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AZD8421

Phase 1

ER+ HER2- Advanced Breast Cancer | Small molecule | Oncology |AstraZeneca PLC|Last Updated: Aug 6, 2026

Success Probability

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Market & Valuation

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Trial Design

CONTROLLED
Total Trials1
Total Enrollment564

FDA Designations

No designations recorded

Clinical trial landscape

AZD8421 · 1 trial · 2 indications

Phase 1 1
NCT06188520A First-in-human Dose Escalation and Expansion Study to Evaluate the Safety, and Tolerability of AZD8421 Alone or in Combination in Participants With Selected Advanced or Metastatic Solid TumorsER+ HER2- Advanced Breast Cancer
RECRUITING564 Analytics
PHASE1RECRUITING
A First-in-human Dose Escalation and Expansion Study to Evaluate the Safety, and Tolerability of AZD8421 Alone or in Combination in Participants With Selected Advanced or Metastatic Solid Tumors
ER+ HER2- Advanced Breast CancerUnlock trial analytics

Study Endpoints

Primary Endpoints

Incidence of dose limiting toxicities (DLTs) as defined in the protocol.
From start of treatment until the end of DLT period, assessed up to 28 days.

Percentage of participants with incidence of DLTs.

Incidence of AEs/SAEs
From start of treatment until the end of safety follow-up, approximately 18 months.

Percentage of participants with incidence of AEs/SAEs.

Clinically significant changes from baseline in clinical laboratory parameters, vital signs and ECGs.
From start of treatment until the end of safety follow-up, approximately 18 months.

Percentage of participants with clinically significant changes from baseline in clinical laboratory parameters, vital signs and ECGs.

Discontinuation of AZD8421 due to toxicity
From start of treatment until the end of safety follow-up, approximately 18 months.

Percentage of participants that have discontinued AZD8421 due to toxicity.

Secondary Endpoints

Overall Response Rate (ORR)
8 weeks from start of treatment until end of treatment or objective disease progression, approximately 18 months.
Duration of Response (DoR)
8 weeks from start of treatment until end of treatment or objective disease progression, approximately 18 months.
Disease control rate (DCR)
24 weeks after the start of treatment.
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Study Design & Arms

AllocationNON_RANDOMIZED
MaskingNONE
ModelSEQUENTIAL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Module 1EXPERIMENTALAZD8421 monotherapy
Module 2AEXPERIMENTALAZD8421 with camizestrant and CDK4/6 inhibitor

Interventions

NameTypeDescription
AZD8421DRUGCDK2 inhibitor
CamizestrantDRUGSERD
RibociclibDRUGCDK4/6 inhibitor
PalbociclibDRUGCDK4/6 inhibitor
AbemaciclibDRUGCDK4/6 inhibitor
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Eligibility Criteria

Age Range18 Years to N/A
SexFEMALE
Healthy VolunteersNo
Study Sites14

Inclusion Criteria: * Female participants only, aged 18 or above * Participants with advanced solid tumors must have received prior adequate therapy in accordance with local practice for their tumor type and stage of disease, or, in the opinion of the Investigator, a clinical study is the best opti...

Countries:United StatesAustraliaSouth KoreaSpainUnited Kingdom
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Competitive Landscape -Breast Cancer 402 trials (matched to "ER+ HER2- Advanced Breast Cancer")

Top 20 of 92 competitors

CompanyTickerTrialsLead PhaseDrugs
AstraZeneca PLCAZN47PHASE3Fulvestrant, Capivasertib
Merck & Co., Inc.MRK12PHASE3Pembrolizumab, Paclitaxel, Doxorubicin, Epirubicin, Cyclophosphamide
Eli Lilly and CompanyLLY27PHASE3Abemaciclib, Standard Adjuvant Endocrine Therapy
BioNTech SE Sponsored ADRBNTX7PHASE3DB-1303/BNT323, T-DM1
Gilead Sciences, Inc.GILD13PHASE3Sacituzumab Govitecan-hziy, Eribulin, Capecitabine Product, Gemcitabine, Vinorelbine
Novartis AG Sponsored ADRNVS30PHASE3Ribociclib
Pfizer Inc.PFE34PHASE3ARV-471, Fulvestrant
BeOne Medicines Ltd. Sponsored ADRONC5PHASE3BGB-43395, Letrozole, Abemaciclib, Palbociclib, Ribociclib
Olema Pharmaceuticals, Inc.OLMA5PHASE3Palazestrant, Fulvestrant, Anastrozole, Letrozole, Exemestane
Jazz Pharmaceuticals Public Limited CompanyJAZZ3PHASE3Zanidatamab, Trastuzumab, Eribulin, Vinorelbine, Gemcitabine
Celcuity Inc.CELC3PHASE3Gedatolisib, Palbociclib, Fulvestrant, Alpelisib
Relay Therapeutics, Inc.RLAY2PHASE3Zovegalisib, Capivasertib, Fulvestrant
GSK plc Sponsored ADRGSK2PHASE3Niraparib
Greenwich LifeSciences, Inc.GLSI1PHASE3GLSI-100
Bristol-Myers Squibb CompanyBMY5PHASE2Iza-bren, Nab-paclitaxel, Paclitaxel, Capecitabine, Carboplatin
BriaCell Therapeutics CorpBCTX2PHASE3SV-BR-1-GM, Cyclophosphamide, Interferon infiltration of the inoculation site, Retifanlimab, Treatment of Physician's Choice
Incyte CorporationINCY4PHASE2Ruxolitinib, Capecitabine, Regorafenib
Natera, Inc.NTRA3PHASE2Discontinuation of the anti-HER2 maintenance therapy
Puma Biotechnology, Inc.PBYI3PHASE2Neratinib, Loperamide, Colesevelam
Atossa Therapeutics, Inc.ATOS1PHASE2endoxifen, goserelin
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Recent Changes (Last 90 Days)

LOWAug 6, 2026NCT06188520lastUpdatePostDate: changed
LOWAug 6, 2026NCT06188520lastUpdatePostDate: changed
LOWJun 23, 2026NCT06188520lastUpdatePostDate: changed
LOWJun 23, 2026NCT06188520lastUpdatePostDate: changed

Frequently asked questions about AZD8421

What is AZD8421 used for?

AZD8421 is an investigational small molecule being studied for the treatment of ER+ HER2- advanced breast cancer. It is also being evaluated in high-grade serous ovarian cancer (HGSOC). The drug is currently in Phase 1 clinical development and has not been approved by regulatory authorities.

Who makes AZD8421?

AZD8421 is being developed by AstraZeneca PLC, a biopharmaceutical company traded on the stock exchange under the ticker symbol AZN. The company is conducting a first-in-human study of the drug in patients with selected advanced or metastatic solid tumors.

What phase is AZD8421 in?

AZD8421 is in Phase 1 clinical development. It is currently being evaluated in a first-in-human dose escalation and expansion study, which is actively recruiting participants. The drug is investigational and has not yet been approved for any use.

What clinical trials is AZD8421 in?

AZD8421 is being studied in clinical trial NCT06188520, a first-in-human dose escalation and expansion study. This Phase 1 trial is evaluating the safety and tolerability of AZD8421 alone or in combination in participants with ER+ HER2- advanced breast cancer and high-grade serous ovarian cancer. The trial is currently recruiting.

How does AZD8421 work?

AZD8421 is a small molecule drug being developed for oncology indications. Its specific molecular target has not been disclosed in the available information. The drug is being studied for its potential to treat advanced solid tumors, including ER+ HER2- breast cancer and high-grade serous ovarian cancer.

Is AZD8421 the same as any other drug?

No alternative names for AZD8421 have been disclosed. The drug is identified solely by its code name AZD8421 in clinical trial registrations and development programs. It is a distinct investigational compound being developed by AstraZeneca.