-- Cancer Types Include Colorectal, Esophageal, Triple-Negative Breast, Small-Cell and Non-Small-Cell Lung –
-- Preclinical Study on IMMU-132 Also Presented --
"We believe this is the first ADC for solid cancers that is active in so many cancer types, consistent with the broad increased expression of the target antigen, TROP-2, in most epithelial cancers," commented
IMMU-132 is made up of SN-38, the active metabolite of irinotecan, conjugated to the Company's humanized anti-TROP-2 antibody. In patients who relapsed or were refractive to prior topoisomerase I or II inhibitors, this ADC demonstrated subsequent activity, suggesting that it can overcome resistance to such inhibitors, including irinotecan.
Even after failing multiple prior therapies, a median time to progression of at least 12.6 weeks (range 6.0-51.4 weeks) was observed in 48 patients with at least 1 CT assessment. One patient with hormone-refractive prostate cancer has a long-term, durable stable disease response, which is approaching a year. This patient has received 30 doses of IMMU-132 and treatment is continuing. Despite repeated dosing, no antibodies against the ADC, neither to the antibody nor to SN-38, have been detected in this or any other patients.
A total of 69 patients with a median of 3 prior therapies have been enrolled into the multicenter trial, including 13 patients with pancreatic cancer. Results from the pancreatic cancer patients have recently been presented and were not included in this report. Please refer to the Company's press release at http://www.immunomedics.com/pdfs/news/2014/pr05202014.pdf for more information on the results in pancreatic cancer. Also excluded were 8 patients who had clinical progression and withdrew before CT assessment.
The Phase I/II results were presented by
In animals given the ADC, nearly all of the SN-38 was found to remain bound to the antibody during blood circulation. As such, IMMU-132 is not toxic to the animal but maintains SN-38 in a latent, toxic form to be released upon binding to the TROP-2 antigen on the tumor cells and internalized. In contrast, when irinotecan is converted to SN-38, a significant amount of the metabolite is detoxified. As a result, IMMU-132 delivered 120-times higher amounts of SN-38 to the tumors compared to irinotecan at its maximum tolerated dose. This corroborates the higher therapeutic index believed to be achieved with IMMU-132 in the clinical studies.
In a variety of human cancers grafted to mice, the ADC produced a broad spectrum of tumor-growth-inhibition activities, even at doses well below the maximum tolerated doses in the animal. More importantly, long-term dosing using smaller, fractionated doses was found to be more effective than larger, less frequent dosing. This is consistent with the clinical experience where IMMU-132 is administered on days 1 and 8 of a 21-day cycle, with cycles repeated for as long as possible. Some patients in the IMMU-132 Phase I/II trial have been under therapy for up to 11 months.
"These preclinical studies have provided us with important information on the properties of this promising investigational therapeutic, which we believe has the potential to be a novel platform for the therapy of diverse metastatic solid cancers," stated Ms. Sullivan.
This release, in addition to historical information, may contain forward-looking statements made pursuant to the Private Securities Litigation Reform Act of 1995. Such statements, including statements regarding clinical trials (including the funding therefor, outcomes, timing or associated costs), out-licensing arrangements (including the timing and amount of contingent payments), forecasts of future operating results, potential collaborations, and capital raising activities, involve significant risks and uncertainties and actual results could differ materially from those expressed or implied herein. Factors that could cause such differences include, but are not limited to, new product development (including clinical trials outcome and regulatory requirements/actions), our dependence on UCB for the further development of epratuzumab for non-cancer indications, risks associated with the outcome of pending litigation, competitive risks to marketed products and availability of required financing and other sources of funds on acceptable terms, if at all, as well as the risks discussed in the Company's filings with the
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