BI06 The rising incidence of post-transplant Kaposi sarcoma in organ transplant recipients in a single-centre cohort: should we be routinely screening?

Abstract Kaposi sarcoma (KS) in organ transplant recipients (OTRs) is usually due to reactivation of latent human herpes virus (HHV)-8 and is therefore seen mainly in patients from countries with a high seroprevalence of HHV-8. Far fewer cases are due to HHV-8 acquired post-transplant or donor-transmitted. Since mid-2023, NHS Blood-and-Transplant (NHS-BT) has screened donor HHV-8 serology. However, there are no recommendations for screening recipients or transplant candidates. In addition, more sensitive serology testing is not routinely available, and most centres rely on HHV-8 DNA assays. In this study, we describe clinicopathological features of OTR-KS diagnosed between 2018 and 2023 in our centre and highlight an urgent need for improved HHV-8 screening of high-risk patient groups. We reviewed clinicopathological features of OTR-KS diagnosed between January 2018 and January 2023. In total, 11 OTRs had biopsy-proven KS. The median age was 53 years range (36–69) and the median time from transplant to patient-reported onset of KS lesions was 7.5 months. Ten of 11 patients (91%) were born in sub-Saharan Africa. One patient was HIV positive. Cutaneous KS was present in all patients, there was lymph-node involvement in 5 of 11 patients (45%) and visceral involvement in 2 of 11 (18%). Serum HHV-8 DNA was positive in 9 of 11 patients (81%), although in 4 of 8 patients (50%) this was negative on at least one occasion; in 2 of 11 patients it was never positive. Viral loads did not clearly correlate with disease activity. No donors were HHV-8 positive where this information was available. The most common initial treatment intervention was modification of immunosuppression; mycophenolate mofetil was stopped in 10 of 10 patients and/or calcineurin inhibitors were switched to sirolimus in 8 of 10 OTRs. In 10 of 11 patients (91%) this was sufficient to control KS. Only one OTR required chemotherapy. Graft loss occurred in 4 of 11 cases (36%). One patient died shortly after return to dialysis following chemotherapy. We have previously published data on 16 cases of OTR-KS diagnosed in our centre between 1989 and 2018. The current series of 11 cases over the past 5 years represents a significant increase and is likely to reflect, in large part, the changing demographics of our patient population. We have demonstrated that diagnostic and predictive use of HHV-8 DNA testing has limitations: 6 of 11 patients (54%) had one or more negative tests despite positive HHV-8 immunohistochemistry on skin biopsy. Although NHS-BT now routinely screens all donors, our data highlight a significant need for routine recipient testing. We propose that routine pre/post-transplant screening with improved HHV-8 assays should be introduced, at least in patient populations at risk of latent HHV-8. Such screening has potential to allow optimized post-transplant management of HHV-8 positive OTRs and ultimately improve outcomes in OTR-KS.