Nonmyeloablative haploidentical peripheral blood stem cell transplantation in congenital anemias

基于我们的小鼠数据，我们制定了一期和二期方案，采用阿伦图珠单抗，400cGy全身照射(TBI)，并将移植后环磷酰胺(PT-Cy)的剂量从0 mg/kg(队列1)和50 mg/kg(队列2)递增到100 mg/kg(队列3)。共有21名镰状细胞疾病患者和2名β地中海贫血患者接受了移植，其基本并发症包括肝硬变、肺动脉高压、心力衰竭和终末期肾脏疾病。植入率从第一组的1/3(33%)提高到第二组的5/8(63%)到第三组的10/12(83%)。随着后续队列的进行，供者髓系和CD3嵌合体的百分比也有所改善。中位随访期超过6年，总存活率为73.9%；所有6例患者在镰状细胞病复发后死亡，2例再次移植后死亡。移植后100天前无死亡病例。目前，第一队列中的0%、第二队列中的12.5%和第三队列中的50%保持无病状态。无2-4级急性或中至重度慢性移植物抗宿主病(GVHD)。因此，我们发现PT-Cy可改善早期死亡风险较高的SCD患者的植入率。3例患者接受清髓预适应和同一供者的再次移植，无镰状细胞病，供者骨髓嵌合率为100%。当我们达成这项研究的终止规则时，我们打开了一个新的方案，增加了额外的免疫抑制，试图在保持低GVHD风险的同时提高成功率。自2017年6月以来，已有19名患者进行了移植。18例患者的供者嵌合水平较高。1例患者有中风和慢性血栓栓塞性肺动脉高压的抗凝治疗史，在第二次移植后60天死亡。12例中有1例发生了对激素反应良好的2级急性移植物抗宿主病。一名患者排斥了他的移植物，需要输注他的备用自体细胞。一名供者骨髓嵌合体水平缓慢下降的患者在移植后2.5年经历了镰状细胞疾病的复发。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炎症反应，导致两名患者发生多器官衰竭，其中一名患者死亡。目前正在调整该方案，试图降低毒性并改善长期移植物功能。我们的镰状细胞病患者的克隆造血方案和镰状细胞病患者主要器官的深度表型目前正在审查中，预计很快就会开放。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，试图识别移植物排斥反应的早期和更可逆的状态，并探索移植和耐受诱导的机制。我们还试图确定患者是否真的对移植物有耐受性，以便可以停止不必要的免疫抑制。最后，我们将探索在不匹配的小鼠模型和镰状细胞病的小鼠模型中进行非遗传毒性调节，试图在接受根治治疗的镰状细胞病患者保持良好疗效的同时减少长期毒性。

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.