Farletuzumab, a monoclonal antibody directed against folate receptor alpha, shows no evidence of teratogenicity in cynomolgus monkeys.

Farletuzumab is a humanized monoclonal antibody targeting human folate receptor alpha, which is being developed as an anti-cancer drug. A non-human primate reproductive study was conducted to evaluate whether it could cause any embryonic or fetal abnormalities. Farletuzumab was administered intravenously to pregnant cynomolgus monkeys (n = 16/group) at doses of 0 or 67.5 mg/kg once weekly during gestation day (GD) 20 through 97. C-section was performed on GD100 ±â€¯2, and fetuses were evaluated for morphologic (external, visceral and skeletal) effects. No farletuzumab-related changes were observed in maternal animals or fetuses, which are supported by the fact that farletuzumab has no effects on cellular uptake of folate. These data support the potential use of farletuzumab for oncologic indications during pregnancy.

CA125 suppresses amatuximab immune-effector function and elevated serum levels are associated with reduced clinical response in first line mesothelioma patients.

The tumor-shed antigen CA125 has recently been found to bind certain monoclonal antibodies (mAbs) and suppress immune-effector mediated killing through perturbation of the Fc domain with CD16a and CD32a Fc-γ activating receptors on immune-effector cells. Amatuximab is a mAb targeting mesothelin whose mechanism of action utilizes in part antibody-dependent cellular cytotoxicity (ADCC). It is being tested for its therapeutic activity in patients with mesothelioma in combination with first line standard-of-care. To determine if CA125 has immunosuppressive effects on amatuximab ADCC and associated clinical outcomes, post hoc subgroup analysis of patients from a Phase 2 study with primary diagnosed stage III/IV unresectable mesothelioma treated with amatuximab plus cisplatin and pemetrexed were conducted. Analysis found patients with baseline CA125 levels no greater than 57 U/m (∼3X the upper limit of normal) had a 2 month improvement in progression free survival (HR = 0.43, p = 0.0062) and a 7 month improvement in overall survival (HR = 0.40, p = 0.0022) as compared to those with CA125 above 57 U/mL. In vitro studies found that CA125 was able to bind amatuximab and perturb ADCC activity via decreased Fc-γ-receptor engagement. These data suggest that clinical trial designs of antibody-based drugs in cancers producing CA125, including mesothelioma, should consider stratifying patients on baseline CA125 levels for mAbs that are experimentally determined to be bound by CA125.

A phase 2 study of ontuxizumab, a monoclonal antibody targeting endosialin, in metastatic melanoma.

Objectives Ontuxizumab (MORAB-004) is a first-in-class monoclonal antibody that interferes with endosialin function, which is important in tumor stromal cell function, angiogenesis, and tumor growth. This Phase 2 study evaluated the 24-week progression-free survival (PFS) value, pharmacokinetics, and tolerability of 2 doses of ontuxizumab in patients with metastatic melanoma. Patients and methods Patients with metastatic melanoma and disease progression after receiving at least 1 prior systemic treatment were randomized to receive ontuxizumab (2 or 4 mg/kg) weekly, without dose change, until disease progression. Results Seventy-six patients received at least 1 dose of ontuxizumab (40 received 2 mg/kg, 36 received 4 mg/kg). The primary endpoint, 24-week PFS value, was 11.4% (95% Confidence Interval [CI]: 5.3%-19.9%) for all patients (13.5% for 2 mg/kg and 8.9% for 4 mg/kg). The median PFS for all patients was 8.3 weeks (95% CI: 8.1-12.3 weeks). One patient receiving 4 mg/kg had a partial response, as measured by Response Evaluation Criteria in Solid Tumors v1.1. Twenty-seven of 66 response evaluable patients (40.9%) had stable disease. The median overall survival was 31.0 weeks (95% CI: 28.3-44.0 weeks). The most common adverse events overall were headache (55.3%), fatigue (48.7%), chills (42.1%), and nausea (36.8%), mostly grade 1 or 2. Conclusions Ontuxizumab at both doses was well tolerated. The 24-week PFS value was 11.4% among all ontuxizumab-treated patients. The overall response rate was 3.1% at the 4 mg/kg dose, with clinical benefit achieved in 42.4% of response evaluable patients. Efficacy of single-agent ontuxizumab at these doses in melanoma was low.

A Randomized, Double-Blind, Placebo-Controlled Phase II Study of the Efficacy and Safety of Monotherapy Ontuxizumab (MORAb-004) Plus Best Supportive Care in Patients with Chemorefractory Metastatic Colorectal Cancer.

Purpose: The purpose of this study was to evaluate the safety and efficacy of ontuxizumab (MORAb-004), a monoclonal antibody that interferes with endosialin (tumor endothelial marker-1) function, in patients with chemorefractory metastatic colorectal cancer and to identify a responsive patient population based on biomarkers.Experimental Design: This was a randomized, double-blind, placebo-controlled, phase II study. Patients were randomly assigned in a 2:1 ratio to receive weekly intravenous ontuxizumab (8 mg/kg) or placebo plus best supportive care until progression or unacceptable toxicity. Tissue and blood biomarkers were evaluated for their ability to identify a patient population that was responsive to ontuxizumab.Results: A total of 126 patients were enrolled. No significant difference between the ontuxizumab and placebo groups was evident for the primary endpoint of progression-free survival (PFS), with a median PFS of 8.1 weeks in each group (HR, 1.13; 95% confidence interval, 0.76-1.67; P = 0.53). There were no significant differences between groups for overall survival (OS) or overall response rate (ORR). The most common treatment-emergent adverse events (TEAEs) in the ontuxizumab group (vs. the placebo group, respectively) were fatigue (53.7% vs. 47.5%), nausea (39.0% vs. 35.0%), decreased appetite (34.1% vs. 27.5%), and constipation (28.0% vs. 32.5%). The most common grade 3/4 TEAE in the ontuxizumab group versus placebo was back pain (11.0% vs. 0%). No single biomarker clearly identified patients responsive to ontuxizumab.Conclusions: No benefit with ontuxizumab monotherapy compared with placebo for clinical response parameters of PFS, OS, or ORR was demonstrated. Ontuxizumab was well tolerated. Clin Cancer Res; 24(2); 316-25. ©2017 AACR.

FCGR2A and FCGR3A Genotypes Correlate with Farletuzumab Response in Patients with First-Relapsed Ovarian Cancer Exhibiting Low CA125.

Farletuzumab is a humanized monoclonal antibody that binds to folate receptor alpha and elicits an anti-tumor response via immune effector activity. Recent studies from a global phase 3 trial in ovarian cancer patients treated with carboplatin/taxane plus farletuzumab found that the tumor-produced CA125 protein can suppress farletuzumab function via perturbing its engagement to the activating Fc-γ receptors CD32a (FCGR2A) and CD16a (FCGR3A). Previous reports have indicated that naturally occurring polymorphisms in both of these receptors may play a role in their ability to engage therapeutic antibodies and elicit an optimal immune response via antibody-dependent cellular cytotoxicity (ADCC). In light of the importance of farletuzumab ADCC function for optimal tumor cell killing, we evaluated the frequency of FCGR2A-131H/R and FCGR3A-158V/F polymorphisms in 461 consenting patients from this global clinical study and their association with clinical outcome to placebo versus farletuzumab treatment. Here, we show that farletuzumab has enhanced binding to FCGR3A-158V high-affinity receptor and has an enhanced clinical outcome in patients with low baseline CA125 levels and at least 1 high-affinity allele of FCGR2A or FCGR3A.

Tumor antigen CA125 suppresses antibody-dependent cellular cytotoxicity (ADCC) via direct antibody binding and suppressed Fc-γ receptor engagement.

Cancers employ a number of mechanisms to evade host immune responses. Here we report the effects of tumor-shed antigen CA125/MUC16 on suppressing IgG1-mediated antibody-dependent cellular cytotoxicity (ADCC). This evidence stems from prespecified subgroup analysis of a Phase 3 clinical trial testing farletuzumab, a monoclonal antibody to folate receptor alpha, plus standard-of-care carboplatin-taxane chemotherapy in patients with recurrent platinum-sensitive ovarian cancer. Patients with low serum CA125 levels treated with farletuzumab demonstrated improvements in progression free survival (HR 0.49, p = 0.0028) and overall survival (HR 0.44, p = 0.0108) as compared to placebo. Farletuzumab's pharmacologic activity is mediated in part through ADCC. Here we show that CA125 inhibits ADCC by directly binding to farletuzumab that in turn perturbs Fc-γ receptor engagement on effector cells.

Correlation of FCGRT genomic structure with serum immunoglobulin, albumin and farletuzumab pharmacokinetics in patients with first relapsed ovarian cancer.

Farletuzumab (FAR) is a humanized monoclonal antibody (mAb) that binds to folate receptor alpha. A Ph3 trial in ovarian cancer patients treated with carboplatin/taxane plus FAR or placebo did not meet the primary statistical endpoint. Subgroup analysis demonstrated that subjects with high FAR exposure levels (Cmin>57.6µg/mL) showed statistically significant improvements in PFS and OS. The neonatal Fc receptor (fcgrt) plays a central role in albumin/IgG stasis and mAb pharmacokinetics (PK). Here we evaluated fcgrt sequence and association of its promoter variable number tandem repeats (VNTR) and coding single nucleotide variants (SNV) with albumin/IgG levels and FAR PK in the Ph3 patients. A statistical correlation existed between high FAR Cmin and AUC in patients with the highest quartile of albumin and lowest quartile of IgG1. Analysis of fcgrt identified 5 different VNTRs in the promoter region and 9 SNVs within the coding region, 4 which are novel.

A Randomized, Double-Blind, Placebo-Controlled, Phase III Study to Assess Efficacy and Safety of Weekly Farletuzumab in Combination With Carboplatin and Taxane in Patients With Ovarian Cancer in First Platinum-Sensitive Relapse.

PURPOSE: Farletuzumab is a humanized monoclonal antibody that binds to folate receptor-α, which is highly expressed in ovarian carcinoma and largely absent from normal tissue. Farletuzumab was investigated in a double-blind, randomized phase III study in platinum-sensitive ovarian cancer. PATIENTS AND METHODS: Eligible patients had first recurrent ovarian cancer 6-24 months following completion of platinum-taxane chemotherapy. All patients received carboplatin plus paclitaxel or docetaxel (for six cycles combined with randomly assigned test products in a 1:1:1 ratio: farletuzumab 1.25 mg/kg, farletuzumab 2.5 mg/kg, or placebo). The single-agent test product was continued weekly until disease progression. The primary end point was progression-free survival (PFS) by Response Evaluation Criteria in Solid Tumors. Additional analyses not outlined in the original protocol were prespecified in the final statistical analysis plan, including a subgroup analysis by baseline CA-125 and farletuzumab exposure levels. RESULTS: A total of 1,100 women were randomly assigned to treatment dose or placebo. PFS from the primary analysis was 9.0, 9.5, and 9.7 months for the placebo, farletuzumab 1.25 mg/kg, and farletuzumab 2.5 mg/kg groups, respectively. Neither farletuzumab group was statistically different from the placebo group (hazard ratio [HR], 0.99 [95% CI, 0.81 to 1.21] and 0.86 [95% CI, 0.70 to 1.06] for farletuzumab 1.25 mg/kg and 2.5 mg/kg group v placebo, respectively). In the prespecified subgroup, baseline CA-125 levels not more than three times the upper limit of normal (ULN) correlated with longer PFS (HR, 0.49; P = .0028) and overall survival (OS) (HR, 0.44; P = .0108) for farletuzumab 2.5 mg/kg versus placebo. Subgroup analysis of farletuzumab exposure above the median, regardless of dose, showed significantly better PFS versus placebo. The most common adverse events were those associated with chemotherapy. CONCLUSION: Neither farletuzumab dose met the study's primary PFS end point. Prespecified subgroup analyses demonstrated that patients with CA-125 levels not more than three times the ULN and patients with higher farletuzumab exposure showed superior PFS and OS compared with placebo.

Phase 1b safety study of farletuzumab, carboplatin and pegylated liposomal doxorubicin in patients with platinum-sensitive epithelial ovarian cancer.

OBJECTIVE: Farletuzumab is a humanized monoclonal antibody that binds to folate receptor alpha, over-expressed in epithelial ovarian cancer (EOC) but largely absent in normal tissue. Previously, carboplatin plus pegylated liposomal doxorubicin showed superior progression-free survival and an improved therapeutic index compared with carboplatin/paclitaxel in relapsed platinum-sensitive EOC. This study assessed safety of farletuzumab/carboplatin/pegylated liposomal doxorubicin in women with platinum-sensitive recurrent EOC. METHODS: This multicenter, single-arm study enrolled patients with platinum-sensitive EOC in first or second relapse for treatment with weekly farletuzumab 2.5mg/kg plus carboplatin AUC5-6 and pegylated liposomal doxorubicin 30mg/m(2) every 4weeks for 6cycles. Subsequently, maintenance with single-agent farletuzumab 2.5mg/kg once weekly or farletuzumab 7.5mg/kg once every three weeks continued until progression. The primary objective was to assess the safety of farletuzumab/carboplatin/pegylated liposomal doxorubicin. RESULTS: Fifteen patients received a median of 12.0cycles (range, 3-26) of farletuzumab as combination therapy or maintenance, for a median of 45.0weeks (range 9-95). Farletuzumab/carboplatin/pegylated liposomal doxorubicin was generally well tolerated, with no farletuzumab-related grades 3-4 adverse events. The most commonly reported adverse events were associated with combination chemotherapy: fatigue (73.3%), nausea (46.7%), and neutropenia (40%). Ten patients had grade ≥3 adverse events, most frequently neutropenia and fatigue. No cardiac toxicity was seen. Best overall responses (RECIST) were a complete response for one patient, partial responses for 10 patients, and stable disease for four patients. CONCLUSIONS: Farletuzumab plus carboplatin/pegylated liposomal doxorubicin in women with platinum-sensitive EOC demonstrated a safety profile consistent with that of carboplatin plus pegylated liposomal doxorubicin.

Population pharmacokinetics of farletuzumab, a humanized monoclonal antibody against folate receptor alpha, in epithelial ovarian cancer.

PURPOSE: The purpose of this analysis was to develop a population pharmacokinetic model for farletuzumab, a humanized immunoglobulin (Ig)G(1) monoclonal antibody (mAb) to the folate receptor alpha, which is a receptor over-expressed in ovarian cancer, but largely absent from normal tissue. METHODS: In total, 2,472 samples were included in the building of the pharmacokinetic model. Farletuzumab 12.5-400 mg/m(2) had been administered via intravenous infusion to 79 patients with advanced ovarian cancer enrolled in one of the two clinical studies. Data were analyzed by a nonlinear mixed-effects modeling approach. RESULTS: Farletuzumab pharmacokinetics was best described by a two-compartment model with first-order (linear) elimination. In the final model, estimated values of clearance and volume of distribution of the central compartment were 0.00784 l/h and 3.00 l, respectively. Body weight was the only covariate investigated that explained inter-patient variability in clearance and the central volume of distribution. There was no effect of age, human anti-human antibodies, or concomitant chemotherapy on the pharmacokinetics of farletuzumab. Simulations showed that, when the mg/kg/week dose was maintained, steady-state exposure to farletuzumab was similar with dosing every week or every 3 weeks. CONCLUSIONS: The pharmacokinetic parameters of farletuzumab are similar to those of other IgG mAbs. The results support weight-based dosing of farletuzumab on a weekly or 3-weekly schedule.

Phase I clinical trial of the chimeric anti-mesothelin monoclonal antibody MORAb-009 in patients with mesothelin-expressing cancers.

PURPOSE: MORAb-009 is a chimeric monoclonal antibody that targets mesothelin, a tumor differentiation antigen overexpressed in pancreatic cancer, ovarian cancer, mesothelioma, and other malignancies. We conducted a phase I clinical trial of MORAb-009 in patients with advanced mesothelin-expressing cancers to determine its safety, dose-limiting toxicity (DLT), and maximum tolerated dose (MTD). METHODS: Cohorts consisting of 3 to 6 subjects each received MORAb-009 intravenously on days 1, 8, 15, and 22 at progressively increasing doses ranging from 12.5 to 400 mg/m(2). Disease evaluation with computed tomography occurred on day 35. Subjects with responding or stable disease could receive additional cycles of MORAb-009. RESULTS: A total of 24 subjects were treated including 13 mesothelioma, 7 pancreatic cancer, and 4 ovarian cancer patients. The median number of MORAb-009 infusions was 4 (range 1-24 infusions). At the 400 mg/m(2) dose level, 2 subjects experienced DLT (grade 4 transaminitis and a grade 3 serum sickness). Thus, although there were other contributing causes of these adverse events, 200 mg/m(2) was considered the MTD. Other adverse events at least possibly related to MORAb-009 included 7 drug hypersensitivity events (all grade 1 or 2) and a thromboembolic event (grade 4). Eleven subjects had stable disease. There was a dose-dependent increase in serum MORAb-009 concentration. CONCLUSION: MORAb-009 is well tolerated and the MTD when administered weekly is conservatively set at 200 mg/m(2). In this group of previously treated patients, 11 subjects had stable disease. Phase II studies of MORAb-009 in different mesothelin-expressing cancers are ongoing.

Farletuzumab, a humanized monoclonal antibody against folate receptor alpha, in epithelial ovarian cancer: a phase I study.

PURPOSE: Folate receptor α expression is highly restricted in normal adult tissues but upregulated in a wide range of human cancer types, including epithelial ovarian cancer. Farletuzumab, a humanized monoclonal antibody against folate receptor α, has shown antitumor activity and favorable toxicity in preclinical evaluation. This phase I, dose-escalation study was conducted to determine the safety of weekly i.v. farletuzumab and establish the maximum tolerated dose (MTD). EXPERIMENTAL DESIGN: Patients with platinum-refractory or platinum-resistant epithelial ovarian cancer received farletuzumab (12.5-400 mg/m(2)) on days 1, 8, 15, and 22 of a 5-week cycle. Intrapatient dose escalation was not permitted. Dose-limiting toxicity (DLT) was defined by treatment-related adverse event of grade 3 or higher, and the MTD was the highest dose at which one or none of six patients experienced a DLT. Disease progression was recorded using Response Evaluation Criteria in Solid Tumors criteria and serum CA-125. RESULTS: Twenty-five heavily pretreated patients were included in the safety, efficacy, and pharmacokinetic analyses. No DLTs or MTDs were encountered, and dose escalation was continued to farletuzumab 400 mg/m(2). C(max) and AUC(0-24) (area under the serum concentration-time curve) increased in an approximately dose-proportional manner, and a nuclear imaging substudy confirmed tumor targeting. There were no objective responses. Stable disease by Response Evaluation Criteria in Solid Tumors was observed in nine (36%) patients and CA-125 reduction in four. Three patients received continued therapy and completed a total of up to three cycles. CONCLUSIONS: In this phase I study, farletuzumab administered as an i.v. infusion at doses of 12.5 to 400 mg/m(2) was generally safe and well tolerated in the management of heavily pretreated patients with epithelial ovarian cancer.

Inhibition of mesothelin-CA-125 interaction in patients with mesothelioma by the anti-mesothelin monoclonal antibody MORAb-009: Implications for cancer therapy.

BACKGROUND: Mesothelin, a tumor differentiation antigen highly expressed in mesothelioma and ovarian cancer, is the receptor for CA-125 (MUC 16) and this interaction may play a role in tumor metastasis. MORAb-009 is a chimeric anti-mesothelin monoclonal antibody. METHODS: Twenty-four patients with mesothelin expressing cancers were treated on a phase I study of MORAb-009 administered as an intravenous infusion (12.5-400mg/m(2)) weeklyx4 doses with 2 weeks off before the next cycle. This report summarizes the effect of MORAb-009 on serum CA-125 kinetics in the eight patients with mesothelioma who had CA-125 levels measured before and at different time-points following therapy. RESULTS: MORAb-009 treatment led to a marked increase in serum CA-125 levels in all patients including those without elevated CA-125 levels before therapy. The increase in CA-125 levels was not due to disease progression since CA-125 levels decreased rapidly after stopping MORAb-009 therapy. No patients had signs of peritoneal or pleural inflammation as the possible cause of CA-125 rise. In addition, the elevated CA-125 levels were not due to MORAb-009 interfering with the laboratory assay used to measure CA-125. CONCLUSION: The increase in serum CA-125 produced by treatment with MORAb-009 is most likely due to MORAb-009 inhibiting the binding of tumor shed CA-125 to mesothelin present on mesothelial cells lining the pleural and peritoneal cavities. Inhibiting the mesothelin-CA-125 interaction could be a useful strategy to prevent tumor metastasis in mesotheliomas and ovarian cancer.