A Phase II Study Using Fostamatinib to Treat Post-Hematopoietic Stem Cell Transplant Immune-Mediated Cytopenias

• Status: Not yet recruiting
• Trial end date: 2026-04-01
• Target enrollment: 0
• Participant gender: All

Summary

Study Description:

This open label phase II trial is designed to evaluate the efficacy of fostamatinib in the treatment of post-transplant cytopenias as assessed by hematologic improvement in anemia and/or thrombocytopenia following a 12-week treatment course. Patients who respond to the 12-week treatment course on this single arm study are eligible and have the option to enroll on the extended access trial.

Objectives:

The primary objective is to assess efficacy of fostamatinib for stable hematologic recovery during post-hematopoietic stem cell transplant immune mediated anemia and/or thrombocytopenia.

The secondary objective is to assess efficacy of fostamatinib for clinically-relevant outcomes in post-hematopoietic stem cell transplant patients.

The exploratory objective is to evaluate changes in serologic markers that may be associated with cytopenias while on treatment to identify key elements for fostamatinib response.

Endpoints:

Primary endpoints:

The proportion of subjects with hematologic recovery that is stable, defined as improvement documented in 2 consecutive available readings at least 2 weeks apart, without recent blood product transfusion support in the past 7 days.

-Hematologic recovery is defined as:

--Hemoglobin >=10 g/dL (or at least >=2 g/dL above baseline) in subjects enrolled with posttransplant anemia. In subjects with symptomatic anemia, a hemoglobin increase of at least >=2 g/dL above baseline is required

OR

--Platelets >= 50 x 10^9/L (or at least >=20 x 10^9/L above baseline) in subjects enrolled with posttransplant thrombocytopenia

OR

--Both of the above criteria in subjects with posttransplant Evan s syndrome

Secondary endpoints:

-Proportion of subjects who achieve objective hematologic recovery within the 12-week treatment course defined as:

--Hemoglobin >=9 g/dL (or at least >=1 g/dL above baseline) in subjects enrolled with anemia or at least >=1 g/dL above baseline in subjects with symptomatic anemia

OR

--Platelets >= 30 x 109/L (or at least >=10 x 109/L above baseline) in subjects enrolled with thrombocytopenia

OR

-- Either of the above criteria in subjects with Evan s syndrome

• Average weekly requirement of transfused blood component or growth factor requirement (total units of PRBC or Platelets/week, total dose of growth factor/week) by week 12, compared to the week prior to the start of the study drug.

• Change in corticosteroid dose over time, measured by median daily weight-based prednisone-equivalent corticosteroid dose in a week, from week 1 to week 12

• Change in other immunosuppressant dose over time, measured by median daily dose of the immunosuppressant in a week, from week 1 to week 12

• Number of patients who achieved >=50% steroid dose reduction by week 12 compared to week 1

• Incidence and severity of cGVHD according to 2014 NIH Consensus Criteria, at baseline before the initiation of treatment, and at week 12

Exploratory endpoints:

• Absolute percentage change in B cell chimerism pre-treatment, vs weeks 4 and 12.

• cPRA change in the preformed HLA antibodies before and after treatment in subjects with thrombocytopenia or Evan s syndrome

• Percent MFI change of preformed HLA antibodies before and after treatment. This applies for antibodies with an MFI >1,000.

• Anti-RBC alloantibody titer change in patients with hemolytic anemia before and after treatment

• Assessment of serial cytokines pre-treatment and weeks 4 and 12. Cytokines include CRP, IL-1, IL-2, IL-6, IFN gamma, TNF alpha, EPO and TPO

• Immunoglobulin level changes pre-treatment, and weeks 4 and 12.

• Absolute reticulocyte count, lactate dehydrogenase, haptoglobin changes pre-treatment, and at each biweekly study visit, in patients with anemia or Evan s syndrome

• Change in the weekly rate and severity of bleeding according to the total score of the ITP-Bleeding Scale (IBLS), from week -1 (one week before the start of the study drug) to week 12, in subjects with thrombocytopenia or Evan s syndrome

• Phase: Phase 2
• Accepts Healthy Volunteers?: No

Details

• Lead Sponsor: National Heart, Lung, and Blood Institute (NHLBI)

Criteria

• INCLUSION CRITERIA:

• Ages 18-75 years inclusive

• Ability to comprehend the investigational nature of the study and provide informed consent

• Female patients of reproductive potential agree to avoid pregnancy through abstinence or the use two forms of highly effective birth control during and for 1 month after the last study treatment and agree not to donate eggs during this time

• male patients of reproductive potential agree to avoid pregnancy of a partner through abstinence or the use two forms of highly effective birth control during and for 1 month after the last study treatment and agree not to donate sperm during this time.

• Diagnosis of an immune mediated cytopenia (anemia and/or thrombocytopenia) in a patient that either:

• Failed or relapsed after at least one line of therapy including steroids, IVIG, TPO mimetics, rituximab, azathioprine, cyclophosphamide, cyclosporine, tacrolimus, danazol, vincristine, ESA or splenectomy

• Or remains transfusion dependent (>=1 transfusion(s)/2 weeks)

• Or is steroid dependent

• Subjects are >=60 days post-allogeneic transplant with:

• Thrombocytopenia, defined as average platelets count <30 x 10^9/L for 3 consecutive available readings at least 2 weeks apart, after other cell lines have engrafted, with no counts >40 x 10^9/L unless from rescue transfusions. Subjects failed at least one line of therapy outlined above with a clinical diagnosis of immune mediated thrombocytopenia.

• Anemia, transfusion dependent, or defined as hemoglobin <=9 g/dL for 3 consecutive available readings at least 2 weeks apart, after other cell lines have engrafted OR if hemoglobin 9-10 g/dL, subject must have symptomatic anemia or ongoing treatment for immune hemolytic anemia that have failed at least one line of therapy outlined above. Symptomatic anemia is defined as anemia with fatigue, weakness, shortness of breath, palpitations/fast heartbeat, lightheadedness, and/or chest pain, and these symptoms are attributed to anemia. Laboratory evaluation are recommended but not required for the diagnosis, such as a positive DAT, low haptoglobinindirect bilirubin > upper limit of normal (ULN), or lactate dehydrogenase (LDH) >ULN.

• Subjects must test negative for HIV, HBV, and HCV by standard serologic tests within the previous six months

• Subjects on other standard of care therapeutic regimens for GVHD or cytopenias should be on a stable dose of medication (no change >=25%) for at least 15 days prior to enrollment.

• Patients with a history of hypertension should be maintained on a stable antihypertensive regimen and with controlled blood pressure (Systolic blood pressure < 140 mmHg and diastolic blood pressure <90 mmHg) for at least one week prior to enrollment.

• Peripheral blood or bone marrow T-cell chimerism >=50% donor cells

• Immune mediated anemia in subjects with auto or alloantibodies identified due to ABO or non-ABO mismatch transplant, or thrombocytopenia due to identified HLA/HPA antibody. Other causes of immune mediated cytopenias include clinically diagnosed (with or without serologic confirmation) idiopathic thrombocytopenic purpura or autoimmune hemolytic anemia. Subjects with cytopenias attributable to GVHD will be included. Subjects with idiopathic immune mediated cytopenias can also be included. Subjects with evidence for graft rejection per the investigator's opinion ARE NOT eligible for treatment.

Steroid dependence is defined as inability to tolerate a corticosteroid taper after demonstrating a response to an initial corticosteroid dose (typically 1-2 mg/kg/day). Patients will meet our definition of steroid dependence if their cytopenias relapse or progress before achieving a 50% decrease in the initial corticosteroid dose and/or are unable to have their steroid dose tapered to a dose of less than 20 mg/day of prednisone.

EXCLUSION CRITERIA:

• Severe psychiatric illness or mental deficiency sufficient to make making informed consent impossible

• Positive pregnancy test for women of childbearing age within 1 week or being actively lactating

• Immune mediated cytopenia responsive to the standard of care treatment

• Immune mediated cytopenia due to other autoimmune causes, such as systemic lupus erythrocytosis, chronic lymphocytic leukemia

• Non-immune mediated cytopenias. Etiologies including, but not limited to, cytopenias due to HIV infection, lymphoproliferative disorders, myelodysplasia/acute leukemia, drug-induced thrombocytopenia, thrombotic microangiopathies, acute bleeding, consumptive coagulopathy, fever, infections leading to cytopenia, medications induced cytopenias, thrombotic microangiopathies (disseminated intravascular coagulation), splenomegaly or hemophagocytic lymphohistiophagocytosis, relapse of primary disease.

• Patients with neutropenia, defined as absolute neutrophil count <=1.0 x 10^9/L, will be excluded

• Uncontrolled hypertension (systolic blood pressure >=140mmHg or diastolic blood pressure >=90mmHg)

• ALT or AST >=3 times the upper limit of normal, or direct bilirubin >=2 times the upper limit of normal

• Patients who have a history of medical disorders, that in the investigator's opinion, could affect the conduct of the study or the absorption, metabolism or excretion of the study drug are excluded.

• Patients with lymphoma/chronic lymphocytic leukemia, hepatitis, or HIV associated with ITP/wAIHA

• Patients with evidence of graft rejection (based on clinical suspicion supported by BM biopsy data and/or chimerism studies and/or MLR)

• Subjects recently treated (within 30 days) with cytokine-targeting biologics (anti-TNF, IL6) or Bcell or plasma-cell depleting antibody.

• Other cancers except that for which the transplant was done < 2 years before study entry, except non-melanoma skin cancer or carcinoma in situ of the uterine cervix or breast