Circulating Tumor DNA (ctDNA)-Guided Late-Line Treatment in Patients With Late-Stage Breast Cancer

Study Overview
=================
Brief Summary
-----------------
This is a retrospective, observational, multi-center clinical study of circulating tumor DNA (ctDNA) to guide late-line therapy in late-stage metastatic breast cancer patients.

Detailed Description
-----------------
This study aims to evaluate the feasibility of plasma ctDNA mutation in guiding late-line treatment for late-stage metastatic breast cancer patients. Meanwhile, this study tries to evaluate the curative effect of ctDNA subtype-guided late-line therapy.

Official Title
-----------------
Clinical Application of Circulating Tumor DNA (ctDNA) to Guided the Late-Line Treatment for Patients With Late-Stage Breast Cancer

Conditions
-----------------
Metastatic Breast Cancer, Circulating Tumor DNA, Gene Abnormality

Intervention / Treatment
-----------------
* Drug: Control group
* Drug: Case group


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Recent progression of TNBC after multiple lines of chemotherapy or of HR+ or HER2+ MBC after multiple lines of endocrine or targeted therapy; No available recommendation for the next treatment regimen; An Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2; An updated, available pathological HR/HER2 status for metastasis; According to RECIST 1.1 standard, there should be at least one measurable target lesion; The expected survival time is > 3 months; Those aged 18-70 years old; Liver and kidney function and blood routine test meet the following conditions: Neutrophil > 2.0g/l, Hb > 9g / L, PLT > 100g / L; ALT and AST < 2.5ULN; TBIL < 1.5ULN; Cr < 1.0ULN Signing informed consent; Those willing to accept polygenic testing. Exclusion Criteria: Patients with multiple primary tumors; Those who are unable to obtain blood samples; Those with a history of immunodeficiency or organ transplantation; Those with abnormal cardiac function or previous history of myocardial infarction or serious arrhythmia; The researchers think it is not suitable to participate in this experiment.

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
-----------------
Female

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Control group<br>Control group includes patients without ctDNA abnormality and patients without druggable ctDNA abnormality. | Drug: Control group<br>* Physician chosen treatment<br>|
| Case group<br>Case group includes patients with druggable ctDNA abnormality. | Drug: Case group<br>* Druggable ctDNA alterations-guided therapy<br>* Other names: HDAC inhibitor;|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Disease Control Rate (DCR) | The total rate of CR+PR+SD after the completion of two cycles of late-line therapy. | From the beginning of the treatment to the end of Cycle 2 (each cycle is 28 days) of treatment. | 
| Progression-Free Survival | The survival time between the beginning of treatment to death or the progression. | From date of recruitment until the date of first documented progression or date of death from any cause, whichever came first, assessed up to 12 months. |