Study of AZD4956 as Monotherapy and in Combination With Anti-Cancer Agents in Participants With Advanced/Metastatic Homologous Recombination Deficient Solid Tumours (PARTHENON)

A Modular Open-label, Phase I/IIa Study to Assess the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Preliminary Efficacy of Ascending Doses of AZD4956 as Monotherapy, and in Combination With Anti-Cancer Agents in Participants With Advanced/Metastatic Homologous Recombination Repair Defective Solid Tumours

The purpose of this modular, first trial in human study is to assess the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary efficacy of ascending dose levels (DLs) of AZD4956 monotherapy and in combination with other anti-cancer agents in participants with advanced/metastatic solid tumours with homologous recombination repair (HRR) deficiencies.

Study Overview

• Status: Recruiting
• Conditions: Solid Tumours
• Intervention / Treatment: Drug: Saruparib; Drug: AZD4956

Detailed Description

The study consists of individual modules each evaluating the safety and tolerability of AZD4956 dosed as monotherapy, or with a specific combination partner. There are following 2 modules -

1. Module 1: AZD4956 monotherapy
2. Module 2: AZD4956 in combination with saruparib

Each module may further contain 2 parts-

• Part A (dose escalation/dose finding): To determine the safety, tolerability, PK, PD, and preliminary efficacy of AZD4956 as monotherapy or in combination.
• Part B (dose expansion): To further evaluate the safety and preliminary efficacy of AZD4956 in combination with other anti-cancer agents.

• Study Type: Interventional
• Enrollment (Estimated): 180
• Phase: Phase 2; Phase 1

Contacts and Locations

• Study Contact: Name: AstraZeneca Clinical Study Information Center; Phone Number: 1-877-240-9479; Email: information.center@astrazeneca.com

Study Locations

• Australia
  • Melbourne, Australia, 3000
    • Not yet recruiting
    • Research Site
  • Westmead, Australia, 2145
    • Not yet recruiting
    • Research Site
• Japan
  • Chūōku, Japan, 104-0045
    • Not yet recruiting
    • Research Site
  • Kashiwa, Japan, 277-8577
    • Not yet recruiting
    • Research Site
• South Korea
  • Seoul, South Korea, 03080
    • Not yet recruiting
    • Research Site
  • Seoul, South Korea, 120-752
    • Not yet recruiting
    • Research Site
• Spain
  • Barcelona, Spain, 08036
    • Not yet recruiting
    • Research Site
  • Barcelona, Spain, 8035
    • Not yet recruiting
    • Research Site
  • Barcelona, Spain, 08023
    • Not yet recruiting
    • Research Site
  • Logroño, Spain, 26006
    • Not yet recruiting
    • Research Site
  • Pozuelo de Alarcón, Spain, 28223
    • Not yet recruiting
    • Research Site
  • Seville, Spain, 41013
    • Not yet recruiting
    • Research Site
• United Kingdom
  • London, United Kingdom, SE1 9RT
    • Not yet recruiting
    • Research Site
  • Sutton, United Kingdom, SM25PT
    • Not yet recruiting
    • Research Site
• United States
  • New York
    • New York, New York, United States, 10065
      • Not yet recruiting
      • Research Site
  • Rhode Island
    • Providence, Rhode Island, United States, 02903
      • Not yet recruiting
      • Research Site
  • Texas
    • Houston, Texas, United States, 77030
      • Not yet recruiting
      • Research Site
  • Virginia
    • Fairfax, Virginia, United States, 22031
      • Recruiting
      • Research Site

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Core Inclusion Criteria:

• Documented locally advanced or metastatic solid tumour malignancy.
• Eastern cooperative oncology group (ECOG) performance status of 0 or 1 with no deterioration over the previous 2 weeks prior to screening and first day of dosing.
• Minimum life expectancy ≥ 12 weeks.
• Adequate organ and marrow function.
• Female participants must not breastfeed and must not donate or retrieve ova for their own use from screening to approximately 6 months after the last dose of study intervention.

Module 1 Inclusion Criteria:

• Demonstrated evidence of disease progression.
• Participants must have advanced or metastatic solid tumours.
• Participants may have received up to one prior line of therapy with a poly (adenosine diphosphate-ribose) polymerase inhibitor (PARPi)-based regimen (either as a treatment or as maintenance).

Module 2 Inclusion Criteria:

Part A (AZD4956 in Combination with Saruparib Dose Escalation) and Part A-PD (PD Backfill Cohorts):

• Participants must have one of the following conditions-

  1. Histologically or cytologically confirmed carcinoma of the breast with recurrent locally advanced or metastatic disease and evidence of a predicted loss of function germline or somatic mutation.
  2. Histologically or cytologically confirmed advanced ovarian, fallopian tube, or primary peritoneal cancer.
  3. Histologically or cytologically confirmed adenocarcinoma of the prostate and advanced/metastatic castrate resistant prostate cancer (CRPC).
  4. Histologically or cytologically confirmed advanced/metastatic pancreatic cancer.
• Participants must have evaluable disease.
• Participants in PD backfill cohorts must not have received prior therapy with a PARPi-based regimen (either as a treatment or as maintenance).

Part A (PD Backfill Cohorts) - Participants Undergoing Paired Biopsies:

- Participants must have a tumour suitable for biopsy.

Part A-Non-PD (Non-PD Backfill Cohorts) and Part B (Dose Expansion Cohorts):

• Participants must have histologically or cytologically confirmed adenocarcinoma of the prostate and advanced/metastatic CRPC.
• Participants must have documented metastatic disease by clear evidence of ≥ 1 bone lesion (defined as one lesion with positive uptake on bone scan) and/or ≥ 1 soft tissue lesion (measurable or non-measurable).
• Participants must have received the prior approved systemic therapies for metastatic prostate cancer.
• Participants must not have received prior therapy with a PARPi-based regimen (either as a treatment or as maintenance).

Core Exclusion Criteria:

• Any significant laboratory finding or any severe and uncontrolled medical condition.
• Participants with any known predisposition to bleeding.
• Spinal cord compression or symptomatic and unstable brain metastases or leptomeningeal disease.
• Allogenic organ transplantation.
• Known to have active infection, including hepatitis B virus (HBV) or hepatitis C virus (HCV).
• Known history of infection with human immunodeficiency virus (HIV).
• Active gastrointestinal disease or other condition that will interfere significantly with the swallowing, absorption, distribution, metabolism or excretion of oral therapy.
• Participants with history of myelodysplastic syndrome (MDS)/acute myeloid leukaemia (AML) or with features suggestive of MDS/AML.
• Participants with a known hypersensitivity to the investigational product(s) or any of the excipients of the product(s).
• Previous dosing with AZD4956.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

6

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Module 1 Part A: AZD4956 monotherapy (Dose escalation); Participants will receive AZD4956 as monotherapy at ascending dose levels.	Drug: AZD4956; AZD4956 will be administered orally.
Experimental: Module 2 Part A: AZD4956 + saruparib (Dose escalation); Participants will receive AZD4956 at ascending dose levels in combination with saruparib.	Drug: Saruparib; Saruparib will be administered orally.; Drug: AZD4956; AZD4956 will be administered orally.
Experimental: Module 2 Part A Optional PD backfill cohort: AZD4956 + saruparib; Participants will receive AZD4956 in combination with saruparib.	Drug: Saruparib; Saruparib will be administered orally.; Drug: AZD4956; AZD4956 will be administered orally.
Experimental: Module 2 Part A Optional PD backfill cohort: Saruparib monotherapy; Participants will receive saruparib monotherapy.	Drug: Saruparib; Saruparib will be administered orally.
Experimental: Module 2 Part A Optional non-PD backfill cohort: AZD4956 + saruparib; Participants with metastatic castrate resistant prostate cancer (mCRPC) will receive AZD4956 in combination with saruparib.	Drug: Saruparib; Saruparib will be administered orally.; Drug: AZD4956; AZD4956 will be administered orally.
Experimental: Module 2 Part B: AZD4956 + saruparib (Dose expansion); Participants will receive AZD4956 in combination with saruparib.	Drug: Saruparib; Saruparib will be administered orally.; Drug: AZD4956; AZD4956 will be administered orally.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Parts A and B: Number of participants with adverse events (AEs) and serious adverse events (SAEs)	To assess the safety and tolerability of AZD4956 monotherapy and in combination with anti-cancer agent(s).	From Screening (Day -28) to follow-up (up to 3.5 years)
Part B: Progression free survival (PFS)	PFS is defined as the time from the start of treatment until the date of objective disease progression or death (by any cause in the absence of progression), regardless of whether the participants withdraw from study treatment or receive another anti-cancer therapy prior to progression.	Up to 3.5 years
Part A - Number of participants with dose-limiting toxicities (DLTs)	To assess the safety and tolerability of AZD4956 monotherapy and in combination with anti-cancer agent(s).	Up to 28 days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Objective response (OR)	OR is defined as if a participant achieves a best overall response (BOR) of confirmed complete response (CR) or partial response (PR), as assessed by the investigator, according to response evaluation criteria in solid tumours (RECIST) v1.1 criterion.	Up to 3.5 years
Duration of response (DoR)	DoR is defined as the time from the date of first documented OR assessed by RECIST v1.1, in the absence of progression on bone scan assessed by prostate cancer working group 3 (PCWG3), until the date of documented disease progression or death in the absence of disease progression.	Up to 3.5 years
Best Overall Response (BOR)	To assess the preliminary anti-tumour activity of AZD4956 monotherapy and in combination with anti-cancer agent(s).	Up to 3.5 years
Time to response (TTR)	TTR is defined as the time from the date of first dose of study intervention until the date of first documented OR assessed by RECIST v1.1, in the absence of progression on bone scan assessed by PCWG3, which is subsequently confirmed.	Up to 3.5 years
Disease control (DC)	DC is defined as if a participant has achieved a best OR of confirmed CR or PR or SD as BOR assessed by RECIST v1.1, in the absence of progression on bone scan assessed by PCWG3.	Up to 3.5 years
Clinical benefit rate (CBR)	CBR is defined as the percentage of advanced cancer participants who achieve CR, PR, or at least 16 weeks/24 weeks of stable disease, assessed by RECIST v1.1, in the absence of progression on bone scan assessed by PCWG3, as a result of therapy.	Up to 3.5 years
Part A: Progression free survival (PFS)	PFS is defined as the time from the start of treatment until the date of objective disease progression or death (by any cause in the absence of progression), regardless of whether the participants withdraw from study treatment or receive another anti-cancer therapy prior to progression.	Up to 3.5 years
Percentage change from baseline in tumour size	The best percentage change from baseline in target lesion (TL) tumour size is the largest decrease (or smallest increase) from baseline for a participant, using RECIST v1.1 assessments.	Up to 3.5 years
Number of participants with cancer antigen 125 (CA125) response (for ovarian cancer participants)	CA125 response is defined as if at least a 50% reduction in CA125 levels from a pre-treatment sample.	From baseline up to 3.5 years
Radiological progression free survival (rPFS) (for prostate cancer participants)	PFS is defined as the time from the start of treatment until the date of objective disease progression or death (by any cause in the absence of progression), regardless of whether the participants withdraw from study treatment or receive another anti-cancer therapy prior to progression.	Up to 3.5 years
Change from baseline in prostate specific antigen 50 (PSA50) response rate (for prostate cancer participants)	PSA50 response is defined as if a ≥ 50% decrease in PSA from baseline to the lowest post-baseline PSA result, confirmed by a second consecutive PSA assessment at least 3 weeks later has been achieved.	From baseline up to 3.5 years
Change from baseline in PSA90 response rate (for prostate cancer participants)	PSA90 response is defined as if a ≥ 90% decrease in PSA from baseline to the lowest post-baseline PSA result, confirmed by a second consecutive PSA assessment at least 3 weeks later has been achieved.	From baseline up to 3.5 years
Change from baseline in PSA undetectable rate	Undetectable PSA is defined as a measurement of < 0.2 ng/mL.	At 3, 6 and 9 months
Time to PSA50/90 response (for prostate cancer participants)	Time to PSA50/90 response is defined as the time from the date of first dose of study intervention until the date of first documented PSA response (≥ 50%/90% decrease in PSA from baseline) that is confirmed by a second consecutive PSA assessment at least 3 weeks later.	Up to 3.5 years
Time to PSA progression (for prostate cancer participants)	Time to PSA progression is defined as the time from date of first dose of study intervention until the date of first documented PSA progression or the last PSA result in the absence of progression.	Up to 3.5 years
PSA PFS at 6 months (PSA-6)	PSA progression is defined as an increase in PSA of ≥ 25% from the nadir and an absolute increase of at least 2 ng/mL above nadir beyond 12 weeks. To assess the preliminary anti-tumour activity of AZD4956 monotherapy and in combination with anti-cancer. agent(s)	At 6 months
Area under the concentration-time curve (AUC)	To characterise the pharmacokinetics (PK) of AZD4956 when given orally as monotherapy and in combination with anti-cancer agent(s).	From date of first dose of study intervention up to 59 days after first dose
Maximum concentration (Cmax)	To characterise the pharmacokinetics (PK) of AZD4956 when given orally as monotherapy and in combination with anti-cancer agent(s).	From date of first dose of study intervention up to 59 days after first dose
Time to maximum concentration (Tmax)	To characterise the pharmacokinetics (PK) of AZD4956 when given orally as monotherapy and in combination with anti-cancer agent(s).	From date of first dose of study intervention up to 59 days after first dose
Individual and cumulative percentage of dose excreted unchanged in urine from time t1 to time t2 (fe(t1-t2))	To characterise the pharmacokinetics (PK) of AZD4956 when given orally as monotherapy and in combination with anti-cancer agent(s).	From date of first dose of study intervention up to 16 days after first dose
Renal clearance (CLR)	To characterise the pharmacokinetics (PK) of AZD4956 when given orally as monotherapy and in combination with anti-cancer agent(s).	From date of first dose of study intervention up to 16 days after first dose
Individual and cumulative amount of unchanged drug excreted into urine from time t1 to time t2 (Ae(t1-t2))	To characterise the pharmacokinetics (PK) of AZD4956 when given orally as monotherapy and in combination with anti-cancer agent(s).	From date of first dose of study intervention up to 16 days after first dose
Change in amount of KRAB-associated protein-1 phosphorylated on serine 824 [pKAP1 (Ser824)] biomarker in tumour cells at baseline and during treatment	To evaluate PD of AZD4956 in tumour cells when given orally as monotherapy and in combination with anti-cancer agent(s).	From Baseline up to 3.5 years

Collaborators and Investigators

• Sponsor: AstraZeneca

Study record dates

Study Major Dates

• Study Start (Actual): March 17, 2026
• Primary Completion (Estimated): March 29, 2030
• Study Completion (Estimated): March 29, 2030

Study Registration Dates

• First Submitted: February 26, 2026
• First Submitted That Met QC Criteria: February 26, 2026
• First Posted (Actual): March 3, 2026

Study Record Updates

• Last Update Posted (Actual): May 26, 2026
• Last Update Submitted That Met QC Criteria: May 22, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Pharmacokinetics; Pharmacodynamics; Advanced/metastatic homologous recombination repair defective solid tumours; Poly (adenosine diphosphate-ribose) polymerase inhibitor (PARPi)
• Other Study ID Numbers: D8570C00001; 2025-524171-22-00 (Ctis)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

IPD Plan Description

Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal Vivli.org. All requests will be evaluated as per the AZ disclosure commitment: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

Yes, indicates that AZ are accepting requests for IPD, but this does not mean all requests will be shared.

• IPD Sharing Time Frame: AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA PhRMA Data Sharing Principles. For details of our timelines, please rerefer to our disclosure commitment at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.
• IPD Sharing Access Criteria: When a request has been approved AstraZeneca will provide access to the anonymized individual patient-level data via secure research environment Vivli.org. Signed Data Usage Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No