Mirvetuximab soravtansine is the first folate receptor alpha (FRα)-targeting antibody-drug conjugate (ADC). It uses a humanised FRα-binding antibody to target the ADC specifically to FRα-expressing cancer cells and potent anti-tumour agent DM4 to kill the targeted cancer cells.

The Phase III study was conducted in North America and Europe and assessed mirvetuximab soravtansine compared to chemotherapy in women with folate receptor alpha (FRα)-positive, platinum-resistant ovarian cancer.

A total of 366 patients were randomised in a 2:1 ratio to receive either investigational drug mirvetuximab soravtansine or the physician’s selection of single-agent chemotherapy (pegylated liposomal doxorubicin, topotecan, or weekly paclitaxel).

Patients eligible to receive the treatment were diagnosed with platinum-resistant ovarian cancer that expresses medium or high levels of folate receptor alpha (FRα) and were treated with up to three prior regimens.

Even though the trial did not meet PFS, the results demonstrated promising efficacy results in folate receptor alpha (FRα) high patients, favourable tolerability, and a differentiated safety profile compared to chemotherapy.

The study also showed that mirvetuximab soravtansine was well-tolerated, with fewer patients experiencing grade III or greater treatment emergent adverse events. The trial also recorded fewer dose reductions and a reduction in discontinuations due to drug-related TEAEs compared with chemotherapy.

ImmunoGen said the registration study for Mirvetuximab in ovarian cancer is on track to start by the end of this year.

At ESMO 2019, ImmunoGen also presented initial data from the Phase Ib Forward II triplet cohort assessing mirvetuximab soravtansine in combination with Carboplatin and Avastin.

The company said the combination demonstrated encouraging anti-tumour activity and preliminary findings support ongoing study in platinum-sensitive patients.