Chronic ulcer in a patient with essential thrombocythemia taking hydroxyurea.

Chronic skin ulcers in patients with suspected pyoderma gangrenosum can, on closer inspection and further workup, have a different cause. Recognition of key features on clinical examination such as the presence of atrophie blanche is key to avoid misdiagnosis of pyoderma gangrenosum and its subsequent treatment with high-dose corticosteroids and other immunosuppressive medications.

Towards genomic medicine: a tailored next-generation sequencing panel for hydroxyurea pharmacogenomics in Tanzania.

BACKGROUND: Pharmacogenomics of hydroxyurea is an important aspect in the management of sickle cell disease (SCD), especially in the era of genomic medicine. Genetic variations in loci associated with HbF induction and drug metabolism are prime targets for hydroxyurea (HU) pharmacogenomics, as these can significantly impact the therapeutic efficacy and safety of HU in SCD patients. METHODS: This study involved designing of a custom panel targeting BCL11A, ARG2, HBB, HBG1, WAC, HBG2, HAO2, MYB, SAR1A, KLF10, CYP2C9, CYP2E1 and NOS1 as potential HU pharmacogenomics targets. These genes were selected based on their known roles in HbF induction and HU metabolism. The panel was designed using the Illumina Design Studio (Illumina, San Diego, CA, USA) and achieved a total coverage of 96% of all genomic targets over a span of 51.6 kilobases (kb). This custom panel was then sequenced using the Illumina MiSeq platform to ensure high coverage and accuracy. RESULTS: We are reporting a successfully designed Illumina (MiSeq) HU pharmacogenomics custom panel encompassing 51.6 kilobases. The designed panel achieved greater than 1000x amplicon coverage which is sufficient for genomic analysis. CONCLUSIONS: This study provides a valuable tool for research in HU pharmacogenomics, especially in Africa where SCD is highly prevalent, and personalized medicine approaches are crucial for improving patient outcomes. The custom-designed Illumina (MiSeq) panel, with its extensive coverage and high sequencing depth, provides a robust platform for studying genetic variations associated with HU response. This panel can contribute to the development of tailored therapeutic strategies, ultimately enhancing the management of SCD through more effective and safer use of hydroxyurea.

Potential of Anti-Leukotriene Drugs as New Therapeutic Agents for Inhibiting Cholangiocarcinoma Progression.

Cholangiocarcinoma (CCA) is a cancer with a poor prognosis due to difficulties in diagnosis and limited treatment options, highlighting the urgent need for new targeted therapies. In a clinical setting, we found that leukotriene levels in bile were higher than in serum. Immunohistochemical analysis of surgically resected samples also revealed that CysLT receptor 1 (CysLTR1) was more highly expressed in CCA than in normal bile duct tissue, prompting us to investigate leukotriene as a potential therapeutic target in CCA. In vitro studies using CCA cell lines expressing CysLTR1 showed that leukotriene D4, a major ligand of CysLTR1, promoted cell proliferation, with increased phosphorylation of AKT and extracellular signal-regulated kinase 1/2 (ERK1/2). Additionally, treatment with two clinically available anti-allergic drugs-zileuton, an inhibitor of CysLT formation, and montelukast, a CysLTR1 inhibitor-had inhibitory effects on cell proliferation and migratory capacity, accompanied by the reduced phosphorylation of AKT and ERK1/2. Furthermore, the simultaneous administration of both drugs synergistically enhanced the inhibitory effect on cell proliferation. Our study suggests that use of these drugs may represent a novel approach to treat CCA through drug repositioning.

Assessing multilevel barriers to hydroxyurea adherence in youth with sickle cell disease using pharmacy-based refill records.

BACKGROUND: Suboptimal medication adherence is common across youth with chronic health conditions and may contribute to health disparities and adverse health outcomes, especially in underserved communities. METHODS: Using pharmacy prescription records and guided by the World Health Organization Multidimensional Adherence Model, we examined patient-, treatment-, and health system-related factors that may affect hydroxyurea adherence in 72 youth with sickle cell disease (SCD), 10-18 years who had participated in the multisite "Hydroxyurea Adherence for Personal Best in SCD" (HABIT) feasibility (6 months) and efficacy (12 months) trials. Pharmacy data were collected from the year prior to study entry through the duration of each trial. We also examined hydroxyurea dose at baseline, prescribing patterns (hydroxyurea formulation and dose prescribed), quantity of hydroxyurea dispensed, and number of daily capsules/tablets prescribed. Data were analyzed using descriptive statistics. RESULTS: On average, youth were prescribed 1095 ± 402 mg hydroxyurea per day, requiring ingestion of 3 or more capsules for 39.4% of youth. Frequently identified potential barriers were complex medication regimens in which dose of hydroxyurea differed by day of week (47.2%); receipt of an inadequate (< 30 days) supply of hydroxyurea from the pharmacy ≥ 3 times during record collection period (29.2%); and prescription of hydroxyurea suspension suggesting problems swallowing capsules (22.2%). In this sample, most youth were exclusively prescribed 500 mg capsules (62.5%), which was associated with complex medication regimens (RR 3.0, 95% CI 1.4-6.7). Potential barriers were common, occurred at all levels and are potentially modifiable with targeted interventions at the treatment- and health system-related levels.

The impact of sickle cell disease and its treatment on ovarian reserve in reproductive-aged Black women.

We compared serum anti-Mullerian hormone (AMH) levels in women with sickle cell disease (SCD) (n = 152) to those of Black comparison women (n = 128) between the ages of 20 and 45 years and evaluated the impact of hydroxyurea (HU) and iron overload on ovarian reserve in those with SCD. SCD treatment was abstracted from medical records. Linear regression models were fit to examine the relationship between log(AMH) and SCD, adjusting for age. The analysis was repeated to account for HU use (current, previous, never) and iron overload (ferritin ≥1000 ng/mL vs. <1000 ng/mL). AMH estimates among women with SCD were lower than those among comparison women (2.23, 95% confidence interval [CI] 1.80-2.76 vs. 4.12, 95% CI 3.11-5.45, respectively). Women with SCD who were currently using HU had 63% lower (95% CI 43-76) AMH values than comparison women; those with SCD with prior or no HU use also had lower AMH estimates than comparison women, but the difference was less pronounced. There were no differences in predicted AMH values among women with SCD for those with and without iron overload. Women with SCD and low AMH may have a shorter reproductive window and may benefit from referral to a reproductive specialist.

Feasibility of a clinic-based, multicomponent hydroxyurea adherence intervention for adolescents and young adults with sickle cell disease.

Despite the effectiveness of hydroxyurea, adherence remains low for adolescents and young adults (AYA) living with sickle cell disease (SCD). This study evaluated the feasibility, acceptability, and initial efficacy of a clinic-based, multicomponent (e.g., storytelling, problem solving) intervention with 20 AYA living with SCD. Results found that adherence significantly improved from intervention to follow-up 1 [t(19) = -2.213, p = .039]. AYA also were generally satisfied with the intervention. These findings, although promising, should be replicated on a larger scale.

Hydroxyurea maintains working memory function in pediatric sickle cell disease.

Sickle cell disease (SCD) decreases the oxygen-carrying capacity of red blood cells. Children with SCD have reduced/restricted cerebral blood flow, resulting in neurocognitive deficits. Hydroxyurea is the standard treatment for SCD; however, whether hydroxyurea influences such effects is unclear. A key area of SCD-associated neurocognitive impairment is working memory, which is implicated in other cognitive and academic skills. The neural correlates of working memory can be tested using n-back tasks. We analyzed functional magnetic resonance imaging (fMRI) data of patients with SCD (20 hydroxyurea-treated patients and 11 controls, aged 7-18 years) while they performed n-back tasks. Blood-oxygenation level-dependent (BOLD) signals were assessed during working memory processing at 2 time points: before hydroxyurea treatment and ~1 year after treatment was initiated. Neurocognitive measures were also assessed at both time points. Our results suggested that working memory was stable in the treated group. We observed a treatment-by-time interaction in the right cuneus and angular gyrus for the 2- >0-back contrast. Searchlight-pattern classification of the 2 time points of the 2-back tasks identified greater changes in the pattern and magnitude of BOLD signals, especially in the posterior regions of the brain, in the control group than in the treated group. In the control group at 1-year follow-up, 2-back BOLD signals increased across time points in several clusters (e.g., right inferior temporal lobe, right angular gyrus). We hypothesize that these changes resulted from increased cognitive effort during working memory processing in the absence of hydroxyurea. In the treated group, 0- to 2-back BOLD signals in the right angular gyrus and left cuneus increased continuously with increasing working memory load, potentially related to a broader dynamic range in response to task difficulty and cognitive effort. These findings suggest that hydroxyurea treatment helps maintain working memory function in SCD.

Replication stress response in fission yeast differentially depends on maintaining proper levels of Srs2 helicase and Rrp1, Rrp2 DNA translocases.

Homologous recombination is a key process that governs the stability of eukaryotic genomes during DNA replication and repair. Multiple auxiliary factors regulate the choice of homologous recombination pathway in response to different types of replication stress. Using Schizosaccharomyces pombe we have previously suggested the role of DNA translocases Rrp1 and Rrp2, together with Srs2 helicase, in the common synthesis-dependent strand annealing sub-pathway of homologous recombination. Here we show that all three proteins are important for completion of replication after hydroxyurea exposure and provide data comparing the effect of overproduction of Srs2 with Rrp1 and Rrp2. We demonstrate that Srs2 localises to rDNA region and is required for proper replication of rDNA arrays. Upregulation of Srs2 protein levels leads to enhanced replication stress, chromosome instability and viability loss, as previously reported for Rrp1 and Rrp2. Interestingly, our data suggests that dysregulation of Srs2, Rrp1 and Rrp2 protein levels differentially affects checkpoint response: overproduction of Srs2 activates simultaneously DNA damage and replication stress response checkpoints, while cells overproducing Rrp1 mainly launch DNA damage checkpoint. On the other hand, upregulation of Rrp2 primarily leads to replication stress response checkpoint activation. Overall, we propose that Srs2, Rrp1 and Rrp2 have important and at least partially independent functions in the maintenance of distinct difficult to replicate regions of the genome.

Reviewing the impact of hydroxyurea on DNA methylation and its potential clinical implications in sickle cell disease.

Hydroxyurea (HU) is the most common drug therapy for sickle cell disease (SCD). The clinical benefits of HU derive from its upregulation of fetal hemoglobin (HbF), which reduces aggregation of the mutated sickle hemoglobin protein (HbS) and reduces SCD symptoms and complications. However, some individuals do not respond to HU, or stop responding over time. Unfortunately, current understanding of the mechanism of action of HU is limited, hindering the ability of clinicians to identify those patients who will respond to HU and to optimize treatment for those receiving HU. Given that epigenetic modifications are essential to erythropoiesis and HbF expression, we hypothesize that some effects of HU may be mediated by epigenetic modifications, specifically DNA methylation. However, few studies have investigated this possibility and the effects of HU on DNA methylation remain relatively understudied. In this review, we discuss the evidence linking HU treatment to DNA methylation changes and associated gene expression changes, with an emphasis on studies that were performed in individuals with SCD. Overall, although HU can affect DNA methylation, research on these changes and their clinical effects remains limited. Further study is likely to contribute to our understanding of hematopoiesis and benefit patients suffering from SCD.

Suppressors of Blm-deficiency identify three novel proteins that facilitate DNA repair in Ustilago maydis.

To identify new molecular components of the Brh2-governed homologous recombination (HR)-network in the highly radiation-resistant fungus Ustilago maydis, we undertook a genetic screen for suppressors of blm-KR hydroxyurea (HU)-sensitivity. Twenty DNA-damage sensitive mutants were obtained, three of which showing slow-growth phenotypes. Focusing on the "normally" growing candidates we identified five mutations, two in previously well-defined genes (Rec2 and Rad51) and the remaining three in completely uncharacterized genes (named Rec3, Bls9 and Zdr1). A common feature among these novel factors is their prominent role in DNA repair. Rec3 contains the P-loop NTPase domain which is most similar to that found in U. maydis Rec2 protein, and like Rec2, Rec3 plays critical roles in induced allelic recombination, is crucial for completion of meiosis, and with regard to DNA repair Δrec3 and Δrec2 are epistatic to one another. Importantly, overexpression of Brh2 in Δrec3 can effectively restore DNA-damage resistance, indicating a close functional connection between Brh2 and Rec3. The Bls9 does not seem to have any convincing domains that would give a clue as to its function. Nevertheless, we present evidence that, besides being involved in DNA-repair, Bls9 is also necessary for HR between chromosome homologs. Moreover, Δbls9 showed epistasis with Δbrh2 with respect to killing by DNA-damaging agents. Both, Rec3 and Bls9, play an important role in protecting the genome from mutations. Zdr1 is Cys2-His2 zinc finger (C2H2-ZF) protein, whose loss does not cause a detectable change in HR. Also, the functions of both Bls9 and Zdr1 genes are dispensable in meiosis and sporulation. However, Zdr1 appears to have overlapping activities with Blm and Mus81 in protecting the organism from methyl methanesulfonate- and diepoxybutane-induced DNA-damage. Finally, while deletion of Rec3 and Zdr1 can suppress HU-sensitivity of blm-KR, Δgen1, and Δmus81 mutants, interestingly loss of Bls9 does not rescue HU-sensitivity of Δgen1.

KBM-mediated interactions with KU80 promote cellular resistance to DNA replication stress in CHO cells.

The KU heterodimer (KU70/80) is rapidly recruited to DNA double-strand breaks (DSBs) to regulate their processing and repair. Previous work has revealed that the amino-terminal von Willebrand-like (vWA-like) domain in KU80 harbours a conserved hydrophobic pocket that interacts with a short peptide motif known as the Ku-binding motif (KBM). The KBM is present in a variety of DNA repair proteins such as APLF, CYREN, and Werner protein (WRN). Here, to investigate the importance of KBM-mediated protein-protein interactions for KU80 function, we employed KU80-deficient Chinese Hamster Ovary (Xrs-6) cells transfected with RFP-tagged wild-type human KU80 or KU80 harbouring a mutant vWA-like domain (KU80L68R). Surprisingly, while mutant RFP-KU80L68R largely or entirely restored NHEJ efficiency and radiation resistance in KU80-deficient Xrs-6 cells, it failed to restore cellular resistance to DNA replication stress induced by camptothecin (CPT) or hydroxyurea (HU). Moreover, KU80-deficient Xrs-6 cells expressing RFP-KU80L68R accumulated pan-nuclear γH2AX in an S/G2-phase-dependent manner following treatment with CPT or HU, suggesting that the binding of KU80 to one or more KBM-containing proteins is required for the processing and/or repair of DNA ends that arise during DNA replication stress. Consistent with this idea, depletion of WRN helicase/exonuclease recapitulated the CPT-induced γH2AX phenotype, and did so epistatically with mutation of the KU80 vWA-like domain. These data identify a role for the KBM-binding by KU80 in the response and resistance of CHO cells to arrested and/or collapsed DNA replication forks, and implicate the KBM-mediated interaction of KU80 with WRN as a critical effector of this role.

Clinical methemoglobinemia secondary to administration of hydroxyurea at therapeutic doses in a dog.

Methemoglobinemia secondary to administration of hydroxyurea is only reported in veterinary medicine as a result of accidental ingestion of high doses, and once at therapeutic dose in human medicine. A 2.5-year-old female spayed mixed breed dog was presented for acute signs of neurologic disease and diagnosed with severe erythrocytosis without an identified underlying cause, leading to suspicion of polycythemia vera. The dog was managed with phlebotomies, supportive care, and administration of hydroxyurea. Within 2 h of administration of hydroxyurea (37 mg/kg) administration, respiratory distress with cyanosis, and methemoglobinemia developed. Signs resolved within 24 h but recurred after a second administration of lower dosage of hydroxyurea (17 mg/kg) 20 days later. The dog remained asymptomatic except for mild cyanosis but was humanely euthanized for lack of relevant improvement of signs of neurologic disease. This case report documents the repeated occurrence of methemoglobinemia in a dog after administration of hydroxyurea at therapeutic doses.

Characteristic effect of hydroxyurea on the higher-order structure of DNA and gene expression.

Hydroxyurea (HU; hydroxycarbamide) is a chemotherapy medication used to treat various types of cancer and other diseases such as sickle cell anemia. HU inhibits DNA synthesis by targeting ribonucleotide reductase (RNR). Recent studies have suggested that HU also causes oxidative stress in living systems. In the present study, we investigated if HU could directly affect the activity and/or conformation of DNA. We measured in vitro gene expression in the presence of HU by adapting a cell-free luciferase assay. HU exhibited a bimodal effect on gene expression, where promotion or inhibition were observed at lower or higher concentrations (mM range), respectively. Using atomic force microscopy (AFM), the higher-order structure of DNA was revealed to be partially-thick with kinked-branching structures after HU was added. An elongated coil conformation was observed by AFM in the absence of HU. Single DNA molecules in bulk aqueous solution under fluctuating Brownian motion were imaged by fluorescence microscopy (FM). Both spring and damping constants, mechanical properties of DNA, increased when HU was added. These experimental investigations indicate that HU directly interacts with DNA and provide new insights into how HU acts as a chemotherapeutic agent and targets other diseases.

Effects of hydroxyurea on fertility in male and female sickle cell disease patients. A systemic review and meta-analysis.

BACKGROUND: Evidence supports the benefits of hydroxyurea (HU) in adults with sickle cell disease (SCD), but reservations remain due to long-term concerns of fertility. Retrospective analysis of clinical records of SCD patients (haemoglobin SS genotype) have identified gender-related differences in disease progression. This could inform risk stratification during SCD at diagnosis with the possibility to guide therapeutic decisions. METHODS: This systemic review and meta-analysis evaluated fertility parameters in both children (aged ≥ 6 years) and adults with SCD receiving HU therapy. Studies were sourced from PubMed and EMBASE from inception to July 2023. A total of 160 potentially relevant articles were identified. RESULTS: Four studies were included that evaluated the effects of HU on sperm parameters in males. A further 4 studies assessed anti-mullerian hormone (AMH) levels and ovarian reserves in females. Differences from baseline values were used to identify compromised fertility. Amongst males, HU treatment negatively impacted the concentration of spermatozoa (MD = -15.48 million/mL; 95% CI: [-20.69, -10.26]; p< 0.001), which continued following treatment cessation (MD = -20.09 million/mL; 95% CI: [-38.78, -1.40]; P = 0.04). HU treatment also led to lower total sperm counts (MD = -105.87 million; 95% CI: [-140.61, -71.13]; P< 0.001) which persisted after treatment (MD = -53.05 million; 95% CI: [-104.96, -1.14]; P = 0.05). Sperm volume, initial forward motility and morphology were unaffected by HU treatment. In females, HU treatment decreased the mean AMH levels 1.83 (95% CI [1.42, 2.56]. A total of 18.2.% patients treated with HU showed reduced ovarian reserves. INTERPRETATION & CONCLUSIONS: This systemic review and meta-analysis suggest that the use of HU for SCD impacts seminal fluid parameters in males and can diminish AMH levels and ovarian reserves in females.

Study protocol for ADHERE (Applying Directly observed therapy to HydroxyurEa to Realize Effectiveness): Using small business partnerships to deliver a scalable and novel hydroxyurea adherence solution to youth with sickle cell disease.

Sickle cell disease (SCD) is an inherited blood disorder that affects approximately 100,000 Americans, primarily from underrepresented racial minority populations, and results in costly, multi-organ complications. Hydroxyurea, the primary disease-modifying therapy for SCD, is effective at reducing most complications; however, adherence to hydroxyurea remains suboptimal and is the primary barrier to clinical effectiveness. Video directly observed therapy (VDOT) has shown promise as an adherence-promoting intervention for hydroxyurea, yet previous VDOT trials were limited by high attrition from gaps in technology access, use of unvalidated adherence measures, and healthcare system limitations of delivering VDOT to patients. As such, we fostered a small business partnership to compare VDOT for hydroxyurea to attention control to address previous shortcomings, promote equitable trial participation, and maximize scalability. VDOT will be administered by Scene Health (formerly emocha Health) and adherence monitoring will be performed using a novel electronic adherence monitor developed to meet the unique needs of the target population. Adolescent and young adult patients as well as caregivers of younger patients (<11 years of age) will be recruited. In addition to visit incentives, all participants will be offered a smartphone with a data plan to ensure all participants have equal opportunity to complete study activities. The primary objectives of this pilot, multi-center, randomized controlled trial (RCT) are to assess retention and sustained engagement and to explore needs and preferences for longer-term adherence monitoring and interventions. This RCT is registered with the National Institutes of Health (NCT06264700). Findings will inform a future efficacy RCT applying VDOT to hydroxyurea to address adherence gaps and improve outcomes within this vulnerable population.

Effect of Hydroxyurea on Morphology, Proliferation, and Protein Expression on Taenia crassiceps WFU Strain.

Flatworms are known for their remarkable regenerative ability, one which depends on totipotent cells known as germinative cells in cestodes. Depletion of germinative cells with hydroxyurea (HU) affects the regeneration of the parasite. Here, we studied the reduction and recovery of germinative cells in T. crassiceps cysticerci after HU treatment (25 mM and 40 mM of HU for 6 days) through in vitro assays. Viability and morphological changes were evaluated. The recovery of cysticerci's mobility and morphology was evaluated at 3 and 6 days, after 6 days of treatment. The number of proliferative cells was evaluated using EdU. Our results show morphological changes in the size, shape, and number of evaginated cysticerci at the 40 mM dose. The mobility of cysticerci was lower after 6 days of HU treatment at both concentrations. On days 3 and 6 of recovery after 25 mM of HU treatment, a partial recovery of the proliferative cells was observed. Proteomic and Gene Ontology analyses identified modifications in protein groups related to DNA binding, DNA damage, glycolytic enzymes, cytoskeleton, skeletal muscle, and RNA binding.

Sickle cell disease and infertility risks: implications for counseling and care of affected girls and women.

INTRODUCTION: Sickle cell disease (SCD), its treatments and cures present infertility risks. Fertility counseling is broadly indicated for affected girls and women and fertility preservation may appeal to some. Several streams of evidence suggest that the reproductive lifespan of women with SCD is reduced. Pregnancy is associated with high miscarriage rates. There are enduring questions about the effects of highly effective hydroxyurea treatment on female fertility. Current conditioning regimens for gene therapy or hematopoietic stem cell transplant are gonadotoxic. Fertility preservation methods exist as non-experimental standards of care for girls and women. Clinicians are challenged to overcome multifactorial barriers to incorporate fertility counseling and fertility preservation care into routine SCD care. AREAS COVERED: Here we provide a narrative review of existing evidence regarding fertility and infertility risks in girls and women with SCD and consider counseling implications of existing evidence. EXPERT OPINION: Addressing fertility for girls and women with SCD requires engaging concerns that emerge across the lifespan, acknowledging uncertainty and identifying barriers to care, some of which may be insurmountable without public policy changes. The contemporary SCD care paradigm can offer transformative SCD treatments alongside comprehensive counselling that addresses fertility risks and fertility preservation opportunities.

Azathioprine/hydroxyurea preconditioning prior to nonmyeloablative matched sibling donor hematopoietic stem cell transplantation in adults with sickle cell disease: A prospective observational cohort study.

Nonmyeloablative, matched sibling donor hematopoietic stem cell transplantation with alemtuzumab/total body irradiation (TBI) conditioning is a curative therapy with low toxicity for adults with sickle cell disease (SCD). However, relatively low donor chimerism levels and graft rejection remain important challenges. We hypothesized that adding azathioprine/hydroxyurea preconditioning will improve donor chimerism levels and reduce graft failure rate. In this prospective cohort study, we enrolled consecutive adult patients with SCD undergoing matched sibling donor transplantation at the Amsterdam UMC. Patients received azathioprine 150 mg/day and hydroxyurea 25 mg/kg/day for 3 months prior to alemtuzumab 1 mg/kg and 300 cGy TBI conditioning. Twenty patients with SCD (median age 26 years [range 19-49], 13 females) were transplanted. Median follow-up was 46.0 months (IQR 21.8-57.9). One-year overall survival and event-free survival (graft failure or death) were both 95% (95% confidence interval 86-100). Mean donor myeloid and T-cell chimerism 1-year post-transplant were 95.2% (SD ±10.6) and 67.3% (±15.3), respectively. One patient (5%) experienced graft failure without autologous regeneration, resulting in infections and death. All other patients had a corrected SCD phenotype and were able to discontinue sirolimus. Three patients were successfully treated with alemtuzumab (1 mg/kg) after the transplant because of declining donor chimerism and cytopenias to revert impending graft rejection. Toxicity was mostly related to sirolimus and alemtuzumab. One patient developed steroid-responsive grade II intestinal acute graft-versus-host disease. Collectively, preconditioning with azathioprine/hydroxyurea prior to nonmyeloablative matched sibling donor transplantation resulted in excellent event-free survival and robust donor T-cell chimerism, enabling the successful withdrawal of sirolimus. ClinicalTrials.gov: NCT05249452.

Hydroxyurea dose optimisation for children with sickle cell anaemia in sub-Saharan Africa (REACH): extended follow-up of a multicentre, open-label, phase 1/2 trial.

BACKGROUND: Realizing Effectiveness Across Continents with Hydroxyurea (REACH) is an open-label non-randomised trial of hydroxyurea (hydroxycarbamide) in children with sickle cell anaemia in sub-Saharan Africa. The short-term results of REACH on safety, feasibility, and effectiveness of hydroxyurea were published previously. In this paper we report results from extended hydroxyurea treatment in the REACH cohort up to 8 years. METHODS: In this open-label, non-randomised, phase 1/2 trial, participants were recruited from four clinical sites in Kilifi, Kenya; Mbale, Uganda; Luanda, Angola; and Kinshasa, Democratic Republic of Congo. Eligible children were 1-10 years old with documented haemoglobin SS or haemoglobin Sß zero thalassaemia, weighing at least 10 kg. Participants received fixed-dose hydroxyurea of 17.5 (±2.5) mg/kg per day for 6 months (fixed-dose phase), followed by 6 months of dose escalation (2·5-5·0 mg/kg increments every 8 weeks) as tolerated, up to 20-35 mg/kg per day (maximum tolerated dose; MTD), defined as mild myelosuppression. After the MTD was reached, hydroxyurea dosing was optimised for each participant on the basis of changes in bodyweight and laboratory values over time (MTD with optimisation phase). After completion of the first 12 months, children with an acceptable toxicity profile and favourable responses were given the opportunity to continue hydroxyurea until the age of 18 years. The safety and feasibility results after 3 years has been reported previously. Here, haematological responses, clinical events, and toxicity rates were compared across the dosing phases (fixed-dose hydroxyurea vs MTD with optimisation phase) as protocol-specified outcomes. REACH is registered on ClinicalTrials.gov (NCT01966731) and is ongoing. FINDINGS: We enrolled 635 children between July 4, 2014, and Nov 11, 2016. 606 children were given hydroxyurea and 522 (86%; 266 [51%] boys and 256 [49%] girls) received treatment for a median of 93 months (IQR 84-97) with 4340 patient-years of treatment. The current (Oct 5, 2023) mean dose is 28·2 (SD 5·2) mg/kg per day with an increased mean haemoglobin concentration (7·3 [SD 1·1] g/dL at baseline to 8·5 [1·5] g/dL) and mean fetal haemoglobin level (10·9% [SD 6·8] to 23·3% [9·5]) and decreased absolute neutrophil count (6·8 [3·0] × 109 cells per L to 3·6 [2·2] × 109 cells per L). Incidence rate ratios (IRR) comparing MTD with fixed-dose hydroxyurea indicate decreased vaso-occlusive episodes (0·60; 95% CI 0·52-0·70; p<0·0001), acute chest syndrome events (0·21; 0·13-0·33; p<0·0001), recurrent stroke events (0·27; 0·07-1·06; p=0·061), malaria infections (0·58; 0·46-0·72; p<0·0001), non-malarial infections (0·52; 0·46-0·58; p<0·0001), serious adverse events (0·42; 0·27-0·67; p<0·0001), and death (0·70; 0·25-1·97; p=0·50). Dose-limiting toxicity rates were similar between the fixed-dose (24·1 per 100 patient-years) and MTD phases (23·2 per 100 patient-years; 0·97; 0·70-1·35; p=0·86). Grade 3 and 4 adverse events were infrequent (18·5 per 100 patient-years) and included malaria infection, non-malarial infections, vaso-occlusive pain, and acute chest syndrome. Serious adverse events were uncommon (3·6 per 100 patient-years) and included malaria infections, parvovirus-associated anaemia, sepsis, and stroke, with no treatment-related deaths. INTERPRETATION: Hydroxyurea dose escalation to MTD with dose optimisation significantly improved clinical responses and treatment outcomes, without increasing toxicities in children with sickle cell anaemia in sub-Saharan Africa. FUNDING: US National Heart, Lung, and Blood Institute and Cincinnati Children's Research Foundation.

Clinical Practice Patterns in Sickle Cell Disease Treatment: Disease-modifying and Potentially Curative Therapies.

Therapeutic options for sickle cell disease (SCD) have increased recently as well as the development of updated national guidelines. It is not known how these options are being offered or to what degree guidelines are incorporated into clinical practice. This study aimed to describe practice patterns for pediatric hematologists regarding the use of disease-modifying and potentially curative therapies for SCD. A 9-section, cross-sectional electronic survey was disseminated during a 3-month period via SurveyMonkey, to members of the American Society of Pediatric Hematology/Oncology Hemoglobinopathy Special Interest Group (ASPHO HSIG). A total of 88 physician members of the ASPHO HSIG were surveyed. Ninety percent of respondents (72/80) start hydroxyurea routinely in patients with HbSS and HbSß 0 thalassemia, regardless of disease severity. Laboratory monitoring was recommended every 3 months for stable dosing in 63.8% (51/80). New therapies were recommended for patients on hydroxyurea who were still experiencing SCD complications: L-glutamine 68.5% (37/54) or crizanlizumab 93.1% (54/58). Voxelotor was recommended for patients on hydroxyurea with low hemoglobin in 65.1% (43/66) of cases. Matched sibling transplant was considered for any disease severity by 55.1% (38/69). Gene therapy trials are offered on-site by 29% (20/69). Our study demonstrated the enhanced utilization of hydroxyurea while revealing the unexplored potential of other disease-modifying therapies in SCD. These findings underscore the importance of continued knowledge acquisition about the long-term efficacy of new medical therapies and addressing barriers to the use of proven therapies and guide the development of future studies of optimal SCD management.