US-based biopharmaceutical firm Immunomedics (IMMU) has received orphan drug status from the Office of Orphan Products Development of the US Food and Drug Administration (FDA) for its antibody-drug conjugate for solid cancer therapy IMMU-132 for the treatment of small cell lung cancer (SCLC).
IMMU-132 has reportedly produced partial responses in patients with small cell lung cancer, colorectal cancer and triple negative breast cancer in an early Phase I clinical study.
Immunomedics president and chief executive officer Cynthia Sullivan said: "In addition to small cell lung cancer, the agent is currently in Phase II clinical development focusing on a few select types of solid cancers."
IMMU-132 contains the humanised anti-TROP-2 antibody, hRS7, conjugated by a pH sensitive linker to SN-38.
TROP-2 is expressed by many human tumours, including cancers of the breast, cervix, colon and rectum, kidney, liver, lung, ovary, pancreas, and prostate, but with only limited expression in normal human tissues, while hRS7 internalises into cancer cells following binding to TROP-2, making it a suitable candidate for the delivery of cytotoxic drugs.
SN-38 is an active metabolite of irinotecan, which is a standard therapy for patients with metastatic colorectal cancer, but has major gastrointestinal and hematologic toxicity.
According to the company, by attaching SN-38 to tumour-targeting antibodies, delivery of SN-38 to the tumour is expected to be increased several-fold while mitigating systemic toxicity.
The orphan drug status qualifies the company for several development incentives, including tax credits for qualified clinical testing, a waiver from the FDA’s application User Fee for marketing application, and a seven-year period of marketing exclusivity in the US for IMMU-132, if it is approved by the FDA for the treatment of patients with SCLC.
Image: Histopathologic image of small cell carcinoma of the lung. Photo: courtesy of KGH.