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NCT Number: NCT07581184

A Study of [225Ac]Ac-AKY-2519 in Patients With Metastatic Castration-Resistant Prostate Cancer

This is a Phase 1b, multi-center, open-label study to evaluate the safety, tolerability, dosimetry, and pharmacokinetics (PK) of [64Cu]Cu-AKY-2519 and/or [225Ac]Ac-AKY-2519, as well as the preliminary anti-tumor activity of [225Ac]Ac-AKY-2519 in participants with metastatic castration-resistant prostate cancer (mCRPC) with and without prior exposure to 177Lu-PSMA-617 (PLUVICTO™).

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Key information

Conditions

Castration Resistant Metastatic Prostate Cancer B7H3 Genital Diseases Genital Diseases, Male Genital Neoplasms, Male MCRPC Male Urogenital Diseases Neoplasms Neoplasms by Site Prostate Cancer Prostatic Diseases Prostatic Neoplasms Urogenital Diseases Urogenital Neoplasms mCRPC (Metastatic Castration-resistant Prostate Cancer)

Age range

18 year and older

Sex eligibility

Male

Study type

Interventional

Phase

Phase 1

Primary location

Hoag Memorial Hospital Presbyterian, Irvine, California, United States

Loading trial locations.

About this study

This Phase 1b study consists of a dose escalation portion and a backfill portion. The dose escalation portion will investigate ascending doses of [225Ac]Ac-AKY-2519 across two cohorts enrolling in parallel:

  • Cohort A: participants with metastatic castration-resistant prostate cancer (mCRPC) with NO prior exposure to 177Lu-PSMA-617 (PLUVICTO™) and
  • Cohort B: participants with metastatic castration-resistant prostate cancer (mCRPC) with prior exposure to 177Lu-PSMA-617 (PLUVICTO™)

The backfill portion may enrich in two select dose levels from each cohort (Cohort A: mCRPC 177Lu-PSMA-617 (PLUVICTO™)-naïve; Cohort B: mCRPC 177Lu-PSMA-617 (PLUVICTO™)-experienced) to gather further information on the safety and efficacy and to determine the recommended phase 2 dose (RP2D) for each cohort.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age ≥ 18 years
  • Histologic or cytologic confirmation of prostatic adenocarcinoma
  • ECOG Performance Status of 0 or 1
  • Adequate end-organ function
  • Ability to give informed consent and comply with study requirements
  • Patients with CNS metastases are eligible if they have received therapy and are neurologically stable, asymptomatic and not receiving corticosteroids
  • Castrate levels of serum testosterone (< 50 ng/dL)
  • Documented disease progression on most recent prior line of therapy, either by PSA or imaging-based progression
  • Cohort B: Received 2 or more prior doses of 177Lu-PSMA-617 (PLUVICTO)

Exclusion criteria

  • Prior treatment with more than 2 Androgen receptor pathway inhibitors (ARPIs) and/or more than 1 taxane-based therapy in the mCRPC setting
  • Prior treatment with a targeted radiotherapy

o Exception: Cohort B is required to have had at least 2 prior doses of 177Lu-PSMA-617 (PLUVICTO)

  • Prior treatment with a B7-H3 targeted therapy
  • Received an investigational agent within the previous 28 days
  • Impaired cardiac function or clinically significant cardiac disease
  • Concurrent serious medical condition that would impair study participation or impact the assessment of treatment related toxicity

Treatment and study plan

[225Ac]Ac-AKY-2519 (therapeutic)

Drug

[225Ac]Ac-AKY-2519 Injection

[64Cu]Cu-AKY-2519 (imaging)

Drug

[64Cu]Cu-AKY-2519 Injection

Primary outcomes

  1. Occurrence of adverse events by severity and occurrence of serious adverse events (SAEs) in participants who received [225Ac]Ac-AKY-2519

    Time frame: Up to 30 days following last administration of [225Ac]Ac-AKY-2519

    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 and the number of patients experiencing an SAE will be reported. Up to 30 days following last administration of [225Ac]Ac-AKY-2519

  2. Occurrence of dose-limiting toxicity (DLT) in mCRPC participants with and without prior 177Lu-PSMA-617 exposure

    Time frame: From first administration of [225Ac]Ac-AKY-2519 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 will be reported separately for each cohort and by dose level within each cohort.

Secondary outcomes

  1. Occurrence of adverse events by severity and occurrence of serious adverse events (SAEs) in participants who received [64Cu]Cu-AKY-2519

    Time frame: Up to 30 days following last administration of [64Cu]Cu-AKY-2519

    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 will be reported.

  2. Objective Response Rate (ORR)

    Time frame: Up to 30 days following last administration of [225Ac]Ac-AKY-2519

    ORR 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 PCWG3-modified RECIST v1.1.

  3. Duration of Response (DoR)

    Time frame: Up to 5 years after first administration

    Duration of Response (DoR) is 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.

  4. Progression-Free Survival (PFS)

    Time frame: 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.

  5. Prostate Specific Antigen (PSA) >= 50% Response Rate (PSA50)

    Time frame: Up to 30 days following last administration of [225Ac]Ac-AKY-2519

    Will assess PSA decline of >= 50% from baseline (PSA50), using the Prostate Cancer Working Group 3 (PCWG3) criteria.

  6. Prostate Specific Antigen (PSA) >= 90% Response Rate (PSA90)

    Time frame: Up to 30 days following last administration of [225Ac]Ac-AKY-2519

    Will assess PSA decline of >= 90% from baseline (PSA90), using the Prostate Cancer Working Group 3 (PCWG3) criteria.

Study contacts

Contact information is provided by the study sponsor or research team.

Tiffany Wang, MD

CONTACT

[email protected]

+1-857-216-8482

Sponsors and collaborators

Lead sponsor

Aktis Oncology, Inc.

Industry

Registry information

Official study title

BActinium-1: A Phase 1b, Multicenter, Open-label Study to Evaluate the Safety and Efficacy of Intravenous Administration of B7-H3 Radiopharmaceutical ([225Ac]Ac-AKY-2519) in Metastatic Castration-Resistant Prostate Cancer

Acronym: BActinium-1

Important dates

Study start
2026
Primary completion
2027
Study completion
2032
First posted
May 12, 2026
Registry last updated
Jul 14, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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