Why ImmunoGen Stock Hangs Today – The Fool Motley

What happened

Actions of ImmunoGen (NASDAQ: IMGN) are collapsing today, down 45.9% at 11:31 am EST, after biotechnology announced disappointing news from its Phase 3 clinical trial of Forward I evaluating mirvetuximab soravtansine in treatment ovarian cancer.

ImmunoGen indicated that mirvetuximab soravtansine did not achieve the primary endpoint of progression-free survival (PFS) in the study, either in the entire enrolled group of patients or in the subgroup of patients with elevated folate alpha receptor. The clinical study included patients with platinum-resistant ovarian cancer expressing medium or high levels of folate alpha receptor that had been treated with up to three previous treatments. .

So what

Investors had been very worried about the results of the Forward I study. The ImmunoGen stock price fell more than 20% on Wednesday as some investors were preparing for bad news. But how bad were the news? Pretty bad – but there was at least a glimmer of hope.

The expanded group of study patients who received mirvetuximab soravtansine did not show any significant difference in terms of progression-free survival or overall survival compared with patients receiving only chemotherapy. However, progression-free survival and overall survival time were longer in the subgroup of patients with high folate receptor alpha expression taking ImmunoGen drug than in the group of chemotherapy patients. A higher confirmed overall response rate was also observed in the subgroup of patients treated with mirvetuximab soravtansine.

However, the problem was that for the results in the subgroup of patients with high folate receptor alpha expression to be statistically significant, the p-value (a measure of the calculated probability that a hypothesis is true) be less than or equal to 0.025 if the p-value of the entire study was greater than 0.05.

All of these statistics may seem a little confusing, but in summary, the fact that mirvetuximab soravtansine was not clearly better than chemotherapy in the larger group of patients meant that the obstacle was higher for the drug in the treatment of subgroup of smaller patients. And this obstacle has not been crossed.

Now what

ImmunoGen Medical Director, Anna Berkenblit, said the company was performing additional analyzes based on some of the positive efficacy signals observed in the Forward study. CEO Mark Enyedy added that ImmunoGen "will deepen the assessment of Forward I data to determine potential next steps with a monotherapy approach."

However, the best hope for treatment with mirvetuximab soravtansine will now be part of a multi-drug regimen. Enyedy noted that ImmunoGen had generated encouraging data in combination treatment studies.

Biotechnology has three other antibody-drug conjugates in development. ImmunoGen also has approximately $ 295 million in cash to fund its operations and advance its candidates. But the future of society seems much darker with the latest clinical setback.