Adverse events (AEs) were any noxious, pathologic, or unintended change in anatomical, physiologic, or metabolic function that developed or worsened during the clinical study, not necessarily having a causal relationship to study drug. Severity was graded according to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) v4.03: Grade 1=mild, Grade 2=moderate, Grade 3=severe, Grade 4=life-threatening, Grade 5=death. Serious AEs included death, a life-threatening AE, inpatient hospitalization or prolongation of existing hospitalization, persistent or significant disability or incapacity, a congenital anomaly or birth defect, or an important medical event that jeopardized the participant and required medical intervention to prevent 1 of the outcomes previously listed. TEAEs were any AE that emerged on or after the first dose, and within 30 days of the last dose. Serious and other non-serious AEs regardless of causality are reported in the AE module.

All participants who were enrolled and received at least 1 dose of study drug. Data were reported by dose group and where applicable the dose-escalation and expansion phases were combined to report data by dose group.

ORR was defined as percentage of participants with confirmed response (complete response [CR] + partial response [PR]). CR: Disappearance of all target or non-target lesions. All pathological or non-pathological lymph nodes (whether target or non-target) must have reduction in short axis to less than (<) 10 millimeters (mm). PR: At least 30 percent (%) decrease in the sum of the longest diameters (SLD) of target lesions, taking as reference the baseline SLD. The 95% confidence interval (CI) was based on binomial distribution.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose.

ORR was defined as percentage of participants with confirmed response (CR + PR). CR: Disappearance of all target or non-target lesions. All pathological or non-pathological lymph nodes (whether target or non-target) must have reduction in short axis to <10 mm. PR: At least 30% decrease in the SLD of target lesions, taking as reference the baseline SLD.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose.

PFS was defined as the time from the date of the first dose of study drug until the date of PD or death from any cause, whichever occurred first, estimated using the Kaplan-Meier method. PFS was defined based on radiological assessments and determined by the investigator. PD was defined as at least a 20% increase in the SLD of target lesions, taking as reference the smallest (nadir) SLD since and including baseline. In addition to the relative increase of 20%, the SLD must also demonstrate an absolute increase of at least 5 mm. Unequivocal progression of non-target lesions and appearance of new lesions. Unequivocal progression should not normally trump target lesion status. It must be representative of overall disease status change, not a single lesion increase.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose.

DOR was defined as the time from the date of the first response (CR or PR), to the date of PD or death from any cause, whichever occurred first. DOR was only defined for patients who had a best overall response of CR or PR, estimated using the Kaplan-Meier method. The response-evaluable population included all patients with radiographic assessment at baseline, who received at least 1 dose of combination treatment and had at least 1 post-dose radiographic tumor assessment or who died within 105 days of first dose.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose. Only participants who had best overall response of CR or PR were analyzable.

A CA-125 response was defined as a ≥ 50% reduction in CA-125 levels from baseline. GCIG CA125 response rate was defined as the number of participants with a CA-125 confirmed response divided by the number of participants in the CA-125 response-evaluable population multiplied by 100. The CA-125 evaluable population included all participants whose pretreatment sample was ≥2.0 times the upper limit of normal, within 2 weeks prior to the first dose of combination treatment, and who had at least 1 post-baseline CA-125 evaluation.

CA125 Evaluable Population: All participants whose pretreatment sample is ≥ 2.0 times the upper limit of normal (ULN), within 2 weeks prior to the first dose of combination treatment, and who have at least 1 post-baseline CA125 evaluation.

Blood samples from participants were analyzed to characterize the PK of mirvetuximab soravtansine when administered in 3- or 4-week cycles. Results are reported in micrograms/milliliter (µg/mL).

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose. The 'Number Analyzed' signifies participants evaluable for the specified categories.

Blood samples from participants were analyzed to characterize the PK of mirvetuximab soravtansine when administered in 3- or 4-week cycles. Results are reported in nanograms (ng)/mL.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose. The 'Number Analyzed' signifies participants evaluable for the specified categories.

Blood samples from participants were analyzed to characterize the PK of mirvetuximab soravtansine when administered in 3- or 4-week cycles. Results are reported in mg*hours (h)/mL.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose. The 'Number Analyzed' signifies participants evaluable for the specified categories.

Blood samples from participants were analyzed to characterize the PK of mirvetuximab soravtansine when administered in 3- or 4-week cycles. Note that '9999' is used because AUCinf cannot be calculated for n<3.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose. The 'Number Analyzed' signifies participants evaluable for the specified categories.

Blood samples from participants were analyzed to characterize the PK of mirvetuximab soravtansine when administered in 3- or 4-week cycles. PK parameters were calculated using standard non-compartmental methods.

The terminal t½ is an estimate (extrapolation) of the time it takes for the concentration or amount in the body of that drug to be reduced by exactly one-half (50%). If extrapolated AUC was greater than 20% (due to insufficient number of participants with data samples) the upper range of t½ was not reported.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose. The 'Number Analyzed' signifies participants evaluable for the specified categories.

Blood samples from participants were analyzed to characterize the PK of mirvetuximab soravtansine when administered in 3- or 4-week cycles.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose. The 'Number Analyzed' signifies participants evaluable for the specified categories.

Blood samples from participants were analyzed to characterize the PK of mirvetuximab soravtansine when administered in 3- or 4-week cycles.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose. The 'Number Analyzed' signifies participants evaluable for the specified categories.

Blood samples from participants were analyzed to characterize PK when administered in 3- or 4-week cycles.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose. The 'Number Analyzed' signifies participants evaluable for the specified categories.

Blood samples from participants were analyzed to characterize the PK of mirvetuximab soravtansine when administered in 3- or 4-week cycles.

PK parameters were derived using non-compartmental PK analysis.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose. The 'Number Analyzed' signifies participants evaluable for the specified categories.

Blood samples from participants at the end of infusion were analyzed to characterize the PK of mirvetuximab soravtansine when administered in 3- or 4-week cycles.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose. The 'Number Analyzed' signifies participants evaluable for the specified categories.

Blood samples from participants at the end of infusion were analyzed to characterize the PK of mirvetuximab soravtansine when administered in 3- or 4-week cycles.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose. The 'Number Analyzed' signifies participants evaluable for the specified categories.

Blood samples from participants at the end of infusion were analyzed to characterize the PK of mirvetuximab soravtansine when administered in 3- or 4-week cycles.

Response-Evaluable Population: All participants who received at least 1 dose of study treatment, had radiographic assessment at baseline received at least 1 dose of combination treatment, and at least 1 post-dose radiographic tumor assessment or have died within 105 days of first dose. The 'Number Analyzed' signifies participants evaluable for the specified categories.

Blood samples were collected to measure the presence of ADAs for mirvetuximab soravtansine. Seronegative is defined as a participant that tests negative at all visits. Treatment-emergent ADA is defined as a participant that is seronegative prior to dosing on Day 1 of Cycle 1 and tests positive in both screening and confirmatory assays at one or more subsequent visits. Treatment-unaffected ADA is defined as a participant test positive in both screening and confirmatory assays prior to dosing on Day 1 of Cycle 1 with a post-dose titer increase of less than or equal to 4-fold (based on a 2-fold sample dilution). Treatment-boosted ADA is defined as a participant test positive in both screening and confirmatory assays prior to dosing on Day 1 of Cycle 1 with a post-dose titer increase of more than a 4-fold increase (based on a 2-fold sample dilution).

The immunogenicity population included all participants who received at least 1 dose of study drug and have evaluable immunogenicity data. As per analysis plan, all regimens (arms/groups) were combined for each phase of the study (dose escalation and dose expansion) for analysis of ADA.