The first 60 days: HR-positive metastatic breast cancer after CDK4/6 inhibitors
When hormone-positive breast cancer grows through a CDK4/6 inhibitor, a blood test picks the next drug. Tumours with an acquired ESR1 mutation respond to the oral degraders elacestrant, camizestrant and imlunestrant; tumours with PIK3CA, AKT1 or PTEN changes to capivasertib, inavolisib or alpelisib; and once endocrine options run out, antibody-drug conjugates come before chemotherapy. Below, week by week, is what OnCo's record of HR-positive metastatic breast cancer after CDK4/6 inhibitors says about the first two months: the order is typical, the timing is yours to ask about. Sections appear only where the record has something to say. Orientation, not medical advice.
What happens now
Staging tests establish exactly what and where the cancer is. Everything else follows from the answers.
Ask which of these were tested and what the results were; see the report reader for what each value means.
These specialties appear in the standard of care for this cancer. In most centres they meet weekly as a tumour board to agree each plan; you can ask when yours was discussed and what was decided.
- PathologistNamed in the standard of care for: ESR1-mutant disease after a CDK4/6 inhibitor.
- Medical oncologistNamed in the standard of care for: ESR1-mutant disease after a CDK4/6 inhibitor, PIK3CA, AKT1 or PTEN alteration, No targetable alteration, Endocrine-refractory, HER2-low or ultralow and 1 more.
A second opinion from a centre that treats many similar cases is normal, not rude; the standard of care tells you what to compare it against.
Each row is a setting from the standard of care, in the order it usually arises. Not all will apply to you; your stage and biomarkers decide which do. The guideline grade, where recorded, says how strong the evidence is.
Elacestrant (EMERALD), imlunestrant (EMBER-3) or vepdegestrant; where available, a switch to camizestrant at the moment ESR1 appears in plasma while continuing the CDK4/6 inhibitor (SERENA-6).
Capivasertib with fulvestrant (CAPItello-291); alpelisib with fulvestrant for PIK3CA (SOLAR-1); inavolisib with palbociclib and fulvestrant for PIK3CA-mutant disease relapsing during or soon after adjuvant endocrine therapy (INAVO120).
Fulvestrant with abemaciclib (postMONARCH), everolimus with exemestane, or another endocrine agent; giredestrant with everolimus is emerging (evERA).
Olaparib (OlympiAD) or talazoparib (EMBRACA) in place of chemotherapy.
Trastuzumab deruxtecan before chemotherapy (DESTINY-Breast06), then sacituzumab govitecan (TROPiCS-02) or datopotamab deruxtecan (TROPION-Breast01) after chemotherapy.
Generated from this cancer's standard of care, biomarkers and open problems. Take the group that matches where you are. To tick, add your own and print, open the one-page appointment sheet.
Newly diagnosed
- What is my exact diagnosis, stage, and grade, and which tests established them?Everything else follows from an accurate stage and subtype.
- Which biomarkers have been tested on my tumour (for example ESR1 mutation on circulating tumour DNA, retested at each progression, PIK3CA, AKT1 and PTEN alterations on tissue or plasma, HER2 immunohistochemistry score, Oestrogen receptor persistence on rebiopsy of a metastasis, Germline BRCA1 and BRCA2), and what were the results?These results decide eligibility for targeted therapy, immunotherapy, and trials.
- Which subtype is my cancer, and does that change the recommended treatment?Recognised subtypes for this cancer include ESR1-mutant disease acquired under aromatase inhibitors, PIK3CA-mutant luminal disease, AKT1-mutant or PTEN-altered disease.
- Is germline (inherited) genetic testing recommended for me or my family?Inherited variants can change treatment and matter for relatives.
ESR1-mutant disease after a CDK4/6 inhibitor
- For my situation (esr1-mutant disease after a cdk4/6 inhibitor), which of the standard options do you recommend and why?Guideline options include: Elacestrant (EMERALD), imlunestrant (EMBER-3) or vepdegestrant; where available, a switch to camizestrant at the moment ESR1 appears in plasma while continuing the CDK4/6 inhibitor (SERENA-6).
- Am I a candidate for Elacestrant, Imlunestrant, Camizestrant or related drugs, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of EMERALD and EMBER-3 apply to someone like me?Trial populations differ from individual patients; ask how closely you match.
PIK3CA, AKT1 or PTEN alteration
- For my situation (pik3ca, akt1 or pten alteration), which of the standard options do you recommend and why?Guideline options include: Capivasertib with fulvestrant (CAPItello-291); alpelisib with fulvestrant for PIK3CA (SOLAR-1); inavolisib with palbociclib and fulvestrant for PIK3CA-mutant disease relapsing during or soon after adjuvant endocrine therapy (INAVO120).
- Am I a candidate for Capivasertib, Alpelisib, Inavolisib or related drugs, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of CAPItello-291 and SOLAR-1 apply to someone like me?Trial populations differ from individual patients; ask how closely you match.
No targetable alteration
- For my situation (no targetable alteration), which of the standard options do you recommend and why?Guideline options include: Fulvestrant with abemaciclib (postMONARCH), everolimus with exemestane, or another endocrine agent; giredestrant with everolimus is emerging (evERA).
- Am I a candidate for Abemaciclib, Everolimus, Exemestane, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of postMONARCH and evERA apply to someone like me?Trial populations differ from individual patients; ask how closely you match.
Endocrine-refractory, HER2-low or ultralow
- For my situation (endocrine-refractory, her2-low or ultralow), which of the standard options do you recommend and why?Guideline options include: Trastuzumab deruxtecan before chemotherapy (DESTINY-Breast06), then sacituzumab govitecan (TROPiCS-02) or datopotamab deruxtecan (TROPION-Breast01) after chemotherapy.
- Am I a candidate for Trastuzumab deruxtecan, Sacituzumab govitecan, Datopotamab deruxtecan, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of DESTINY-Breast06 and TROPiCS-02 apply to someone like me?Trial populations differ from individual patients; ask how closely you match.
Germline BRCA carriers
- For my situation (germline brca carriers), which of the standard options do you recommend and why?Guideline options include: Olaparib (OlympiAD) or talazoparib (EMBRACA) in place of chemotherapy.
- Am I a candidate for Olaparib, Talazoparib, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
- How do the results of OlympiAD and EMBRACA apply to someone like me?Trial populations differ from individual patients; ask how closely you match.
Any stage
- Are there clinical trials I could join, for example of Vepdegestrant, Gedatolisib, Giredestrant, Camizestrant?Trials are how the next standard of care is set; asking early keeps options open.
- Would a second opinion at a high-volume centre change anything, and can you help arrange it?Rare or high-stakes decisions benefit from a centre that treats many similar patients.
- What supportive care (symptom control, nutrition, exercise, mental health, financial help) is available from the start?Supportive care improves quality of life and helps patients complete treatment.
- I read that “No trial has compared the sequence of oral SERD, pathway inhibitor and antibody-drug conjugate”. How does that affect my plan?Open problems are where trials and second opinions matter most.
- I read that “Whether to continue a CDK4/6 inhibitor after progression gives small gains and it is unclear for whom”. How does that affect my plan?Open problems are where trials and second opinions matter most.
Trials open now for this cancer in OnCo, largest phase first. Joining a trial is a decision like any other: ask what the comparison arm is, whether a placebo is used, and what happens if you leave. The cancer page searches ClinicalTrials.gov live for more.
- A Study of Tersolisib (LY4064809/STX-478) With Other Anti-Cancer Treatments in Participants With Advanced Breast Cancer With a Genetic Change (PIK3CA)Phase 3 · recruiting · NCT07174336A Phase 2, Randomized, Open-Label Dose Optimization and Phase 3, Randomized, Double-Blind, Placebo-Controlled Study of LY4064809 Combined With a CDK4/6 Inhibitor and Endocrine Therapy in Adults With HR+, HER2-Advanced Breast Cancer With a PIK3CA Mutation Who Received No Prior Treatment for Advanced Breast Cancer (PIKALO-2)
- CAMBRIA-1 & CAMBRIA-2Phase 3 · active · NCT05952557Adjuvant ER+/HER2- early breast cancer: camizestrant vs standard endocrine therapy, either after 2-5 years of prior ET (CAMBRIA-1) or upfront (CAMBRIA-2)
Much of what helps in the first weeks is free if you know to ask: testing, helplines, rides and lodging, second opinions, trial travel.
- HR-positive metastatic breast cancer after CDK4/6 inhibitors: the full pageWhen hormone-positive breast cancer grows through a CDK4/6 inhibitor, a blood test picks the next drug. Tumours with an acquired ESR1 mutation respond to the oral degraders elacestrant, camizestrant and imlunestrant; tumours with PIK3CA, AKT1 or PTEN changes to capivasertib, inavolisib or alpelisib; and once endocrine options run out, antibody-drug conjugates come before chemotherapy.
- One-page appointment sheetYour questions, the words you may hear, what to bring, and space for the answers. Print it.
- Treatment sequencingWhich treatment tends to follow which, line by line.
- NavigatorStandard of care for your stage, what you have tried, and trials near you.
- HER2-low and HER2-ultralow: Tumours with a little HER2 (IHC 1+ or 2+ without amplification), or a trace (ultralow), which older HER2 drugs ignored but Enhertu can attack.
- Germline BRCA mutation (gBRCA): An inherited fault in the BRCA1 or BRCA2 gene, present in every cell from birth, that greatly raises the risk of breast, ovarian, prostate and pancreatic cancer and makes those cancers sensitive to PARP inhibitors and platinum.
Every term links to the glossary.