Curative Therapies for Sickle Cell Disease

Lipid Levels Increase to the Normal Range After Nonmyeloablative Hematopoietic Cell Transplantation for Sickle Cell Disease

Individuals with sickle cell disease (SCD) have a unique type of dyslipidemia characterized by low total cholesterol (TC), low low-density lipoprotein cholesterol (LDL-c), low high-density lipoprotein cholesterol (HDL-c), and normal triglycerides (TG). This lipid state is theorized to be cardioprotective against atherosclerosis. In SCD, hematopoietic cell transplant (HCT) offers a potentially curative therapy. Long-term survivors of HCT for hematologic malignancies are at increased risk for dyslipidemia and atherosclerosis long-term. The effects of HCT on SCD dyslipidemia are unknown. This retrospective cohort study characterizes lipid profiles at baseline and after nonmyeloablative allogeneic HCT for SCD. We analyzed data from 116 patients after nonmyeloablative HLA-matched sibling or haploidentical HCT for SCD at the NIH from 2009 to 2021. TC, HDL-c, LDL-c, and TG were collected pre-HCT, 1-year post-HCT, and annually thereafter. Data were analyzed using linear generalized estimating equation regression modeling. Successful HCT was associated with a rise in TC, LDL-c, and HDL-c and a decline in TG post-HCT. After HCT, previously low lipid levels increased to the normal range. These changes occurred within the first year of HCT and were maintained thereafter. In patients with graft failure, TC and LDL-c levels remain unchanged from their pre-HCT baseline. Sirolimus use for graft versus host disease prophylaxis was associated with higher TG levels. These findings suggest that SCD dyslipidemia resolves with reversal of the SCD phenotype. The normalization of lipid parameters suggests SCD patients are not at increased risk for atherosclerosis after successful HCT compared to their peers; further studies with longer follow-up are required.

Cerebral Hemodynamic Responses to Disease-Modifying and Curative Sickle Cell Disease Therapies

BACKGROUND AND OBJECTIVES

Sickle cell disease (SCD) is a hemoglobinopathy resulting in hemoglobin-S production, hemolytic anemia, and elevated stroke risk. Treatments include oral hydroxyurea, blood transfusions, and hematopoietic stem cell transplantation (HSCT). Our objective was to evaluate the neurologic relevance of these therapies by characterizing how treatment-induced changes in hemoglobin (Hb) affect brain health biomarkers.

METHODS

In this interventional study, adults with and without SCD underwent a 3T-MRI at Vanderbilt University Medical Center at 2 time points before and after clinically indicated transfusion or HSCT or at 2 time points without the introduction of a new Hb-altering therapy (adult controls and patients with SCD on hydroxyurea). Cerebral blood flow (CBF; mL/100 g/min) and cerebral venous blood relaxation rate (s-1; a marker of Hb and blood oxygen content) responses were assessed to understand how these markers of brain health vary with Hb modulation. CBF was assessed with arterial spin labeling MRI, and blood relaxation rate was assessed using T2 relaxation under spin tagging MRI. Measures were pairwise compared within each cohort using a 2-tailed Wilcoxon signed-rank test, and regression was applied to evaluate the parameter and Hb change relationships. The significance criterion was 2-sided p < 0.05.

RESULTS

Adults with (n = 43; age 28.7 ± 7.7 years; 42% male) and without (n = 13; age 33.5 ± 12.2 years; 46% male) SCD were evaluated. In adults receiving hydroxyurea (n = 10), neither Hb, CBF, nor venous relaxation rate changed between time 1 (Hb = 8.6 ± 1.2 g/dL) and time 2 (Hb = 9.0 ± 1.8 g/dL) (all p > 0.05). In transfusion patients (n = 19), Hb increased from 8.2 ± 1.4 g/dL to 9.3 ± 1.3 g/dL before vs after transfusion (p < 0.001), paralleling a CBF decrease of 14.2 mL/100 g/min (p < 0.001) toward control levels. The venous relaxation rate did not change after transfusion (p = 0.71). In HSCT patients (n = 14), Hb increased from 8.9 ± 1.9 g/dL to 12.9 ± 2.7 g/dL (p < 0.001) before vs after transplant, paralleling CBF decreases from 68.16 ± 20.24 to 47.43 ± 12.59 mL/100 g/min (p < 0.001) and increase in venous relaxation rate (p = 0.004). Across the Hb spectrum, a CBF decrease of 5.02 mL/100 g/min per g/dL increase in Hb was observed.

DISCUSSION

Findings demonstrate improvement in cerebral hemodynamics after transfusion and transplant therapies compared with hydroxyurea therapy; quantitative relationships should provide a framework for using these measures as trial end points to assess how new SCD therapies affect brain health.

Development of a quantitative prediction algorithm for human cord blood-derived CD34+ hematopoietic stem-progenitor cells using parametric and non-parametric machine learning models

The transplantation of CD34+ hematopoietic stem-progenitor cells (HSPCs) derived from cord blood serves as the standard treatment for selected hematological, oncological, metabolic, and immunodeficiency disorders, of which the dose is pivotal to the clinical outcome. Based on numerous maternal and neonatal parameters, we evaluated the predictive power of mathematical pipelines to the proportion of CD34+ cells in the final cryopreserved cord blood product adopting both parametric and non-parametric algorithms. Twenty-four predictor variables associated with the cord blood processing of 802 processed cord blood units randomly sampled in 2020-2022 were retrieved and analyzed. Prediction models were developed by adopting the parametric (multivariate linear regression) and non-parametric (random forest and back propagation neural network) statistical models to investigate the data patterns for determining the single outcome (i.e., the proportion of CD34+ cells). The multivariate linear regression model produced the lowest root-mean-square deviation (0.0982). However, the model created by the back propagation neural network produced the highest median absolute deviation (0.0689) and predictive power (56.99%) in comparison to the random forest and multivariate linear regression. The predictive model depending on a combination of continuous and discrete maternal with neonatal parameters associated with cord blood processing can predict the CD34+ dose in the final product for clinical utilization. The back propagation neural network algorithm produces a model with the highest predictive power which can be widely applied to assisting cell banks for optimal cord blood unit selection to ensure the highest chance of transplantation success.

Zinc finger nuclease-mediated gene editing in hematopoietic stem cells results in reactivation of fetal hemoglobin in sickle cell disease

BIVV003 is a gene-edited autologous cell therapy in clinical development for the potential treatment of sickle cell disease (SCD). Hematopoietic stem cells (HSC) are genetically modified with mRNA encoding zinc finger nucleases (ZFN) that target and disrupt a specific regulatory GATAA motif in the BCL11A erythroid enhancer to reactivate fetal hemoglobin (HbF). We characterized ZFN-edited HSC from healthy donors and donors with SCD. Results of preclinical studies show that ZFN-mediated editing is highly efficient, with enriched biallelic editing and high frequency of on-target indels, producing HSC capable of long-term multilineage engraftment in vivo, and express HbF in erythroid progeny. Interim results from the Phase 1/2 PRECIZN-1 study demonstrated that BIVV003 was well-tolerated in seven participants with SCD, of whom five of the six with more than 3 months of follow-up displayed increased total hemoglobin and HbF, and no severe vaso-occlusive crises. Our data suggest BIVV003 represents a compelling and novel cell therapy for the potential treatment of SCD.

Advancing life: innovative approaches to enhance survival in sickle cell anemia patients

Sickle cell anemia (SCA) is a severe genetic disorder characterized by the production of abnormal hemoglobin S, leading to the formation of sickle-shaped red blood cells that cause chronic anemia, pain, and organ damage. This review explores recent innovative strategies aimed at improving survival rates and quality of life for SCA patients. Genetic therapies, particularly gene editing with CRISPR-Cas9 and gene therapy using lentiviral vectors, have shown significant potential in correcting the genetic defects responsible for SCA. Clinical trials demonstrate that these approaches can reduce sickle cell crises and minimize the need for blood transfusions by enabling the production of healthy red blood cells. Novel pharmacological treatments such as voxelotor, crizanlizumab, and L-glutamine provide additional mechanisms to prevent hemoglobin polymerization, reduce vaso-occlusive episodes, and decrease oxidative stress, respectively. These therapies offer new hope for patients, particularly those who do not respond adequately to existing treatments. Improved blood transfusion protocols, including automated red cell exchange and advanced donor-matching techniques, have enhanced the safety and efficacy of transfusions, reducing complications like alloimmunization. Comprehensive care models, integrating multidisciplinary care teams, patient education, and telemedicine, have further contributed to better disease management. By providing holistic care that addresses both medical and psychosocial needs, these models improve patient adherence to treatment and overall health outcomes. This review highlights the importance of these innovative strategies and calls for continued research and development to sustain and expand these advancements in SCA care.

Reproductive Health Assessment and Reports of Fertility Counseling in Pediatric and Adolescent Patients with Sickle Cell Disease After Hematopoietic Cell Transplantation

Conditioning regimens for hematopoietic cell transplant (HCT) in patients with sickle cell disease (SCD) place patients at risk for reproductive health issues. The purpose of this study was to assess reproductive health and reports of fertility counseling in patients with SCD who received a transplant. This was a secondary analysis of gonadal hormone production, future infertility risk assessment, and parent-proxy/patient reports of fertility counseling in SCD transplant recipients who are currently pubertal and were enrolled in the Atlanta sites of the Sickle Cell Transplant Evaluation of Long-term and Late Effects Registry (STELLAR) between May 2017 and October 2023. Clinical information was abstracted from medical records and reproductive health survey data from the STELLAR database. Descriptive statistics were reported as median (interquartile range [IQR]) or percentages. There were 20 females and 12 males in the study population. Females were median (IQR) 19.6 (9.4) years old and males 20.8 (11.4) years old at the time of the study. Transplants most commonly occurred in the decade 2010 to 2019 at 10.7 (4.8) years old for females and 11.1 (4.1) years old for males. Most participants received bone marrow stem cells (95.0% females, 100.0% males) from matched sibling donors (90.0% females, 100.0% males). Participants received one of seven HCT conditioning regimens with cyclophosphamide equivalent doses ranging from 3388 to 9706 mg/m2. The majority of females (90.0%) had diminished ovarian reserve with low anti-Mullerian hormone levels, and 61.1% had premature ovarian insufficiency with two follicle-stimulating hormone levels (FSH) ≥40 mIU/mL post-HCT. All males had normal testosterone levels, but 63.6% had elevated FSH levels suggestive of impaired spermatogenesis post-HCT. Parent proxies (for patients <18 years old) and patients ≥18 years old completed surveys 9.0 years (5.2) and 7.9 years (9.3) since HCT in females and males respectively. Twenty-five percent of parent proxies and 45% of patients reported that they had not been informed by a healthcare provider of the risk of infertility post-transplant. There are high rates of gonadal dysfunction post-HCT, but many parent proxies and patients do not recall being told of the risk for future infertility. More effective methods of education are warranted to ensure SCD patients and their families clearly understand the risk for reproductive health issues post-HCT.

Advances in pharmacotherapy for sickle cell disease: what is the current state of play?

INTRODUCTION

Despite over 100 years of neglect and insufficient funding, sickle cell disease has risen to the top of the discussions due to the recent approval of two new genetic therapies. Prior to these approvals, there were only four prior approved medications for sickle cell disease in spite of being the most common inherited blood disorder. The advent and expense of these new genetic therapies have finally brought the trials and tribulations associated with SCD including the suffering and early mortality of affected individuals to the much-needed limelight. Presently, questions about how these therapies will be used and what that means for ongoing pharmaceutical development remain.

AREAS COVERED

Here, we wish to highlight the current medications and treatments for SCD using already published literature as well as scrutinize the tedious process of implementation for these newly approved commercial genetic therapies.

EXPERT OPINION

In our expert opinion, despite the progress we have made, significant challenges remain and the most important requirement for any of these treatments is ensuring all affected individuals have access to a sickle cell specialist who can provide comprehensive care.

Ex vivo prime editing of patient haematopoietic stem cells rescues sickle-cell disease phenotypes after engraftment in mice

Sickle-cell disease (SCD) is caused by an A·T-to-T·A transversion mutation in the β-globin gene (HBB). Here we show that prime editing can correct the SCD allele (HBBS) to wild type (HBBA) at frequencies of 15%-41% in haematopoietic stem and progenitor cells (HSPCs) from patients with SCD. Seventeen weeks after transplantation into immunodeficient mice, prime-edited SCD HSPCs maintained HBBA levels and displayed engraftment frequencies, haematopoietic differentiation and lineage maturation similar to those of unedited HSPCs from healthy donors. An average of 42% of human erythroblasts and reticulocytes isolated 17 weeks after transplantation of prime-edited HSPCs from four SCD patient donors expressed HBBA, exceeding the levels predicted for therapeutic benefit. HSPC-derived erythrocytes carried less sickle haemoglobin, contained HBBA-derived adult haemoglobin at 28%-43% of normal levels and resisted hypoxia-induced sickling. Minimal off-target editing was detected at over 100 sites nominated experimentally via unbiased genome-wide analysis. Our findings support the feasibility of a one-time prime editing SCD treatment that corrects HBBS to HBBA, does not require any viral or non-viral DNA template and minimizes undesired consequences of DNA double-strand breaks.

Managing the Cerebrovascular Complications of Sickle Cell Disease: Current Perspectives

The importance of protecting brain function for people with sickle cell disease (SCD) cannot be overstated. SCD is associated with multiple cerebrovascular complications that threaten neurocognitive function and life. Without screening and preventive management, 11% of children at 24% of adults with SCD have ischemic or hemorrhagic strokes. Stroke screening in children with SCD is well-established using transcranial Doppler ultrasound (TCD). TCD velocities above 200 cm/s significantly increase the risk of stroke, which can be prevented using chronic red blood cell (RBC) transfusion. RBC transfusion is also the cornerstone of acute stroke management and secondary stroke prevention. Chronic transfusion requires long-term management of complications like iron overload. Hydroxyurea can replace chronic transfusions for primary stroke prevention in a select group of patients or in populations where chronic transfusions are not feasible. Silent cerebral infarction (SCI) is even more common than stroke, affecting 39% of children and more than 50% of adults with SCD; management of SCI is individualized and includes careful neurocognitive evaluation. Hematopoietic stem cell transplant prevents cerebrovascular complications, despite the short- and long-term risks. Newer disease-modifying agents like voxelotor and crizanlizumab, as well as gene therapy, may treat cerebrovascular complications, but these approaches are investigational.

An Integrative Review: The Evolution of Provider Knowledge, Attitudes, Perceptions and Perceived Barriers to Caring for Patients with Sickle Cell Disease 1970-Now

Approximately 100,000 Americans have sickle cell disease (SCD). In the USA, the majority of patients with SCD are of African descent. Due to persistent racial and ethnic disparities in healthcare in the USA, patients with SCD experience disproportionately more health inequities because of providers' implicit biases regarding patient race. Lack of access to health insurance, lack of transportation to healthcare providers, and inadequate provider knowledge contribute to the morbidity and mortality of patients with SCD. The purpose of this integrative review was to analyze and synthesize the literature on providers' knowledge, perceptions, beliefs, and attitudes toward patients with SCD. A modified (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) method was used to conduct a comprehensive review of the literature yielding 31 publications included in this review. Three connected, yet distinct areas of focus were identified: (1) providers' knowledge, attitudes, and perceptions of patients with SCD; (2) providers' perceived or true barriers to caring for patients with SCD; and (3) interventions to improve providers' attitudes, perceptions, and care of patients with SCD. In each area of focus, research has evolved over time. Also included in this integrative review is a synthesis of measurement instruments used to assess provider knowledge, attitudes, perceptions, and perceived and true barriers to caring for patients with SCD. Adolescents with SCD who are transitioning from pediatric to adult care are at a particularly high risk for morbidity and mortality, so this review focused on the many opportunities that exist to advance the healthcare for young adults with SCD to improve patient outcomes later in life. This includes improving providers' knowledge, perceptions, beliefs, and attitudes, and lessening the real or perceived barriers to care for patients with SCD.

An overview of cord blood stem cell transplantation in Hong Kong

Haematopoietic stem cell graft derived from cord blood is standard therapy for several haematological malignancies and other diseases. The study reports cases of public and private (family) cord blood biobanking services and the related hematopoietic stem cell transplantation ever performed in Hong Kong. The published original research papers and review articles from inception to Nov 2022 have been searched for on Pubmed, Microsoft Academic Search, and Google Scholar to identify reports on existing or terminated cord blood biobanking and transplantation service in Hong Kong. Moreover, all data publicly available on the official websites of the local cord blood banks and local mainstream media has been analysed. The public Hong Kong Red Cross Blood Transfusion Service delivers the highest quantity of haematopoietic stem cell transplants. Among the private sector, HealthBaby releases the most cord blood units for clinical use in diseases in both autologous and allogeneic administration, followed by Cordlife HK.  Both public and private (family) cord blood biobanks have been and continue to contribute to the Hong Kong cord blood donor registry. However, the growth of the cord blood inventory is detrimental to donor-recipient matching for lifesaving therapy.

Kruppel-like factor 1-GATA1 fusion protein improves the sickle cell disease phenotype in mice both in vitro and in vivo

Sickle cell disease (SCD) and β-thalassemia are among the most common genetic disorders worldwide, affecting global health and mortality. Hemoglobin A2 (HbA2, α2δ2) is expressed at a low level in adult blood due to the lack of the Kruppel-like factor 1 (KLF1) binding motif in the δ-globin promoter region. However, HbA2 is fully functional as an oxygen transporter, and could be a valid antisickling agent in SCD, as well as a substitute for hemoglobin A in β-thalassemia. We have previously demonstrated that KLF1-GATA1 fusion protein could interact with the δ-globin promoter and increase δ-globin expression in human primary CD34+ cells. We report the effects of 2 KLF1-GATA1 fusion proteins on hemoglobin expression, as well as SCD phenotypic correction in vitro and in vivo. Forced expression of KLF1-GATA1 fusion protein enhanced δ-globin gene and HbA2 expression, as well as reduced hypoxia-related sickling, in erythroid cells cultured from both human sickle CD34+ cells and SCD mouse hematopoietic stem cells (HSCs). The fusion proteins had no impact on erythroid cell differentiation, proliferation, and enucleation. Transplantation of highly purified SCD mouse HSCs expressing KLF1-GATA1 fusion protein into SCD mice lessened the severity of the anemia, reduced the sickling of red blood cells, improved SCD-related pathological alterations in spleen, kidney, and liver, and restored urine-concentrating ability in recipient mice. Taken together, these results indicate that the use of KLF1-GATA1 fusion constructs may represent a new gene therapy approach for hemoglobinopathies.

Clinical outcome of pre-operative blood transfusion for sickle cell disease patients in post-operative complications

BACKGROUND

Preoperative blood transfusion for patients with sickle cell disease is a debatable topic and it can be lifesaving. Sickle cell disease patients are at high risk for vaso-occlusive crisis due to the large concentration of sickle hemoglobin (HgbS) in their blood. Despite the current extensive research into this disease, there is still no consensus over whether blood transfusion is a preferable preoperative modality among patients undergoing elective surgical procedures.

METHOD

A retrospective observational study, which enrolled 204 patients with Sickle cell disease who underwent surgery at King Fahad Hospital of the University (KFHU) over the last five years. The primary objective was to determine whether there is evidence that preoperative blood transfusion for SCD patients undergoing surgical procedures will reduce postoperative complications related to SCD.

RESULTS

A total of 204 patients were included, of which 30% had preoperative blood transfusion. Majority of patient 44% had undergone cholecystectomy. On multivariate logistic regression analysis, patients who did not undergo blood transfusion had significantly higher risk to develop post-operative SCD complications (OR=3.07, P value= 0.002). In addition, they had significantly prolonged hospitalization (OR= 2.22, P value= 0.08). In contrast, patients who received blood transfusion had lower risk for developing post-operative SCD related complications (OR=1.87, P value= 0.29), and decrease in the duration of hospitalization by (OR=0.49, P value= 0.045).

CONCLUSION

Our study showed that patients who had not undergo preoperative blood transfusion had higher risk to develop postoperative complications and prolonged hospital stay compared to those who underwent blood transfusion.

Decision making for hematopoietic stem cell transplantation in pediatric, adolescent, and young adult patients with a hemoglobinopathy-Shared or not?

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) offers an established curative option for sickle cell disease (SCD) and thalassemia patients but is associated with significant risks. Decision making is a complex process and shared decision making (SDM) could be a fitting approach in case of such preference-sensitive decisions. This study investigated what level of SDM is used in conversations with hemoglobinopathy patients and/or their caregivers considering HSCT as a curative treatment option.

METHODS

Longitudinal, descriptive study using the Observing-Patient-Involvement-in-Decision-Making scale (OPTION⁵ ) scale to determine the level of SDM in conversations with 26 hemoglobinopathy patients and/or their caregivers.

RESULTS

The total mean OPTION⁵ score was 43%, which is a moderate SDM approach. There was no difference between conversations with thalassemia patients and SCD patients. Conversations needing an interpreter scored worse than nontranslated conversations. The best scoring OPTION⁵ item was item 3: "informing about the various treatment options" (mean score 2.3 on scale 0-4). For OPTION⁵ item 4: "eliciting patients' preferences" a more skilled effort was measured for SCD patients compared to thalassemia patients.

CONCLUSIONS

The mean OPTION⁵ score of "moderate" was achieved mainly by giving information on available options, which is primarily a one-way communication. The SDM process can be improved by actively inviting patients to deliberate about options and including their elicited preferences in decision making.

Cell and Gene Therapy for Anemia: Hematopoietic Stem Cells and Gene Editing

Hereditary anemia has various manifestations, such as sickle cell disease (SCD), Fanconi anemia, glucose-6-phosphate dehydrogenase deficiency (G6PDD), and thalassemia. The available management strategies for these disorders are still unsatisfactory and do not eliminate the main causes. As genetic aberrations are the main causes of all forms of hereditary anemia, the optimal approach involves repairing the defective gene, possibly through the transplantation of normal hematopoietic stem cells (HSCs) from a normal matching donor or through gene therapy approaches (either in vivo or ex vivo) to correct the patient’s HSCs. To clearly illustrate the importance of cell and gene therapy in hereditary anemia, this paper provides a review of the genetic aberration, epidemiology, clinical features, current management, and cell and gene therapy endeavors related to SCD, thalassemia, Fanconi anemia, and G6PDD. Moreover, we expound the future research direction of HSC derivation from induced pluripotent stem cells (iPSCs), strategies to edit HSCs, gene therapy risk mitigation, and their clinical perspectives. In conclusion, gene-corrected hematopoietic stem cell transplantation has promising outcomes for SCD, Fanconi anemia, and thalassemia, and it may overcome the limitation of the source of allogenic bone marrow transplantation.

Advances in Sickle Cell Disease Treatments

Sickle Cell Disease (SCD) is an inherited disorder of red blood cells that is caused by a single mutation in the β -globin gene. The disease, which afflicts millions of patients worldwide mainly in low income countries, is characterized by high morbidity, mortality and low life expectancy. The new pharmacological and non-pharmacological strategies for SCD is urgent in order to promote treatments able to reduce patient's suffering and improve their quality of life. Since the FDA approval of HU in 1998, there have been few advances in discovering new drugs; however, in the last three years voxelotor, crizanlizumab, and glutamine have been approved as new therapeutic alternatives. In addition, new promising compounds have been described to treat the main SCD symptoms. Herein, focusing on drug discovery, we discuss new strategies to treat SCD that have been carried out in the last ten years to discover new, safe, and effective treatments. Moreover, non-pharmacological approaches, including red blood cell exchange, gene therapy and hematopoietic stem cell transplantation will be presented.

Bone fragility in patients affected by congenital diseases non skeletal in origin

BACKGROUND

Bone tissue represents a large systemic compartment of the human body, with an active metabolism, that controls mineral deposition and removal, and where several factors may play a role. For these reasons, several non-skeletal diseases may influence bone metabolism. It is of a crucial importance to classify these disorders in order to facilitate diagnosis and clinical management. This article reports a taxonomic classification of non-skeletal rare congenital disorders, which have an impact on bone metabolism METHODS: The International Osteoporosis Foundation (IOF) Skeletal Rare Diseases Working Group (SRD-WG), comprised of basic and clinical scientists, has decided to review the taxonomy of non-skeletal rare disorders that may alter bone physiology.

RESULTS

The taxonomy of non-skeletal rare congenital disorders which impact bone comprises a total of 6 groups of disorders that may influence the activity of bone cells or the characteristics of bone matrix.

CONCLUSIONS

This paper provides the first comprehensive taxonomy of non-skeletal rare congenital disorders with impact on bone physiology.

Getting blood out of a stone: Identification and management of patients with poor hematopoietic cell mobilization

Hematopoietic cell transplantation (HCT) has become a primary treatment for many cancers. Nowadays, the primary source of hematopoietic cells is by leukapheresis collection of these cells from peripheral blood, after a forced egress of hematopoietic cells from marrow into blood circulation, a process known as "mobilization". In this process, mobilizing agents disrupt binding interactions between hematopoietic cells and marrow microenvironment to facilitate collection. As the first essential step of HCT, poor mobilization, i.e. failure to obtain a desired or required number of hematopoietic cell, is one of the major factors affecting engraftment or even precluding transplantation. This review summarizes the available mobilization regimens using granulocyte-colony stimulating factor (G-CSF) and plerixafor, as well as the current understanding of the factors that are associated with poor mobilization. Strategies to mobilize patients or healthy donors who failed previous mobilization are discussed. Multiple novel agents are under investigation and some of them have shown the potential to enhance the mobilization response to G-CSF and/or plerixafor. Further investigation of the risk factors including genetic factors will offer an opportunity to better understand the molecular mechanism of mobilization and help develop new therapeutic strategies for successful mobilizations.

Fertility Preservation for Adolescents Receiving Cancer Therapies

According to the National Cancer Institute, ∼300,000 children globally are diagnosed with cancer each year. Advancements in chemotherapy and radiotherapy have revolutionized cancer treatment and improved long-term survival. Although many survivors will remain in good health with disease-free prognoses, three fourths will experience short-term and long-term effects from treatment. The cancer care paradigm has now appropriately shifted to include quality of life in survivorship with fertility cited as one of the most important quality of life indicators by survivors. A comprehensive approach to fertility preservation in adolescents receiving cancer therapies is described in this chapter.