Inhaled antifungal therapy: benefits, challenges, and clinical applications

Figures & data

Figure 1. Schematic illustration of the fate of inhaled Aspergillus conidia, and opportunity of inhaled antifungal therapy. Inhaled conidia or germinated hypha are often cleared up by resident macrophages or neutrophils. Survived hypha is branching and grows, forming biofilm. On some occasions, fungus forms fungal ball in lung lumen, and in immunocompromised condition, fungus invades systemically. There are different treatment options/regimen at different infection stage.

Table 1. Preclinical evidence of beneficial effects of inhaled antifungals.

Antifungals	Class of antifungal	Animals	Delivery system and device	Dose	Outcome	source
Amphotericin B (AmB)	Polyene	Guinea pig	A rotating brush aerosol generator (RBG 1000, Palas®)	Dry-powder formulation (50% AmB in an 18-carbon lipid excipient, distearoylphosphatidylcholine)	Single-dose prophylaxis (24 hr prior to infection) with AmB inhalation powder demonstrated a significant survival advantage and reductions in pulmonary fungal burden in this model of invasive pulmonary aspergillosis.	Kirkpatrick W (2012)[46]
Itraconazole	Triazole	Quails	Neublised using Pariboy SX with PARI LC Sprint nebulizer equipped with red insert for fine droplets	10% nanosuspension containing 4% ITRA	Inhaled itraconazole blocked lethality and prevented disease-related symptoms in the quails exposed to the low dose of spores of Aspergillus fumigatus.	Wlaz P (2015)[47]
Opelconazole (PC945)	Triazole	Mouse	Intranasal, saline suspension	0.56 to 350 μg/mouse	Improved survival reduced fungal burden and serum/BAL biomarkers (galactomannan, CXCL1) in Aspergillus fumigatus and Candida albicans infected immunocompromised mice. Marked synergic effects with systemic (oral) Posaconazole treatment were observed in vitro (bilayer system) and in vivo.	Ito K (2021)[101] Nishimoto Y (2021)[48] Colley T (2019)[93] Kimura G (2017)[49] Colley T (2017)[50]
PC1244	Triazole	Mouse	Intranasal, saline suspension	0.56–70 μg/mouse	Improved survival, reduced fungal burden and serum/BAL biomarkers (galactomannan, CXCL1) in Aspergillus fumigatus (azole susceptible and resistant) infected immunocompromised mice.	Colley T (2019)[51] Colley T (2017)[52]
Pneumocandins	Echinocandin-like	rat	Aerosolised in a glass chamber filled with a stream of nebulized compound created by air flowing at 8 liters/min through a nebulizer (Cadema Medical Products)	L-693,989 (10 mg/kg) and AmB (0.8 mg/kg) in saline	Aerosol L-693,989 administered 2 h before infection (5 mg/kg) delayed mortality in a rat model of pulmonary aspergillosis. All aerosolized AmB treated animals were alive at the end of the 7-day observation period.	Kurz MB (1995)[53]
Posaconazole	Triazole	Mouse	Intranasal, saline suspension	2.8–350 μg/mouse	Improved survival, reduced fungal burden and serum/BAL biomarkers (galactomannan, CXCL1) in Aspergillus fumigatus infected immunocompromised mice (equivalent to or better than oral treatment).	Kimura G (2017)[54]
PUR1900	Triazole	Guinea pigs	Inhaled dry powder formulation of itraconazole, iSPERSE^TM technology. Direct flow inhalation system via a central annulus.	0 or 30 mg/kg/day of inhaled PUR1900, daily for 10 days starting form −1Day before inoculation)	Inhaled PUR1900 resulted in a significantly higher pulmonary exposure to itraconazole relative to oral treatment. Inhaled PUR1900 treatment reduced clinical signs of infection, prevented weight loss and significantly improved survival in an immunocompromised, Aspergillus-infected Guinea-pig model.	Curran AK (2018)[76]
Voriconazole	Triazole	Mouse	Nebulization of intravenous formulation in a nose-only dosing chamber by an Aeroneb Pro micropump nebulizer system.	5mL of 6.25 mg/ml	Inhaled voriconazole (from 2 days prior to pulmonary inoculation until day 7 post-inoculation) significantly improved survival and limited the extent of invasive disease, as assessed by histopathology, compared to control and AmB.	Tolman JA (2009)[69]

BAL: Bronchoalveolar lavage, CXCL1: Chemokine (C-X-C motif) ligand 1, IV: Intravenous, iSPERSE: Inhaled small particles easily respirable and emitted

Table 2. Clinical evidence of beneficial effects of inhaled antifungals by off-label use.

Antifungals	Class of antifungal	Treatment	Delivery system	Target population	Outcome	source
Amphotericin B (AmB)	Polyene	Inhaled liposomal AmB prophylaxis. 12.5 mg Ambisome®, dissolved in 3mL of sterile water	Covidien® DAR® nebulizer set in all intubated patients.	COVID19-associated pulmonary aspergillosis. all intubated patients.	Reduced the incidence of CAPA.	Van Ackerbroeck S (2021)[55]
		Nebulized AmB deoxycholate Fungizone® (10 mg in 4mL water)	Breath-enhanced jet nebulizer (Pari LC Sprint)	Various forms of pulmonary aspergillosis	Poorly tolerated (66% only) due to increased breathlessness. Some patients showed total/Af IgE, Af-IgG(↓)	Otu AA (2019)[56]
		Nebulized AmB deoxycholate Fungizone® (5 mg/mL)	Jet nebulizer (Pulmo-Mist II)	ABPA	Frequency of exacerbation (↓ vs. nebulized budesonide), 3 patients, bronchospasm after nebulization of AmB	Ram B (2016)[57]
		Inhaled liposomal AmB prophylaxis 12.5 mg Ambisome®	Prodose® AAD nebulizer or Akita® AAD nebulizer	AML	Less IPA (9.5% vs. 23.4% control), less systemic antifungal required, well tolerated	Chong G-L M (2015)[58]
		Nebulized AmB deoxycholate Fungizone® (10 mg in 4mL water)	Breath‐enhanced jet nebulizer (Pari LC Sprint)	Severe asthma (SAFS/ABPA)	14% (3/21) Clinical benefit 33% (7/21), failed initial dose due to Bronchospasm, 52% (11/21), discontinued within 12 M	Chishimba L (2014)[67]
		Inhaled AmB deoxycholate prophylaxis 25 mg of D-AmB for IV infusion is dissolved in 5 mL of sterile water.	Nebulizer (not specified)	AlloSCT with GvHD	Less IPA (2.5% vs. 6.6% wo AmB), better survival rate. Well tolerated.	Nihtinen A (2012)[59]
		Inhaled liposomal AmB prophylaxis 12.5 mg Ambisome®	Jet stream nebulizers (LC Star)	AML and allogeneic SCT	No difference on IPA incidence, better 1 year survival (80% vs. 54% control), unpleasant (cough/nausea), but no serious side effect	Hullard-Pulstinger A (2011)[60]
		Inhaled liposomal AMB prophylaxis 50 mg Ambisome® in 12mL of sterile water	Jet nebulizer (Ventstream or Sidestream, Respironics) with a CR60 compressor	Lung transplant patients (PK study)	AmB concentrations after n-LAB remained high for 14 days, at adequate concentrations for prophylaxis of Aspergillus infection. No significant systemic absorption of AmB was detected, and no effect was observed on respiratory function.	Monforte V (2009) [61,68]
		Inhaled liposomal AMB prophylaxis 2.5mL of a 5-mg/mL solution of Ambisome®	Adaptive aerosol delivery system (Halolite AAD or ProDose AAD)	Hematologic disease with expected neutropenia	Less IPA incidence (4% vs. 14% placebo), Higher Cough/Discontinuation, no serious side effect	Rijnders BJ (2008)[62]
		Inhaled AMB deoxycholate prophylaxis 10 mg Fungizone® in 5mL of sterile water	RespirGard II, PariBoy or Pari IS II	AML/MDS/CML, ALL, NHL, auto- BMT	No difference on IPA (4% vs. 7% wo AMB) and mortality (8% vs. 7%), cough/nausea/bad taste	Schwartz S (1999)[66]
Natamycin	Polyene	5 mg in 3mL of 0.9% saline	Through a mouthpiece, an Inspiron nebulizer powered by a Portaneb 50 compressor.	ABPA	17 patients (9 natamycin, 8 placebo) completed. No evidence that natamycin conferred benefit on ABPA.	Currie DC (1990)[63]
Opelconazole	Triazole	Nebulized, 5 mg once or twice daily	Breath‐enhanced jet nebulizer (Pari LC Sprint)	Invasive pulmonary aspergillosis due to infections with A. fumigatus complex, shortly following lung transplantation	One month later, the anastomosis appeared normal with no microbiological evidence of fungal infection.	Pagani N (2020)[64] Murray A (2021)[90]
Posaconazole	Triazole	Nebulized or intrabronchial, daily Naxafil® for injection, diluted to 2 mg/ml of sterile saline	eFlow rapid device	Lung transplant, invasive tracheobronchial and lung Scedosporium apiospermum infections	In 2 of 3 cases, the infection was clinically and radiologically cured with frequent cleansing bronchoscopies, combining triazole with terbinafine therapy and nebulized posaconazole.	Sole A (2018)[65]
Voriconazole	Triazole	Aerosolized VOR 40 mg t.i.d. → b.i.d. after 2 weeks The dry powder formulation of voriconazole (200 mg) for i.v. use, diluted in 20mL of water.	Jet nebulizer (Sidestream®) with a Portaneb compressor.	Invasive aspergillosis (Systemic antifungal no effect or poorly tolerated)	Remarkable effects on CRP and Chest radiography or lung function (n = 3).	Hilberg O (2012)[70] (PK of inhaled VOR), Andersen CU (2017)[71]
		Aerosolized VOR 40 mg once daily Vfend®for iv use	Nebulization (not specified)	Severe pulmonary infection with Scedosporium apiospermum in an adolescent with CF.	Improved lung function and Chest-CT scan. Very well tolerated	Holle J (2014)[72]

ABPA: Allergic bronchopulmonary aspergillosis, Af: Asperigillus fumigatus, ALL: Acute lymphocytic leukemia, AmB: Amphotericin B, AML: Acute myeloid leukemia, BMT: Bone marrow transplantation, CAPA: COVID19 associated pulmonary aspergillosis, CML: Chronic myelogenous leukemia, COVID19: Coronavirus disease 2019, CRP: c-reactive protein, IPA: Invasive pulmonary aspergillosis, MDS: Myelodysplastic syndromes, NHL: Non-Hodgkin lymphoma, SAFS: Severe asthma with fungal sensitization, SCT: Stem cell transplant

Table 3. Novel inhaled antifungals in clinical phase.

Antifungals	API	Company	Delivery systems	Current status	Source
Opelconazole	PC945	Pulmocide Ltd.	Nebulization	Phase 2	Phase 1 (completed) (NCT02715570) Phase 2a (CF) (NCT03870841) Terminated due to COVID19 pandemic Phase 2a (asthma) (NCT03745196) Terminated due to COVID19 pandemic Phase 2 (pulmonary aspergillosis in lung transplant patients) (NCT05037851) Phase 2 (refractory invasive pulmonary aspergillosis) (NCT05238116)
Pulmazole (PUR1900)	Itraconazole	Pulmatrix Inc.	Dry Powder (RS01 Monodose inhaler)	Phase 2a	Phase 1 (NCT03479411) completed Phase 2a (ABPA) (NCT03960606) [terminated due to COVID-19 pandemic]
TFF-voriconazole	Voriconazole	TFF Pharmaceuticals, Inc.	Dry Powder (Plastiape RS00 Dry Powder inhaler)	Phase 1	Phase 1 (completed) (NCT04872231) (NCT04576325) asthma
ZP-059	N-oxide voriconazole	Zambon SpA	Dry Powder (dry powder inhaler (DPI	Phase 1	Phase 1 (completed) (NCT04229303)

Figure 2. Preclinical in vitro assay method for inhaled antifungals. a) air-liquid interface cultured pseudostratified epithelium (nasal, bronchial, small airway). b) bilayer alveolus model [98]. Black freeform scribble: fungus body. c) A. fumigatus infection in bilayer (apical phase). Histology of alveolus model d) non-infected, e) 48 h post infection with A. fumigatus conidia. Solid arrow: Conidial head and conidiophore, Dotted arrow: hyphae and foot cell, White arrow: original endothelial and epithelial cell bilayer.

Figure 3. Factors affecting lung exposure and distribution of inhaled-antifungal agent. AHR: airway hyperresponsiveness.

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