Predictive value of serum HER2 ECD in patients with HER2-positive advanced gastric cancer treated with trastuzumab plus chemotherapy

Exploratory analysis of serum HER2 extracellular domain for HER2 positive gastric cancer treated with SOX plus trastuzumab

BACKGROUND

The aim of this study was to explore the clinical utility of serum HER2 extracellular domain (sHER2 ECD) using data from a clinical trial evaluating trastuzumab combined S-1 plus oxaliplatin (SOX) in HER2 positive gastric cancer.

METHODS

sHER2 ECD were prospectively measured at baseline and subsequent treatment courses. Based on each quantile point of baseline sHER2 ECD levels and its early changes, patients were divided into two groups and compared clinical outcomes.

RESULTS

43 patients were enrolled, and 17 patients (39.5%) were positive for baseline sHER2 ECD. Higher baseline sHER2 ECD levels tended to have lower hazard ratios (HRs). When divided into two groups by baseline sHER2 ECD of 19.1 ng/ml, median progression-free survival (PFS) and overall survival (OS) was longer in the higher group (mPFS: 16.8 vs 8.7 months, p = 0.359. mOS: 35.5 vs 20.6 months, p = 0.270), respectively. After initiation of treatment, sHER2 ECD significantly decreased up until the third cycle. Higher reduction rates of sHER2 ECD within 3 cycles also tended to have lower HRs. When divided into two groups by reduction rate of 42.5%, mPFS and mOS was longer in the higher reduced group (mPFS: 17.2 vs 8.7 months, p = 0.095. mOS: 65.0 vs 17.8 months, p = 0.047), respectively. Furthermore, higher reduction rates could surrogate higher objective response rates (ORR) (ORR: 90% vs 63.2% for 29.5%, p = 0.065. 100% vs 70% for 42.5%, p = 0.085), respectively.

CONCLUSIONS

Baseline sHER2 ECD levels and its early decline may be useful biomarkers for SOX plus trastuzumab efficacy in HER2 positive gastric cancer.

Inhibition of DPAGT1 suppresses HER2 shedding and trastuzumab resistance in human breast cancer

Human epidermal growth factor receptor 2-targeted (HER2-targeted) therapy is the mainstay of treatment for HER2+ breast cancer. However, the proteolytic cleavage of HER2, or HER2 shedding, induces the release of the target epitope at the ectodomain (ECD) and the generation of a constitutively active intracellular fragment (p95HER2), impeding the effectiveness of anti-HER2 therapy. Therefore, identifying key regulators in HER2 shedding might provide promising targetable vulnerabilities against resistance. In the current study, we found that upregulation of dolichyl-phosphate N-acetylglucosaminyltransferase (DPAGT1) sustained high-level HER2 shedding to confer trastuzumab resistance, which was associated with poor clinical outcomes. Upon trastuzumab treatment, the membrane-bound DPAGT1 protein was endocytosed via the caveolae pathway and retrogradely transported to the ER, where DPAGT1 induced N-glycosylation of the sheddase - ADAM metallopeptidase domain 10 (ADAM10) - to ensure its expression, maturation, and activation. N-glycosylation of ADAM10 at N267 protected itself from ER-associated protein degradation and was essential for DPAGT1-mediated HER2 shedding and trastuzumab resistance. Importantly, inhibition of DPAGT1 with tunicamycin acted synergistically with trastuzumab treatment to block HER2 signaling and reverse resistance. These findings reveal a prominent mechanism for HER2 shedding and suggest that targeting DPAGT1 might be a promising strategy against trastuzumab-resistant breast cancer.

Multicenter phase II study of trastuzumab with S-1 plus oxaliplatin for chemotherapy-naïve, HER2-positive advanced gastric cancer

BACKGROUND

Trastuzumab with cisplatin and fluoropyrimidines improves overall survival (OS) in patients with HER2-positive advanced gastric cancer (AGC). S-1 plus oxaliplatin (SOX) is one of the standard regimens for HER2-negative AGC in Japan. However, few studies have evaluated trastuzumab combined with SOX in patients with HER2-positive AGC.

METHODS

This was a multicenter, phase II study conducted at 10 institutions in Japan. Patients with HER2-positive AGC received S-1 twice a day on days 1-14 and oxaliplatin and trastuzumab on day 1 of a 21-day cycle. The primary endpoint was the confirmed overall response rate (ORR), and the secondary endpoints were OS, progression-free survival (PFS), and safety. The sample size was 75 to have 90% power with an alpha error of 0.1 (one-sided), expecting an ORR of 65% and threshold of 50%.

RESULTS

From June 2015 to January 2018, 75 patients were enrolled. The ORR was 70.7% [95% confidence interval (CI) 59.0-80.6]. The median OS and PFS were estimated as 18.1 months (95% CI 15.6-26.5) and 8.8 months (95% CI 7.4-12.2), respectively. The major grade 3 or 4 adverse events were sensory neuropathy (16.0%) and neutropenia (10.7%).

CONCLUSIONS

Trastuzumab with SOX had promising activity with well-tolerated toxicities for patients with HER2-positive AGC.

CLINICAL TRIAL REGISTRATION

UMIN000017602.

Clinical significance of intratumoral HER2 heterogeneity on trastuzumab efficacy using endoscopic biopsy specimens in patients with advanced HER2 positive gastric cancer

BACKGROUND

We recently reported the clinical significance of intratumoral HER2 heterogeneity on trastuzumab efficacy using surgical specimens; patients with homogeneously HER2 positive gastric cancer benefitted more from trastuzumab. However, the majority of patients are diagnosed by endoscopic biopsy, and surgical specimens are not available in these patients. The aim of this study is to verify clinical significance of HER2 heterogeneity on trastuzumab efficacy using biopsy specimens.

METHODS

Eighty-seven patients, who received trastuzumab-based chemotherapy and whose endoscopic biopsy specimens were available for HER2 assessment, were consecutively enrolled. When all tumor cells in all biopsy specimens overexpressed HER2 protein, it was defined as homogeneously HER2 (homo-HER2) positive group, and the others were defined as heterogeneously HER2 (hetero-HER2) positive group. Progression-free survival (PFS), overall survival (OS) and objective response rate (ORR) were evaluated.

RESULTS

Thirty-four patients (39%) were diagnosed as the homo-HER2 group and 53 patients (61%) were the hetero-HER2 group. After the median follow-up period of 17.8 months, the median PFS and OS were 7.6 and 17.8 months, respectively. Significant survival differences were shown between the two groups; the homo-HER2 group showed significantly longer PFS (10.8 vs. 6.1 months, HR 0.469 95% CI 0.29-0.77, p = 0.003) and OS (29.3 vs. 14.4 months, HR 0.352 95% CI 0.20-0.61, p < 0.001). ORR was 68.6% in this cohort. Higher response rate (85.2% vs 58.1%, p = 0.020) and deeper response (- 49.0% vs - 40.0%, p = 0.018) were also found in the homo-HER2 group.

CONCLUSIONS

Similar to surgical specimens, we verified clinical significance of HER2 heterogeneity on trastuzumab efficacy using endoscopic biopsy specimens.

Five-weekly S-1 plus cisplatin therapy combined with trastuzumab therapy in HER2-positive gastric cancer: a phase II trial and biomarker study (WJOG7212G)

BACKGROUND

Five-weekly S-1 plus cisplatin (SP) therapy is the standard care for advanced gastric or esophagogastric junction cancer (GC/EGJC) in East Asia. However, its efficacy and safety when combined with trastuzumab therapy for human epidermal growth factor receptor 2 (HER2)-positive advanced GC/EGJC remains unclear.

METHODS

Patients received 5-weekly SP therapy (S-1 at 40-60 mg twice daily for 21 days plus cisplatin at 60 mg/m² on day 8, every 5 weeks) plus trastuzumab therapy (first dose of 8 mg/kg, then 6 mg/kg every 3 weeks). The primary end point was the response rate, and the secondary end points included progression-free survival, overall survival, safety, and serum biomarker levels.

RESULTS

Forty-four patients were enrolled. The response rate, progression-free survival, and overall survival were 61% (95% confidence interval 46-76%), 5.9 months, and 16.5 months respectively. The commonest grade 3 or grade 4 adverse events were neutropenia (30%) and anorexia (25%). A significantly higher response rate (92% vs 43%; P = 0.008) and longer progression-free survival (median 14.5 months vs 4.2 months; P = 0.028) were observed in patients with high (n = 14) compared with low (n = 17) pretreatment serum neuregulin 1 levels.

CONCLUSIONS

Five-weekly SP therapy combined with trastuzumab therapy showed a good antitumor response and acceptable toxicity in HER2-positive advanced GC/EGJC. Serum neuregulin 1 might be associated with the efficacy of this treatment regimen.

Depth of response predicts the clinical outcome of advanced HER2-positive gastric cancer to trastuzumab-based first-line chemotherapy

PURPOSE

Accumulating evidence suggests that response-related parameters such as depth of response (DpR) might be associated with survival in colorectal cancer, which has not been shown in gastric cancer. This study aimed to evaluate whether DpR was associated with clinical outcomes in HER2-positive AGC patients treated with trastuzumab-based chemotherapy.

METHODS

Fifty-seven HER2-positive AGC patients who were treated with trastuzumab in combination with fluoropyrimidines plus cisplatin therapy as first-line treatment were retrospectively enrolled. DpR was defined as the percent maximal tumor shrinkage of target lesions observed at the lowest point compared with baseline. The cutoff DpR level to discriminate better survival was based on receiver-operating characteristic curve analysis. Association of DpR with progression-free survival (PFS) and overall survival (OS) was assessed using the multivariable Cox proportional hazards model.

RESULTS

Median DpR level was 56.8% (range -37.9 to 100%). In multivariate models adjusted for relevant variables, DpR, as a dichotomized variable with a cutoff level of 50% and a continuous variable, was significantly associated with PFS (hazard ratio [HR] 0.39 and 0.97; 95% confidence interval [CI] 0.22-0.68 and 0.96-0.98) and OS (HR 0.38 and 0.98; 95% CI 0.21-0.70 and 0.97-0.99). Clinically meaningful differences in PFS (median, 9.8 vs. 4.1 months; p < 0.001) and OS (median, 24.7 vs. 12.8 months; p < 0.001) were observed between the high DpR (≥50%) and the low DpR groups (<50%).

CONCLUSIONS

Higher DpR predicted favorable outcomes following trastuzumab-based chemotherapy in HER2-positive AGC patients.

Predictive biomarkers for targeted and cytotoxic agents in gastric cancer for personalized medicine

Gastric cancer (GC) is the fourth most common cancer and the second leading cause of cancer. The treatment of GC remains challenging as the outcomes achieved with surgery alone or adjuvant or neoadjuvant chemotherapy and radiotherapy are relatively poor. New treatment strategies are emerging and are being tested in solid tumors including GC. Over the past few years, the treatment of metastatic colorectal cancer (CRC) has made great advances, but strategies to manage GC have improved little. Multiple drug resistance is common in GC chemotherapy and targeted therapy; some patients appear to receive treatment that is suboptimal or even inefficacious. Unfortunately, there are few validated predictive biomarkers to guide the tailored treatment of GC. ToGA and AVAGAST are two phase III trials that tested the efficacy and safety of targeted agents in advanced gastric cancer (AGC), and results clearly indicated that patients need to be selected and that targeted agents are the best hope for better results. This review aims to provide an overview of potential predictive biomarkers for cytotoxic and targeted agents in GC.

Associations between serum CA724 and HER2 overexpression among stage II-III resectable gastric cancer patients: an observational study

OBJECTIVES

Associations between serum tumor biomarkers and human epidermal growth factor receptor 2 (HER2) overexpression among locally advanced gastric cancer patients were yet to be determined and therefore warranted investigation.

RESULTS

A total of 318 patients were analyzed. The odds ratios of CA724 were 4.79 (95% CI 1.55-14.79) and 6.29 (1.40-28.19) in comparing the HER2 (2+/3+) and HER2 (3+) with the negative group, respectively (p < 0.05). A combination of the four biomarkers yielded slightly but not significantly greater areas under the curve (AUC = 0.83; 0.71-0.94) than that of serum CA724 alone (0.80; 0.68-0.91); however, an index generated from the combination had better diagnostic performance with 85.7% sensitivity, 80.4% specificity and 97.8% negative predictive value to predict the strong overexpression of HER2 (3+). CA199, CEA or CA125 alone was not associated with HER2 overexpression. Leave-one-out cross-validation found a consistent association between serum CA724 and HER2 (2+/3+) overexpression.

METHODS

Patients undergoing radical gastrectomy from 8/2012 to 12/2013 and with pathological stage II-III gastric cancer were retrospectively analyzed. HER2 expression of the surgical samples was estimated using immunohistochemistry; serum CA724, CA199, CEA and CA125 were preoperatively tested. Internal validation was performed using the leave-one-out approach.

CONCLUSIONS

Serum CA724 is significantly associated with the overexpression of HER2 among locally advanced gastric cancer patients. The combination of CA724, CA199, CEA and CA125 is better than serum CA724 alone in predicting HER2 overexpression. External validation and further investigation of the biological mechanisms of these associations are required.