VERZENIOS Film-coated tablet Ref.[7607] Active ingredients: Abemaciclib

Pharmacotherapeutic group: Antineoplastic agents, protein kinases inhibitors
ATC code: L01XE50

Mechanism of action

Abemaciclib is a potent and selective inhibitor of cyclin-dependent kinases 4 and 6 (CDK4 and CDK6), and most active against Cyclin D1/CDK4 in enzymatic assays. Abemaciclib prevents retinoblastoma protein (Rb) phosphorylation, blocking cell cycle progression from the G1 to the S-phase of cell division, leading to suppression of tumour growth. In oestrogen receptor-positive breast cancer cell lines, sustained target inhibition with abemaciclib prevented rebound of Rb phosphorylation resulting in cell senescence and apoptosis. In vitro, Rb-negative and Rb-depleted cancer cell lines are generally less sensitive to abemaciclib. In breast cancer xenograft models, abemaciclib dosed daily without interruption at clinically relevant concentrations alone or in combination with anti-oestrogens resulted in reduction of tumour size.

Pharmacodynamic effects

In cancer patients, abemaciclib inhibits CDK4 and CDK6 as indicated by inhibition of phosphorylation of Rb and topoisomerase II alpha, which results in cell cycle inhibition upstream of the G1 restriction point.

Cardiac electrophysiology

The effect of abemaciclib on the QTcF interval was evaluated in 144 patients with advanced cancer. No large change (that is, >20 ms) in the QTcF interval was detected at the mean observed maximal steady state abemaciclib concentration following a therapeutic dosing schedule. In an exposure-response analysis in healthy subjects at exposures comparable to a 200 mg twice-daily dose, abemaciclib did not prolong the QTcF interval to any clinically relevant extent.

Clinical efficacy and safety

Randomised Phase 3 Study MONARCH 3: Verzenios in combination with aromatase inhibitors

The efficacy and safety of Verzenios in combination with an aromatase inhibitor (anastrozole or letrozole) was evaluated in MONARCH 3, a randomised, double-blind, placebo-controlled phase 3 study in women with HR positive, HER2 negative locally advanced or metastatic breast cancer who had not received prior systemic therapy in this disease setting. Patients were randomised in a 2:1 ratio to receive Verzenios 150 mg twice daily plus a non-steroidal aromatase inhibitor given daily at the recommended dose versus placebo plus a non-steroidal aromatase inhibitor according to the same schedule. The primary endpoint was investigator-assessed progression-free survival (PFS) evaluated according to RECIST 1.1; key secondary efficacy endpoints included objective response rate (ORR), clinical benefit rate (CBR) and overall survival (OS).

The median age of patients enrolled was 63 years (range 32-88). Approximately 39% of patients had received chemotherapy and 44% had received antihormonal therapy in the (neo)adjuvant setting. Patients with prior (neo)adjuvant endocrine therapy must have completed this therapy at least 12 months before study randomisation. The majority of patients (96%) had metastatic disease at baseline. Approximately 22% of patients had bone-only disease, and 53% patients had visceral metastases.

The study met its primary endpoint of improving PFS. Primary efficacy results are summarised in Table 8 and Figure 1.

Table 8. MONARCH 3: Summary of efficacy data (Investigator assessment, intent-to-treat population):

^a Measurable disease defined per RECIST version 1.1
^b Complete response + partial response
^c Complete response + partial response + stable disease for ≥ 6 months
N=number of patients; CI=confidence interval; NR=not reached.

Figure 1. MONARCH 3: Kaplan-Meier plot of progression-free survival (Investigator assessment, intent-to-treat population):

Progression-free survival (PFS) was significantly prolonged in the Verzenios plus aromatase inhibitor (AI) arm, (Hazard Ratio [HR] of 0.540 [95% CI, 0.418 to 0.698]); median PFS was 28.18 months in the Verzenios plus AI arm and was 14.76 months in the placebo plus AI arm. These results correspond to a clinically meaningful reduction in the risk of disease progression or death of 46% for patients treated with abemaciclib plus an aromatase inhibitor.

Overall survival was not mature at the final PFS analysis (93 events observed across the two arms). The HR was 1.057 (95% CI: 0.683, 1.633), p=0.8017.

A series of prespecified subgroup PFS analyses showed consistent results across patient subgroups including age (<65 or ≥65 years), disease site, disease setting (de novo metastatic vs recurrent metastatic vs locally advanced recurrent), presence of measurable disease, progesterone receptor status, and baseline ECOG performance status. A reduction in the risk of disease progression or death was observed in patients with visceral disease, (HR of 0.567 [95% CI: 0.407, 0.789]), median PFS 21.6 months versus 14.0 months; in patients with bone-only disease (HR 0.565, [95% CI: 0.306, 1.044]); and in patients with measurable disease (HR 0.517, [95% CI: 0.392, 0.681]).

Randomised Phase 3 Study MONARCH 2: Verzenios in combination with fulvestrant

The efficacy and safety of Verzenios in combination with fulvestrant was evaluated in MONARCH 2, a randomised, double-blind, placebo-controlled phase 3 study in women with HR positive, HER2 negative locally advanced or metastatic breast cancer. Patients were randomised in a 2:1 ratio to receive Verzenios 150 mg twice daily plus fulvestrant 500 mg at intervals of one month, with an additional 500 mg dose given two weeks after the initial dose, versus placebo plus fulvestrant according to the same schedule. The primary endpoint was investigator-assessed PFS evaluated according to RECIST 1.1; key secondary efficacy endpoints included objective response rate (ORR), clinical benefit rate (CBR) and overall survival (OS).

The median age of patients enrolled was 60 years (range, 32-91 years). In each treatment arm the majority of patients were white, and had not received chemotherapy for metastatic disease. 17% of patients were pre/perimenopausal on ovarian suppression with a GnRH agonist. Approximately 56% patients had visceral metastases. Approximately 25% of patients had primary endocrine resistance (progression on endocrine therapy within the first 2 years of adjuvant endocrine therapy or within the first 6 months of first line endocrine therapy for metastatic breast cancer) and for the majority, endocrine resistance developed later. 59% of patients had most recent endocrine therapy in the (neo)adjuvant setting, and 38% in metastatic setting.

The study met its primary endpoint of improving PFS. Primary efficacy results are summarised in Table 9 and Figure 2.

Table 9. MONARCH 2: Summary of efficacy data (Investigator assessment, intent-to-treat population):

^a Measurable disease defined per RECIST version 1.1
^b Complete response + partial response
^c Complete response + partial response + stable disease for ≥6 months
N=number of patients; CI=confidence interval; NR=not reached.

Figure 2. MONARCH 2: Kaplan-Meier plot of progression-free survival (Investigator assessment, intent-to-treat population):

Median PFS was significantly prolonged in the Verzenios plus fulvestrant arm (HR of 0.553 [95% CI 0.449, 0.681]); median PFS was 16.4 months versus 9.3 months in the placebo plus fulvestrant arm. These results correspond to a clinically meaningful reduction in the risk of disease progression or death of 44.7% and a 7.2 month improvement in median PFS for patients treated with Verzenios plus fulvestrant. Verzenios plus fulvestrant prolonged progression-free survival with neither a clinically meaningful or significant detriment to health-related quality of life.

A series of prespecified subgroup PFS analyses showed consistent results across patient subgroups including age (<65 or ≥65 years), race, geographic region, disease site, endocrine therapy resistance, presence of measurable disease, progesterone receptor status, and menopausal status. A reduction in the risk of disease progression or death was observed in patients with visceral disease, (HR of 0.481 [95% CI: 0.369, 0.627]), median PFS 14.7 months versus 6.5 months; in patients with bone-only disease (HR of 0.543 [95% CI: 0.355, 0.833]); patients with measurable disease (HR of 0.523 [95% CI: 0.412, 0.644]). In patients who were pre/perimenopausal, the hazard ratio was 0.415 (95% CI: 0.246, 0.698); in patients who were progesterone receptor negative, the HR was 0.509 (95% CI: 0.325, 0.797).

In a sub-population with locally advanced or metastatic disease that had not received prior endocrine therapy, the PFS was also consistent.

Overall survival (OS) analysis in the ITT population showed a statistically significant improvement in patients receiving Verzenios plus fulvestrant compared with those receiving placebo plus fulvestrant. The overall survival results are summarized in Table 10 and Figure 3.

Table 10. MONARCH 2: Summary of overall survival data (Intent-to-treat population):

N = number of patients; CI = confidence interval; OS = overall survival

Figure 3. MONARCH 2: Kaplan-Meier plot of overall survival (Intent-to-treat population):

Analyses for OS by stratification factors showed OS HR of 0.675 (95% CI: 0.511, 0.891) in patients with visceral disease, and 0.686 (95% CI: 0.451, 1.043) in patients with primary endocrine resistance.

Paediatric population

The European Medicines Agency has waived the obligation to submit the results of studies with Verzenios in all subsets of the paediatric population in breast cancer (see section 4.2 for information on paediatric use).