Pyrotinib data much better than T -DM1 and lapatinib
The PFS benefit (HR=0.374) surprised us despite previous qualitative commentsfrom Hengrui management. We believe it is highly likely Pyrotinib would be thegolden standard in 2L Herceptin relapsed HER2 positive BC in China. T o us,this is the second meaningful oncology clinical study from China ever , as trialdesign followed a reasonable treatment paradigm that is NOT full of Chinesecharacteristics. After data release at SABCS, we have higher conviction thatpyrotinib will be approved by CFDA based on P2 data.
We highlight our views in the following
Among trastuzumab relapsed patients, HR was 0.374 while mPFS hasnot been reached in PC arm, vs. 7.1m in LC arm. The baseline PFS dataseemed to be in line with historic data (6.4m from EMILIA, 7m from S Gori2016). The yet-to-be-reached mPFS should be more than 21m, accordingto the data release.
EMILIA study showed a PFS benefit of 9.6m for T -DM1 vs. 6.4m for LC,with a HR of 0.65. Our surprise came from a gap of 21m vs. 9.6m. If thesedata could be repeated in a P3 study, pyrotinib would become a goldenstandard in 2L BC.
Previous studies indicated that TTP (from 1L Herceptin treatment) couldbe a predictive marker for PFS/OS benefit second-line HER2 inhibitors.In this study, prior treatment of trastuzumab is associated with a longermPFS (7.1m vs. 5.6m for trastuzumab naive) for LC arms; data were alsoconsistent in PC arms. In our view, this should raise a serious questionfor Chinese regulators regarding the relevance of clinical data from thosestudies, specifically designed for Chinese patients today, who did notfollow NCCN treatment guidelines.
The additional questions include whether pyrotinib could be used in1L BC, or adjuvant setting, or used off-label in GC. For the first twoquestions, we believe further data are required. That being said, for GCsetting, despite the failure of T -DM1 (GATSBY study, 2L GC) and lapatinib(EGF110656, 1L GC), we gained reasonable confidence that pyrotinibmight work based on impressive P2 data.
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