Abemaciclib

Abemaciclib and its major active metabolites inhibit the renal transporters organic cation transporter 2 (OCT2), multidrug and extrusion toxin protein (MATE1), and MATE2-K. In vivo interactions of abemaciclib with clinically relevant substrates of these transporters, such as dofetilide or creatinine, may occur (see section 4.8). In a clinical drug interaction study with metformin (substrate of OCT2, MATE1 and 2) co-administered with 400 mg abemaciclib, a small but not clinically relevant increase (37%) in metformin plasma exposure was observed. This was found to be due to reduced renal secretion with unaffected glomerular filtration.

Abemaciclib is primarily metabolised by CYP3A4.

Co-administration of abemaciclib with CYP3A4 inhibitors can increase plasma concentrations of abemaciclib. In patients with advanced and/or metastatic cancer, co-administration of the CYP3A4 inhibitor clarithromycin resulted in a 3.4-fold increase in the plasma exposure of abemaciclib and a 2.5-fold increase in the combined unbound potency adjusted plasma exposure of abemaciclib and its active metabolites.

Use of strong CYP3A4 inhibitors together with abemaciclib should be avoided. If strong CYP3A4 inhibitors need to be co-administered, the dose of abemaciclib should be reduced, followed by careful monitoring of toxicity. Examples of strong CYP3A4 inhibitors include, but not limited to: clarithromycin, itraconazole, ketoconazole, lopinavir/ritonavir, posaconazole or voriconazole. Avoid grapefruit or grapefruit juice.

No dose adjustment is necessary for patients treated with moderate or weak CYP3A4 inhibitors. There should, however, be close monitoring for signs of toxicity.

No dose adjustments are necessary in patients with mild or moderate renal impairment. There are no data regarding abemaciclib administration in patients with severe renal impairment, end stage renal disease, or in patients on dialysis. Abemaciclib should be administered with caution in patients with severe renal impairment, with close monitoring for signs of toxicity.

In healthy subjects, co-administration of abemaciclib and the P-glycoprotein (P-gp) substrate loperamide resulted in an increase in loperamide plasma exposure of 9% based on AUC_0-∞ and 35% based on C_max. This was not considered to be clinically relevant. However, based on the in vitro inhibition of P-gp and breast cancer resistance protein (BCRP) observed with abemaciclib, in vivo interactions of abemaciclib with narrow therapeutic index substrates of these transporters, such as digoxin or dabigatran etexilate, may occur.

Co-administration of abemaciclib with the strong CYP3A4 inducer rifampicin decreased the plasma concentration of abemaciclib by 95% and unbound potency adjusted plasma concentration of abemaciclib plus its active metabolites by 77% based on AUC_0-∞. Concomitant use of strong CYP3A4 inducers (including, but not limited to: carbamazepine, phenytoin, rifampicin and St. John’s wort) should be avoided due to the risk of decreased efficacy of abemaciclib.

In patients with severe (Child Pugh C) hepatic impairment, a decrease in dosing frequency to once daily is recommended.

The effect of abemaciclib on fertility in humans is unknown. In animal studies, no effects on female reproductive organs were observed. However, cytotoxic effects to the male reproductive tract in rats and dogs indicate that abemaciclib may impair fertility in males.

Venous thromboembolic events were reported in 5.3% of patients treated with abemaciclib plus fulvestrant or aromatase inhibitors, compared to 0.8% of patients treated with placebo plus fulvestrant or aromatase inhibitors. Patients should be monitored for signs and symptoms of deep vein thrombosis and pulmonary embolism and treated as medically appropriate.

Increases in ALT and AST were reported in patients receiving abemaciclib. Based on the level of ALT or AST elevation, abemaciclib may require dose modification.

Management recommendations for increased aminotransferases:

Alanine aminotransferase (ALT) and aspartate aminostransferase (AST) should be monitored prior to the start of Verzenios therapy, every two weeks for the first two months, monthly for the next two months, and as clinically indicated.

Dose adjustment recommendations for adverse reactions:

^a NCI CTCAE
ULN = upper limit of normal

Interstitial lung disease (ILD)/pneumonitis was reported in patients receiving abemaciclib. Monitor patients for pulmonary symptoms indicative of ILD/pneumonitis and treat as medically appropriate. Based on the grade of ILD/pneumonitis, abemaciclib may require dose modification. Permanently discontinue abemaciclib in patients with Grade 3 or 4 ILD/pneumonitis.

Management recommendations for interstitial lung disease (ILD)/pneumonitis:

Dose adjustment recommendations for adverse reactions:

^a NCI CTCAE

Infections were reported in patients receiving abemaciclib plus endocrine therapy at a higher rate than in patients treated with placebo plus endocrine therapy. Lung infection was reported in patients receiving abemaciclib without concurrent neutropenia. Fatal events occurred in <1% of patients. Patients should be monitored for signs and symptoms of infection and treated as medically appropriate.

Diarrhoea is the most common adverse reaction. Across clinical studies, median time to onset of the first diarrhoea event was approximately 6 to 8 days, and median duration of diarrhoea was 9 to 12 days (Grade 2) and 6 to 8 days (Grade 3). Diarrhoea can be associated with dehydration. Patients should start treatment with antidiarrhoeal agents such as loperamide at the first sign of loose stools, increase oral fluids and notify their healthcare provider. Dose modification is recommended for patients who develop ≥ Grade 2 diarrhoea.

Management recommendations for diarrhoea:

Treatment with antidiarrhoeal agents, such as loperamide, should be started at the first sign of loose stools.

Dose adjustment recommendations for adverse reactions:

^a NCI CTCAE

Neutropenia was reported in patients receiving abemaciclib. Dose modification is recommended for patients who develop Grade 3 or 4 neutropenia. Fatal events occurred in <1% of patients. Patients should be instructed to report any episode of fever to their healthcare provider.

Table 2. Management recommendations for haematologic toxicities:

Complete blood counts should be monitored prior to the start of abemaciclib therapy, every two weeks for the first two months, monthly for the next two months, and as clinically indicated. Before treatment initiation, absolute neutrophil counts (ANC) ≥1500/mm³, platelets ≥100,000/mm³, and haemoglobin ≥8 g/dL are recommended.

Table 1. Dose adjustment recommendations for adverse reactions:

^a NCI Common Terminology Criteria for Adverse Events (CTCAE)
^b ANC: Grade 1: ANC < LLN – 1500/mm³; Grade 2: ANC 1000 - <1500/mm³; Grade 3: ANC 500 - <1000/mm³; Grade 4: ANC <500/mm³
LLN = lower limit of normal

There are no data from the use of abemaciclib in pregnant women. Studies in animals have shown reproductive toxicity. Abemaciclib is not recommended during pregnancy and in women of child-bearing potential not using contraception.

It is unknown whether abemaciclib is excreted in human milk. A risk to newborns/infants cannot be excluded. Patients receiving abemaciclib should not breast-feed.

Women of childbearing potential / Contraception in females

Women of childbearing potential should use highly effective contraception methods (e.g. double-barrier contraception) during treatment and for at least 3 weeks after completing therapy.

Fertility

The effect of abemaciclib on fertility in humans is unknown. In animal studies, no effects on female reproductive organs were observed. However, cytotoxic effects to the male reproductive tract in rats and dogs indicate that abemaciclib may impair fertility in males.

Abemaciclib has minor influence on the ability to drive and use machines. Patients should be advised to be cautious when driving or using machines in case they experience fatigue or dizziness during treatment with abemaciclib.

Summary of the safety profile

The most commonly occurring adverse reactions are diarrhoea, infections, neutropenia, anaemia, fatigue, nausea, vomiting and decreased appetite.

List of adverse reactions

In the following list, adverse reactions are listed in order of MedDRA body system organ class and frequency. Frequency gradings are: very common (≥1/10), common (≥1/100 to <1/10), uncommon (≥1/1,000 to <1/100), rare (≥1/10,000 to <1/1,000), very rare (<1/10,000), and not known (cannot be estimated from the available data). Within each frequency grouping, adverse reactions are presented in order of decreasing seriousness.

Adverse reactions reported in phase 3 studies of abemaciclib in combination with endocrine therapy (N=768):

^a Abemaciclib in combination with letrozole, anastrozole, or fulvestrant.
^b Infections includes all PTs that are part of the System Organ Class Infections and infestations.
^c Venous thromboembolic events include DVT, pulmonary embolism, cerebral venous sinus thrombosis, subclavian, axillary vein thrombosis,DVT inferior vena cava and pelvic venous thrombosis.

Description of selected adverse reactions

Neutropenia

Neutropenia was reported frequently (45.1%). and a Grade 3 or 4 decrease in neutrophil counts (based on laboratory findings) was reported in 28.2% of patients receiving abemaciclib in combination with aromatase inhibitors or fulvestrant. The median time to onset of Grade 3 or 4 neutropenia was 29 to 33 days, and median time to resolution was 11 to 15 days. Febrile neutropenia was reported in 0.9% patients. Dose modification is recommended for patients who develop Grade 3 or 4 neutropenia.

Diarrhoea

Diarrhoea was the most commonly reported adverse reaction. Incidence was greatest during the first month of abemaciclib treatment and was lower subsequently. The median time to onset of the first diarrhoea event was approximately 6 to 8 days across studies, and the median duration of diarrhoea was 9 to 12 days (Grade 2) and 6 to 8 days (Grade 3) across studies. Diarrhoea returned to baseline or lesser grade with supportive treatment such as loperamide and/or dose adjustment.

Increased aminotransferases

In patients receiving abemaciclib in combination with aromatase inhibitors or fulvestrant, ALT and AST elevations were reported frequently (15.1% and 14.2%, respectively). Grade 3 or 4 ALT or AST elevations (based on laboratory findings) were reported in 6.1% and 4.2% patients. The median time to onset of Grade 3 or 4 ALT elevation was 57 to 61 days, and median time to resolution was 14 days. The median time to onset of Grade 3 or 4 AST elevation was 71 to 185 days, and median time to resolution was 13 to 15 days. Dose modification is recommended for patients who develop Grade 3 or 4 ALT or AST increase.

Creatinine

Although not an adverse reaction, abemaciclib has been shown to increase serum creatinine in 98.3% of patients (based on laboratory findings), 1.9% Grade 3 or 4 (based on laboratory findings). In patients receiving an aromatase inhibitor or fulvestrant alone, 78.4% reported an increase in serum creatinine (all laboratory grades). Abemaciclib has been shown to increase serum creatinine due to inhibition of renal tubular secretion transporters without affecting glomerular function (as measured by iohexol clearance). In clinical studies, increases in serum creatinine occurred within the first month of abemaciclib dosing, remained elevated but stable through the treatment period, were reversible upon treatment discontinuation, and were not accompanied by changes in markers of renal function, such as blood urea nitrogen (BUN), cystatin C, or calculated glomerular filtration rate based on cystatin C.