Phenotypic screening of the ReFRAME drug repurposing library to discover new drugs for treating sickle cell disease.

Stem cell transplantation and genetic therapies offer potential cures for patients with sickle cell disease (SCD), but these options require advanced medical facilities and are expensive. Consequently, these treatments will not be available for many years to the majority of patients suffering from this disease. What is urgently needed now is an inexpensive oral drug in addition to hydroxyurea, the only drug approved by the FDA that inhibits sickle-hemoglobin polymerization. Here, we report the results of the first phase of our phenotypic screen of the 12,657 compounds of the Scripps ReFRAME drug repurposing library using a recently developed high-throughput assay to measure sickling times following deoxygenation to 0% oxygen of red cells from sickle trait individuals. The ReFRAME library is a very important collection because the compounds are either FDA-approved drugs or have been tested in clinical trials. From dose-response measurements, 106 of the 12,657 compounds exhibit statistically significant antisickling at concentrations ranging from 31 nM to 10 µM. Compounds that inhibit sickling of trait cells are also effective with SCD cells. As many as 21 of the 106 antisickling compounds emerge as potential drugs. This estimate is based on a comparison of inhibitory concentrations with free concentrations of oral drugs in human serum. Moreover, the expected therapeutic potential for each level of inhibition can be predicted from measurements of sickling times for cells from individuals with sickle syndromes of varying severity. Our results should motivate others to develop one or more of these 106 compounds into drugs for treating SCD.

Optimizing haematopoietic stem and progenitor cell apheresis collection from plerixafor-mobilized patients with sickle cell disease.

We adjusted haematopoietic stem and progenitor cell (HSPC) apheresis collection from patients with sickle cell disease (SCD) by targeting deep buffy coat collection using medium or low collection preference (CP), and by increasing anticoagulant-citrate-dextrose-solution A dosage. In 43 HSPC collections from plerixafor-mobilized adult patients with SCD, we increased the collection efficiency to 35.79% using medium CP and 82.23% using low CP. Deep buffy coat collection increased red blood cell contamination of the HSPC product, the product haematocrit was 4.7% with medium CP and 6.4% with low CP. These adjustments were well-tolerated and allowed efficient HSPC collection from SCD patients.

Non-myeloablative human leukocyte antigen-matched related donor transplantation in sickle cell disease: outcomes from three independent centres.

Non-myeloablative haematopoietic progenitor cell transplantation (HPCT) from matched related donors (MRD) has been increasingly utilized in sickle cell disease (SCD). A total of 122 patients received 300 cGy of total body irradiation (TBI), alemtuzumab, unmanipulated filgrastim-mobilized peripheral blood HPC and sirolimus. The median follow-up was four years; median age at HPCT was 29 years. Median neutrophil and platelet engraftment occurred on day 22 and 19 respectively; 41 patients required no platelet transfusions. Overall and sickle-free survival at one and five years were 93% and 85% respectively. Age, sex, pre-HPCT sickle complications, ferritin and infused HPC numbers were similar between graft failure and engrafted patients. Mean donor myeloid chimaerism at one and five years post HPCT were 84% and 88%, and CD3 was 48% and 53% respectively. Two patients developed grade 1 and 2 skin graft-versus-host disease (GVHD) with no chronic GVHD. Median days of recipients taking immunosuppression were 489; 83% of engrafted patients have discontinued immunosuppression. Haemoglobin, haemolytic parameters and hepatic iron levels improved post HPCT. Pulmonary function testing, hepatic histology and neurovascular imaging remained stable, suggesting cessation of further sickle-related injury. Fourteen patients had children. In this largest group of adult SCD patients, this regimen was highly efficacious, well-tolerated despite compromised organ functions pre HPCT, and without clinically significant GVHD.

Busulfan Combined with Immunosuppression Allows Efficient Engraftment of Gene-Modified Cells in a Rhesus Macaque Model.

Busulfan conditioning is utilized for hematopoietic stem cell (HSC) depletion in the context of HSC gene-therapy conditioning but may result in insufficient immunosuppression. In this study, we evaluated whether additional immunosuppression is required for efficient engraftment of gene-modified cells using a rhesus HSC lentiviral gene-therapy model. We transduced half of rhesus CD34+ cells with an enhanced green fluorescent protein (GFP)-encoding vector (immunogenic) and the other half with a γ-globin-encoding vector (no predicted immunogenicity). After autologous transplantation of both transduced cell populations following myeloablative busulfan conditioning (5.5 mg/kg/day for 4 days), we observed immunological rejection of GFP-transduced cells up to 3 months post-transplant and stable engraftment of γ-globin-transduced cells in two animals, demonstrating that ablative busulfan conditioning is sufficient for engraftment of gene-modified cells producing non-immunogenic proteins but insufficient to permit engraftment of immunogenic proteins. We then added immunosuppression with abatacept and sirolimus to busulfan conditioning and observed engraftment of both GFP- and γ-globin-transduced cells in two animals, demonstrating that additional immunosuppression allows for engraftment of gene-modified cells expressing immunogenic proteins. In conclusion, myeloablative busulfan conditioning should permit engraftment of gene-modified cells producing non-immunogenic proteins, while additional immunosuppression is required to prevent immunological rejection of a neoantigen.

Kinetic assay shows that increasing red cell volume could be a treatment for sickle cell disease.

Although it has been known for more than 60 years that the cause of sickle cell disease is polymerization of a hemoglobin mutant, hydroxyurea is the only drug approved for treatment by the US Food and Drug Administration. This drug, however, is only partially successful, and the discovery of additional drugs that inhibit fiber formation has been hampered by the lack of a sensitive and quantitative cellular assay. Here, we describe such a method in a 96-well plate format that is based on laser-induced polymerization in sickle trait cells and robust, automated image analysis to detect the precise time at which fibers distort ("sickle") the cells. With this kinetic method, we show that small increases in cell volume to reduce the hemoglobin concentration can result in therapeutic increases in the delay time prior to fiber formation. We also show that, of the two drugs (AES103 and GBT440) in clinical trials that inhibit polymerization by increasing oxygen affinity, one of them (GBT440) also inhibits sickling in the absence of oxygen by two additional mechanisms.

Cytomegalovirus Infection Incidence and Risk Factors Across Diverse Hematopoietic Cell Transplantation Platforms Using a Standardized Monitoring and Treatment Approach: A Comprehensive Evaluation from a Single Institution.

Human cytomegalovirus (CMV) infection and disease remains a significant cause of morbidity and mortality for hematopoietic cell transplantation (HCT) recipients. Disruption of or weak reconstitution of virus-specific cellular immune function, such as with certain HCT approaches, poses significant risk for CMV-related complications. The incidence of and risk factors for CMV infection and the nature of CMV disease were evaluated retrospectively among 356 consecutive HCT recipients transplanted at the National Institutes of Health using all graft sources, including bone marrow, peripheral blood stem cell (PBSC), and umbilical cord blood (UCB), and a range of in vivo and ex vivo approaches for graft-versus-host disease (GVHD) prophylaxis. The cumulative incidence of CMV infection was higher for CMV-seropositive recipients at 33%, regardless of donor CMV serostatus. Patients transplanted with CMV-seropositive donors had a significantly shorter duration of antiviral therapy. Among graft sources UCB was associated with the highest cumulative incidence of CMV infection at 65% and significantly longer treatment duration at a median of 36days, whereas PBSC HCT was associated with the lowest incidence at 26% and the shortest CMV treatment duration at a median of 21days. There were significant differences in the cumulative incidence of CMV infection by T cell manipulation strategy when systemic steroids were included as a risk-modifying event. Over one-third of CMV infections occurred in the setting of systemic steroid administration. CMV disease occurred in 5% of HCT recipients, with 70% of cases in the setting of treatment for GVHD. Although factors related to serostatus, graft source, and GVHD prophylaxis were associated with varied CMV infection incidence, unplanned post-HCT corticosteroid therapy contributed greatly to the incidence of both CMV infection and disease across HCT approaches, highlighting this post-HCT intervention as a key time to potentially tailor the approach to monitoring, preemptive therapy, and even prophylaxis.

Vibration Controlled Transient Elastography (Fibroscan®) in sickle cell liver disease - could we strike while the liver is hard?

Vibration controlled transient elastography (VCTE) is validated for the evaluation of hepatic fibrosis in different liver diseases. Sickle cell liver disease (SCLD) results from a cumulative hepatic injury and its lifelong and progressive nature raises the need for a non-invasive tool for fibrosis evaluation. Fifty patients, aged between 23 and 59 years with sickle cell disease and suspected SCLD underwent a VCTE followed by a liver biopsy. Biopsies were evaluated for various scores of liver disease that were then correlated to VCTE score. 90% of our patients had an Ishak Fibrosis (IF) score between 0-2 (Group A-minimal to no fibrosis) and 10% of the patients had IF score between 3-6 (Group B-advanced fibrosis). The median Transient Elastography (TE) for patients in Groups A and B was 4·8 kilopascals (kPa) and 17·6 kPa, respectively. A positive correlation was shown between TE and IF score, R = 0·0·68 (P = <0·0001); a positive correlation was also shown with Histology Activity Index fibrosis score, R = 0·64 (P = <0·0001). This study emphasises the need for further studies of non-invasive tools and their utility in liver fibrosis evaluation of patients with SCLD.

Natural history of benign ethnic neutropenia in individuals of African ancestry.

BACKGROUND: Benign ethnic neutropenia (BEN), defined by neutrophil count <1.5 k/µL in the absence of other causes, is an asymptomatic condition more commonly observed in individuals of African ancestry. However, the natural history of this condition has been less well described. METHODS: Individuals with BEN were retrospectively identified by chart review or referral to hematology clinics. They were then invited to enroll in a prospective natural history study. Retrospective and prospective clinical and laboratory data were combined for descriptive analyses. FINDINGS: 46 participants, younger and older adults from 2 institutions, had BEN. Hypertension was reported in 30%, musculoskeletal disorders in 15%, and upper respiratory infection in 33% of these adults. Their leukopenia resulted from isolated neutropenia, ranging from 1000 and 1500 cells/µL. The severity of infections was mild and the frequency was similar to other healthy individuals in the ambulatory clinic. INTERPRETATION: In this group of BEN participants, their leukopenia was stable over time, and they had low rates of infections or common medical disorders, confirming the benign nature of this condition. The presence of BEN in children, younger adults, and older adults suggest a hereditary pattern for BEN.

At least 20% donor myeloid chimerism is necessary to reverse the sickle phenotype after allogeneic HSCT.

Novel curative therapies using genetic transfer of normal globin-producing genes into autologous hematopoietic stem cells (HSCs) are in clinical trials for patients with sickle cell disease (SCD). The percentage of transferred globin necessary to cure SCD is currently not known. In the setting of allogeneic nonmyeloablative HSC transplants (HSCTs), stable mixed chimerism is sufficient to reverse the disease. We regularly monitored 67 patients after HSCT. After initially robust engraftment, 3 of these patients experienced declining donor myeloid chimerism (DMC) levels with eventual return of disease. From this we discovered that 20% DMC is necessary to reverse the sickle phenotype. We subsequently developed a mathematical model to test the hypothesis that the percentage of DMC necessary is determined solely by differences between donor and recipient red blood cell (RBC) survival times. In our model, the required 20% DMC can be entirely explained by the large differences between donor and recipient RBC survival times. Our model predicts that the requisite DMC and therefore necessary level of transferred globin is lowest in patients with the highest reticulocyte counts and concomitantly shortened RBC lifespans.

Ex vivo immunological evaluation of stable mixed chimeric patients after matched related donor allogeneic transplantation in sickle cell disease.

BACKGROUND AIMS: Allogeneic hematopoietic stem cell transplantation is curative for sickle cell disease, and the use of matched related donors, non-myeloablative conditioning and sirolimus immunosuppression results in stable mixed chimerism without graft-versus-host disease (GVHD). However, the time to terminate sirolimus while maintaining mixed chimerism is unclear. METHODS: In this study, we developed a two-way mixed lymphocyte reaction (MLR) to evaluate ex vivo immunoreaction in mixed chimeric patients. RESULTS: In co-culture of peripheral blood mononuclear cells (PBMCs) from two healthy controls (without irradiation), we detected proliferation at various ratios of PBMC mixtures (1:9 to 9:1) as well as various concentrations of sirolimus, suggesting that two-way MLR is applicable to patients (having >10% chimerism) undergoing sirolimus treatment. In two-way MLR using PBMCs (including donor and recipient cells) from mixed chimeric patients (n = 28), greater ex vivo proliferation was observed <6 months compared with >6 months post-transplant and healthy control PBMC monoculture. Robust ex vivo proliferation was observed in a patient with acute GVHD, and persistent ex vivo proliferation (until 2 years) was observed in a patient with decreasing donor chimerism. CONCLUSIONS: In summary, we demonstrated that in two-way MLR, ex vivo immunoreaction decreases to low levels ~6 months post-transplant. These findings suggest a rationale to continue immunosuppression for 6 months.

Efficient Generation of ß-Globin-Expressing Erythroid Cells Using Stromal Cell-Derived Induced Pluripotent Stem Cells from Patients with Sickle Cell Disease.

Human embryonic stem (ES) cells and induced pluripotent stem (iPS) cells represent an ideal source for in vitro modeling of erythropoiesis and a potential alternative source for red blood cell transfusions. However, iPS cell-derived erythroid cells predominantly produce ε- and γ-globin without ß-globin production. We recently demonstrated that ES cell-derived sacs (ES sacs), known to express hemangioblast markers, allow for efficient erythroid cell generation with ß-globin production. In this study, we generated several iPS cell lines derived from bone marrow stromal cells (MSCs) and peripheral blood erythroid progenitors (EPs) from sickle cell disease patients, and evaluated hematopoietic stem/progenitor cell (HSPC) generation after iPS sac induction as well as subsequent erythroid differentiation. MSC-derived iPS sacs yielded greater amounts of immature hematopoietic progenitors (VEGFR2 + GPA-), definitive HSPCs (CD34 + CD45+), and megakaryoerythroid progenitors (GPA + CD41a+), as compared to EP-derived iPS sacs. Erythroid differentiation from MSC-derived iPS sacs resulted in greater amounts of erythroid cells (GPA+) and higher ß-globin (and ßS-globin) expression, comparable to ES sac-derived cells. These data demonstrate that human MSC-derived iPS sacs allow for more efficient erythroid cell generation with higher ß-globin production, likely due to heightened emergence of immature progenitors. Our findings should be important for iPS cell-derived erythroid cell generation. Stem Cells 2017;35:586-596.

Diagnostic challenges of prolonged post-treatment clearance of Plasmodium nucleic acids in a pre-transplant autosplenectomized patient with sickle cell disease.

BACKGROUND: Autosplenectomy, as a result of sickle cell disease, is an important risk factor for severe malaria. While molecular methods are helpful in providing rapid and accurate infection detection and species identification, the effect of hyposplenism on result interpretation during the course of infection should be carefully considered. CASE PRESENTATION: A 32-year old autosplenectomized Nigerian male with severe sickle cell disease was referred to the National Institutes of Health for allogenic hematopoietic stem cell transplant. Despite testing negative for malaria by both smear and PCR 2 weeks after arrival in the USA, the patient developed fever and diffuse bilateral lower rib cage and upper abdominal pain 2 weeks later and subsequently tested positive for Plasmodium falciparum. Parasitaemia was tracked over time by microscopy and nucleic acid tests to evaluate the therapeutic response in the setting of hyposplenism. The patient showed prompt resolution of patent infection by microscopy but remained positive by molecular methods for > 30 days after treatment initiation. CONCLUSION: While molecular testing can provide sensitive Plasmodium nucleic acid detection, the persistence of Plasmodium nucleic acids following adequate treatment in functionally asplenic patients can lead to a diagnostic dilemma. In such patients, clinical response and peripheral blood smears should guide patient management following treatment. Nonetheless, in pre-transplant patients at high-risk for pre-existing Plasmodium infections, highly sensitive molecular assays can be useful to rule out infection prior to transplantation.

Chronic Administration of Hydroxyurea (HU) Benefits Caucasian Patients with Sickle-Beta Thalassemia.

In sickle cell disease (SCD), hydroxyurea (HU) treatment decreases the number of vaso-occlusive crisis (VOC) and acute chest syndrome (ACS) by increasing fetal hemoglobin (HbF). Data are lacking regarding the frequency of HU dose modification or whether sub-therapeutic doses (<15 mg/kg/day) are beneficial. We reviewed the medical records of 140 patients from 2010 to 2014. The laboratory parameters and SCD complications were compared between the first and last visits based on HU use. Fifty patients (36%) never took HU or suspended HU ("no HU" group). Among patients taking <15 mg/kg/day HU on their first visit, half remained at the same dose, and the other half increased to ≥15 mg/kg/day. Among patients taking ≥15 mg/kg/day, 17% decreased to <15 mg/kg/day, and 83% stayed at ≥15 mg/kg/day. The "no HU" group had fewer episodes of VOC and ACS. Both HU treatment groups had a reduction in both complications (p < 0.0001). This improvement was observed in all SCD phenotypes. The white blood cell (WBC) counts were found to be lower, and HbF increased in both HU groups (p = 0.004, 0.001). The maximal HbF response to HU in HbS/ß⁺-thalassemia was 20%, similar to those observed for HbSS (19%) and HbS/ß°-thalassemia (22%). HbS/ß⁺-thalassemia could have a similar disease severity as HbSS or HbS/ß°-thalassemia. Patients with HbS/ß°-thalassemia or HbS/ß⁺-thalassemia phenotypes responded to HU.

National Institutes of Health Hematopoietic Cell Transplantation Late Effects Initiative: The Patient-Centered Outcomes Working Group Report.

In 2015, the National Institutes of Health convened six working groups to address the research needs and best practices for late effects of hematopoietic stem cell transplantation survivors. The Patient-Centered Outcomes Working Group, charged with summarizing the HRQOL evidence base, used a scoping review approach to efficiently survey the large body of literature in adult and pediatric HCT survivors over 1 year after transplantation. The goals of this paper are to (1) summarize the current literature describing patient-centered outcomes in survivors, including the various dimensions of health-related quality of life affected by HCT, and describe interventions tested to improve these outcomes; (2) highlight areas with sufficient evidence allowing for integration into standard practice; (3) address methodological issues that restrict progress in this field; (4) identify major gaps to guide future research; and (5) specify priority research recommendations. Patient-centered outcomes were summarized within physical, psychological, social, and environmental domains, as well as for adherence to treatment, and health behaviors. Interventions to improve outcomes were evaluated for evidence of efficacy, although few interventions have been tested in long-term HCT survivors. Methodologic issues defined included lack of consistency in the selection of patient-centered outcome measures, along with the absence of a standard for timing, frequency, and mode of administration. Recommendations for HCT survivorship care included integration of annual screening of patient-centered outcomes, use of evidence-based practice guidelines, and provision of treatment summaries and survivorship care plans after HCT. Three priority research recommendations included the following: (1) design and test risk-targeted interventions with dose-intensity modulation matching the needs of HCT survivors with priority domains, including sexual dysfunction, fatigue, sleep disruption, nonadherence to medications and recommended health care, health behaviors including physical inactivity and healthy eating, and psychological dysfunction, with particular consideration of novel technologies to reach HCT survivors distant from their transplantation centers; (2) design a consensus-based methodologic framework for outcomes evaluation; and (3) evaluate and compare existing practices for integrating patient-centered outcome screening and interventions across HCT survivorship programs.

Severe cardiac iron toxicity in two adults with sickle cell disease.

BACKGROUND: Use of chronic blood transfusions as a treatment modality in patients with blood disorders places them at risk for iron overload. Since patients with ß-thalassemia major (TM) are transfusion-dependent, most studies on iron overload and chelation have been conducted in this population. While available data suggest that compared to TM, patients with sickle cell disease (SCD) have a lower risk of extrahepatic iron overload, significant iron overload can develop. Further, previous studies have demonstrated a direct relationship between iron overload and morbidity and mortality rates in SCD. However, reports describing the outcome for patients with SCD and cardiac iron overload are rare. STUDY DESIGN AND METHODS: We performed a retrospective analysis and identified two SCD patients with cardiac iron overload. We provide detailed descriptions of both cases and their outcomes. RESULTS: Serum ferritin levels ranged between 17,000 and 19,000 µg/L. Both had liver iron concentrations in excess of 35 mg of iron per gram of dried tissue as well as evidence of cardiac iron deposition on magnetic resonance imaging. One patient died of an arrhythmia and had evidence of severe multiorgan iron overload via autopsy. On the other hand, after appropriate therapy, a second patient had improvement in cardiac function. CONCLUSION: Improper treatment of iron overload in SCD can lead to a fatal outcome. Alternatively, iron overload may potentially be prevented or reversed with judicious use of blood transfusions and early use of chelation therapy, respectively.

Alternative Donor/Unrelated Donor Transplants for the ß-Thalassemia and Sickle Cell Disease.

Considerable progress with respect to donor source has been achieved in allogeneic stem cell transplant for patients with hemoglobin disorders, with matched sibling donors in the 1980s, matched unrelated donors and cord blood sources in the 1990s, and haploidentical donors in the 2000s. Many studies have solidified hematopoietic progenitors from matched sibling marrow, cord blood, or mobilized peripheral blood as the best source-with the lowest graft rejection and graft versus host disease (GvHD), and highest disease-free survival rates. For patients without HLA-matched sibling donors, but who are otherwise eligible for transplant, fully allelic matched unrelated donor (8/8 HLA-A, B, C, DRB1) appears to be the next best option, though an ongoing study in patients with sickle cell disease will provide data that are currently lacking. There are high GvHD rates and low engraftment rates in some of the unrelated cord transplant studies. Haploidentical donors have emerged in the last decade to have less GvHD; however, improvements are needed to increase the engraftment rate. Thus the decision to use unrelated cord blood units or haploidentical donors may depend on the institutional expertise; there is no clear preferred choice over the other. Active research is ongoing in expanding cord blood progenitor cells to overcome the limitation of cell dose, including the options of small molecule inhibitor compounds added to ex vivo culture or co-culture with supportive cell lines. There are inconsistent data from using 7/8 or lower matched unrelated donors. Before routine use of these less matched donor sources, work is needed to improve patient selection, conditioning regimen, GvHD prophylaxis, and/or other strategies.

Early Diagnosis of Labial Fusion in Women After Allogeneic Hematopoietic Cell Transplant Enables Outpatient Treatment.

OBJECTIVE: The aim of the study was to describe the presentation and successful treatment of labial fusion in women after allogeneic hematopoietic cell transplantation (HCT). MATERIALS AND METHODS: During routine posttransplant gynecologic evaluation, labial fusion was identified in 5 female patients. Clinical data were collected regarding underlying disease, transplant regimen, genital symptoms, systemic sites of chronic graft-versus-host disease (cGvHD) and treatment, and follow-up. RESULTS: At presentation, women had a median age of 40 years (range = 35-50) and were 23-month to 8-year post-HCT. Four of the 5 patients with labial fusion had evidence of active cGvHD; 3 patients had severe sclerotic cGvHD, and 1 patient had bronchiolitis obliterans. One had rheumatoid arthritis and had recently stopped taking etanercept, but had no sites of cGvHD. One patient presented with only a pinpoint opening for passage of urine. Her complete labial fusion was lysed under general anesthesia. Three of the 4 others presented with dyspareunia. Their labia were fused between the clitoris and urethra narrowing the vaginal opening without obstructing the urethra. These labial adhesions were successfully lysed during an office procedure. Once the labial mucosa healed, the patients applied topical clobetasol and estrogen to prevent reagglutination. On follow-up, 1 month to 1 year later, all women were significantly improved. CONCLUSIONS: These patients highlight the importance of asking women who have undergone allogeneic HCT, especially those with severe cGvHD, about dyspareunia and dysuria. Those with genital symptoms warrant referral to a gynecologist. These cases illustrate that labial fusion, if diagnosed early enough, may be treated successfully with an office procedure and medical therapy.