Clinical Pharmacology for Cresemba
Mechanism Of Action
Isavuconazonium sulfate is the prodrug of isavuconazole, an azole antifungal [see Microbiology].
Pharmacodynamics
Pharmacokinetic/Pharmacodynamic Relationship
In patients treated with CRESEMBA for invasive aspergillosis in a controlled trial, there was no significant association between plasma AUC or plasma isavuconazole concentration and efficacy.
Cardiac Electrophysiology
The effect on QTc interval of multiple doses of CRESEMBA capsules was evaluated. CRESEMBA was administered as 2 capsules (equivalent to 200 mg isavuconazole) three times daily on days 1 and 2 followed by either 2 capsules or 6 capsules (equivalent to 600 mg isavuconazole) once daily for 13 days in a randomized, placebo- and activecontrolled (moxifloxacin 400 mg single-dose), four-treatment-arm, parallel study in 160 healthy subjects.
Isavuconazole resulted in dose-related shortening of the QTc interval. For the 2-capsule dosing regimen, the least squares mean (LSM) difference from placebo was -13.1 msec at 2 hours postdose [90% CI: -17.1, -9.1 msec]. Increasing the dose to 6 capsules resulted in an LSM difference from placebo of -24.6 msec at 2 hours postdose [90% CI: -28.7, -20.4]. CRESEMBA was not evaluated in combination with other drugs that reduce the QTc interval, so the additive effects are not known.
Pharmacokinetics
General Pharmacokinetics
In healthy subjects, the pharmacokinetics of isavuconazole following oral administration of CRESEMBA capsules at isavuconazole equivalent doses up to 600 mg per day (6 capsules) are dose proportional (Table 6). Based on a population pharmacokinetics analysis of healthy subjects and patients, the mean plasma half-life of isavuconazole was 130 hours and the mean volume of distribution (Vss) was approximately 450 L following intravenous administration.
Table 6. Steady State Pharmacokinetic Parameters of Isavuconazole Following Administration of 186 mg CRESEMBA Capsules
| Parameter |
CRESEMBA 186 mg
2 Capsules1
(n = 37) |
CRESEMBA 186 mg
6 Capsules1
(n = 32) |
| Cmax (mg/L) |
| Mean |
7.5 |
20.0 |
| SD |
1.9 |
3.6 |
| CV % |
25.2 |
17.9 |
| tmax (hr) |
| Median |
3.0 |
4.0 |
| Range |
2.0 – 4.0 |
2.0 – 4.0 |
| AUC (mg•hr/L) |
| Mean |
121.4 |
352.8 |
| SD |
35.8 |
72.0 |
| CV % |
29.5 |
20.4 |
| 1. Each capsule contains the equivalent of 100 mg of isavuconazole |
Following oral administration of CRESEMBA capsules at an isavuconazole equivalent dose of 200 mg in 66 fasted healthy male subjects, a single dose administration of two 186 mg CRESEMBA capsules and five 74.5 mg CRESEMBA capsules exhibited a mean (SD) Cmax and AUC of 3.3 (0.6) mg/L and 112.2 (30.3) mg·hr/L, respectively, and 3.3 (0.6) mg/L and 118.0 (33.1) mg·hr/L, respectively.
Absorption
After oral administration of CRESEMBA in healthy volunteers, the active moiety, isavuconazole, generally reaches maximum plasma concentrations (Cmax) 2 hours to 3 hours after single and multiple dosing. The absolute bioavailability of isavuconazole following oral administration of CRESEMBA is 98%. No significant concentrations of the prodrug or inactive cleavage product were seen in plasma after oral administration.
Following intravenous administration of CRESEMBA, maximal plasma concentrations of the prodrug and inactive cleavage product were detectable during infusion and declined rapidly following the end of administration. The prodrug was below the level of detection by 1.25 hours after the start of a one-hour infusion. The total exposure of the prodrug based on AUC was less than 1% that of isavuconazole. The inactive cleavage product was quantifiable in some subjects up to 8 hours after the start of infusion. The total exposure of inactive cleavage product based on AUC was approximately 1.3% that of isavuconazole.
CRESEMBA given orally as an intravenous solution administered via nasogastric (NG) tube provides systemic isavuconazole exposure that is similar to the oral capsule (Table 7).
Table 7. Statistical Comparison of Plasma Pharmacokinetics of Isavuconazole Following Single Oral Dose Administration of 2 Capsules of 186 mg (Equivalent to 200 mg Isavuconazole) and Single Intravenous Solution Dose Administration of 372 mg (Equivalent to 200 mg Isavuconazole) via Nasogastric (NG) Tube in Healthy Adult Subjects Under Fasted Conditions
|
CRESEMBA IV Solution via NG
Tube |
CRESEMBA Oral Capsules |
NG Tube/ Oral Capsule |
Pharmacokinetic
Parameter |
N |
Mean (%CV) |
N |
Mean (%CV) |
GMR (90% CI) |
| Cmax (mg/L) |
13 |
2.3 (23.6) |
13 |
2.2 (26.7) |
105.34
(89-124) |
AUC0-72hr
(mg·hr/L) |
13 |
34.9 (22.1) |
13 |
35.8 (24.6) |
97.81
(93-103) |
AUC0-∞
(mg·hr/L) |
12 |
98.1 (44.5) |
12 |
100.1 (46.8) |
99.27
(93-106) |
| GMR = Geometric least-squares mean ratio; CI = confidence interval |
Effect of Food
Coadministration of CRESEMBA equivalent to isavuconazole 400 mg oral dose with a high-fat meal reduced isavuconazole Cmax by 9% and increased AUC by 9%. CRESEMBA can be taken with or without food.
Distribution
Isavuconazole is extensively distributed with a mean steady state volume of distribution (Vss) of approximately 450 L. Isavuconazole is highly protein bound (greater than 99%), predominantly to albumin.
Elimination
Metabolism
In in vitro studies isavuconazonium sulfate is rapidly hydrolyzed in blood to isavuconazole by esterases, predominantly by butylcholinesterase. Isavuconazole is a substrate of cytochrome P450 enzymes 3A4 and 3A5.
Following single doses of [cyano 14C] isavuconazonium and [pyridinylmethyl 14C] isavuconazonium in humans, in addition to the active moiety (isavuconazole) and the inactive cleavage product, a number of minor metabolites were identified. Except for the active moiety isavuconazole, no individual metabolite was observed with an AUC greater than 10% of drug-related material.
In vivo studies indicate that CYP3A4, CYP3A5 and subsequently uridine diphosphate-glucuronosyltransferases (UGT) are involved in the metabolism of isavuconazole.
Excretion
Following oral administration of radio-labeled isavuconazonium sulfate to healthy volunteers, a mean of 46.1% of the total radioactive dose was recovered in the feces and 45.5% was recovered in the urine.
Renal excretion of isavuconazole itself was less than 1% of the dose administered.
The inactive cleavage product is primarily eliminated by metabolism and subsequent renal excretion of the metabolites. Renal elimination of intact cleavage product was less than 1% of the total dose administered. Following intravenous administration of radio-labeled cleavage product, 95% of the total radioactive dose was excreted in the urine.
Special populations
Geriatric Patients
The AUC of isavuconazole following a single oral dose of CRESEMBA equivalent to 200 mg isavuconazole in elderly subjects (65 years and older) was similar to that in younger volunteers (18 years to 45 years). The AUC was similar between younger female and male subjects and between elderly and younger males.
Elderly female AUC estimates were 38% and 47% greater than AUC estimates obtained in elderly males and younger females, respectively. The pharmacokinetic difference in elderly females receiving CRESEMBA are not considered to be clinically significant. Therefore, no dose adjustment is required based on age and gender.
Pediatric Patients
The pharmacokinetics of isavuconazole were evaluated in two clinical studies (N = 73) in pediatric patients aged 1 to less than 18 years of age which included twenty-eight patients with at least possible invasive aspergillosis or possible invasive mucormycosis.
Table 8. Derived Steady State Isavuconazole AUC (mg•hr/L) values in Pediatric Patients, by Age Group
| Dosage |
15 mg/kg1 |
10 mg/kg2 |
10 mg/kg
or
Maximum Dose of 372 mg3 |
| Age Group |
1 to < 3 years
(n=5) |
3 to < 6 years
(n=10) |
6 to < 12 years
(n=29) |
12 to < 18 years
(n=29) |
| Mean |
80.2 |
103.3 |
97.3 |
104.2 |
| Median |
64.3 |
110.3 |
87.7 |
97.7 |
| Minimum - Maximum |
53.7 - 155 |
51.5 – 159.1 |
37.8– 153.8 |
35.5 – 215.6 |
1. Estimated AUCss values of 15 mg/kg that were derived from existing values of pediatric patients that received 10 mg/kg of CRESEMBA for injection administered intravenously.
2. CRESEMBA for injection administered intravenously.
3. CRESEMBA for injection administered intravenously or CRESEMBA capsules administered orally. |
Race
A 2-compartment population pharmacokinetic model was developed to assess the pharmacokinetics of isavuconazole between healthy Western and Chinese subjects. Chinese subjects were found to have on average a 40% lower clearance compared to Western subjects (1.6 L/hr for Chinese subjects as compared to 2.6 L/hr for Western subjects) and therefore approximately 50% higher AUC than Western subjects. Body mass index (BMI) did not play a role in the observed differences. No dose adjustment is recommended for Chinese patients.
Gender
AUC estimates were similar between young female and male subjects (18 years to 45 years). There was a difference in AUC for elderly females (see Geriatric section above). No dose adjustment is required based on gender.
Patients With Renal Impairment
Total isavuconazole AUC and Cmax were not affected to a clinically meaningful extent in subjects with mild, moderate and severe renal impairment relative to healthy controls. No dose adjustment is necessary in patients with renal impairment.
Isavuconazole is not readily dialyzable. A dose adjustment is not warranted in patients with ESRD.
Patients With Hepatic Impairment
After a single-dose of CRESEMBA equivalent to 100 mg of isavuconazole was administered to 32 patients with mild (Child-Pugh Class A) hepatic impairment and 32 patients with moderate (Child-Pugh Class B) hepatic impairment (16 intravenous and 16 oral patients per Child-Pugh Class), the least squares mean systemic exposure (AUC) increased 64% and 84% in the Child-Pugh Class A group and the Child-Pugh Class B group, respectively, relative to 32 age and weight-matched healthy subjects with normal hepatic function. Mean Cmax was 2% lower in the Child-Pugh Class A group and 30% lower in the Child-Pugh Class B group. The population pharmacokinetic evaluation of isavuconazole in healthy subjects and patients with mild and moderate hepatic impairment demonstrated that the mild and moderate hepatic impairment population had 40% and 48% lower isavuconazole clearance (CL) values, respectively, compared to the healthy population. It is recommended that the standard CRESEMBA loading dose and maintenance dose regimen be utilized in patients with mild to moderate hepatic disease. CRESEMBA has not been studied in patients with severe hepatic impairment (Child-Pugh Class C).
Drug Interaction Studies
In Vitro Studies
CYP450 Enzymes
Isavuconazole is a substrate of CYP3A4 and CYP3A5. Isavuconazole is an inhibitor of CYP3A4, CYP2C8, CYP2C9, CYP2C19, and CYP2D6. Isavuconazole is an inducer of CYP3A4, CYP2B6, CYP2C8, and CYP2C9.
Transporter Systems
Isavuconazole is an inhibitor of P-gp-, BCRP- and OCT2.
Clinical Studies And Model-Informed Approaches
The effect of coadministration of drugs on the pharmacokinetics of isavuconazole and the effect of isavuconazole on the pharmacokinetics of coadministered drugs were studied after single and multiple doses of isavuconazole in healthy subjects.
The effects of ketoconazole, rifampin, lopinavir/ritonavir, and esomeprazole on isavuconazole are shown in Figure 1.
Ketoconazole
As a strong CYP3A4 inhibitor, ketoconazole increased the isavuconazole Cmax by 9% and isavuconazole AUC by 422% after multiple-dose administration of ketoconazole (200 mg twice daily) for 24 days and a single-dose of CRESEMBA equivalent to 200 mg of isavuconazole. Isavuconazole is a sensitive CYP3A4 substrate and use with strong CYP3A4 inhibitors are contraindicated per Section 4 and Figure 1.
Lopinavir/Ritonavir
Lopinavir/ritonavir (400 mg/100 mg twice daily) increased the Cmax and AUC of isavuconazole by 74% and 96%, respectively, with concurrent decreases in the mean AUCs of lopinavir and ritonavir by 27% and 31%, respectively.
Rifampin
Rifampin (600 mg) decreased the mean Cmax and AUC of isavuconazole by 75% and 97%, respectively, when coadministered with multiple doses of CRESEMBA and thus, coadministration of CRESEMBA with strong CYP3A4 inducers is contraindicated.
Figure 1. The Effect of Coadministered Drugs on Isavuconazole Exposure
The effects of isavuconazole on ritonavir, lopinavir, prednisone, combined oral contraceptives (ethinyl estradiol and norethindrone), cyclosporine, atorvastatin, sirolimus, midazolam, and tacrolimus are shown in Figure 2.
CYP3A4 Substrates
CRESEMBA increased the systemic exposure of sensitive CYP3A4 substrates midazolam, sirolimus and tacrolimus approximately 2-fold, and therefore CRESEMBA is a moderate inhibitor of CYP3A4.
Figure 2. The Effect of Isavuconazole on Coadministered CYP3A4 Substrate Medications
The effects of isavuconazole on other CYP substrates: caffeine, bupropion, methadone, repaglinide, warfarin, omeprazole, and dextromethorphan, are shown in Figure 3.
Figure 3. The Effect of Isavuconazole on Exposure of Coadministered CYP Substrate Medications
The effects of isavuconazole on the substrates of UGT and transporters: mycophenolate mofetil (MMF), methotrexate, metformin, and digoxin are shown in Figure 4.
Figure 4. The Effect of Isavuconazole on Exposure on the Substrates of UGT and Transporters
S
Vincristine
Vincristine (P-gp substrate) exposure is predicted to increase by less than 2-fold in pediatric and adult patients following concomitant administration with CRESEMBA.
Microbiology
Mechanism Of Action
Isavuconazonium sulfate is the prodrug of isavuconazole, an azole antifungal drug. Isavuconazole inhibits the synthesis of ergosterol, a key component of the fungal cell membrane, through the inhibition of cytochrome P-450 dependent enzyme lanosterol 14-alpha-demethylase. This enzyme is responsible for the conversion of lanosterol to ergosterol. An accumulation of methylated sterol precursors and a depletion of ergosterol within the fungal cell membrane weakens the membrane structure and function. Mammalian cell demethylation is less sensitive to isavuconazole inhibition.
Resistance
There is a potential for development of resistance to isavuconazole.
The mechanism of resistance to isavuconazole, like other azole antifungals, is likely due to multiple mechanisms that include substitutions in the target gene CYP51. Changes in sterol profile and elevated efflux pump activity were observed; however, the clinical relevance of these findings is unclear.
In vitro and animal studies suggest cross-resistance between isavuconazole and other azoles. The relevance of crossresistance to clinical outcome has not been fully characterized; however, patients failing prior azole therapy may require alternative antifungal therapy.
Antimicrobial Activity
Isavuconazole has activity against most strains of the following microorganisms, both in vitro and in clinical infections: Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, and Mucorales such as Rhizopus oryzae and Mucormycetes species [see Clinical Studies].
Susceptibility Testing
For specific information regarding susceptibility test interpretive criteria and associated test methods and quality control standards recognized by FDA for this drug, please see: https://www.fda.gov/STIC.
Clinical Studies
Treatment Of Invasive Aspergillosis
Trial 1 was a randomized, double-blind, non-inferiority active controlled trial which evaluated the safety and efficacy of CRESEMBA versus voriconazole for primary treatment of invasive fungal disease caused by Aspergillus species or other filamentous fungi. Eligible patients had proven, probable, or possible invasive fungal infections per European Organisation for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG) criteria1. Patients were stratified by history of allogeneic bone marrow transplant, uncontrolled malignancy at baseline, and by geographic region. The mean age of patients was 51 years (range 17-87) and the majority were Caucasians (78%), male (60%), with fungal disease involving the lungs (95%). At least one Aspergillus species was identified in 30% of the subjects; A. fumigatus and A. flavus were the most common pathogens identified. There were few patients with other Aspergillus species: A. niger, A. sydowii, A. terreus, and A. westerdijkiae. Baseline risk factors are presented in Table 9.
Table 9. Baseline Risk Factors in Intent-To-Treat (ITT1) Population
|
CRESEMBA
N=258
n (%) |
Voriconazole
N=258
n (%) |
| Hematologic Malignancy |
211 (82) |
222 (86) |
| Allogeneic Hematopoietic Stem Cell Transplant |
54 (21) |
51 (20) |
| Neutropenia2 |
163 (63) |
175 (68) |
| Corticosteroid Use |
48 (19) |
39 (15) |
| T-Cell Immunosuppressant Use |
111 (43) |
109 (42) |
1. ITT includes all randomized patients who received at least one dose of study drug.
2. Neutropenia defined as less than 500 cells/mm3 |
Patients randomized to receive CRESEMBA treatment were administered a loading dose intravenously of 372 mg of isavuconazonium sulfate (equivalent to 200 mg of isavuconazole) every 8 hours for the first 48 hours. Beginning on Day 3, patients received intravenous or oral therapy of 372 mg of isavuconazonium sulfate (equivalent to 200 mg of isavuconazole) once daily. Patients randomized to receive voriconazole treatment were administered voriconazole intravenously with a loading dose of 6 mg/kg every 12 hours for the first 24 hours followed by 4 mg/kg intravenously every 12 hours for the following 24 hours. Therapy could then be switched to an oral formulation of voriconazole at a dose of 200 mg every 12 hours. In this trial, the protocol-defined maximum treatment duration was 84 days. Mean treatment duration was 47 days for both treatment groups, of which 8 to 9 days was by an intravenous route of administration.
All-cause mortality through Day 42 in the overall population (ITT) was 18.6% in the CRESEMBA treatment group and 20.2% in the voriconazole treatment group for an adjusted treatment difference of -1.0% with 95% confidence interval of -8.0% to 5.9%. Similar results were seen in patients with proven or probable invasive aspergillosis confirmed by serology, culture or histology (see Table 10).
Table 10. All-Cause Mortality Through Day 42
|
CRESEMBA |
Voriconazole |
|
| N |
All-cause Mortality
n (%) |
N |
All-cause
Mortality
n (%) |
Difference1
(95% CI)% |
| ITT |
258 |
48 (18.6) |
258 |
52 (20.2) |
-1.0
(-8.0, 5.9) |
| Proven or Probable Invasive Aspergillosis |
123 |
23 (18.7) |
108 |
24 (22.2) |
-2.7
(-13.6, 8.2) |
| 1. Adjusted treatment difference (CRESEMBA-voriconazole) by Cochran-Mantel-Haenszel method stratified by the randomization factors. |
Overall success at End-of-Treatment (EOT) was assessed by a blinded, independent Data Review Committee (DRC) using pre-specified clinical, mycological, and radiological criteria. In the subgroup of patients with proven or probable invasive aspergillosis confirmed by serology, culture or histology, overall success at EOT was seen in 35% of CRESEMBA-treated patients compared to 38.9% of voriconazole-treated patients (see Table 11).
Table 11. Overall Response Success at End-of-Treatment
|
CRESEMBA |
Voriconazole |
|
| N |
Success
n (%) |
N |
Success
n (%) |
Difference1
(95% CI)% |
Proven or Probable
Invasive Aspergillosis |
123 |
43 (35.0) |
108 |
42
(38.9) |
-4.0
(-16.3, 8.4) |
| 1. Adjusted treatment difference (CRESEMBA-voriconazole) by Cochran-Mantel-Haenszel method stratified by the randomization factors |
Treatment Of Invasive Mucormycosis
Trial 2, an open-label, non-comparative trial, evaluated the safety and efficacy of a subset of patients with invasive mucormycosis. Thirty-seven (37) patients had proven or probable mucormycosis according to criteria based on those established by the European Organisation for Research and Treatment of Cancer/Mycoses Study Group1. Rhizopus oryzae and Mucormycetes were the most common pathogens identified. There were few patients with other Mucorales: Lichtheimia corymbifera, Mucor amphibiorum, Mucor circinelloides, Rhizomucor pusillus, Rhizopus azygosporus, and Rhizopus microsporus. The patients were white (68%), male (81%), and had a mean age of 49 years (range 22-79). Fifty-nine percent (59%) of patients had pulmonary disease involvement, half of whom also had other organ involvement. The most common non-pulmonary disease locations were sinus (43%), eye (19%), CNS (16%) and bone (14%). Baseline risk factors are presented in Table 12. The Independent Data Review Committee classified patients receiving CRESEMBA as primary therapy, or for invasive mold disease refractory to, or patients intolerant of other antifungal therapy.
Table 12. Baseline Risk Factors in Mucorales Patients
|
Primary
N=21
n (%) |
Refractory N=11
n (%) |
Intolerant N=5
n (%) |
Total N=37
n (%) |
| Hematologic Malignancy |
11 (52) |
7 (64) |
4 (80) |
22 (60) |
| Allogeneic Hematopoietic Stem Cell Transplant |
4 (19) |
4 (36) |
5 (100) |
13 (35) |
| Neutropenia1 |
4 (19) |
5 (46) |
1 (20) |
10 (27) |
| Corticosteroid Use |
5 (24) |
3 (27) |
2 (40) |
10 (27) |
| T-Cell Immunosuppressant Use |
7 (33) |
6 (55) |
5 (100) |
18 (49) |
| Diabetic |
4 (19) |
0 |
0 |
4 (11) |
Therapy status assessed by the Independent Data Review Committee: Primary = patients received CRESEMBA as primary treatment; refractory = patient’s underlying infection not adequately treated by prior therapy; intolerant = patients unable to tolerate prior therapy.
1. Neutropenia is defined as less than 500 cells/mm3. |
Patients were treated with CRESEMBA intravenously or via oral administration at the recommended doses. Median treatment duration was 102 days for patients classified as primary, 33 days for refractory, and 85 days for intolerant [see DOSAGE AND ADMINISTRATION].
For patients with invasive mucormycosis, all-cause mortality through Day 42 and success in overall response at the Endof- Treatment as assessed by the Independent Data Review Committee is shown in Table 13. These results provide evidence that CRESEMBA is effective for the treatment of mucormycosis, in light of the natural history of untreated mucormycosis. However, the efficacy of CRESEMBA for the treatment of invasive mucormycosis has not been evaluated in concurrent, controlled clinical trials.
Table 13. All-Cause Mortality and Overall Response Success in Mucorales Patients
|
Primary
N=21 |
Refractory
N=11 |
Intolerant
N=5 |
Total
N=37 |
All-cause Mortality
Through Day 42 |
7 (33%) |
5 (46%) |
2 (40%) |
14 (38%) |
Overall Response
Success Rate at End-of-Treatment |
6/191 (32%) |
4/11 (36%) |
1/5 (20%) |
11/351 (31%) |
| 1. Two primary mucormycosis patients were not assessed at End-of-Treatment due to ongoing treatment. |
REFERENCES
1. DePauw, B., Walsh, T.J., Donnelly, J.P., et al. (2008) Revised Definitions of Invasive Fungal Disease from the European Organization for Research and Treatment of Cancer Invasive Fungal Infections Quadrature Group and National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) consensus group. Clinical Infectious Diseases 46:1813-1821.