Efficacy of aerosolized liposomal amphotericin B against murine invasive pulmonary mucormycosis

Case report: A case of pulmonary mucormycosis caused by Rhizopus azygosporus infection complicated by type 2 diabetes mellitus

A case of pulmonary mucormycosis (PM) caused by Rhizopus azygosporus infection complicated by type 2 diabetes mellitus is reported. An adult male patient had a productive cough for more than 10 days, aggravated by blood in the sputum for 9 days. Laboratory examination confirmed that he had had type 2 diabetes mellitus and diabetic ketosis for more than 3 years, and his chest computed tomography (CT) scan showed lesions, cavities, and a small effusion in the right lower lobe. The lavage fluid was taken by bronchoscope for bacterial culture and mNGS, which indicated Rhizopus azygosporus growth. Mucormycosis was diagnosed. The patient was given amphotericin B cholesterol sulfate complex for 30 days, and his renal function was closely monitored. After that, his right lower lobe was resected. To date, the patient has recovered well.

Treatment of pulmonary mucormycosis with adjunctive nebulized amphotericin B (MUCONAB trial): Results of an open-label randomized controlled trial

BACKGROUND

The role of nebulized amphotericin B (NAB) in managing pulmonary mucormycosis (PM) is unknown.

METHODS

In this open-label trial, we randomized PM subjects to receive either intravenous liposomal amphotericin B (control arm, 3-5 mg/kg/day) alone or along with nebulized amphotericin B deoxycholate (NAB, 10 mg twice a day, every alternate day). The primary outcomes were: (1) overall response ('success' [complete or partial response] or 'failure' [stable disease, progressive disease, or death]) at 6 weeks; and (2) the proportion of subjects with adverse events (AE). The key secondary outcome was 90-day mortality. We performed a modified intention-to-treat (mITT) analysis where we included only subjects receiving at least a single dose of NAB.

RESULTS

Fifteen and 17 subjects were randomized to the control and NAB arms; two died before the first dose of NAB. Finally, we included 30 subjects (15 in each arm; mean age 49.8 years; 80% men) for the mITT analysis. Diabetes mellitus (n = 27; 16/27 were COVID-19-associated PM) was the most common predisposing factor. The overall treatment success was not significantly different between the control and the NAB arms (71.4% vs. 53.3%; p = .45). Twenty-nine subjects experienced any AE, but none discontinued treatment. The 90-day mortality was not significantly different between the control (28.6%) and NAB arm (53.3%; p = .26).

CONCLUSION

Adjunctive NAB was safe but did not improve overall response at 6 weeks. A different dosing schedule or nebulized liposomal amphotericin B may still need evaluation. More research is needed to explore other treatment options for PM.

Could the Lung Be a Gateway for Amphotericin B to Attack the Army of Fungi?

Fungal diseases are a significant cause of morbidity and mortality worldwide, primarily affecting immunocompromised patients. Aspergillus, Pneumocystis, and Cryptococcus are opportunistic fungi and may cause severe lung disease. They can develop mechanisms to evade the host immune system and colonize or cause lung disease. Current fungal infection treatments constitute a few classes of antifungal drugs with significant fungi resistance development. Amphotericin B (AmB) has a broad-spectrum antifungal effect with a low incidence of resistance. However, AmB is a highly lipophilic antifungal with low solubility and permeability and is unstable in light, heat, and oxygen. Due to the difficulty of achieving adequate concentrations of AmB in the lung by intravenous administration and seeking to minimize adverse effects, nebulized AmB has been used. The pulmonary pathway has advantages such as its rapid onset of action, low metabolic activity at the site of action, ability to avoid first-pass hepatic metabolism, lower risk of adverse effects, and thin thickness of the alveolar epithelium. This paper presented different strategies for pulmonary AmB delivery, detailing the potential of nanoformulation and hoping to foster research in the field. Our finds indicate that despite an optimistic scenario for the pulmonary formulation of AmB based on the encouraging results discussed here, there is still no product registration on the FDA nor any clinical trial undergoing ClinicalTrial.gov.

Inhaled Antifungal Agents for Treatment and Prophylaxis of Bronchopulmonary Invasive Mold Infections

Pulmonary mold infections are life-threatening diseases with high morbi-mortalities. Treatment is based on systemic antifungal agents belonging to the families of polyenes (amphotericin B) and triazoles. Despite this treatment, mortality remains high and the doses of systemic antifungals cannot be increased as they often lead to toxicity. The pulmonary aerosolization of antifungal agents can theoretically increase their concentration at the infectious site, which could improve their efficacy while limiting their systemic exposure and toxicity. However, clinical experience is poor and thus inhaled agent utilization remains unclear in term of indications, drugs, and devices. This comprehensive literature review aims to describe the pharmacokinetic behavior and the efficacy of inhaled antifungal drugs as prophylaxes and curative treatments both in animal models and humans.

Management of Pulmonary Mucormycosis After Orthotopic Heart Transplant: A Case Series

Invasive pulmonary mucormycosis is a potentially fatal infection that can occur in immunosuppressed patients such as those who have undergone orthotopic heart transplant (OHT). High-dose intravenous antifungal agents, including amphotericin B, are generally accepted as the first-line medical treatment, with prompt surgical resection of lesions if feasible. The body of evidence guiding treatment decisions, however, is sparse, particularly regarding adjustment of immunosuppression during acute infection and long-term recovery. We present 2 cases of patients with pulmonary mucormycosis occurring within the first 6 months after OHT, both of whom successfully recovered after appropriate medical and surgical treatment, and we highlight differences in immunosuppression management strategies for this life-threatening condition.

Inhaled Antifungal Agents for the Treatment and Prophylaxis of Pulmonary Mycoses

Pulmonary mycoses are associated with high morbidity and mortality. The current standard treatment by systemic administration is limited by inadequate local bioavailability and systemic toxic effects. Aerosolisation of antifungals is an attractive approach to overcome these problems, but no inhaled antifungal formulation is currently available for the treatment of pulmonary mycoses. Hence, the development of respirable antifungals formulations is of interest and in high demand. In this review, the recent advances in the development of antifungal formulations for pulmonary delivery are discussed, including both nebulised and dry powder formulations. Although the clinical practices of nebulised parenteral amphotericin B and voriconazole formulations (off-label use) are reported to show promising therapeutic effects with few adverse effects, there is no consensus about the dosage regimen (e.g. the dose, frequency, and whether they are used as single or combination therapy). To maximise the benefits of nebulised antifungal therapy, it is important to establish standardised protocol that clearly defines the dose and specifies the device and the administration conditions. Dry powder formulations of antifungal agents such as itraconazole and voriconazole with favourable physicochemical and aerosol properties are developed using various powder engineering technologies, but it is important to consider their suitability for use in patients with compromised lung functions. In addition, more biological studies on the therapeutic efficacy and pharmacokinetic profile are needed to demonstrate their clinical potential.

Mucormycosis treatment: Recommendations, latest advances, and perspectives

Mucormycosis are life-threatening fungal infections especially affecting immunocompromised or diabetic patients. Despite treatment, mortality remains high (from 32 to 70% according to organ involvement). This review provides an update on mucormycosis management. The latest recommendations strongly recommend as first-line therapy the use of liposomal amphotericin B (≥5mg/kg) combined with surgery whenever possible. Isavuconazole and intravenous or delayed-release tablet forms of posaconazole have remained second-line. Many molecules are currently in development to fight against invasive fungal diseases but few have demonstrated efficacy against Mucorales. Despite in vitro efficacy, combinations of treatment have failed to demonstrate superiority versus monotherapy. Adjuvant therapies are particularly complex to evaluate without prospective randomized controlled studies, which are complex to perform due to low incidence rate and high mortality of mucormycosis. Perspectives are nonetheless encouraging. New approaches assessing relationships between host, fungi, and antifungal drugs, and new routes of administration such as aerosols could improve mucormycosis treatment.

Lichtheimia corymbifera Colonization Leading to Pulmonary Infection Can Be Prevented with Liposomal Amphotericin B in a New Murine Model

The incidence of pulmonary mucormycosis is constantly increasing, especially in hematological patients staying in high-efficiency particulate air-filtered rooms. Pulmonary inhalation of spores may occur outside the hospital, leading to invasive disease once patients received chemotherapies. We developed a new pulmonary mucormycosis mouse model mimicking the expected pathophysiology in human to study antifungal drugs. Naive mice were inoculated intratracheally with Lichtheimia corymbifera spores. After 3 days, mice received corticosteroids and cyclophosphamide and secondarily developed the disease, while only 5% of the initial inoculum was present in the lungs at day 3. Lung colonization with L. corymbifera spores in immunocompetent mice can last at least 44 days. Antifungal drug was administered the day of immunosuppression. Injection of a single 15 mg/kg of body weight dose of liposomal amphotericin B significantly improved survival and pulmonary fungal burden compared with controls, whereas 80 mg/kg oral posaconazole did not. These results show that a unique dose of liposomal amphotericin B offers a real potential decolonization treatment to prevent infection in our mouse model of L. corymbifera lung colonization followed by lung infection.

Animal Models to Study Mucormycosis

Mucormycosis is a rare but often fatal or debilitating infection caused by a diverse group of fungi. Animal models have been crucial in advancing our knowledge of mechanisms influencing the pathogenesis of mucormycoses, and to evaluate therapeutic strategies. This review describes the animal models established for mucormycosis, summarizes how they have been applied to study mucormycoses, and discusses the advantages and limitations of the different model systems.

Fungal diseases: could nanostructured drug delivery systems be a novel paradigm for therapy?

Invasive mycoses are a major problem for immunocompromised individuals and patients in intensive care units. Morbidity and mortality rates of these infections are high because of late diagnosis and delayed treatment. Moreover, the number of available antifungal agents is low, and there are problems with toxicity and resistance. Alternatives for treating invasive fungal infections are necessary. Nanostructured systems could be excellent carriers for antifungal drugs, reducing toxicity and targeting their action. The use of nanostructured systems for antifungal therapy began in the 1990s, with the appearance of lipid formulations of amphotericin B. This review encompasses different antifungal drug delivery systems, such as liposomes, carriers based on solid lipids and nanostructure lipids, polymeric nanoparticles, dendrimers, and others. All these delivery systems have advantages and disadvantages. Main advantages are the improvement in the antifungal properties, such as bioavailability, reduction in toxicity, and target tissue, which facilitates innovative therapeutic techniques. Conversely, a major disadvantage is the high cost of production. In the near future, the use of nanosystems for drug delivery strategies can be used for delivering peptides, including mucoadhesive systems for the treatment of oral and vaginal candidiasis.