ClinicalTrials.gg
Active, not recruitingNCT03425838Updated May 20, 2026

Endocrine Therapy Plus CDK4/6 in First or Second Line for Hormone (SONIA) Receptor Positive Advanced Breast Cancer

A Phase 3 interventional study of CDK 4/6 inhibitor and Non-Steroidal Aromatase Inhibitor in Breast Neoplasm Female, sponsored by Borstkanker Onderzoek Groep. Active, not recruiting at 72 sites in Netherlands. Open to female participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-05-20.

Sponsored by Borstkanker Onderzoek Groep · Phase 3, Interventional, and Treatment

Phase
Phase 3
Study type
Interventional
Enrollment
1,050
Allocation
Randomized
Ages
18 Years and older
Sex
Female
01

Where this study stands

Counted across the records on this site · 2026-11-12

Among 390 studies in Breast Neoplasms with a site in Netherlands — 71 open to participants now, 117 under way, 35 of them phase 3. Breast Neoplasms · Netherlands.

Enrollment
42nd of 314
1,050 · median 189
Started
2017
with 20 others
Phase 3
105 of 390
10 open now
Primary completion
2023-03
later than 11 of 116 live
Registered
226th of 390
by date

Among the 390 studies in Breast Neoplasms with a site in Netherlands, this one is the 42nd largest by enrollment of the 314 interventional ones that give a count, is one of 21 that started in 2017, is one of 105 in phase 3, reaches primary completion later than 11 of the 116 other live ones, and was the 226th registered.

Breast Neoplasms

14,825 studies on the registry are indexed under Breast Neoplasms; 3,319 are open to participants now.

Browse Breast Neoplasms studies →

Open to participants now

71 of the 390 studies in Breast Neoplasms with a site in Netherlands are open now. Recruiting first, the newest first:

66 more — sign in →

All 71 open studies →

A study can be open while its sites in Netherlands have not opened yet or have stopped. Only those recruiting at a site in Netherlands →

Who these studies take

Of the 2,400 Breast Neoplasms studies recruiting now, 1,572 (66%) set no upper age limit and 591 (25%) stop at 75 or younger; 103 take children under 18; 214 take healthy volunteers.

This study: 18 Years and older · female · no healthy volunteers.

The full table on the hub →

This tab as a report to print or save as PDF → With an account.

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Watch this landscapeDownload CSVNarrow it in search →With an account: a weekly mail of what changed among 390 studies in Breast Neoplasms with a site in Netherlands, or all of them as a file.
02

Study summary

Given the uncertain benefit in efficacy of adding CDK 4/6 to first rather than second line endocrine treatment, the aim of this project is to evaluate whether the sequence of an aromatase inhibitor plus CDK 4/6 in first line followed by fulvestrant in second line is superior to the sequence of an aromatase inhibitor in first line followed by fulvestrant plus CDK4/6 in second line.

Read the detailed description

Combining cyclin-dependent kinases 4 and 6 (CDK 4/6) inhibitors with endocrine therapies in hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer has shown to result in substantial improvements in progression-free survival. There is however no evidence that this combination strategy leads to an improved overall survival. Furthermore, no specific subgroups that will or will not benefit from the combination of drugs have been identified yet. This means the optimal strategy for deploying CDK 4/6 inhibitors in clinical practice is not yet known. Since CDK 4/6 inhibitors are costly and can have toxic effects, it is important to determine the optimal treatment strategy to avoid both over- and undertreatment.

The SONIA-trial is an investigator-initiated, multicenter, randomized phase III study. The primary objective of this study is to evaluate if treatment with a non-steroidal aromatase inhibitor combined with CDK 4/6 inhibition in first line followed at progression by fulvestrant in second line (strategy A) improves progression-free survival compared to treatment with a non-steroidal aromatase inhibitor in first line followed at progression by fulvestrant combined with CDK4/6 inhibition in second line (strategy B). The primary end point is progression-free survival after two lines (PFS2), secondary end points include overall survival, quality of life, safety and biomarker analyses.

03

Conditions studied

  • Breast Neoplasm Female

Browse trials for

Keywords

  • CDK 4/6 inhibitor
04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
Female
Accepts healthy volunteers
No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  1. Adult women (≥ 18 years of age) with proven diagnosis of adenocarcinoma of the breast with evidence of loco-regional recurrent or disease not amenable to resection or radiation therapy with curative intent and for whom chemotherapy is not clinically indicated.
  2. Documentation of or cytologically confirmed diagnosis of estrogen-receptor (ER) expression >10% and/or progesterone receptor (PR) expression >10% breast cancer based on local laboratory results.
  3. Previously untreated with any systemic anti-cancer therapy for loco-regional recurrent or metastatic HR+ disease, with the exception of recently started (within 28 days of randomization) endocrine therapy.
  4. Women who are not must use LHRH agonist. Postmenopausal status is defined as:

    1. prior bilateral surgical oophorectomy, or
    2. spontaneous cessation of regular menses for at least 12 consecutive months without OAC
    3. in case of doubt serum estradiol \<20 umol/l and follicle stimulating hormone (FSH) levels >15 IU/L at screening
  5. Measurable or evaluable disease as defined per v.1.1 (see Appendix 3) or bone-only disease. Tumor lesions previously irradiated or subjected to other locoregional therapy will only be deemed measurable if disease progression at the treated site after completion of therapy is clearly documented.
  6. (ECOG) performance status (PS) 0-2.
  7. Adequate organ and marrow function defined as follows:

    1. ≥1,000/mm3 (1.0 x 10e9 /L);
    2. ≥50,000/mm3 (50 x 10e9 /L);
    3. Estimated ≥ 30 mL/min as calculated using the method standard for the institution;
    4. Total serum ≤1.5 x (≤3.0 x ULN if Gilbert's disease);
    5. and ALT ≤3 x ULN (≤5.0 x ULN if liver metastases present);
  8. Resolution of all acute toxic effects of prior anti-cancer therapy or surgical procedures to version 4.0 Grade ≤1, except alopecia or other toxicities not considered a safety risk for the patient at investigator's discretion.
  9. Willingness and ability to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures.
  10. Evidence of a personally signed and dated document indicating that the patient (or a legal representative) has been informed of all pertinent aspects of the study before any study-specific activity is performed.

Exclusion criteria

Exclusion Criteria:

  1. Patients with advanced, symptomatic, visceral spread, who are at risk of life-threatening complications in the short term (including patients with massive uncontrolled effusions (pleural, pericardial, peritoneal), pulmonary lymphangitis, and over 50% liver involvement).
  2. Known active uncontrolled or symptomatic , carcinomatous meningitis, or as indicated by clinical symptoms, cerebral edema, and/or progressive growth. Patients with a history of CNS metastases or cord compression are eligible if they have been definitively treated with local therapy (e.g., radiotherapy, stereotactic surgery) and are clinically stable without the use of for at least 4 weeks before randomization
  3. Prior or adjuvant treatment with an aromatase inhibitor (i.e., anastrozole, letrozole or exemestane) with disease recurrence while on or within 12 months of treatment.
  4. Prior treatment with any CDK4/6 inhibitor.
  5. Patients treated within the last 7 days prior to randomization with:

    1. Food or drugs that are known to be inhibitors (ie, amprenavir, atazanavir, boceprevir, clarithromycin, conivaptan, delavirdine, diltiazem, erythromycin, fosamprenavir, indinavir, itraconazole, ketoconazole, lopinavir, mibefradil, miconazole, nefazodone, nelfinavir, posaconazole, ritonavir, saquinavir, telaprevir, telithromycin, verapamil, voriconazole, and grapefruit or grapefruit juice);
    2. Drugs that are known to be CYP3A4 inducers (ie, carbamazepine, felbamate, nevirapine, phenobarbital, phenytoin, primidone, rifabutin, rifampin, rifapentin, and St. John's wort).
  6. Major surgery, chemotherapy, radiotherapy, any agents, or other anti-cancer therapy within 2 weeks before randomization. Patients who received prior radiotherapy to ≥25% of bone marrow are not eligible independent of when it was received.
  7. Diagnosis of any other prior to randomization, except those that are not believed to influence the patient's prognosis and do not require any further treatment. This includes, but is not limited to adequately treated basal cell or squamous cell skin cancer and carcinoma in situ of the cervix.
  8. >480 msec at baseline
  9. Active inflammatory bowel disease or chronic diarrhea, short bowel syndrome, or any upper gastrointestinal surgery including gastric resection.
  10. Known to letrozole or anastrozole, or any of its , or to any palbociclib excipients.
  11. Other severe acute or chronic medical or psychiatric condition or laboratory abnormality that may increase the risk associated with study participation or investigational product administration or may interfere with the interpretation of study results and, in the judgment of the investigator, would make the patient inappropriate for entry into this study.
  12. Recent or active suicidal ideation or behavior.
Terms in these criteria, in plain language(23)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Metastases

Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.

Histologically or cytologically confirmed

The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).

Your pathology report is the document that shows this.

Postmenopausal

Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).

RECIST

The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.

“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.

ECOG performance status

A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.

0
Fully active, no restrictions.
1
Limited in strenuous activity, but walking and able to do light work, such as housework or office work.
2
Walking and able to look after yourself, but unable to work; up and about more than half of waking hours.
3
Able to look after yourself only in part; in bed or a chair more than half of waking hours.
4
Unable to look after yourself at all; in bed or a chair all day.

Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.

Absolute neutrophil count (ANC)

The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.

It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.

Platelets

Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.

Creatinine clearance (CrCl)

How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.

Bilirubin

A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.

Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.

ULN (upper limit of normal)

The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.

“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.

ALT and AST (liver enzymes)

Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.

Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.

CTCAE grade

The US National Cancer Institute’s scale of how severe an adverse event is — any unwanted medical event during a study, such as a symptom, an illness or an abnormal test result, whether or not a treatment caused it. Whether it did is judged separately.

1
Mild.
2
Moderate.
3
Severe.
4
Life-threatening.
5
Death due to the event.

“Side effects of earlier treatment resolved to grade 1 or less” means they have settled to mild or gone.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

Brain metastases

Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).

Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.

Leptomeningeal disease

Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.

Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.

Corticosteroids (steroids)

Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.

Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.

Adjuvant and neoadjuvant

Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.

CYP3A (CYP3A4) inhibitors and inducers

CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.

Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.

Investigational drug or device

A drug or device being studied in a clinical trial.

It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.

Cancer (malignancy)

Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.

Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.

QT and QTc

On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.

The study may name a correction formula and a limit in milliseconds, often around 450–480.

Hypersensitivity

An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.

Excipients

The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.

05

Study design

Phase
Phase 3
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
None (open label)
Enrollment
1,050 participants (actual)

Study arms

  • Active comparator
    Strategy A CDK4/6 inhibitor in 1st line

    Non-steroidal aromatase inhibitor (letrozole or anastrozole, at the discretion of the treating physician) plus CDK4/6 inhibitor (palbociclib, ribociclib or abemaciclib, depending on availability and physician's preference) in first line followed by fulvestrant in second line.

    Drug: CDK 4/6 inhibitor · Drug: Non-Steroidal Aromatase Inhibitor · Drug: Fulvestrant

  • Active comparator
    Strategy B CDK4/6 inhibitor in 2nd line

    Non-steroidal aromatase inhibitor (letrozole or anastrozole, at the discretion of the treating physician) in first line followed by fulvestrant plus CDK4/6 inhibitor in second line (palbociclib, ribociclib or abemaciclib, depending on availability and physician's preference).

    Drug: CDK 4/6 inhibitor · Drug: Non-Steroidal Aromatase Inhibitor · Drug: Fulvestrant

Interventions

  • DrugCDK 4/6 inhibitor

    Adding CDK 4/6 inhibitor (pabociclib, ribociclib or abemaciclib depending on availability and physician's preference) to either first line treatment (with non-steroidal aromatase inhibitors, either letrozole or anastrozole) or second line treatment (with fulvestrant) in advanced HR+/HER2-negative breast cancer

    Also known as: palbociclib,Ibrance,ribociclib,Kisqali,abemaciclib,Verzenio

  • DrugNon-Steroidal Aromatase Inhibitor

    Adding CDK 4/6 inhibitor (pabociclib, ribociclib or abemaciclib depending on availability and physician's preference) to either first line treatment (with non-steroidal aromatase inhibitors, either letrozole or anastrozole) or second line treatment (with fulvestrant) in advanced HR+/HER2-negative breast cancer

    Also known as: NSAI, letrozole, Femara®, anastrozole, Arimidex®

  • Adding CDK 4/6 inhibitor (pabociclib, ribociclib or abemaciclib depending on availability and physician's preference) to either first line treatment (with non-steroidal aromatase inhibitors, either letrozole or anastrozole) or second line treatment (with fulvestrant) in advanced HR+/HER2-negative breast cancer

    Also known as: SERD, Faslodex®

This study also gives Palbociclib, Ribociclib, Abemaciclib, Anastrozole. No intervention listed here names it: that was found by reading the record.

06

What researchers measure

Primary outcomes

  1. PFS2

    Progression-free survival after two lines of treatment (PFS2)

    Time frame: Until objective disease progression, symptomatic deterioration, or unacceptable toxicity on second line treatment, death, strategy violation, or withdrawal of consent, whichever occurs first, assessed up to 60 months

Secondary outcomes

  1. OS

    Overall survival

    Time frame: Date of randomization until date of death due to any cause, assessed up to 60 months

  2. FACT-B questionnaire

    Quality of Life questionnaire

    Time frame: Questionnaires will be administered at baseline and thereafter every three months, up to 60 months

  3. EQ-5D questionnaire

    Quality of Life questionnaire

    Time frame: Questionnaires will be administered at baseline and thereafter every three months, up to 60 months

  4. iMTA RUQ-B questionnaire

    Quality of Life questionnaire

    Time frame: Questionnaires will be administered at baseline and thereafter every six months, up to 60 months

  5. Number of participants with grade 3 or 4 treatment-related neutropenia as assessed by CTCAE v4.0

    Safety assessment will consist of monitoring of all grade 3 and grade 4 neutropenia (absolute neutrophil count/L)

    Time frame: Through study completion, assessed up to 60 months

  6. Number of participants with grade 3 or 4 treatment-related thrombocytopenia as assessed by CTCAE v4.0

    Safety assessment will consist of monitoring of all grade 3 and grade 4 thrombocytopenia (platelet count/L)

    Time frame: Through study completion, assessed up to 60 months

  7. Number of participants with grade 3 or 4 treatment-related anemia as assessed by CTCAE v4.0

    Safety assessment will consist of monitoring of all grade 3 and grade 4 anemia (mmol/L)

    Time frame: Through study completion, assessed up to 60 months

  8. Number of participants with grade 3 or 4 treatment-related elevated liver enzymes (ALAT/ASAT/AF/GGT/bilirubin) as assessed by CTCAE v4.0

    Safety assessment will consist of monitoring of all grade 3 and grade 4 elevated liver enzymes (elevation compared to upper limit of normal)

    Time frame: Through study completion, assessed up to 60 months

  9. Number of participants with grade 3 or 4 treatment-related other toxicities as defined in CTCAE v4.0

    Safety assessment will consist of monitoring of all grade 3 and grade 4 other toxicities as defined in CTCAE v4.0

    Time frame: Through study completion, assessed up to 60 months

  10. Cost-effectiveness by means of a decision model (a multistate Markov model or a Discrete Event Simulation model)

    The cost and outcomes of both arms will be assessed by means of a decision model (a multistate Markov model or a Discrete Event Simulation model). Cost-effectiveness will be determined by comparing costs and effects of both treatment strategies. Quality adjusted life years will be computed by multiplying life-years with the observed utility scores during those life years. The friction cost method will be used for estimating the societal costs of productivity losses. Unit costs for drugs will be derived from www.medicijnkosten.nl or the Z-index. The costs of a hospital day, outpatient visit, and day care treatment, will be based on the Dutch costing manual. Other costs will be collected from NZA tariffs. All costs will be expressed in Euros.

    Time frame: At 60 months after entry into the study

  11. ORR

    Objective response rate

    Time frame: Through study completion, assessed up to 60 months

  12. Plasma through levels

    Plasma through levels of CDK4/6 inhibitor measured in blood samples obtained at cycle 1, day 15 (of 28 days in one cycle) and at cycle 2, day 15 in participants treated with CDK4/6 inhibitors.

    Time frame: Through study completement

  13. Pharmacogenomics

    DNA sequencing in a blood sample obtained at cycle 1, day 15 (of 28 days in one cycle) of treatment with CDK4/6 inhibitor.

    Time frame: On day 15 of cycle 1 (a cycle is 28 days)

  14. Liquid biopsies

    Circulating tumor DNA isolated from blood samples collected at 7 timepoints during the study. Mutation level during the study and at disease progression will be compared to base-line mutation level.

    Time frame: At baseline of first line, at cycle 1 day 15 (a cycle is 28 days), at cycle 4 day 1, at baseline of second line, at cycle 1 day 15 (a cycle is 28 days), at cycle 4 day 1 and at disease progression

  15. Tissue microarray

    Tissue microarray on archived FFPE tissue blocks of the tumor

    Time frame: At baseline

07

Study locations

72 sites
08

References and documents

Publications

  • Wortelboer N, van Ommen-Nijhof A, Konings IR, van der Noort V, van den Pol E, Guerrero Paez C, Bakker SD, Hovenga S, Imholz ALT, Kamm YJL, van Leeuwen L, Luykx-de Bakker SA, Mandigers CMPW, van Riel JMGH, Tol J, van de Wouw AJ, Wilting SM, van Leeuwen-Stok AE, Jager A, Sonke GS. Overall Survival With First-Line vs Second-Line CDK4/6 Inhibitor Use in Advanced Breast Cancer: A Randomized Clinical Trial. JAMA Oncol. 2026 Apr 1;12(4):375-383. doi: 10.1001/jamaoncol.2025.6585. PubMed 41712229 ↗
  • Wortelboer N, Kent S, Blommestein HM, van Ommen-Nijhof A, van der Noort V, van den Pol E, Paez CG, Beeker A, Beelen K, Hamming LC, Heijns JB, Honkoop AH, de Jong PC, van Rossum-Schornagel QC, van Schaik-van de Mheen C, Tol J, Tromp-van Driel CS, Vrijaldenhoven S, van Leeuwen-Stok AE, Sonke GS, Jager A, Konings IR. Health-related quality of life with first- vs second-line CDK4/6 inhibitor use in advanced breast cancer: results from the SONIA trial. J Natl Cancer Inst. 2026 Mar 1;118(3):502-510. doi: 10.1093/jnci/djaf334. PubMed 41270788 ↗
  • Wortelboer N, Kent S, Konings IR, van Ommen-Nijhof A, van der Noort V, van den Pol E, Guerrero Paez C, van Bekkum ML, van den Berkmortel FWPJ, Droogendijk HJ, Houtsma D, Oosterkamp HM, van der Padt-Pruijsten A, Siemerink EJM, Tol J, van Zweeden AA, van Leeuwen-Stok AE, Sonke GS, Jager A, Blommestein HM. Health economic outcomes and costs of CDK4/6 inhibitor use in first- versus second-line for advanced breast cancer: A cost-effectiveness analysis of the phase 3 SONIA trial. Eur J Cancer. 2025 Dec 9;231:116051. doi: 10.1016/j.ejca.2025.116051. Epub 2025 Oct 25. PubMed 41207182 ↗
  • Jongbloed EM, Wortelboer N, de Weerd V, Beaufort CM, Ruigrok-Ritstier K, Van MN, Kraan J, van Zweeden AA, van der Padt-Pruijsten A, Hamming LC, Konings IR, Sonke GS, Oomen-de Hoop E, Martens JWM, Jager A, Wilting SM. Early versus deferred use of CDK4/6 inhibitors in advanced breast cancer: circulating tumor DNA analysis of a randomized phase 3 trial. Nat Med. 2025 Nov;31(11):3662-3667. doi: 10.1038/s41591-025-03935-w. Epub 2025 Sep 4. PubMed 40908356 ↗
  • van Ommen-Nijhof A, Konings IR, van Zeijl CJJ, Uyl-de Groot CA, van der Noort V, Jager A, Sonke GS; SONIA study steering committee. Selecting the optimal position of CDK4/6 inhibitors in hormone receptor-positive advanced breast cancer - the SONIA study: study protocol for a randomized controlled trial. BMC Cancer. 2018 Nov 20;18(1):1146. doi: 10.1186/s12885-018-4978-1. PubMed 30458732 ↗

Individual participant data

Plan to share: No — Individual participant data will not be shared with other researchers.

09

Timeline

Tracking since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reachedSimilar studies: half by the dot; the band is the middle halfHalf of similar studies reached it by the dot; the band is the middle half, from a quarter to three quarters

Ran from Nov 2017 to primary completion in Mar 2023, 63 months.

Of 328 non-industry phase 3 interventional studies under Breast Neoplasms, half reached primary completion within 79 months of starting (the median), counting those still running; a quarter within 50 and three quarters within 127. This study's 63 months is below that.

Counting every sponsor, half of 600 studies reached it within 59 months; a quarter within 36 and three quarters within 96.

How these figures are worked out, and which studies are left out of them.

Registered
Jun 15, 2017
First posted
Feb 8, 2018
StartActual
Nov 9, 2017
Primary completionActual
Mar 6, 2023
CompletionEst.
Dec 2028
Last update
May 20, 2026
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
No changes since tracking began. The registry record was last updated on May 20, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT03425838
Lead sponsor
Borstkanker Onderzoek Groep
Responsible party
Sponsor
First posted
Feb 8, 2018
Start date
Nov 9, 2017
Primary completion
Mar 6, 2023
Completion
Dec 2028 (estimated)
Last update
May 20, 2026

Study contacts

A. Jager, MD, PhD
principal investigator · Borstkanker Onderzoek Groep
A E van Leeuwen-Stok, PhD
study director · BOOG Study Center

Oversight

Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is active, not recruiting, as verified in Sep 2025. You cannot join it, but the record below documents what was studied.

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Discussion

Questions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.

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Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.

Studies of the drugs tested here: Palbociclib · Ribociclib

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