Hypothesis

Efficient unloading of oxygen to regions of high metabolic demand requires a healthy microvasculature to sense local oxygen tension and regulate flow, accordingly. In sickle cell disease patients, the investigators have demonstrated oxygen supply-demand mismatch, or SDM, in proportion to anemia severity. SDM occurs in both the peripheral circulation and the brain, and four characteristics: 1) Hyperemia beyond expected for the level of anemia, 2) Corresponding loss of vascular dilatory reserve, 3) Impaired oxygen unloading to the tissues, and 4) Tissue hypoxia. In sickle cell disease, red blood cell (RBC) and white blood cell (WBC) adhere to vascular endothelium triggering transient or irreversible microvascular damage as well as releasing vasoactive substances that contribute to microvascular dysregulation. The investigators postulate that ongoing microvascular damage/dysregulation in the setting of increased total blood flow contributes to SDM. The investigators believe SEG101, by lowering RBC and WBC adhesion to the microvasculature, will improve SDM and tissue oxygenation.

Objectives

• Primary - The investigators will test whether SEG101 improves SDM in patients with sickle cell anemia by measuring the change in tissue oxygenation measured by near infrared spectroscopy (NIRS).
• Secondary/Exploratory - The investigators will identify end-organ disease and whether improvement of SDM by SEG101 occurs in patients with sickle cell anemia.

Objectives Primary Objectives 1. The investigators will test whether SEG101 improves Supply-Demand Matching in patients with sickle cell anemia measured by the change in tissue oxygenation by NIRS.

a) This is measured as a percent oxyhemoglobin saturation (%).

Secondary Objectives

1. Secondary measures to assess the change in tissue oxygenation will be

   1. In the somatic peripheral circulation - microcirculatory perfusion at rest and post-ischemia by laser doppler, venous oxygen saturation by venous blood gas and co-oximetry, and vasoconstriction by plethysmography.
   2. In the cerebral circulation - blood flow by arterial spin labeling, function brain MRI and response to CO2 challenge, sagittal sinus saturation by TRUST and tissue oxygen extraction by asymmetric spin echo.
   3. In the pulmonary vasculature - Pulmonary circulation - sleep study pulse oximetry for oxygenation and vasoconstriction by plethysmography, tricuspid regurgitant jet velocity (TRV) with echo markers of diastolic function to balance pulmonary vascular vs. left heart etiology of TRV.

2. Determine the relationship between SDM biomarkers and hemoglobin level (anemia).

   a) Hemoglobin and hematocrit for interaction between SDM and anemia

3. The investigators will determine whether low SDM predicts end-organ function in sickle cell anemia as compared to controls. These endpoints will be organ specific associations:

   a) eGFR and urinalysis for kidney, myocardial fibrosis, systolic/diastolic heart function, troponin and NT-pro-BNP

4. Relationship between markers of cellular adhesion, oxidative stress and inflammation, soluble VCAM and soluble P-selection.

   a) Interaction of SDM with soluble markers of adhesion and inflammation.

5. The investigators will identify interactions based on age and sex.

   a) Sex and gender related differences will act as covariates for all measures because many cardiovascular metrics have significant sex differences

6. Clinical Outcome Measures

   1. VOC history and prospective VOC burden.
   2. Blood pressure and ECG abnormalities/arrhythmias

Overall Design: The study will be performed at a single large sickle cell disease Centers of Excellence, Children's Hospital of Los Angeles in California, in 20 patients with sickle cell disease who will receive SEG101 therapy and 10 sickle cell anemia subjects who will not receive therapy. Full inclusion and exclusion criteria are defined in the human subjects section but sickle cell disease patients will be 16 years of age, or older (to be able to cooperate with the MRI examination without anesthesia), and free from hospitalization or emergency room visit for one month prior to the study. Entire cohort will be gender balanced.

The effects of SEG101 will be assessed in 20 nontransfused SCD subjects. Figure 3 summarizes the study schema. After comprehensive baseline assessment one month prior the time of study initiation, patients will be started on 5mg/kg of body weight to be initiated at week 1 with follow up dosing at week 3 and week 7 then q4weeks until week 23, which will be the last dose given (7 total doses). Safety laboratories will be drawn at each infusion visit. This will not be a randomized control trial. There will be a follow up phone call the day after receiving the medication. Comprehensive blood and vascular testing will be repeated at 3 and 6 months of treatment.

A total of 10 SCD subjects will be recruited from the hematology clinic at CHLA, generating a similar distribution of SS and Sß0 hemoglobin. The participants will be studied twice, once at the beginning of the study, time 0, and once at the end of study, after 6 months. The participants will undergo the same cerebral, peripheral and cardiopulmonary testing procedures as the patients undergoing therapy. The participants will also have monthly phone calls to determine clinical outcomes such as crisis frequency, medication use, hospitalizations and other pertinent clinical findings that may arise.

This is a non-randomized, open label intervention pilot study evaluating the effect of SEG101 on SDM in patients with sickle cell disease (SCD). The investigators plan to enroll 20 patients with SCD, who will receive SEG101. The investigators will also enroll 10 SCD subjects who will undergo all testing procedures but will not receive SEG101 treatment. The investigators will assess three vascular beds: 1. Peripheral circulation of the hand/arm (primary), 2. Brain (primary), and 3. Heart (exploratory).

Specific measures of SDM are summarized in Table 1. While SDM cannot currently be assessed in the heart, the heart represents a critical target for end organ dysfunction (Aim 2) because of its high metabolic demands and predisposition to microvascular damage.

Patient Population

Study Population - Patients with sickle cell anemia

Interruption or discontinuation of treatment

Patients may voluntarily withdraw from the study or be dropped from it at the discretion of the investigator at any time.

Treatment/Drug Administration

This is an open label study of SEG101. All patients will have peripheral SDM assessment in the arm/hand prior to and immediately following their initiation of SEG101 therapy. MRI exams will be performed prior to initiation of SEG101 therapy at the initial study visit but will not have immediate post therapy studies. Patients will have two repeat studies at 3-months and 6-months (end of study). The participants will receive SEG101 at 5mg/kg of body weight by intravenous infusion Qmonth and this will constitute "treatment".

Expected side effects

Previous research has demonstrated efficacy of SEG101 intravenous administration at 5mg/kg of body weight to decrease frequency of painful crisis. This is an FDA approved medication for prevention of painful crisis in SCD. In the Phase 2 clinical trial, the most common side effects noted were nausea (18%), arthralgia (18%), headache (17%), extremity pain (17%), back pain (15%), urinary tract infection (14%), musculoskeletal pain (12%), upper respiratory infection (11%), pyrexia (11%), diarrhea (11%), pruritis (8%), vomiting (8%), and chest pain (2%). These were derived from the SUSTAIN Phase 2 clinical trial.

Other medication use, standard of care

Standard of care therapies will not be stopped or changed. The investigators will encourage all practitioners to maintain pre-study medications throughout the study period, however, the investigators will not require it. The primary physician can adjust other medications as the participants determine necessary to their care. The SS patient's hydroxyurea use will be recorded in order to test a physiologic response (changes in brain and peripheral blood flow) and control for hydroxyurea effect. Use or non-use of hydroxyurea is not a contraindication to participating in this study, however, patients will need verbal assent from their primary hematologist to participate. HU therapy will need to be at the clinically tolerated dose for at least 6 months prior to starting the SEG101 therapy. HU therapy will not be adjusted or initiated during the study period and will not be considered a "treatment" for study purposes.

Inclusion Criteria (Both Patient Groups - 1. SCD on SEG101 and 2. SCD not receiving SEG101)

• We will enroll only SS and Sß0 sickle cell disease patients
• Both male and female will be included.
• Our population of sickle cell disease is 90% African American and 10% Hispanic, therefore, our study population will reflect that distribution of ethnicity.
• Informed consent from legal guardian and/or patient
• Able to participate without needing sedation for MRI scan
• Age at least 16 years

Exclusion Criteria (Both Patient Groups - 1. SCD on SEG101 and 2. SCD not receiving SEG101)

• Any pain crisis requiring an ER visit and/or admission to the hospital and/or required parenteral pain medication in the previous 4 weeks.
• Any acute transfusion in the previous 4 weeks
• Need for chronic transfusion therapy
• Any known chronic illness that in the judgment of the investigator may compromise subject safety or data integrity. These include but are not limited to rheumatologic disorders, malignancy, severe asthma, chronic hepatic or renal insufficiency.
• Known pregnancy
• Seizure disorder
• Inability to cooperate with MRI examinations
• Contraindication to Crizanlizumab

undecided