The clinical application of plasma Kaposi sarcoma herpesvirus viral load as a tumour biomarker: results from 704 patients

Objectives The aim of the study was to evaluate the role of plasma Kaposi sarcoma herpesvirus (KSHV) as a diagnostic and prognostic biomarker in people living with HIV (PLWH) and diagnosed with KSHV-associated diseases. Methods Using quantitative nested polymerase chain reaction (PCR) targeting the open reading frame-26 gene of KSHV, plasma levels of KSHV were measured in consecutive PLWH with KSHV-associated diseases or as part of the investigation of lymphadenopathy. Results Plasma KSHV assays were performed on samples from 684 PLWH and 20 HIV-seronegative people with KSHV-associated malignancies. In PLWH, plasma KSHV was detected in 39% of those with KS, 99% of those with multicentric Castleman disease (MCD), 9% of those with non-Hodgkin lymphoma (NHL), 2% of those with non-AIDS-defining malignancies and 0% of those with nonmalignant lymphadenopathy. There was no significant difference in plasma KSHV viral load among those with KS, MCD and KSHV-associated NHL. The 5-year overall survival rate from KS diagnosis of 335 PLWH was 95.2% (95% confidence interval 92.6-97.8%). Plasma KSHV viraemia did not predict overall survival in those with KS (P = 0.73), nor when those with T0 stage KS (P = 0.52) or T1 stage KS (P = 0.62) were analysed separately. Conclusions Measuring the plasma levels of KSHV as a biomarker in KSHV-associated disease has a very limited value in either diagnosis or prognostication. The only potential role of clinical value is the suggestion that an undetectable plasma KSHV excludes a diagnosis of MCD in PLWH.