Immunomedics Reports Preclinical Results On SN-38 ADCs - Quick Facts

(RTTNews) - Immunomedics, Inc. (IMMU) 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. The 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, the company said.

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, Immunomedics said.

Cynthia Sullivan, the company's President and CEO, said: "with regard to IMMU-132, which targets TROP-2 expressed on many epithelial cells, its active anticancer effect in patients with advanced triple-negative breast and small-cell lung cancers demonstrates broad activity in patients where irinotecan was not used."

The company also reported the development of a T-cell redirecting antibody for the potential treatment of pancreatic and gastric cancers. The company said this new cancer therapy involves making a bispecific antibody whereby one arm binds to the tumor and the other captures the patient's own T cells, retargeting them to attack and kill the tumor. Designated as (E1)-3s, the investigational agent is made up of an anti-CD3 antibody fragment linked securely using the company's patented DOCK-AND-LOCK protein conjugation technology to two TROP-2-targeting antibody fragments.