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Best abstracts selected from submissions 4 (ID 4)
- Event: ACLC 2018
- Type: Oral Session
- Presentations: 1
- Coordinates: 11/09/2018, 10:50 - 11:30, Crystal Ballroom
OA07 - Clinical Characterization Of ERBB2 Exon 20 Insertions and Heterogeneity of Outcomes to Afatinib in Chinese Lung Cancers (ID 188)
10:50 - 11:30 | Author(s): B. Li
Human epidermal growth factor 2 (HER2, ERBB2) gene alterations have been identified as oncogenic drivers in 2-5% of lung cancers. ERBB2 In-frame insertions in exon 20 (20ins) lead to constitutive activation of receptor and downstream pathways. However, response heterogeneity of different exon 20 insertions to ERBB2 inhibitor afatinib exists. In vitro and structural modeling results suggested that Glycine778 may facilitate inhibitor binding to ERBB2. In this study, our aim was to improve our understanding of clinical characteristics in ERBB2-mutated Chinese lung cancer and investigate the clinical outcomes of specific ERBB2 exon 20 insertions in response to afatinib.
We reviewed 7520 lung cancer patients whose tissue or plasma biopsies were sequenced in a CLIA-certified sequencing laboratory between 2015 to 2018. Clinical records of 19 patients (18 adenocarcinomas and 1 squamous cell carcinoma) with several different ERBB2 20ins after afatinib treatment were collected for clinical outcomes evaluation.
ERBB2 20ins were identified in 2.27% (171/7,520) in this Chinese lung cancer cohort. It occurred with a high proportion in females with adenocarcinoma histology. 11.7% (20/171) ERBB2 20ins-positive patients harbored concomitant ERBB2 amplification. Y772_A775dup (119/171, 69.6%) was the most frequently occurred 20ins subtype, followed by G778_P780dup (18/171, 10.5%). For the 19 patients treated with afatinib, they had a median PFS of 4.5 months and median OS of 11.5 months. The overall response rate in this cohort was 15.8% (3/19) and disease control rate was 68.4% (13/19). Next, we interrogated the clinical outcomes of specific 20ins subtype responding to afatinib. We found that patients harboring G778_P780dup (G778) achieved longer median PFS (10 vs 3.3 months, p=0.32) and median OS (19.7 vs 7 months, p=0.16) than non-G778 patients, consisting with in vitro results. Although statistical significance was not achieved due to limited number of G778_P780dup patients, this result warranted further investigation into this phenomenon. Moreover, to the best of our knowledge, we identified the first case of a lung squamous cell carcinoma patient harboring ERBB2 20ins from this cohort. He displayed favorable response to afatinib and achieved partial response with significant tumor shrinkage.
We interrogated the characteristics of ERBB2 exon 20 insertions in a large cohort from single ethnicity. It demonstrated the response heterogeneity to afatinib among different ERBB2 exon 20 insertion subtypes. It highlighted the importance to correlate drug efficacy with specific ERBB2 exon 20 insertion variants in clinical application.
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