Emerging Therapeutic Targets and Future Directions in Advanced Gastric Cancer: A Comprehensive Review

Metastatic gastric cancer (GC) still represents a critical clinical challenge, with limited treatment options and a poor prognosis. Most patients are diagnosed at advanced stages, limiting the chances of surgery and cure. The identification of molecular targets and the possibility of combining immune checkpoint inhibitors with chemotherapy have recently reshaped the therapeutic landscape of metastatic gastric cancer. The new classification of gastric cancer, mainly based on immunologic and molecular criteria such as programmed cell death 1 (PD-1), microsatellite instability (MSI), and human epidermal growth factor receptor 2 (HER2), has made it possible to identify and differentiate patients who may benefit from immunotherapy, targeted therapy, or chemotherapy alone. All relevant and available molecular and immunological targets in clinical practice for the systemic treatment of this disease are presented. Particular attention is given to possible future approaches, including circulating tumor DNA (ctDNA) for therapeutic monitoring, new targeting agents against molecular pathways such as fibroblast growth factor receptor (FGFR) and MET, chimeric antigen receptor (CAR)-T cells, and cancer vaccines. This review aims to provide a comprehensive understanding of current targets in advanced gastric cancer and to offer valuable insights into future directions of research and clinical practice in this challenging disease.

A Clinical Viewpoint on the Use of Targeted Therapy in Advanced Gastric Cancer

The development of therapies for advanced gastric cancer (GC) has made significant progress over the past few years. The identification of new molecules and molecular targets is expanding our understanding of the disease's intricate nature. The end of the classical oncology era, which relied on well-studied chemotherapeutic agents, is giving rise to novel and unexplored challenges, which will cause a significant transformation of the current oncological knowledge in the next few years. The integration of established clinically effective regimens in additional studies will be crucial in managing these innovative aspects of GC. This study aims to present an in-depth and comprehensive review of the clinical advancements in targeted therapy and immunotherapy for advanced GC.

Ramucirumab plus irinotecan / leucovorin / 5-FU versus ramucirumab plus paclitaxel in patients with advanced or metastatic adenocarcinoma of the stomach or gastroesophageal junction, who failed one prior line of palliative chemotherapy: the phase II/III RAMIRIS study (AIO-STO-0415)

BACKGROUND

Paclitaxel in combination with ramucirumab is the standard of care second-line therapy in gastro-esophageal adenocarcinoma (GEA). As the number of taxane pretreated patients in the perioperative or first-line setting is increasing, it is unknown whether these patients benefit from re-applying a taxane in using the combination of paclitaxel and ramucirumab. Furthermore, the rates of neurotoxicity with first-line FOLFOX or FLOT range from 30%-70%, making second-line taxane-containing therapy less suitable to a meaningful portion of patients. This patient group is likely to benefit from a taxane-free second-line chemotherapy regimen, such as FOLFIRI and ramucirumab (FOLFIRI-Ram). Therefore, the RAMIRIS phase III trial evaluates the effects of the regimen of FOLFIRI-Ram in the second-line treatment after a taxane-based chemotherapy in patients with advanced GEA.

METHODS

The RAMIRIS trial is a randomized, open-label, multicenter phase II/III study comparing treatment of FOLFIRI-Ram (arm A) with paclitaxel and ramucirumab (arm B). The Phase II is already closed with 111 enrolled patients. In the phase III, 318 taxane-pretreated patients with advanced GEA will be recruited and randomized 1:1 to FOLFIRI (5-FU 2400 mg/m2 over 46 h i.v., irinotecan 180 mg/m2 i.v.; 5-FU 400 mg/m2 bolus; leucovorin 400 mg/m2 i.v.; on day 1 and 15, q28) with ramucirumab 8 mg/kg every two weeks (Arm A) or paclitaxel 80 mg/m2 (days 1, 8, 15, q28) with ramucirumab 8 mg/kg every two weeks (Arm B). The primary endpoints are overall survival (OS) and objective overall response rate (ORR). Secondary endpoints are progression-free survival (PFS), disease control rate and safety and quality of life as assessed by EORTC-QLQ-C30 questionnaire.

DISCUSSION

The already completed RAMIRIS phase II demonstrated feasibility and efficacy of FOLFIRI-Ram. Especially docetaxel-pretreated patients seemed to markedly benefit from FOLFIRI-Ram, with favorable response- and PFS rates and lower toxicity. This offers a rationale for the phase III trial. If the RAMIRIS III trial transfers and confirms the results, they will affect the current treatment guidelines, recommending the combination therapy of FOLFIRI-Ram for taxane-pretreated patients with advanced GEA.

TRIAL REGISTRATION

NCT03081143 Date of registration: 13.11.2015.

Protocol of OGSG 1901: a phase II trial of ramucirumab plus irinotecan for patients with early relapsed gastric cancer during or after adjuvant docetaxel plus S - 1 therapy

BACKGROUND

Although docetaxel plus S-1 adjuvant chemotherapy after gastrectomy with D2 lymphadenectomy has been a standard of treatment for stage III gastric cancer, there is no established chemotherapy for patients with recurrence during or within six months after the completion of adjuvant docetaxel plus S-1 therapy.

METHODS

The OGSG 1901 trial is a prospective, open-label, multicenter, phase II trial evaluating ramucirumab plus irinotecan for gastric cancer patients with early relapse after adjuvant docetaxel plus S-1 therapy. The key eligibility criteria were: 1) histologically confirmed gastric adenocarcinoma 2) patients who were on docetaxel plus S-1 adjuvant chemotherapy after the confirmation of pathological stage III, 3) patients with early relapse, i.e., recurrence during or within 6 months after the completion of docetaxel plus S-1 therapy, and 4) patient with Eastern Cooperative Oncology Group performance status of 0-1. Irinotecan (150 mg/m2, day 1) and ramucirumab (8 mg/kg, day 1) will be administered every 2 weeks. The primary endpoint is overall survival, and the secondary endpoints are overall response rate, progression-free survival, and safety. The number of patients has been set at 40 based on the threshold and expected median survival times of 7 and 11 months, respectively, with a one-sided alpha error of 0.05 and power of 0.80. The enrollment and follow-up periods are 2 and 1.5 years, respectively.

DISCUSSION

The results of this trial will indicate whether the ramucirumab with irinotecan regimen has the potential to be a recommended treatment regimen for patients with recurrence gastric cancer during or within 6 months after the completion of adjuvant docetaxel plus S-1 therapy.

TRIAL REGISTRATION

This study was registered in the Japan Registry of Clinical Trials ( jRCTs05119071 , October 6, 2019).

The clinical position of ramucirumab-containing regimens for advanced gastric cancer: a review of clinical trial data

Despite the availability of multiple treatment options, the prognosis for advanced gastric cancer (AGC) remains poor and more effective treatment options are needed. Ramucirumab is an established and recommended second-line treatment for AGC. In recently completed and ongoing clinical trials, ramucirumab has been investigated in combination with new therapeutics and in new clinical settings to address the unmet treatment needs of AGC. In this review, the findings of recent clinical trials are discussed. The aims of this review are to present the current picture of ramucirumab-containing regimens in AGC and offer practical guidance on the clinical position and target populations of ramucirumab-containing regimens in light of emerging therapeutic developments.

Gastric Cancer, Version 2.2022, NCCN Clinical Practice Guidelines in Oncology

Gastric cancer is the third leading cause of cancer-related deaths worldwide. Over 95% of gastric cancers are adenocarcinomas, which are typically classified based on anatomic location and histologic type. Gastric cancer generally carries a poor prognosis because it is often diagnosed at an advanced stage. Systemic therapy can provide palliation, improved survival, and enhanced quality of life in patients with locally advanced or metastatic disease. The implementation of biomarker testing, especially analysis of HER2 status, microsatellite instability (MSI) status, and the expression of programmed death-ligand 1 (PD-L1), has had a significant impact on clinical practice and patient care. Targeted therapies including trastuzumab, nivolumab, and pembrolizumab have produced encouraging results in clinical trials for the treatment of patients with locally advanced or metastatic disease. Palliative management, which may include systemic therapy, chemoradiation, and/or best supportive care, is recommended for all patients with unresectable or metastatic cancer. Multidisciplinary team management is essential for all patients with localized gastric cancer. This selection from the NCCN Guidelines for Gastric Cancer focuses on the management of unresectable locally advanced, recurrent, or metastatic disease.

Salvage systemic therapy for advanced gastric and oesophago-gastric junction adenocarcinoma

BACKGROUND

Salvage systemic therapy has become the new standard of care in patients with advanced gastric and oesophago-gastric junction (OGJ) adenocarcinoma, following disease progression on first-line fluoropyrimidine and platinum-containing chemotherapy. Pharmacological agents proven to be effective in this setting include both chemotherapy and biological therapy, however, the consensus on the best salvage systemic therapy has not been reached.

OBJECTIVES

To assess the effects of systemic chemotherapy and biological therapy, either alone or in combination, on overall survival (OS) and progression-free survival (PFS) in patients with advanced gastric and OGJ adenocarcinoma, whose disease has progressed on, or relapsed after first-line fluoropyrimidine and platinum-containing chemotherapy. Adverse events (AEs), tumour response rate (TRR) and quality of life (QoL) associated with systemic chemotherapy and/or biological therapy were additionally assessed.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, trial registries and proceedings of the major oncology conferences up to October 2020. We additionally handsearched the reference lists of studies. No language restriction was applied.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing salvage systemic therapy (chemotherapy and/or biological therapy) and either another type of salvage systemic therapy, placebo, best supportive care (BSC) or no treatment in patients with gastric and OGJ adenocarcinoma refractory to first-line fluoropyrimidine and platinum-containing chemotherapy.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed selection of eligible studies and the primary author extracted study characteristics and outcome data from included studies. We assessed the quality and risk of bias of eligible studies according to the Cochrane Handbook for Systematic Reviews of Interventions. We expressed pooled estimates of effect using hazard ratio (HR) calculated using an inverse variance random-effects model for time-to-event data, and risk ratio (RR) calculated using Mantel-Haenszel random-effects model for binary data. The certainty of evidence was graded using GRADEpro.

MAIN RESULTS

We identified 17 RCTs with 5110 participants for inclusion in this review. Tweenty-nine studies are ongoing and twenty studies are awaiting classification. No studies examined the following comparisons: chemotherapy combined with biological therapy versus placebo, BSC or no treatment, chemotherapy combined with biological therapy versus biological therapy, biological therapy versus biological therapy and chemotherapy combined with biological therapy versus chemotherapy combined with biological therapy. Chemotherapy versus placebo, best supportive care or no treatment Chemotherapy probably improves OS (HR = 0.66, 95% CI 0.52 to 0.83, moderate-certainty evidence) based on two studies involving 547 participants and improves PFS (HR = 0.57, 95% CI 0.47 to 0.69, high-certainty evidence) based on one study involving 507 participants over placebo and BSC. Chemotherapy probably increases serious AEs (SAEs) (RR = 1.38, 95% CI 1.20 to 1.59, moderate-certainty evidence) based on one study involving 503 participants. Biological therapy versus placebo, best supportive care or no treatment Biological therapy improves OS (HR = 0.55, 95% CI 0.41 to 0.73, high-certainty evidence) and probably improves PFS (HR = 0.33, 95% CI 0.19 to 0.57, moderate-certainty evidence) over placebo based on three studies involving 781 participants. There is currently insufficient evidence for increased SAEs from biological therapy (RR = 1.14, 95% CI 0.95 to 1.37, low-certainty evidence) based on two studies involving 638 participants. Chemotherapy versus biological therapy This comparison only considered immunotherapy. There is probably no evidence of a difference for OS (HR = 0.82, 95% CI 0.66 to 1.02, moderate-certainty evidence) between chemotherapy and immunotherapy, and immunotherapy probably reduces PFS (HR = 1.27, 95% CI 1.03 to 1.57, moderate-certainty evidence) based on one study involving 395 participants. SAEs may be less frequent with immunotherapy compared to chemotherapy (RR = 0.41, 95% CI 0.30 to 0.57, low-certainty evidence). Chemotherapy combined with biological therapy versus chemotherapy Addition of biological therapy to chemotherapy probably does not improve OS (HR = 0.93, 95% CI 0.83 to 1.04, moderate-certainty evidence) and we are uncertain whether it improves PFS (HR = 0.87, 95% CI 0.74 to 1.02, very low-certainty evidence) based on seven studies involving 2743 participants. We are similarly uncertain whether combined chemotherapy and biological therapy increases SAEs (RR = 1.17, 95% CI 0.95 to 1.44, very low-certainty evidence) based on four studies involving 1618 participants. Chemotherapy versus chemotherapy There is no evidence of a difference for OS and PFS between irinotecan and paclitaxel (HR = 1.13, 95% CI 0.86 to 1.48, low-certainty evidence for OS; HR = 1.14, 95% CI 0.88 to 1.48, low-certainty evidence for PFS) based on one study involving 219 participants. Similarly, there is no evidence to indicate improved OS and PFS from addition of another chemotherapy to docetaxel (HR = 1.05, 95% CI 0.72 to 1.54, low-certainty evidence for OS; HR = 0.75, 95% CI 0.52 to 1.09, low-certainty evidence for PFS) based on two studies involving 121 participants. Grade ≥ 3 neutropenia occurred commonly with both mono- and poly-chemotherapy except for docetaxel-S1 and EOX chemotherapy.

AUTHORS' CONCLUSIONS

Survival outcome of patients with advanced gastric and OGJ adenocarcinoma whose disease progressed on first-line fluoropyrimidine and platinum-containing chemotherapy can be improved by chemotherapy and biological therapy. Biological therapy, in particular, achieves this without clear increase in SAEs or QoL impairment. Whether biological therapy is preferred over chemotherapy is still unclear and there is no evidence of a difference for OS outcome, although immunotherapy may be associated with less SAEs. Addition of biological therapy to chemotherapy and poly-chemotherapy are associated with frequent treatment-related toxicity without clear survival benefit.

Targeted and novel therapy in advanced gastric cancer

The systemic treatment options for advanced gastric cancer (GC) have evolved rapidly in recent years. We have reviewed the recent data of clinical trial incorporating targeted agents, including inhibitors of angiogenesis, human epidermal growth factor receptor 2 (HER2), mesenchymal-epithelial transition, epidermal growth factor receptor, mammalian target of rapamycin, claudin-18.2, programmed death-1 and DNA. Addition of trastuzumab to platinum-based chemotherapy has become standard of care as front-line therapy in advanced GC overexpressing HER2. In the second-line setting, ramucirumab with paclitaxel significantly improves overall survival compared to paclitaxel alone. For patients with refractory disease, apatinib, nivolumab, ramucirumab and TAS-102 have demonstrated single-agent activity with improved overall survival compared to placebo alone. Pembrolizumab has demonstrated more than 50% response rate in microsatellite instability-high tumors, 15% response rate in tumors expressing programmed death ligand 1, and non-inferior outcome in first-line treatment compared to chemotherapy. This review summarizes the current state and progress of research on targeted therapy for advanced GC.