Pharmacogenetic variants associated with outcome in patients with advanced gastric cancer treated with fluoropyrimidine and platinum-based triplet combinations: a pooled analysis of three prospective studies.

The main treatment for advanced gastric cancer is fluoropyrimidine and platinum-based chemotherapy. We investigated the clinical validitiy of 19 candidate pharmacogenetic variants in ENOSF1 (enolase superfamily member 1), TYMS, CDA, MTHFR, TYMP, DPYD, ERCC1, ERCC2, GSTP1, GSTT1, GSTM1, CYP3A4 and CYP3A5 in relation to overall survival (OS), progression-free survival, objective response rate (ORR) and toxicity in 185 patients receiving triplet chemotherapy. The formal significance threshold was P<0.0026. TYMS VNTR (variable number of 28-bp tandem repeats) 3 R/3 R genotype was formally associated with inferior ORR (odds ratio (OR) 0.3, P=0.0025), whereas ENOSF1 rs2612091 G/G was nominally associated with OS after adjustment for TYMS 3 R/3 R (hazard ratio (HR) 1.5, P=0.041). In a subgroup analysis of patients with locally advanced disease (n=33), ENOSF1 rs2612091 was strongly associated with OS (HR 6.5, P=0.001). CYP3A4*22/CYP3A5*3 genotype was nominally associated with grade 3/4 toxicity in patients receiving docetaxel-containing chemotherapy (P=0.0175). This is the first study suggesting that ENOSF1 rs2612091 is prognostic or predictive of OS in gastric cancer. This finding requires prospective validation.

HPV-negative squamous cell carcinoma of the anal canal is unresponsive to standard treatment and frequently carries disruptive mutations in TP53.

BACKGROUND: Human papillomavirus (HPV), p16 expression, and TP53 mutations are known prognostic factors in head and neck squamous cell carcinoma, but their role in squamous cell carcinoma of the anal canal (SCCAC) is less well established. The objective of this study was to determine the prognostic significance of tumour HPV status, p16 and p53 expression, and mutations in TP53 in patients with SCCAC receiving (chemo)radiotherapy. METHODS: Human papillomavirus DNA was determined using an INNO-LiPA-based assay in tumour tissue of 107 patients with locally advanced SCCAC. Patients were treated with radiotherapy, with or without concurrent chemotherapy consisting of a fluoropyrimidine and mitomycin C. Expression of p16 and p53 was determined using immunohistochemistry. Exons 2-11 of TP53 in tumour tissue were sequenced. RESULTS: DNA of high-risk HPV types was detected in 93 out of 107 tumours (87%), all of which overexpressed p16 (HPV+/p16+). Of 14 HPV-negative (HPV-) tumours (13%), 10 (9%) were p16-negative (HPV-/p16-) and 4 (4%) overexpressed p16 (HPV-/p16+). Patients with HPV-/p16- disease had inferior 3-year locoregional control (LRC) (15%) compared with patients with HPV+/p16+ tumours (82%, P<0.001) and HPV-/p16+ tumours (75%, P=0.078). Similarly, 3-year overall survival (OS) was 35% (HPV-/p16-) vs 87% (HPV+/p16+, P<0.001) and 75% (HPV-/p16+, P=0.219). Disruptive mutations in TP53 were found in 80% of HPV-/p16- tumours vs 6% of HPV+/p16+ tumours (P<0.001). In multivariate analysis, HPV-/p16- status was an independent predictor of inferior LRC and OS. CONCLUSIONS: HPV- tumours are frequently TP53 mutated. HPV-/p16- status is a strong predictor for reduced LRC and OS, and alternative treatment strategies for patients with HPV-/p16- disease need to be explored.

Chemoradiotherapy with capecitabine for locally advanced anal carcinoma: an alternative treatment option.

BACKGROUND: Capecitabine is an established treatment alternative to intravenous 5-fluorouracil (5-FU) for patients with rectal cancer receiving chemoradiotherapy. Its place in the treatment of locally advanced anal carcinoma (AC), however, remains undetermined. We investigated whether capecitabine is as effective as 5-FU in the treatment of patients with locally advanced AC. METHODS: One hundred and five patients with squamous cell AC stage T2-4 (T2>4 cm), N0-1, M0 or T1-4, N2-3, M0, were included in this retrospective study. Forty-seven patients were treated with continuous 5-FU (750 mg m(-2)) on days 1-5 and 29-33, mitomycin C (MMC, 10 mg m(-2)) on day 1, and radiotherapy; 58 patients were treated with capecitabine (825 mg m(-2) b.i.d. on weekdays), MMC (10 mg m(-2)) on day 1, and radiotherapy. The primary end points of the study were: clinical complete response rate, locoregional control (LRC) and overall survival (OS). Secondary end points were: colostomy-free survival (CFS), toxicity and associations of genetic polymorphisms (GSTT1, GSTM1, GSTP1 and TYMS) with outcome and toxicity. RESULTS: Clinical complete response was achieved in 41/46 patients (89.1%) with 5-FU and in 52/58 patients (89.7%) with capecitabine. Three-year LRC was 76% and 79% (P=0.690, log-rank test), 3-year OS was 78% and 86% (P=0.364, log-rank test) and CFS was 65% and 79% (P=0.115, log-rank test) for 5-FU and capecitabine, respectively. GSTT1 and TYMS genotypes were associated with severe (grade 3-4) toxicity. CONCLUSIONS: Capecitabine combined with MMC and radiotherapy was equally effective as 5-FU-based chemoradiotherapy. This study shows that capecitabine can be used as an acceptable alternative to 5-FU for the treatment of AC.

Germline TYMS genotype is highly predictive in patients with metastatic gastrointestinal malignancies receiving capecitabine-based chemotherapy.

PURPOSE: This work was initiated to extend data on the effect of pharmacogenetics and chemotherapy pharmacokinetics (PK) on clinical outcome in patients with gastrointestinal malignancies. METHODS: We assessed 44 gene polymorphisms in 16 genes (TYMS, MTHFR, GSTP1, GSTM1, GSTT1, DPYD, XRCC1, XRCC3, XPD, ERCC1, RECQ1, RAD54L, ABCB1, ABCC2, ABCG2 and UGT2B7) in 64 patients with metastatic colorectal cancer (CRC) receiving capecitabine/oxaliplatin and 76 patients with advanced gastroesophageal cancer (GEC) receiving epirubicin/cisplatin/capecitabine, respectively. Plasma concentrations of anticancer drugs were measured for up to 24 h, and results were submitted to population PK analysis. We calculated the association between gene polymorphisms, chemotherapy exposure, tumor response, progression-free survival (PFS), overall survival (OS) and chemotherapy-related toxicity using appropriate statistical tests. RESULTS: Patients with a low clearance of 5FU were at increased risk of neutropenia (P < 0.05) and hand-foot syndrome (P = 0.002). DPYD T85C, T1896C and A2846T mutant variants were associated with diarrhea (P < 0.05) and HFS (P < 0.02), and IVS14+1G>A additionally with diarrhea (P < 0.001). The TYMS 2R/3G, 3C/3G or 3G/3G promoter variants were associated with worse PFS in the CRC (HR = 2.0, P < 0.01) and GEC group (HR = 5.4, P < 0.001) and worse OS in the GEC group (HR = 4.7, P < 0.001). The GSTP1 A313G mutant variant was associated with a higher PFS (HR = 0.55, P = 0.001) and OS (HR = 0.60, P = 0.002) in the CRC group. CONCLUSIONS: Germline polymorphisms of DPYD, TYMS and GSTP1 have a significant effect on toxicity and clinical outcome in patients receiving capecitabine-based chemotherapy for advanced colorectal or gastroesophageal cancer. These data should further be validated in prospective clinical studies.