Clinical Pharmacology for Elahere
Mechanism Of Action
Mirvetuximab soravtansine-gynx is an antibody-drug conjugate (ADC). The antibody is a chimeric IgG1 directed against folate receptor alpha (FRα). The small molecule, DM4, is a microtubule inhibitor attached to the antibody via a cleavable linker. Upon binding to FRα, mirvetuximab soravtansine-gynx is internalized followed by intracellular release of DM4 via proteolytic cleavage. DM4 disrupts the microtubule network within the cell, resulting in cell cycle arrest and apoptotic cell death.
Pharmacodynamics
Exposure-Response Relationships
Higher exposure to mirvetuximab soravtansine-gynx was associated with higher overall response rates and longer median PFS and OS; higher exposure to mirvetuximab soravtansine-gynx was also associated with higher incidence of ocular adverse reactions as well as marginally increased peripheral neuropathy.
Cardiac Electrophysiology
At the approved recommended dose, ELAHERE did not cause large mean increases (>10 msec) in the QTc interval.
Pharmacokinetics
The pharmacokinetics were characterized in patients who received mirvetuximab soravtansine-gynx 0.16 mg/kg to 8.7 mg/kg adjusted ideal body weight (AIBW) (0.03 times to 1.4 times the approved recommended dose of 6 mg/kg AIBW), unless otherwise noted.
Table 8 summarizes the exposure parameters of mirvetuximab soravtansine-gynx, unconjugated DM4, and its metabolite S-methyl-DM4 following administration after the first cycle (3-weeks). Peak mirvetuximab soravtansine-gynx concentrations were observed near the end of intravenous infusion, while peak unconjugated DM4 concentrations were observed on the second day after administration and the peak S-methyl-DM4 concentrations were observed approximately 3 days after administration. Steady state concentrations of mirvetuximab soravtansine-gynx, DM4, and S-methyl-DM4 were reached after one 3-week cycle. Accumulation of the mirvetuximab soravtansine-gynx, DM4, and S-methyl-DM4 was minimal following multiple cycles.
Table 8: Exposure Parameters of Mirvetuximab Soravtansine-gynx, Unconjugated DM4, and S-methyl DM4 After First Cycle at a Dosage of 6 mg/kg
|
Mirvetuximab Soravtansine-gynx
Mean (±SD) |
Unconjugated DM4
Mean (±SD) |
S-methyl-DM4
Mean (±SD) |
| Cmax |
137.3 (±62.3) μg/mL |
4.1 (±2.3) ng/mL |
7.0 (±6.8) ng/mL |
| AUCtau |
20.6 (±6.8) h*mg/mL |
530 (±245) h*ng/mL |
1848 (±1585) h*ng/mL |
| Cmax = maximum concentration, AUCtau = area under the concentration vs. time curve over the dosing interval (21 days). |
Distribution
The mean (±SD) steady state volume of distribution of mirvetuximab soravtansine-gynx was 2.6 (±2.9) L. Human plasma protein binding of DM4 and S-methyl DM4 was >99%, in vitro.
Elimination
For mirvetuximab soravtansine-gynx, total plasma clearance (mean [CV%]) of was 19 mL/hour (52%) and the mean terminal phase half-life after the first dose was 4.8 days leading to a steady state at approximately 24 days.
For the unconjugated DM4, the total plasma clearance (mean [CV%]) was 14 L/hour (31%) and the mean terminal phase half-life was 2.8 days.
For S-methyl-DM4, the total plasma clearance (mean [CV%]) was 4.3 L/hour (64%) and the mean terminal phase half-life was 5 days.
Metabolism
The monoclonal antibody portion of mirvetuximab soravtansine-gynx is expected to be metabolized into small peptides by catabolic pathways. Unconjugated DM4 and S-methyl-DM4 undergo metabolism by CYP3A4. In human plasma, DM4 and S-methyl DM4 were identified as the main circulating metabolites, accounting for approximately 0.4% and 1.4% of mirvetuximab soravtansine-gynx AUC, respectively.
Excretion
S-methyl DM4 and DM4-sulfo-SPDB-lysine were detected in urine within 24 hours of infusion as the main metabolites.
Specific Populations
No clinically significant differences in the pharmacokinetics of mirvetuximab soravtansine-gynx were observed based on age (32 to 89 years), race (White, Black, or Asian), body weight (36 to 136 kg), mild hepatic impairment (total bilirubin ≤ULN and any AST >ULN or total bilirubin >1 to 1.5 times ULN and any AST), or mild to moderate renal impairment (CLcr 30 to 89 mL/min).
The pharmacokinetics of mirvetuximab soravtansine-gynx in patients with moderate to severe hepatic impairment (total bilirubin >1.5 ULN with any AST) or severe renal impairment (CLcr 15 to 30 mL/min) is unknown.
Drug Interaction Studies
Clinical Studies And Model Informed Approaches
No clinical studies to evaluate the drug-drug interaction potential of mirvetuximab soravtansine-gynx were conducted.
There were no differences in exposure between patients who received concomitant weak or moderate CYP3A4 inhibitors or P-glycoprotein (P-gp) inhibitors and those who did not.
In Vitro Studies
Cytochrome P450 (CYP) Enzymes
Unconjugated DM4 is a time-dependent inhibitor of CYP3A4. Unconjugated DM4 and S-methyl DM4 are not inhibitors of CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, or CYP3A. DM4 and S-methyl DM4 are not inducers of CYP1A2, CYP2B6, or CYP3A4.
Transporter Systems
Unconjugated DM4 and S-methyl DM4 are substrates of P-gp but are not inhibitors of Pgp.
Immunogenicity
The observed incidence of anti-drug antibodies (ADA), including neutralizing antibody, is highly dependent on the sensitivity and specificity of the assay. Differences in assay methods preclude meaningful comparisons of the incidence of ADAs in the studies described below with the incidence of ADAs to mirvetuximab soravtansine-gynx in other studies.
With a median treatment duration of 4.4 months in Studies 0416, 0417, 0401, and 0403, in patients with epithelial ovarian, fallopian tube, or primary peritoneal cancer who received mirvetuximab soravtansine-gynx at 6 mg/kg AIBW intravenously every 3 weeks, 9% (57/626) of patients developed anti-mirvetuximab soravtansine-gynx antibodies. Neutralizing antibodies were detected in 47% (27/57) of patients who were ADA-positive.
No clinically meaningful difference was observed in the trough concentrations of mirvetuximab soravtansinegynx between ADA-positive and ADA-negative patients. Anti-mirvetuximab soravtansine-gynx antibody formation was associated with a higher incidence of infusion-related reactions [see ADVERSE REACTIONS]. The effect of anti-drug antibodies on effectiveness has not been fully characterized. Based on limited data, the presence of anti-mirvetuximab soravtansine-gynx antibodies may be associated with decreased efficacy in ADA-positive patients when compared to ADA-negative patients.
Clinical Studies
Study 0416
The efficacy of ELAHERE was evaluated in Study 0416 (MIRASOL, NCT04209855), a multicenter, open-label, active-controlled, randomized, two-arm, trial in patients (n=453) with FRα positive, platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer. Patients were permitted to receive up to three prior lines of systemic therapy. The trial enrolled patients whose tumors were positive for FRα expression as determined by the VENTANA FOLR1 (FOLR1-2.1) RxDx Assay. Patients were excluded if they had corneal disorders, ocular conditions requiring ongoing treatment, Grade >1 peripheral neuropathy, or noninfectious interstitial lung disease.
Patients were randomized (1:1) to receive ELAHERE 6 mg/kg (based on adjusted ideal body weight) as an intravenous infusion every 3 weeks or investigator"fs choice of chemotherapy (paclitaxel, pegylated liposomal doxorubicin [PLD], or topotecan) until disease progression or unacceptable toxicity. Tumor response assessments occurred every 6 weeks for the first 36 weeks and every 12 weeks thereafter. Randomization was stratified by the following factors: number of prior lines of therapy (1 vs. 2 vs. 3) and chemotherapy (paclitaxel vs. PLD vs. topotecan) chosen prior to randomization.
The major efficacy outcome measures were investigator-assessed progression-free survival (PFS), confirmed overall response rate (ORR), and overall survival (OS). PFS and ORR were evaluated according to Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1.
The median age was 63 years (range: 29 to 88); 66% were White, 12% were Asian, 3% were Black or African American, and 18% did not have race reported. Six percent of patients were Hispanic or Latino. Nearly all patients had an ECOG PS of 0 (55%) or 1 (44%). Fourteen percent of patients had received 1 prior line of systemic therapy, 39% of patients had received 2 prior lines of systemic therapy, and 47% of patients had received 3 prior lines of systemic therapy. Thirty-seven percent of patients received prior systemic therapy for platinum-resistant disease. Sixty-two percent of patients received prior bevacizumab and 55% had received a prior PARP inhibitor.
ELAHERE demonstrated a statistically significant improvement in PFS, ORR, and OS for patients randomized to ELAHERE as compared with chemotherapy.
Efficacy results for Study 0416 are summarized in Table 9 and Figures 1 and 2.
Table 9: Efficacy Results in Study 0416
|
ELAHERE
n=227 |
Chemotherapy*
n=226 |
| Progression-free survival (PFS) |
| Number (%) of patients with events |
176 (78) |
166 (73) |
| Median, months (95% CI) |
5.6 (4.3, 5.9) |
4.0 (2.9, 4.5) |
| Hazard ratio (95% CI) |
0.65 (0.52, 0.81) |
| p-valuea |
<0.0001 |
| Overall Survival (OS) |
| Number (%) of patients with events |
90 (40) |
114 (50) |
| Median, months (95% CI) |
16.5 (14.5, 24.6) |
12.7 (10.9, 14.4) |
| Hazard Ratio (95% CI) |
0.67 (0.50, 0.88) |
| p-valuea |
0.0046 |
| Confirmed overall response rate (ORR) |
| Number of patients with measurable disease at baseline |
225 |
224 |
| ORR (95% CI) |
42% (36, 49) |
16% (12, 22) |
| Complete response |
5% |
0% |
| Partial response |
37% |
16% |
| p-valueb |
<0.0001 |
* Chemotherapy: paclitaxel, PLD, or topotecan.
a Two-sided p-value based on stratified log-rank test.
b Two-sided p-value based upon Cochran-Mantel-Haenszel (CMH) test. |
Figure 1: Kaplan-Meier Curve for Progression-free Survival in Study 0416
Figure 2: Kaplan-Meier Curve for Overall Survival in Study 0416
Study 0417
The efficacy of ELAHERE was evaluated in Study 0417 (SORAYA, NCT04296890), a single-arm trial of patients with FRα positive, platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer (n=106). Patients were permitted to receive up to three prior lines of systemic therapy. All patients were required to have received prior bevacizumab. The trial enrolled patients whose tumors were positive for FRα expression as determined by the VENTANA FOLR1 (FOLR1-2.1) RxDx Assay. Patients were excluded if they had corneal disorders, ocular conditions requiring ongoing treatment, Grade >1 peripheral neuropathy, or noninfectious interstitial lung disease.
Patients received ELAHERE 6 mg/kg (based on adjusted ideal body weight) as an intravenous infusion every 3 weeks until disease progression or unacceptable toxicity. Tumor response assessments occurred every 6 weeks for the first 36 weeks and every 12 weeks thereafter. The major efficacy outcome measures were investigator-assessed overall response rate (ORR) and duration of response (DOR) evaluated according to Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1.
The efficacy evaluable population included 104 patients with platinum-resistant disease, who had measurable disease, and received at least one dose of ELAHERE. In these 104 patients, the median age was 62 years (range: 35 to 85); 96% were White, 2% were Asian, and 2% did not have race reported. Two percent of patients were Hispanic or Latino. All patients had an ECOG PS of 0 (57%) or 1 (43%). Ten percent of patients had received 1 prior line of systemic therapy, 39% of patients had received 2 prior lines of systemic therapy, and 50% of patients had received 3 prior lines of systemic therapy. All patients had received prior bevacizumab and 47% had received a prior PARP inhibitor.
Efficacy results for Study 0417 are summarized in Table 7.
Table 10: Efficacy Results in Study 0417
|
ELAHERE
(N=104) |
Confirmed Overall Response Ratea
(95% CI) |
32%
(23, 42) |
| Complete response rate |
5% |
| Partial response rate |
27% |
| Duration of Response |
N=33 |
| Median duration of response, months (95% CI) |
6.9
(5.6, 9.7) |
| a Investigator assessment. |