Sanjeet Dadwal

Epidemiology and treatment approaches in management of invasive fungal infections

Over the past 20 years, the number of invasive fungal infections has continued to persist, due primarily to the increased numbers of patients subjected to severe immunosuppression. Despite the development of more active, less toxic antifungal agents and the standard use of antifungal prophylaxis, invasive fungal infections (especially invasive mold infections) continue to be a significant factor in hematopoietic cell and solid organ transplantation outcomes, resulting in high mortality rates. Since the use of fluconazole as standard prophylaxis in the hematopoietic cell transplantation setting, invasive candidiasis has come under control, but no mold-active antifungal agent (except for posaconazole in the setting of acute myelogenous leukemia and myelodysplastic syndrome) has been shown to improve the survival rate over fluconazole. With the advent of new azole and echinocandin agents, we have seen the emergence of more azole-resistant and echinocandin-resistant fungi. The recent increase in zygomycosis seen in the hematopoietic cell transplantation setting may be due to the increased use of voriconazole. This has implications for the empiric approach to pulmonary invasive mold infections when zygomycosis cannot be ruled out. It is imperative that an amphotericin B product, an antifungal that has never developed resistance in over 50 years, be initiated. The clinical presentations of invasive mold infections and invasive candidiasis can be nonspecific and the diagnostic tests insensitive, so a high index of suspicion and immediate initiation of empiric therapy is required. Unfortunately, our currently available serologic tests do not predict infection ahead of disease, and, therefore cannot be used to initiate “preemptive” therapy. Also, the Aspergillus galactomannan test gives a false negative result in patients receiving antimold prophylaxis, ie, virtually all of our patients with hematologic malignancy and hematopoietic cell transplant recipients. We may eventually be able to select patients at highest risk for invasive fungal infections for prophylaxis by genetic testing. However, with our current armamentarium of antifungal agents and widespread use of prophylaxis in high-risk groups (hematologic malignancy, hematopoietic cell transplantation), we continue to see high incidence and mortality rates, and our future hope lies in reversing the immunosuppression or augmenting the immune system of these severely immunocompromised hosts by developing and utilizing immunotherapy, immunoprophylaxis, and vaccines.

A phase 1/2 study of an adjuvanted varicella-zoster virus subunit vaccine in autologous hematopoietic cell transplant recipients

Recombinant herpes zoster (HZ) vaccines may be an alternative to the live-attenuated HZ vaccine for immunocompromised individuals. This was a phase 1/2, randomized, observer-blind, placebo-controlled study in adults with multiple myeloma, non-Hodgkin lymphoma (B- or T-cell), Hodgkin lymphoma, or acute myeloid leukemia who had undergone autologous hematopoietic stem-cell transplant 50 to 70 days earlier. Subjects (N = 121) were randomized 1:1:1:1 to receive (at months 0, 1, 3) three doses of 50 μg varicella-zoster virus glycoprotein E (gE) adjuvanted with AS01B, 3 doses of gE adjuvanted with AS01E, 1 dose of saline followed by 2 doses of gE/AS01B, or 3 doses of saline. One month after the last dose (6 months after transplant), frequencies of CD4(+) T cells expressing ≥2 activation markers after induction with gE and anti-gE antibody concentrations were higher with all gE/AS01 regimens than with saline. Both responses persisted up to 1 year in subjects vaccinated with gE/AS01. Immune responses were higher in the gE/AS01B 3-dose group than in the gE/AS01B 2-dose group but not higher than in the gE/AS01E 3-dose group. One serious adverse event (pneumonia) was considered vaccine related. Both formulations and both schedules were immunogenic and well tolerated in this population. This study was registered at www.clinicaltrials.gov as #NCT00920218.

Letermovir Prophylaxis for Cytomegalovirus in Hematopoietic-Cell Transplantation

Background Cytomegalovirus (CMV) infection remains a common complication after allogeneic hematopoietic‐cell transplantation. Letermovir is an antiviral drug that inhibits the CMV–terminase complex. Methods In this phase 3, double‐blind trial, we randomly assigned CMV‐seropositive transplant recipients, 18 years of age or older, in a 2:1 ratio to receive letermovir or placebo, administered orally or intravenously, through week 14 after transplantation; randomization was stratified according to trial site and CMV disease risk. Letermovir was administered at a dose of 480 mg per day (or 240 mg per day in patients taking cyclosporine). Patients in whom clinically significant CMV infection (CMV disease or CMV viremia leading to preemptive treatment) developed discontinued the trial regimen and received anti‐CMV treatment. The primary end point was the proportion of patients, among patients without detectable CMV DNA at randomization, who had clinically significant CMV infection through week 24 after transplantation. Patients who discontinued the trial or had missing end‐point data at week 24 were imputed as having a primary end‐point event. Patients were followed through week 48 after transplantation. Results From June 2014 to March 2016, a total of 565 patients underwent randomization and received letermovir or placebo beginning a median of 9 days after transplantation. Among 495 patients with undetectable CMV DNA at randomization, fewer patients in the letermovir group than in the placebo group had clinically significant CMV infection or were imputed as having a primary end‐point event by week 24 after transplantation (122 of 325 patients [37.5%] vs. 103 of 170 [60.6%], P<0.001). The frequency and severity of adverse events were similar in the two groups overall. Vomiting was reported in 18.5% of the patients who received letermovir and in 13.5% of those who received placebo; edema in 14.5% and 9.4%, respectively; and atrial fibrillation or flutter in 4.6% and 1.0%, respectively. The rates of myelotoxic and nephrotoxic events were similar in the letermovir group and the placebo group. All‐cause mortality at week 48 after transplantation was 20.9% among letermovir recipients and 25.5% among placebo recipients. Conclusions Letermovir prophylaxis resulted in a significantly lower risk of clinically significant CMV infection than placebo. Adverse events with letermovir were mainly of low grade. (Funded by Merck; ClinicalTrials.gov number, NCT02137772; EudraCT number, 2013‐003831‐31.)

Voriconazole Serum Concentrations in Obese and Overweight Immunocompromised Patients: A Retrospective Review

To evaluate the relationship between voriconazole dose and corresponding serum concentrations in obese and overweight immunocompromised patients.

MVA vaccine encoding CMV antigens safely induces durable expansion of CMV-specific T-cells in healthy adults

Attenuated poxvirus modified vaccinia Ankara (MVA) is a useful viral-based vaccine for clinical investigation, because of its excellent safety profile and property of inducing potent immune responses against recombinant (r) antigens. We developed Triplex by constructing an rMVA encoding 3 immunodominant cytomegalovirus (CMV) antigens, which stimulates a host antiviral response: UL83 (pp65), UL123 (IE1-exon4), and UL122 (IE2-exon5). We completed the first clinical evaluation of the Triplex vaccine in 24 healthy adults, with or without immunity to CMV and vaccinia virus (previous DryVax smallpox vaccination). Three escalating dose levels (DL) were administered IM in 8 subjects/DL, with an identical booster injection 28 days later and 1-year follow-up. Vaccinations at all DL were safe with no dose-limiting toxicities. No vaccine-related serious adverse events were documented. Local and systemic reactogenicity was transient and self-limiting. Robust, functional, and durable Triplex-driven expansions of CMV-specific T cells were detected by measuring T-cell surface levels of 4-1BB (CD137), binding to CMV-specific HLA multimers, and interferon-γ production. Marked and durable CMV-specific T-cell responses were also detected in Triplex-vaccinated CMV-seronegatives, and in DryVax-vaccinated subjects. Long-lived memory effector phenotype, associated with viral control during CMV primary infection, was predominantly found on the membrane of CMV-specific and functional T cells, whereas off-target vaccine responses activating memory T cells from the related herpesvirus Epstein-Barr virus remained undetectable. Combined safety and immunogenicity results of MVA in allogeneic hematopoietic stem cell transplant (HCT) recipients and Triplex in healthy adults motivated the initiation of a placebo-controlled multicenter trial of Triplex in HCT patients. This trial was registered at www.clinicaltrials.gov as #NCT02506933.

Impact of pretransplant serum ferritin level on risk of invasive mold infection after allogeneic hematopoietic stem cell transplantation.

Invasive mold infections (IMI) are life‐threatening complications of allogeneic hematopoietic stem cell transplantation (HSCT) and are mostly caused by Aspergillus species and Mucorales. We examined whether elevated serum ferritin prior to HSCT was associated with increased risk of IMI after allogeneic HSCT. Elevated serum ferritin was defined as values ≥1000 ng/mL. Pretransplant ferritin levels were available for 477 transplants. Nine developed IMI at day 30 and 21 had IMI at day 100 for a cumulative incidence of 1.9% and 4.4%, respectively. Among the high ferritin group, eight of 220 transplant cases (3.6%) developed an IMI within 30 d after HSCT compared with one of 257 (0.4%) in the low ferritin group (P = 0.01). Fourteen of 220 (6.4%) and seven of 257 transplant cases (2.7%) in the high and low ferritin groups, respectively, had developed an IMI by day 100 after HSCT (P = 0.07). Nine of 53 (17%) patients with grades III and IV acute GVHD and iron overload experienced IMI, when compared to three of 37 (8.1%) with high‐grade aGVHD, but no iron overload. Among patients without aGVHD, those with elevated ferritin had a 2.7% incidence of IMI compared with 0.9% for patients without elevated ferritin. There was a marginally significant difference in cumulative incidence function between high and low ferritin groups for IMI (P = 0.06). However, elevated serum ferritin (≥1000 ng/mL) was not a significant risk factor for IMI in a multivariate competing risk regression model after adjusting for aGVHD.

Approaches to the early treatment of invasive fungal infection.

Invasive fungal infections account for significant morbidity and mortality in the seriously immunocompromised host, especially those suffering from hematologic malignancies and the recipients of hematopoietic cell transplant. One of the reasons for the continuing high mortality rates due to invasive fungal infection is the delay in administering appropriate therapy. As preemptive antifungal therapy is not feasible for lack of a predictive test, early empiric therapy is currently the only approach likely to result in improvement in survival. Here, we present our approach to both invasive candidiasis and invasive mold infection. Therapy should be initiated at the first signs and symptoms of disease, utilizing knowledge of local fungal epidemiology, the patients recent antifungal agent exposure, and the diagnostic tests immediately available, to select an appropriate antifungal agent most likely to be effective against the suspected fungal species.

Effect of isavuconazole on tacrolimus and sirolimus serum concentrations in allogeneic hematopoietic stem cell transplant patients: A drug-drug interaction study

Isavuconazole, a triazole antifungal, is an inhibitor of cytochrome P450 3A4, which also metabolizes tacrolimus and sirolimus. In previous studies, isavuconazole administration increased tacrolimus and sirolimus area under the curve values by 2.3‐fold and 1.8‐fold, respectively, in healthy adults and tacrolimus concentration/dose (C/D) ratio by 1.3‐fold in solid organ transplant patients. We aimed to determine the magnitude of effect of isavuconazole administration on tacrolimus and sirolimus C/D ratios in allogeneic hematopoietic stem cell transplant (alloHSCT) patients.

A fifty-year odyssey: prospects for a cytomegalovirus vaccine in transplant and congenital infection

ABSTRACT Introduction: It has been almost fifty years since the Towne strain was used by Plotkin and collaborators as the first vaccine candidate for cytomegalovirus (CMV). While that approach showed partial efficacy, there have been a multitude of challenges to improve on the promise of a CMV vaccine. Efforts have been dichotomized into a therapeutic vaccine for patients with CMV-infected allografts, either stem cells or solid organ, and a prophylactic vaccine for congenital infection. Areas covered: This review will evaluate research prospects for a therapeutic vaccine for transplant recipients that recognizes CMV utilizing primarily T cell responses. Similarly, we will provide an extensive discussion on attempts to develop a vaccine to prevent the manifestations of congenital infection, based on eliciting a humoral anti-CMV protective response. The review will also describe newer developments that have upended the efforts toward such a vaccine through the discovery of a second pathway of CMV infection that utilizes an alternative receptor for entry using a series of antigens that have been determined to be important for prevention of infection. Expert commentary: There is a concerted effort to unify separate therapeutic and prophylactic vaccine strategies into a single delivery agent that would be effective for both transplant-related and congenital infection.

Recent advances in the molecular diagnosis of mucormycosis

ABSTRACT Introduction: Fungal infection burden related to Mucorales has been on the rise with significant associated morbidity and mortality. The major obstacle in the management has been lack of a non-invasive rapid and a reliable diagnostic test. Developing a culture-independent biomarker for the early diagnosis of mucormycosis is a major unmet need in modern mycology. Several approaches have been developed, such as immunohistochemistry (IHC) that can confirm the histopathologic diagnosis of the invasive mold infection, polymerase chain reaction (PCR) on formalin-fixed paraffin-embedded (FFPE) or fresh tissue, body fluids such as bronchoalveolar fluid (BAL), and detection directly from serum/blood. Serologic tests, matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS), metabolomics and metagenomic shotgun sequencing are other evolving technologies. Area covered: In this review paper, we report the current status of the molecular diagnostics in the diagnosis of mucormycosis: serologic tests, IHC, PCR, protein-based with MALDI-TOF, metabolomics and metagenomic sequencing. Expert commentary: This review will conclude with an expert commentary on the potential uses/challenges of the currently available tests and the future of molecular diagnostics for mucormycosis.