Herpesvirus Viremia and Engraftment Status of Umbilical Cord Blood in Children Undergoing Allogeneic Hematopoietic Stem Cell Transplant
Bibliographic record
Abstract
Abstract Abstract 3021 Umbilical Cord Blood (UCB) is frequently used as a source of stem cells for children undergoing allogeneic hematopoietic stem cell transplant (HSCT) for both benign and malignant disorders. Despite algorithms using both nucleated cell numbers and HLA typing, the rate of engraftment failure remains higher than rates observed using other stem cell products. We conducted a retrospective review of our centre's experience with HSCT with UCB to evaluate the impact of herpesvirus viremia on the rate of engraftment. Children who underwent allogeneic HSCT with UCB between 06/2005 and 05/2010 inclusive were identified from the program database. Engraftment was defined as the first day of three consecutive absolute neutrophil counts of > 0.5 × 10[exp 9]/L within 42 days of UCB infusion and evidence of donor DNA on chimerism testing. Blood samples were sent for qualitative herpesvirus polymerase chain reaction (PCR) weekly (HHV-6, HHV-7, EBV, CMV, HSV or VZV). If either CMV or EBV results were positive, a quantitative assay was performed as well. Viremia was considered to have occurred if the qualitative assay became positive. Anti-viral therapy was initiated for measurable amounts of either CMV or EBV DNA or selectively for HHV-6 DNA. Eighty-one HSCT utilizing UCB were performed during this period. One child was unevaluable (NRM at day +15) so the analysis was performed using the remaining 80 patients. Thirty HSCT (37.5%) were performed for non-malignant indications and 50 (62.5%) for malignant disorders. Ninety per cent were performed using unrelated UCB; 27 were 6/6 HLA matched UCB, 42 were 5/6 HLA matches and 11 were 4/6 matches. Four children were recovering counts at day +42 but had not reached the threshold neutrophil value. They were considered as delayed engraftment rather than engraftment failure. Eleven (14%) failed to engraft. Forty-two (52.5%) of the transplants were complicated by the detection of 1 or more herpesviruses (24 for only 1 virus, 15 for 2 viruses and 3 for 3 viruses). None of gender, ABO matching, recipient CMV pre-HSCT serostatus, disease category, use of ATG or TBI in the conditioning regimen, use of methotrexate as GVHD prophylaxis or positivity for any single herpesvirus was associated with engraftment failure. Numbers of viable nucleated cells and CD34+ cells were not different between those that engrafted and those that failed to engraft. Transplants complicated by viremia of more than 1 herpesvirus had a significantly poorer engraftment rate than others (0.667 vs 0.933, P=0.007); more specifically viremia due to CMV and any other herpesvirus was associated with a worse engraftment rate than others (0.643 vs 0.921, P=0.006) (table). Notably viremia due to HHV-6 and others or EBV and others were not related to engraftment failure.PCR resultEngraftedFailed to engraftNo CMV516CMV positive185CMV alone90CMV plus: HHV-632 HHV-721 EBV22 HHV-6 & HHV-710 HHV-6 & EBV10 Conclusion: A significantly poorer engraftment rate in children undergoing HSCT using UCB was seen in those with CMV viremia in the presence of another herpesvirus. Further research is needed to define cause and effect and the therapeutic strategies to prevent it. Disclosures: No relevant conflicts of interest to declare.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".