Infection Burden of Double Stranded DNA (dsDNA) Viruses after CD34+ Selected, T-Cell Depleted (TCD) Hematopoietic Cell Transplantation (HCT) for Myeloid Malignancies at Memorial Sloan Kettering Cancer Center (MSK)

Background: Ex vivo T-cell depletion (TCD) by CD34⁺ selection has been used successfully for graft-versus-host disease prevention alleviating the need for additional pharmacologic immunosuppressants. TCD has been associated with higher rates of viral infections and cytomegalovirus (CMV) disease in particular compared to conventional (CONV) HCT. Modern methods of TCD achieve up to 5 log reduction of T-cells. At MSK, TCD HCT recipients (R) are routinely monitored for CMV, adenovirus (ADV), Epstein-Barr virus (EBV), and human herpes virus 6 (HHV6) in the blood by quantitative polymerase chain reaction (qPCR) assays. We report the incidence of viremia and end organ disease (EOD) by these viruses in TCD HCT recipients.

Methods: Retrospective review of adults with acute leukemia (AL) and myelodysplastic syndrome (MDS) patients (pts) who received TCD HCT at MSK from June 2010 –December 2014. TCD was performed by the FDA approved CliniMACS CD34⁺ reagent system (Miltenyi Biotec, Gladbach, Germany). CMV was monitored at least weekly from day 14-100 and at least every 14 days until day 180. EBV was monitored through day 180.  Monitoring for CMV and EBV was performed by the Clinical Microbiology Laboratory at MSK using Roche analyte specific reagents, and since March 2013, the Cobas Ampliprep/Cobas Taqman (CAP/CTM) CMV qPCR in plasma. Monitoring for ADV/HHV6 was performed by Viracor-IBT laboratories (Lenexa, KS). Preemptive treatment for CMV was started for ≥2 consecutive PCR >500copies/ml in whole blood or >300 IU/ml in plasma. Treatment of ADV/HHV6 viremia was at clinician's discretion. EBV post-transplant lymphoproliferative disorder (PTLD) was treated with rituximab as primary therapy. During the study, 11 pts were enrolled in CMV prevention trials of brincidofovir (BCV), and 5 pts received BCV for treatment of ADV.  EOD was scored by standard criteria. Follow up was through June 2015. The cumulative incidence (CI) was estimated for viremia at 180 days and EOD at 365 days for CMV, ADV, HHV6, and EBV. Kaplan-Meier method and log-rank test were used to compare CI between groups. P<0.05 was deemed statistically significant.

Results: Of 239 pts (median age 56.3 years, range 19.6-73.3), 161 (67%) pts had AL and 78 (33%) pts had MDS. Donors were matched-related 76 (32%), matched unrelated 116 (48%), or mismatched (related or unrelated) 47(20%); CMV R+ 148 (62%) or R- 91 (38%). CMV infection had the earliest onset post HCT at a median of 28 days (d) (IQR: 25-33), followed by HHV6 33d (25-52), ADV 71d (44-89), and EBV 85d (58-107). 188 (79%) pts had ≥1 dsDNA viral infection with 182 (76%) pts experiencing infection prior to d100. The CIs of viremia were:  CMV 42% (68% in R+ vs 0% in R-, P<0.0001), ADV 7% (10% in R+ vs 5% in R-, P=0.02), EBV 19%, and HHV6 61%. The CI of EBV and HHV6 viremia were similar between R+ and R- (P=NS). Among 100 pts with CMV viremia, 62 (62%) had dsDNA viral coinfections; including 40 (40%) with 1 coinfection, 19 (19%) with 2 coinfections, and 3 (3%) with 3 coinfections. Antiviral treatment was given to 99 pts for CMV (99% of CMV viremic pts, 67% of R+, 41% of total pts), 9pts for ADV (56% of ADV viremic pts; 4% of total), and 19 for HHV6 (16% of HHV6 viremic pts; 8% of total). In total, 42 (18%) pts developed EOD by dsDNA viruses. The most common EOD was EBV PTLD (20 pts, 9%), followed by CMV (14 pts, 7%; but 11% among CMV R+ pts), ADV (8 pts, 4%), and HHV6 (2 pts, 1%). Among 14 pts with CMV disease, 6 had pneumonitis, 5 colitis, 3 duodenitis, and 3 retinitis. Three pts had 2 sites of CMV EOD. Among 8 pts with ADV disease, 3 had colitis, 3 pneumonitis, 1 nephritis, and 1 hepatitis/colitis. Two pts had HHV6 pneumonitis.

Conclusions:  1) Viremias by dsDNA viruses occurred frequently and early post TCD HCT: 189 (79%) pts had at least 1 dsDNA viral infection, with onset of first infection before d100 in 183 (77%) pts. Around 58% of pts with CMV had coinfections with additional dsDNA virus(es). 2) Two thirds (67%) of CMV R+ and 41% of total pts received CMV antiviral treatment. 3) Overall, 18% of patients developed end organ disease by dsDNA viruses. 4) Viremias were managed effectively with intense monitoring and antiviral treatment, and rates of EOD were comparable to those of CONV HCT.  Our data highlights the need for effective strategies to reduce the total burden of dsDNA viruses after TCD HCT.

Fig 1. CIs of dsDNA viremia.

Fig 2.dsDNA viral co-infections

Fig 3. Coinfections among pts with CMV viremia