Findings from the PACE study show that the addition of Palbociclib to Fulvestrant was not better than Fulvestrant alone, and the addition of Avelumab to Fulvestrant improved and nearly doubled the PFS. This is compelling and should be studied further for our patients with HR+ HER2- MBC.
Cyclin-dependent kinase (CDK) 4/6 inhibitors (CDK4/6is) are an important component of treatment for hormone receptor–positive/human epidermal growth factor receptor 2–negative (HER2–) metastatic breast cancer (MBC), but it is not known if patients might derive benefit from continuation of CDK4/6i with endocrine therapy beyond initial tumor progression or if the addition of checkpoint inhibitor therapy has value in this setting.
The randomized multicenter phase II PACE trial enrolled patients with hormone receptor–positive/HER2– MBC whose disease had progressed on previous CDK4/6i and aromatase inhibitor (AI) therapy. Patients were randomly assigned 1:2:1 to receive fulvestrant (F), fulvestrant plus palbociclib (F + P), or fulvestrant plus palbociclib and avelumab (F + P + A). The primary end point was investigator-assessed progression-free survival (PFS) in patients treated with F versus F + P.
Overall, 220 patients were randomly assigned between September 2017 and February 2022. The median age was 57 years (range, 25-83 years). Most patients were postmenopausal (80.9%), and 40% were originally diagnosed with de novo MBC. Palbociclib was the most common previous CDK4/6i (90.9%). The median PFS was 4.8 months on F and 4.6 months on F + P (hazard ratio [HR], 1.11 [90% CI, 0.79 to 1.55]; P = .62). The median PFS on F + P + A was 8.1 months (HR v F, 0.75 [90% CI, 0.50 to 1.12]; P = .23). The difference in PFS with F + P and F + P + A versus F was greater among patients with baseline ESR1 and PIK3CA alterations.
The addition of palbociclib to fulvestrant did not improve PFS versus fulvestrant alone among patients with hormone receptor–positive/HER2– MBC whose disease had progressed on a previous CDK4/6i plus AI. The increased PFS seen with the addition of avelumab warrants further investigation in this patient population.
MammaPrint did not predict distant recurrence, but it did predict patients who may benefit from extended hormonal therapy. We do have breast index, so now we have options. Breast index can predict the possibility of recurrence though by helping to determine the level of risk.
This study confirms what we saw in initial reports showing the addition of pembro increasing the rate of ypathological complete response (ypCR’s) in the neoadjuvant setting for triple-negative breast cancer (TNBC). New data shows a 5% improvement (87 vs 82%) in overall survival (OS) with the quadruplet. Higher gains but at higher cost of toxicity. The fact that adjuvant intraosseous (IO) does not seem to improve outcomes, but neoadjuvant chemo+IO does show intact tumor-immune interactions to create maximum treatment effectiveness is most likely real. Of note, this seems mostly independent of programmed death-ligand 1 (PDL1) status.
Adding Inavolisib to CKD4/6 inhibitor and AI improved progression-free survival (almost doubled 15 vs 7m) but toxicity was higher still in the single digits (hyperglycemia, diarrhea, stomatitis… all less than 6% G3/4).
Well done study showing a 20% decrease in recurrence risk when using dose dense therapy [EC]/D compared to conventional dose [FEC]/D. Sometimes it is worth it to push.
Myth busted. In aggressive breast cancer, no need to start chemotherapy now, ET and CKD4/6 inhibitors are better tolerated with significant progression-free survival (PFS) benefit and same response rate.
FCS Hematology Oncology Review creates a platform for our physician network to observe the most recent articles and studies available in the oncology and hematology world. By sharing these articles we are building our wealth of knowledge of new observations and treatments as they come available.
