Plasma ctDNA RAS mutation analysis for the diagnosis and treatment monitoring of metastatic colorectal cancer patients

Background

RAS assessment is mandatory for therapy decision in metastatic colorectal cancer (mCRC) patients. This determination is based on tumor tissue, however, genotyping of circulating tumor (ct)DNA offers clear advantages as a minimally invasive method that represents tumor heterogeneity. Our study aims to evaluate the use of ctDNA as an alternative for determining baseline RAS status and subsequent monitoring of RAS mutations during therapy as a component of routine clinical practice.

Patients and methods

RAS mutational status in plasma was evaluated in mCRC patients by OncoBEAM™ RAS CRC assay. Concordance of results in plasma and tissue was retrospectively evaluated. RAS mutations were also prospectively monitored in longitudinal plasma samples from selected patients.

Results

Analysis of RAS in tissue and plasma samples from 115 mCRC patients showed a 93% overall agreement. Plasma/tissue RAS discrepancies were mainly explained by spatial and temporal tumor heterogeneity. Analysis of clinico-pathological features showed that the site of metastasis (i.e. peritoneal, lung), the histology of the tumor (i.e. mucinous) and administration of treatment previous to blood collection negatively impacted the detection of RAS in ctDNA. In patients with baseline mutant RAS tumors treated with chemotherapy/antiangiogenic, longitudinal analysis of RAS ctDNA mirrored response to treatment, being an early predictor of response. In patients RAS wt, longitudinal monitoring of RAS ctDNA revealed that OncoBEAM was useful to detect emergence of RAS mutations during anti-EGFR treatment.

Conclusion

The high overall agreement in RAS mutational assessment between plasma and tissue supports blood-based testing with OncoBEAM™ as a viable alternative for genotyping RAS of mCRC patients in routine clinical practice. Our study describes practical clinico-pathological specifications to optimize RAS ctDNA determination. Moreover, OncoBEAM™ is useful to monitor RAS in patients undergoing systemic therapy to detect resistance and evaluate the efficacy of particular treatments.

PrediCTC, liquid biopsy in precision oncology: a technology transfer experience in the Spanish health system

PURPOSE

Management of metastatic disease in oncology includes monitoring of therapy response principally by imaging techniques like CT scan. In addition to some limitations, the irruption of liquid biopsy and its application in personalized medicine has encouraged the development of more efficient technologies for prognosis and follow-up of patients in advanced disease.

METHODS

PrediCTC constitutes a panel of genes for the assessment of circulating tumor cells (CTC) in metastatic colorectal cancer patients, with demonstrated improved efficiency compared to CT scan for the evaluation of early therapy response in a multicenter prospective study. In this work, we designed and developed a technology transfer strategy to define the market opportunity for an eventual implementation of PrediCTC in the clinical practice.

RESULTS

This included the definition of the regulatory framework, the analysis of the regulatory roadmap needed for CE mark, a benchmarking study, the design of a product development strategy, a revision of intellectual property, a cost-effectiveness study and an expert panel consultation.

CONCLUSION

The definition and analysis of an appropriate technology transfer strategy and the correct balance among regulatory, financial and technical determinants are critical for the transformation of a promising technology into a viable technology, and for the decision of implementing liquid biopsy in the monitoring of therapy response in advanced disease.

Pharmacogenomics in colorectal cancer: a genome-wide association study to predict toxicity after 5-fluorouracil or FOLFOX administration

The development of genotyping technologies has allowed for wider screening for inherited causes of variable outcomes following drug administration. We have performed a genome-wide association study (GWAS) on 221 colorectal cancer (CRC) patients that had been treated with 5-fluorouracil (5-FU), either alone or in combination with oxaliplatin (FOLFOX). A validation set of 791 patients was also studied. Seven SNPs (rs16857540, rs2465403, rs10876844, rs10784749, rs17626122, rs7325568 and rs4243761) showed evidence of association (pooled P-values 0.020, 9.426E-03, 0.010, 0.017, 0.042, 2.302E-04, 2.803E-03) with adverse drug reactions (ADRs). This is the first study to explore the genetic basis of inter-individual variation in toxicity responses to the administration of 5-FU or FOLFOX in CRC patients on a genome-wide scale.

A retrospective observational study on the safety and efficacy of first-line treatment with bevacizumab combined with FOLFIRI in metastatic colorectal cancer

BACKGROUND

Combination of bevacizumab and FOLFIRI has currently become one of the standard therapeutic regimens. However, published information is still limited. The objective of the present retrospective observational study is to analyse the response and toxicity of first-line treatment with FOLFIRI+bevacizumab in patients with metastatic colorectal cancer (mCRC).

METHODS

Data were collected from patients from nine Spanish sites diagnosed with mCRC, ECOG≤2, whose first treatment for advanced disease was at least three cycles of FOLFIRI+bevacizumab.

RESULTS

A total of 95 patients were enrolled into the study: 64.2% males, median age of 59 years (53.2-67.1 years), ECOG=0-1 in 96.9% of patients. The main site of primary tumour was the colon (69.7%), and most metastases occurred in the liver (71.6%). Clinical benefit was detected in 67.4% (57.0-76.6; 95% confidence interval (CI)), with 8.4% of CR and 42.1% of PR. Median TTP was 10.6 months (10.0-11.3; 95% CI), PFS was 10.6 months (9.8-11.3; 95% CI), and OS was 20.7 months (17.1-24.2; 95% CI). Main grade I-II toxicities included haematological toxicity (35.8%), diarrhea (27.3%), mucositis (25.3%), asthenia (19.0%), haemorrhages (11.6%), and emesis (10.6%). Toxicities reaching grades III-IV were haematological toxicity (9.5%), diarrhea (8.5%), mucositis (5.3%), hepatic toxicity (2.1%), asthenia (2.1%), proteinuria (1.1%), emesis (1.1%), pain (1.1%), and colics (1.1%).

CONCLUSION

Results of this study support the beneficial effect of adding bevacizumab to FOLFIRI regimen in terms of efficacy and show a favourable tolerability profile.

Phase II study of biweekly XELOX (capecitabine and oxaliplatin) as first line chemotherapy in elderly patients with metastatic colorectal cancer

e15053

Background: Analysis of efficacy and toxicity of biweekly XELOX as first line monotherapy in elderly patients (pts) with metastatic colorectal cancer (MCRC), based in results of W. Scheithauer (J Clin Oncol 2003; 21: 1307). Methods: From March/06 to November/08, 28 chemonaïve elderly pts (>75 years old) with MCRC, PS: 0–2, and adequate renal, hepatic and bone marrow functions, were included in a phase II study of: oxaliplatin 85 mg/ m2/ day 1 plus capecitabine 2000/ m2/ in 2 divided doses/ days 1–7 every 2 weeks. Treatment was continued until 12 cycles, tumour progression or innaceptable toxicity. Response evaluation every 6 cycles and toxicity every cycle was performed. At present 28 pts for toxicity and 24 pts for response are evaluable. Results: Median age: 78.2 years (range: 73.5–79.5). Male/Female: 14/14. Rectal/Colon: 9/19. Metastatic sites 1/2/>2: 15/6/6. Liver 78.6%, Lung 32.1%, Local tumour 7.1%, Retroperitoneum 14.2%, Peritoneum 10.7%. and Bones 7.1 %. Previous adjuvant with 5-FU regimens to 4 pts. Comorbidity grade by Charlson index 0–1/2/>2: 60.8%/ 28.6% / 10.7%, respectively. Median number of cycles for oxaliplatin and capecitabine were 8 (5.25–12) and 8 (5.25–11.75). Response rate: 2 pts complete response (8.3%), 8 pts partial response (33.3%),10 pts stable disease (41.7 %) and 4 pts progression (16.7%). The main CTC toxicity was Asthenia G2+3 in 6 (21.5%), Nausea and emesis G2 in 7 (25%), Diarrhea G2+3 in 7 (25%) and Hand-foot syndrome G1+2 in 5 pts (17.8%). No G4 toxicity or toxic deaths were observed. Median time to progression was 8.6 months.Median overall survival will be given updated at the congress. Conclusions: Preliminary results suggest that bi-weekly XELOX is an effective first line treatment for MCRC in elderly pts with an acceptable toxicity profile (especial surveillance of diarrhea is necessary) and protocol cumpliment. Combination with bevacizumab should be considered.

No significant financial relationships to disclose.

Multicenter phase II study of cetuximab and irinotecan as third line chemotherapy in patients (pts) with metastatic colorectal cancer (MCRC) previously treated with both irinotecan and oxaliplatin regimens

13551

Background: Pts with chemotherapy-resistant MCRC have a really poor prognosis with few therapeutic options. Cetuximab (Erbitux®) is an IgG1 monoclonal antibody targeting the EGFR, shown to be effective in pts with EGFR-expressing MCRC refractory to prior irinotecan-based chemotherapy (Cunningham NEJM 2004). Methods: The goal of this multicenter phase II study is to investigate the safety and efficacy of cetuximab in combination with irinotecan as third line treatment in 40 pts with heavily pre-treated MCRC. From Jan to Dec 2005, 40 pts with EGFR-expressing MCRC, refractory to irinotecan, pre-treated with both irinotecan and oxaliplatin with fluorouracil or capecitabine combinations, and PS 0–2, were included to receive cetuximab (400 mg/m2 week 1 and 250 mg/m2 weekly thereafter) plus irinotecan (180 mg/m2 every 2 weeks) until tumour progression or unacceptable toxicity. Pts were analysed weekly for toxicity and every 12 weeks for response. Recruitment is completed. Currently, 38 pts are evaluable for toxicity (2 pts recently recruited) and 23 pts for response (16 pts on treatment for <12 weeks and 1 pt withdrew at week 6 due to lung thromboembolism not related to study treatment). Results: M/F 24/14, median age 63 years (range: 33–78), colon/rectum 23/15, ECOG PS=0/1/2 9/23/6, Metastatic sites 1/2/>2 16/19/3 (Liver 43%, lung 23%, nodes 17%, pelvic 5%, others 12%). A total of 418 weekly infusions were administered (mean: 11; range: 3–37). Preliminary efficacy data is as follows: 3 PR, 3 SD, 17 PD with an overall response rate of 13% (95% CI: 3–34%) and disease control rate of 26% (95% CI: 10–48%). Major toxicities (G 1–2/G 3–4) were: Acne-like skin rash 58/11%, Anemia 32/3%, Neutropenia 16/13%, Nausea-vomiting 32/0%, Diarrhoea 32/11%. Median time to progression was 3.5 months (Range: 1–10+) and median overall survival was 7.3 months (Range: 1.5–12+). Conclusions: These preliminary results suggest that cetuximab and irinotecan combination, is a reasonably effective treatment for pts with highly pre-treated MCRC with an acceptable toxicity profile

No significant financial relationships to disclose.

Gemcitabine plus vinorelbine for the treatment of advanced non-small cell lung cancer

The aim of this study was to determine the clinical activity and toxicity of a novel chemotherapy regimen of weekly gemcitabine and vinorelbine in patients with advanced non-small cell lung cancer (NSCLC). 40 chemotherapy-naïve patients with stage IIIB/IV NSCLC were included. The doses of gemcitabine and vinorelbine were 1000 and 25 mg/m(2), respectively, given on days 1, 8 and 15, every 28 days. 38 patients were evaluable for response. One patient achieved a complete response (CR) and 10 attained a partial response (PR), for an overall response rate (ORR) of 29% (95% confidence interval (CI): 15-43%). 47% of patients experienced a clinical benefit. The main toxicity consisted of grade 3 anaemia and neutropenia in 5% of patients. Non-haematological toxicity was minimal. The dose-intensities were 744 mg/m(2)/week for gemcitabine and 15 mg/m(2)/week for vinorelbine. 40% of the patients survived for longer than 1 year. The median time to progression was 4 months and the median survival 8.5 months (95% CI: 3.1-13.8 months). The weekly administration of gemcitabine and vinorelbine is very well tolerated and results in an acceptable response rate for the treatment of NSCLC.