An Open-label, Multicenter Phase 1 Trial to Evaluate the Safety, Pharmacokinetics and Pharmacodynamics of Splicing Modulator H3B-8800 for Subjects With Myelodysplastic Syndromes, Acute Myeloid Leukemia, and Chronic Myelomonocytic Leukemia ENCORE-MDS

What's the purpose of this trial?

A Phase 1, an Open-label, Multicenter Phase 1 Trial to Evaluate the Safety, Pharmacokinetics and Pharmacodynamics of Splicing Modulator H3B-8800 (RVT-2001) for Subjects With Myelodysplastic Syndromes, Acute Myeloid Leukemia, and Chronic Myelomonocytic Leukemia

This trial is currently open and accepting patients.

What will happen during the trial?

You may be able to join this trial if you:

The following criteria is a partial list of reasons why patients may be eligible to participate in this clinical trial. Further evaluation with a medical professional is required.

Inclusion Criteria:

1. Confirmed diagnosis of MDS, CMML, or AML.

For the MDS Expansion cohort, participants must be lower-risk MDS, defined as low or intermediate-1 risk categorization per International Prognostic Scoring System (IPSS) criteria that carries a missense SF3B1 mutation.

For the Dose Optimization cohort, participants must be transfusion-dependent, lower-risk MDS, defined as very-low to intermediate risk categorization per IPSS-R criteria that carries a missense SF3B1 mutation.
2. Participants must meet the following criteria relevant to their specific diagnosis:

A. Participants with higher-risk MDS/CMML must be intolerant of hypomethylating agents (HMAs) or not have responded to 4 treatment cycles of decitabine or 6 treatment cycles of azacitidine, or must have progressed at any point after initiation of an HMA.

B. For the Dose Escalation portion, participants with lower-risk MDS/CMML must be transfusion-dependent for red blood cells or platelets.

For the MDS expansion cohort, lower risk MDS participants must be RBC transfusion dependent according to IWG 2006 criteria and must also have failed erythropoiesis stimulating agents (ESA) or have serum erythropoietin (EPO) levels greater than (\>) 500 units per liter (U/L).

C. For the Dose Optimization cohort, lower-risk MDS participants must be RBC transfusion-dependent at baseline defined as ≥3 RBC units (concentrates) in 16-weeks in at least 2 transfusion episodes prior to the first dose of H3B-8800 (RVT-2001) and must also have failed ESA or have serum EPO levels \> 500 U/L. Any ESA use should be discontinued ≥6 weeks prior to enrollment.

D. Participants with AML must either refuse or not be considered candidates for intensive induction chemotherapy using consensus criteria for defining such participants.

E. Participants with CMML must have been treated with at least one prior therapy (hydroxyurea or a hypomethylating agent \[HMA\]).
3. Eastern Cooperative Oncology Group (ECOG) performance score of 0-2.
4. For MDS expansion and Dose optimization cohorts - absolute neutrophil count (ANC) greater than or equal to (\>=) 500/ microliter (mcL) (0.5\*10\^9/L).
5. For expansion and Dose optimization cohorts- platelet count \>50,000/mcL (50\*10\^9/L).
6. For Dose-optimization cohort: No prior HMA or lenalidomide in participants with lower-risk MDS.
7. Adequate baseline organ function.

Exclusion Criteria:

1. Diagnosis of a core binding factor leukemia (t(8;21), t(16;16) or inv(16)). Diagnosis of acute promyelocytic leukemia (t(15;17))
2. Participants are deemed candidate for hematopoietic stem cell transplants at the time of enrollment (for AML participants only).
3. Known prior or current retinal or optic nerve disease (example, Retinitis Pigmentosa, diabetic retinopathy, optic neuritis) not stable for at least 6 months.
4. History of clinically significant, uncorrected vitamin B12 or folate deficiency.

Additional Trial Information

Phase 1

Enrollment: 200 patients (estimated)

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Published Results

Results of a Clinical Trial of H3B-8800, a Splicing Modulator, in Patients with Myelodysplastic Syndromes (MDS), Acute Myeloid Leukemia (AML) or Chronic Myelomonocytic Leukemia (CMML)

November 13, 2019

As of June 16th, 2019, 84 patients were enrolled at 24 centers in the US and Europe. Dose ranged from 1-40 mg among 65 patients on schedule I, while 19 patients were enrolled with dose ranging from 7-20 mg on schedule II. The patient population included AML (n=38), CMML (n=4), HR-MDS (n=20), LR-MDS (n=21) and 1 MDS with unknown risk level. Most patients (88%) had spliceosome mutations of interest. The most common mutations were in SRSF2 (p.P95H in 17, p.P95L in 9, p.P95_R102Del in 4), SF3B1 (p.K700E in 11, p.R625C in 4), and U2AF1 (p.Q157P in 6, p.S34F in 4).

Patients remained on treatment from 7 to 819 days; 25 patients (30%) had time on treatment greater than 180 days, 20% more than 1 year and 2% over 2 years. The median therapy duration for LR-CMML/MDS, HR-CMML/MDS, and AML patients were 216, 62, and 47 days respectively. Most observed treatment related treatment-emergent adverse events (TEAEs) were Grade 1 or 2. The most common treatment-related (as judged by the investigator, >10% frequency) TEAEs in the patients treated on schedule I were diarrhea (75%), nausea (37%), fatigue (28%) and vomiting (27%). The most common treatment-related TEAEs in the patients treated on schedule II were diarrhea (68%), vomiting (42%), QTc prolongation (21%), nausea (16%), and fatigue (16%). The most common dose limiting toxicity was prolongation of the QTcF interval >500 msec (n=2, 40 mg on schedule I and n=1, 20 mg on schedule II, all ≥Grade 3) and bradycardia without other arrhythmias (n=1, 14 mg on schedule II, ≥Grade 3). No ophthalmic AEs were observed; 1 patient (LR-MDS) experienced durable marrow aplasia. The maximum tolerated dose (MTD) has not been confirmed for either Schedule I or Schedule II.

PK analysis indicates that H3B-8800 is rapidly absorbed and exhibits dose-proportional increase in plasma exposure. Consistent dose-dependent target engagement (i.e., alteration in mature mRNA transcripts) was observed in blood mononuclear cells from patients enrolled in the 2 mg up to 40 mg dose cohorts on both schedules. Despite this splicing modulation, no objective complete responses (CR) or partial responses (PR) meeting International Working Group criteria were observed. One patient with CMML had a durable platelet response that began in Cycle 1 and persisted through Cycle 13. Nine red blood cell (RBC) transfusion-dependent patients with MDS or CMML and 2 patients with AML did not require RBC transfusions for ≥8 weeks (up to 28 weeks) while on study. One platelet transfusion-dependent patient with LR-MDS did not require platelet transfusions for ≥8 weeks.

Trial Locations

All Trial Locations

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Arizona Oncology Associates

Tucson, AZ

Open and Accepting


City of Hope Comprehensive Cancer Center Beckman Research Institute

Duarte, CA

Open and Accepting


Rocky Mountain Cancer Centers (Aurora) Aurora

Aurora, CO

Open and Accepting


Mayo Clinic (Jacksonville)

Jacksonville, FL

Open and Accepting


Massachusetts General Hospital

Boston, MA

Open and Accepting

Beth Israel Deaconess Medical Center

Boston, MA

Open and Accepting

Dana-Farber Cancer Institute (Main)

Boston, MA

Open and Accepting


Barbara Ann Karmanos Cancer Institute Wayne State University

Detroit, MI

Open and Accepting


Mayo Clinic (Rochester)

Rochester, MN

Open and Accepting


Oncology Associates of Oregon

Eugene, OR

Open and Accepting


Texas Oncology (Austin Midtown) Austin Midtown

Austin, TX

Open and Accepting

MD Anderson Cancer Center The University of Texas

Houston, TX

Open and Accepting


Virginia Cancer Specialists

Fairfax, VA

Open and Accepting
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