Clinical Pharmacology for Avmapki Fakzynja Co-Pak
Mechanism Of Action
Avutometinib
Avutometinib is a MEK1 inhibitor. Avutometinib induces the formation of inactive RAF/MEK complexes and prevents phosphorylation of MEK1/2 by RAF. RAF and MEK proteins are regulators of the RAS/RAF/MEK/ERK (MAPK) pathway. Avutometinib inhibited MEK1/2 and ERK1/2 phosphorylation and proliferation of tumor cell lines harboring KRAS mutations. Treatment of cancer cells with avutometinib increased the level of phosphorylated focal adhesion kinase (FAK).
Defactinib
Defactinib is an inhibitor of FAK and proline-rich tyrosine kinase-2 (Pyk2), the two members of the FAK family of nonreceptor tyrosine kinases. Defactinib inhibited FAK autophosphorylation in cancer cells in vitro and in mouse xenograft models.
Avutometinib in combination with defactinib enhanced inhibition of cell proliferation in vitro and anti-tumor activity in mouse tumor models including LGSOC.
Pharmacodynamics
Avutometinib exposure-response relationships and the time course of pharmacodynamic response have not been fully characterized.
Defactinib exposure-response relationships and the time course of pharmacodynamic response have not been fully characterized.
Cardiac Electrophysiology
At the recommended doses for AVMAPKI FAKZYNJA CO-PACK, a mean increase in the QTc interval >20 msec was not observed. For the 88 patients with PR interval measured in RAMP-201, the mean PR interval increased by 16 msec from baseline to Cycle 1 Day 15 4-hours post dose.
Pharmacokinetics
The pharmacokinetics of avutometinib and defactinib were studied in healthy subjects and in patients with advanced solid tumors and are presented as mean (%CV) unless otherwise specified.
Avutometinib
Avutometinib exhibits dose proportional increases peak plasma concentrations (Cmax) and area under the concentration time curve (AUC) with a single dose ranging from 0.1 mg to 5 mg (0.03 to 1.6 times the approved recommended dose). No significant accumulation of avutometinib was observed at the recommended dosage.
Defactinib
Defactinib exhibits dose proportional increases in Cmax and AUC with twice daily dosing ranging from 12.5 mg to 450 mg (0.06 to 2.25 times the approved recommended dosage). Defactinib steady-state plasma concentrations are reached in approximately 15 days. Defactinib accumulation is approximately 1.5-fold at the approved recommended dosage.
Absorption
The median time to avutometinib peak plasma concentration (Tmax) under fasted conditions is approximately 2 hours.
The median time to defactinib Tmax under fed conditions is approximately 4 hours.
Effect of Food
No clinically significant differences in avutometinib AUC were observed following administration with a high-fat meal. Avutometinib Cmax was decreased by 29% following administration with a high-fat meal (approximately 900 to 1000 calories, 50% fat).
Defactinib AUC increased by 2.7-fold and Cmax increased by 1.9-fold following administration with a high-fat meal (approximately 900 to 1000 calories, 50% fat).
Distribution
Avutometinib steady state apparent volume of distribution (Vd) is 25 L (19%). Avutometinib human plasma protein binding is 99% in vitro.
Defactinib steady state apparent Vd is 1,560 L (59%). Defactinib human plasma protein binding is 90% in vitro.
Elimination
Avutometinib estimated elimination half-life is 51 hours (28%) and the apparent oral clearance (CL/F) is 0.3 L/h (30%).
Defactinib estimated elimination half-life is 9 hours (171%) and the CL/F is 69 L/h (173%).
Metabolism
Avutometinib is primarily metabolized by CYP3A4 and nonenzymatic degradation.
Defactinib is metabolized primarily by CYP3A4 and CYP2C9. Two major metabolites, N-desmethyl sulfonamide (M2) and N-desmethyl amide (M4), were identified in plasma. M2 and M4 AUCs represent 92% and 28% of defactinib exposure, respectively. M2 is inactive and M4 is equipotent when compared to defactinib.
Excretion
After a single dose of radiolabeled avutometinib 2.4 mg (0.8 times the approved recommended dose), 39% (9.5% unchanged) of the dose was recovered in feces and 52% (3.2% unchanged) in urine.
After a single dose of radiolabeled defactinib 400 mg (2 times the approved recommended dose), 87% (52% unchanged) of the dose was recovered in feces and 7.6% (0.8% unchanged) in urine.
Specific Populations
No clinically significant differences in the pharmacokinetics of avutometinib were observed based on age (21 to 87 years), sex, race (84% White, 3% Black and 2% Asian), body weight (40 to 169 kg), mild and moderate renal impairment (CLcr 30 to 89 mL/min, estimated by Cockcroft-Gault), or mild hepatic impairment (AST > ULN or total bilirubin >1 x ULN to 1.5 x ULN). The effect of severe renal impairment (CLcr < 30 mL/min) or moderate to severe hepatic impairment (AST or ALT ≥ 2.5 x ULN or total bilirubin ≥ 1.5 x ULN) on avutometinib pharmacokinetics is unknown.
No clinically meaningful differences in the pharmacokinetics of defactinib were observed based on age (21 to 87 years), sex, race (82% White, 3% Black and 2% Asian), body weight (40 to 169 kg), mild and moderate renal impairment (CLcr 30 to 89 mL/min), or mild hepatic impairment (AST > ULN or total bilirubin >1 x ULN to 1.5 x ULN). The effect of severe renal impairment (CLcr < 30 mL/min) or moderate to severe hepatic impairment (AST or ALT ≥ 2.5 x ULN or total bilirubin ≥ 1.5 x ULN) on defactinib pharmacokinetics is unknown.
Drug Interaction Studies
Clinical Studies
Strong CYP3A4 Inhibitors
No clinically significant differences in avutometinib pharmacokinetics were observed when used concomitantly with itraconazole (strong CYP3A4 inhibitor).
Defactinib Cmax increased by 2.2-fold and AUC by 3.9-fold following concomitant use with itraconazole (strong CYP3A4 inhibitor) 200 mg daily for 10 days. M4 AUC increased by 2.2-fold and Cmax decreased by 6.8%.
Strong CYP3A4 Inducers
Avutometinib AUC decreased by 34% with no clinically significant change in Cmax following coadministration with phenytoin (strong CYP3A4 inducer) three times daily for 23 days and a single dose of avutometinib 2.4 mg (0.8 times the approved recommended dose) on Day 17.
Defactinib Cmax decreased by 83% and AUC by 87% following coadministration with phenytoin (strong CYP3A4 inducer) three times daily for 23 days and a single dose of defactinib 200 mg (1.0 times the approved recommended dose) on Day 14. M4 AUC decreased by 79% and Cmax decreased by 70%.
Proton Pump Inhibitors (PPIs)
Defactinib displayed pH-dependent aqueous solubility [see DESCRIPTION]. Defactinib AUC decreased by 79% and Cmax decreased by 85% following concomitant use of multiple doses of omeprazole (PPI) 40 mg daily. M4 AUC decreased by 83% and Cmax decreased by 88%.
In Vitro Studies
CYP450 Enzymes
Avutometinib is a CYP3A4 substrate, but not a substrate of CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, and CYP2D6. Avutometinib is not an inhibitor of CYP3A4, CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, and CYP2D6. Avutometinib is not an inducer of CYP3A4, CYP2B6, and CYP1A2.
Defactinib is a CYP3A4 and CYP2C9 substrate, but not a substrate of CYP1A2, CYP2B6, CYP2C8, CYP2C19, and CYP2D6. Defactinib is a reversible inhibitor of CYP3A4 and CYP2C9, but not CYP1A2, CYP2B6, CYP2C8, CYP2C19, and CYP2D6. Defactinib is a time-dependent inhibitor of CYP3A4. Defactinib is an inducer of CYP2B6, and CYP1A2, but not CYP3A4.
UGT Enzymes
Defactinib may inhibit UGT1A1 at clinically relevant concentrations.
Transporter Systems
Avutometinib is a substrate of P-gp and BCRP, but not a substrate of MATE1, MATE2-K, OAT1, OAT3, OATP1B1, OATP1B3, OCT1 and OCT2. Avutometinib is not an inhibitor of P-gp, BCRP, MATE1, MATE2-K, OAT1, OAT3, OATP1B1, OATP1B3, OCT1 and OCT2.
Defactinib is a BCRP and P-gp substrate, but not a substrate of MATE1, MATE2-K, OAT1, OAT3, OATP1B1, OATP1B3, OCT1, and OCT2. Defactinib is an inhibitor of P-gp, BCRP, OATP1B1, OATP1B3, and MATE2-K, but not an inhibitor of MATE1, OAT1, OAT3, OCT1, and OCT2.
Animal Toxicology And/Or Pharmacology
Avutometinib
In repeat-dose toxicity studies up to 13-weeks duration in rats and monkeys, tissue mineralization in multiple organs was observed at doses ≥ 0.01 mg/kg/day and 0.03 mg/kg/day, respectively (≥ 0.06 and 1.4 times the human exposure at the recommended dose based on AUC, respectively) as well as increased inorganic phosphorus in rats.
In a cardiovascular telemetry study in monkeys, a single oral dose of avutometinib increased systolic, diastolic, and mean blood pressure at 1 mg/kg (approximately 15 times the human Cmax at the recommended dose). In the repeat-dose toxicology studies up to 13-weeks duration in rats, myocardial degeneration and necrosis were observed at doses ≥ 0.01 mg/kg/day (below the human exposure at the recommended dose based on AUC).
Defactinib
In a cardiovascular telemetry study in dogs, a single oral dose of defactinib decreased myocardial contractility at doses ≥ 5 mg/kg (approximately the human exposure at the recommended dose based on AUC) and increased ventricular systolic, diastolic and mean blood pressure at doses ≥ 25 mg/kg/day (≥ 2.7 times the human exposure at the recommended dose based on AUC). In the 13-week repeat-dose toxicology study in dogs, myocardium hypertrophy was observed at doses ≥ 1 mg/kg/day (below the human exposure at the recommended dose based on AUC) at the end of the dosing and recovery periods.
Clinical Studies
The efficacy of AVMAPKI FAKZYNJA CO-PACK was evaluated in RAMP-201 (NCT04625270), an open-label, multicenter study that included 57 adult patients with measurable KRAS-mutated recurrent LGSOC. Patients were required to have received at least one prior systemic therapy, including a platinum-based regimen. KRAS mutation status was determined by prospective local testing using next generation sequencing (NGS) or polymerase chain reaction of tumor tissue specimens. Patients were excluded if they were candidates for debulking surgery, were on treatment with warfarin, had an active skin disorder requiring systemic therapy within the past year, or had an ocular disorder (including a history of retinal pathology, an active or chronic visually significant corneal disorder, or a history of glaucoma).
Patients received AVMAPKI 3.2 mg orally twice weekly for the first 3 weeks out of a 4-week cycle and FAKZYNJA 200 mg orally twice daily for the first 3 weeks out of a 4-week cycle until disease progression or unacceptable toxicity. The major efficacy outcome measure was overall response rate (ORR) assessed by blinded independent review committee (BIRC) according to Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1. An additional efficacy outcome measure was duration of response (DoR). Tumor response assessments occurred every 8 weeks for the first 72 weeks and every 12 weeks thereafter.
The median age was 60 years (range: 29 to 87); 75% were White, 3.5% were Asian, 3.5% were Black or African American, and 18% did not have race reported; 3.5% of patients were Hispanic or Latino; 72% had an ECOG PS of 0 and 28% had ECOG PS of 1. The KRAS mutations identified by local testing were G12V (53%), G12D (35%), Q61H (3.5%), G12C (1.8%), G12R (1.8%), A146V (1.8%), and mutations not otherwise specified at G12x (1.8%) and on codon 12/13 (1.8%). Fourteen percent of patients had received 1 prior line of systemic therapy, 25% of patients had received 2 prior lines, 18% had received 3 prior lines and 40% had received more than 3 prior lines of systemic therapy. All patients had received prior platinum-based chemotherapy, 84% received prior hormonal therapy (as maintenance or treatment), 40% received prior bevacizumab and 21% received a prior MEK inhibitor.
Efficacy results are presented in Table 5.
Table 5 Efficacy Results in RAMP-201
|
AVMAPKI FAKZYNJA CO-PACK
N = 57 |
| Confirmed Overall Response Rate (95% CI)1 |
44%
(31,58) |
| Complete response |
3.5% |
| Partial response |
40% |
| Duration of Response (DoR) |
| Range (months) |
3.3, 31.1 |
| 1 ORR 95% CI calculated using Clopper-Pearson method |
The tumor KRAS mutations observed in the 25 responders were A146V, G12D, G12R, G12V, and Q61H.