Clinical Impact of Circulating Tumor RAS and BRAF Mutation Dynamics in Patients With Metastatic Colorectal Cancer Treated With First-Line Chemotherapy Plus Anti-Epidermal Growth Factor Receptor Therapy

PURPOSE

RAS and BRAF mutations can be detected as a mechanism of acquired resistance in circulating tumor (ct) DNA in patients with metastatic colorectal cancer treated with anti-epidermal growth factor receptor therapy.

METHODS

RAS and BRAF mutational status was assessed in ctDNA in a baseline plasma sample and a serum sample collected at the time of the last available determination (named secondary extraction) from patients with KRAS exon 2 wild-type metastatic colorectal cancer treated in two first-line prospective biomarker-designed clinical trials (PULSE, ClinicalTrials.gov identifier: NCT01288339; and POSIBA, ClincialTrials.gov identifier: NCT01276379).

RESULTS

Analysis of extended RAS and BRAF in tissue and plasma from 178 patients with KRAS exon 2 wild-type metastatic colorectal cancer showed a sensitivity of 64.1% and a specificity of 90%. The median overall survival (OS) of baseline patients with RAS and BRAF mutations in ctDNA was 22.3 months (95% CI, 15.6 to 29 months) and 8.9 months (95% CI, 6.3 to 11.4 months), respectively, which was significantly inferior to the median OS of 40.4 months (95% CI, 35.9 to 44.9 months) in two patients with wild-type disease (P < .001). Acquisition of RAS/BRAF mutations occurred in nine of 63 patients (14%) with progressive disease (PD; ie, blood draw within 1 month before PD or after PD) compared with six of 73 patients (8%) with no PD or blood extraction for ctDNA analysis before 1 month of PD (P = .47). Median OS in patients with RAS/BRAF acquisition was 23.9 months (95% CI, 19.7 to 27.9 months) compared with 40.6 months (95% CI, not reached to not reached) in patients who remained free of mutations (P = .016).

CONCLUSION

Our results confirm that baseline RAS and BRAF testing in ctDNA discriminates survival. The emergence of RAS/BRAF mutations has limited relevance for the time to progression to anti-epidermal growth factor receptor therapy.

Prospective Biomarker Study in Advanced RAS Wild-Type Colorectal Cancer: POSIBA Trial (GEMCAD 10-02)

This articles compares the capacity of several biomarkers (BRAF mutation, PIK3CA mutation/PTEN loss and DP phenotype) to predict 12‐month progression‐free survival and compares it with that of clinical variables

Background.

RAS testing is used to select patients with anti‐epidermal growth factor receptor (EGFR) therapies sensitivity in metastatic colorectal cancer (mCRC). However, other biomarkers such as BRAF, PIK3CA/PTEN, and p‐IGF‐1R+/MMP7+ (double positive [DP] phenotype) have not been prospectively assessed to predict anti‐EGFR resistance.

Materials and Methods.

We designed a multicenter prospective trial (NCT01276379) to evaluate whether the biomarkers BRAF mutation, PIK3CA mutation/PTEN loss, and DP phenotype can improve the prediction for 12‐months progression‐free survival (PFS) over the use of clinical variables exclusively in patients with RAS wild‐type (WT) mCRC treated with standard chemotherapy plus biweekly cetuximab as first‐line therapy. The planned sample size was 170 RAS WT patients to detect a 20% difference in 12‐month PFS based on the analysis of clinical and selected biomarkers (α = .05, β = .2). The discriminatory capacity of the biomarkers was evaluated using receiver operating characteristic curves.

Results.

We included 181 RAS WT patients. The biomarker distribution was as follows: BRAF mutant, 20 patients (11%); PIK3CA mutated/PTEN loss, 98 patients (58%); DP, 23 patients (12.7%). The clinical variables in the clinical score were progression status >0, left‐sided tumor, and resectable liver metastasis as the only metastatic site. The area under the curve (AUC) of the score containing the clinical variables was 0.67 (95% confidence interval [CI], 0.60–0.75). The AUC of the score with clinical variables and BRAF mutational status was 0.68 (0.61–0.75, p = .37). The AUC of the score with clinical variables and PI3KCA mutation/PTEN status was 0.69 (0.61–0.76, p = .32). The AUC of the score with clinical variables and DP phenotype was 0.66 (0.58–0.73, p = .09).

Conclusion.

The addition of BRAF, PIK3CA/PTEN, and DP to a clinical score does not improve the discrimination of 12‐month PFS.

Implications for Practice.

This prospective biomarker design study has important clinical implications because many prospective clinical trials are designed with the hypothesis that BRAF mutation per se and MEK and PIK3CA downstream pathways are critical for colorectal tumor survival. The results lead to the question of whether these pathways should be considered as passengers instead of drivers.

Guidelines for diagnosis, staging and treatment of metastatic colorectal cancer by Grupo Español Multidisciplinar en Cancer Digestivo (GEMCAD)

Abstract 

Advances in the care of patients with metastatic colorectal cancer arise from well-designed clinical trials. In the present document we address specific challenges in the design of clinical trials for metastatic colorectal cancer regarding staging and standard of care according to prognosis, as well as some relevant methodological issues.

Adjuvant treatment in resected non-small cell lung cancer: current and future issues

The cornerstone of treatment for early-stage non-small cell lung cancer (NSCLC) has been surgical resection. In the last five years two phase III trials have provided evidence of adjuvant platinum-based chemotherapy for completely resected stage II-IIIA patients. We review the evidence supporting adjuvant therapy in early-stage NSCLC; we discuss new issues surrounding adjuvant therapy such as treatment in the elderly-unfit population, treatment toxicity and its influence on outcomes, the importance of histology and gender in adjuvant treatment; and we discuss the future landscape of early-stage NSCLC research, namely, therapeutic strategies exploiting pharmacogenomic and gene-expression profiling, in an attempt to customize the treatment.

[Two cases of pituitary metastases as initial presentation form of small cell lung cancer]

Metastases in the sellar region are rare and are frequently found incidentally or in necropsies. Only 7% are reported to be symptomatic. Diabetes insipidus, anterior pituitary dysfunction, visual field defects, headache/pain and ophthalmoplegia are the most commonly reported symptoms. We present the cases of two male patients with a small-cell lung carcinoma whose first clinical symptoms were due to pituitary metastasis. One case presented with symptoms of cavernous sinus invasion and panhypopituitarism and the other case with diabetes insipidus. Both patients had a rapid progression of their disease despite chemotherapy and died after a few months. Pituitary metastases occur most commonly with breast cancer in women and lung cancer in men. The presence of polyuria and polydipsia in an oncologic patient should alert the physician for diabetes insipidus and, if confirmed, an imaging procedure of the pituitary gland is mandatory. Treatment for these tumors is often multimodal and includes surgery, radiation therapy, chemotherapy and hormone replacement. Although surgical series have not shown any significant survival benefits given by tumor resection, the patient's quality of life may be improved.