Low percentage of KRAS mutations revealed by locked nucleic acid polymerase chain reaction: implications for treatment of metastatic colorectal cancer.

Metastatic colorectal cancer (mCRC) is frequently characterized by the presence of mutations of the KRAS oncogene, which are generally associated with a poor response to treatment with anti-epidermal growth factor receptor (anti-EGFR) monoclonal antibodies. With the methods currently used, a case is classified as KRAS-mutated when approximately 20% of the cells bear an activating KRAS mutation. These considerations raise the question of whether cells with a mutated KRAS can be found in mCRC cases classified as KRAS wild-type when more sensitive methods are used. In addition, the issue arises of whether these mCRC cases with low proportion of KRAS-mutated cells could account at least in part for the therapeutic failure of anti-EGFR therapies that occur in 40-60% of cases classified as KRAS wild type. In this study, we compared the classical assays with a very sensitive test, a locked nucleic acid (LNA) polymerase chain reaction (PCR), capable of detecting KRAS-mutated alleles at extremely low frequency (detection sensitivity limit 0.25% mutated DNA/wild-type DNA). By analyzing a cohort of 213 mCRC patients for KRAS mutations, we found a 20.6% discordance between the sequencing/TheraScreen methods and the LNA-PCR. Indeed, 44 mCRC patients initially considered KRAS wild type were reclassified as KRAS mutated by using the LNA-PCR test. These patients were more numerous among individuals displaying a clinical failure to anti-EGFR therapies. Failure to respond to these biological treatments occurred even in the absence of mutations in other EGFR pathway components such as BRAF.

Definition of progression risk based on combinations of cellular and molecular markers in patients with Binet stage A chronic lymphocytic leukaemia.

IGHV mutational status and ZAP-70 or CD38 expression correlate with clinical course in B-cell chronic lymphocytic leukaemia (CLL). The three markers may be discordant in the single case and there is no consensus on their combined use in clinical practise. This multicenter study investigated this issue. Two-hundred and sixty-two Binet stage A patients were studied for the three markers. Sixty patients were profiled with HG-U133A gene expression chips. Disease progression was determined by time from diagnosis to treatment (TTT). The probability of being treatment-free at 3 years was significantly shorter in patients with unmutated IGHV genes (IGHVunmut 66% vs. 93%, chi square of log-rank = 30, P < 0.0001), ZAP-70 positive (ZAP-70pos 73% vs. 96%, chi square of log-rank = 8.2, P = 0.004) or CD38-positive cells (CD38pos 68% vs. 91%, chi square of log-rank = 21, P < 0.0001). Cox multivariate regression analysis showed that the three markers had an independent predictive value for TTT of similar power. A prognostic system based on presence of none (low-risk), one (intermediate-risk) or two or three (high-risk) markers was generated. Based on such criteria, 56%, 23% and 21% of cases were clustered in low (HR = 1), intermediate [HR = 2.8, 95% confidence interval (CI) 2.4-5.8] and high-risk group (HR = 8.0, 95% CI 3.9-16.2). Specific transcriptional patterns were significantly associated with risk groups.

Neoadjuvant treatment with single-agent cetuximab followed by 5-FU, cetuximab, and pelvic radiotherapy: a phase II study in locally advanced rectal cancer.

PURPOSE: Preoperative chemoradiotherapy followed by surgery represents the standard of care for locally advanced rectal cancer (LARC). Cetuximab has proved activity in advanced colorectal cancer, and its incorporation in preoperative treatment may increase tumor downstaging. METHODS AND MATERIALS: After biopsy and staging, uT3/uT4 N0/+ LARC received single-agent cetuximab in three doses, followed by weekly cetuximab plus 5-fluorouracil (5-FU), concomitantly with RT. Sample size was calculated according to Bryant and Day test, a two-stage design with at least 10 pathologic complete remissions observed in 60 patients (pts) able to complete the treatment plan. RESULTS: Forty pts with LARC were entered: male/female = 34/6; median age: 61 (range, 28-77); 12 uT3N0 Ed(30%); 25 uT3N1 (62%); 3 uT4N1 (8%); all Eastern Cooperative Oncology Group = 0. Thirty-five pts completed neoadjuvant treatment; 5 (12%) withdrew therapy after one cetuximab administration: three for hypersensitivity reactions, one for rapid progression, and one for purulent arthritis. They continued 5-FU in continuous infusion in association with RT. Thirty-one pts (77%) presented with acnelike rash; dose reduction/interruption of treatment was necessary in six pts (15%): two for Grade 3 acnelike rash, two for Grade 3 gastrointestinal toxicity, and two for refusal. Thirty-eight pts were evaluable for pathological response (one patient refused surgery, and one was progressed during neoadjuvant treatment). Pathological staging was: pT0N0 three pts (8%), pT1N0 1 pt (3%); pT2N0 13 pts (34%), and pT3 19 pts (50%) (N0:9, N1:5; N2:5); pT4 2 pts (5%). CONCLUSIONS: Preoperative treatment with 5-FU, cetuximab, and pelvic RT is feasible with acceptable toxicities; however, the rate of pathologic responses is disappointingly low.