Breakthrough Rhizopus infection on posaconazole prophylaxis following allogeneic stem cell transplantation

In Vitro Antifungal Drug Resistance Profiles of Clinically Relevant Members of the Mucorales (Mucoromycota) Especially with the Newer Triazoles

Mucoromycoses (infections caused by members of the order Mucorales, phylum Mucoromycota [ex-Zygomycota]) are highly destructive, rapidly progressive infections, with dire prognoses especially when they occur in immunocompromised hosts. Current treatment guidelines recommend liposomal formulations of amphotericin B with adjunctive surgery as first line therapy, with the newer triazoles posaconazole or isavuconazole as alternative treatments, or as salvage therapy. Among the many organisms belonging to this order, a limited number of species in the genera Rhizopus, Mucor, Lichtheimia and Rhizomucor are responsible for most cases of human infection. Here, we present the minimum inhibitory concentration data (MICs) for amphotericin B, posaconazole, isavuconazole, itraconazole and voriconazole with a panel of over 300 isolates of the five most common agents of human infection (Lichtheimia corymbifera, Rhizopus arrhizus, R. microsporus, Rhizomucor pusillus and Mucor spp.) determined using the CLSI broth microdilution method. In agreement with previous studies, the most active antifungal drug for all Mucorales was amphotericin B, with MICs within the range that would predict susceptibility with Aspergillus fumigatus. Conversely, MICs for voriconazole against all species tested were high, and above the range associated with clinical efficacy with A. fumigatus. Interestingly, whilst isavuconazole and posaconazole MIC distributions indicated in vitro activity against some members of the Mucorales, activity was species-dependent for both agents. These data underscore the importance of accurate identification of the causative agents of mucoromycosis, coupled with antifungal susceptibility testing of individual isolates, in determining the optimal treatment of infections caused by these aggressive opportunistic human fungal pathogens.

Foiling fungal disease post hematopoietic cell transplant: review of prophylactic strategies

Hematopoietic cell transplantation (HCT) offers definitive management for a wide variety of malignant and nonmalignant diseases. Conditioning regimens and therapies used to prevent and treat GvHD are immune suppressive, often increasing the risk of developing fungal disease due to yeasts or molds. Antifungal prophylaxis may be useful in preventing morbidity and mortality during and after HCT. In this article, we review the epidemiology and current literature regarding strategies for prevention of invasive fungal disease (IFD) in the pre-engraftment and post-engraftment settings, and propose future direction for scientific discovery.

Prophylactic Treatment with VT-1161 Protects Immunosuppressed Mice from Rhizopus arrhizus var. arrhizus Infection

We compared prophylactic or continuous therapy with the investigational drug VT-1161 to that with posaconazole in treating murine mucormycosis due to Rhizopus arrhizus var. arrhizus In the prophylaxis studies, only VT-1161 resulted in improved survival and lowered tissue fungal burden of immunosuppressed infected mice. In the continuous therapy, VT-1161 outperformed posaconazole in prolonging mouse survival time despite its comparable effect in lowering tissue fungal burden. These results support the further development of VT-1161 against mucormycosis.

Prophylaxis with Isavuconazole or Posaconazole Protects Immunosuppressed Mice from Pulmonary Mucormycosis

We assessed prophylactic or continuous therapy of isavuconazole, posaconazole, or voriconazole in treating pulmonary murine mucormycosis. In the prophylaxis studies, only isavuconazole treatment resulted in significantly improved survival and lowered tissue fungal burden of immunosuppressed mice infected with Rhizopus delemar. In the continuous treatment studies, isavuconazole and posaconazole, but not voriconazole, equally prolonged survival time and lowered tissue fungal burden compared to placebo-treated mice. These results support the use of isavuconazole and posaconazole in prophylaxis treatment.

Mucormycosis: a new concern in the transplant ward?

PURPOSE OF REVIEW

This study focuses on the epidemiology and management of mucormycosis in hematopoietic stem cell transplant patients, a life-threatening mold infection whose incidence has increased over the past decades.

RECENT FINDINGS

Mucormycosis may occur in hematopoietic stem cell transplant recipients with severe graft-versus-host disease, steroids, neutropenia, iron overload, diabetes, and malnutrition, or those who received antifungals not active against Mucorales. Its incidence in allogeneic hematopoietic stem cell transplant is around 0.3%. As Mucorales are not susceptible to voriconazole and candins, and as mucormycosis often mimics aspergillosis, it is extremely important to have a precise diagnostic to correctly manage the patient. The reversed halo sign on chest computed tomography has been associated to mucormycosis in neutropenic patients, but is not pathognomonic. Direct fungal identification is crucial. Molecular approaches are developed that may be extremely useful for early diagnosis.

SUMMARY

Although randomized trials are quite impossible to run, due to the rarity of the disease, the recent numerous data have allowed the elaboration of European guidelines for the management of mucormycosis. Lipid formulations of amphotericin B, and especially liposomal amphotericin B at high doses (5-10 mg/kg/day), are the standard treatment, combined with surgery and control of favoring factors. The prognosis is poor, and any delay in the initiation of therapy may impact on outcome.

Pharmacokinetics of posaconazole prophylaxis of patients with acute myeloid leukemia

Antifungal prophylaxis is routinely given to patients with hematologic malignancies at high risk for invasive fungal infections (IFI), yet breakthrough IFI may still occur. Posaconazole emerged as an excellent alternative for fungal prophylaxis in high-risk patients. There is limited data about pharmacokinetics and plasma concentrations of posaconazole when given as prophylaxis in patients with hematologic malignancies. We recruited 20 adult patients for prospective, open label trial of posaconazole given as a prophylaxis in patients with newly diagnosed acute myeloid leukemia (AML) undergoing induction chemotherapy or first salvage therapy. The median age of all patients was 65 years and received prophylaxis for a median of 38 days (range: 5-42 days).Ten patients (50%) completed 42 days on posaconazole prophylaxis. Median plasma posaconazole levels showed no statistical difference across gender, body surface area, patients developing IFI, and patients acquiring grade 3 or 4 elevation of liver enzymes. However, there was an overall trend for higher trough concentrations among patients with no IFI than those with IFI. Pharmacokinetics of posaconazole varies from patient to patient, and AML patients receiving induction chemotherapy who never develop IFI tend to have higher plasma concentrations after oral administration of posaconazole.

Fatal Breakthrough Mucormycosis in an Acute Myelogenous Leukemia Patient while on Posaconazole Prophylaxis

Posaconazole is a new oral triazole with broad-spectrum antifungal activity. Posaconazole has also shown a significant advantage of preventing invasive fungal infection compared to fluconazole or itraconazole in patients with prolonged neutropenia. Indeed, posaconazole has been commonly used for antifungal prophylaxis in patients undergoing remission induction chemotherapy for acute myelogenous leukemia or myelodysplastic syndrome. We experienced a case of fatal mucormycosis despite posaconazole prophylaxis. To our knowledge, this is the first reported case of fatal breakthrough mucormycosis in a patient receiving posaconazole prophylaxis during remission induction chemotherapy in Korea. This case demonstrated that breakthrough fungal infection can occurs in patients receiving posaconazole prophylaxis because of its limited activity against some mucorales.

Evaluation of 28 cases of mucormycosis

Mucormycosis is a rare but invasive fungal disease with high mortality. The present study aimed to retrospectively investigate the demographic characteristics, as well as the clinical, radiological and laboratory features and the results of treatment, in the patients followed in our hospital because of mucormycosis. The present study retrospectively evaluated 28 cases, which were followed in our hospital because of mucormycosis between January 2002 and July 2013. The clinical form was rhinocerebral in 27 cases (rhinoorbital in 12, nasal in 8 and rhinoorbitocerebral in 7) and disseminated in one case. With regard to predisposing factors, diabetes mellitus (n = 20), haematological malignancy (n = 6) and chronic renal insufficiency (n = 5) were the leading concomitant diseases. Seventeen (61%) of 28 cases showed atypical clinical picture. With regard to the therapeutic outcomes; it was found that 14 (50%) cases died and six cases recovered with sequel. Today, when particularly the prevalence of immunosuppressive diseases and conditions are gradually increasing, the incidence of mucormycosis is also increased. Considering that the majority of our cases had atypical clinical involvement and complications, being familiar with the characteristics of this disease could be life-saving together with early diagnosis and treatment.

Infectious complications of stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) is an accepted treatment for a variety of hematologic malignancies. The profound immunosuppression these patients experience adversely affects their risk of infection. This risk is much higher than in the general population and requires aggressive diagnostic and therapeutic interventions. The chapter will outline the major infections after HSCT.

Diagnosis and treatment of mucormycosis in patients with hematological malignancies: guidelines from the 3rd European Conference on Infections in Leukemia (ECIL 3)

Mucormycosis is an emerging cause of infectious morbidity and mortality in patients with hematologic malignancies. However, there are no recommendations to guide diagnosis and management. The European Conference on Infections in Leukemia assigned experts in hematology and infectious diseases to develop evidence-based recommendations for the diagnosis and treatment of mucormycosis. The guidelines were developed using the evidence criteria set forth by the American Infectious Diseases Society and the key recommendations are summarized here. In the absence of validated biomarkers, the diagnosis of mucormycosis relies on histology and/or detection of the organism by culture from involved sites with identification of the isolate at the species level (no grading). Antifungal chemotherapy, control of the underlying predisposing condition, and surgery are the cornerstones of management (level A II). Options for first-line chemotherapy of mucormycosis include liposomal amphotericin B and amphotericin B lipid complex (level B II). Posaconazole and combination therapy of liposomal amphotericin B or amphotericin B lipid complex with caspofungin are the options for second line-treatment (level B II). Surgery is recommended for rhinocerebral and skin and soft tissue disease (level A II). Reversal of underlying risk factors (diabetes control, reversal of neutropenia, discontinuation/taper of glucocorticosteroids, reduction of immunosuppressants, discontinuation of deferroxamine) is important in the treatment of mucormycosis (level A II). The duration of antifungal chemotherapy is not defined but guided by the resolution of all associated symptoms and findings (no grading). Maintenance therapy/secondary prophylaxis must be considered in persistently immunocompromised patients (no grading).

Posaconazole for the treatment of mucormycosis

Posaconazole (PCZ) is an orally administered, extended-spectrum triazole antifungal agent with activity against the Mucorales. This article describes the clinical and laboratory data supporting its use against this rare group of pathogens. To date, PCZ has been mostly used for salvage therapy and at present there is no strong published clinical evidence to support its role as a single agent in the treatment of mucormycosis. Further studies are required to explore its role as a single agent and in combination therapy for the management of these infections.

Recent advances in the treatment of mucormycosis

In recent years, substantial advances have been achieved in the treatment of mucormycosis. It is now clear that early initiation of therapy results in substantially better outcomes, underscoring the need to maintain a high index of suspicion and aggressively biopsy potential lesions. Increasing data support the need for surgical excision of infected and/or necrosed tissue whenever feasible. Based on their superior safety and efficacy, lipid formulations of amphotericin B have become the standard treatment for mucormycosis. Posaconazole may be useful as salvage therapy, but cannot be recommended as primary therapy for mucormycosis based on available data. Pre-clinical and limited retrospective clinical data suggest that combination therapy with lipid formulations of amphotericin and an echinocandin improves survival during mucormycosis. A definitive trial is needed to confirm these results. The use of the iron chelator, deferasirox, as adjunctive therapy also improved outcomes in animal models of mucormycosis. However, its efficacy was not confirmed in a recent, phase 2 clinical trial. Additional study is required of the potential for abrogation of iron acquisition as adjunctive treatment of mucormycosis. Combination polyene-posaconazole therapy was of no benefit in pre-clinical studies. Adjunctive therapy with recombinant cytokines, hyperbaric oxygen, and/or granulocyte transfusions can be considered in selected patients. Large-scale, prospective, randomized clinical trials are needed to define optimal management strategies for mucormycosis.

Mucormycosis: its contemporary face and management strategies

Several countries have seen rising frequencies of mucormycosis among patients with haematological disorders, malignancies, or diabetes mellitus, and among transplant recipients. Growing numbers of immunocompromised hosts, widespread use of antifungal agents inactive against mucormycosis, or other unidentified factors, could be contributing to this situation. The predominant clinical manifestations of mucormycosis vary from host to host. Additionally, risk factors specific to different subgroups have been identified, such as leukaemia, allogeneic haemopoietic stem-cell transplant, voriconazole prophylaxis, diabetes, and malnutrition. We summarise the current state of knowledge of characteristics and risk factors and discuss topical developments in therapeutic methods and strategies in the management of mucormycosis.

Molds: hyalohyphomycosis, phaeohyphomycosis, and zygomycosis

Emerging fungi previously thought to be nonpathogenic are now recognized as playing a significant role in the increased incidence of invasive fungal disease. This change in the epidemiology of invasive fungal infections (IFIs) has occurred in the era of aggressive new therapies for hematopoietic stem cell transplantation and other malignancies that lead to profound immunosuppression for longer durations and has extended the survival of these critically ill patients. The significant morbidity and mortality associated with these infections is not only related to the host populations but to delayed recognition and diagnosis and high rates of resistance in some of these emerging pathogens to standard antifungal therapies.

Fatal rhizopus pneumonia in allogeneic stem cell transplant patients despite posaconazole prophylaxis: two cases and review of the literature

Posaconazole is a triazole with broad spectrum of activity against multiple fungi including members of the fungal order Mucorales. This activity has been shown both in clinical and in vitro studies, which are critically reviewed here. It has become very popular in prophylaxis in acute myelogenous leukemia (AML) induction and in the graft-versus-host disease (GVHD) settings after 2 recent prospective trials that showed advantage of posaconazole prophylaxis compared to fluconazole or itraconazole. In this report, 2 patients are presented, in whom, despite posaconazole prophylaxis, invasive and ultimately fatal Rhizopus pulmonary infections developed. These cases are similar to a previously reported case of Rhizopus infection in a stem cell transplant recipient who also received posaconazole, indicating a potential newly recognized pattern of breakthrough infections in patients receiving posaconazole prophylaxis.