Study of ASP7517 Alone and With Pembrolizumab in Participants With Advanced Solid Tumors Expressing WT1 Antigen

An AE was defined as any untoward medical occurrence in a participant, temporally associated with the use of a medicinal product, whether or not considered related to the study drug. An AE could therefore be any unfavorable & unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a medicinal product. An AE was considered "serious" if, it resulted in any of the following outcomes: resulted in death; was life-threatening; resulted in persistent or significant disability/incapacity or substantial disruption of the ability to conduct normal life functions; resulted in congenital anomaly, or birth defect; required inpatient hospitalization; or led to prolongation of hospitalization; other medically important events. A treatment-emergent adverse event (TEAE) was defined as an AE observed after the date of first dose until 30 days after the last dose.

An AE was defined as any untoward medical occurrence in a participant, temporally associated with the use of a medicinal product, whether or not considered related to the study drug. An AE could therefore be any unfavorable & unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a medicinal product. An AE was considered "serious" if, it resulted in any of the following outcomes: resulted in death; was life-threatening; resulted in persistent or significant disability/incapacity or substantial disruption of the ability to conduct normal life functions; resulted in congenital anomaly, or birth defect; required inpatient hospitalization; or led to prolongation of hospitalization; other medically important events. A treatment-emergent adverse event (TEAE) was defined as an AE observed after the date of first dose until 30 days after the last dose.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead. EOT visit was conducted for all participants after 7 days of last dose.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead. EOT visit was conducted for all participants after 7 days of last dose.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

The ECOG Scale was used to assess performance status. Grade Description: 0 - Fully active, able to carry on all pre disease performance without restriction. 1 - Restricted in physically strenuous activity, but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work. 2 - Ambulatory and capable of all self-care, but unable to carry out any work activities. Up and about more than 50% of waking hours. 3 - Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. 4 - Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 5 -Dead.

DLT: any event occurring within 28 days of first dose on C1D1 and graded as: *Non-hematologic AEs >= grade 3 and not resolving to <= grade 2 within 72 hours. *Confirmed Hy's law case. *Infusion-related reactions requiring infusion discontinuation, prolonged delay (> 2 weeks) in initiating C2 due to treatment-related toxicity. *Any treatment-related toxicity causing discontinuation in C1. *Grade >= 3 thrombocytopenia/bleeding requiring transfusion/hospitalization, grade >= 3 anemia requiring transfusion, grade 3 febrile neutropenia with/without infection and grade 5 treatment-related toxicity, grade >= 2 pneumonitis, grade >= 2 encephalopathy, meningitis or motor/sensory neuropathy. *Aspartate aminotransferase (AST) / alanine aminotransferase (ALT) > 5 × upper limit of normal (ULN) in participants without liver metastases, AST/ALT > 8×ULN in participants with liver metastases, total bilirubin > 3×ULN (grade >= 3). *Guillain-Barré syndrome/myasthenic syndrome/myasthenia gravis.

iORR was defined as the percentage of participants for each dose level whose best overall response was rated as confirmed iCR or iPR per iRECIST by independent central review. iCR was complete response based on iRECIST and defined as disappearance of all target and non-target lesions and any pathological lymph nodes must be <10 millimeter (mm) in the short axis. iPR was partial response based on iRECIST was defined as at least a 30% decrease in the sum of the diameters of target lesions, taking as a reference, the baseline sum of the diameters.

iORR assessments included:

• iORR with confirmed response by investigator assessment
• iORR with unconfirmed response by investigator assessment For confirmed response for iCR/iPR, scan had to be done 4 weeks after iPR/iCR was first observed. Participants who had iCR/iPR were considered as having confirmed response and those that did not fulfil this criteria were considered as having unconfirmed response.

ORR was defined as the percentage of participants for each dose level whose best overall response is rated as complete response (CR) or partial response (PR) per RECIST v1.1. CR was complete response based on RECIST and defined as disappearance of all target and non-target lesions and any pathological lymph nodes must be <10 mm in the short axis. PR was partial response based on RECIST and defined as at least a 30% decrease in the sum of the diameters of target lesions, taking as a reference, the baseline sum of the diameters.

ORR assessment included:

• ORR with confirmed response by investigator assessment
• ORR with unconfirmed response by investigator assessment For confirmed response for CR/PR, scan had to be done 4 weeks after PR/CR was first observed. Participants who had CR/PR were considered as having confirmed response and those that did not fulfil this criteria were considered as having unconfirmed response.

iDCR: Percentage of participants for each dose level whose best overall response is rated as confirmed iCR, iPR or iSD per iRECIST. iCR: Complete response based on iRECIST, defined as disappearance of all target/non target lesions and pathological lymph nodes must be <10 millimeter (mm) in the short axis. iPR: Partial response based on iRECIST, defined as at least 30% decrease in the sum of diameters of target lesions, with reference to the baseline sum of diameters. SD: Neither sufficient shrinkage to qualify for iPR nor sufficient increase to qualify for PD. PD: Defined as at least 20% increase in the sum of diameters of target lesions, with reference to the smallest sum of diameters recorded since the treatment started. For confirmed response for iCR/iPR, scan had to be done 4 weeks after iPR/iCR was first observed. Participants who had iCR/iPR were considered as having confirmed response and those that did not fulfil this criteria were considered as having unconfirmed response.

DCR: Percentage of participants for each dose level whose best overall response is rated as confirmed CR, PR or SD per RECIST v1.1. CR: Complete response based on RECIST and defined as disappearance of all target/non target lesions and any pathological lymph nodes must be <10 mm in the short axis. PR: Partial response based on RECIST and defined as at least a 30% decrease in the sum of diameters of target lesions, with reference to, the baseline sum of diameters. SD: Neither sufficient shrinkage to qualify for iPR nor sufficient increase to qualify for PD. PD: At least a 20% increase in the sum of diameters of target lesions, with reference to, the smallest sum of diameters recorded since treatment started. For confirmed response for CR/PR, scan had to be done 4 weeks after PR/CR was first observed. Participants who had CR/PR were considered as having confirmed response and those that did not fulfil this criteria were considered as having unconfirmed response.

iPFS was defined as the time from the start of the study treatment until death from any cause or radiographic disease progression assessed per iRECIST by independent central review and investigator assessment, whichever occurs first. Progressive Disease was defined as at least a 20% increase in the sum of the diameters of target lesions, taking as a reference, the smallest sum of diameters recorded since the treatment started. Kaplan Meier estimate was used for analysis of time-to-event endpoints.

PFS was defined as the time from the start of the study treatment until death from any cause or radiographic disease progression assessed per RECIST by independent central review and investigator assessment, whichever occurred first. Progressive Disease was defined as at least a 20% increase in the sum of the diameters of target lesions, taking as a reference, the smallest sum of diameters recorded since the treatment started. Kaplan Meier estimate was used for analysis of time-to-event endpoints.

OS was defined as the time from the date of first dose until the date of death from any cause (death date - first dose date + 1). For a participant who is not known to have died by the end of study follow-up, OS is censored at the date of last contact (date of last contact - first dose date + 1). Kaplan Meier estimate was used for analysis of time-to-event endpoints.

iDOR was defined as the time from the date of the first response iCR/iPR (whichever was first recorded) to the date of radiographical progression or date of censoring. iCR was complete response based on iRECIST and defined as disappearance of all target and non target lesions and any pathological lymph nodes must be <10 millimeter (mm) in the short axis. iPR was partial response based on iRECIST was defined as at least a 30% decrease in the sum of the diameters of target lesions, taking as a reference, the baseline sum of the diameters. Progressive Disease was defined as at least a 20% increase in the sum of the diameters of target lesions, taking as a reference, the smallest sum of diameters recorded since the treatment started.

DOR is defined as the time from the date of the first response CR/PR (whichever is first recorded) to the date of radiographical progression or date of censoring. DOR will be calculated only for the subgroup of participants with confirmed response CR/PR per RECIST v1.1, separately for independent central review and for investigator assessment. CR was complete response based on RECIST and defined as disappearance of all target and non target lesions and any pathological lymph nodes must be <10 mm in the short axis. PR was partial response based on RECIST and defined as at least a 30% decrease in the sum of the diameters of target lesions, taking as a reference, the baseline sum of the diameters. Progressive Disease was defined as at least a 20% increase in the sum of the diameters of target lesions, taking as a reference, the smallest sum of diameters recorded since the treatment started.