Role of immunoglobulin G fragment C receptor polymorphism-mediated antibody-dependant cellular cytotoxicity in colorectal cancer treated with cetuximab therapy.

Antibody-dependent cellular cytotoxicity (ADCC), which is activated by effector cells via immunoglobulin G (IgG) fragment C receptors (FcRs), was proposed as a mechanism of cetuximab efficacy. Peripheral blood mononuclear cells (PBMCs) from 23 healthy donors and 13 patients with metastatic colorectal cancer (mCRC) treated with cetuximab were tested for FcγR polymorphisms and cetuximab-mediated ADCC. ADCC was measured by chromium-51 release on a epidermal growth factor receptor (EGFR)-positive human colon cancer cell line. Overall, 86 mCRC patients were genotyped for study purposes. PBMCs harbouring the FcγRIIIa 158 V/V genotype had a significantly higher cetuximab-mediated ADCC. No correlation was found between FcγR polymorphisms and response rate or time to progression after cetuximab-based therapy. Despite the in vitro analysis showing that the FcγRIIIa 158 V/V genotype is associated with higher ADCC, clinical data do not support a predictive role of FcγRIIIa polymorphisms in mCRC treated with cetuximab.

Comparison of HER2 status in primary and paired metastatic sites of gastric carcinoma.

BACKGROUND: Trastuzumab has recently shown efficacy in the treatment of HER2-positive advanced gastric adenocarcinoma. Although antibody-based therapies target the metastatic disease, HER2 status is usually evaluated in the primary tumour because metastatic sites are rarely biopsied. The aim of this study was to compare HER2 status in primary and paired metastatic sites of gastric adenocarcinoma. METHODS: The HER2 status was assessed by fluorescence in situ hybridisation (FISH) and immunohistochemistry (IHC) in 72 secondary lesions of gastric adenocarcinoma and in the corresponding primary tumours. RESULTS: Concordance of FISH results, evaluable in 68 primary and matched metastatic sites, was 98.5%. Concordance of IHC results, available in 39 of the 72 paired cases, was 94.9%. Only one case showed discordance between primary tumour and metastasis, being negative by both IHC and FISH in the primary and showing HER2 overexpression and amplification in the corresponding pancreatic lymph node metastasis. CONCLUSION: The high concordance observed between HER2 results obtained by both IHC and FISH on primary tumours and corresponding metastases suggests that in gastric cancer HER2 status is maintained in most cases unchanged during the metastatic process.

PTEN status in advanced colorectal cancer treated with cetuximab.

BACKGROUND: Loss of phosphatase and tensin homologue deleted in chromosome 10 (PTEN) function in advanced colorectal cancer (CRC) may represent one of the resistance mechanisms to cetuximab by interfering with the epidermal growth factor receptor signal transduction pathway. METHODS: PTEN expression tested by indirect immunofluorescence was evaluated both on primary (n=43) and on metastatic (n=24) sites in CRC patients treated with cetuximab. RESULTS: The loss of PTEN expression tested on metastatic sites was negatively associated with response (100% progressive disease (PD) in PTEN-negative cases vs 30% PD in PTEN-positive cases; P<0.05), PFS (0.8 vs 8.2 months; P<0.001) and OS (2.9 vs 14.2 months; P<0.001). CONCLUSION: A potential role of PTEN in the anti-tumour activity of cetuximab could be hypothesised.

Biological predictive factors in rectal cancer treated with preoperative radiotherapy or radiochemotherapy.

We analysed the expression of microsatellite instability, p53, p21, vascular endothelial growth factor and thymidylate synthase (TS) in pretreatment biopsy specimens from 57 locally advanced rectal cancers. The aim of the study was to correlate the expression of these markers with pathological response. Nineteen patients were treated with preoperative concomitant radiotherapy (RT) and fluorouracil/oxaliplatin-based chemotherapy (RCT), while 38 had RT alone. Pathological complete remission (pCR) and microfoci residual tumour (micR) occurred more frequently in patients treated with RCT (P=0.002) and in N0 tumours (P=0.004). Among patients treated with RCT, high TS levels were associated with a higher response rate (pCR+micR; P=0.015). No such correlation was found in the RT group. The other molecular factors were of no predictive value. Multivariate analysis confirmed a significant interaction between nodal status and the probability of achieving a pathological response (P=0.023) and between TS expression and treatment, indicating that a high TS level is predictive of a higher pathological response in the RCT subset (P=0.007). This study shows that lymph node status is the most important predictive factor of tumour response to preoperative treatment. Thymidylate synthase expression assessed immunohistochemically from pretreatment tumour biopsies may be a useful predictive marker of rectal tumour response to preoperative RCT.

Mucinous histology predicts for reduced fluorouracil responsiveness and survival in advanced colorectal cancer.

BACKGROUND: Mucinous carcinoma of the colon and rectum (mucinous CRC) is a histological subtype of colorectal adenocarcinoma for which there is little data on chemotherapy responsiveness. The purpose of this study was to investigate specifically the efficacy of fluorouracil-based first-line chemotherapy in patients with advanced mucinous CRC. PATIENTS AND METHODS: All patients with advanced mucinous CRC enrolled in three prospective randomized trials evaluating infused 5-fluorouracil as first-line treatment were compared with patients with non-mucinous subtypes enrolled in the same trials in a case-control study. Prognostic factors associated with overall response rate (ORR), progression-free survival (PFS) and overall survival (OS) were identified using univariate and multivariate logistic and/or Cox proportional hazards analyses. RESULTS: The study included 135 patients (45 cases and 90 controls). The response rates for cases and controls were 22% [95% confidence interval (CI), 11% to 38%] and 47% (95% CI, 36.1% to 58.2%), respectively (P=0.0058). Median OS for the mucinous CRC patients was 11.8 months (95% CI, 8.87-14.8) compared with 17.9 months (95% CI, 13.38-22.39) in the control group (univariate analysis, P=0.056); after correcting for significant prognostic factors by multivariate Cox regression analysis, P=0.0372 and hazard ratio (HR)=1.497 (1.02-2.19). CONCLUSION: Patients with advanced mucinous CRC have a poorer response to fluorouracil-based first-line chemotherapy and reduced survival compared with patients with non-mucinous CRC.