Successful Long-Term Use of Isavuconazole in a Tacrolimus-Treated Japanese Kidney Transplant Recipient With Disseminated Cryptococcosis and Probable Invasive Aspergillosis

Disseminated cryptococcosis, particularly cryptococcal meningitis, remains a severe fungal infection with high mortality in immunocompromised patients and usually requires prolonged azole therapy. In kidney transplant recipients receiving tacrolimus (TAC), careful management of drug-drug interactions via CYP3A is essential to maintain stable blood concentrations. We report the case of a 44-year-old man with a history of focal segmental glomerulosclerosis who had undergone a living-donor kidney transplant three years earlier. He was receiving immunosuppressive therapy with TAC, mycophenolate mofetil, and methylprednisolone. The patient developed cryptococcal meningitis and skin and soft tissue infection due to <i>Cryptococcus neoformans</i>, together with probable invasive aspergillosis of the paranasal sinuses. He received induction therapy with liposomal amphotericin B and flucytosine for approximately 10 weeks, but persistent intracranial hypertension required placement of a ventriculoperitoneal shunt. Consolidation and maintenance therapy with isavuconazole (ISCZ) was then initiated and has been continued successfully for more than 12 months, without adverse events and with stable TAC concentrations. At the time of writing, the treatment duration has exceeded 365 days, and he remains under outpatient management with no signs of recurrence. To our knowledge, reports describing more than 12 months of ISCZ therapy for cryptococcal infection are limited. This case highlights its potential as a maintenance option in transplant recipients, particularly when fluconazole or voriconazole are not suitable due to drug-drug interactions with TAC.