Pharmacotherapeutic group: Antimycotics for systemic use, triazole derivatives, ATC code: J02AC04.
Mechanism of action
Posaconazole inhibits the enzyme lanosterol 14α-demethylase (CYP51), which catalyses an essential step in ergosterol biosynthesis.
Microbiology
Posaconazole has been shown in vitro to be active against the following microorganisms: Aspergillus species (Aspergillus fumigatus, A. flavus, A. terreus, A. nidulans, A. niger, A. ustus), Candida species (Candida albicans, C. glabrata, C. krusei, C. parapsilosis, C. tropicalis, C. dubliniensis, C. famata, C. inconspicua, C. lipolytica, C. norvegensis, C. pseudotropicalis), Coccidioides immitis, Fonsecaea pedrosoi, and species of Fusarium, Rhizomucor, Mucor, and Rhizopus. The microbiological data suggest that posaconazole is active against Rhizomucor, Mucor, and Rhizopus; however the clinical data are currently too limited to assess the efficacy of posaconazole against these causative agents.
The following in vitro data are available, but their clinical significance is unknown. In a surveillance study of > 3,000 clinical mold isolates from 2010-2018, 90 % of non-Aspergillus fungi exhibited the following in vitro minimum inhibitory concentration (MIC): Mucorales spp (n=81) of 2 mg/L; Scedosporium apiospermum/S. boydii (n=65) of 2 mg/L; Exophiala dermatiditis (n=15) of 0.5 mg/L, and Purpureocillium lilacinum (n=21) of 1 mg/L.
Resistance
Clinical isolates with decreased susceptibility to posaconazole have been identified. The principle mechanism of resistance is the acquisition of substitutions in the target protein, CYP51.
Epidemiological Cut-off (ECOFF) Values for Aspergillus spp.
The ECOFF values for posaconazole, which distinguish the wild type population from isolates with acquired resistance, have been determined by EUCAST methodology.
EUCAST ECOFF values:
• Aspergillus flavus: 0.5 mg/L
• Aspergillus fumigatus: 0.5 mg/L
• Aspergillus nidulans: 0.5 mg/L
• Aspergillus niger: 0.5 mg/L
• Aspergillus terreus: 0.25 mg/L
There are currently insufficient data to set clinical breakpoints for Aspergillus spp. ECOFF values do not equate to clinical breakpoints.
Breakpoints
EUCAST MIC breakpoints for posaconazole [susceptible (S); resistant (R)]:
• Candida albicans: S ≤0.06 mg/L, R >0.06 mg/L
• Candida tropicalis: S ≤0.06 mg/L, R >0.06 mg/L
• Candida parapsilosis: S ≤0.06 mg/L, R >0.06 mg/L
• Candida dubliniensis: S ≤0.06 mg/L, R >0.06 mg/L
There are currently insufficient data to set clinical breakpoints for other Candida species.
Combination with other antifungal agents
The use of combination antifungal therapies should not decrease the efficacy of either posaconazole or the other therapies; however, there is currently no clinical evidence that combination therapy will provide an added benefit.
Pharmacokinetic / Pharmacodynamic relationships
A correlation between total medicinal product exposure divided by MIC (AUC/MIC) and clinical outcome was observed. The critical ratio for subjects with Aspergillus infections was ~200. It is particularly important to try to ensure that maximal plasma levels are achieved in patients infected with Aspergillus (see sections 4.2 and 5.2 on recommended dose regimens and the effects of food on absorption).
Clinical experience
Summary of posaconazole oral suspension studies
Invasive aspergillosis
Oral posaconazole suspension 800 mg/day in divided doses was evaluated for the treatment of invasive aspergillosis in patients with disease refractory to amphotericin B (including liposomal formulations) or itraconazole or in patients who were intolerant of these medicinal products in a non-comparative salvage therapy study (Study 0041). Clinical outcomes were compared with those in an external control group derived from a retrospective review of medical records. The external control group included 86 patients treated with available therapy (as above) mostly at the same time and at the same sites as the patients treated with posaconazole. Most of the cases of aspergillosis were considered to be refractory to prior therapy in both the posaconazole group (88 %) and in the external control group (79 %).
As shown in Table 3, a successful response (complete or partial resolution) at the end of treatment was seen in 42 % of posaconazole-treated patients compared to 26 % of the external group. However, this was not a prospective, randomised controlled study and so all comparisons with the external control group should be viewed with caution.
Table 3. Overall efficacy of posaconazole oral suspension at the end of treatment for invasive aspergillosis in comparison to an external control group
| | Posaconazole oral suspension | External control group |
| Overall Response | 45/107 (42 %) | 22/86 (26 %) |
| Success by Species |
| All mycologically confirmed Aspergillus spp.1 | 34/76 | (45 %) | 19/74 | (26 %) |
| A. fumigatus | 12/29 | (41 %) | 12/34 | (35 %) |
| A. flavus | 10/19 | (53 %) | 3/16 | (19 %) |
| A. terreus | 4/14 | (29 %) | 2/13 | (15 %) |
| A. niger | 3/5 | (60 %) | 2/7 | (29 %) |
Fusarium spp.
11 of 24 patients who had proven or probable fusariosis were successfully treated with posaconazole oral suspension 800 mg/day in divided doses for a median of 124 days and up to 212 days. Among eighteen patients who were intolerant or had infections refractory to amphotericin B or itraconazole, seven patients were classed as responders.
Chromoblastomycosis/Mycetoma
9 of 11 patients were successfully treated with posaconazole oral suspension 800 mg/day in divided doses for a median of 268 days and up to 377 days. Five of these patients had chromoblastomycosis due to Fonsecaea pedrosoi and 4 had mycetoma, mostly due to Madurella species.
Coccidioidomycosis
11 of 16 patients were successfully treated (at the end of treatment complete or partial resolution of signs and symptoms present at baseline) with posaconazole oral suspension 800 mg/day in divided doses for a median of 296 days and up to 460 days.
Treatment of azole-susceptible Oropharyngeal Candidiasis (OPC)
A randomised, evaluator-blind, controlled study was completed in HIV-infected patients with azole-susceptible oropharyngeal candidiasis (most patients studied had C. albicans isolated at baseline). The primary efficacy variable was the clinical success rate (defined as cure or improvement) after 14 days of treatment. Patients were treated with posaconazole or fluconazole oral suspension (both posaconazole and fluconazole were given as follows: 100 mg twice a day for 1 day followed by 100 mg once a day for 13 days).
The clinical response rates from the above study are shown in the Table 4 below.
Posaconazole was shown to be non-inferior to fluconazole for clinical success rates at Day 14 as well as 4 weeks after the end of treatment.
Table 4. Clinical success rates in Oropharyngeal Candidiasis
| Endpoint | Posaconazole | Fluconazole |
| Clinical success rate at Day 14 | 91.7 % (155/169) | 92.5 % (148/160) |
| Clinical success rate 4 weeks after end of treatment | 68.5 % (98/143) | 61.8 % (84/136) |
Clinical success rate was defined as the number of cases assessed as having a clinical response (cure or improvement) divided by the total number of cases eligible for analysis.
Prophylaxis of Invasive Fungal Infections (IFIs) (Studies 316 and 1899)
Two randomised, controlled prophylaxis studies were conducted among patients at high-risk for developing invasive fungal infections.
Study 316 was a randomised, double-blind study of posaconazole oral suspension (200 mg three times a day) versus fluconazole capsules (400 mg once daily) in allogeneic hematopoietic stem cell transplant recipients with graft-versus-host disease (GVHD). The primary efficacy endpoint was the incidence of proven/probable IFIs at 16 weeks post-randomisation as determined by an independent, blinded external expert panel. A key secondary endpoint was the incidence of proven/probable IFIs during the on-treatment period (first dose to last dose of study medicinal product + 7 days). The majority (377/600, [63 %]) of patients included had Acute Grade 2 or 3 or chronic extensive (195/600, [32.5 %]) GVHD at study start. The mean duration of therapy was 80 days for posaconazole and 77 days for fluconazole.
Study 1899 was a randomised, evaluator-blinded study of posaconazole oral suspension (200 mg three times a day) versus fluconazole suspension (400 mg once daily) or itraconazole oral solution (200 mg twice a day) in neutropenic patients who were receiving cytotoxic chemotherapy for acute myelogenous leukaemia or myelodysplastic syndromes. The primary efficacy endpoint was the incidence of proven/probable IFIs as determined by an independent, blinded external expert panel during the on-treatment period. A key secondary endpoint was the incidence of proven/probable IFIs at 100 days post-randomisation. New diagnosis of acute myelogenous leukaemia was the most common underlying condition (435/602, [72 %]). The mean duration of therapy was 29 days for posaconazole and 25 days for fluconazole/itraconazole.
In both prophylaxis studies, aspergillosis was the most common breakthrough infection. See Table 5 and 6 for results from both studies. There were fewer breakthrough Aspergillus infections in patients receiving posaconazole prophylaxis when compared to control patients.
Table 5. Results from clinical studies in prophylaxis of Invasive Fungal Infections
| Study | Posaconazole oral suspension | Controla | P-Value |
| Proportion (%) of patients with proven/probable IFIs |
| On-treatment periodb |
| 1899d | 7/304 (2) | 25/298 (8) | 0.0009 |
| 316e | 7/291 (2) | 22/288 (8) | 0.0038 |
| Fixed-time periodc |
| 1899d | 14/304 (5) | 33/298 (11) | 0.0031 |
| 316 d | 16/301 (5) | 27/299 (9) | 0.0740 |
FLU = fluconazole; ITZ = itraconazole; POS = posaconazole.
a: FLU/ITZ (1899); FLU (316).
b: In 1899 this was the period from randomisation to last dose of study medicinal product plus 7 days; in 316 it was the period from first dose to last dose of study medicinal product plus 7 days.
c: In 1899, this was the period from randomisation to 100 days post-randomisation; in 316 it was the period from the baseline day to 111 days post-baseline.
d: All randomised
e: All treated
Table 6. Results from clinical studies in prophylaxis of Invasive Fungal Infections
| Study | Posaconazole oral suspension | Controla |
| Proportion (%) of patients with proven/probable Aspergillosis |
| On-treatment periodb |
| 1899d | 2/304 (1) | 20/298 (7) |
| 316e | 3/291 (1) | 17/288 (6) |
| Fixed-time periodc |
| 1899d | 4/304 (1) | 26/298 (9) |
| 316 d | 7/301 (2) | 21/299 (7) |
FLU = fluconazole; ITZ = itraconazole; POS = posaconazole.
a: FLU/ITZ (1899); FLU (316).
b: In 1899 this was the period from randomisation to last dose of study medicinal product plus 7 days; in 316 it was the period from first dose to last dose of study medicinal product plus 7 days.
c: In 1899, this was the period from randomisation to 100 days post-randomisation; in 316 it was the period from the baseline day to 111 days post-baseline.
d: All randomised
e: All treated
In Study 1899, a significant decrease in all-cause mortality in favour of posaconazole was observed [POS 49/304 (16 %) vs. FLU/ITZ 67/298 (22 %) p= 0.048]. Based on Kaplan-Meier estimates, the probability of survival up to day 100 after randomisation, was significantly higher for posaconazole recipients; this survival benefit was demonstrated when the analysis considered all causes of death (P= 0.0354) as well as IFI-related deaths (P= 0.0209).
In Study 316, overall mortality was similar (POS, 25 %; FLU, 28 %); however, the proportion of IFI-related deaths was significantly lower in the POS group (4/301) compared with the FLU group (12/299; P= 0.0413).
Paediatric population
No dose of posaconazole oral suspension could be recommended for paediatric patients. However, the safety and efficacy of other formulations of posaconazole (Noxafil gastro-resistant powder and solvent for oral suspension; Noxafil concentrate for solution for infusion) have been established in paediatric patients 2 to less than 18 years of age. Refer to their SmPC for additional information.
Electrocardiogram evaluation
Multiple, time-matched ECGs collected over a 12-hour period were obtained before and during administration of posaconazole oral suspension (400 mg twice daily with high fat meals) from 173 healthy male and female volunteers aged 18 to 85 years. No clinically relevant changes in the mean QTc (Fridericia) interval from baseline were observed.
1 Includes other less common species or species unknown