Mirvetuximab Soravtansine Improves Survival VS Chemo in FRα+ Ovarian Cancer

"Consistent with the strong topline MIRASOL data where superiority was seen across all efficacy endpoints, these subset analyses show that the improvements in [PFS, ORRs, and OS] demonstrated in the overall study population are also observed regardless of the number of prior lines of therapy," according to Toon Van Gorp, professor of Gynaecological Oncology at the University of Leuven.

Mirvetuximab soravtansine-gynx (Elahere) led to improvements in progression-free survival (PFS) and overall survival (OS) compared with chemotherapy in the treatment of patients with folate receptor α (FRα)–positive, platinum-resistant ovarian cancer, according to a press release on findings from a subset analysis of the phase 3 MIRASOL trial (NCT04209855).¹

Investigators presented these findings as part of an oral presentation at the 24th Congress of the European Society of Gynecological Oncology (ESGO) in Istanbul, Turkey.

With respect to PFS, treatment with mirvetuximab soravtansine reduced the hazard of disease progression or death in patients previously treated with PARP inhibitors (n = 251; HR, 0.58; 95% CI, 0.43-0.78; P = .0002) and those who were PARP inhibitor naïve (n = 191; HR, 0.74; 95% CI, 0.54-1.03; P = .0685).² Additionally, the experimental agent produced OS benefits in those who previously received PARP inhibitors (HR, 0.48; 95% CI, 0.33-0.71; P = .0002) and those who did not (HR, 0.90; 95% CI, 0.59-1.38; P = .6319).

Mirvetuximab soravtansine yielded PFS benefits among patients who received 1 or 2 prior lines of therapy (n = 245; HR, 0.61; 95% CI, 0.45-0.81; P = .0007), as well as those with 3 prior lines of treatment (n = 208; HR, 0.71; 95% CI, 0.52-0.98; P = .0362). The agent also reduced the hazard of progression or death with respect to OS in patients previously treated with 1 to 2 lines (HR, 0.66; 95% CI, 0.45-0.98; P = .0375) and those with 3 lines (HR, 0.65; 95% CI, 0.43-0.96; P = .0308).

The objective response rate (ORR) among patients receiving mirvetuximab soravtansine and chemotherapy, respectively, was 45% (95% CI, 36%-54%) vs 17% (95% CI, 11%-25%) in the prior PARP inhibitor subset (P <.0001) and 40% (95% CI, 30%-51%) vs 14% (95% CI, 8%-23%) in the PARP inhibitor-naïve population (P <.0001). Additionally, the ORR in each respective arm was 46% (95% CI, 37%-55%) vs 15% (95% CI, 9%-22%) in those receiving 1 or 2 prior lines of therapy (P <.0001) and 38% (95% CI, 29%-48%) vs 18% (95% CI, 11%-26%) in those receiving 3 (P = .0009).

Investigators reported that grade 3 or higher treatment-emergent adverse effects (TEAEs) affected 42% and 54% of patients receiving mirvetuximab soravtansine and chemotherapy, respectively. Additionally, 24% and 33% of patients in each respective arm experienced serious AEs, and 9% and 16% of patients discontinued study treatment due to TEAEs.

“Consistent with the strong topline MIRASOL data where superiority was seen across all efficacy endpoints, these subset analyses show that the improvements in [PFS, ORRs, and OS] demonstrated in the overall study population are also observed regardless of the number of prior lines of therapy,” Toon Van Gorp, professor of Gynaecological Oncology at the University of Leuven, said in the press release.¹

“These new data being presented at ESGO, including a consistent safety and tolerability profile, provide valuable insights for physicians into [mirvetuximab soravtansine’s] broad and meaningful benefit compared to chemotherapy and further position [mirvetuximab soravtansine] to become the new standard of care for patients with FRα-positive, [platinum-resistant ovarian cancer].”

In the open-label MIRASOL trial, 453 patients with platinum-resistant ovarian cancer expressing high levels of FRα were randomly assigned 1:1 to receive 6 mg/kg adjusted ideal body weight of mirvetuximab soravtansine every 3 weeks or investigator’s choice of paclitaxel, pegylated liposomal doxorubicin, or topotecan. The trial’s primary end point was PFS per investigator assessment. Secondary end points included ORR, OS, and patient-reported outcomes.

The FDA approved mirvetuximab soravtansine in FRα–positive, platinum-resistant ovarian, fallopian tube, or primary peritoneal cancer previously treated with 1 to 3 lines of therapy in November 2022.³ The regulatory agency granted accelerated approval based on data from the phase 3 SORAYA trial (NCT04296890).

References

1. ELAHERE® shows overall and progression-free survival benefit regardless of prior PARPi exposure or prior lines of therapy in FRα-positive platinum-resistant ovarian cancer. News release. ImmunoGen Inc. September 28, 2023. Accessed October 2, 2023. https://bit.ly/3LJB79q
2. Gorp VT, Sabatier R, Konecny GE, et al. Efficacy of mirvetuximab soravtansine in folate receptor alpha high, platinum-resistant ovarian cancer by type and number of prior treatment regimens: an exploratory analysis. Presented at: 24th European Congress on Gynaecological Oncology; September 28 – October 1, 2023; Istanbul, Turkey. Abstract 1015 and 1056.
3. ImmunoGen announces FDA accelerated approval of ELAHERE™ (mirvetuximab soravtansine-gynx) for the treatment of platinum-resistant ovarian cancer. News release. ImmunoGen. November 14, 2022. Accessed October 2, 2023. https://bwnews.pr/3AayMyH