Trastuzumab with FLOT Regimen for the Perioperative Treatment of Resectable HER2 + Advanced Gastric Cancer: A Retrospective Study

Perioperative Tailored Treatments for Gastric Cancer: Times Are Changing

Resectable gastric or gastroesophageal (G/GEJ) cancer is a heterogeneous disease with no defined molecularly based treatment strategy. Unfortunately, nearly half of patients experience disease recurrence despite standard treatments (neoadjuvant and/or adjuvant chemotherapy/chemoradiotherapy and surgery). In this review, we summarize the evidence of potential tailored approaches in perioperative treatment of G/GEJ cancer, with a special focus on patients with human epidermal growth factor receptor-2(HER2)-positive and microsatellite instability-high (MSI-H) tumors. In patients with resectable MSI-H G/GEJ adenocarcinoma, the ongoing INFINITY trial introduces the concept of non-operative management for patients with complete clinical-pathological-molecular response, and this could be a novel and potential practice changing strategy. Other pathways involving vascular endothelial growth factor receptor (VEGFR), fibroblast growth factor receptor (FGFR), claudin18 isoform 2 (CLDN18.2), and DNA damage repair proteins are also described, with limited evidence until now. Although tailored therapy appears to be a promising strategy for resectable G/GEJ cancer, there are several methodological issues to address: inadequate sample size for pivotal trials, underestimation of subgroup effects, and choice of primary endpoint (tumor-centered vs. patient-centered endpoints). A better optimization of G/GEJ cancer treatment allows maximizing patient outcomes. In the perioperative phase, although caution is mandatory, times are changing and tailored strategies could introduce new treatment concepts. Overall, MSI-H G/GEJ cancer patients possess the characteristics to be the subgroup that could receive the most benefit from a tailored approach.

HER2 in gastric adenocarcinoma: where do we stand today?

Aim: HER2 is a proto-oncogene expressed in 10-30% of gastric adenocarcinomas and is an ideal target for inhibition in malignancy with high recurrence and dismal survival rates. Materials & methods: A systematic search was conducted via PubMed, Google Scholar and the clinicaltrials.gov database to report the results of ongoing and past studies investigating HER2 inhibitors in gastric cancer. Results: Twenty-five studies were included; ToGA trial is the pivotal trial approving the use of trastuzumab in metastatic gastric cancer, followed by more studies investigating other HER2 inhibitors in this setting, as well as in local and locoregional malignancy. Conclusion: Anti-HER2 molecules are proving efficacy and safety in gastric cancer; the evidence is growing and association with other cancer agents is under investigation.

Effect of Additional Trastuzumab in Neoadjuvant and Adjuvant Treatment for Patients with Resectable HER2-Positive Gastric Cancer

BACKGROUND

Recent studies have reported a beneficial role of trastuzumab in neoadjuvant treatment (NAT) among resectable gastric cancer (GC) patients; however, the effect of adjuvant treatment (AT) combined with trastuzumab is understudied. We performed a retrospective cohort study to compare chemotherapies with or without trastuzumab among human epidermal growth factor receptor 2-positive (HER2 +) locally advanced GC patients in the AT and NAT settings, respectively.

METHODS

We enrolled 208 HER2 + resected GC patients who underwent perioperative/postoperative treatment in 2010-2019 in a single-centered hospital, including 135 AT patients and 73 NAT patients. We used inverse probability of treatment weighting (IPTW) to balance potential confounding factors between the treatment groups, and estimated the treatment effect of trastuzumab. Pathological and survival outcomes were evaluated.

RESULTS

The number of trastuzumab-exposed patients in the AT and NAT cohorts was 31 (23.0%) and 34 (46.6%), respectively. After IPTW adjustment, AT combined with trastuzumab showed a better overall survival (OS) over chemotherapy alone (p = 0.023). In IPTW-adjusted NAT analysis, trastuzumab-exposed patients had an improvement in tumor pathological regression and downstaging, with lower tumor regression grade scores (p = 0.002), ypTNM stages (p < 0.001), ypN stages (p = 0.035), and ypT stages (p < 0.001). Loss of HER2 positivity following trastuzumab treatment was observed in NAT patients; however, we did not observe any significant effect of trastuzumab on OS (p = 0.126).

CONCLUSIONS

Given the improvement in tumor regression and downstaging among NAT patients, and the OS benefit in AT patients, trastuzumab could be considered a promising treatment for locally advanced HER2 + GC patients. In particular, re-evaluation of HER2 status should be considered following NAT combined with trastuzumab.