Combined Chemo-immunotherapy as a Prospective Strategy To Combat Cancer: A Nanoparticle Based Approach Aniruddha Roy, Manu Smriti Singh, Pramod Upadhyay,* and Sangeeta Bhaskar* Product DeVelopment Cell-I, National Institute of Immunology, New Delhi, 110067, India Received May 6, 2010; Revised Manuscript Received July 29, 2010; Accepted September 1, 2010 Abstract: The prime objective of this study was to develop a combined chemo-immunothera- peutic formulation which could directly kill cancer cells as well as activate the immunosuppressed tumor microenvironment to mount a robust antitumor immune response. Paclitaxel (PTX) and SP-LPS (nontoxic derivative of lipopolysaccharide) were selected as anticancer drug and immunostimulant respectively. Poly(lactic-co-glycolic acid) (PLGA) based PTX and SP-LPS containing nanoparticles (TLNP) were prepared by the double-emulsion method (w/o/w) and characterized in terms of size, zeta potential and transmission electron microscopy (TEM). The release behavior of PTX and SP-LPS from the TLNP exhibited a biphasic pattern characterized by an initial burst followed by slow continuous release. In vitro anticancer activity of TLNP was found to be higher compared to PTX when studied in a tumor cell-splenocyte coculture system. TLNP activated murine monocytes induced the secretion of various proinflammatory cytokines. After iv administration of TLNP in tumor bearing C57BL/6 mice, the amount of PTX in the tumor mass was found to be higher in TLNP treated mice as compared to commercial Taxol group at all time points studied. In vitro studies suggest that nanoparticles containing PTX and SP-LPS have both direct cytotoxicity and immunostimulatory activity. Hence this might have potential as a chemo-immunotherapeutic formulation against cancer with advantage over present day chemotherapy with Taxol, in terms of tumor targeting, less toxicity and immunostimulation. Keywords: Chemo-immunotherapy; nanoparticles; immunostimulation; PLGA; paclitaxel; SP- LPS; tumor targeting Introduction Paclitaxel (PTX) is a promising drug against a wide array of solid cancers, viz., breast cancer, lung cancer, ovarian cancer, head and neck cancer and acute leukemia. 1 It is known to promote tubulin polymerization to a hyperstabilized state, interfering with the normal dynamics necessary for cell division, leading to cell death. 2 The use of PTX is however limited by the drug’s toxicity and its poor aqueous solubility. 3 The current commercial formulation of PTX, i.e., Taxol, is a 1:1 (v/v) mixture of Chremophor EL and dehydrated alcohol. Some of the side effects are due to the Chremophor EL 4 while others are due to the limited availability in tumor mass and distribution to other tissues when administered via the iv route, reducing the effective dose of the drug. 5-7 Several attempts have been made to develop alternate * Corresponding authors. Mailing address: Product Development Cell-I, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India. Phone: 91-11-26703670. Fax: 91-11-26162125. E.mail: sangeeta@nii.res.in; pkumar@ nii.res.in. (1) Wani, M. C.; Taylor, H. L.; Wall, M. E.; Coggon, P.; McPhail, A. T. Plant antitumor agents VI. The isolation and structure of taxol: a novel anti leukemic and antitumour agent from Taxus brevifolia. J. Am. Chem. Soc. 1971, 93, 2325–2327. (2) Schiff, P. B.; Fant, J.; Horowitz, S. B. Promotion of microtubule assembly in vitro by taxol. Nature 1979, 227, 665–667. (3) Gelderblom, H.; Verweij, J.; Nooter, K.; Sparreboom, A.; Cre- mophor, E. L. the drawbacks and advantages of vehicle selection for drug formulation. Eur. J. Cancer 2001, 37, 1590–1598. (4) Tarr, B. D.; Yalkowsky, S. H. A new parenteral vehicle for the administration of some poorly soluble anti-cancer drugs. J. Parenter. Sci. Technol. 1987, 41, 31–33. (5) Sparreboom, A.; Tellingen, O. V.; Nooijen, W. J.; Beijnen, J. H. Tissue distribution, metabolism and excretion of paclitaxel in mice. Anticancer Drugs 1996, 7, 78–86. articles 1778 MOLECULAR PHARMACEUTICS VOL. 7, NO. 5, 1778–1788 10.1021/mp100153r  2010 American Chemical Society Published on Web 09/07/2010