In this protocol, the investigators propose to evaluate the biochemical effects of imatinib on sickle red blood cells (RBCs). Patients will be administered imatinib mesylate orally following the guidelines previously established for use of imatinib in other disorders. The biochemical effects of imatinib on sickle RBCs will be examined, including changes in their levels of band 3 tyrosine phosphorylation and the abundances of RBC-derived microparticles in their blood. In addition, the patients will be monitored for symptoms of sickle cell disease (SCD). The investigators expect band 3 tyrosine phosphorylation to decrease dramatically in patients treated with imatinib. The investigators also anticipate a reduction in the numbers of RBC-derived microparticles in circulation (quantitated by assaying the number of glycophorin A positive microparticles in peripheral blood samples by flow cytometry. Most importantly, the investigators expect to see a reduction in the frequency of vaso-occlusive crises, and possibly acute chest syndrome and utilization of opioids. The study duration is planned as 6 months in order to provide adequate time for potential change in the primary endpoints (e.g. percent irreversibly sickled cells).
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
7
The starting dose for subjects will be 340 mg/m2/day with a maximum dose of 600 mg daily. Patients will receive Imatinib orally once daily for 6 months.
Riley Hospital for Children at IU Health
Indianapolis, Indiana, United States
Cincinnati Children's Hospital
Cincinnati, Ohio, United States
Changes in Biochemical Effects - Band 3 Phosphorylation
Percent change in Band 3 Phosphorylation tested in red blood cells. Band 3 is a protein found on the membrane of red blood cells.
Time frame: Change from baseline Band 3 Phosphorylation at 7 months
Change in Amount of Microparticles Released From Red Blood Cells
Change in Microparticles released from red blood cells. Microparticles are small vesicles released from red blood cells during aging, stress, or other types of damage that contain various proteins from inside the red blood cell, as well as from its membrane.
Time frame: change from baseline microparticle release at 7 months
Change in Percent Irreversibly Sickled Cells
Functional RBCs is analyzed by two components, one of which is percent irreversibly sickled cells. The percent of irreversibly sickled cells is measure by ektacytometry. Red blood cells that sickle and then cannot revert back to its normal shape are considered irreversibly sickled, increasing the likelihood of adhesion to vessel walls, as well as breakdown or hemolysis. Understanding the point of susceptibility of sickling helps us at what partial pressure of oxygen the red blood cell will sickle. The higher the partial pressure, the more resistant the red blood cell is to sickling/breakdown.
Time frame: Change from baseline of percent irreversibly sickled cells at 7 months
Change in Point of Susceptibility to Sickling by OxygenScan
Functional RBCs is analyzed by two components, one of which is Change in Point of Susceptibility to Sickling. This is measured by OxygenScan. The point of susceptibility of sickling shows at what partial pressure of oxygen (mmHg) the red blood cell will sickle. The higher the partial pressure, the more resistant the red blood cell is to sickling/breakdown.
Time frame: Change from baseline of point of susceptibility of sickling at 7 months
Number of Instances of Vaso-occlusive Crisis (VOC)
Defined as an acute episode of pain lasting greater than 24 hours, with no medically determined cause other than a vaso-occlusive event that resulted in treatment with oral or parenteral opiate agents and/or parenteral nonsteroidal anti-inflammatory agents. Degree of pain was measured by the standard numerical pain scale (0 being little to no pain, 10 being the worst pain).
Time frame: Assessed monthly from treatment start up to 7 months
Number of Instances of Acute Chest Syndrome (ACS)
Defined as respiratory distress (hypoxia, shortness of breath, chest pain, tachypnea) with evidence of an infiltrate on chest x-ray Measured with clinical evaluation.
Time frame: Assessed monthly from treatment start up to 7 months
Opioid Use
Defined as oral opioid use. Oral use will be documented in pain diary by patient/guardian and reviewed at each visit.
Time frame: Assessed monthly from treatment start up to 7 months
Number of Hospitalizations
Defined as an emergency room or clinic visit resulting in an inpatient admission or observation for a sickle cell-related event (e.g. vaso-occlusive pain, acute chest syndrome, etc).
Time frame: Assessed monthly from treatment start up to 7 months
Assessment of Toxicities of Imatinib in Patients With Sickle Cell Anemia
Assessment of toxicities based on clinical and laboratory evaluation
Time frame: Assessed monthly from treatment start up to 7 months
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