Background: KRAS codons 12 and 13 mutations predict resistance to anti-EGFR monoclonal antibodies (moAbs) in metastatic colorectal cancer. Also, BRAF V600E mutation has been associated with resistance. Additional KRAS mutations are described in CRC. Methods: We investigated the role of KRAS codons 61 and 146 and BRAF V600E mutations in predicting resistance to cetuximab plus irinotecan in a cohort of KRAS codons 12 and 13 wild-type patients. Results: Among 87 KRAS codons 12 and 13 wild-type patients, KRAS codons 61 and 146 were mutated in 7 and 1 case, respectively. None of mutated patients responded vs 22 of 68 wild type (P=0.096). Eleven patients were not evaluable. KRAS mutations were associated with shorter progression-free survival (PFS, HR: 0.46, P=0.028). None of 13 BRAF-mutated patients responded vs 24 of 74 BRAF wild type (P=0.016). BRAF mutation was associated with a trend towards shorter PFS (HR: 0.59, P=0.073). In the subgroup of BRAF wild-type patients, KRAS codons 61/146 mutations determined a lower response rate (0 vs 37%, P=0.047) and worse PFS (HR: 0.45, P=0.023). Patients bearing KRAS or BRAF mutations had poorer response rate (0 vs 37%, P=0.0005) and PFS (HR: 0.51, P=0.006) compared with KRAS and BRAF wild-type patients. Conclusion: Assessing KRAS codons 61/146 and BRAF V600E mutations might help optimising the selection of the candidate patients to receive anti-EGFR moAbs.

Scientific data provide the evidence that secondary K-RAS mutations do not occur during anti-epidermal growth factor receptor therapy in colorectal cancer patients. This multicenter phase II prospective study aims to investigate the activity of a retreatment with a cetuximab-based therapy. We enrolled 39 irinotecan-refractory patients who had a clinical benefit after a line of cetuximab- plus irinotecan-based therapy and then a progression of disease for which underwent a new line chemotherapy and finally, after a clear new progression of disease, were retreated with the same cetuximab- plus irinotecan-based therapy. Median number of therapeutic lines before accrual was 4. Median interval time between last cycle of first cetuximab-based therapy and first cycle of the retreatment was 6 months. Overall response rate was 53.8% with 19 partial responses (48.7%) and 2 complete responses (5.1%). Disease stabilization was obtained in 35.9% of patients and progression in four patients (10.2%). Median progression-free survival was 6.6 months. The correlation between skin toxicity during first cetuximab therapy and during cetuximab rechallenge was significant (P = 0.01). Rechallenge with the same cetuximab-based therapy may achieve a new important clinical benefit further delaying the progression of disease and improving the therapeutic options.

Purpose: Approximately 30% to 40% patients with a superficial bladder cancer treated with Bacille Calmette-Guerin (BCG) or epirubicin do not respond; of the initial responders, 35% have a relapse within 5 years. We compare the therapeutic efficacy and toxicity of intravescical infusions of gemcitabine (GEM) with mitomycin (MMC) in patients with a recurrent superficial bladder cancer.Patients and Methods: Patients with a history of a previously treated, recurrent Ta-T1, G1-G3 bladder transitional cell carcinoma were enrolled in the study. The patients received a 6-week course of GEM infusions or 4-week course of MMC. In both arms, for the initial responders who remained free of recurrences, maintenance therapy consisted of 10 monthly treatments during the first year.Results: A total of 120 patients were enrolled and randomly assigned to either the MMC or GEM treatment arm. At the end of the study, 109 patients (55 in MMC and 54 in GEM) were assessable. The median duration of follow-up was 36 months for either arm. In the GEM arm, 39 (72%) of 54 patients remained free of recurrence versus 33 (61%) of 55 in MMC arm. Among patients with recurrences, 10 in the MMC arm and six in the GEM arm also had a progressive disease by stage. The incidence of chemical cystitis in the MMC arm was statistically higher than in the GEM arm (P = .012).Conclusion: This study demonstrates that GEM has better efficacy and lower toxicity than MMC; therefore, GEM appears as a logical candidate for intrabladder therapy in patients with refractory transitional cancer.