymph nodes. Next, accumulating evidence suggests that complement is an important regulator of adaptive immune responses to vaccination as well as tumor immunity. Harnessing the inherent biochemistry of polymeric nanoparticle surfaces, activation and regulation of complement is achieved such that we might exploit its immunological functions for use in material-based vaccines. Indeed, immunization of mice with OVA-conjugated nanoparticle with surface chemistries that induce efficient complement opsonization enhanced anti-OVA immune responses. Cumulatively, these studies underscore how rational design of targeting strategies and biomaterial properties are fundamental to the development of effective immunotherapeutic strategies.

1.    Thomas, S.N., van der Vlies, A.J., O'Neil, C.P., Yu, S.S., Giorgio, T.D., Swartz, M.A., Hubbell, J.A., Engineering complement activation on polypropylene sulfide vaccine nanoparticles. Submitted to Biomaterials.

2.    Thomas, S.N., Rutkowski, J.M., Pasquilier, M., Kuan, E., Alitalo, K., E, Randolph, G., Swartz, M.A., Weak humoral immunity and acquired autoimmunity in mice with impaired dermal lymphatic drainage. Submitted to Journal of Clinical Investigation.

3.    Thomas, S.N., Swartz, M.A., Hubbell, J.A. Chemotherapeutic-loaded nanoparticles as vaccine adjuvants. In preparation.

4.    Velutto, D., Thomas, S.N., Simeoni, E., Swartz, M.A., Hubbell, J.A. Mixed micelles as 30 nm Nonviral DNA Vectors: Design and Demonstration in Tumor Microenvironment Modulation and Immunotoxicity. In preparation.

5.    Dallas, M., Liu, G., Thomas, S.N., Huso, D., Konstantopoulos, K. Divergent roles of CD44 and CEA in cancer metastasis. In preparation.

6.    Konstantopoulos, K., Thomas, S.N. Hematogenous Metastasis: Roles of CD44v and Alternative Sialofucosylated Selectin Ligands. Advances in Experimental Medicine and Biology: Molecular Immunology of Complex Carbohydrates 3. In Press.

7.    Hubbell, J.A., Thomas, S.N., Swartz, M.A., 2009. Materials engineering for immunomodulation. Nature, 462 (7272): 449-460.

8.    Thomas, S.N.*, Tong, Z.Q.*, Stebe, K., Konstantopoulos, K. 2009. Identification, characterization and utilization of tumor cell selectin ligands in the design of colon cancer diagnostics. Biorheology. 46:207-25. *Equally contributing.

9.    Konstantopoulos, K., Thomas, S.N. 2009. Cancer Cells in Transit: The Vascular Interactions of Tumor Cells. Annual Review of Biomedical Engineering. 11:177–202.

10. Thomas, S.N., Schnaar, R.L., Konstantopoulos, K. 2009. Podocalyxin-like protein is an E-/L-selectin ligand on colon carcinoma cells: Comparative biochemical properties of selectin ligands in host and tumor cells. Am J Physiol Cell Physiol. 296: C505-C513.

11. Thomas, S.N., Zhu, F., Schnaar, R.L., Alves, C.S., Konstantopoulos, K. 2008. Carcinoembryonic antigen and CD44 variant isoforms cooperate to mediate colon carcinoma cell adhesion to E- and L-selectin in shear flow. Journal of Biological Chemistry 283(23): 15647-55.

12. Alves, C.S., Burdick, M.M., Thomas, S.N., Pawar, P., Konstantopoulos, K. 2008. The Dual Role of CD44 as a Functional P-selectin and Fibrin Counter-receptor. Am J Physiol Cell Physiol 294(4): C907-16.

13. Napier, S.L., Healy, Z.R., Schnaar, R.L., Konstantopoulos, K.  2007. Selectin ligand expression regulates the initial vascular interactions of colon carcinoma cells: the roles of CD44v and alternate sialofucosylated selectin ligands. Journal of Biological Chemistry 282(6); 3433-3441. (Noted as recommended reading and a paper of special interest: Taylor, M. E., Drickamer, K. 2007 Current Opinion in Cell Biology 19: 572-577.)

14. Hanley, W., Napier, S., Burdick, M.M., Schnaar, R., Sackstein, R., Kostantopoulos, K. 2006. Variant isoforms of CD44 are P- and L-selectin ligands on colon carcinoma cells. FASEB J. 20(2): 337-9.

15. Ahn, K.C., Jun, A.J., Pawar, P., Jadhav, S., Napier, S., McCarty, O.J., Konstantopoulos, K. 2005. Preferential Binding of Platelets to Monocytes over Neutrophils Under Flow. Biochem Biophys Res Commun. 1;329(1): 345-55.

16. Cantor, R.M., Yuan, J., Napier, S., Kono, N., Grossman, J.M., Hahn, B.H., Tsao B.P. 2004. Systemic Lupus Erythematosus Genome Scan:  Support for Linkage at 1q23, 2q33, 16q12–13, and 17q21–23 and Novel Evidence at 3p24, 10q23–24, 13q32, and 18q22–23. Arthritis and Rheumatism. 50: 3203-3210.

17. Cantor, R.M., de Bruin, T., Kono, N., Napier, S., van Nas, A., Allayee, H., Lusis, A.J. 2004. Quantitative Trait Loci for Apolipoprotein B, Cholesterol, and Triglycerides in Familial Combined Hyperlipidemia Pedigrees. Arterioscler Thromb Vasc Biol. 24: 1935-1941.