Prospective biomarker analysis of the randomized CHER-LOB study evaluating the dual anti-HER2 treatment with chemotherapy plus trastuzumab and lapatinib as neoadjuvant therapy for HER2-positive breast cancer [expression]
The CHER-LOB randomized phase II study showed that the combination of lapatinib and trastuzumab plus chemotherapy increases the pathologic complete remission (pCR) rate as compared to chemotherapy plus either trastuzumab or lapatinib. An extensive biomarker programme was prospectively planned to identify potential predictors of sensitivity to different treatments and evaluate treatment effect on tumor biomarkers. A mutation in PIK3CA exon 20 or 9 was documented in 20% of the cases. Overall, the pCR rates were similar in PIK3CA wild type and PIK3CA mutated patients (33.3% vs 22.7%; p=0.323). However, for patients receiving trastuzumab plus lapatinib, the probability of pCR was higher in PIK3CA wild type tumors (48.4% vs 12.5%; p=0.06). Ki67, pAKT and apoptosis measured on the residual disease were significantly reduced from baseline. The degree of Ki67 inhibition was significantly higher in patients receiving the dual anti-HER2 blockade. In conclusion, PIK3CA mutations seem to identify patients less likely to benefit from dual anti-HER2 inhibition. p95-HER2 and markers of PI3K pathway deregulation are not confirmed as markers of different sensitivity to trastuzumab or lapatinib.
Overall design
121 HER2-positive breast cancer patients were randomly assigned to neoadjuvant chemotherapy plus either trastuzumab, lapatinib or both trastuzumab and lapatinib. Pre-treatment, fresh-frozen tissue samples were collected for genomic analyses. 88 samples passed quality control for RNA and were profiled with Affymetrix technology using the HG-U133 Plus 2.0 GeneChip array.
Prospective biomarker analysis of the randomized CHER-LOB study evaluating the dual anti-HER2 treatment with chemotherapy plus trastuzumab and lapatinib as neoadjuvant therapy for HER2-positive breast cancer
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