1. It could potentially decrease the prevalence of SCD and significantly decrease the overall morbidity and mortality associated with SCD in children with matched sibling donors.
2. It could increase the awareness of health professionals who have a low awareness of the role of BMSCT in the treatment and cure of SCD (i.e., those in rural areas)
3. It can improve patient/family access to information and communications to facilitate informed discussion and choice for all SCD treatment options
4. It could open the gateway for more therapeutic applications for other genetic diseases

1. The science in this has evolved substantially such that BMSCT is a viable therapeutic option with reduced morbidity and mortality in the sibling matched population
2. There is an opportunity to broaden current collaborations with other agencies and the BMSCT community to expand the accessibility of their research forward.
3. Other agencies are emphasizing work in the area of BMSCT particularly for hemoglobinopathies.

The ability of allogeneic blood or marrow transplantation (BMT) to cure diverse non-malignant diseases is well-documented. However, widespread use in diseases such as sickle cell anemia that cause substantial morbidity and shorten life but are not immediately life-threatening, has been limited by transplant-related toxicity and mortality especially in the majority of these patients who lack HLA-matched donors. Several new therapeutic approaches now exist that are promising strategies, separately or in combination, for addressing issues of donor availability, graft rejection, organ toxicity and acute and chronic graft-versus-host disease more effectively. Evaluation and refinement of these therapeutic strategies in both preclinical and Phase I-III clinical trials now offers a real possibility that allogeneic BMT could be applied early in the course of these diseases, allowing normal growth, development, quality of life and lifespan. If successful, allogeneic BMT offers a major advantage over gene therapy approaches even if such approaches become possible in the future; i.e., allogeneic BMT can be done with low-dose, non-toxic conditioning while gene therapy requires high-dose myeloablative therapy which not only can be toxic/fatal to these patients who often have end-organ dysfunction but also universally induces infertility, a major concern of patient groups who usually survive beyond child-bearing years.

There are now single institution and registry (CIBMTR) data showing that related haploidentical allogeneic BMT using post-transplantation cyclophosphamide (PTCy) produces results similar to those seen with HLA-matched sibling donors. Accordingly, every patient in need of allogeneic BMT now can safely undergo the procedure, including those ethnic groups (such as African-Americans and Hispanics) who are unlikely to find a donor in unrelated registries. Combining PTCy with other approaches for preventing graft-versus-host disease (GVHD) can even eliminate GVHD and transplant-related mortality. Although recurrence of malignant diseases remains an issue, especially as GVHD is eliminated, relapse is not a concern for non-malignant diseases after successful allogeneic engraftment. Moreover, the average cost of allogeneic BMT, about $150K, is a cost-savings over the long-term management of many of these diseases. The NHLBI-funded BMT Clinical Trials Network (CTN) has developed the infrastructure to rapidly and efficiently carry out large multi-institutional BMT trials. Over the last 15 year, thousands of patients have been entered on BMT CTN trials. Of note, African-Americans and Hispanics remarkably represent 30% of the accruals on one such trial, CTN1101, studying unrelated umbilical cord and related haploidentical allogeneic BMT. However, funding for the infrastructure for continuing this work remains problematic, since BMT trials generally lack corporate funding.

To overcome this obstacle to progress in the field, we propose the creation of the funding mechanisms for a multicenter clinical trial consortium which would bring together investigators in field and facilitate study the outcomes of CT for patients with different types of donors and stem cell sources and compare them to outcomes in phenotypically matched controls receiving best available standard of care.Answering the compelling question about the role of CT in the management of SCD has the potential to have a catalytic effect in progress in this field. Patients are are then more likely to receive CT or standard of care at the appropriate time and in the manner in which they are most likely to have a positive outcome. This has the potential to reduce morbidity and premature mortality and in the long run, to decrease the burden of the disease on the healthcare system. The advent of clinical trials of gene therapies for SCD offers the prospect of even greater applicability of curative therapies. Thus, a consortium developed to answer this CQ would serve as a crucial vehicle for providing access to a greater proportion of patient to these personalized curative therapies . Such studies would also be powered to answer the question about who should receive the curative therapy, when they should receive it, and how it would impact their SCD related complications, late effects, survival and quality of life and help families make informed choice appropriate for their situation.

The increasing applicability and acceptability of HCT for SCD is evidenced by the doubling in the number of such procedures reported to CIBMTR in the decade starting 2001. Refinements in conditioning regimen and supportive care continue to improve outcomes in children and now in adults with SCD undergoing HCT from HLA matched related donors. Recently, HCT from unrelated donors and from haplo-identical donors have further increased the applicability of HCT. Opening of gene therapy trials has further raised the prospect of cure for a greater proportion of patients. These developments are evidence of the feasibility of recruitment to large multi-center comparative trials of SCD and standard of care. Recently, there has been increasing collaboration among investigators in the field with informal consortia being developed by investigators coming together to study HCT for children, adults or HCT from haplo-identical donors. These groups are also increasingly working with SCD hematologists, families and other stakeholders. There is also increasing cross-cutting collaborations with other medical specialists and behavioral and translational scientists Thus, the convergence of several factors described above suggests that the time is fortuitous for a major initiative from the NHLBI to bring investigators together and create the infrastructure that will enable these investigators to seek definitive answers to the challenging question “What is the place of curative therapy in SCD?”.

Inherited monogenic hematologic diseases such as hemophilia, beta-thalassemia and sickle cell disease are prime targets for future application of genome editing technology. However, studies are still needed to advance our understanding of the biology of genome editing as well as determine which other disorders are amenable to genome editing correction. Emphasis on preclinical research that focuses on determining the accuracy, safety and efficiency of this technology in order to help minimize off-target mutations and reduce toxicity, is essential for effective translation of this technology into the clinic. Once preclinical efficacy is established, support will be needed for clinical vector production, toxicity testing of the vectors/reagents used, and the performance of clinical trials. The gene correction strategies developed for inherited disorders will also be attractive for other hematologic diseases, and autoimmune disorders like lupus, rheumatoid arthritis, and type I diabetes). There is also a critical need for supporting preclinical validation studies, scale-up and GMP cell manufacturing, all of which could be shared infrastructures across multiple diseases in the NHLBI portfolio.

The high clinical variability in sickle cell disease (SCD) and the lack of sufficient data to help understand and or predict the course of an individual’s disease warrants the identification of better predictors of disease severity. The identification of predictors of disease severity, such as biomarkers, will be vital in the management and treatment of SCD, especially since more recently several plasma biomarkers and certain genetic polymorphisms have been proposed to influence specific clinical outcomes, including stroke, sickle cell nephropathy, and survival. Furthermore, studies of biomarkers or genetic markers in the context of clinical drug trials may be helpful in predicting response rates, thus allowing for more personalized therapeutic decisions.

Hydroxyurea is a widely available disease-modifying therapy for sickle cell disease (SCD), but its effectiveness is currently limited by inadequate utilization, and less than optimal response. Research is needed to improve adherence to this evidence-based therapy and emphasis needs to be placed on determining whether therapy with hydroxyurea can prevent or even reverse organ dysfunction. In addition, research identifying new adjunct therapies to blood transfusion and hydroxyurea, as well as disease-specific therapies for co-morbidities such as kidney disease, hypertension, obstructive lung disease, and pulmonary hypertension will be valuable in the management and treatment of SCD.

One million HSCT mile stone was recently reached and the utilization of HSCTs continues to increase. For many non-malignant hematologic conditions particularly sickle cell anemia and bone marrow failure syndromes, HSCT is the only potentially curative option. Most HSCT survivors are living beyond a year, but can suffer from devastating complications of HSCT which include graft-versus-host-disease, second cancers, diabetes, infertility, congestive heart failure, blindness, and bronchiolitis obliterans, besides many others which lead to increased overall HSCT related disease burden. A lot of efforts are currently being put in cancer survivorship by the ACS, NCI, ASCO and other societies, but very little emphasis is being laid on sickle cell or aplastic anemia survivors. This area of HSCT survivorship becomes more important from health disparities perspective too, since majority of the hemoglobinopathy HSCTs performed in the US are in racial minorities. Comparative effectiveness research (CER) in HSCT survivorship is essential to delineate the overall disease burden this population and understand the risks and outcomes of HSCT late effects. To compare the effectiveness of survivorship programs and research, especially for those survivors who are at risk of health disparities is a top priority of the Institute of Medicine CER 2009 initiative.

Majority of the HSCT survivors of benign hematologic conditions are now living beyond 2 years post-HSCT. Blood and Marrow Transplant (BMT) Clinical Trials Network (CTN) was established in 2001 to conduct large Multi-Institutional clinical trials and is funded by the NHLBI. Since the infrastructure is in place to conduct studies related to all aspects of HSCT, this would be an area to explore first from feasibility perspective since thousands of patients have already been successfully enrolled through the BMT-CTN studies. From NHLBI strategic perspective, this would place CTN (and Emmes Corporation) in an excellent unique position of addressing CER for survivorship issues and health disparities within one study, since the population understudy would mainly be consistent of racial minorities – with the overall goal of improving the long term health, preventing late effects, improving quality of life, and reduce the overall health burden (DALYs and societal costs) of thousands of HSCT survivors in the US and globally.

SCD is the most common genetic disease in the United States affecting 100,000 individuals or 1 in 400 African American births. Pain, stroke, acute chest syndrome and priapism are common morbidities affecting patients with sickle cell disease, which often result in emergency room visits and/or hospitalizations. Despite advances in treatment, sickle cell disease is associated with significant mortality and shortened life expectancy. Defining the optimal role of red blood cell exchange and plasma exchange (which may be used to remove plasma molecules such as inflammatory factors and free hemoglobin) in the management and prevention of the complications of sickle cell disease and may not only prolong the life of these patients but is expected to improve the quality of their lives. In addition, clearly defining the indications for simple verses exchange transfusion therapy has the potential to minimize both alloimmunization to red blood cells (reported to occur in up to 75% of patients with sickle cell disease) and iron overload associated with transfusion.

Transfusion therapy may be efficacious to sickle cell patients by providing increased oxygen delivery to tissues and/or decreasing the amount of sickle hemoglobin present by suppression of erythropoiesis. Understanding the relative contributions of these mechanisms will assist with optimal use of transfusion therapy as well as inform the development of novel alternative therapies

Multi-center trials should be feasible, given the number of patients with sickle cell disease in the US. Participation by larger academic centers which care for sickle cell patients should facilitate trials. Methods for automated red cell exchange and plasma exchange are available and in common use at many centers. Great interest exists among physicians caring for sickle cell patients (as exemplified by the recent NIH consensus document and ASFA sickle cell consensus conference) which is a strength of this proposal. Challenges include agreement on standard treatment protocols across centers and long term follow up of patients. Maintaining vascular access in sickle cell patients is another challenge when performing apheresis procedures on sickle cell patients

Studies on epigenetic mechanisms have extraordinary promise for the development of transformative therapeutic approaches for non-malignant hematologic disorders, however, limited progress has been made in advancing therapies to counteract the often crippling complications of these conditions. In the case of sickle cell disease, an ensemble of proteins has been implicated in mediating the epigenetic repression of gamma-globin expression, raising the possibility that antagonizing the actions of these proteins to increase gamma-globin expression may be a useful treatment strategy. However, in certain cases, some of these proteins are deemed “undruggable,” based on their structural attributes. There is a critical need to identify druggable components of the multi-step epigenetic mechanisms as well as develop better models and assays that will more effectively identify modulators of “undruggable” proteins. Given the rich proteome and improved technologies available today, studies of proteomics, metabolomics, and regulatory RNAs are likely to reveal promising translational avenues. In addition, approaches to modifying the expression of the components of this pathway are underway using developing gene therapy strategies, such as viral vectors and/or gene editing can quickly advance therapy in sickle cell disease and β-thalassmia.

Pain is the most common clinical manifestation of sickle cell disease (SCD) and accounts for a large proportion of emergency department visits and hospitalizations. Due to its impact on the patients’ quality of life, there is a need for more basic and clinical research studies focused on understanding the mechanisms of different pain syndromes as well as the role of neurotransmitters and inflammation in acute and chronic SCD pain. Also, comparative effectiveness studies in the management of chronic pain will be crucial in helping to improve the patients’ overall quality of life.

Transfusion of RBC is major adjunct in the management of trauma, acute and chronic illness. Issues in blood transfusion include availability of donors, RBC typing and crossmatching, cold storage of donor cells, and limited viability of stored RBC. Globally, in many situations where blood is critically needed, these systems are not available.
An increasing percentage of people with SCD require regular RBC transfusion to prevent stroke and other major complications. In addition, RBC transfusion is employed repeatedly in the management of serious acute complications of SCD. Transfusion of normal RBC to replace or supplement the patient’s defective RBC is the most effective intervention in the management of SCD.

Impacts:
• Molecular genotyping of RBC will reduce alloimmunization.
• Use of new generation HBOCs that do not require blood typing, crossmatching, refrigeration, and that do not transmit infection, would save lives in conditions of severe hemorrhage, stroke, possibly heart attack, especially where there is no immediate access to adequate medical facilities.
• In SCD, HBOCs could prevent pain or reduce its severity and duration, prevent stroke, reduce severity of acute chest syndrome, and other vasoocclusive complications. Finally, HBOCs have the potential to alter the pathogenesis of SCD.

The problems in managing chronic RBC transfusion in SCD remain the same as they have been for decades: all immunization, iron overload, and infection transmission. It is clear that traditional serological RBC phenotyping is unable to detect several variants of RBC antigens, especially those in the Rh system, in populations of African descent. This leads to erroneous phenotyping and the appearance of “auto antibodies” that are truly alloantibodies resulting from transfusion of mismatched blood. As a result, people with SCD are the most frequent users of the American Rare Donor Program.

would open up opportunities for more patients to get cured of their sickle cell disease without co morbidity of the BMT process

Need to develop animal models and also newer marrow niche clearing agents.

Bone marrow transplant criteria has become less restrictive yet there has not been a steep increase in procedures. My understanding is that a sibling or child with the trait can be a donor. At some point this treatment needs to become more widely accessible and discussed with all patients by their doctors.

It has been reported for many decades that the sickle cell trait population are an asymptomatic group; however, there have been an increasing number of reports in the media and the medical literature suggesting the opposite.

It is very difficult for many living with SCD to maintain employment (many people have to rely on disability benefits to survive) finish school, even maintain relationships. Greater understanding of the financial and social impact would enable advocacy and direct patient service organizations to better prepare the transitioning population, reducing the financial strain on the individual and the growing medical debt incurred by hospitals and government social service programs.