Skip to content

Novel BET Inhibitor PLX51107 for Steroid-Refractory Acute GVHD

A Single Arm, Open Label, Phase 1b/2 Study of Novel BET Inhibitor PLX51107 for Steroid-Refractory Acute GVHD

Status
Terminated
Phases
Phase 1Phase 2
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT04910152
Enrollment
2
Registered
2021-06-02
Start date
2022-04-19
Completion date
2023-09-28
Last updated
2025-01-28

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Acute Graft Versus Host Disease, Steroid Refractory Graft Versus Host Disease

Brief summary

This phase Ib/II trial studies the side effects of PLX51107 in treating steroid-refractory acute graft versus host disease (GVHD). PLX51107 is a novel, potent non-benzodiazepine structured small molecule BET inhibitor with a unique binding mode selective for BRD4 inhibition and a more tolerable side effect profile. PLX51107 may work better in treating steroid-refractory acute GVHD.

Detailed description

PRIMARY OBJECTIVES: I. To evaluate the safety and tolerability of BRD4 inhibitor PLX51107 (PLX51107) as a single agent for allogeneic transplant recipients with steroid-refractory acute graft versus host disease (GVHD). II. To assess the pharmacokinetic (PK) and pharmacodynamic (PD) of orally administered PLX51107 in steroid-refractory acute GVHD patients. SECONDARY OBJECTIVE: I. To evaluate the preliminary efficacy of PLX51107 in steroid-refractory acute GVHD patients. OUTLINE: Patients receive BRD4 inhibitor PLX51107 orally (PO) once daily (QD) on days 1-28. Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up at 30 days and then up to 6 months.

Interventions

Sponsors

Plexxikon
CollaboratorINDUSTRY
National Cancer Institute (NCI)
CollaboratorNIH
Hannah Choe, MD
Lead SponsorOTHER

Study design

Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

* Age \>= 18 years at the time of signing informed consent * Steroid-refractory acute GVHD as defined as progression of acute (a)GvHD within 3-5 days of therapy onset with \>= 2 mg/kg/day of prednisone equivalent OR failure to improve within 5-7 days of treatment initiation with \> 1-2 mg/kg/day of prednisone equivalent OR incomplete response after more than 28 days of immunosuppressive treatment including steroids * Recipients of ablative and reduced-intensity conditioning regimens * Recipients of human leukocyte antigen (HLA)-matched related and unrelated, 1-allele mismatched, haploidentical, or umbilical cord blood donor grafts * Prior lines of therapy for treatment of steroid-refractory acute GVHD are allowed. However, exposure to investigational therapies for the treatment of GVHD must be \> 14 days or 5 half-lives (whichever is shorter) of first administration of study drug. For patients treated with ruxolitinib for the treatment of acute GVHD, ruxolitinib must be discontinued by at least one day prior to initiation of PLX51107 * Eastern Cooperative Oncology Group (ECOG) performance status =\< 3 * Absolute neutrophil count \>= 1.0 x 10\^9/L for 3 consecutive days). Use of growth factor support is allowed * Platelet count \>= 50 x 10\^9/L without transfusion support for 2 consecutive days * Women of child-bearing potential must have a negative serum pregnancy test at Screening and must agree to use an effective form of contraception from the time of the negative pregnancy test up to 6 months after the last dose of study drug. Effective forms of contraception include abstinence, hormonal contraceptive in conjunction with a barrier method, or a double barrier method. Women of non-child-bearing potential may be included if they are either surgically sterile or have been postmenopausal for \>= 1 year * Fertile men must agree to use an effective method of birth control during the study and for up to 6 months after the last dose of study drug

Exclusion criteria

* Prior exposure to a bromodomain inhibitor * Evidence of chronic GVHD * Evidence of active relapse of disease * Exposure to other investigational or anti-cancer therapies (not for GVHD) within 28 days or 5 half-lives (whichever is shorter) of first administration of study drug * Active, uncontrolled bacterial, fungal, or viral infection * Known or suspected allergy to the study drug * Clinically significant cardiac disease, defined as: * Clinically significant cardiac arrhythmias, including bradyarrhythmia, and/or a need for anti-arrhythmic therapy (excluding beta blockers or digoxin). Individuals with controlled atrial fibrillation are not excluded * Fridericia-corrected QT interval (QTcF) \>= 450 ms (male) or \>= 470 ms (female) at screening * History of clinically significant cardiac disease or congestive heart failure greater than New York Heart Association Class II. Subjects must not have unstable angina (angina symptoms at rest) or experienced either new-onset angina within the last 3 months or myocardial infarction (MI) within the last 6 months unless it was due to the underlying disease and there has been appropriate revascularization. Individuals with ambiguous troponin levels that are not diagnostic of an MI should be discussed with the principal investigator (PI) prior to enrollment * Arterial or venous thrombotic or embolic events such as cerebrovascular accident (including transient ischemic attacks), deep vein thrombosis, or pulmonary embolism within the 6 months before start of study medication (except for catheter-related venous thrombosis * Inability to take oral medication or significant nausea and vomiting, malabsorption, or significant small bowel resection that, in the opinion of the Investigator, would preclude adequate absorption * Active thrombotic microangiopathy (TMA) * Women who are either pregnant or breast feeding * Measured or calculated (Cockcroft-Gault formula) creatinine clearance (CrCl) \< 45 mL/min * Prothrombin time or international normalized ratio \> 1.5 x upper limit of normal (ULN) * Activated partial thromboplastin time \> 1.5 x ULN * Requiring mechanical ventilation or vasopressor support * Subject is participating in any other therapeutic clinical study (observational or registry studies are allowed)

Design outcomes

Primary

MeasureTime frameDescription
Maximum Tolerated Dose (MTD)Up to 28 days
Incidence of Adverse Events Grade 3 and 4Up to 6 monthsAdverse events by grade will be summarized. The occurrence of grade 3+ adverse events according to Common Terminology Criteria for Adverse Events will be summarized as well. Adverse events will initially be reviewed regardless of attribution, but also according to whether adverse events are possibly, probably, or definitely related to treatment.

Secondary

MeasureTime frameDescription
Complete Response (CR)At day 28The proportion of CR with a 95% confidence interval will be reported, assuming a binomial distribution.
Overall Response RateAt day 28The overall response rate (ORR) will include CR and partial response (PR), while mixed response (MR) and no response (NR) will be classified as no response. The ORR will be similarly analyzed as CR.
Non-relapse Mortality (NRM)From the date of starting PLX51107 to date of death with the competing risk as death due to disease, assessed at 6 monthsThe cumulative incidence curve accounting for competing risks will be generated to estimate the cumulative incidence of NRM rate at 6 months. The comparison in NRM between patient subgroups may be explored graphically.

Other

MeasureTime frameDescription
Pharmacokinetics (PK) AnalysisUp to 6 monthsPharmacokinetics (PK) for target exposure of AUC0-24 8300 ng•hr/mL

Countries

United States

Participant flow

Participants by arm

ArmCount
Treatment for aGVHD (BRD4 Inhibitor PLX51107)
Patients receive BRD4 inhibitor PLX51107 PO QD on days 1-28. Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity. BRD4 Inhibitor PLX51107: Given PO
2
Total2

Baseline characteristics

CharacteristicTreatment for aGVHD (BRD4 Inhibitor PLX51107)
Age, Categorical
<=18 years
0 Participants
Age, Categorical
>=65 years
0 Participants
Age, Categorical
Between 18 and 65 years
2 Participants
Ethnicity (NIH/OMB)
Hispanic or Latino
0 Participants
Ethnicity (NIH/OMB)
Not Hispanic or Latino
2 Participants
Ethnicity (NIH/OMB)
Unknown or Not Reported
0 Participants
Race (NIH/OMB)
American Indian or Alaska Native
0 Participants
Race (NIH/OMB)
Asian
0 Participants
Race (NIH/OMB)
Black or African American
0 Participants
Race (NIH/OMB)
More than one race
0 Participants
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
0 Participants
Race (NIH/OMB)
Unknown or Not Reported
0 Participants
Race (NIH/OMB)
White
2 Participants
Region of Enrollment
United States
2 participants
Sex: Female, Male
Female
0 Participants
Sex: Female, Male
Male
2 Participants

Adverse events

Event typeEG000
affected / at risk
deaths
Total, all-cause mortality
1 / 1
other
Total, other adverse events
1 / 1
serious
Total, serious adverse events
1 / 1

Outcome results

Primary

Incidence of Adverse Events Grade 3 and 4

Adverse events by grade will be summarized. The occurrence of grade 3+ adverse events according to Common Terminology Criteria for Adverse Events will be summarized as well. Adverse events will initially be reviewed regardless of attribution, but also according to whether adverse events are possibly, probably, or definitely related to treatment.

Time frame: Up to 6 months

ArmMeasureGroupValue (NUMBER)
Treatment for aGVHD (BRD4 Inhibitor PLX51107)Incidence of Adverse Events Grade 3 and 4Grade 2 Adverse Events : Neutrophil Count Decreased1 participants
Treatment for aGVHD (BRD4 Inhibitor PLX51107)Incidence of Adverse Events Grade 3 and 4Grade 3 Adverse Events : Anemia1 participants
Treatment for aGVHD (BRD4 Inhibitor PLX51107)Incidence of Adverse Events Grade 3 and 4Grade 3 Adverse Events : Creatinine Increased1 participants
Treatment for aGVHD (BRD4 Inhibitor PLX51107)Incidence of Adverse Events Grade 3 and 4Grade 1 Adverse Events : Bloating1 participants
Treatment for aGVHD (BRD4 Inhibitor PLX51107)Incidence of Adverse Events Grade 3 and 4Grade 1 Adverse Events : Confusion1 participants
Treatment for aGVHD (BRD4 Inhibitor PLX51107)Incidence of Adverse Events Grade 3 and 4Grade 1 Adverse Events : Dyspnea1 participants
Treatment for aGVHD (BRD4 Inhibitor PLX51107)Incidence of Adverse Events Grade 3 and 4Grade 2 Adverse Events : Creatinine Increased1 participants
Treatment for aGVHD (BRD4 Inhibitor PLX51107)Incidence of Adverse Events Grade 3 and 4Grade 3 Adverse Events : Neutrophil Count Decreased1 participants
Treatment for aGVHD (BRD4 Inhibitor PLX51107)Incidence of Adverse Events Grade 3 and 4Grade 3 Adverse Events : Adult Respiratory Distress Syndromre1 participants
Treatment for aGVHD (BRD4 Inhibitor PLX51107)Incidence of Adverse Events Grade 3 and 4Grade 3 Adverse Events : Upper Gastrointestinal Hemorrhage1 participants
Treatment for aGVHD (BRD4 Inhibitor PLX51107)Incidence of Adverse Events Grade 3 and 4Grade 3 Adverse Events : White Blood Cell Decreased1 participants
Treatment for aGVHD (BRD4 Inhibitor PLX51107)Incidence of Adverse Events Grade 3 and 4Grade 4 Adverse Events : Platelet Count Decreased1 participants
Treatment for aGVHD (BRD4 Inhibitor PLX51107)Incidence of Adverse Events Grade 3 and 4Grade 4 Adverse Events : White Blood Cell Decreased1 participants
Primary

Maximum Tolerated Dose (MTD)

Time frame: Up to 28 days

Population: Maximum tolerated dose was not able to be determined due to low accrual number.

Secondary

Complete Response (CR)

The proportion of CR with a 95% confidence interval will be reported, assuming a binomial distribution.

Time frame: At day 28

Population: Complete response data was not collected due to low accrual numbers

Secondary

Non-relapse Mortality (NRM)

The cumulative incidence curve accounting for competing risks will be generated to estimate the cumulative incidence of NRM rate at 6 months. The comparison in NRM between patient subgroups may be explored graphically.

Time frame: From the date of starting PLX51107 to date of death with the competing risk as death due to disease, assessed at 6 months

Population: NRM data was not collected due to low accrual numbers

Secondary

Overall Response Rate

The overall response rate (ORR) will include CR and partial response (PR), while mixed response (MR) and no response (NR) will be classified as no response. The ORR will be similarly analyzed as CR.

Time frame: At day 28

Population: Overall response data was not collected due to low accrual numbers.

Other Pre-specified

Pharmacokinetics (PK) Analysis

Pharmacokinetics (PK) for target exposure of AUC0-24 8300 ng•hr/mL

Time frame: Up to 6 months

Population: PK analysis data was not collected due to low accrual numbers

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026