The present invention relates to modulation of the tumor microenvironment to increase cancer specific immune responses. Conjugates, nanoparticles and formulations of the present invention relieve the inhibitory effect induced by tumor cells, and enhance antitumor immunity. The compostions provided herein can be used as immunotherapies, or as adjuvants used in conjunction with other immunotherapies such as peptide vaccines, cell vaccines and/or adoptive T cell transfer.
