-- Preclinical Studies Presented at 2014 Annual Meeting of the American Association for Cancer Research (AACR) --
-- Novel T-cell Redirecting Immunotherapeutic Agent Also Presented --
SAN DIEGO, April 8, 2014 (GLOBE NEWSWIRE) -- Immunomedics, Inc. (Nasdaq:IMMU), a biopharmaceutical company primarily focused on the development of monoclonal antibody-based products for the targeted treatment of cancer, autoimmune and other serious diseases, today reported results from preclinical studies on the Company's two investigational SN-38-containing antibody drug conjugates (ADCs), IMMU-130 and IMMU-132, that demonstrated a high therapeutic index for both agents.IMMU-130 consists of SN-38 linked to the Company's proprietary anti-CEACAM5 humanized monoclonal antibody. It is currently in a Phase II trial for the treatment of patients with metastatic colorectal cancer. IMMU-132 has SN-38 conjugated to another proprietary anti-TROP-2 humanized monoclonal antibody, which is being evaluated as a therapy for a variety of epithelial cancers, including triple-negative breast cancer and small-cell lung cancer. These two ADCs were developed to facilitate SN-38-targeted delivery to tumor cells, improve its efficacy, decrease the toxicity of SN-38, and improve its bioavailability, which is hampered by a low rate of conversion from irinotecan, the parent drug of SN-38. At doses below the maximum tolerated dose in mice, both IMMU-130 and IMMU-132 were effective in a number of animal models of diverse human solid cancers. Smaller fractionated doses, administered over an extended period, controlled tumor growth better than higher doses administered less frequently, which is consistent with the clinical observations. In addition, following IMMU-132 administration, nearly all of the SN-38 remained conjugated to the antibody. However, when the ADC binds to the antigen on the tumor cells and is internalized, SN-38 is released, causing tumor cell death. These ADCs deliver 120-times more SN-38 to tumors than when the maximum dose of irinotecan is administered. Therefore, the ADC maintains SN-38 in a highly potent form, releasing it in the tumor to exert its maximum therapeutic anti-cancer effects. This may explain why in the ongoing clinical studies these ADCs appear to produce manageable and less toxicity than irinotecan at its therapeutic doses. For example, these ADCs, at therapeutic doses, do not cause the severe diarrhea associated with irinotecan treatment, and this may be related to the observation that fecal SN-38 is much higher in animals treated with irinotecan, compared to IMMU-132 treatment.