Background: Sickle cell disease (SCD) is the most common inherited blood disorder in the United States, caused by polymerization of a mutated form of hemoglobin (HbS). HbS can form long polymers inside red blood cells (RBCs) that affect RBC shape and adhesion, resulting in RBC destruction, acute and chronic pain, inflammation and cumulative organ damage. SCD-101 is a botanical drug with in vitro and in vivo anti-sickling activity. The mechanism by which SCD-101 inhibits sickling is unknown; however, it does not bind directly to Hb or change the affinity of Hb for oxygen. We recently completed a dose-escalation clinical study of SCD-101 in adults with sickle cell disease in steady state, and other clinical studies are on-going. Methods: The initial prospective, open-label, Phase 1B dose-escalation study enrolled homozygous (SS) sickle cell patients and S/beta0 thalassemia patients ages 18-55 with baseline Hb levels 6.0-9.0 g/dL and hemoglobin F ≤10%. Admission within 30 days, transfusion within 90 days, and hydroxyurea within 6 months were exclusions. SCD-101 was dosed orally for 28-days with a 14-day follow-up visit. Doses administered during the dose escalation study were 550 mg, 1100 mg, 2200 mg and 4400 mg BID. The primary endpoint was safety, and the secondary endpoints were mean change in Hb, Hct, percent reticulocytes, LDH, indirect bilirubin, CRP, PROMIS fatigue questionnaire score, and percent circulating partially oxygenated sickle cells (POSCs) in venous whole blood fixed in 2% glutaraldehyde without exposure to air. A repeat cohort study is ongoing with dose adjusted to 2750 mg TID, a 6-minute walk test added as a functional endpoint and measurement of inflammatory cytokines by ELISA to explore the effect of SCD-101 on inflammation. Results: As of August 4, 2016, 26 patients with sickle cell disease have been enrolled, 20 patients have completed the 28-day dose-escalation study and 3 were discontinued before receiving their first dose of SCD-101. Three patients are enrolled in the 28-day repeat cohort study. There have been no dose reductions or interruptions due to drug-related effects. SCD-101 was generally well-tolerated with mild-moderate bloating and flatulence at the highest dose on a BID schedule in the dose-escalation study, which were not observed with a TID schedule in the repeat cohort study. There were no significant changes in safety laboratory tests and no significant changes in hemoglobin, hematocrit, LDH, unconjugated bilirubin, or reticulocytes. No significant changes were observed in renal, hepatic or other safety chemistries or electrocardiograms. SCD-101 participants treated at higher doses reported a decrease in chronic pain and fatigue after 7-14 days, which returned post-treatment when measured on the 14-day follow-up visit. Participants at the two highest doses reported an increase in exercise capacity and an improvement in sleep. Two participants with ankle ulcers, enrolled at the two highest doses, showed improved healing. Analysis of peripheral blood smears revealed an improvement in the shape of circulating RBCs. There was no change in inflammatory cytokines in the first 7 days in the repeat cohort study, though the Day 28 data may show a different result. Conclusions: SCD-101 is a promising new drug for the treatment of sickle cell disease, based on the results from the studies reported here. SCD-101 was well tolerated over an 8-fold dose range, and dose-dependent anti-sickling effects on RBC were observed, though without significant changes in hemolysis. Clinical benefits included reduced chronic pain and fatigue, improved sleep and improved ulcer healing. While the identity of the active substance(s) in SCD-101 and the mechanism(s) of action are unknown, SCD-101 has a direct anti-sickling effect on RBCs, compatible with an intracellular or membrane effect on RBCs. We hypothesize that the observed effects could be explained by increased vascular flow or increased oxygen delivery or a reduction in inflammation. A placebo-controlled crossover study will be completed in 2016 including a 6-minute walk test as a primary clinical endpoint, and a multi-site Phase 2 study is planned for 2017. As a botanical drug, SCD-101 may be a useful treatment for sickle cell disease worldwide. Disclosures Swift: Global Blood Therapeutics: Equity Ownership; Mast Therapeutics: Equity Ownership; SCD Development: Employment, Equity Ownership.
Patients with sickle cell disease have high morbidity and healthcare utilization due to repeated painful crises. Some coexisting conditions which cause pain similar to sickle cell disease may go undiagnosed in these patients. We report two adults with concurrent hyperparathyroidism who experienced significant improvement in sickle cell pain following parathyroidectomy thereby pointing to hyperparathyroidism as the principal causative factor for their pain. Meticulous evaluation for parathyroid disorders can be rewarding in sickle cell disease.
Hematopoietic stem cell transplant (HSCT) is the only cure for patients with sickle cell disease (SCD). Although most SCD patients experience progressive end-organ damage and shortened lifespans, not all patients follow the same disease course, tempo, or outcome. Therefore, the dilemma facing physicians is weighing the selection of patients and timing for the procedure against donor type and transplant-related mortality and morbidity that go up with increasing age. On the other hand, the dilemma facing the patients and families is how acceptable HSCT that carries some mortality risks to them. We have analyzed the chronic conditions due to SCD in 449 patients to determine whether SCD-related multiple chronic conditions (MCC) can be risk-stratified to identify the group of patients predicted to not only have shortened lifespans but also functional limitation and poor quality of life so that these at-risk patients can be offered HSCT early and before MCC develops. We identified that the age of onset of the first SCD-related chronic conditions strongly predicted for the risks for disease-related MCC. SCD patients who suffered their first disease-related chronic condition before age 30 years developed MCC at a rate of 19.1 times faster than those at a later age. These patients are therefore high-risk patients and should be offered HSCT early in the course of their disease before multiple organ damage intervenes, even if matched-related donors are not available. This patient selection and timing approach provides a forum for an easy-to-understand and real-time discussion, including the choice of donor type, with SCD patients and families when considering HSCT.
The association between Moyamoya syndrome (MMS) and sickle cell disease (SCD) has been wellestablished in pediatric populations; however, limited literature exists documenting the characteristics and management of MMS in adult SCD patients. Studies have indicated the role of endovascular management in secondary stroke prevention for pediatric populations, with no current guidelines available for adult populations. Here, we describe a unique case of MMS in a 30-year-old patient with SCD and incidental protein S deficiency. Our unique case highlights a patient at high risk for neurosurgical intervention due to her hypercoagulable state who has benefitted from medical management. We also discuss current literature for the prevention of secondary cerebral vascular events and the role of further studies involving adult populations with MMS and SCD.
Rheumatoid arthritis (RA) can occur concurrently in patients with sickle cell disease (SCD). Both conditions can have similar musculoskeletal symptoms during painful exacerbations. SCD tends to be frequently labelled as the causative factor of painful events by both patients and providers alike. It is important to distinguish between these two conditions causing painful exacerbations to guide treatment plans. Our review of literature showed that the concurrent presentation of RA and SCD is not well described. We present a case series of eight patients with concurrent RA and SCD. We conducted a retrospective review of their charts to make observations about differences in musculoskeletal symptoms, biomarkers and radiological changes. Generally, RA affects smaller joints compared to SCD which affects larger joints. Radiological differences include bone infarcts and avascular necrosis in SCD versus erosive arthritis in RA. In terms of biomarkers, we are better guided using C-reactive protein (CRP) in conjunction with lactate dehydrogenase (LDH). Our case series demonstrates certain indicators which help make a clearer distinction between the two usually painful conditions.
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