Pertuzumab plus trastuzumab and chemotherapy for Japanese patients with HER2-positive metastatic gastric or gastroesophageal junction cancer: a subgroup analysis of the JACOB trial

Preparation of Radiolabeled Zolbetuximab Targeting CLDN18.2 and Its Preliminary Evaluation for Potential Clinical Applications

Claudin18.2 (CLDN18.2), due to its high expression in various gastric cancer tissues, is considered an optimal target for antitumor drug molecules. In this study, we obtained the labeled compounds of [125I]I-zolbetuximab using the Iodogen method. Under the optimum labeling conditions, the molar activity of [125I]I-zolbetuximab was 1.75 × 102 GBq/μmol, and the labeling efficiency was more than 99%. The labeled compounds exhibited excellent in vitro stability in both phosphate buffer saline (PBS, pH = 7.4) and fetal bovine serum systems (FBS) (radiochemical purity >90% at 72 h). The uptake percentage of [125I]I-zolbetuximab in MKN45-CLDN18.2 cells is 24.69 ± 0.84% after 6 h. The saturation binding assay and specificity assay further demonstrated the high specificity of [125I]I-zolbetuximab for CLDN18.2. The long retention at the tumor site and rapid metabolic clearance at other organ sites of [125I]I-zolbetuximab were observed in small-animal SPECT-CT imaging. The same trend was also observed in the biodistribution study. Due to the excellent targeting ability of zolbetuximab for CLDN18.2, [125I]I-zolbetuximab exhibits strong specific binding and retention with cells and tumors highly expressing CLDN18.2. However, the balance between mAb's longer cycle time in vivo and targeting binding and retention ability should be intensively considered for using this kind of radiopharmaceutical in the diagnosis and treatment of CLDN18.2-positive gastric cancer.

HER-2 positive gastric cancer: Current targeted treatments

Gastric cancer (GC) is highly metastatic and characterized by HER2 amplification. Aberrant HER2 expression drives metastasis, therapy resistance, and tumor recurrence. HER2 amplification contributes to drug resistance by upregulating DNA repair enzymes and drug afflux proteins, reducing drug efficacy. HER2 modulates transcription factors critical for cancer stem cell properties, further impacting drug resistance. HER2 activity is influenced by HER-family ligands, promoting oncogenic signaling. These features point to HER2 as a targetable driver in GC. This review outlines recent advances in HER2-mediated mechanisms and their upstream and downstream signaling pathways in GC. Additionally, it discusses preclinical research investigation that comprehends trastuzumab-sensitizing phytochemicals, chemotherapeutics, and nanoparticles as adjunct therapies. These developments hold promise for improving outcomes and enhancing the management of HER2-positive GC.

Survival after Trastuzumab Therapy in Patients with Locally Advanced or Metastatic HER2-Positive Gastric or Gastroesophageal Junction Cancer: A Meta-Analysis of Randomized Controlled Trials

Background

In the Trastuzumab for Gastric Cancer study, it was found that trastuzumab combined with doublet chemotherapy (fluoropyrimidine and platinum) was the gold-standard treatment for gastroesophageal adenocarcinoma (GEA) that was locally advanced, unresectable, or metastatic (HER2+).

Materials and Methods

We performed a meta-analysis of randomized phase II/III studies testing trastuzumab in combination or alone.

Results

This meta-analysis's findings involved 2048 patients in total. The treatment arm and hormone receptor status were used to stratify the combined HR. Overall, the PFS (Random model) HR [0.80] and 95% confidence intervals (CI) [0.68-0.95] were significantly higher for regimens containing trastuzumab, fluoropyrimidine, and platinum compared to regimens containing fluoropyrimidine and platinum.

Conclusions

The results of this meta-analysis provide additional support for trastuzumab's use in treating HER2-positive GEA, particularly in cases where the disease lacks a HER2+ receptor.

Antigen-Specific T Cell Immunotherapy Targeting Claudin18.2 in Gastric Cancer

Simple Summary

Claudin18.2 is expressed in the primary and metastatic gastric cancer, making Claudin18.2 a suitable target for antigen-specific T cell immunotherapy. In this study, we first identified 12 Claudin18.2 peptides that had immunogenicity, and found that T cells stimulated by Claudin18.2 peptides had stronger anti-tumor activity and higher effective cytokine-secreting ability in vitro. We also found that Claudin18.2 peptide reactivity was associated with older age and higher Claudin18.2 expression, which helped to screen appropriate patients. The value of Claudin18.2 in the T cell-based GC immunotherapy has been affirmed in this study.

Abstract

T cell-based immunotherapy has led to many breakthroughs in the treatment of solid tumors. In this study, we found that membrane protein Claudin18.2 was a promising antigen in T cell-based immunotherapy for gastric cancer (GC). Firstly, we identified five HLA-A*0201- and seven HLA-A*1101-restricted T cell epitopes of Claudin18.2. Peripheral blood mononuclear cells (PBMCs) stimulated by Claudin18.2 peptides showed progressive anti-tumor ability and higher effective cytokine secretion than unstimulated PBMCs in vitro. In total, 81.8% of GC patients were Claudin18.2-positive by immunohistochemical (IHC) detection, and a positive correlation between Claudin18.2 expression and peptide reactivity (p = 0.002) was found. Clinicopathological features analyses demonstrated that Claudin18.2 expression did not correlate with gender, age, stage or Lauren classification. Survival analysis showed that a longer median progression-free survival (mPFS) was not related to peptide reactivity (p = 0.997), but related to a lower Claudin18.2 expression level (p = 0.047). These findings establish a foundation for the clinical application of Claudin18.2 targeted T cell-based immunotherapy in GC.

Validity of the Cancer and Aging Research Group Predictive Tool in Older Japanese Patients

Background: This study aimed to evaluate the usefulness of the Cancer and Aging Research Group (CARG) predictive tool in older Japanese patients with cancer. Methods: Patients aged 65 years or older with solid tumors treated with new anticancer regimens in Kakogawa Central City Hospital between April 2016 and March 2019 were included. Grade 3 or higher risks of developing chemotherapy-related adverse events (CRAEs) were calculated using the tool (low-, intermediate-, or high-risk scores). The association between grade 3−5 CRAE incidence during the first course of each regimen and the calculated risk or the patient characteristics was evaluated. The difference in the incidences of CRAEs between the groups was evaluated by Fisher’s exact test. Results: This study examined 76 patients (mean age: 71 (65−82) years). The incidence of grade 3−5 CRAE was 38%, 55%, and 76% in patients classified as low, medium, and high CARG risk scores (p = 0.035), and the incidence of severe non-hematological toxicities was 4%, 31%, and 52% (p < 0.01), respectively. Eastern Cooperative Oncology Group performance status and age were not associated with chemotherapy toxicity. Conclusions: The CARG predictive tool was valid, suggesting its usefulness in optimizing chemotherapy outcomes in older patients with cancer.

Safety and efficacy of HER2 blockade by trastuzumab-based chemotherapy-containing combination strategies in HER2+ gastroesophageal adenocarcinoma

Since completion of the Trastuzumab for Gastric Cancer study, trastuzumab with doublet chemotherapy (a fluoropyrimidine and a platinum) has been the gold-standard first-line therapy for patients with locally advanced unresectable or metastatic human epidermal growth factor receptor 2-positive (HER2+) gastroesophageal adenocarcinoma (GEA). The safety and efficacy of 23 studies of first-line trastuzumab plus doublet chemotherapy, without checkpoint inhibitors (n = 19) or with checkpoint inhibitors (n = 4), conducted in patients with locally advanced unresectable or metastatic HER2+ GEA, including phase II/III, prospective, and retrospective observational studies, were summarized. In studies without checkpoint inhibitors, the median duration of trastuzumab treatment ranged from 19.5 to 39.0 weeks and from 15.3 to 30.0 weeks for chemotherapy. In studies with checkpoint inhibitors, the median duration of pembrolizumab/trastuzumab/chemotherapy was 30 weeks, and 18 weeks for chemotherapy. In studies without checkpoint inhibitors, treatment-emergent adverse events (TEAEs) of grade ≥3 ranged from 32% to 84%. Serious adverse events (SAEs) ranged from 15% to 39%. Adverse events resulting in discontinuation ranged from 0% to 30%. Treatment-related deaths occurred in 0%-9% of patients. In studies with checkpoint inhibitors, TEAEs of grade ≥3 were 57%. SAEs ranged from 31% to 38%. Adverse events resulting in discontinuation ranged from 5% to 24%. Treatment-related deaths occurred in 0%-3% of patients. In studies without checkpoint inhibitors, objective response rate (ORR) ranged from 39% to 82%, median progression-free survival (PFS) from 5.7 to 11.6 months, and median overall survival (OS) from 11.2 to 27.6 months. In studies with checkpoint inhibitors, ORR ranged from 39% to 86%, median PFS from 8.0 to 13.0 months, and median OS from 19.3 to 27.3 months. This review provides a historical benchmark on safety and efficacy of available first-line chemotherapy-based standard of care for patients with locally advanced unresectable or metastatic HER2+ GEA.

Development of a Novel Anti-HER2 Monoclonal Antibody H2Mab-181 for Gastric Cancer

Human epidermal growth factor receptor 2 (HER2) is a type I transmembrane 185 kDa protein. HER2 is expressed in a variety of normal tissue types and cancer cells. HER2 is associated with cell proliferation, differentiation, and migration. The overexpression of HER2 has been observed in a number of cancers, including breast and gastric cancers. Gastric cancer is one of the most common cancers worldwide, with an annual case rate of ∼1 million people diagnosed with the disease. Trastuzumab is a humanized anti-HER2 monoclonal antibody (mAb) that has been utilized in gastric cancer therapy. In this study, we have developed a novel anti-HER2 mAb, H₂Mab-181 (IgG₁, kappa), through the immunization of mice with a purified recombinant extracellular domain of HER2. H₂Mab-181 can specifically and sensitively detect HER2 in both flow cytometry and Western blot applications in gastric cancer cell lines and can also be utilized in immunohistochemical analyses of gastric cancer tissues. Together, H₂Mab-181 could be useful for the diagnosis and therapy in gastric cancers.

Synergistic antitumor effect of the anti-ErbB2 antibodies trastuzumab and H2-18 on trastuzumab-resistant gastric cancer cells

Trastuzumab resistance is a severe problem in the treatment of ErbB2-amplified cancer. Although trastuzumab plus pertuzumab is able to partly overcome trastuzumab resistance in ErbB2-overexpressing cancer, its antitumor efficacy remains limited. The present study investigated the antitumor activity of the combination of trastuzumab with H2-18, which is an antibody targetinsg ErbB2 domain I. Cell proliferation and inhibition experiments indicated that H2-18 and trastuzumab synergistically inhibited the proliferation of both the trastuzumab-sensitive gastric cancer cell line, NCI-N87 and the trastuzumab-resistant gastric cancer cell line, NCI-N87-TraRT. Furthermore, H2-18 plus trastuzumab inhibited the growth of NCI-N87-TraRT cells more effectively than trastuzumab plus pertuzumab, both in vitro and in vivo. Compared with trastuzumab plus pertuzumab, H2-18 plus trastuzumab had a potent ability to inhibit NCI-N87-TraRT cells to form colonies. Notably, H2-18 plus trastuzumab was more effective in inducing cell death than trastuzumab plus pertuzumab. The in vivo studies demonstrated that H2-18 plus trastuzumab effectively inhibited the growth of both NCI-N87 and NCI-N87-TraRT xenograft tumors. Further experiments revealed that in NCI-N87-TraRT cells, H2-18 plus trastuzumab was comparable to trastuzumab plus pertuzumab in the inhibition of phosphorylated (p-)HER3, p-AKT and p-ERK. However, compared with trastuzumab plus pertuzumab, H2-18 plus trastuzumab effectively activated ROS production and the phosphorylation of JNK and c-jun in NCI-N87-TraRT cells. Therefore, the superior antitumor efficacy of H2-18 plus trastuzumab over trastuzumab plus pertuzumab may be mainly attributable to the potent cell death-inducing activity. In addition, the in vitro and in vivo antitumor effect of the combination of H2-18, trastuzumab and pertuzumab were further investigated. The results revealed that H2-18 plus trastuzumab plus pertuzumab exhibited a maximal antitumor effect among all the anti-ErbB2 monoclonal antibody combinations tested. In summary, H2-18 plus trastuzumab may have potential as an effective strategy to overcome the resistance to trastuzumab in ErbB2-amplified gastric cancer cell lines.

Mechanisms of Pharmaceutical Therapy and Drug Resistance in Esophageal Cancer

Pharmaceutical therapies are essential for esophageal cancer (EC). For the advanced EC, the neoadjuvant therapy regimen, including chemotherapy plus radiotherapy and/or immunotherapy, is effective to achieve clinical benefit, even pathological complete response. For the unresectable, recurrent, and metastatic EC, the pharmaceutical therapy is the limited effective regimen to alleviate the disease and prolong the progression-free survival and overall survival. In this review, we focus on the pharmaceutical applications in EC treatment including cytotoxic agents, molecular targeted antibodies, and immune checkpoint inhibitors (ICIs). The chemotherapy regimen is based on cytotoxic agents such as platinum-based complexes, fluorinated pyrimidines and taxenes. Although the cytotoxic agents have been developed in past decades, the standard chemotherapy regimen is still the cisplatin and 5-FU or paclitaxel because the derived drugs have no significant advantages of overcoming the shortcomings of side effects and drug resistance. The targeted molecular therapy is an essential supplement for chemotherapy; however, there are only a few targeted therapies available in clinical practice. Trastuzumab and ramucirumab are the only two molecular therapy drugs which are approved by the US Food and Drug Administration to treat advanced and/or metastatic EC. Although the targeted therapy usually achieves effective benefits in the early stage therapy of EC, the patients will always develop drug resistance during treatment. ICIs have had a significant impact on routine clinical practice in cancer treatment. The anti-programmed cell death-1 monoclonal antibodies pembrolizumab and nivolumab, as the ICIs, are recommended for advanced EC by several clinical trials. However, the significant issues of pharmaceutical treatment are still the dose-limiting side effects and primary or secondary drug resistance. These defects of pharmaceutical therapy restrain the clinical application and diminish the effectiveness of treatment.