A Phase II Study of XELOX and Cetuximab as First-Line Therapy in Patients With KRAS Wild Type Metastatic Colorectal Cancer (FLEET2 Study)

Biweekly cetuximab in combination with capecitabine and oxaliplatin (XELOX) or irinotecan (XELIRI) in the first-line and second-line treatment of patients with RAS wild-type metastatic colorectal cancer

Background

Oral capecitabine in combination with intravenous oxaliplatin (XELOX) or irinotecan (XELIRI) are acceptable substitutions to fully intravenous regimens. Biweekly (as opposed to weekly) cetuximab is more convenient when combined with biweekly chemotherapy. Here, we report the tolerability and efficacy of biweekly cetuximab in combination with biweekly XELOX or XELIRI in patients with RAS wild-type metastatic colorectal cancer (RAS-WT mCRC).

Methods

Clinical data of consecutive patients with mCRC who received biweekly cetuximab (500 mg/m²) in combination with XELOX or XELIRI between January 2009 and May 2019 in the first- or second-line settings was extracted. Dosage of XEL (Capecitabine/XELODA) was 1,000 mg/m² twice daily for 9 days, plus on day 1 oxaliplatin 85 mg/m² or irinotecan 180 mg/m². Treatment dose reduction and delay for ≥7 days was analysed as surrogates for toxicity. Extended RAS testing was performed in the context of this study for patients who received treatment based on limited KRAS-WT genotype.

Results

Sixty one patients with RAS-WT mCRC fulfilled the eligibility criteria. XELOX was administered to 26 (42.6%) and XELIRI to 35 (57.4%) of patients. For all patients in the first-line setting, the objective response rate (ORR), median progression free survival (PFS) and median overall survival (OS) were 54%, 8 months and 25 months, respectively. The corresponding outcomes for the subgroup of patients who received first-line XELOX were 68%, 10 months and not reached, respectively. For all patients in the second-line setting, the ORR, PFS and OS were 50%, 7 months and 20 months, respectively. Chemotherapy components dose reduction and delays were observed in 18 (29.5%) and 25 (41%) patients, respectively. The corresponding frequencies for cetuximab were 3 (5%) and 31 (50.8%).

Conclusion

Biweekly cetuximab in combination with XELOX or XELIRI is tolerable and effective. The addition of cetuximab to capecitabine and oxaliplatin is associated with favourable outcome.

Efficacy and Safety of Cetuximab Dosing (biweekly vs weekly) in Patients with KRAS Wild-type Metastatic Colorectal Cancer: A Meta-analysis

BACKGROUND

Cetuximab 500 mg/m2 biweekly (Q2W) plus chemotherapy is commonly used and recommended by NCCN guidelines. This meta-analysis compares efficacy and safety between Q2W versus weekly (Q1W) cetuximab dosing.

METHODS

A systematic literature review was performed on Pubmed and RightFind (2007-2017) for patients with KRAS wild-type mCRC who received Q2W or Q1W cetuximab and other treatments. Observational studies and case reports were excluded. Randomized trials comparing Q2W and Q1W dosing, and single-arm trials with only Q2W schedule were included. CRYSTAL, a phase 3 randomized study with Q1W cetuximab dosing was paired with each single-arm study with a Q2W schedule and reweighted to achieve similar demographic/baseline characteristics. Overall survival (OS) and progression-free survival (PFS) with hazard ratios (HR), overall response rate (ORR) with odds ratios, and risk difference of adverse events of special interest (AESI) between Q2W versus Q1W cetuximab were analyzed.

RESULTS

Five phase 2 studies with cetuximab Q2W/Q1W dosing schedules were identified: CECOG (phase 2; Q2W, n = 77; Q1W, n = 75), NORDIC 7.5 (phase 2; Q2W, n = 152) and NORDIC 7 (arm C of phase 3; Q1W, n = 109), CELINE (n = 60), OPTIMIX (n = 99), and APEC (n = 289) all phase 2, Q2W, single-arm studies paired with CRYSTAL Q1W dosing (n = 303). Efficacy was similar between Q2W versus Q1W administration; OS HR = 0.96, 95% confidence interval (CI) [0.89, 1.04]; PFS HR = 0.96, 95% CI [0.87, 1.05]; ORR odds ratio 1.16, 95% CI [0.96, 1.41]. Mean differences (Q2W-Q1W) across AESI rates were not clinically meaningful with no obvious directionality.

CONCLUSION

This meta-analysis demonstrated no significant differences in efficacy and safety between Q2W versus Q1W cetuximab administration in mCRC patients.

Effects of different administration strategies of cetuximab on remission rate, MMPs, miR-106b-5p, PCAT-1, and adverse reactions in patients with RAS wild-type CRC liver metastasis

BACKGROUND

Colorectal cancer (CRC) has no obvious clinical symptoms at the initial stage of the disease, and it is often diagnosed at an advanced stage of pathology, with distant metastasis. The most common target organ of distant metastasis in CRC is the liver, and patients with liver metastasis have been shown to be well treated with biologic targeted agents in combination with FOLFIRI regimen.

AIM

To evaluate the efficacy and safety of different administ-ration strategies of cetuximab in patients with RAS wild-type CRC with liver metastasis.

METHODS

From July 2017 to March 2019, 74 patients with RAS wild-type CRC liver metastases treated with the FOLFOX regimen at our hospital were selected as the research subjects. According to the cetuximab administration strategy used, they were divided into either a weekly group or a bi-weekly group, with 37 cases in each group. The weekly group was initially given 400 mg/m² cetuximab by intravenous infusion over 120 min, followed by 250 mg/m² cetuximab once every week. The bi-weekly group was given 500 mg/m² cetuximab once every 2 wk. The disease remission rate, the incidence of toxic and side effects, the improvement of quality of life, the survival, and the expression of matrix metalloproteinases (MMPs), miR-106b-5p, and prostate cancer-related non-coding RNA transcript 1 (PCAT-1) before and after treatment were compared between the two groups.

RESULTS

The disease remission rate in the biweekly group was significantly higher than that of the weekly group (78.38% vs 54.05%, P < 0.05). The incidence of leukopenia and/or neutropenia, oral mucositis, and acne-like rash in the biweekly group was significantly higher than that of the weekly group (P < 0.05). The relative expression of MMP-2 and MMP-9 in the biweekly group was significantly lower than that in the weekly group, but the expression of tissue inhibitor of matrix metalloproteinases (T1MP) was significantly higher than that in the weekly group (P < 0.05). The relative expression of miR-106b-5p and PCAT-1 after treatment was significantly lower in both groups, and the decrease was significantly greater in the bi-weekly group (P < 0.05). The effective rate of improving the quality of life was significantly higher in the bi-weekly group than in the weekly group (72.97% vs 48.65%, P < 0.05), though there was no statistically significant difference in the progression-free survival time between the two groups (P > 0.05).

CONCLUSION

Cetuximab biweekly treatment of RAS wild-type CRC patients with liver metastases has better remission rate and quality of life improvement than weekly administration, but it increases the incidence of adverse reactions in patients. The administration strategy can be selected according to the patient's tolerance.

Severe interstitial pneumonia caused by cetuximab: a case report and review of the literature

Cetuximab is an IgG1 chimeric mAb against epidermal growth factor receptor, which can be used for chemotherapy failure or tolerance in patients with epidermal growth factor receptor expressed RAS wild-type metastatic colorectal cancer. We report on a patient who developed rapid-onset interstitial pneumonia while being treated with cetuximab plus XELOX (oxaliplatin, capecitabine) for metastatic colorectal cancer. A 75-year-old man patient was administered cetuximab plus XELOX regularly. After his cetuximab schedule was adjusted from 1 to 2 weeks, he rapidly developed interstitial pneumonia which led to acute respiratory distress syndrome. Our literature review indicated that, for patients with risk factors, a 2-week regimen of cetuximab might lead to interstitial pneumonia. Clinicians should closely monitor patients for adverse drug reactions to improve drug safety.

Biweekly Cetuximab Plus FOLFOX6 as First-Line Therapy in Patients With RAS Wild-Type Metastatic Colorectal Cancer: The CEBIFOX Trial

BACKGROUND

The multicenter, single-arm, phase II study CEBIFOX evaluated the efficacy of a biweekly cetuximab administration in combination with FOLFOX6 as first-line therapy in KRAS (exon 2) wild-type (wt) metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

Patients received FOLFOX6 with cetuximab (500 mg/m²) every second week. Primary endpoint was objective response rate (ORR), among others secondary endpoints were safety, progression-free survival (PFS), overall survival (OS), and patient-reported outcome (PRO). The impact on the treatment efficacy was evaluated in explorative subgroup analyses, including extended molecular profiling and primary tumor location.

RESULTS

In total, 57 were included in the intention-to-treat (ITT) analyses. New RAS mutations were detected in 14.0% by post hoc next-generation sequencing analysis in 43 patients. The ORR in the all RASwt population was 70.3% with a median PFS and OS of 10.9 (95% confidence interval [CI], 9.0-12.9) and 33.8 (95% CI, 21.1-45.5) months. Grade 3-5 adverse events occurred in 66.7% of the ITT, without significant impact on the PRO. Patients with right-sided primary tumors had a reduced ORR (54.5%), and median PFS and OS (10.1 and 23.8 months). BRAF mutations were detected in 11.3%. These patients had a significantly lower ORR, and median PFS and OS. Patients with RASwt/BRAFwt tumors had a notably high median PFS and OS of 14.3 and 38.9 months.

CONCLUSIONS

This study supports the efficacy and safety of biweekly cetuximab given in combination with FOLFOX6 in patients with RASwt/BRAFwt mCRC with left-sided primary tumor. CEBIFOX is the first trial reporting the complete dataset, including extended molecular profiling and tumor location of a biweekly administered cetuximab/FOLFOX6 in mCRC. Clinical trial number: NCT01051167.

Revisiting oral fluoropyrimidine with cetuximab in metastatic colorectal cancer: Real-world data in Chinese population

BACKGROUND

Cetuximab in combination with oral fluoropyrimidine (FP) remains controversial in metastatic colorectal cancer (mCRC). In view of the regional variation in the tolerability of FP, we conducted a retrospective analysis to compare oral FP with infusional FP in combination with cetuximab in Chinese population.

AIM

To compare the efficacy and safety profile of cetuximab in combination with oral FP and infusional FP in Chinese population in the real-world setting.

METHODS

A retrospective cohort study was done to analyse consecutive patients with Kras wild-type mCRC who received first-line treatment with cetuximab and FP-based chemotherapy in our unit from January 2010 to December 2015. Ninety-five eligible patients were included. The median follow-up of our cohort was 65.0 mo.

RESULTS

The median progression-free survival (mPFS) and median overall survival (mOS) of the entire cohort were 9.66 mo (95%CI: 7.72–12.5) and 25.8 mo (95%CI: 18.7–35.6), respectively. Between oral FP and infusional FP, there was no statistical significant difference in the mPFS [9.79 mo (95%CI: 7.49–12.7) vs 9.63 mo (95%CI: 6.34–13.4); P = 0.72] and mOS [25.8 mo (95%CI: 15.2–35.6) vs 26.3 mo (95%CI: 18.7–41.2); P = 0.63]. Grade 3 or above adverse events were reported in 28.4% of patients, being similar with oral and infusional FP, and included 10.5% of neutropenia and 2.1% of diarrhoea events.

CONCLUSION

The current analysis demonstrates comparable efficacy and safety profiles of cetuximab in combination with oral and infusional FP in Chinese population. The results expand treatment options for Chinese patients and invite revision of existing treatment guidelines to incorporate oral FP-based chemotherapy plus cetuximab.

Association between polymorphisms in EGFR and tumor response during cetuximab and oxaliplatin-based combination therapy in metastatic colorectal cancer: Analysis of data from two clinical trials

Predicting tumor response prior to starting anti-epidermal growth factor receptor (EGFR) antibody therapy would benefit patients with advanced/metastatic colorectal cancer (mCRC). The present study investigated the association between efficacy of cetuximab treatment and gene polymorphisms of fragment C γ receptor (FcγR) 2A, FcγR3A and EGFR in patients with extended RAS/BRAF wild-type mCRC. Clinical data and specimens were obtained from 90 patients who participated in either of two clinical studies evaluating the first-line, cetuximab plus oxaliplatin-based treatment. It was hypothesized that polymorphisms H/H of FcγR2A, V/V of FcγR3A, K/K of EGFR and <36 CA repeats in the EGFR gene may be associated with a favorable tumor response. Multivariate analysis demonstrated that patients with the H/H polymorphism tended to have an improved tumor response compared with the non-H/H population, although the result was not significant [odds ratio, 2.25; 95% confidence interval (CI), 0.89–5.66; P=0.09]. Univariate analysis revealed increased tumor shrinkage in patients with the K/K polymorphism of EGFR compared with the other polymorphisms (mean ± standard deviation, −55.3±28.4 vs. −39.6±40.8%; P=0.04). Subsequent multivariate analysis confirmed that the K/K polymorphism of EGFR predicted greater tumor shrinkage (multiple linear regression analysis estimate, −19.3; 95% CI, −35.5 to 3.0; P=0.02), with the tendency toward a preferable response in patients with <36 CA EGFR gene repeats (estimate, −16.9; 95% CI; −34.4 to 0.6; P=0.06). However, other polymorphisms and clinical variables did not predict tumor shrinkage. In conclusion, the present study demonstrated that polymorphisms of EGFR, FcγR2A and FcγR3A may differentiate the patients that obtain the maximum benefit from cetuximab treatment.

Multicenter phase II study of biweekly CAPIRI plus bevacizumab as second-line therapy in patients with metastatic colorectal cancer (JSWOG-C3 study)

Background

Triweekly capecitabine plus irinotecan (CAPIRI) was not a replacement for fluorouracil, leucovorin, and irinotecan (FOLFIRI) in the treatment of metastatic colorectal cancer (mCRC) because of the potential for greater toxicity. Recently, it has reported that mCAPIRI is well tolerated and non-inferior to FOLFIRI. In this study, we conducted a multicenter phase II trial to assess the efficacy and safety of biweekly CAPIRI plus bevacizumab as second-line chemotherapy for mCRC with reduced toxicity and preserved efficacy.

Methods

Patients with mCRC who had received prior chemotherapy, including oxaliplatin-based regimens, were eligible for this study. The treatment protocol administered capecitabine at 1000 mg/m² twice daily from the evening of day 1 to the morning of day 8, intravenous irinotecan at 150 mg/m² on day 1, and bevacizumab at 10 mg/kg on day 1 every 2 weeks. Primary endpoints for this study were progression-free survival (PFS) and safety. Secondary endpoints were overall survival (OS), time to treatment failure, response rate (RR), and disease control rate (DCR).

Results

Fifty-one patients were enrolled in this study. Median PFS was 5.5 months [95% confidence interval (CI) 4.23–7.40 months], and median OS was 13.5 months (95% CI 11.57–20.23 months). The RR was 14.6% (95% CI 6.5–28.4%), and the DCR was 66.7% (95% CI 51.5–79.2%). Hypertension was the most common Grade 3 adverse event (27.5%), followed by neutropenia (17.6%). Only two patients suffered from grade 3 hand–foot syndrome.

Conclusions

In mCRC patients, biweekly CAPIRI + bevacizumab appears effective and feasible as a second-line chemotherapy with relatively low toxicities, and has potential as a useful substitute for FOLFIRI + bevacizumab.

Observational study of first-line chemotherapy including cetuximab in patients with metastatic colorectal cancer: CORAL trial

Objective

We aimed to clarify the clinical practice and outcomes of first-line cetuximab-containing chemotherapy in patients with metastatic colorectal cancer. Efficacy and safety were evaluated in each group classified by the European Society for Medical Oncology Guidelines 2012.

Methods

This prospective observational study included patients with previously untreated metastatic colorectal cancer from 158 centers in Japan who started first-line cetuximab-containing chemotherapy from January 2012 to June 2013 and were followed for up to 3 years. The resection rates after chemotherapy were calculated and the overall survival was estimated using the Kaplan–Meier method for Group 1 (G1, potentially resectable), Group 2 (G2, not resectable and tumor-related symptoms) and Group 3 (G3, not resectable and asymptomatic).

Results

Of 578 patients, 562 were classified into G1 (n = 165), G2 (n = 224) or G3 (n = 173). The resection rate of any site was higher in G1 (57.0%) than in G2 (11.2%) and G3 (11.6%). G1, G2 and G3 showed median overall survivals (95% confidence interval) of 45.9 (38.1–not available), 16.7 (14.5–18.8) and 30.6 (23.2–34.8) months, respectively (P < 0.0001). The common tumor-related symptoms in G2 were pain, fatigue and anorexia, from which 31.7, 22.2 and 14.8% of the patients suffered at baseline.

Conclusions

The expected efficacy and safety of first-line cetuximab-containing chemotherapy were demonstrated in patients with metastatic colorectal cancer under clinical practice in Japan.

Registered clinical trial numbers

UMIN000007275

Efficacy of CapeOX plus Cetuximab Treatment as a First-Line Therapy for Patients with Extended RAS/BRAF/PIK3CA Wild-Type Advanced or Metastatic Colorectal Cancer

Background: Oxaliplatin and capecitabine (CapeOX) combined with cetuximab is rarely used to treat advanced and metastatic colorectal cancer (mCRC). The present study aimed to clarify the clinical benefits of this treatment regimen when used as a first-line therapy in patients with expanded RAS/BRAF/PIK3CA wild-type mCRC, using the data and tumor specimens from two previously published Phase II clinical trials.

Methods: The gene mutation status and clinical data of 102 patients with KRAS wild-type mCRC, who received either of CapeOX + cetuximab or FOLFOX + cetuximab, were analyzed. The primary endpoint was response rate (RR) of CapeOX + cetuximab treatment in patients with extended RAS/BRAF/PIK3CA wild-type mCRC. RR comparisons and maximum tumor size changes between different treatment regimens and gene mutation status were set as key secondary endpoints.

Results: We identified 88 patients with extended RAS/BRAF/PIK3CA wild-type mCRC. Those treated with CapeOX + cetuximab (n = 52) had a 61.5% RR (95% CI, 47.0-74.7%), while those treated with FOLFOX + cetuximab (n = 36) had a 66.7% RR (95% CI, 49.0-81.4%). Patients with any mutation (n = 14) had a 42.9% RR (95% CI, 17.1-71.1%). There were no significant differences between these three groups (P = 0.298). The disease control rate was 86.5% (95% CI, 74.2-94.4%) in the CapeOX + cetuximab group, and 88.9% (95% CI, 73.9-96.9%) in the FOLFOX + cetuximab group. Maximum tumor size changes were largest in patients with wild-type mCRC treated with FOLFOX + cetuximab followed by patients with wild-type mCRC treated with CapeOX + cetuximab, and then by those with any mutation (-63.2%, -52.6%, and -27.3%, respectively; P = 0.035).

Conclusions: Patients with RAS/BRAF/PIK3CA wild-type mCRC had a sufficient RR following first-line treatment with CapeOX + cetuximab. These results suggest that this combination therapy should be considered as a treatment option for patients with advanced mCRC.

Phase II study of panitumumab combined with capecitabine and oxaliplatin as first-line treatment in metastatic colorectal cancer patients: clinical results including extended tumor genotyping

This clinical trial assessed the efficacy and toxicity of panitumumab combined with oxaliplatin and capecitabine as first-line treatment in KRAS exon 2 wild-type metastatic colorectal cancer (mCRC) patients. Patients with exon 2 KRAS wild-type mCRC received panitumumab 9 mg/Kg, oxaliplatin 130 mg/m², and capecitabine 2000 mg/m² repeated every 3 weeks. The primary endpoint was objective response rate (ORR, minimum 42 responses). We retrospectively assessed mutations in genes implicated in CRC with massively parallel sequencing; ERBB2 and EGFR amplification with fluorescence in situ hybridization, and tumor-infiltrating lymphocyte density. Among 78 patients enrolled, 45 (57.7%) completed 6 cycles. Most common grade 3-4 toxicities were skin rash (19.2%), diarrhea (18%), and neuropathy (6.4%). Among 5 (6.4%) potentially treatment-related deaths, 2 (2.6%) were characterized toxic. Objective response occurred in 43 (55.1%) of the patients (complete 6.4% and partial response 48.7%; stable 17.9% and progressive disease 7.7%), while 3.8% were non-evaluable and 15% discontinued their treatment early. Additional mutations in KRAS/NRAS/BRAF were found in 11/62 assessable (18%) tumors. After 51 months median follow-up, median progression-free (PFS) was 8.1 and overall survival 20.2 months, independently of KRAS/NRAS/BRAF or PI3K-pathway mutation status. Patients with TP53 mutations (n = 34; 55%), as well as those with left colon primary tumors (n = 66; 85%), had significantly better PFS, also confirmed in multivariate analysis. Although the clinical trial met its primary endpoint, according to the current standards, the efficacy and tolerability of the drug combination are considered insufficient. Extended genotyping yielded interesting results regarding the significance of TP53 mutations.ClinicalTrials.gov identifier: NCT01215539, Registration date: Sep 29, 2010.

FOLFOX plus anti-epidermal growth factor receptor (EGFR) monoclonal antibody (mAb) is an effective first-line treatment for patients with RAS-wild left-sided metastatic colorectal cancer: A meta-analysis

BACKGROUND

The efficacy of oxaliplatin-based chemotherapy combined with anti-epidermal growth factor receptor (EGFR) monoclonal antibody (mAb) remains controversial in metastatic colorectal cancer (mCRC). This meta-analysis aims to estimate the effect of adding panitumumab or cetuximab to oxaliplatin-based chemotherapy in RAS wild type mCRC patients for the first-line treatment. The primary tumor location is also considered into this meta-analysis.

METHODS

RCT studies were identified by a search of MEDLINE, EMBASE, Cochrane library to October 2017, supplemented by manually retrieving ASCO, ESMO conference abstracts. The pooled hazard ratio (HR) for progression-free survival (PFS) and overall survival (OS), and pooled odds ratios (OR) for the overall response rate (ORR) were calculated by Review Manager 5.3.

RESULTS

The results indicated that the addition of anti-EGFR mAbs to FOLFOX regimen in RAS wild-type mCRC patients for the first-line treatment resulted in considerable improvements in PFS (HR = 0.70; 95% confidence interval [CI]: 0.59-0.82; P < .0001), OS (HR = 0.79; 95%CI: 0.67-0.92; P = .003), and ORR (OR = 2.56; 95% CI: 1.77-3.70; P < .00001) compared with chemotherapy alone. However, in RAS/BRAF wild patients, no significant differences were observed when anti-EGFR mAb was added to FLOX or XELOX regimen compared with chemotherapy alone with regard to OS and PFS, whereas FOLFOX+anti-EGFR mAb showed a marked superior OS and PFS (OS, HR = 0.77; 95% CI: 0.61-0.98; P = .03; PFS, HR = 0.68; 95% CI: 0.57-0.82; P < .00001). A meta-analysis including TAILOR and PRIME study suggests that primary tumor location (PTL) predicted a survival benefit when adding the EGFR antibody to FOLFOX regimen in RAS-wild mCRC patients (OS, HR for left-sided: 0.71; 95% CI: 0.59-0.85; P = .0002 and HR for right-sided: 0.90; 95% CI: 0.65-1.25; P = .53). However, the HR for PFS and ORR still suggests a benefit from the addition of anti-EGFR mAb in right-sided mCRC patients.

CONCLUSION

So these results suggest anti-EGFR mAb and oxaliplatin are good partners in the FOLFOX regimen. The addition of EGFR antibody to FOLFOX markedly improved efficacy in RAS-wild patients with left-sided mCRC. In RAS/BRAF-wild patients, the efficacy is similar. For patients with right-sided tumor, a benefit showing a trendency in favor of anti-EGFR mAb can still seen. The molecular characteristics behind the tumor location need to be more explored urgently.

Cetuximab strongly enhances immune cell infiltration into liver metastatic sites in colorectal cancer

Cetuximab has activity against colorectal cancers. Recent studies demonstrated that cetuximab induces antibody-dependent cell-mediated cytotoxicity via immune cells, and a new immune-related mechanism of inducing immunogenic cell death. This study aimed to evaluate the immune responses induced by cetuximab in tumor microenvironments at liver metastasis sites of metastatic colorectal cancer patients. We assessed immune cell infiltration in the liver metastatic sites of 53 colorectal cancer patients. These patients were divided into three groups according to the treatment before operation: chemotherapy with cetuximab, chemotherapy without cetuximab, and no chemotherapy. The inflammatory cells in the liver metastatic sites were assessed by hematoxylin-eosin staining, focusing on the invasive margin. The overall inflammatory reaction and number of lymphoid cells were assessed with a four-point scoring system. We then assessed immune cell infiltration (CD3, CD8 and CD56) in 15 liver metastatic sites. Hematoxylin-eosin staining demonstrated more inflammatory cells in the chemotherapy with cetuximab group than in the other groups (P < 0.001). Of note, inflammatory cells were found in intratumoral areas, and the destruction of cancer cell foci was observed in the chemotherapy with cetuximab group. Moreover, a higher infiltration of CD3+ (P = 0.003), CD8+ (P = 0.003) and CD56+ (P = 0.001) cells was observed in the chemotherapy with cetuximab group than in the other groups. These results suggest that cetuximab might have an immune-enhancing effect. As such, the immune-related mechanism of action of cetuximab may enhance the efficacy of combination therapy, such as chemotherapy and immunotherapy using therapeutic peptides.