From the Guidelines
Neoadjuvant pembrolizumab for breast cancer should be administered for 4-8 cycles, depending on the stage of the disease and the selected regimen, with each cycle given every 3 weeks. This recommendation is based on the most recent and highest quality evidence from the 2024 ESMO clinical practice guideline for diagnosis, treatment, and follow-up of early breast cancer 1. The guideline suggests that chemotherapy should be administered for 12-24 weeks (4-8 cycles) regardless of whether an immune checkpoint inhibitor (ICI) like pembrolizumab is added.
Key considerations for neoadjuvant pembrolizumab treatment include:
- The stage of the disease, with cT1c-4 N0, or any N-positive TNBC, being preferred for neoadjuvant treatment 1
- The type of selected regimen, which may include dose-dense schedules of chemotherapy with granulocyte colony-stimulating factor support 1
- The potential for immune-related adverse events, which requires close monitoring throughout treatment and follow-up 1
- The specific breast cancer subtype, such as triple-negative breast cancer (TNBC), which may benefit from the combination of pembrolizumab and chemotherapy 1
It's essential to note that pembrolizumab should be administered every 3 weeks throughout the neoadjuvant phase, and for nine 3-week cycles during the adjuvant phase, regardless of pathological complete response (pCR) status, as per the guideline recommendations 1. The treatment plan should be individualized based on the patient's response to treatment, tolerance of side effects, and specific disease characteristics.
From the Research
Neoadjuvant Pembrolizumab Cycles for Breast Cancer
- The optimal number of cycles for neoadjuvant pembrolizumab in breast cancer is not explicitly stated in the provided studies, but we can look at the treatment regimens used in these studies for guidance.
- In the study 2, patients received neoadjuvant pembrolizumab 200 mg or placebo every 3 weeks, given with paclitaxel every week for 12 weeks, followed by four cycles of doxorubicin or epirubicin plus cyclophosphamide.
- The study 3 involved neoadjuvant pembrolizumab 200 mg or placebo every 3 weeks, plus 4 cycles of paclitaxel plus carboplatin and then 4 cycles of doxorubicin (or epirubicin) plus cyclophosphamide.
- The real-world analysis 4 found that completion of at least 8 cycles of pembrolizumab was significantly associated with pathological complete response (pCR) in patients with triple-negative breast cancer.
- The phase 1b study 5 evaluated six pembrolizumab plus chemotherapy regimens, with all cohorts receiving a pembrolizumab 200-mg run-in dose, then eight cycles of pembrolizumab in combination with a taxane with or without carboplatin for 12 weeks, and then doxorubicin and cyclophosphamide for an additional 12 weeks before surgery.
- The phase 2 Adaptively Randomized I-SPY2 Trial 6 involved 4 cycles of pembrolizumab in combination with weekly paclitaxel followed by AC (doxorubicin and cyclophosphamide).
Treatment Regimens
- Based on these studies, the number of cycles of neoadjuvant pembrolizumab can vary, but common regimens involve:
- 4 cycles of pembrolizumab with paclitaxel, followed by 4 cycles of doxorubicin or epirubicin plus cyclophosphamide 2, 3, 6
- 8 cycles of pembrolizumab with a taxane and carboplatin, followed by doxorubicin and cyclophosphamide 5
- Completion of at least 8 cycles of pembrolizumab may be associated with improved pathological complete response rates 4