A Study of [225Ac]Ac-AKY-1189 in Patients With Solid Tumors

Part 1: Number of Patients with Dose-Limiting Toxicities

Timeframe: From enrollment to the end of Cycle 1 (each cycle is 28 days)

• Dose-limiting toxicities (DLTs) is defined as any predefined AE occurring during the DLT observation period, except those that are clearly and incontrovertibly due to extraneous circumstances. The number of patients who experience a DLT in Part 1, will be reported by dose level.

Part 1: Occurence of Adverse Events by Severity

Timeframe: Up to the End of Treatment (30 days after the last dose)

• An AE is defined as any untoward medical occurrence in a participant administered study drug, which does not necessarily have to have a causal relationship with the study drug. The number of patients experiencing an AE in Part 1 will be reported.

Part 2: Objective Response Rate (ORR)

Timeframe: Up to 30 days following last administration

• Objective response rate is defined as the percentage of patients who achieved a best overall response of confirmed Complete Response (CR) or Partial Response (PR), as determined by the investigator based on RECIST 1.1, by tumor types.

Part 1: Objective Response Rate (ORR)

Timeframe: Up to 30 days following last adminstration

• Objective response rate is defined as the percentage of patients who achieved a best overall response of confirmed Complete Response (CR) or Partial Response (PR), as determined by the investigator based on RECIST 1.1, by dose level.

Part 2: Occurence of Adverse Events by Severity

Timeframe: Up to End of Treatment (30 days after the last dose)

• An AE is defined as any untoward medical occurrence in a participant administered study drug, which does not necessarily have to have a causal relationship with the study drug. The number of patients experiencing an AE in Part 2 will be reported.

Part 1 and 2: Duration of Response (DOR)

Timeframe: Up to 5 years after first administration

• Duration of Response (DoR) was defined as the time from the date of the first documentation of objective response (complete response \[CR\] or partial response \[PR\]) to the date of the first objective documentation of progressive disease (PD) or death due to any cause.

Part 1 and 2: Progression-Free Survival (PFS)

Timeframe: Up to 5 years after first administration

• PFS is defined as the time from treatment initiation to the first documented disease progression per RECIST 1.1 or death due to any cause, whichever occurs first.