Genetically Engineered HSV-1 Phase 1 Study for the Treatment of Recurrent Malignant Glioma

M032 is a second-generation oncolytic herpes simplex virus (oHSV) that is conditionally replication competent; that is, similar to G207, a first generation oHSV, it can replicate in tumor cells, but not in normal cells, thus killing the tumor cells directly through this process. Replication of M032 in the tumor itself not only kills the infected tumor cells, but causes the tumor cell to act as a factory to produce new virus. These virus particles are released as the tumor cell dies, and can then proceed to infect other tumor cells in the vicinity, and continue the process of tumor kill. In addition to this direct oncolytic activity, the virus carries a therapeutic payload--acting as a gene therapy vector, too--and causes the tumor cell to synthesize and secrete an immunity-stimulating protein called Interleukin-12 (IL-12) before it is killed. This IL-12 is released and promotes an immune response against surviving tumor cells, which increases the antitumor effect of the therapy. The IL-12 that is expressed can also produce an anti-angiogenic effect, by interfering with the production of new tumor blood vessels necessary to allow tumor growth. Anti-angiogenic therapies potentially starve the tumor of necessary oxygen and nutrients. Thus, the M032 oHSV produces three different potential mechanisms for antitumor effects. The virus has also been genetically-engineered to minimize the production of any toxic effects for the patient receiving the therapy.