Immunomedics ADC Gets Orphan Status

Immunomedics‘ IMMU-132, an antibody-drug conjugate for solid cancer therapy, has received Orphan Drug status from the Office of Orphan Products Development of the FDA for the treatment of small cell lung cancer (SCLC).

In an early Phase I clinical study, IMMU-132 has produced partial responses in patients with small cell lung cancer, colorectal cancer, and triple negative breast cancer. IMMU-132 is currently in Phase II clinical development focusing on a few select types of solid cancers.

IMMU-132 is an active antibody-drug conjugate containing the humanized anti-TROP-2 antibody, hRS7, conjugated by a pH sensitive linker to SN-38. TROP-2 is expressed by many human tumors, such as cancers of the breast, cervix, colon and rectum, kidney, liver, lung, ovary, pancreas, and prostate, but with only limited expression in normal human tissues. hRS7 internalizes into cancer cells following binding to TROP-2, making it a suitable candidate for the delivery of cytotoxic drugs.

SN-38 is the active metabolite of irinotecan, which is a standard therapy for patients with metastatic colorectal cancer, but has major gastrointestinal and hematologic toxicity. By attaching SN-38 to tumor-targeting antibodies, delivery of SN-38 to the tumor may be increased several-fold while mitigating systemic toxicity.