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Background Post hematopoietic cell transplantation (HCT) autoimmune cytopenia (AIC) is a potentially life-threatening complication, but studies focusing on large cohorts of patients transplanted for primary immunodeficiency are lacking. Objectives This study sought to determine the incidence, risk factors, and outcomes of post-HCT AIC and B-lymphocyte function following rituximab. Methods We retrospectively studied 502 children with primary immunodeficiency who were transplanted at our center between 1987 and 2018. Results Thirty-six patients (9%) developed post-HCT AIC, with a median onset of 6.5 months post-HCT. On univariate analysis, pre-HCT AIC, mismatched donor, alemtuzumab, anti-thymocyte antiglobulin, and acute and chronic graft versus host disease were significantly associated with post-HCT AIC. After multivariate analysis, alemtuzumab (subdistribution hazard ratio, 9.0; 95% CI, 1.50-54.0; P = .02) was independently associated with post-HCT AIC. Corticosteroid and high-dose intravenous immunoglobulin achieved remission in 50% (n = 18), additional rituximab led to remission in 25% (n = 9), and the remaining 25% were treated with a combination of various modalities including sirolimus (n = 5), bortezomib (n = 3), mycophenolate mofetil (n = 2), splenectomy (n = 2), and second HCT (n = 3). The mortality of post-HCT AIC reduced from 25% (4 of 16) prior to 2011 to 5% (1 of 20) after 2011. The median follow-up of 5.8 years (range, 0.4 to 29.1 years) showed that 26 of 30 survivors (87%) were in complete remission, and 4 were in remission with ongoing sirolimus and low-dose steroids. Of the 17 who received rituximab, 7 had B-lymphocyte recovery, 5 had persistent low B-lymphocyte count and remained on intravenous immunoglobulin replacement, 2 had second HCT, and 3 died. Conclusions The frequency of post HCT AIC in our cohort was 9%, and the most significant risk factors for its occurrence were the presence of graft versus host disease and the use of alemtuzumab.

Summary Background Faecal shedding of adenovirus following allogeneic haematopoietic stem-cell transplantation (HSCT) is an early sign of loss of immune control over adenovirus, but there is no consensus on the role of monitoring of faecal adenoviral load by serial testing. We investigated whether serial faecal PCR monitoring could predict the risk of adenoviraemia and survival outcomes after HSCT. Methods We did a retrospective cohort study at the Royal Manchester Children's Hospital, Manchester, UK, of patients who had received their first allogeneic HSCT between Feb 1, 2003, and Sept 1, 2016, and adenovirus infection recorded in their medical records. We excluded patients who had received second or third transplants or autologous HSCT transplants. We obtained characteristics of patients and transplants, including mortality and adenoviral reactivation, from medical records and the hospital database. All patients had blood samples tested weekly for adenovirus by PCR until immunosuppression was stopped and CD3 T-cell count recovered to greater than 0·3 × 10 9 /L. Faecal PCR was done before transplantation in all patients, and after transplantation in patients who had diarrhoea, at the onset of symptoms and weekly thereafter until diarrhoea resolved. We analysed all samples available before and after HSCT. We did subgroup analyses for patients undergoing HSCT for cancer versus non-malignant conditions. We also assessed whether 5 log 10 copies per g faeces was a suitable predictive threshold for adenoviraemia. Findings We included 341 patients who had undergone a first allogeneic HSCT (median age 4·6 years, IQR 1·5–8·0, range 0–20·0). After HSCT, PCR was done in 4116 faecal samples from 293 (86%) patients who had diarrhoea and in 10 649 blood samples from 341 patients. Follow-up ended on July 14, 2017. 173 (59%) of 293 patients had adenovirus in faecal samples and 63 (18%) of 341 had adenovirus in blood samples. Maximum faecal viral load before adenoviraemia correlated significantly with maximum blood viral load ( r =0·51, 95% CI 0·38–0·61, p 10 copies per g faeces was predictive of adenoviraemia (odds ratio 10·2, 95% CI 4·9–21·6, p vs 7·8%, 3·8–13·7 in those with positive faeces only), but was significantly increased in patients who developed adenoviraemia (27·0%, 95% CI 16·7–38·4, p Interpretation We identified a threshold faecal viral load that can predict the risk of adenoviraemia. Our findings support proliferation of adenovirus in the gastrointestinal tract before viraemia develops. Faecal PCR is suitable for early detection of children and young adults at risk of adenoviraemia, and its use might help reduce non-relapse mortality in allogeneic HSCT recipients. Funding None.

Background Our centre performed the first ex-vivo T-lymphocyte depleted (TCD) haploidentical allograft in 1987 in a child with PID. Different TCD methods have been used including CAMPATH-1M TCD marrow (n=34), CD34+ selected marrow (CD34-S, n=34), CD3/CD19 TCD PBSC (n=7), and CD3-TCRαβ/CD19 TCD PBSC (αβ-TCD, n=30)). This study aimed to examine transplant outcomes according to different methods in children with PID. Methods Between Jan 1987 and Mar 2019, 105 PID patients underwent first TCD allograft and were included in the study. Thirteen patients who received gene-modified add-back T cells were excluded. The main outcomes of interest were OS, EFS and graft failure. An event was defined as death, graft failure or second procedures for slipping chimerism. Other endpoints were neutrophil engraftment, GvHD, immune reconstitution and donor chimerism. Log-rank test was used to compare OS and EFS according to TCD methods. Cumulative incidences (CI) graft failure was calculated using a competing risk analysis, considering death as a competing event. Multilevel mixed effects modelling was performed for the longitudinal analysis of immune reconstitution and CAMPATH-1M was used as a reference group. Results Donors were haploidentical donor (n=84, 83%), MUD/MFD (n=9, 9%) and MMFD/MMUD (n=8, 8%). 94% received conditioning. Thirteen (12%) patients had aGvHD, of whom 3 had grade III-IV. None had cGvHD. The cause of death changed from predominantly infection (18/25, 72%) in CAMPATH-IM and CD34-S to non-infectious causes in all 6 deaths in CD3/CD19 and αβ-TCD. Analysis by TCD methods revealed a 5-year OS of 58% (95% CI, 40-73%) for CAMPATH-1M, 68% (49-81%) for CD34-S, 69% (22-91%) for CD3/CD19 TCD and 83% (61-93%) for (αβ-TCD (p=0.24). Age was a significant predictor of OS for non-SCID PID (p=0.02). The corresponding EFS was 46% (29-62%) for CAMPATH-1M, 47% (30-62%) for CD34-S, 69% (95% CI, 22-91%) for CD3/CD19 TCD and 83% (61-93%) for αβ-TCD (p=0.04) (Fig 1B) The CI of graft failure reduced significantly, from 29% (14-61%) for CAMPATH-1M, to 19% (95%CI, 8-45%) for CD34-S, 17% (2-18%) for CD3/CD19 TCD and none had graft failure in αβ-TCD (p=0.002) (Figure 1C). CD4+ lymphocytes were significantly higher in CD34-S at months 4 (p=0.02), 5 (p=0.01), and 6 (p=0.006) post-HCT and at month 4 (p=0.04) post-HCT in αβ-TCD when compared to CAMPATH-1M (Fig 1D). The median donor myeloid chimerism at last follow-up was higher in newer TCD; 100% (range, 0-100%) for αβ-TCD, 93% (0-100%) for CD3/CD 19 depletion, 6% (0 -49%) for CD34-S, 20% (0-100%) for CAMPATH-1M (p Conclusions Outcomes after CD3+TCR αβ/CD19+ depletion are superior to previously used TCD methods. In an experienced centre it is a safe alternative procedure and enables a wide spectrum of PID to be transplanted. The result has led to evolution of donor hierarchy in our centre.

Introduction Studies focusing on post-HCT AIC in large cohorts of patients transplanted for primary immunodeficiency (PID) are lacking. Objectives We conducted a retrospective analysis of incidence, risk factors, outcome of post-HCT AIC in children with PID and B-cell function following rituximab treatment. Methods Between January 1987-December 2018, 502 PID patients who underwent first HCT for PID at our center were included. Cumulative incidence (CI) of post-HCT AIC was calculated using a competing risk analysis, considering death as a competing event. Fine-and-Gray test was used to identify risk factors of AIC. The selected variables: gender, age at HCT, indication for HCT (SCID versus non-SCID PID), pre-HCT AIC, donor type, donor-recipient ABO matching, stem cell source, ex-vivo T-cell depletion (TCD), stem cell doses, conditioning regimen, serotherapy, GvHD prophylaxis, acute GvHD, chronic GvHD and viraemia. B-lymphocyte immune reconstitution kinetics was compared between surviving patients with post-HCT AIC without rituximab (n=18), post-HCT treated with rituximab (n=12) and controls (n=24). Results 36 (CI, 9%) developed post-HCT AIC, with median onset at 6.5 months (2.5 months - 18.2 years). On univariate analysis, pre-HCT AIC (Fig. A), mismatched donor, alemtuzumab (Fig. B), ATG, acute GvHD (Fig. C) and chronic GvHD were significantly associated with post-HCT AIC. After multivariate analysis, alemtuzumab (p=0.02) was independently associated with post-HCT AIC. Corticosteroid and high-dose IVIg (2gm/kg) achieved remission in 50% (n=18), additional rituximab led to remission in 25% (n=9), and the remaining 25% were treated with various modalities including sirolimus (n=5), bortezomib (n=3), mycophenolate mofetil (n=2), splenectomy (n=2), and second HCT (n=3). The mortality of post-HCT AIC reduced from 25% (4/16) prior to 2011 to 5% (1/20) after 2011. The median follow-up of 5.8 years (0.4-29.1) showed that 26 of 30 survivors (87%) were in complete remission, 4 (13%) were in remission with sirolimus and low dose steroid. Of 12 survivors who were treated with rituximab, immunoglobulin substitution was discontinued in 7 (52%), and 5 (48%) required on-going IVIg replacement. The median interval between HCT and rituximab was 1.95 years (0.96-19.9) in patients who were IVIg dependent and 0.73 (0.30-2.3) in patients who were IVIg-free on last follow-up (p=0.17). B-lymphocyte immune reconstitution kinetics was significant slowly in patients with post-AIC with/without rituximab (Fig. D). Conclusions 5-year CI of post-HCT AIC in children with PID was 9% and there is risk of very late onset post-HCT AIC in patients with Artemis and RAG1 mutations, and activated PI3 delta syndrome. Alemtuzumab pk study might play a role in reducing the incidence of post-HCT AIC. Sirolimus is an effective steroid-sparing immunomodulator in refractory/frequently relapsing post-HCT AIC.