BACKGROUND: Mycophenolate mofetil (MMF) is commonly included in post-transplant cyclophosphamide (PTCy) based graft-versus-host disease (GVHD) prophylaxis after haploidentical (haplo) hematopoietic cell transplant (HCT). In the non-PTCy setting, higher MMF dose/kg has been shown to reduce rates of acute graft-versus-host disease (GVHD). When used in conjunction with PTCy, MMF is dosed at 15 mg/kg three times daily up to a maximum dose of 3 g/day. Thus, patients who weigh ≥67 kg receive 3 g/day and a variable dose/kg of MMF.
OBJECTIVE: We investigated the impact of MMF dose/kg on clinical outcomes following haploidentical PBSCT with PTCy-based GVHD prophylaxis.
METHODS: All consecutive adult patients with hematologic malignancies receiving haploidentical T cell replete peripheral blood stem cell transplant (PBSCT) with PTCy/MMF and either tacrolimus or sirolimus at the Moffitt Cancer Center or City of Hope between April 2014-August 2020 were included. For analyses, MMF dose relative to patient actual body weight (mg/kg/day), was stratified into categories of low (<29 mg/kg/day), low intermediate (29-34 mg/kg/day), high intermediate (35-41 mg/kg/day), and high (>41 mg/kg/day).
RESULTS: Three hundred eighty-six patients were included. Of these, 54 patients received low dose, 73 low intermediate, 137 high intermediate and 122 high dose MMF by relative weight exposure. In multivariate analysis, low MMF dose exposure was associated with reduced rates of relapse in comparison to the high dose group (HR=0.45, 95% CI: 0.21 to 0.94, p=0.03). This led to superior PFS among patients with low compared to high MMF dose exposure (HR=0.58, 95% CI: 0.34 to 0.99, p=0.045). MMF relative dose exposure was not associated with engraftment, GVHD, non-relapse mortality, or OS.
CONCLUSIONS: In this study of patients receiving haploidentical PBSCT with PTCy based GVHD prophylaxis, low MMF dose/kg was associated with improved rates of relapse and PFS. Future prospective studies should investigate optimal dosing strategies of MMF when given with the PTCy regimen.

BACKGROUND: High-dose post-transplant cyclophosphamide allows safe and effective use of allografts from haploidentical relatives (siblings, parents and children) in patients undergoing allogeneic blood or marrow transplant (alloBMT). More recently, second- and third-degree relatives have also been shown to be safe allograft donors. An increasing number of older patients undergoing alloBMT have been receiving allografts from haploidentical donors. However, older patients are more likely to have older siblings and children, and older donor age is associated with worse outcomes.
OBJECTIVE: In the current study, we report the safety and utility of grandchildren as haploidentical donors and compared with children as donors in patients undergoing alloBMT.
METHODS: We compared characteristics and outcomes of alloBMT patients aged 55 years and older with children older than 30 years as donors (C group; n = 276) and those with grandchildren as donors (GC group; n = 40). Because many important baseline characteristics predict outcomes after alloBMT, we performed propensity score matched analysis based on recipient age, alloBMT year, disease, graft source and haematopoietic cell transplantation comorbidity index (HCT-CI).
RESULTS: The median age of recipients was 67 years (range 55-79) in the C group and 73 years (range 57-78) in the GC group. More than 70% of recipients in the GC group were older than 70 years, compared with 27% in the C group. The median donor age was 37 years (range 31-52) in the C group and 20 years (range 14-34) in the GC group. More patients in the GC group had HCT-CI scores ≥3 than in the C group (32.5% vs. 23%, p = 0.27). Two-year overall survival did not differ between the two groups (GC 62% vs. C 60%, hazard ratio [HR] 0.96, 95% confidence interval [CI] 0.53-1.75, p = 0.90) despite recipients of allografts from grandchildren being older. The 2-year RFS was 55% in the C group compared with 50% in the GC group (HR 1.05, 95% CI 0.62-1.77, p = 0.85). Non-relapse mortality subdistribution [SD] (SDHR 1.36, 95% 0.70-2.63, p = 0.36), relapse (SDHR 0.72, 95% CI 0.33-1.58, p = 0.42) or relapse-free survival (HR 1.05, 95% CI 0.62-1.77, p = 0.85). Propensity score matching analysis showed no significant differences in 2-year overall survival (GC 64% vs. C 53%; HR 0.77, 95% CI 0.42-1.42, p = 0.40), non-relapse mortality (SDHR 1.26, 95% 0.66-2.41, p = 0.48), relapse (SDHR 0.57, 95% CI 0.21-1.52, p = 0.26) or relapse-free survival (HR 0.94, 95% CI 0.57-1.54, p = 0.81).
CONCLUSIONS: Our results indicate that outcomes of alloBMT patients with grandchild donors are similar to those with child donors, despite recipients\' older age and higher comorbidities in the GC group. Grandchildren should be considered when selecting a donor for older alloBMT recipients.

Allogeneic hematopoietic stem cell transplant (HSCT) remains the only potentially curative treatment for many hematologic malignancies (HM). We previously developed a two-step approach that separates the lymphoid and myeloid portions of the graft, allowing a consistent T cell dosing and sparing the stem cells from the effect of post-transplant cyclophosphamide (CY). The two-step approach demonstrated safety and efficacy in patients treated with myeloablative and reduced-intensity conditioning. Here, we extended our two-step platform to older and less fit patients and explored the effects of using a high dose of T cells on disease relapse and transplant outcomes. Thirty-four patients with HM were treated. Median age was 68 years old and included a minority population constituting 32%. Eighty-two percent had a hematopoietic cell transplantation comorbidity index score ≥3. Ninety-one percent were haploidentical, and the rest were matched-related donor HSCT. Following administration of fludarabine and 2 Gy total body irradiation (TBI) (13 patients) or 4 Gy TBI (21 patients) conditioning regimen, a fixed dose of 2 × 108/kg CD3+ T cells was given, followed 2 days later by CY, then infusion of CD34-selected stem cells. Overall survival (OS) was 70% at 1 year and 48% at 3 years. The cumulative incidence (CI) of non-relapse mortality (NRM) and relapse were 22% and 33% at 3 years. However, the CI of relapse was much lower for patients treated with 4 Gy TBI versus those treated with 2 Gy TBI (11% versus 54%, P = .045), while NRM was similar (23% versus 15%, P = .399). This contributed to a high OS of 64% in patients who received 4 Gy TBI-based conditioning at 3 years, with median OS not reached, although this was not statistically significant (P = .68). The median time to neutrophil and platelet recovery was 12 and 17 days, respectively. The CI of grade II acute graft-versus-host-disease (aGVHD) was 22% and 26% at 100 days and 6 months, respectively. The CI of chronic GVHD (cGVHD) was 7.5% at 3 years. There was no grade III or IV aGVHD, no severe cGVHD, and no deaths attributable to GVHD. In conclusion, the two-step approach HSCT demonstrated a low disease relapse rate and high survival in patients treated with 4 Gy TBI-based conditioning, despite a generally older and more medically compromised patient population.

BACKGROUND: The impact of social determinants of health in allogeneic transplant recipients in low- and middle-income countries is poorly described. This observational study analyzes the impact of place of residence, referring institution, and transplant cost coverage (out-of-pocket vs government-funded vs private insurance) on outcomes after allogeneic hematopoietic stem cell transplantation (alloHSCT) in two of Mexico\'s largest public and private institutions.
OBJECTIVE: To evaluate the impact of social determinants of health and their relationship with outcomes among allogeneic transplant recipients in Mexico.
METHODS: In this retrospective cohort study, we included adolescents and adults ≥ 16 years who received a matched sibling or haploidentical transplant from 2015-2022. Participants were selected without regard to their diagnosis and were sourced from both a private clinic and a public University Hospital in Mexico. Three payment groups were compared: Out-of-pocket (OOP), private insurance, and a federal Universal healthcare program \"Seguro Popular\". Outcomes were compared between referred and institution-diagnosed patients, and between residents of Nuevo Leon and out-of-state. Primary outcomes included overall survival (OS), categorized by residence, referral, and payment source. Secondary outcomes encompassed early mortality, event-free-survival, graft-versus-host-relapse-free survival, and non-relapse-mortality (NRM). Statistical analyses employed appropriate tests, Kaplan-Meier method, and Cox proportional hazard regression modeling. Statistical software included SPSS and R with tidycmprsk library.
RESULTS: Our primary outcome was overall survival. We included 287 patients, n = 164 who lived out of state (57.1%), and n = 129 referred from another institution (44.9%). The most frequent payment source was OOP (n = 139, 48.4%), followed by private insurance (n = 75, 26.1%) and universal coverage (n = 73, 25.4%). No differences in OS, event-free-survival, NRM, or graft-versus-host-relapse-free survival were observed for patients diagnosed locally vs in another institution, nor patients who lived in-state vs out-of-state. Patients who covered transplant costs through private insurance had the best outcomes with improved OS (median not reached) and 2-year cumulative incidence of NRM of 14% than patients who covered costs OOP (Median OS and 2-year NRM of 32%) or through a universal healthcare program active during the study period (OS and 2-year NRM of 19%) (P = 0.024 and P = 0.002, respectively). In a multivariate analysis, payment source and disease risk index were the only factors associated with overall survival.
CONCLUSIONS: In this Latin-American multicenter study, the site of residence or referral for alloHSCT did not impact outcomes. However, access to healthcare coverage for alloHSCT was associated with improved OS and reduced NRM.

BACKGROUND: Relapse remains a challenge after transplantation in pediatric patients with hematological malignancies. Myeloablative regimens used for disease control are associated with acute and long-term adverse effects. We used a CD45RA-depleted haploidentical graft for adoptive transfer of memory T cells combined with NK-cell addback and hypothesized that maximizing the graft-versus-leukemia (GVL) effect might allow for reduction in intensity of conditioning regimen.
METHODS: In this phase II clinical trial (NCT01807611), 72 patients with hematological malignancies (complete remission (CR)1: 25, ≥ CR2: 28, refractory disease: 19) received haploidentical CD34 + enriched and CD45RA-depleted hematopoietic progenitor cell grafts followed by NK-cell infusion. Conditioning included fludarabine, thiotepa, melphalan, cyclophosphamide, total lymphoid irradiation, and graft-versus-host disease (GVHD) prophylaxis consisted of a short-course sirolimus or mycophenolate mofetil without serotherapy.
RESULTS: The 3-year overall survival (OS) and event-free-survival (EFS) for patients in CR1 were 92% (95% CI:72-98) and 88% (95% CI: 67-96); ≥ CR2 were 81% (95% CI: 61-92) and 68% (95% CI: 47-82) and refractory disease were 32% (95% CI: 11-54) and 20% (95% CI: 6-40). The 3-year EFS for all patients in morphological CR was 77% (95% CI: 64-87) with no difference amongst recipients with or without minimal residual disease (P = 0.2992). Immune reconstitution was rapid, with mean CD3 and CD4 T-cell counts of 410/μL and 140/μL at day + 30. Cumulative incidence of acute GVHD and chronic GVHD was 36% and 26% but most patients with acute GVHD recovered rapidly with therapy. Lower rates of grade III-IV acute GVHD were observed with NK-cell alloreactive donors (P = 0.004), and higher rates of moderate/severe chronic GVHD occurred with maternal donors (P = 0.035).
CONCLUSIONS: The combination of a CD45RA-depleted graft and NK-cell addback led to robust immune reconstitution maximizing the GVL effect and allowed for use of a submyeloablative, TBI-free conditioning regimen that was associated with excellent EFS resulting in promising long-term outcomes in this high-risk population. The trial is registered at ClinicalTrials.gov (NCT01807611).

Following conventional graft-versus-host disease (GVHD) prophylaxis, the development of acute and/or chronic GVHD is associated with lower relapse rates. However, the effects of GVHD on relapse and non-relapse mortality following post-transplant cyclophosphamide (PTCy)-based GVHD prophylaxis have not been well studied. To this end, we analyzed the impact of acute and chronic GVHD following PTCy-based haploidentical donor transplantation (HIDT). The analysis included 335 consecutive HIDT recipients transplanted at a single institution between 2005 and 2021. Landmark analysis (LA) and time-dependent multivariable analysis (MVA) were utilized to study the impact of GVHD development on transplant outcome. Landmarks were defined as Day +100 for acute GVHD and one-year for chronic GVHD. Recipient characteristics included a median age of 50 (19-80) years, most commonly transplanted for acute leukemia[/MDS [242]. PBSC was the graft source in 81%, and regimen intensity was myeloablative in 49%. Median follow-up was 65 (23-207) months. In landmark analysis, development of grade 3 to 4 acute GVHD (versus 0-1) was associated with inferior 3-year overall survival (OS 47% versus 64%, P = .041), due to higher NRM (25% versus 10%, P = .013). In contrast, development of grade 2 acute GVHD had no significant effect on NRM or survival. When restricted to acute leukemia/MDS patients, development of grade II acute GVHD was associated with improved OS (79% versus 58%, P = .027) and a trend towards lower relapse (24% versus 36%, P = .08). Development of moderate-to-severe chronic GVHD resulted in significantly higher NRM (15% versus 4%, P = .010), but had no impact on relapse, DFS or OS. In Cox multivariate analysis (MVA), grade 3 to 4 acute GVHD and moderate-to-severe chronic GVHD were both associated with significantly higher NRM (HR 3.38, P < .001 and HR3.35, P < .001, respectively). In addition, grade 3 to 4 acute GVHD predicted worse OS (HR 1.80, P = .007) and DFS (HR 1.55, P = .041). In contrast, relapse was not impacted by acute or chronic GVHD in MVA. Grade 2 acute GVHD was not associated with transplant outcome in MVA. In summary, both grade 3 to 4 acute and moderate-to-severe chronic GVHD were associated with higher NRM after PTCy-based HIDT, without an effect on relapse risk. Methods of early identification of such patients in order to augment GVHD prophylaxis are clearly needed.

The landscape of HLA matching in hematopoietic cell transplantation (HCT) is continuously advancing, introducing more nuanced criteria beyond traditional 10/10 HLA-A, -B, -C, and -DRB1 allele matching. For 10/10 matched donors, prioritizing a donor with a \"core\" permissive HLA-DPB1 mismatch is recommended over \"noncore\" permissive mismatches, with nonpermissive mismatches being the least prefered. In the one-antigen mismatched setting (7/8 HLA-matched), HLA-C matching, particularly avoiding high-expression mismatches at residues 116 or 77/80, is preferred over HLA-A or HLA-B mismatches. HLA B-leader matching is beneficial in both one-antigen mismatched and haploidentical HCT. Additionally, specific HLA mismatches in haploidentical HCT, such as DRB1 mismatches with DQB1 matches and DPB1 nonpermissive mismatches are linked to better outcomes. Among non-HLA factors, evidence consistently underscores the pivotal impact of donor age on overall survival. For HLA-mismatched transplants, including haploidentical HCT, avoidance of donors against whom the recipient has preformed donor-specific antibodies is paramount. Selecting a cytomegalovirus (CMV) seronegative donor is important particularly for CMV-negative recipients; however, more research is needed in the letermovir prophylaxis era. The impact of ABO-matching on transplant outcomes is debatable. Other unanswered questions include defining \"younger\" donors and establishing hierarchy in donor selection based on factors like CMV status, ABO compatibility, or sex-mismatch, to name a few. Future research addressing these issues will refine donor selection algorithms and improve transplant success. In conclusion, selecting a donor for HCT requires multifaceted considerations, integrating evolving HLA-matching criteria and non-HLA factors, to optimize HCT outcomes in this rapidly advancing field.

BACKGROUND: The goal of this study was to assess the effect of donor type and pre-transplant immunotherapy (IST) on outcomes of hematopoietic stem cell transplantation (HSCT) for children and young adults with severe aplastic anemia (SAA).
METHODS: This retrospective, multi-center study included 52 SAA patients, treated in 5 pediatric transplant programs in Florida, who received HSCT between 2010 and 2020 as the first- or second-line treatment.
RESULTS: The median age at HSCT for all 52 patients was 15 years (range 1-25). The 3-year overall survival (OS) by donor type were as follows: 95% [95% CI 85.4-99] for matched related donors (MRD) (N = 24), 84% [95% CI 63.5-99] for haploidentical (N = 13), and 71% [95% CI 36-99] for matched unrelated donors (MUD) (N = 7). The 3-year OS was 81% [95% CI 69.7-99] for all patients, 90.5% [95% CI 79.5-99] for non-IST patients (N = 27), and 70% [95% CI 51-99] for IST patients (N = 24) (log-rank p = .04). Survival of haploidentical HSCT (haplo-HSCT) recipients with post-transplant cyclophosphamide (PTCy) (N = 13) was excellent for both groups: 100% for non-IST patients (N = 3) and 80% for IST patients (N = 10). The 3-year OS for patients with previous IST by donor type in groups where >5 patients were available was 78.8% [95% CI 52.3-99] for haplo-HSCT (N = 10) and 66.7% [95% CI 28.7-99] for MUD (N = 6). Although it appears that patients receiving HSCT ≥6 months after the start of IST had worse survival, the number of patients in each category was small and log-rank was not significant(p = .65).
CONCLUSIONS: Patients receiving MUD and haplo-HSCT with PTCy had similar outcomes, suggesting that haplo-HSCT with PTCy could be included in randomized trials of upfront IST versus alternative donor HSCT.

Allogeneic bone marrow transplantation is a curative intervention for both neoplastic and non-malignant conditions. However, not all patients have an HLA-matched donor. Therefore, the development of an approach that expand the donor pool was of paramount relevance. The development of post-transplantation cyclophosphamide as graft versus host disease prophylaxis allows the safe use of haploidentical donors, solving the donor availability problem to the vast majority of patients in need. The present paper reviews the history of the development of haploidentical transplantation at Johns Hopkins University, from the bench to the bedside.

BACKGROUND: Immune reconstitution (IR) kinetics of paediatric patients underwent haploidentical haematopoietic stem cell transplantation (HSCT) with post-transplant cyclophosphamide (PTCy) have not been extensively studied. We compared IR patterns of children receiving HSCT from haploidentical (n = 92) and HLA-matched donors (n = 36), and analysed risk factors for viral infection in these patients.
METHODS: We prospectively measured lymphocyte subset numbers before HSCT and at 1, 3, 6 and 12 months after HSCT. Blood cytomegalovirus (CMV), Epstein-Barr virus, adenovirus, BK virus (BKV) and urine adenovirus and BKV viral loads were measured at designated time points.
RESULTS: The median numbers of total T and T helper cells at 1 month were significantly lower in the haploidentical group compared with the HLA-matched group. Haploidentical HSCT recipients had significantly lower median numbers of several T cell subsets and B cells for 1 year after HSCT. The median NK cell count of the haploidentical group was lower at 1 month. BKV haemorrhagic cystitis, blood CMV and urine adenovirus reactivation were more frequently found in the haploidentical group. Post-haploidentical HSCT patients receiving anti-T lymphocyte globulin (ATG) had significantly lower median numbers of total T cells (at 1 month) and T helper cells (at 6 and 12 months) and higher rate of blood BKV reactivation compared with those without ATG.
CONCLUSIONS: Paediatric patients who undergo haploidentical HSCT with PTCy are likely to have delayed IR and an increased risk of viral reactivation/infection compared with HLA-matched HSCT. The addition of ATG to PTCy delayed T cell recovery and increased risk of BKV reactivation.