Revealing the Unseen: Next-Generation Sequencing for Early Detection of Drug-Resistant Cytomegalovirus Variants Upon Letermovir Prophylaxis Failure

Abstract

Abstract In recipients of allogeneic hematopoietic cell transplant, prophylactic management strategies are essential for preventing cytomegalovirus (CMV) reactivation and associated disease. We report on a 63-year-old male patient with a D−/R+ CMV serostatus, who showed ongoing low-level CMV replication after hematopoietic cell transplant despite receiving letermovir prophylaxis. Sanger sequencing failed to detect drug resistance mutations (DRMs) until CMV pneumonitis developed, revealing a UL56-C325R DRM linked to high-level letermovir resistance. Retrospective analysis with next-generation sequencing revealed the DRM at a low frequency of 6% two weeks prior to detection by Sanger sequencing. This study highlights the importance of advanced next-generation sequencing methods for early detection of CMV DRMs, allowing for faster adjustments in antiviral treatment strategies.