57P - Response of gastric adenocarcinoma to neoadjuvant chemotherapy with respect to the presence or absence of HER2 overexpression: A prospective observational study

Background

Neoadjuvant chemotherapy (NACT) is a standard therapeutic approach for gastric cancers. However, response to NACTis heterogeneous and a notable subset of patients exhibit overexpression of the human epidermal growth factor receptor 2 (HER2). Despite this, the current neoadjuvant chemotherapy regimens do not typically incorporate HER2-targeted therapies. Furthermore, it is critical to evaluate the therapeutic efficacy of conventional neoadjuvant chemotherapy in this specific subgroup.

Methods

Present study was conducted over a period of one year on forty (40) patients with histologically confirmed Gastric or gastroesophageal junction adenocarcinoma; (cT2–4 or cN+) (AJCC 8.0 ) who received standard NACT with FLOT, XELOX or FOLFOX6 followed by surgery. The response to NACT was quantified by Tumour regression Grade, (Becker et al) The HER2 status was assessed by IHC and FISH. The pathological response was then matched against the Her 2 expression status in the gastrectomy specimens and the values were them statistically analysed to find significant correlation between overexpression of Her 2 receptors and response to NACT.

Results

Among 40 subjects, Her 2 over expression was seen in 9 (22.5%). None of the Her 2+ patients showed aTRG 1 response. Poor response to NACT (TRG3) was observed in 66.9% her2+ and 16.12% in her 2- group. (difference statistically significant with p value at .03). If we consider TRG 1 and 2 together as favourable and TRG 3 as unfavourable responses, 3/9 her2+ patients showed partially favourable response compared to 26/31 non her 2 over expressing patients; the difference being statistically significant at p =.0027. Both groups showed no significant difference in terms of Nodal Staging, Tumour Differentiation and LVI/PNI status.

Conclusions

Should it be determined that patients with HER2 overexpression consistently demonstrate suboptimal responses to standard neoadjuvant chemotherapy, the justification for subjecting these patients to the associated toxicities and potential risk of tumor progression needs or the option of adding Her2 targeted therapies in the Neoadjuvant setting is to be critically re-considered.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

The author.

Funding

Has not received any funding.

Disclosure

The author has declared no conflicts of interest.