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ASTX660

Phase 1

Advanced Cancer | Small molecule | Oncology |Merck & Company, Inc.|Last Updated: Jun 25, 2026

Success Probability

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Market & Valuation

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Trial Design

CONTROLLEDBiomarker
Total Trials1
Total Enrollment61

FDA Designations

No designations recorded

Clinical trial landscape

ASTX660 · 1 trial · 3 indications

Phase 1 1
NCT05082259ASTEROID: A Trial of ASTX660 in Combination With PembrolizumabAdvanced Cancer
ACTIVE NOT_RECRUITING61 Analytics
PHASE1ACTIVE NOT_RECRUITING
ASTEROID: A Trial of ASTX660 in Combination With Pembrolizumab
Advanced CancerUnlock trial analytics

Study Endpoints

Primary Endpoints

Determination of MTD and RP2D
12 months

To determine the Maximum Tolerated Dose (MTD) of ASTX660 in combination with Pembrolizumab based on dose-limiting toxicities (DLTs) up to 6 weeks from start of treatment and the RP2D.

Safety and tolerability
12 months

To determine the frequency, severity and causality of each adverse event to the combination of ASTX660 and Pembrolizumab according to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) Version 5.0.

Preliminary anti-tumour activity evaluation (in Part B)
24 months

Assessment of disease response by imRECIST criteria, clinical benefit rate, best changes in tumour size, progression-free survival and duration of response.

Secondary Endpoints

Preliminary anti-tumour activity evaluation (in Part A)
12 months
Pharmacokinetics of ASTX660
12 months
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Study Design & Arms

AllocationNON_RANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeHEALTH_SERVICES_RESEARCH

Treatment Arms

ArmTypeDescription
Part A-EscalationEXPERIMENTALIncreasing doses of ASTX660 in combination with a fixed dose of pembrolizumab to establish the maximum tolerated dose (MTD) of ASTX660 and Pembrolizumab when given in combination in patients with advanced solid tumours. escalating doses of ASTX660 will be investigated in combination with a fixed dose of Pembrolizumab (200mg). ASTX660 administration will follow a 7 day on / 14 day off pattern (ie dosing for 7 consecutive days leading up to administration of the immune check-point inhibitors). Therefore in Cycle 1, ASTX660 will be given alone from Day 1 to Day 7, followed by a 14 day break, then taken again in Cycle 2 . Each cycle will run for a period of 21 days, with ASTX660 taken always on Days 1 to 7 and Pembrolizumab given always on Day 8. Up to 4 dose levels of ASTX660 will be explored.
Part B-ExpansionEXPERIMENTALPatients in Part B will be treated at the RP2D as determined by the SRC after the initial dose escalation (Part A) has been completed. The treatment schedule will be the same as that for Part A, i.e. each cycle will be 21 days-long. Pembrolizumab will always be administered on D8 of every cycle. ASTX660 will be taken daily on Days 1-7. Part B will be split into 3 cohorts; Cohort B1, Cohort B2 and Cohort B3. Cohort B1: Patients with Immune-checkpoint refractory tumours Cohort B2: Patients with PD-L1 positive Cervical Cancer Cohort B3: Patients with Triple Negative Breast Cancer

Interventions

NameTypeDescription
ASTX660DRUGASTX660 will be supplied as capsules. Each hydroxylpropyl methylcellulose (HPMC) capsule contains either 30 mg or 90 mg of ASTX600 free-base equivalents, suitable for oral administration. Bottles are labelled with the capsule strength (ie, 30 mg or 90 mg) and are further distinguished by different-colored labels. Each bottle contains 14 capsules and an oxygen-absorber (not to be consumed).
PembrolizumabDRUGPembrolizumab Solution for Infusion 100 mg/vial is a liquid drug product supplied as a clear to opalescent solution, essentially free of visible particles, in Type I glass vials and manufactured using the fully formulated drug substance with L-histidine as buffering agent, polysorbate 80 as surfactant, and sucrose as stabilizer/tonicity modifier. Pembrolizumab Solution for Infusion can be further diluted with normal saline or 5% dextrose in the concentration range of 1 to 10 mg/mL in IV containers made of polyvinyl chloride (PVC) or non-PVC material.
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites3

Inclusion Criteria: 1. PART A: Patients with histologically or cytologically confirmed malignant advanced solid tumours, refractory to conventional treatment, or for which no conventional therapy exists or is declined by the patient. PART B1: Patients with histologically or cytologically confir...

Countries:United Kingdom
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Competitive Landscape -Cancer 5 trials (matched to "Advanced Cancer")

Frequently asked questions about ASTX660

What is ASTX660 used for?

ASTX660 is an investigational small molecule being studied for the treatment of advanced cancer, including cervical cancer and triple negative breast cancer. It is currently in Phase 1 clinical development and has not been approved by regulatory authorities.

Who is developing ASTX660?

ASTX660 is being developed by Merck & Company, Inc., a pharmaceutical company traded on the New York Stock Exchange under the ticker symbol MRK. The drug is currently in Phase 1 clinical trials for advanced cancer indications.

What phase is ASTX660 in?

ASTX660 is in Phase 1 clinical development. It is an investigational drug, meaning it has not yet received regulatory approval and is still being evaluated in clinical trials for safety and efficacy in patients with advanced cancer.

What clinical trials is ASTX660 in?

ASTX660 is being studied in a Phase 1 clinical trial with the identifier NCT05082259, titled "ASTEROID: A Trial of ASTX660 in Combination With Pembrolizumab." This active trial is enrolling approximately 61 participants in the United Kingdom and is not yet recruiting new patients.

Is ASTX660 being studied in combination with other drugs?

Yes, ASTX660 is being studied in combination with pembrolizumab in the ASTEROID clinical trial (NCT05082259). This Phase 1 trial is evaluating the combination in patients with advanced cancer, including cervical cancer and triple negative breast cancer.