A Phase 1 interventional study of DS5361b and Pembrolizumab in Advanced Solid Tumor, sponsored by Daiichi Sankyo. Recruiting at 7 sites in 2 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-02.
Sponsored by Daiichi Sankyo · Phase 1, Interventional, and Treatment
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This study aims to assess the safety, tolerability, and preliminary efficacy and to determine the MTD of DS5361b in monotherapy and combination with pembrolizumab in participants with advanced or metastatic solid tumors.
Daiichi Sankyo is the lead sponsor of 322 studies on the registry; 37 are open to participants now.
Of its 51 completed or terminated interventional studies of FDA-regulated products, 38 (75%) have results posted.
Counted across the registry records on this site, refreshed daily.
Key Inclusion Criteria:
The clinical site will screen for the full inclusion criteria per protocol.
For HNSCC participants only: have documented results from local testing of HPV for oropharyngeal cancer. If HPV status has previously been tested using this procedure, no retesting is required.
Dose Expansion (Part 3) Only:
Has histologically or cytologically confirmed, Stage IV NSCLC without actionable gene alteration.
Has histologically or cytologically confirmed recurrent or metastatic HNSCC that is considered incurable by local therapies.
Key Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.
“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.
PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.
Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.
Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Histologically or cytologically confirmed
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Relapsed and refractory
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Measurable disease
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
RECIST
The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.
“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
PD-1, PD-L1 and checkpoint inhibitors
PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.
PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Leptomeningeal disease
Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.
Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
TIA (transient ischaemic attack)
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Allogeneic and autologous transplant
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Autoimmune disease
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive DS5361b at escalating doses.
Drug: DS5361b
Participants will receive DS5361b at escalating doses in combination with Pembrolizumab.
Drug: DS5361b · Drug: Pembrolizumab
Participants will receive DS5361b in combination with Pembrolizumab at the recommended dose for expansion (RDE).
Drug: DS5361b · Drug: Pembrolizumab
Dose Escalation Part: DS5361b will be administered at escalating doses to determine the RDE. Dose Expansion Part: DS5361b will be administered at RDE.
Dose Escalation Part: Pembrolizumab will be administered at a standard dose. Dose Expansion Part: Pembrolizumab will be administered at a standard dose.
Also known as: Keytruda®
Part 1 and 2: Number of participants with Dose-Limiting Toxicities (DLTs)
A DLT is defined as any Treatment Emergent Adverse Event (TEAE) not attributable to disease or disease-related processes, environmental factors, unrelated trauma, etc, that occurs during the DLT evaluation period (Day 1 to the end of Cycle 1) and is Grade ≥3.
Time frame: Cycle 1: Day 1 up to Day 21 (each cycle is 21 days)
Part 1, 2, and 3: Number of Participants Experiencing a Treatment Emergent Adverse Event (TEAE)
TEAEs are defined as those Adverse Events (AEs) with start or worsening date during the on-treatment period (from the first dose date of trial intervention to 30 days after the last dose date of trial intervention).
Time frame: From Screening up to approximately 5 years
Part 3 Only: Objective Response Rate (ORR) Following the Administration of DS5361b at RDE(s) in Combination with Pembrolizumab
ORR is defined as the proportion of participants with a best overall response (BOR) of confirmed complete response (CR) or confirmed partial response (PR), as assessed by investigator per RECIST v1.1.
Time frame: From first dose up to approximately 5 years
Maximum Plasma Concentration (Cmax) of DS5361b
Time frame: Cycle 1: Day 1, Day 15 (each cycle is 21 days)
Time to Reach Maximum Plasma Concentration (Tmax) of DS5361b
Time frame: Cycle 1: Day 1, Day 15 (each cycle is 21 days)
Area Under the Plasma Concentration-time Curve up to the Last Quantifiable Time (AUClast) of DS5361b
Time frame: Cycle 1: Day 1 (each cycle is 21 days)
Trough Plasma Concentration (Ctrough) of DS5361b
Time frame: Cycle 1: Day 15 (each cycle is 21 days)
Part 1 and 2: Objective Response Rate (ORR) Following the Administration of DS5361b Alone and in Combination with Pembrolizumab
ORR is defined as the proportion of participants with a BOR of confirmed CR or PR, as assessed by investigator per RECIST v1.1.
Time frame: From first dose up to approximately 5 years
Disease Control Rate (DCR) Following Administration of DS5361b Alone and in Combination with Pembrolizumab
DCR is defined as the proportion of participants who achieved a BOR of confirmed CR, confirmed PR, or stable disease as assessed by investigator per RECIST v1.1.
Time frame: From first dose up to approximately 5 years
Duration of Response (DoR) Following Administration of DS5361b Alone and in Combination with Pembrolizumab
DoR is defined as the time (in months) from date of initial response (CR or PR) to the earlier date of the first objective documentation of radiographic disease progression or death due to any cause.
Time frame: From first dose up to approximately 5 years
Plan to share: Yes — 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/
Supporting information: Study protocol, Statistical analysis plan, Informed consent form
Time frame: Completed studies that has 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.
Access criteria: 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.
Data sharing details ↗ · vivli.org
No publications or documents are linked to this record.
Started Oct 2025 (actual). Primary completion is estimated for Mar 2030, 53 months after the start.
How these figures are worked out, and which studies are left out of them.
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