This clinical trial is designed to assess the safety, preliminary efficacy, and pharmacokinetics (PK) of DS3790a monotherapy and combination regimens in participants with hematological malignancies.

DS3790a may be effective in the treatment of patients with hematological malignancies. The primary objective of this study will assess the safety and preliminary efficacy of DS3790a monotherapy and combination regimens.

To be eligible to participate in this trial, an individual must meet all the following criteria:

1. Sign and date the ICF, prior to the start of any trial-specific procedures.
2. Adults >=18 years at the time the ICF is signed.
3. History of one of the histologically documented hematologic malignancies according to the 5th edition of WHO classification as specified in the protocol.
4. NHL participants only: Agree to provide baseline tumor tissue samples as specified in the protocol.
5. ECOG PS of 0, 1 or 2 assessed no more than 14 days prior to initiation of trial intervention.
6. Has adequate organ and bone marrow function as assessed by local laboratory within 14 days prior to initiation of trial intervention as specified in the protocol.
7. Has an LVEF >=50% by either an ECHO or MUGA within 28 days before the trial starts.
8. Life expectancy of at least 3 months.
9. Is willing and able to comply with scheduled visits, drug administration plan, laboratory tests, other trial procedures, and trial restrictions.
10. A woman of childbearing potential is eligible to participate if she meets all criteria as specified in the protocol.
11. A male participant capable of producing sperm is eligible to participate if he agrees to all criteria as specified in the protocol.

An individual who meets any of the following criteria will be excluded from participating in this trial:

1. Prior Allo-SCT.
2. Prior solid organ transplantation.
3. Inadequate washout period before initiation of trial intervention as specified in the protocol.
4. Evidence of brain or leptomeningeal disease (spinal cord or CNS metastases) based on history and physical examination, unless treated and with radiologically documented lack of progression within 4 weeks prior to initiation of trial intervention.
5. Uncontrolled or significant cardiovascular disease as specified in the protocol.
6. Any of the following within the past 6 months prior to enrollment: cerebrovascular accident, transient ischemic attack, or other arterial thromboembolic event.
7. Has a history of (noninfectious) ILD/pneumonitis that required corticosteroids, has current ILD/pneumonitis, or where suspected ILD/pneumonitis cannot be ruled out by imaging at screening.
8. Clinically severe pulmonary compromise resulting from intercurrent pulmonary illnesses including, but not limited to, any underlying pulmonary disorder and any autoimmune, connective tissue, or inflammatory disorder with potential pulmonary involvement, or prior pneumonectomy.
9. Has been diagnosed with another malignancy within the previous 3 years.
10. Unresolved toxicities from previous anticancer therapy, defined as toxicities (other than alopecia and lymphocytopenia) not yet resolved to NCI-CTCAE Version 5.0, Grade <=1 or baseline.
11. Evidence of ongoing uncontrolled systemic bacterial, fungal, or viral infection.
12. Has active or uncontrolled HBV, HCV, or HIV infections.

De-identified individual participant data (IPD) on completed studies 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/

Completed studies that have reached a global end or completion with all data set collected and analyzed, and 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 on completed 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.