DS-3201b is an experimental drug that is being investigated in clinical research.

Adults with non-Hodgkin lymphoma (NHL) may be able to join this study if their disease has come back after remission or is not responding to current treatment

This study has three parts. The Dose Escalation part is designed is to find the safe dose of DS-3201b that adults with advanced NHL can tolerate. The Dose Expansion phase will determine how effective DS-3201b is for rare types of NH and collect additional safety data. Last, the Drug-Drug Interaction (DDI) Cohort (US Only) will evaluate the effect of DS-3201b on the pharmacokinetics (PK) of midazolam and digoxin when co-administered to patients with NHL

Inclusion Criteria:

• Has hematocytological or pathological diagnosis of non- Hodgkin's lymphoma (NHL)

• Has relapsed from or is refractory to standard treatment or no standard treatment is available

• Is the age of majority in their country (18 in the US and 20 in Japan) at the time of informed consent

• Has Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1

• Has at least one evaluable lesion site (not applicable for the DDI cohort)

• Has preserved organ function based on baseline laboratory data at screening tests

• If of reproductive potential, agrees to avoid harvesting ova or sperm, and to use a protocol-defined form of contraception or avoid intercourse, during and upon completion of the study, and for at least 3 months after the last dose of study drug

• Tumor biopsy collections:

  1. willing to provide archived or fresh tumor tissue samples that are sufficient for comprehensive genomic and/or proteomic analyses at baseline

  2. [US only] willing to provide fresh on-treatment tumor biopsy if deemed acceptable risk by the investigator

     [Japan only] fresh on-treatment tumor biopsy should be performed if deemed acceptable risk by the investigator

  3. willing to provide optional fresh end-of-treatment biopsy

For ATL subjects:

• Has a positive test result for human T-lymphotropic virus type I antibody
• Has ATL subtype classified as acute, lymphomatous, or chronic with poor prognostic factor
• Has diagnosis of relapse (including relapse after partial remission [PR]) or treatment-resistant ATL at the time of informed consent after prior treatment with at least 1 anti-cancer medication regimen

Exclusion Criteria:

• Has been diagnosed with protocol-defined cutaneous T-cell lymphoma or T-cell leukemia. For DDI cohort, CTCL is not exclusionary.
• Has a history or presence of central nervous system (CNS) involvement
• Has a medical history, complication or other malignancy considered inappropriate for participation in the study, or a serious physical or psychiatric disease, the risk of which may be increased by participation in the study
• Has received drugs or other treatments not allowed by the protocol
• History of treatment with other enhancer of zeste (EZH) inhibitors
• Has had allogeneic hematopoietic stem cell transplantation (HTCP) within 90 days before scheduled dosing on Cycle 1 Day 1
• Is pregnant or breastfeeding
• Is otherwise deemed ineligible to participate by the investigator or sub-investigator

DDI Cohort Only:

• Has received following medications within 14 days prior to study drug administration
• Any CYP3A inhibitors/inducers including weak CYP3A inhibitors/inducers, and P-gp inhibitors, midazolam as well as digoxin

De-identified individual participant data (IPD) and applicable supporting clinical trial documents may be available upon request at https://vivli.org/. In cases where clinical trial data and supporting documents are provided pursuant to our company policies and procedures, Daiichi Sankyo will continue to protect the privacy of our clinical trial participants. Details on data sharing criteria and the procedure for requesting access can be found at this web address: https://vivli.org/ourmember/daiichi-sankyo/

Studies for which the medicine and indication have received European Union (EU) and United States (US), and/or Japan (JP) marketing approval on or after 01 January 2014 or by the US or EU or JP Health Authorities when regulatory submissions in all regions are not planned and after the primary study results have been accepted for publication.

Formal request from qualified scientific and medical researchers on IPD and clinical study documents from clinical trials supporting products submitted and licensed in the United States, the European Union and/or Japan from 01 January 2014 and beyond for the purpose of conducting legitimate research. This must be consistent with the principle of safeguarding study participants' privacy and consistent with provision of informed consent.