From the Guidelines
Palbociclib and ribociclib should not be given in the same line of treatment as they are both CDK4/6 inhibitors with similar mechanisms of action. The use of these medications in the same line of treatment is not supported by clinical evidence, and their sequential use in second-line therapy after one has failed is also generally not recommended due to cross-resistance [ESMO-MCBS v1.1 scores: 3-5] 1.
When considering treatment options for patients with metastatic breast cancer, it is essential to prioritize the use of CDK4/6 inhibitors in combination with endocrine therapy (ET) as the standard-of-care for ER-positive, HER2-negative MBC, given their improved progression-free survival (PFS) and overall survival (OS) and good toxicity profile [I, A; 1].
Key points to consider in treatment decisions include:
- CDK4/6 inhibitors are effective in de novo or recurrent MBC, in cases of primary or secondary endocrine resistance, in postmenopausal or premenopausal women, and in men [the latter with a luteinising hormone-releasing hormone (LH-RH) agonist] 1.
- For patients who did not relapse on an aromatase inhibitor (AI), or within 12 months of stopping adjuvant AI, a CDK4/6 inhibitor in combination with an AI is advised 1.
- In patients who relapsed on adjuvant AI therapy, or within 12 months of stopping adjuvant AI, a CDK4/6 inhibitor in combination with fulvestrant is advised [ESMO-MCBS v1.1 score: 4; 1].
- The toxicity profiles of CDK4/6 inhibitors are slightly different, and patients who develop severe toxicity characteristic of one CDK4/6 inhibitor may switch to a different CDK4/6 inhibitor 1.
After progression on a CDK4/6 inhibitor-based regimen, treatment should be changed to a different class of medications, taking into account the individual patient's disease characteristics, prior treatments, response patterns, and tolerability considerations 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Treatment Options for Metastatic Breast Cancer
- Palbociclib and ribociclib are CDK4/6 inhibitors used in the treatment of hormone receptor-positive metastatic breast cancer 2, 3, 4.
- These medications can be used in combination with an aromatase inhibitor or fulvestrant, and have shown significant increases in progression-free survival in clinical trials 3, 4.
Sequential Treatment
- A study comparing ribociclib and palbociclib as second-line treatments in combination with fulvestrant found similar clinical benefits and toxicity profiles for both medications 5.
- The study suggested that both ribociclib and palbociclib can be effective as second-line treatments, with no significant difference in progression-free survival or overall response rate 5.
Combination Therapy
- There is limited evidence on the use of palbociclib and ribociclib in the same line of treatment, as they are typically used sequentially or in different treatment settings 2, 3.
- However, a consensus workshop on the management of concomitant medication with CDK4/6 inhibitors suggested that certain medications can be safely administered concomitantly with palbociclib and/or ribociclib 6.