A Phase 2 interventional study of Palbociclib and Fulvestrant in Metastatic Breast Cancer, sponsored by ETOP IBCSG Partners Foundation. Completed at 19 sites in 3 countries. Open to female participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-08-26.
Sponsored by ETOP IBCSG Partners Foundation · Phase 2, Interventional, and Treatment
This international, multicenter, prospective single arm Phase II biomarker discovery clinical trial with the primary objective of assessing the association of PFS with gene mutations, gene copy number aberrations and gene signatures in post-menopausal women with hormone receptor positive, HER2-negative metastatic or locally relapsed breast cancer whose disease has progressed after prior adjuvant endocrine therapy or one line systemic treatment, i.e., endocrine treatment or chemotherapy, administered for metastatic disease.
Patients will be treated with the combination of palbociclib and fulvestrant. The primary objective is to assess the association of the primary endpoint progression-free survival (PFS) with potential markers.
The trial is included in the AURORA program conducted by the Breast International Group (BIG), an international study aiming to collect and characterize biological samples, including metastatic tissue, from patients with advanced breast cancer.
The primary aim of the PYTHIA study is to discover potentially innovative biomarkers for the selection of patients to Palbociclib/Fulvestrant treatment. The strength of the trial lies in its conduct in conjunction with the AURORA study, which systematically evaluates a panel of biomarkers in tissue and blood, in a certified central lab. Stemming from this association, an abundance of molecular profiling information will become available for different biological samples. Additional molecular and functional imaging assessments performed within the context of the PYTHIA study increase its scientific merit, since it will represent a prospective, systematic effort to identify biomarkers for patient stratification, integrating several molecular profiling assessments.
12,544 studies on the registry are indexed under Breast Neoplasms; 2,892 are open to participants now.
This study's enrollment of 124 is above the median of 72 across 9,303 interventional studies indexed under Breast Neoplasms.
Browse Breast Neoplasms studies →ETOP IBCSG Partners Foundation is the lead sponsor of 50 studies on the registry; 5 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Postmenopausal, defined as women with:
Endocrine resistant disease, defined as one of:
Note: Patient may have received one prior chemotherapy for advanced or metastatic breast cancer.
Hematological status:
Hepatic status:
Renal status:
- Creatinine ≤ 1.5 ×ULN or creatinine clearance > 60 ml/min.
Exclusion Criteria:
Palbociclib plus Fulvestrant
Drug: Palbociclib · Drug: Fulvestrant
125 mg, orally, daily for 3 weeks followed by 1 week off; repeated at every 28 days cycle until progression, lack of tolerability, or patient declines further protocol treatment.
Also known as: PD-0332991, Ibrance
500mg, intramuscularly on days 1 and 15 of cycle 1, then on day 1 (+/- 3 days) of every 28 days cycle until progression, lack of tolerability, or patient declines further protocol treatment.
Also known as: Faslodex
Number of Participants With and Without Progression Free Survival (PFS) Events
Time from treatment initiation until documented disease progression according to RECIST 1.1 or death, whichever occurs first
Time frame: Maximum 36 months
Best Overall Response
Best overall response is based on RECIST (Response evaluation criteria in solid tumors) 1.1 criteria and is defined as best response recorded from enrollment across all time points until disease progression. Confirmation of partial response (PR) or complete response (CR) by an additional scan was not requested in this trial (rationale: initially because of randomized placebo-controlled design; subsequently because no hypothesis testing of progression-free survival, PFS, distribution relative to an historical control).
Time frame: From date of enrolment until patient's end of treatment visit (or a maximum of 12 months after EoT in the absence of tumor progression), assessed up to 48 months.
Best Overall Response of Complete Response (CR) or Partial Response (PR) or Stable Disease (SD)
Disease control is defined as best overall response of complete response (CR) or partial response (PR), or stable disease (SD) (or non-CR/non-PD, progressive disease, in the case of non-measurable disease only) lasting for at least 24 weeks, measured from enrollment until first documentation of progressive disease
Time frame: From date of enrolment until patient's end of treatment visit (or a maximum of 12 months after EoT in the absence of tumor progression), assessed up to 48 months.
| Milestone | Experimental |
|---|---|
| Started | 124 |
| Completed | 122 |
| Not completed | 2 |
| Withdrew: Did not start protocol therapy | 1 |
| Withdrew: Patient determined to have triple-negative breast cancer, thus not having the target disease | 1 |
Time from treatment initiation until documented disease progression according to RECIST 1.1 or death, whichever occurs first
| Participants | Experimental |
|---|---|
| PFS event, Yes | 92 |
| PFS event, No | 30 |
Best overall response is based on RECIST (Response evaluation criteria in solid tumors) 1.1 criteria and is defined as best response recorded from enrollment across all time points until disease progression. Confirmation of partial response (PR) or complete response (CR) by an additional scan was not requested in this trial (rationale: initially because of randomized placebo-controlled design; subsequently because no hypothesis testing of progression-free survival, PFS, distribution relative to an historical control).
| Participants | Experimental |
|---|---|
| Complete response (CR) | 6 |
| Partial response (PR) | 20 |
| Stable disease (SD) | 80 |
| Progressive disease (PD) | 16 |
Disease control is defined as best overall response of complete response (CR) or partial response (PR), or stable disease (SD) (or non-CR/non-PD, progressive disease, in the case of non-measurable disease only) lasting for at least 24 weeks, measured from enrollment until first documentation of progressive disease
| Participants | Experimental |
|---|---|
| Disease control not observed | 33 |
| Disease control observed (CR or PR or SD) | 89 |
Collected over Maximum 36 months. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Experimental | 30/122 (24.6%) | 89/122 (73%) | 0/122 (0%) |
| Event | Experimental |
|---|---|
| Neutrophil count decreaseInvestigations | 87/122 |
| AnemiaGastrointestinal disorders | 2/122 |
Postmenopausal patients with endocrine-resistant metastatic or locally relapsed ER+/HER2- breast cancer not amenable to treatment with a curative intent.
| Age, Customized(Participants) | Experimental |
|---|---|
| <40 years | 2 |
| 40-49 years | 15 |
| 50-59 years | 37 |
| 60-69 years | 42 |
| 70-79 years | 23 |
| 80+ years | 3 |
| Sex: Female, Male(Participants) | Experimental |
|---|---|
| Female | 122 |
| Male | 0 |
| Race and Ethnicity Not Collected(Participants) | Experimental |
|---|
| Region of Enrollment(participants) | Experimental |
|---|---|
| Belgium | 73 |
| Italy | 46 |
| United Kingdom | 3 |
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This study is completed, as verified in Jul 2023. You cannot join it, but the record below documents what was studied.
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ETOP IBCSG Partners Foundation