Characterization of folate receptor alpha (FRα) expression in archival tumor and biopsy samples from relapsed epithelial ovarian cancer patients: A phase I expansion study of the FRα-targeting antibody-drug conjugate mirvetuximab soravtansine.

To characterize folate receptor alpha (FRα) expression in archival and fresh biopsy tumor samples from relapsed ovarian cancer patients. Patients with ovarian tumors amenable to biopsy were eligible to enroll. Eligibility included a minimum requirement of FRα positivity in archival tumor samples (≥25% of cells with ≥2+ staining intensity). Patients received mirvetuximab soravtansine at 6mg/kg once every 3weeks. Core needle biopsies were collected before and after treatment and FRα levels assessed by immunohistochemistry. Descriptive statistics were used to summarize the association between receptor expression and response. Twenty-seven heavily pre-treated patients were enrolled. Six individuals (22%) did not have evaluable pre-treatment biopsies due to insufficient tumor cells. The concordance of FRα expression in archival and biopsy tissues was 71%, and no major shifts in receptor expression were seen in matched pre- and post-treatment biopsy samples. Adverse events were generally mild (≤grade 2) with keratopathy (48%), fatigue (44%), diarrhea, and blurred vision (each 37%) being the most common treatment-related toxicities. The confirmed objective response rate (ORR) was 22%, including two complete responses and four partial responses. Superior efficacy measures were observed in the subset of patients with the highest FRα levels (ORR, 31%; progression-free survival, 5.4months). Concordance of FRα expression in biopsy versus archival tumor samples suggests that archival tissue can reliably identify patients with receptor-positive tumors and is appropriate for patient selection in mirvetuximab soravtansine clinical trials. Regardless of the tissue source analyzed, higher FRα expression was associated with greater antitumor activity.

Martin LP ，Konner JA ，Moore KN ，Seward SM ，Matulonis UA ，Perez RP ，Su Y ，Berkenblit A ，Ruiz-Soto R ，Birrer MJ ... -  《-》

Phase Ib study of mirvetuximab soravtansine, a folate receptor alpha (FRα)-targeting antibody-drug conjugate (ADC), in combination with bevacizumab in patients with platinum-resistant ovarian cancer.

To evaluate the safety and clinical activity of mirvetuximab soravtansine, an antibody-drug conjugate comprising a humanized anti-folate receptor alpha (FRα) monoclonal antibody, cleavable linker, and the maytansinoid DM4, a potent tubulin-targeting agent, in combination with bevacizumab in patients with FRα-positive, platinum-resistant ovarian cancer. Patients with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer were administered mirvetuximab soravtansine (6 mg/kg, adjusted ideal body weight) and bevacizumab (15 mg/kg) once every 3 weeks. Eligibility included FRα positivity by immunochemistry and prior bevacizumab exposure was permitted. Adverse events, tumor response, and progression-free survival (PFS) were determined. Sixty-six patients, with a median of 3 prior lines of therapy (range, 1-8), received the combination of mirvetuximab soravtansine and bevacizumab at full dosing during the escalation and expansion stages of the study. Adverse events were generally mild-to-moderate (≤grade 2) with diarrhea, blurred vision, nausea, and fatigue being the most common treatment-related toxicities. Six cases of pneumonitis (9%; all grade 1 or 2), an adverse event of special interest, were observed. The confirmed objective response rate (ORR) was 39%, including 5 complete responses and 21 partial responses, and the median PFS was 6.9 months. The combination was particularly active in the subset of patients (n = 16) who were bevacizumab-naïve, less heavily pretreated (1-2 prior lines), and whose tumors exhibited medium/high FRα expression (ORR, 56% with a median duration of response of 12 months; PFS, 9.9 months). The combination of mirvetuximab soravtansine with bevacizumab is well tolerated in patients with platinum-resistant, recurrent ovarian cancer. The encouraging efficacy measures compare favorably to reported outcomes for bevacizumab combined with standard chemotherapy in similar patient populations.

O'Malley DM ，Matulonis UA ，Birrer MJ ，Castro CM ，Gilbert L ，Vergote I ，Martin LP ，Mantia-Smaldone GM ，Martin AG ，Bratos R ，Penson RT ，Malek K ，Moore KN ... -  《-》

Safety and activity findings from a phase 1b escalation study of mirvetuximab soravtansine, a folate receptor alpha (FRα)-targeting antibody-drug conjugate (ADC), in combination with carboplatin in patients with platinum-sensitive ovarian cancer.

To evaluate the safety profile and preliminary antitumor activity of mirvetuximab soravtansine when administered in combination with carboplatin to relapsed ovarian cancer patients. Patients with recurrent, platinum-sensitive epithelial ovarian or fallopian tube cancer were enrolled. Eligibility included a minimum requirement of tumor FRα positivity (≥25% of cells with ≥2+ staining intensity). Patients received escalating doses of mirvetuximab soravtansine and carboplatin on day 1 of a 21-day cycle (once every 3 weeks). Mirvetuximab soravtansine maintenance therapy was permitted, at the investigators discretion, following cessation of carboplatin treatment. Adverse events, tumor response, and progression-free survival (PFS) were determined. Eighteen patients were enrolled and dosed with combination therapy; thirteen continued with mirvetuximab soravtansine maintenance following carboplatin discontinuation. Mirvetuximab soravtansine dosing was escalated from 5 to 6 mg/kg (adjusted ideal body weight) and carboplatin from AUC4 to AUC5. Adverse events were generally mild (≤ grade 2) with nausea, diarrhea, thrombocytopenia, blurred vision, and fatigue being the most common treatment-emergent toxicities. For all evaluable patients (n = 17), the confirmed objective response rate (ORR) was 71%, including three complete responses and nine partial responses, and the median PFS was 15 months. A median duration of response was not reached. These data demonstrate that mirvetuximab soravtansine combined with carboplatin is a well-tolerated and highly active regimen in recurrent, platinum-sensitive ovarian cancer. Further evaluation of this combination in a randomized fashion is warranted.

Moore KN ，O'Malley DM ，Vergote I ，Martin LP ，Gonzalez-Martin A ，Malek K ，Birrer MJ ... -  《-》

Safety and Activity of Mirvetuximab Soravtansine (IMGN853), a Folate Receptor Alpha-Targeting Antibody-Drug Conjugate, in Platinum-Resistant Ovarian, Fallopian Tube, or Primary Peritoneal Cancer: A Phase I Expansion Study.

Moore KN ，Martin LP ，O'Malley DM ，Matulonis UA ，Konner JA ，Perez RP ，Bauer TM ，Ruiz-Soto R ，Birrer MJ ... -  《-》

Phase 1b study of mirvetuximab soravtansine, a folate receptor alpha (FRα)-targeting antibody-drug conjugate, in combination with carboplatin and bevacizumab in patients with platinum-sensitive ovarian cancer.

Evaluate the antitumor activity and safety profile of the triplet combination of mirvetuximab soravtansine (MIRV), carboplatin, and bevacizumab in recurrent, platinum-sensitive ovarian cancer. Participants with recurrent, platinum-sensitive epithelial ovarian, fallopian tube, or primary peritoneal cancer (1-2 prior lines of therapy) received MIRV (6 mg/kg adjusted ideal body weight), carboplatin (AUC5), and bevacizumab (15 mg/kg) once every 3 weeks. Carboplatin could be discontinued after 6 cycles per investigator discretion; continuation of MIRV+bevacizumab as maintenance therapy was permitted. Eligibility included folate receptor alpha (FRα) expression by immunohistochemistry (≥50% of cells with ≥2+ intensity; PS2+ scoring); prior bevacizumab was allowed. Tumor response, duration of response (DOR), progression-free survival (PFS), and adverse events (AEs) were assessed. Forty-one participants received triplet therapy, with a median of 6, 12, and 13 cycles of carboplatin, MIRV, and bevacizumab, respectively. The confirmed objective response rate was 83% (9 complete and 25 partial responses). The median DOR was 10.9 months; median PFS was 13.5 months. AEs (any grade) occurred as expected, based on each agent's safety profile; most common were diarrhea (83%), nausea (76%), fatigue (73%), thrombocytopenia (71%), and blurred vision (68%). Most cases were mild to moderate (grade ≤2), except for thrombocytopenia, for which most drug-related discontinuations occurred, and neutropenia. This triplet regimen (MIRV+carboplatin+bevacizumab) was highly active, with a tolerable AE profile in participants with recurrent, platinum-sensitive, FRα-expressing ovarian cancer. Thrombocytopenia was the primary cause of dose modifications. These outcomes compare favorably to historical data reported for platinum-based chemotherapy plus bevacizumab regimens in similar patient populations.

Richardson DL ，Moore KN ，Vergote I ，Gilbert L ，Martin LP ，Mantia-Smaldone GM ，Castro CM ，Provencher D ，Matulonis UA ，Stec J ，Wang Y ，Method M ，O'Malley DM ... -  《-》