Benzinga | Sep 18, 2020 08:02AM EDT

Immunomedics Reports Trodelvy Delivered Improvements In Inhibitory Concentration Of SN-38 For BMBC, rGBM In Brain Cancer Patients

Immunomedics, Inc. (NASDAQ:IMMU) ("Immunomedics" or the "Company"), a leading biopharmaceutical company in the area of antibody-drug conjugates, today announced that Trodelvy delivered 150-fold and 40-fold the 50% inhibitory concentration (IC50) of SN-38 for BMBC and rGBM, respectively, and produced partial responses in both cohorts of brain cancer patients.

"These early intracranial responses are very encouraging signs of sacituzumab govitecan's activity in central nervous system (CNS) tumors as previously observed in preclinical models,"1 said Andrew J. Brenner, M.D. Ph.D., Clinical Investigator, Institute for Drug Development; Co-Leader, Experimental and Developmental Therapeutics Program; S & B Kolitz/CTRC-Zachry Endowed Chair in Neuro-Oncology Research, Mays Cancer Center at UT Health San Antonio, San Antonio, TX, who reported the results in a mini oral session on CNS tumors at the ESMO Virtual Congress 2020. "With a hydrolysable linker that allows SN-38 to be released at the tumor site and given that SN-38 freely crosses the blood brain barrier and is active in the nanomolar range for most cancer cells, including triple-negative breast cancer (TNBC) and GBM, sacituzumab govitecan has the prerequisite ability to deliver therapeutically relevant concentrations of SN-38 across an undisrupted vasculature. The early clinical results in patients with neoplastic involvement of the brain warrant further development of Trodelvy in these aggressive and lethal cancers."

At the time of data cutoff, 19 patients (7 BMBC and 12 rGBM) were enrolled into the study. Key clinical data from evaluable patients are summarized below. No new safety signals were observed.

BMBC rGBMTumor response*, N 7 7Partial response, n 2 2Ongoing progression-free survival, n (range) 4 (161-279 6 (7-315 days) days)Residual measurable disease, n 4 7Tumor SN-38 concentrations, N 4 6Mean total SN-38 (nM) (range) 455 (174-1,160) 270 (93-687)Mean free SN-38 (nM) (range) 73 (15-198) 46 (20-90)SN-38G# detected in 1 patient in each cohort 3.4 5.8(nM)* Per RANO criteria, # SN-38 glucuronide, an inactive metabolite of SN-38

"Brain metastasis is a significant concern in patients with TNBC, and we are very encouraged by these early-stage study results," stated Dr. Loretta M. Itri, Chief Medical Officer of Immunomedics. "Additionally, given that GBM is a disease with great unmet need, we are working in close collaboration with Dr. Brenner and others, including the Southwestern Oncology Group, to design programs that could potentially elucidate the role of Trodelvy in the management of BMBC and rGBM."

Patients with BMBC or rGBM were enrolled into the single center study (NCT03995706) to receive a single intravenous dose of Trodelvy at 10 mg/kg one day before surgical resection. Tumor and corresponding serum were collected during surgery to measure their levels of SN-38 and its metabolites. Following recovery, patients resumed Trodelvy treatment at 10 mg/kg on days 1 and 8 of 21-day cycles and were assessed for responses by MRI every third cycle using response assessment in neuro-oncology (RANO) criteria.