May 17 (Reuters) - Latest results from a mid-stage trial of ImmunoGen Inc's experimental antibody-drug conjugate show that it shrinks or stabilizes tumors in nearly half of advanced ovarian cancer patients with at least medium levels of a key biomarker whose disease has become resistant to standard chemotherapy.
Looking at all 113 patients so far evaluated in the trial, 30 percent responded to the drug and patients lived for a median of 4.3 months without their disease progressing.
For its pivotal trial, ImmunoGen is enrolling only patients with platinum-resistant disease and medium or high levels of a biomarker known as folate receptor alpha who have received up to three prior lines of therapy. Of the 36 trial earlier-stage trial patients meeting those criteria, 47 percent responded to the drug and median progression-free survival was 6.7 months, the company said on Wednesday. The full research will be presented next month at a meeting of the American Society of Clinical Oncology.
"We are looking to get on the market as quickly as possible in the single agent setting," ImmunoGen Chief Executive Mark Enyedy told Reuters. The company expects to have final data from the pivotal trial in 2019.
About 22,400 American women are diagnosed with ovarian cancer each year and about 14,000 will die from the disease, according to the American Cancer Society.
Mirvetuximab soravtansine combines an antibody targeting a receptor, anti-folate alpha, associated with certain types of cancer cells with an anti-tumor agent to kill the targeted cells.
ImmunoGen is also studying the drug in combination with other treatments for earlier-stage ovarian cancer, and said it will move forward with more advanced combination trials involving Roche Holding AG's Avastin and Merck & Co Inc's Keytruda. It is also evaluating future studies with carboplatin chemotherapy combinations.
Early-stage trial results showed that for advanced ovarian cancer patients treated with Avastin and the ImmunoGen antibody-drug conjugate, 29 percent responded to the treatment with a median progression-free survival of 9.5 months.
Side effects in the Avastin group included excess protein in the urine for 36 percent of patients and hypertension in 21 percent of patients.
ImmunoGen said it was too early to assess results for the Keytruda arm of the trial. (Reporting By Deena Beasley; Editing by Bill Rigby)