Mirvetuximab Soravtansine Real-World Ovarian Cancer Data Matches MIRASOL

Recent real-world data confirms that Elahere (mirvetuximab soravtansine-gynx) survival outcomes for recurrent ovarian cancer align with pivotal MIRASOL trial (NCT04209855) findings. While effective, a retrospective analysis presented at SGO 2026 highlights significant toxicity risks and lower life expectancy for patients with poor performance status (ECOG PS).

The analysis focused on 66 patients receiving mirvetuximab soravtansine at a tertiary academic National Cancer Institute–designated cancer center and an associated private hospital between November 2022 and April 2025. In these patients, the median overall survival (OS) was 16.4 months, and the median progression-free survival (PFS) was 5.3 months. Seventy percent of patients experienced disease progression, 14% achieved a partial response, 9% had stable disease, and 2% achieved a complete response.

Furthermore, the median OS was meaningfully longer in patients with an ECOG PS of 0 or 1 (n = 57) compared with patients with a PS greater than 1 (n = 9), at 20.3 months (95% CI, 13.4-not evaluable [NE]) and 6.0 months (95% CI, 0.3-NE), respectively (log-rank P = .0006). Toxicity was also common across the cohort, with 91% of patients experiencing any-grade adverse effects, including ocular toxicity (53%), neurologic toxicity (50%), hematologic toxicity (42%), and gastrointestinal toxicity (33%).

"PS should be considered before initiating [mirvetuximab soravtansine], as patients with poorer PS should be counseled to expect substantially shorter life expectancy than reported in trials," lead study author Anna V. Jones, MD, and colleagues at the Washington University School of Medicine in St. Louis, Missouri, stated in a poster presentation of the data. “[Mirvetuximab soravtansine–associated] toxicity is [also] common, and providers should be versed in their counseling and management.”

What is the context for this analysis?

On March 22, 2024, the FDA granted full approval to mirvetuximab soravtansine for adult patients with folate receptor alpha (FRα)–positive, platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer who received 1 to 3 prior systemic therapies.²

The approval was supported by data from the phase 3 MIRASOL trial (NCT04209855), in which mirvetuximab soravtansine demonstrated a statistically significant improvement in OS, PFS, and overall response rate (ORR) over investigator's choice of chemotherapy in 453 patients with platinum-resistant, FRα-high disease. The median OS was 16.5 months (95% CI, 14.5–24.6) vs 12.7 months (95% CI, 10.9-14.4) in these respective groups (HR, 0.67; 95% CI, 0.50-0.88; P = .0046). The median PFS values were 5.6 months (95% CI, 4.3-5.9) with mirvetuximab soravtansine vs 4.0 months (95% CI, 2.9-4.5) with chemotherapy (HR, 0.65; 95% CI, 0.52-0.81; P < .0001). Respective ORRs were 42% (95% CI, 36%-49%) and 16% (95% CI, 12%-22%; P < .0001).

Of note, MIRASOL enrolled a carefully selected population limited to patients with 1 to 3 prior chemotherapy regimens, high FRα expression on an FDA-approved test, platinum-resistant disease, and an ECOG PS of 0 or 1.¹ However, the patient population receiving mirvetuximab soravtansine in routine clinical practice extends well beyond these eligibility criteria, and outcomes in this broader group are poorly characterized. The current analysis was designed to address this knowledge gap.

How was this study designed, and what were the baseline characteristics of patients on the study?

In this retrospective study, data on patient demographics, disease characteristics, and toxicities were obtained from electronic medical records. OS and PFS were estimated via the Kaplan-Meier method, and a multivariable Cox hazard regression model was applied to assess associations between patient demographic and treatment characteristics and survival in the cohort following treatment with mirvetuximab soravtansine.

Baseline characteristics were as follows:

• Median age at first dose of mirvetuximab soravtansine: 65 years (IQR, 57.0-74.0).
• Number of prior treatment regimens: 37.9% received 5 or more prior treatment regimens, 19.7% received 4, 19.7% received 3, 15.2% received 2, and 7.6% received 1 prior regimen.
• Platinum status: 51.5% of patients were platinum-resistant, 22.7% were platinum-refractory, and 25.8% were platinum-sensitive.
• FRα expression on first biopsy: Positive in 77.3% of patients, low in 9.1%, medium in 6.1%, negative in 4.5%, and unknown in 3.0% of patients.
• BMI: 33.3% of patients were normal weight, 27.3% were overweight, 21.2% were class 1 obese, 7.6% were class 3 obese, 6.1% were underweight, and 4.5% were class 2 obese.

Were differences in OS/PFS observed according to platinum status or other patient factors?

Survival outcomes did not differ significantly across the platinum-refractory (n = 15), platinum-resistant (n = 34), and platinum-sensitive (n = 17) subgroups (log-rank P = .68), and OS also did not reach statistical significance across these groups (log-rank P = .68). The median PFS in these respective groups was 4.8 months (95% CI, 2.0-8.0), 5.2 months (95% CI, 3.1-7.1), and 6.4 months (95% CI, 3.5-16.9). Corresponding median OS values were 15.8 months (95% CI, 5.9-NE), 16.4 months (95% CI, 7.0-NE), and 20.3 months (95% CI, 15.4-NE).

Taxane resistance was also not found to be associated with impaired survival (P = .64), and patients with more than 3 prior regimens did not have increased mortality compared with those who had received fewer regimens (P = .41). Furthermore, obesity was not associated with a significantly different hazard of death (HR, 0.66; 95% CI, 0.24-1.82; P = .42) or disease progression (HR, 0.65; 95% CI, 0.33-1.25; P = .19) relative to non-obese patients.

What did repeat folate receptor testing reveal?

An exploratory observation regarding serial FRα assessment was reported in a subset of patients who underwent a second biopsy (n = 7). Of those, 5 patients had an increase in folate receptor positivity on repeat biopsy, 1 had a decrease in folate receptor expression, and 1 had negative expression. Study investigators highlighted this dynamic nature of FRα expression across lines of therapy as an area warranting further prospective investigation.

“Future investigations should explore mechanisms of resistance to prespecify patients who will not respond despite FRa expression, and future studies are warranted to evaluate factors that could alter folate receptor expression on repeat biopsy,” they concluded.

References

• Jones AV, Furuya RL, Massad LS, et al. Real-world outcomes after mirvetuximab soravtansine treatment for recurrent ovarian cancer. Presented at: 2026 SGO Annual Meeting on Women's Cancer; April 10–13, 2026; San Juan, PR. Poster 1261.
• FDA approves mirvetuximab soravtansine-gynx for FRα positive, platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer. FDA. March 22, 2024. Accessed April 11, 2026. https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-mirvetuximab-soravtansine-gynx-fra-positive-platinum-resistant-epithelial-ovarian