- Objective response rate (ORR) of 53% - as single agent - in patients with folate-receptor alpha (FRα)-positive platinum-resistant ovarian cancer. Majority of responses are ongoing. Clinical development program advancing, expanding.
The findings reported today are from an ongoing Phase 1 trial. Once the recommended Phase 2 dose (RP2D) of mirvetuximab soravtansine was established during dose finding (abstract #5558), an expansion cohort was opened to assess the safety and activity of this ADC specifically in the treatment of patients with FRα-positive platinum-resistant ovarian cancer. Approximately 80% of the patients screened have met the criteria for having FRα-positive disease.
Twenty-two patients were included in the analysis reported today - two from the dose-escalation phase of the trial and the twenty enrolled in the expansion cohort at the time of data cutoff for presentation (4/30/15). All had FRα-positive platinum-resistant ovarian cancer and had received mirvetuximab soravtansine at the RP2D (6.0 mg/kg, given every three weeks). All had previously received taxane as well as platinum therapy. Thirteen were still on study at the time of data cutoff.
The majority of adverse events reported were low grade (grade 1 or 2), with diarrhea, blurred vision, nausea, vomiting, fatigue, and abdominal pain the most common treatment-emergent events reported ( > 20% of patients).
Seventeen of the 22 patients were included in the efficacy analysis; the other five patients were still on study and had not yet reached their first assessment.
- Nine of these 17 patients had an objective response (8 partial responses, 1 complete response) to treatment, for an ORR of 53%.
- The responses in six of these nine patients were ongoing at the time of data cutoff, with five of these six patients on treatment for more than 15 weeks.
"These initial clinical findings with mirvetuximab soravtansine in the treatment of patients with FRα-positive platinum-resistant ovarian cancer are highly encouraging," commented Dr.
"Based on these findings, we are implementing a development plan designed to advance mirvetuximab soravtansine as quickly as possible while also recognizing the potential to benefit the greatest number of patients," commented Dr.
About Platinum-Resistant Ovarian Cancer
Each year, there are approximately 21,300 new cases of ovarian cancer diagnosed in the US and more than 14,200 women die from the disease.1 ImmunoGen estimates that approximately 2,000-3,000 of these women have FRα-positive, platinum-resistant ovarian cancer previously treated with at least three prior lines of therapy.
Standard first-line therapy for ovarian cancer is a platinum-based regimen (e.g., carboplatin plus a taxane and potentially additional agents). Once the cancer becomes platinum-resistant, patients may receive single-agent therapy. Response rates with these agents in the second-/third-line setting are typically around 15-20%.2
About the Study Reported
The findings reported today are from a Phase 1 trial assessing mirvetuximab soravtansine for the treatment of FRα-positive solid tumors. After the RP2D was established in patients likely to have FRα-positive disease using a once every 3-week dosing schedule, an expansion cohort was opened to evaluate the ADC specifically in patients with FRα-positive platinum-resistant ovarian cancer when administered as a single agent at this RP2D.
To be eligible for enrollment in this expansion cohort, patients must have ovarian cancer that responded to primary platinum therapy, but then progressed within six months or progressed on or within six months of treatment with subsequent platinum therapy. The cancer also must be FRα-positive, assessed by immunohistochemistry. Approximately 80% of patients screened met this criteria based on the
This expansion cohort has been expanded from 20 to 40 patients to obtain additional experience in this patient population.
About Mirvetuximab Soravtansine
Mirvetuximab soravtansine (IMGN853) is a FRα-targeting ADC developed and wholly owned by ImmunoGen. It is the first and only ADC to this target to enter clinical testing, and comprises a FRα-binding antibody conjugated to DM4, a potent cancer-cell killing agent developed by ImmunoGen specifically for use in ADCs. The antibody serves to target the DM4 specifically to FRα-positive cancer cells which the DM4 can then kill.
FRα is highly expressed on many cases of epithelial ovarian cancer, and on other types of solid tumors including endometrial cancer and some non-small cell lung cancers. Mirvetuximab soravtansine is currently being assessed for the treatment of FRα-positive, platinum-resistant ovarian cancer and for FRα-positive relapsed/refractory endometrial cancer, with additional assessments anticipated.
About
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2From prescribing information and published clinical data.
This press release includes forward-looking statements. For these statements, ImmunoGen claims the protection of the safe harbor for forward-looking statements provided by the Private Securities Litigation Reform Act of 1995. It should be noted that there are risks and uncertainties related to the development of novel anticancer products, including mirvetuximab soravtansine (IMGN853), including risks related to clinical studies and regulatory processes, their timings and results. A review of these risks can be found in ImmunoGen's Annual Report on Form 10-K for the fiscal year ended
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