Nonmyeloablative haploidentical peripheral blood stem cell transplantation in congenital anemias

基于我们的小鼠数据，我们制定了一项1期和2期方案，采用阿仑单抗、400cGy全身照射（TBI）和移植后环磷酰胺（PT-Cy）剂量递增，队列1为0mg/kg，队列2为50mg/kg，队列3为100mg/kg。共有21例镰状细胞病患者和2例地中海贫血患者接受了移植，这些患者的基线并发症包括肝硬化、肺动脉高压、心力衰竭和终末期肾病。移植率从第一队列的1/3（33%）提高到第二队列的5/8(63%)，第三队列的10/12（83%）。在随后的队列中，供体骨髓和CD3嵌合的百分比也有所改善。中位随访超过6年，总生存率为73.9%；6例患者均在镰状细胞病复发后死亡，2例患者在重复移植后死亡。移植后100天前无死亡病例。目前，第一队列中有0%，第二队列中有12.5%，第三队列中有50%没有患病。没有2-4级急性或中重度慢性移植物抗宿主病（GVHD）。因此，我们已经证明PT-Cy可以改善早期死亡风险高的SCD患者的移植。3例患者在清除骨髓条件下与同一供者再次移植，100%供者骨髓嵌合，无镰状细胞病。当我们达到研究的停止规则时，我们开启了一个新的方案，增加了额外的免疫抑制，试图提高成功率，同时保持GVHD的低风险。自2017年6月以来，已有19例患者移植。18例患者达到了高供体嵌合水平。1例有中风史和慢性血栓栓塞性肺动脉高压的抗凝患者在第二次移植后60天死亡。12例患者中有1例发展为2级急性GVHD，对类固醇反应良好。一名患者排斥他的移植物，需要输注他的备用自体细胞。一名供体骨髓嵌合水平缓慢下降的患者在移植后2.5年镰状细胞病复发。两名患者出现难治性埃文斯综合征，随后出现意想不到的严重高炎症反应，导致两名患者多器官衰竭，其中一人死亡。目前正在对方案进行调整，试图降低毒性并改善移植物的长期功能。我们的镰状细胞病患者克隆造血方案和镰状细胞病患者主要器官的深度表型分析目前正在审查中，预计将很快开放。我们还将继续寻找与移植物排斥反应相关的早期生物标志物，试图在早期和可能更可逆的状态下识别移植物排斥反应，并探索移植物移植和耐受诱导的机制。我们还试图确定患者是否确实耐受他们的移植物，以便可以停止不必要的免疫抑制。最后，我们将在不匹配的小鼠模型和镰状细胞病小鼠模型中探索非基因毒性条件作用，试图降低长期毒性，同时保持镰状细胞病患者接受治愈性治疗的良好疗效。

Based on our murine data, we developed a phase 1 and 2 protocol employing alemtuzumab, 400cGy total body irradiation (TBI) and escalating doses of post-transplant cyclophosphamide (PT-Cy) ranging from 0mg/kg in cohort 1 and 50mg/kg in cohort 2 to 100mg/kg in cohort 3. A total of 21 patients with sickle cell disease and 2 patients with beta thalassemia were transplanted and had baseline complications including cirrhosis, pulmonary hypertension, heart failure, and end-stage renal disease. The engraftment rate improved from 1/3 (33%) in the first cohort, to 5/8 (63%) in the second cohort to 10/12 (83%) in the third cohort. Percentage of donor myeloid and CD3 chimerism also improved with subsequent cohorts. With median follow-up exceeding 6 years, overall survival is 73.9%; all 6 died after return of their sickle cell disease and 2 following repeat transplant. There was no mortality before 100 days post-transplant. At present, 0% in the first cohort, 12.5% in the second cohort, and 50% in the third cohort remain free of their disease. There was no Grade 2-4 acute or moderate to severe chronic graft-versus-host disease (GVHD). Therefore, we have shown that PT-Cy improves engraftment in patients with SCD who are at high risk for early mortality. 3 patients were re-transplanted with myeloablative conditioning and the same donor and are free of sickle cell disease with 100% donor myeloid chimerism. As we reached stopping rules for the study, we opened a new protocol which adds additional immunosuppression in an attempt to improve the success rate while maintaining a low risk of GVHD. Since June 2017, 19 patients have been transplanted. 18 patients achieved high donor chimerism levels. One patient with history of stroke and chronic thromboembolic pulmonary hypertension on anticoagulation died 60 days after her second transplant. One of the 12 developed Grade 2 acute GVHD which responded well to steroids. One patient rejected his graft and required infusion of his backup autologous cells. One patient with slowly falling donor myeloid chimerism levels experienced return of his sickle cell disease at 2.5 years post-transplant. Two patients developed refractory Evans syndrome followed by an unexpected severe hyperinflammatory reaction that led to multi-organ failure in both patients, fatal in one. The protocol is currently being adjusted in an attempt to decrease toxicity and improve long-term graft function. Our clonal hematopoiesis protocol in patients with sickle cell disease and deep phenotyping of major organs in patients with sickle cell disease are currently under review and are expected to open soon. We will also continue our search for early biomarkers associated with graft rejection in an attempt to identify graft rejection at an early and potentially more reversible state and explore mechanisms of engraftment and tolerance induction. We also seek to identify whether patients are indeed tolerant of their grafts so that unnecessary immunosuppression can be discontinued. Lastly, we will explore non-genotoxic conditioning in a mismatched murine model and the murine model of sickle cell disease in an attempt to decrease long-term toxicity while maintaining good efficacy in patients with sickle cell disease who undergo curative therapies.