Phase II study of high-sensitivity genotyping of KRAS, NRAS, BRAF and PIK3CA to ultra-select metastatic colorectal cancer patients for panitumumab plus FOLFIRI: the ULTRA trial.

BACKGROUND: Several studies show the importance of accurately quantifying not only KRAS and other low-abundant mutations because benefits of anti-EGFR therapies may depend on certain sensitivity thresholds. We assessed whether ultra-selection of patients using a high-sensitive digital PCR (dPCR) to determine KRAS, NRAS, BRAF and PIK3CA status can improve clinical outcomes of panitumumab plus FOLFIRI. PATIENTS AND METHODS: This was a single-arm phase II trial that analysed 38 KRAS, NRAS, BRAF and PIK3CA hotspots in tumour tissues of irinotecan-resistant metastatic colorectal cancer patients who received panitumumab plus FOLFIRI until disease progression or early withdrawal. Mutation profiles were identified by nanofluidic dPCR and correlated with clinical outcomes (ORR, overall response rate; PFS, progression-free survival; OS, overall survival) using cut-offs from 0% to 5%. A quantitative PCR (qPCR) analysis was also performed. RESULTS: Seventy-two evaluable patients were enrolled. RAS (KRAS/NRAS) mutations were detected in 23 (32%) patients and RAS/BRAF mutations in 25 (35%) by dPCR, while they were detected in 7 (10%) and 11 (15%) patients, respectively, by qPCR. PIK3CA mutations were not considered in the analyses as they were only detected in 2 (3%) patients by dPCR and in 1 (1%) patient by qPCR. The use of different dPCR cut-offs for RAS (KRAS/NRAS) and RAS/BRAF analyses translated into differential clinical outcomes. The highest ORR, PFS and OS in wild-type patients with their lowest values in patients with mutations were achieved with a 5% cut-off. We observed similar outcomes in RAS/BRAF wild-type and mutant patients defined by qPCR. CONCLUSIONS: High-sensitive dPCR accurately identified patients with KRAS, NRAS, BRAF and PIK3CA mutations. The optimal RAS/BRAF mutational cut-off for outcome prediction is 5%, which explains that the predictive performance of qPCR was not improved by dPCR. The biological and clinical implications of low-frequent mutated alleles warrant further investigations. CLINICALTRIALS.GOV NUMBER: NCT01704703. EUDRACT NUMBER: 2012-001955-38.

Should we continue temozolomide beyond six cycles in the adjuvant treatment of glioblastoma without an evidence of clinical benefit? A cost analysis based on prescribing patterns in Spain.

PURPOSE: The standard adjuvant treatment for glioblastoma is temozolomide concomitant with radiotherapy, followed by a further six cycles of temozolomide. However, due to the lack of empirical evidence and international consensus regarding the optimal duration of temozolomide treatment, it is often extended to 12 or more cycles, even in the absence of residual disease. No clinical trial has shown clear evidence of clinical benefit of this extended treatment. We have explored the economic impact of this practice in Spain. MATERIALS AND METHODS: Spanish neuro-oncologists completed a questionnaire on the clinical management of glioblastomas in their centers. Based on their responses and on available clinical and demographic data, we estimated the number of patients who receive more than six cycles of temozolomide and calculated the cost of this extended treatment. RESULTS: Temozolomide treatment is continued for more than six cycles by 80.5 % of neuro-oncologists: 44.4 % only if there is residual disease; 27.8 % for 12 cycles even in the absence of residual disease; and 8.3 % until progression. Thus, 292 patients annually will continue treatment beyond six cycles in spite of a lack of clear evidence of clinical benefit. Temozolomide is covered by the National Health Insurance System, and the additional economic burden to society of this extended treatment is nearly 1.5 million euros a year. CONCLUSIONS: The optimal duration of adjuvant temozolomide treatment merits investigation in a clinical trial due to the economic consequences of prolonged treatment without evidence of greater patient benefit.