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Study of ATX-898 alone and in drug combination for patients with advanced solid tumors

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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study focuses on people with advanced solid tumors. It tests a new oral drug called ATX-898. The drug may be given alone (monotherapy, which means using only one medication) or together with other approved medicines such as fulvestrant, abemaciclib, and ribociclib.

The purpose is to find out how safe the new drug is and whether it shows signs of working against the cancer. Participants will first receive low doses of ATX-898 to see how it is tolerated, and the dose may be increased until side effects limit further increase (dose‑limiting toxicities). In later parts of the study, the drug will be combined with the other medicines at doses that appear safe. Throughout the study participants will have regular check‑ups, blood tests, and simple heart rhythm recordings (ECG) to monitor safety, and doctors will look for any shrinkage of tumors using standard imaging.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

Step 1
Initial enrollment and baseline assessments
After joining the study, you will undergo a series of baseline examinations that include medical history review, physical examination, laboratory tests, electrocardiogram (ecg), vital sign measurements, and imaging studies to document the extent of the advanced solid tumor.
Step 2
Part 1a – dose‑escalation monotherapy with <b>atx-898</b>
You will start taking oral atx-898 tablets. the specific dose and frequency are defined by the study protocol and will be adjusted upward in successive patient groups to find the highest dose that can be given safely.
Each treatment cycle will be followed by close monitoring for dose‑limiting toxicities (serious side effects that stop dose escalation), regular laboratory tests, ecg checks, vital sign measurements, and performance‑status assessment.
Step 3
Determination of maximum tested dose and recommended dose for expansion
Once the safety data identify the maximum tested dose (mtd) or the recommended dose for expansion (rde), you may continue receiving atx-898 at that dose for the next study phase.
Step 4
Part 1b – expansion cohort with <b>atx-898</b> monotherapy
You will remain on the established rde of oral atx-898. regular visits will be scheduled to evaluate tumor response using standard imaging criteria, as well as to continue safety monitoring.
Step 5
Part 2a – combination therapy initiation
You will start a combination regimen that includes oral atx-898 together with an intramuscular injection of fulvestrant and either oral abemaciclib (part 2a1) or oral ribociclib (part 2a2). the exact doses and dosing schedule are specified in the study protocol.
The combination will be given for a defined number of treatment cycles while safety is closely observed through laboratory tests, ecg, vital signs, and performance‑status assessments.
Step 6
Part 2b – continued combination therapy and antitumor activity assessment
You will continue the same combination of atx-898, fulvestrant, and either abemaciclib or ribociclib for additional cycles. imaging studies will be performed periodically to determine whether the tumor shows a complete or partial response.
Ongoing safety evaluations will remain in place throughout this phase.
Step 7
Continuous safety monitoring throughout the trial
Throughout all parts of the study, you will be monitored for treatment‑emergent adverse events, serious adverse events, and any laboratory abnormalities of grade 3 or higher. these assessments follow the common terminology criteria for adverse events (ctcae) version 6.0.
Step 8
Study completion and final follow‑up
At the end of the treatment period, final assessments will be performed to document overall safety, tumor response, and any long‑term effects. you may be asked to attend follow‑up visits after the study ends to collect additional safety information.

Who can join the trial?

21 criteria

Be at least 18 years old when you sign the consent form.
Have a doctor‑confirmed diagnosis of an advanced solid tumor that has spread (metastatic) or cannot be removed by surgery (unresectable).
Have enough healthy organ function (blood, liver, kidney, etc.) as defined by the study tests.
Have an ECOG performance status of 0 or 1, meaning you are fully active or able to do light work.
Be able to read and understand the study information and sign the written consent form.
For the first part of the study, have already received one or more standard cancer medicines and not have any other suitable standard options available.
If you have a solid tumor that is not breast cancer, you must have the specific biomarker that the study requires; if you have HR+/HER2‑ breast cancer, you must meet the study’s hormone‑receptor and HER2 testing criteria.
If you have HR+/HER2‑ breast cancer, you must have already received prior systemic therapy (either after surgery or for metastatic disease).
Agree to have a tumor sample taken before treatment (a biopsy) or have existing tumor tissue from the past five years that can be used.
Have at least one tumor that can be measured on scans according to the study’s RECIST 1.1 rules (the standard way doctors track tumor size).
If you are a woman who can become pregnant, you must use two forms of birth control: one highly effective method (like an IUD or hormonal pill) and one barrier method (such as a condom with spermicide) from the start of the study until at least 6 months after your last dose of ATX‑898 (or up to 2 years after fulvestrant if you are in a combination arm).
If you are a woman who cannot become pregnant (for example, after menopause or having had a hysterectomy), you do not need to use birth control.
If you are a woman of childbearing potential, you must have a negative pregnancy test (blood test for β‑human chorionic gonadotropin) before you start.
Women must agree not to breast‑feed during the study and for at least 6 months after the last dose of ATX‑898 (or up to 2 years after fulvestrant in a combination arm).
Women must agree not to donate eggs for assisted reproduction during the study and for at least 6 months after the last dose of ATX‑898 (or up to 2 years after fulvestrant).
If you are a man who has had a vasectomy, you and your partner must use a condom with spermicide from screening until at least 90 days after your last dose of ATX‑898 (or up to 2 years after fulvestrant in a combination arm).
If you are a man who has NOT had a vasectomy, you must use two forms of birth control (one must be a condom with spermicide) and you must not donate sperm from the start of the study until at least 90 days after your last dose of ATX‑898 (or up to 2 years after fulvestrant).
If a man’s partner is pregnant, he must use a condom at all times to avoid any possible exposure to the baby.
All participants must agree to follow the study schedule, attend visits, and take the medication as instructed.
For the parts of the study that involve combination therapy, you must have already received systemic treatment for stage III (locally advanced) or stage IV (metastatic) disease.
Specific cohorts (such as backfill groups, B2, B3) require that you have received prior systemic therapy and have at least one measurable lesion as defined by RECIST 1.1.

Who cannot join the trial?

19 criteria

Has had an organ transplant in the past.
Has an allergy or strong reaction to ATX-898, any other study medicines, their inactive ingredients, or (for the ribociclib group only) peanuts.
Needs strong, whole‑body steroids (called systemic corticosteroids) or other medicines that suppress the immune system within two weeks before starting the study; inhaled, nasal, joint‑injection, or skin‑applied steroids are allowed, as are short‑term steroids for temporary problems such as asthma attacks.
Has uncontrolled HIV infection or AIDS, unless the HIV is well‑controlled (viral load is undetectable and CD4 cells are ≥ 350) or, for AIDS, no serious infections have occurred in the past year and a medical monitor approves.
Tests positive for hepatitis B or hepatitis C, or has active or chronic liver disease, including severe liver scarring (called Child‑Pugh Class C cirrhosis). Treated hepatitis B or C is allowed only if a follow‑up test shows no active virus.
Has an uncontrolled illness such as an ongoing infection, heart failure with symptoms, unstable chest pain (called unstable angina), irregular heart rhythm, or a psychiatric or social problem that would make it hard to follow study rules. A heart attack, unstable angina, or acute heart syndrome within the last six months also excludes participation.
Has any condition that the doctor believes would make the study unsafe or would interfere with study measurements, such as lung scarring (interstitial lung disease), severe shortness of breath at rest or needing oxygen, serious kidney problems, major stomach or small‑bowel surgery, Crohn’s disease, ulcerative colitis, or chronic diarrhea that is moderate or worse.
For the abemaciclib groups only: has ever fainted because of a heart problem, has had dangerous fast heart rhythms from the ventricles (like ventricular tachycardia or fibrillation), or has had a sudden cardiac arrest.
For the ribociclib groups only: has a past history of lung inflammation called pneumonitis or other interstitial lung disease.
Has already received a treatment that targets the specific molecule or pathway the study drug is designed to affect.
Has any of the specific genetic changes (mutations or loss of gene copies) listed in the study protocol.
For the ribocicline groups only: is currently taking medicines, herbal products, or certain fruits/juices (such as grapefruit) that cannot be stopped seven days before the first dose because they can lengthen the heart’s QT interval (risking a dangerous rhythm called Torsades de Pointes) or strongly affect a liver enzyme called CYP3A4/5 that processes many drugs.
Cannot swallow tablets or has a condition that prevents proper absorption of medicines, such as severe stomach or intestinal disease, removal of part of the stomach or small intestine, active inflammatory bowel disease, ulcerative colitis, or a bowel blockage.
Has had another solid tumor or blood cancer that is different from the cancers being studied within the past two years, except for very early or fully cured cancers like cervical carcinoma in situ, non‑invasive bladder tumors, or non‑melanoma skin cancer.
Has brain or spinal cord (central nervous system) cancer that is causing symptoms, or has such cancer that requires steroid medication within 28 days before the first dose. Treated brain metastases are allowed if they are stable, not growing, and do not need steroids.
Has taken any chemotherapy, targeted cancer drug, or experimental cancer treatment too recently: at least 14 days (or five drug half‑lives, up to 28 days) before starting ATX‑898 alone; 21 days before starting the ATX‑898 + fulvestrant + abemaciclib combo; or 14 days (or five half‑lives, up to 28 days) before the ATX‑898 + fulvestrant + ribociclib combo.
Has had radiation therapy within 14 days before starting the study (radiation for pain relief can be given at any time).
Still has side effects from previous cancer treatments that have not returned to normal or are worse than mild (grade 1) on the standard toxicity scale, except for hair loss of any degree or mild nerve problems (grade 2 peripheral neuropathy).
Has had major surgery that required general anesthesia within 21 days before starting the study, has not fully recovered from such surgery, or plans to have major surgery while in the study. Surgery done with only local anesthesia is allowed.

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Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Centre Leon Berard
Verified
Lyon, France
Fondazione I.R.C.C.S. Istituto Neurologico Besta
Verified
Milan, Italy
Istituto Europeo Di Oncologia S.r.l.
Responsive
Milan, Italy

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Investigated drugs

ATX-898
is an experimental oral tablet being studied for the first time in people with advanced solid tumors. In this trial it is given alone to see how safe it is and how well it works, and later it is combined with other cancer medicines to test whether the combination improves tumor control.
Ribociclib
(brand name Kisqali) is an oral drug that blocks specific proteins (CDK4/6) that help cancer cells grow and divide. In this study it is used together with ATX-898 and fulvestrant to see if the two drugs can work better together against the tumor.
Fulvestrant
is an injectable hormone therapy that blocks estrogen receptors on cancer cells, stopping estrogen from helping the tumor grow. In the trial it is given with ATX-898 and either ribociclib or abemaciclib to evaluate the combined anti‑cancer effect.
Abemaciclib
(brand name Verzenios) is an oral medication that also blocks CDK4/6 proteins, preventing cancer cells from multiplying. In this study it is paired with ATX-898 and fulvestrant to test whether the three‑drug combination can more effectively shrink or control tumors.

What is already known about the treatment

Ribociclib
It is taken as a film‑coated tablet by mouth. Ribociclib is an approved medicine and is listed in many clinical guidelines for breast cancer. It is mainly used to treat hormone‑receptor‑positive, HER2‑negative advanced breast cancer. The drug works by blocking proteins called CDK4 and CDK6, which stops cancer cells from dividing, and it belongs to the class of CDK4/6 inhibitors, a type of targeted therapy.
ATX-898
ATX‑898 is given as an oral tablet that patients swallow. It is still experimental and has not received regulatory approval, being studied in early‑phase trials. The study is looking at its use for various advanced solid tumors. Early data suggest it may act on a specific cellular pathway to block tumor growth, and it is being classified as an investigational anticancer agent.
Fulvestrant
Fulvestrant is supplied as a liquid that is injected into a muscle. It is an approved drug for treating advanced hormone‑receptor‑positive breast cancer. The medication works by attaching to estrogen receptors and causing them to break down, which stops the cancer cells from receiving growth signals. It belongs to the class of estrogen receptor antagonists, a type of hormonal therapy.
Abemaciclib
Abemaciclib comes as a film‑coated tablet taken by mouth. It is an approved therapy for certain types of breast cancer and is listed in treatment guidelines. The drug is used for hormone‑receptor‑positive, HER2‑negative advanced or metastatic breast cancer. Like ribociclib, it blocks CDK4 and CDK6 to prevent cancer cells from multiplying, and it is classified as a CDK4/6 inhibitor.

Investigated diseases

Advanced solid tumors - These are malignant growths that develop in organs or tissues such as the lung, liver, colon, or breast. They begin as a localized mass of abnormal cells that multiply uncontrollably. As they enlarge, they can invade surrounding structures and disrupt normal function. Over time, cancer cells may detach and travel through the bloodstream or lymphatic system to form new growths in distant parts of the body. This process of spreading is called metastasis, which changes the disease from a localized to a systemic condition.