Mucormycosis among Children with Hematological Malignancies is Associated with High-Risk Acute Lymphoblastic Leukemia and is Often Salvageable

Mucormycosis has emerged as an increasingly important infection in patients with hematological malignancies, and is associated with considerable morbidity and mortality. However, contemporary data concerning epidemiology and outcome in children is lacking. Here we report a nationwide multicenter study of mucormycosis among children with hematological malignancies. Between the years 2004-2017, 1136 Israeli children aged ≤18 years with acute leukemias (acute lymphoblastic leukemia (ALL)-941; acute myeloid leukemia (AML)-195) were prospectively enrolled on a centralized clinical registry. Fungal infections, including mucormycosis, were prospectively and retrospectively captured. In addition, all 7 pediatric hematology centers were required to search hospital medical records, microbiology databases, and pathology information systems for cases of mucormycosis. Following central revision, 39 cases of mucormycosis were identified. Patient characteristics: Median age at mucor diagnosis: 13.5 years. Underlying diseases: ALL-27, AML-9, other-3. In 24 patients mucormycosis occurred during frontline therapy of their disease, and in 15 patients at relapse. Known risk factors included stem cell transplantation (SCT)-13 (33%), severe neutropenia-33 (85%) and corticosteroids-26 (67%). Among 20 patients on frontline ALL therapy, mucormycosis was diagnosed during induction in 13 cases, reinduction-6 cases, consolidation-1 case. Twenty-five patients with mucormycosis were enrolled on the national acute leukemia registry (not included: other malignancies, non-Israeli patients, relapsed leukemia with primary diagnosis preceding registry initiation, secondary AML). An analysis of registry cases demonstrated that the incidence of mucormycosis did not significantly increase during the study period. There was no seasonal clustering. Mucormycosis was significantly more common among patients ≥10 years old (4% vs 1%, p=0.004). Among patients on frontline treatment, mucormycosis was significantly more common in high-risk (HR) ALL patients (6%) than in non-HR (1%) or AML (1%) patients (p=0.001). Mucormycosis: Patterns of infection included sinusitis/sino-orbital-16 (41%), rhinocerebral-8 (21%), pulmonary-3 (8%), mandibular -4 (10%), gastrointestinal-1, cutaneous-1, otomastoiditis-1, disseminated-6 (15%). The majority (46%) were caused by Rhizopus spp. EORTC criteria: proven-30, probable-7, possible-2 (pathognomonic radiological findings and molecular diagnosis). Treatment: Nineteen patients were treated with amphotericin B formulations only and 19 received combined antifungal treatment. Nine patients received step-down treatment with posaconazole/ isavuconazole. In addition, 33 patients underwent surgical interventions, 26 underwent 2 procedures or more (range 2-14). Median time from presentation to antifungal treatment-3 days. Outcome: Twenty-one patients died, 15 of mucormycosis, 3 of other toxicities, 3 of leukemia. Factors significantly associated with mortality from mucormycosis were preceding SCT (p=0.01), less than 2 surgical interventions (p=0.0003) and relapsed disease (p=0.006). Eight-year OS of the whole cohort, those on frontline therapy and relapsed patients was 42% (±21%), 70%(±13%), 13%(±66%), respectively. Eight-year cumulative incidence of death from mucormycosis (CIDM) in those subgroups was 40%(±8), 21%(±8), 67% (±13), respectively. To our knowledge, this is the largest population-based study of mucormycosis in children with hematological malignancies. Our study demonstrates that mucormycosis is an age-dependent toxicity, significantly more common in patients ≥10 years of age. A striking finding was the high incidence of mucormycosis among patients on frontline high-risk ALL therapy, a fact which may reflect the increasing intensity of childhood ALL treatment. In a cohort of 24 patients who developed mucormycosis on frontline therapy, including 2 patients with AML and 13 with HR-ALL, 8y-OS was 70% and 8y-CIDM was 21%.The majority of patients in this cohort were salvageable through control of underlying disease, rapid instigation of antifungal treatment, and surgical debridement procedures, albeit in some cases at a price of mutilation and long-term sequelae. Future research should focus on the complex interactions between fungi and host, and on developing novel therapeutic strategies. Figure. Figure. No relevant conflicts of interest to declare.