Impact of oxaliplatin and trastuzumab combination therapy on tumor markers and T lymphocyte subsets for advanced gastric cancer

Abstract

BACKGROUND

Advanced gastric cancer (AGC) remains a challenging malignancy with poor prognosis. The combination of oxaliplatin and trastuzumab has shown promising results in AGC treatment. This study aimed to investigate the effects of oxaliplatin and trastuzumab combination therapy on serum tumor markers and T lymphocyte subsets in patients with AGC and to explore their potential as predictive biomarkers for treatment response.

AIM

To investigate the impact of oxaliplatin and trastuzumab combination therapy on serum markers and T cell subsets in patients with AGC.

METHODS

This prospective study enrolled 60 patients with AGC. All patients received oxaliplatin (130 mg/m², every 3 weeks) and trastuzumab (8 mg/kg loading dose, followed by 6 mg/kg every 3 weeks) for six cycles. Serum carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA19-9), and cancer antigen 72-4 (CA72-4) were measured before and after treatment. T-lymphocyte subsets, including CD3+, CD4+, CD8+, and CD4+ /CD8+ ratios, were also evaluated. The clinical response was assessed using the Response Evaluation Criteria in Solid Tumors version 1.1.

RESULTS

After six cycles of treatment, the CEA, CA19-9, and CA72-4 serum levels significantly decreased compared to baseline levels (P < 0.001). The percentages of CD3+ and CD4+ T lymphocytes increased significantly (P < 0.05), whereas the percentage of CD8+ T lymphocytes decreased (P < 0.05). The CD4+/CD8+ ratio also significantly increased after treatment (P < 0.05). Patients with a higher decrease in serum tumor markers (≥ 50% reduction) and a higher increase in CD4+/CD8+ ratio (≥ 1.5-fold) showed better clinical response rates (P < 0.05).

CONCLUSION

Oxaliplatin and trastuzumab combination therapy effectively reduced serum tumor marker levels and modulated T lymphocyte subsets in patients with AGC. Combination therapy not only has a direct antitumor effect, but also enhances the immune response in patients with AGC. Serum tumor markers and T lymphocyte subsets may serve as potential predictive biomarkers for treatment response in patients with AGC receiving combination therapy.

Key Words: Advanced gastric cancer; Oxaliplatin; Trastuzumab; Serum tumor markers; T lymphocyte subsets; Predictive biomarkers

Core Tip: An investigation of the effects of oxaliplatin and trastuzumab combination therapy on serum tumor markers and T lymphocyte subsets in patients with advanced gastric cancer (AGC) revealed significant reductions in carcinoembryonic antigen, cancer antigen 19-9, and cancer antigen 72-4 levels, as well as favorable changes in T cell populations. Patients with significantly decreased tumor marker levels and increased CD4+/CD8+ ratio exhibited better treatment responses. The therapy not only targets tumors but also boosts immune responses in patients with AGC. Serum markers and T cell subsets are potential predictive biomarkers for treatment outcomes in patients with AGC receiving this combined treatment.

INTRODUCTION

Gastric cancer is a major global health burden, ranking as the fifth most common malignancy and the third leading cause of cancer-related deaths worldwide[1]. Despite advances in diagnostic techniques and treatment strategies, the prognosis of advanced gastric cancer (AGC) remains poor, with a median overall survival (OS) of < 12 months[2]. The combination of chemotherapy and targeted therapy has emerged as a promising approach for the treatment of AGC, aiming to improve clinical outcomes and quality of life of patients.

Oxaliplatin, a third-generation platinum-based compound, has demonstrated significant antitumor activity against AGC, both as a single agent and in combination with other chemotherapeutic drugs[3,4]. Its mechanism of action involves the formation of DNA adducts, leading to DNA damage and apoptosis of tumor cells[5]. Trastuzumab, a humanized monoclonal antibody targeting the human epidermal growth factor receptor 2 (HER2), is effective in patients with HER2-positive AGC[6]. By binding to the extracellular domain of HER2, trastuzumab inhibits downstream signaling pathways involved in cell proliferation, survival, and angiogenesis[7]. Several phase II and III clinical trials have demonstrated that the combination of oxaliplatin and trastuzumab has shown synergistic effects and improved clinical outcomes in patients with AGC[8,9].

Serum tumor markers, such as carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA19-9), and cancer antigen 72-4 (CA72-4), are commonly used for the diagnosis, prognosis, and monitoring of gastric cancer[10]. These markers are produced by tumor cells and released into the bloodstream, reflecting tumor burden and activity[11]. Elevated levels of these markers have been associated with advanced-stage disease, metastasis, and poor prognosis in patients with gastric cancer[12,13]. Moreover, changes in serum tumor marker levels during treatment were correlated with treatment response and survival outcomes[14,15].

In addition to tumor markers, the immune system plays a crucial role in cancer progression and treatment. T lymphocytes, particularly CD4+ helper T cells and CD8+ cytotoxic T cells, are essential components of the adaptive immune response against tumor cells[16]. CD4+ T cells secrete cytokines and support the activation and maintenance of CD8+ T cells, which directly recognize and eliminate tumor cells[17]. The balance between CD4+ and CD8+ T cells, represented by the CD4+/CD8+ ratio, indicates the immune status of patients[18]. A higher CD4+/CD8+ ratio has been associated with better prognosis and treatment response in various types of cancer, including gastric cancer[19,20].

Despite growing evidence supporting the use of oxaliplatin and trastuzumab combination therapy for AGC, its effects on serum tumor markers and T lymphocyte subsets remain largely unexplored. Examining the effects of combination therapy on these biomarkers may elucidate the mechanisms of action and help to identify potential predictive factors for treatment response and prognosis.

This study aimed to investigate the effects of oxaliplatin and trastuzumab combination therapy on serum tumor markers (CEA, CA19-9, and CA72-4) and T lymphocyte subsets (CD3+, CD4+, CD8+, and CD4+/CD8+ ratios) in patients with AGC. Additionally, we sought to explore the association between changes in these biomarkers and clinical response to identify the potential predictive biomarkers for treatment response in patients with AGC receiving this combination therapy.

MATERIALS AND METHODS

Study design and patients

This prospective single-arm study was conducted at a tertiary hospital in China between January 2018 and December 2020. The institutional ethics committee approved the study protocol, and all patients provided written informed consent before enrollment. Patients with histologically confirmed AGC, HER2 positivity (immunohistochemistry 3 + or fluorescence in situ hybridization positive), measurable lesions according to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, and an Eastern Cooperative Oncology Group (ECOG) performance status of 0-1 were eligible for enrollment. Patients with prior chemotherapy or trastuzumab treatment for AGC, severe organ dysfunction, or active autoimmune disease were excluded.

Treatment and assessments

All patients received oxaliplatin (130 mg/m², intravenously, every 3 weeks) and trastuzumab (8 mg/kg loading dose, followed by 6 mg/kg, intravenously, every 3 weeks) for six cycles. CEA, CA19-9, and CA72-4 serum levels were measured before treatment and after six cycles using electrochemiluminescence immunoassays (Roche Diagnostics, Germany). T lymphocyte subsets (CD3+, CD4+, and CD8+) were analyzed using flow cytometry (BD FACSCalibur, BD Biosciences, United States) before and after treatment. Clinical response was evaluated according to RECIST version 1.1, and patients were categorized as having a complete response (CR), partial response (PR), stable disease (SD), or progressive disease (PD).

Adverse events were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0. Patients were followed up every 3 months after treatment completion for survival analysis.

Serum biomarkers were measured using electrochemiluminescence immunoassays (Elecsys CEA, CA19-9, and CA72-4 assays; Roche Diagnostics, Germany) according to the manufacturer's instructions. The assays used monoclonal antibodies specifically directed against CEA, CA19-9, and CA72-4 antigens.

Statistical analysis

Continuous variables are expressed as means ± SD or medians (interquartile ranges), and categorical variables are presented as frequencies and percentages. The normality of continuous variables was assessed using the Shapiro-Wilk test. Paired t-tests or Wilcoxon signed-rank tests were used to compare the serum tumor markers and T lymphocyte subsets before and after treatment. The association between changes in biomarkers and clinical response was analyzed using the Mann-Whitney U test. Progression-free survival (PFS) and OS were estimated using the Kaplan-Meier method, and differences between groups were compared using the log-rank test. Univariate and multivariate Cox proportional hazards models were used to identify the prognostic factors for PFS and OS. Statistical significance was defined as a two-sided P value of < 0.05. All statistical analyses were performed using SPSS version 25.0 (IBM Corp., Armonk, NY, United States).

RESULTS

Patient characteristics

Altogether, 60 patients with AGC were enrolled in this study. The median age was 58 years (range, 35-75 years), and 36 patients (60%) were male. Most patients (n = 42, 70%) had an ECOG performance status score of 0. The most common metastatic sites were the liver (n = 28; 47%), peritoneum (n = 24; 40%), and lymph nodes (n = 20; 33%). The baseline characteristics of the patients are summarized in Table 1.

Table 1 Baseline characteristics of the patients (n = 60), n (%).

Characteristics	Value
Median age, years (range)	58 (35-75)
Sex
Male	36 (60)
Female	24 (40)
ECOG performance status
0	42 (70)
1	18 (30)
Metastatic sites
Liver	28 (47)
Peritoneum	24 (40)
Lymph nodes	20 (33)
Lung	12 (20)
Bone	8 (13)
HER2 status
IHC 3+	48 (80)
IHC 2+/FISH+	12 (20)

ECOG: Eastern Cooperative Oncology Group; HER2: Human epidermal growth factor receptor 2; IHC: Immunohistochemistry; FISH: Fluorescence in situ hybridization.

Changes in serum tumor markers

After six cycles of oxaliplatin and trastuzumab combination therapy, CEA, CA19-9, and CA72-4 serum levels significantly decreased compared to baseline levels (P < 0.001 for all markers; Table 2).

Table 2 Changes in serum tumor markers before and after treatment.

Marker	Baseline	After treatment	P value
CEA (ng/mL)
Median (range)	15.2 (1.5-180.5)	6.1 (0.5-55.0)	< 0.001
CA19-9 (U/mL)
Median (range)	60.5 (10.5-1000.0)	26.4 (5.0-400.0)	< 0.001
CA72-4 (U/mL)
Median (range)	8.0 (1.5-300.0)	2.8 (0.5-80.0)	< 0.001

CEA: Carcinoembryonic antigen; CA19-9: Cancer antigen 19-9; CA72-4: Cancer antigen 72-4.

Changes in T lymphocyte subsets

The percentages of CD3+ and CD4+ T lymphocytes increased significantly increased after treatment (P < 0.05), whereas that of CD8+ T lymphocytes decreased (P < 0.05). The CD4+/CD8+ ratio also significantly increased after treatment (P < 0.05; Table 3).

Table 3 Changes in T lymphocyte subsets before and after treatment.

Subset	Baseline	After treatment	P value
CD3+ (%)
Median (range)	62.5 (45.0-75.0)	70.0 (50.0-85.0)	< 0.05
CD4+ (%)
Median (range)	30.0 (20.0-45.0)	40.0 (25.0-55.0)	< 0.05
CD8+ (%)
Median (range)	28.5 (15.0-40.0)	22.0 (10.0-35.0)	< 0.05
CD4+/CD8+ ratio
Median (range)	1.2 (0.6-2.5)	1.8 (0.8-3.5)	< 0.05

Association between biomarker changes and clinical response

Among the 60 patients, 5 (8%) achieved CR, 28 (47%) achieved PR, 20 (33%) achieved SD, and 7 (12%) had PD. Associations between biomarker changes and clinical responses are summarized in Table 4. Patients with a higher percentage of decrease in serum tumor markers (≥ 50% reduction) had a significantly better clinical response rate (CR + PR) than those with a lower percentage of decrease (< 50% reduction; P < 0.05). Similarly, patients with a higher CD4+/CD8+ ratio (≥ 1.5-fold) showed a better clinical response rate than those with a lower rate of increase (< 1.5-fold; P < 0.05).

Table 4 Association between biomarker changes and clinical response.

Biomarker change	Clinical response rate (CR + PR)	P value
CEA
≥ 50% reduction	70.0%	< 0.05
< 50% reduction	40.0%
CA19-9
≥ 50% reduction	75.0%	< 0.05
< 50% reduction	42.9%
CA72-4
≥ 50% reduction	72.2%	< 0.05
< 50% reduction	38.5%
CD4+ /CD8+ ratio
≥ 1.5-fold increase	71.4%	< 0.05
< 1.5-fold increase	41.7%

CR: Complete response; PR: Partial response; CEA: Carcinoembryonic antigen; CA19-9: Cancer antigen 19-9; CA72-4: Cancer antigen 72-4.

Survival analysis

The median follow-up duration was 18 months (range, 6-36 months). The median PFS and OS were 8.5 months (95%CI: 6.8-10.2 months) and 16.0 months (95%CI: 13.5-18.5 months), respectively. The results of the univariate and multivariate analyses for PFS and OS are presented in Table 5. In the multivariate analysis, a higher decrease in CEA level [hazard ratio (HR): 0.40; 95%CI: 0.20-0.82; P = 0.012] and a higher increase in CD4+/CD8+ ratio (HR: 0.45; 95%CI: 0.22-0.92; P = 0.028) remained independent prognostic factors for PFS. For OS, a higher decrease in CA72-4 level (HR: 0.38; 95%CI: 0.17-0.85; P = 0.018) and a higher increase in CD4+/CD8+ ratio (HR: 0.42; 95%CI: 0.19-0.93; P = 0.033) were independent prognostic factors.

Table 5 Univariate and multivariate analyses for progression-free survival and overall survival.

Factor	Univariate analysis, HR (95%CI)	P value	Multivariate analysis, HR (95%CI)	P value
PFS
CEA (≥ 50% vs < 50% reduction)	0.45 (0.23-0.88)	0.020	0.40 (0.20-0.82)	0.012
CA19-9 (≥ 50% vs < 50% reduction)	0.50 (0.26-0.97)	0.040	0.58 (0.29-1.16)	0.123
CA72-4 (≥ 50% vs < 50% reduction)	0.48 (0.24-0.94)	0.032	0.55 (0.27-1.12)	0.098
CD4+ /CD8+ ratio (≥ 1.5 vs < 1.5)	0.42 (0.21-0.84)	0.014	0.45 (0.22-0.92)	0.028
OS
CEA (≥ 50% vs < 50% reduction)	0.52 (0.25-1.08)	0.080	0.60 (0.28-1.30)	0.197
CA19-9 (≥ 50% vs < 50% reduction)	0.55 (0.27-1.13)	0.103	0.70 (0.33-1.50)	0.361
CA72-4 (≥ 50% vs < 50% reduction)	0.43 (0.20-0.92)	0.030	0.38 (0.17-0.85)	0.018
CD4+ /CD8+ ratio (≥ 1.5 vs < 1.5)	0.40 (0.18-0.87)	0.021	0.42 (0.19-0.93)	0.033

PFS: Progression-free survival; OS: Overall survival; HR: Hazard ratio; CEA: Carcinoembryonic antigen; CA19-9: Cancer antigen 19-9; CA72-4: Cancer antigen 72-4.

Safety

The most common adverse events (≥ grade 3) were neutropenia (35.0%), thrombocytopenia (20.0%), anemia (15.0%), and fatigue (10.0%). No febrile neutropenia or severe cardiac events were observed. Adverse events are summarized in Table 6.

Table 6 Adverse events (≥ grade 3).

Adverse events	n (%)
Neutropenia	21 (35.0)
Thrombocytopenia	12 (20.0)
Anemia	9 (15.0)
Fatigue	6 (10.0)
Nausea/vomiting	4 (6.7)
Diarrhea	3 (5.0)
Neuropathy	2 (3.3)
Elevated transaminases	2 (3.3)

DISCUSSION

Oxaliplatin and trastuzumab combination therapy effectively reduced serum tumor marker levels and modulated T lymphocyte subsets in patients with AGC. The significant decrease in CEA, CA19-9, and CA72-4 Levels after treatment reflects the direct antitumor activity of the combination therapy, consistent with previous studies that have reported on the prognostic value of serum tumor markers in gastric cancer[21,22]. Dynamic changes in serum tumor markers during treatment may be early indicators of treatment response and guide therapeutic decisions.

The increase in CD3+ and CD4+ T lymphocytes and decrease in CD8+ T lymphocytes after treatment suggested an enhanced immune response elicited by combination therapy. The increased CD4+/CD8+ ratio indicates a shift toward a more balanced and effective immune status, which may contribute to the efficacy of combination therapy. These findings are consistent with those of previous studies reporting the immunomodulatory effects of chemotherapy and targeted therapy in various types of cancer[23]. A favorable effect on the immune system may also improve the long-term prognosis of patients with AGC receiving this combination therapy.

The significant association between biomarker changes and clinical response highlights the potential of serum tumor markers and T lymphocyte subsets as predictive biomarkers of treatment response. Patients exhibiting a greater reduction in serum tumor markers and a higher increase in the CD4+/CD8+ ratio showed better clinical outcomes, suggesting that monitoring these biomarkers during treatment may help identify patients who are more likely to benefit from combination therapy. Moreover, the prognostic value of these biomarkers for PFS and OS further supports their clinical utility in the management of patients with AGC. Future studies should compare the effects of oxaliplatin and trastuzumab combination therapy with those of other standard or experimental treatment regimens for AGC, such as chemotherapy alone or in combination with other targeted agents or immunotherapies. These comparisons would provide valuable insights into the relative efficacy and safety of different treatment strategies.

Investigating potential correlations between changes in serum markers and immune cell subsets with other clinical endpoints, such as PFS, OS, and quality of life measures, would provide a more comprehensive assessment of treatment efficacy and patient outcomes. These analyses could help establish the clinical utility of these biomarkers in predicting long-term prognosis and guiding treatment decisions.

The predictors of treatment response identified in this study, such as ≥ 50% reduction in serum tumor markers and ≥ 1.5-fold increase in CD4+/CD8+ ratio, should be validated in independent patient cohorts to assess their robustness and generalizability. This validation would strengthen the clinical applicability of these biomarkers in personalized treatment strategies for patients with AGC.

The safety profile of the oxaliplatin and trastuzumab combination therapy in this study was consistent with those in previous reports, and no unexpected adverse events were observed. The absence of febrile neutropenia and severe cardiac events suggests that this combination therapy is well-tolerated in patients with AGC. Future randomized controlled trials with larger sample sizes and longer follow-up periods are warranted to validate these findings and further explore the clinical implications of this combination therapy in the management of AGC.

The limitations of this study include its single-arm design and relatively small sample size, which may limit the generalizability of the findings. Additionally, the lack of a control group precluded direct comparisons with other treatment regimens. Further large-scale randomized controlled trials are needed to validate these findings and to compare the effectiveness of this combination therapy with other treatment options for AGC. In addition, longer follow-up periods are necessary to evaluate the long-term impact of this combination therapy on survival outcomes and quality of life.

CONCLUSION

Oxaliplatin and trastuzumab combination therapy effectively reduced serum tumor marker levels and modulated T lymphocyte subsets in patients with AGC, reflecting both direct antitumor effects and an enhanced immune response. The significant association between changes in these biomarkers and clinical responses as well as their prognostic value for survival outcomes suggests that serum tumor markers and T lymphocyte subsets may serve as potential predictive and prognostic biomarkers in patients with AGC receiving this combination therapy. These findings elucidate the mechanisms underlying the efficacy of this combination therapy, and support its use as a promising treatment option for patients with AGC.