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

  • End date
    Oct 30, 2022
  • participants needed
  • sponsor
    Borstkanker Onderzoek Groep
Updated on 30 July 2021
breast cancer
endocrine therapy
gilbert's syndrome
liver metastases
cancer treatment
aromatase inhibitor
lhrh agonist


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.


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.

Condition Breast Neoplasm Female
Treatment fulvestrant, CDK 4/6 inhibitor, Non-Steroidal Aromatase Inhibitor
Clinical Study IdentifierNCT03425838
SponsorBorstkanker Onderzoek Groep
Last Modified on30 July 2021


Yes No Not Sure

Inclusion Criteria

Adult women ( 18 years of age) with proven diagnosis of adenocarcinoma of the breast with evidence of loco-regional recurrent or metastatic disease not amenable to resection or radiation therapy with curative intent and for whom chemotherapy is not clinically indicated
Documentation of histologically or cytologically confirmed diagnosis of estrogen-receptor (ER) expression >10% and/or progesterone receptor (PR) expression >10% breast cancer based on local laboratory results
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
Women who are not post-menopausal must use LHRH agonist. Postmenopausal status is defined as
prior bilateral surgical oophorectomy, or
spontaneous cessation of regular menses for at least 12 consecutive months without OAC
in case of doubt serum estradiol <20 umol/l and follicle stimulating hormone (FSH) levels >15 IU/L at screening
Measurable or evaluable disease as defined per RECIST 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
Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-2
Adequate organ and marrow function defined as follows
ANC 1,000/mm3 (1.0 x 10e9 /L)
Platelets 50,000/mm3 (50 x 10e9 /L)
Estimated creatinine clearance 30 mL/min as calculated using the method standard for the institution
Total serum bilirubin 1.5 x ULN (3.0 x ULN if Gilbert's disease)
AST and ALT 3 x ULN (5.0 x ULN if liver metastases present)
Resolution of all acute toxic effects of prior anti-cancer therapy or surgical procedures to NCI CTCAE version 4.0 Grade 1, except alopecia or other toxicities not considered a safety risk for the patient at investigator's discretion
Willingness and ability to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures
Evidence of a personally signed and dated informed consent 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

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)
Known active uncontrolled or symptomatic CNS metastases, carcinomatous meningitis, or leptomeningeal disease 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 steroids for at least 4 weeks before randomization
Prior neoadjuvant or adjuvant treatment with an aromatase inhibitor (i.e., anastrozole, letrozole or exemestane) with disease recurrence while on or within 12 months of treatment
Prior treatment with any CDK4/6 inhibitor
Patients treated within the last 7 days prior to randomization with
Food or drugs that are known to be CYP3A4 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)
Drugs that are known to be CYP3A4 inducers (ie, carbamazepine, felbamate, nevirapine, phenobarbital, phenytoin, primidone, rifabutin, rifampin, rifapentin, and St. John's wort)
Major surgery, chemotherapy, radiotherapy, any investigational 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
Diagnosis of any other malignancy 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
QTc >480 msec at baseline
Active inflammatory bowel disease or chronic diarrhea, short bowel syndrome, or any upper gastrointestinal surgery including gastric resection
Known hypersensitivity to letrozole or anastrozole, or any of its excipients, or to any palbociclib excipients
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
Recent or active suicidal ideation or behavior
Clear my responses

How to participate?

Step 1 Connect with a study center
What happens next?
  • You can expect the study team to contact you via email or phone in the next few days.
  • Sign up as volunteer to help accelerate the development of new treatments and to get notified about similar trials.

You are contacting

Investigator Avatar

Primary Contact



Additional screening procedures may be conducted by the study team before you can be confirmed eligible to participate.

Learn more

If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

Learn more

Complete your scheduled study participation activities and then you are done. You may receive summary of study results if provided by the sponsor.

Learn more

Similar trials to consider


Browse trials for

Not finding what you're looking for?

Every year hundreds of thousands of volunteers step forward to participate in research. Sign up as a volunteer and receive email notifications when clinical trials are posted in the medical category of interest to you.

Sign up as volunteer

user name

Added by • 



Reply by • Private

Lorem ipsum dolor sit amet consectetur, adipisicing elit. Ipsa vel nobis alias. Quae eveniet velit voluptate quo doloribus maxime et dicta in sequi, corporis quod. Ea, dolor eius? Dolore, vel!

  The passcode will expire in None.

No annotations made yet

Add a private note
  • abc Select a piece of text from the left.
  • Add notes visible only to you.
  • Send it to people through a passcode protected link.
Add a private note