A Standard Nonmyeloablative Transplantation Regimen for Adults with Sickle Cell Disease: Are We There Yet?

Incidence and risk factors of pain crisis after hematopoietic cell transplantation for sickle cell disease

ABSTRACT

Vaso-occlusive episodes (VOC) or pain crises are the most common indications for hematopoietic cell transplantation (HCT) for sickle cell disease (SCD). Elimination of pain crisis after HCT is an important patient-centered outcome and may improve understanding of the natural history of pain syndromes in SCD. We examined deidentified records of 763 patients followed-up for a median of 36.7 months (range, 0.3-168.6 months), with 69.6% patient's age <18 years at HCT, 83.3% patient's Karnofsky-Lansky performance score (KPS) ≥90, overall survival 92.9%, event-free survival 72.4%, graft failure (GF) 22.4%, AGVHD 21.4%, CGVHD 27%, and pain crisis 8.65%. On unadjusted logistic regression, increased risk of pain crisis after HCT was observed in patient's aged >10 years at HCT (range, 11-17 years; OR, 9.43; 95% CI, 3.20-27.79; P < .0001), in age ≥18 years (OR, 16.62; 95% CI, 5.85-47.16; P < .0001), in those with history of pain crisis 2 years before HCT (OR, 13.16; 95% CI, 4.08-42.42; P < .0001), alternate donors (haploidentical [OR, 4.80; 95% CI, 2.48-9.31; P < .0001], unrelated matched [OR, 2.71; 95% CI, 1.23-5.97; P = .0132], and mismatched unrelated [OR, 3.19; 95% CI, 1.44-7.05; P = .0041], and those with GF (n = 41 [5.37%]; OR, 7.15; 95% CI, 4.20-12.18; P < .0001). Pain crisis was less frequent with KPS of ≥90 (OR, 0.31; 95% CI, 0.18-0.55; P < .0001). Multivariable logistic regression models confirmed age at HCT, KPS, graft type, donor type, history of VOC 2 years before HCT, and GF as independent predictors of pain crisis after HCT and generated predictive models and nomograms for pain crisis after HCT for SCD, which can support shared decision making.

Health-Related Quality of Life and Personal Life Goals of Adults With Sickle Cell Disease After Hematopoietic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (HSCT) from a human leukocyte antigen (HLA)-matched sibling donor offers a unique therapy to reverse SCD. This mixed-methods study explores recipients' perception of HSCT success, personal life goals, and associated health-related quality of life (HRQOL) more than 1 year after HSCT. Recipients completed the Short Form-36, version 1 (SF-36v1) HRQOL survey followed by a 60- to 90-min face-to-face or telephone audio-recorded interview. Eleven of 15 eligible recipients participated in the study. Although the eight HRQOL subscale scores varied, the three recipients with a successful HSCT and the highest scores were pursuing their personal life goals. The four with avascular necrosis (AVN) had lower scores related to AVN limitations, yet they were pursuing their personal goals. The two reporting a failed HSCT had reverted back to having SCD, and their subscale scores were among the lowest. Our results show that HSCT success, ability to pursue goals, and HRQOL align in predictable ways.

Bone marrow transplantation for adolescents and young adults with sickle cell disease: Results of a prospective multicenter pilot study

We conducted a multicenter pilot investigation of the safety and feasibility of bone marrow transplantation (BMT) in adults with severe sickle cell disease (SCD) (NCT 01565616) using a reduced toxicity preparative regimen of busulfan (13.2 mg/kg), fludarabine (175 mg/m2 ) and thymoglobulin (6 mg/kg) and cyclosporine or tacrolimus and methotrexate for graft-vs-host disease (GVHD) prophylaxis. Twenty-two patients (median age 22 years; range 17-36) were enrolled at eight centers. Seventeen patients received marrow from an HLA-identical sibling donor and five patients received marrow from an 8/8 HLA-allele matched unrelated donor. Before BMT, patients had stroke, acute chest syndrome, recurrent pain events, were receiving regular red blood cell transfusions, or had an elevated tricuspid regurgitant jet (TRJ) velocity, which fulfilled eligibility criteria. Four patients developed grades II-III acute GVHD (18%) and six developed chronic GVHD (27%) that was moderate in two and severe in one patient. One patient died of intracranial hemorrhage and one of GVHD. Nineteen patients had stable donor chimerism, 1-year post-transplant. One patient who developed secondary graft failure survives disease-free after a second BMT. The one-year overall survival and event-free survival (EFS) are 91% (95% CI 68%-98%) and 86% (95% CI, 63%-95%), respectively, and 3-year EFS is 82%. Statistically significant improvements in the pain interference and physical function domains of health-related quality of life were observed. The study satisfied the primary endpoint of 1-year EFS ≥70%. This regimen is being studied in a prospective clinical trial comparing HLA-matched donor BMT with standard of care in adults with severe SCD (NCT02766465).

Curative therapies: Allogeneic hematopoietic cell transplantation from matched related donors using myeloablative, reduced intensity, and nonmyeloablative conditioning in sickle cell disease

Sickle cell disease (SCD) chronically damages multiple organs over the lifetime of affected individuals. Allogeneic hematopoietic cell transplantation (allo-HCT) is the most studied curative intervention. Fully matched related marrow, peripheral blood derived, or cord blood HCT have the best transplant outcome for symptomatic patients with SCD. For patients with asymptomatic or milder disease who have this donor option available, risks and benefits of HCT should be discussed among the patient, family, treating hematologist, and transplant physician, and decision to proceed to HCT should be individualized. Myeloablative conditioning with busulfan, cyclophosphamide, and ATG has been a commonly employed regimen for children and young adults. Recently, low intensity conditioning with low dose total body irradiation and alemtuzumab is emerging as an efficacious and safe regimen for adults, young adults, and possibly children. Mixed donor chimerism (minimum ≥20% myeloid cells), from myeloablative or nonmyeloablative conditioning regimen, produces robust normal donor erythropoiesis and is sufficient to provide a clinical cure. The proportion of patients remaining on immunosuppression beyond 2 years post-HCT is likely <10% with either myeloablative or low intensity regimens. Late effects from myeloablative or reduced intensity conditioning, or from several more months of immunosuppression in low intensity conditioning may be less common than those observed in HCT for malignant indications. Nonmyeloablative approaches with low toxicities should be the focus of future research efforts. Prevention of GVHD is a shared goal in all approaches of allo-HCT in SCD.

Allogenic peripheral stem cell transplantation from HLA-matched related donors for adult sickle cell disease: remarkable outcomes from a single-center trial

Adult patients with sickle cell disease (SCD) are highly susceptible to stem cell transplant complications, including drug toxicity, graft versus host disease (GVHD), and graft rejection due to SCD-related tissue damage, endothelial activation, and inflammation. The scarcity of compatible stem cells for transplantation further limits treatment options, with only 43 cases of adult allogeneic peripheral blood stem cell transplantation (allo-PSCT) from human leukocyte antigen (HLA)-identical sibling donors reported in the international registry for the period 1986-2013. Herein we report remarkable outcomes in a cohort of adult SCD patients who underwent allo-PSCT using a fludarabine (Flu), busulfan (Bu), and anti-T-cell lymphocyte globulin (ATG)-based conditioning regimen in combination with very low dose total body irradiation (TBI), followed by post-transplant cyclophosphamide (Cy) and sirolimus as GVHD prophylaxis. We performed a single-center, retrospective study consisting of 20 consecutive patients (mean age 33.4 years) who underwent allo-PSCT from HLA-matched related donors with a conditioning regimen of Flu 150/Bu 3.2/Cy 29/ATG 30 (Fresenius)/TBI 200 between September 2013 and September 2017. Data were validated by an independent data audit group of the affiliated JACIE-accredited transplantation center. All patients experienced a sustained donor cell engraftment. Full donor chimerism (total cell) occurred within 180 days in all patients. Mean duration of follow-up was 13.8 months (range: 0.3-50 months), with 12 (60%) patients completing 12 months. No non-relapse mortality or graft rejection occurred. Successful treatment was achieved without the presence of graft loss, grade III-IV acute GVHD, extensive chronic GVHD, or other major complications. Allo-PSCT in combination with Flu 150/Bu 3.2/Cy 29/ATG 30(Fresenius)/TBI 200- Cy/Sirolimus therapy yielded encouraging outcomes with no mortality and low incidence of GVHD. Further controlled studies will be necessary to compare transplant protocols and long-term outcomes.