Successful allogeneic hematopoietic stem cell transplantation for AML with pulmonary mucormycosis under isavuconazole

Invasive pulmonary mucormycosis (IPM) is a rare fungal infection, which can be fatal in immunocompromised patients, particularly in those with hematological malignancies. Although liposomal amphotericin B (≥5 mg/kg) administration following complete surgical resection is recommended, many cases remain incurable. A 70-year-old man with FLT3-ITD mutated acute myeloid leukemia achieved complete remission after the second induction therapy with gilteritinib. During the period of myelosuppression following the initial treatment, he developed IPM in the left lung. Bronchoscopy revealed Lichtheimia corymbifera. Surgical resection was initially not possible because of pleural adhesions due to inflammation caused by mucormycosis. Based on the isavuconazole (ISCZ) treatment, we performed allogeneic hematopoietic stem cell transplantation (allo-HCT), resulting in successful engraftment without IPM progression. Complete surgical resection was performed 1 year after allo-HCT. However, mucormycosis relapsed in the contralateral lung 2 months after ISCZ discontinuation. Re-treatment with ISCZ was effective. This case suggested that allo-HCT could be successfully performed in selected patients with unresectable IPM when effective antifungal therapy is administered. Early neutrophil recovery and close clinical monitoring are essential. To the best of our knowledge, this is the first reported case of ISCZ treatment in an allo-HCT patient with unresectable IPM. ISCZ could be a safe and effective anti-Mucorales therapy in the allo-HCT setting.