This study is as exciting as it gets in terms of innovation and impact in a large population of metastatic breast cancer, low HER2 expressors. Rapid identification of such patients is of critical importance given the superiority to standard chemotherapy agents.
Among breast cancers without human epidermal growth factor receptor 2 (HER2) amplification, overexpression, or both, a large proportion express low levels of HER2 that may be targetable. Currently available HER2-directed therapies have been ineffective in patients with these “HER2-low” cancers.
We conducted a phase 3 trial involving patients with HER2-low metastatic breast cancer who had received one or two previous lines of chemotherapy. (Low expression of HER2 was defined as a score of 1+ on immunohistochemical [IHC] analysis or as an IHC score of 2+ and negative results on in situ hybridization.) Patients were randomly assigned in a 2:1 ratio to receive trastuzumab deruxtecan or the physician’s choice of chemotherapy. The primary end point was progression-free survival in the hormone receptor–positive cohort. The key secondary end points were progression-free survival among all patients and overall survival in the hormone receptor–positive cohort and among all patients.
Of 557 patients who underwent randomization, 494 (88.7%) had hormone receptor–positive disease and 63 (11.3%) had hormone receptor–negative disease. In the hormone receptor–positive cohort, the median progression-free survival was 10.1 months in the trastuzumab deruxtecan group and 5.4 months in the physician’s choice group (hazard ratio for disease progression or death, 0.51; P<0.001), and overall survival was 23.9 months and 17.5 months, respectively (hazard ratio for death, 0.64; P=0.003). Among all patients, the median progression-free survival was 9.9 months in the trastuzumab deruxtecan group and 5.1 months in the physician’s choice group (hazard ratio for disease progression or death, 0.50; P<0.001), and overall survival was 23.4 months and 16.8 months, respectively (hazard ratio for death, 0.64; P=0.001). Adverse events of grade 3 or higher occurred in 52.6% of the patients who received trastuzumab deruxtecan and 67.4% of those who received the physician’s choice of chemotherapy. Adjudicated, drug-related interstitial lung disease or pneumonitis occurred in 12.1% of the patients who received trastuzumab deruxtecan; 0.8% had grade 5 events.
In this trial involving patients with HER2-low metastatic breast cancer, trastuzumab deruxtecan resulted in significantly longer progression-free and overall survival than the physician’s choice of chemotherapy. (Funded by Daiichi Sankyo and AstraZeneca; DESTINY-Breast04 ClinicalTrials.gov number, NCT03734029. opens in new tab.)
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.
