Invasive Fungal Disease in Acute Leukemia: Single Center Retrospective Study
*Corresponding author:Dr. Gowri Satyanarayana, 1161 21st Ave S. A-2200 Medical Center North Nashville, TN 37232-2582, Phone number: 615-322-2035, Fax: 615-343-6160;Email: firstname.lastname@example.org
Invasive fungal disease (IFD) is a significant cause of morbidity and mortality in patients undergoing treatment for acute leukemia. Development of IFD can delay receipt of potentially curative therapy for the underlying malignancy, including additional chemotherapy or hematopoietic cell transplant (HCT). Mortality from invasive candidiasis or aspergillosis has been shown to approach 40-50% and mortality from fusariosis or zygomycosis has been reported to exceed 70% . A large retrospective Italian study found the overall incidence of IFD to be 12.3% in patients with acute myeloid leukemia (AML) and 6.5% in patients with acute lymphoblastic leukemia (ALL) . Other investigators have reported incidences of IFD in hematologic malignancies ranging from 10.8% to 48.4% [2-6]. Historically, Candida albicans and Aspergillus were implicated in most clinically significant fungal infections [2, 7]. However, in recent years, there has been a rising incidence of IFD due to non-albicans species of Candida and mycelial fungi other than Aspergillus . This shift has been attributed to the increasing number of vulnerable hosts due to broader use of immunosuppressive agents, earlier identification of infections as a result of improved diagnostics, advances in transplantation techniques, use of novel chemotherapeutic agents, and frequent implementation of antifungal prophylaxis [3, 8, 9].
Current U.S. national guidelines recommend the use of antifungal prophylaxis in patients undergoing treatment for acute leukemia [10, 11]. The National Comprehensive Cancer Network (NCCN) recommends antifungal prophylaxis for all neutropenic patients with AML or ALL receiving chemotherapy, with continuation until resolution of neutropenia. Posaconazole is recommended for antifungal prophylaxis in patients with AML. Alternatively, use of fluconazole, voriconazole, or amphotericin B may be acceptable. Fluconazole or an echinocandin are suggested prophylactic agents in patients with ALL. The NCCN guidelines also recommend consideration of local susceptibility patterns when deciding on the appropriate prophylaxis regimen. Guidelines from the Infectious Diseases Society of America (IDSA) recommend prophylaxis against Candida in patients undergoing intensive remission-induction or salvage-induction chemotherapy for acute leukemia. Prophylaxis against Aspergillus with posaconazole is recommended in patients undergoing intensive chemotherapy for AML whose risk of invasive aspergillosis is substantial. Antifungal prophylaxis is not recommended for patients with an anticipated duration of neutropenia less than 7 days.
At our institution, fluconazole has been used for routine antifungal prophylaxis during periods of neutropenia following chemotherapy for AML or ALL. Anecdotally, there has been an increasing prevalence of invasive mold infections that are not susceptible to fluconazole. The aim of this study was to elucidate the epidemiology of IFD in this patient population and identify factors which may increase the risk of developing IFD, with the goal of determining the potential need for adjustments to the regimen used for routine antifungal prophylaxis.
Materials and Methods
This retrospective study was approved by the Human Research Protection Program Institutional Review Board at Vanderbilt University (#141331). Study data were collected and managed using REDCap electronic data capture tools hosted at Vanderbilt University .
Patients and Treatment Details
Inpatient ICD-9 codes for AML without remission (204.00) and ALL without remission (205.00) were used to identify prospective patients. Patients were included in the study if they were 18 years of age or older and admitted to Vanderbilt University Medical Center (VUMC) between July 1, 2012 and June 30, 2014 for chemotherapy for AML or ALL. Patients were excluded if they did not receive chemotherapy, received all chemotherapy outside of VUMC, received all chemotherapy prior to the start date of the study, or were assigned the incorrect diagnosis code. Each patient’s clinical course was followed until the date of last follow up, death, or admission for HCT.
Covariates and Definitions
Demographic data was collected for each patient and included age, sex, type and subtype of leukemia, significant genetic mutations associated with leukemia, underlying diabetes mellitus, date of death, and date of HCT. Data were collected for all chemotherapy sessions during the study time period. A chemotherapy session was defined as the period of time from the start date of a cycle of chemotherapy until the day prior to the start of the next chemotherapy cycle. Data collected for each chemotherapy session included chemotherapy regimen (including induction or consolidation), baseline laboratory values (including complete blood count with differential and comprehensive metabolic panel), dates of neutropenia, nadir of neutrophil count, antifungal use, results of fungal antigen tests, and outcomes including development of IFD, ICU admission, mortality, disease remission, and transplant. Neutropenia was defined as an absolute neutrophil count (ANC) less than 500. Duration of neutropenia was defined as beginning on the first day when ANC was less than 500 and ending on the day when ANC had been greater than 500 for three days. Neutropenic fever was defined as temperature ≥100.4°F during a period of neutropenia.
Patients were identified as having IFD if they met criteria for proven or probable IFD per the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycosis Study Group (EORTC/MSG) . Data were collected for each case of IFD on the causative pathogen, location of infection, method of diagnosis, and treatment.
Non-parametric continuous variables were compared using the Wilcoxon-Rank Sum and categorical variables were compared using Pearson’s chi-squared test. The cumulative incidence of developing IFD after 12 months was determined by Kaplan-Meier analysis. Pearson’s chi-squared test with Yates’ continuity correction was used for analysis of antifungal exposure. A Cox model was used to examine the association between duration of neutropenia and development of IFD. Statistical analysis was performed using R Version 3.3.1.
A total of 223 patients were included in the study, of which 179 patients (80%) had AML and 44 patients (20%) had ALL. A total of 712 chemotherapy sessions were included. Demographic data obtained for each patient is shown in Table I. In the entire cohort, the average age at the time of first chemotherapy was 56 years, 58% were male, 51% died prior to end of the study, and 21% were diabetic. There were no statistically significant differences in demographics seen between patients who developed IFD and those that did not. A trend was noted towards higher mortality in patients with IFD compared to those without IFD, but statistical significance was not reached.
Invasive fungal disease
There were 22 cases of IFD identified in 20 patients during 21 chemotherapy sessions. The overall incidence of IFD was 9%. In AML patients, the incidence was 10% and in ALL patients, the incidence was 5%. The cumulative risk of IFD development within 100 days of chemotherapy was 9% (95% CI 5-12%) and within 12 months of chemotherapy was 10% (95% CI, 6%-14%) (Figure I).
Of the 22 IFD cases, 17 were proven and 5 were probable per EORTC/MSG criteria. The causative organisms in four IFD cases were yeasts and all were non-albicans Candida. Invasive molds were identified in 17 cases of IFD. The causative organism was unable to be definitively identified in one case, but likely represented an invasive mold. The most commonly identified organism was Aspergillus fumigatus (7 cases, 5 of which were pulmonary aspergillosis). Additionally, there were 6 cases of mucormycosis and a case of blastomycosis identified (Table II).
Of the 20 patients who developed IFD, 19 (95%) had received prophylactic fluconazole during periods of neutropenia. Additionally, 12 (60%) had received voriconazole and 12 (60%) had received micafungin prior to diagnosis. There was no statistically significant difference in the use of fluconazole, voriconazole, or micafungin between those patients who developed IFD and those that did not. There was increased use of voriconazole in patients who developed IFD which approached statistical significance (p = 0.057).
Risk Factors for IFD
Several factors were noted to be associated with the development of IFD (Table III). IFD was seen more frequently during administration of induction chemotherapy than consolidation chemotherapy. IFD was more common in patients who developed neutropenic fever, received growth colony stimulating factor (G-CSF) analogs, developed mucositis, or required an ICU stay. Of the chemotherapy sessions in which IFD was diagnosed, 24% included the receipt of CLAG-M (cladribine, cytarabine, filgrastim, and mitoxantrone), while CLAG-M was used in only 4% of chemotherapy sessions in patients without IFD (p < 0.001).
A Cox model analysis was used to examine the association between duration of neutropenia and risk of IFD development. The non-linear effect of duration of neutropenia was addressed by using restricted cubic spline (Figure II). The analysis showed a significant association of non-linear trend (p = 0.02). The peak relative hazard occurred at around 29 days of neutropenia with a subsequent plateau. The mean duration of neutropenia prior to diagnosis was 26 days in patients who developed IFD. In patients who did not develop IFD, the mean duration of neutropenia was 20 days (p = 0.001).
The overall incidence of IFD in our cohort of patients with acute leukemia was 9%, with an incidence of 10% in AML patients and 5% in ALL patients. These results are similar to the findings of Pagano et al  and Hammond et al [2, 4] who reported IFD incidences among acute leukemia patients at their institutions to be 10.8% and 13.4% respectively. The incidence of IFD in our cohort was lower than that reported by several other groups, including 48.4% in a cohort of AML patients , 31% found on autopsy of patients with hematologic malignancies (the majority of which had leukemia) , and 35% in non-M3 AML patients . These studies had variable use of antifungal prophylaxis, ranging from none [4, 5, 6], to minimal , to routine use of fluconazole or itraconazole . Ninety-five percent of patients who developed IFD in our cohort had received fluconazole prophylaxis.
We found an association between duration of neutropenia and risk of developing IFD. This is consistent with prior studies where the number of days of neutropenia was shown to be associated with IFD development within the first 100 days after induction chemotherapy . Neutropenia lasting longer than 29 days placed patients at greatest risk for IFD in our study. Patients who received CLAG-M chemotherapy also appeared to be at higher risk of developing IFD, likely attributable to the prolonged neutropenia caused by this cytotoxic regimen. Several other clinical characteristics were found to be associated with increased risk of developing IFD, including receipt of induction chemotherapy, development of neutropenic fever, receipt of G-CSF analogs, development of mucositis, and admission to an ICU. It is possible that these factors represent confounding variables indicating patients with more active malignancy and/or greater immunosuppression related to their chemotherapy. However, these variables could aid in identifying patients at higher risk for development of IFD who would benefit most from use of a broader agent for antifungal prophylaxis, such as posaconazole.
Strengths of our study include a close analysis of each individual chemotherapy session, which led to capturing a large amount of data for each patient. There was also broad use of fluconazole for antifungal prophylaxis in our cohort (91% of all patients and 95% of patients who developed IFD) which provided homogeneity. Weaknesses of our study include the retrospective nature, inclusion of a single center, and short time period. Additionally, there were a small number of IFD cases identified which prohibited a multivariate analysis.
Current recommendations from the NCCN and IDSA [10, 11] are based on the results of randomized controlled trials that have indicated the superiority of using posaconazole as IFD prophylaxis [1, 14]. However, concerns have been raised about the safety profile of posaconazole. A 2007 multicenter randomized controlled trial of 304 patients compared posaconazole to fluconazole or itraconazole as antifungal prophylaxis . While posaconazole was shown to prevent IFD more effectively, there was a significantly greater incidence of adverse drug events probably or possibly related to therapy in the posaconazole arm of the study. Most events were cardiac or hepatic toxicity, including a patient who developed torsades de pointes and a patient who developed hepatic failure. There was no difference in all-cause mortality at 100 days. Additionally, a retrospective study of 130 patients investigating prophylactic antifungal use in a single tertiary-care center saw superior effectiveness of posaconazole versus fluconazole . This study also showed similar all-cause mortality at 100 days. Other concerns regarding the use of posaconazole as routine antifungal prophylaxis include the high cost of the drug as well as breakthrough resistant fungal infections in patients receiving posaconazole prophylaxis [9, 16, 17].
Use of posaconazole as antifungal prophylaxis may be reasonable in higher risk patients at our institution, namely patients with AML undergoing induction chemotherapy or receiving CLAG-M. Routine prophylaxis with fluconazole appears to be adequate for patients with ALL and patients with AML undergoing consolidation chemotherapy. Use of posaconazole may be warranted in these patients if they are neutropenic for greater than 29 days. Future studies will be needed to evaluate the shift in IFD pathogens with the use of anti-mold agents, such as posaconazole, as prophylaxis.
We would like to thank Dr. Steve Dummer for critically reviewing the study proposal and Dr. Lora Thomas for statistical support for poster preparation. We would like to thank Mahsa Talbott, PharmD for her contribution to the study design.
Study concept and design: JE, SS, GS. Acquisition of data: JE, ST, MF, GS. Analysis and interpretation of data: JS, ST, HC, GS. Drafting of the manuscript: JE, ST, HC, MF, GS. Critical revision of the manuscript for important intellectual content: JE, ST, HC, MF, GS. JE, ST, HC, MF, SS, and GS provided final approval to submit this version of the manuscript and have agreed to be accountable for all aspects of the work.
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