Valemetostat Tosylate (DS-3201b) Phase 2 Study in Relapsed or Refractory Adult T-cell Leukemia/Lymphoma

Study Overview
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Brief Summary
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This Phase 2 study will be conducted to assess the efficacy and safety of valemetostat tosylate (DS-3201b) in participants with relapsed or refractory adult T-cell leukemia/lymphoma (r/r ATL).

Official Title
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A Phase 2, Multicenter, Open-label, Single-arm Study of Valemetostat Tosylate (DS-3201b) in Patients With Relapsed or Refractory Adult T-cell Leukemia/Lymphoma

Conditions
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Adult T-cell Leukemia/Lymphoma

Intervention / Treatment
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* Drug: Valemetostat Tosylate


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Participants with relapsed or refractory adult T-cell leukemia/lymphoma (ATL) who have history of treatment with mogamulizumab or are mogamulizumab intolerant, contraindication after treatment with at least 1 medication regimen Aged ≥20 years or older at the time of signing the informed consent Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0-2 At least 1 evaluable lesion Participants who have defined laboratory criteria Life expectancy ≥ 3 months Exclusion Criteria: A presence of central nervous system involvement at the time of screening tests Have poorly controlled complication (eg. chronic congestive heart failure, unstable angina ≥ Grade 3 neuropathy QT interval corrected using Fridericia's method (QTcF) >470 ms Has an uncontrolled infection Participants who use corticosteroids over 10 mg/day Receipt of allogeneic hematopoietic stem cell transplantation History of, or concurrent, malignant tumors

Ages Eligible for Study
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Minimum Age: 20 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: DS-3201b<br> | Drug: Valemetostat Tosylate<br>* Once a day, 200 mg, oral administration<br>* Other names: DS-3201b;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Overall response rate (ORR) assessed by central evaluation organization | The percentage of participants who were assessed for best overall response, who achieved complete remission (CR), complete remission, unconfirmed (CRu) or partial remission (PR) by central evaluation organization. | Through the end of the study (within approximately 5 years) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Overall response rate (ORR) assessed by investigator | The percentage of participants who were assessed for best overall response, who achieved CR, CRu, or PR by investigator. | Through the end of the study (within approximately 5 years) | 
| Best response per tumor lesions | Best response in target lesions (nodal or extranodal lesions), peripheral blood lesions, and skin lesions. | Through the end of the study (within approximately 5 years) | 
| Complete remission rate (CR rate) | The percentage of participants who were assessed for best overall response, who achieved CR or CRu. | Through the end of the study (within approximately 5 years) | 
| Tumor control rate (TCR) | The percentage of participants who were assessed for best overall response, who achieved CR, CRu, PR or stable disease (SD). | Through the end of the study (within approximately 5 years) | 
| Time to response (TTR) | Period from the first day of DS-3201b dose to the first day of CR, CRu, or PR | Through the end of the study (within approximately 5 years) | 
| Duration of response (DOR) | Period from first CR, CRu, or PR to residual disease/progressive disease (RD/PD) or death. | Through the end of the study (within approximately 5 years) | 
| Progression-free survival (PFS) | Period from the first day of DS-3201b dose to the day of RD/PD or death. | Through the end of the study (within approximately 5 years) | 
| Overall survival (OS) | Period from the first day of DS-3201b dose to death. | Through the end of the study (within approximately 5 years) |