Immunomedics, Inc. (IMMU) revealed on Tuesday at the Clinical Science Symposium on Raising the Bar for Targeted Therapies for Lung Cancers of the American Society of Clinical Oncology’s (ASCO) 2016 Annual Meeting that its investigational antibody-drug conjugate (ADC), sacituzumab govitecan (IMMU-132), shrank tumors by at least 30% among 12 out of 46 evaluable metastatic non-small-cell lung cancer (NSCLC) patients who had received a median of three prior therapies.

The interim results showed that the median progression-free survival (PFS) is at about four months while the overall survival (OS) is at 10.5 months. The findings among the two major NSCLC subtypes, adenocarcinoma and squamous cell carcinomas, are particularly compelling with massive tumor shrinkage and disease stabilization.

The subjects were administered with the recommended sacituzumab govitecan dose of 10 mg/kg on days 1 and 8 of a 21-day experiment cycle.

Efficacy and Safety Results

Given that the subjects are the recipients of heavy pretreatment, the safety data of IMMU-132 are “striking”— as Dr. Ross Camidge, M.D., Ph.D., results presenter, noted. Dr. Camidge added that the overall objective response rate (ORR) of 13% is pretty impressive.

Moreover, he said that eight out of the 12 patients who had received anti-PD-1/PD-L1 treatments previously demonstrated partial response or stabilized disease. On that note, Dr. Camidge said that this indicates further possibilities for sacituzumab govitecan in routine immunotherapy.

About Sacituzumab Govitecan

The ADC primarily contains the active irinotecan metabolite, SN-38. It is an approved chemotherapeutic drug for cancer patients. Basically, SN-38 cannot be administered directly due to high levels of toxicity. As a result, Immunomedics developed sacituzumab govitecan as it explores more treatment options specifically for SCLC patients.

Previously, the drug has already showcased impressive treatment capabilities for triple-negative breast cancer (TNBC) patients, for which the US Food and Drug Administration (FDA) has granted sacituzumab govitecan a Breakthrough Therapy designation.

Stock Decline

Amid these latest encouraging study results, the company’s stock plummeted on Friday after it was kicked out of ASCO’s annual conference due to an alleged confidentiality violation. Accordingly, Immunomedics already presented its scheduled presentation for the conference in a separate meeting last April.