ImmunoGen has announced positive results from the Phase III MIRASOL trial of Elahere (mirvetuximab soravtansine-gynx) for platinum-resistant ovarian cancer patients with medium to high levels of folate receptor alpha.
Elahere has met the primary endpoint of progression-free survival (PFS) and demonstrated statistically significant improvements in the objective response rate and overall survival (OS). Such groundbreaking results render Elahere the first to demonstrate an overall survival advantage for patients with platinum-resistant ovarian cancer.
Elahere is an antibody-drug conjugate (ADC) consisting of a monoclonal antibody against FRα linked to the maytansinoid payload DM4. FRα is expressed in approximately 35-40% of ovarian cancer patients, offering Elahere a competitive advantage as it has the potential to minimise off-target effects and reduce toxicity compared to traditional chemotherapy.
The ADC, currently being developed by ImmunoGen, was granted accelerated FDA approval in November 2022, making it the first approved therapy for platinum-resistant ovarian cancer since 2014. Ovarian cancer patients diagnosed with late-stage cancer usually undergo surgery, followed by platinum-based chemotherapy and maintenance therapy. However, in approximately 70-80% of cases, patients develop resistance to the treatment.
MIRASOL enrolled 453 ovarian cancer patients who had undergone one to three prior lines of therapy, who were positive for FRα, and who showed resistance to platinum chemotherapy. Elahere demonstrated a significant and clinically meaningful 35% reduction in the risk of disease progression or death, compared to standard chemotherapy.
Patients treated with Elahere had a median PFS of 5.6 months, which was slightly longer than the 4 months observed in patients who received standard chemotherapy. Moreover, patients in the Elahere arm showed a median overall survival of 16.5 months while those in the investigator’s choice chemotherapy paclitaxel arm had a median OS of 12.8 months (hazard ratio 0.67).
According to GlobalData’s consensus analyst forecasts, Elahere’s sales in this indication in the US are expected to reach $450m by 2029. However, its market potential is currently confined to later-stage treatment in platinum-resistant ovarian cancer. Despite this, the results from the MIRASOL trial provide ImmunoGen with the foundation for pursuing the use of Elahere in combination with Avastin for platinum-resistant ovarian cancer.
If approved this year, Elahere could gain market share from the number of patients treated with Avastin combinations, which GlobalData expects to be around 9,800 patients in the US in all lines of treatment. Based on the MIRASOL results, ImmunoGen intends to request marketing authorisation from the European regulatory authorities in the latter half of 2023.