Impact of circulating tumor DNA mutant allele fraction on prognosis in RAS-mutant metastatic colorectal cancer

Immunotherapy: Constructive Approach for Breast Cancer Treatment

A novel and rapid therapeutic approach is the treatment of human breast cancer by enhancing the host's immune system. In initial findings, program death one (PD-1) and program cell death ligand one (PD-L1) showed positive results towards solid tumors, but tumor relapse and drug resistance are the major concerns. Breast cancer therapy has been transformed by the advent of immune checkpoint blockades (ICBs). Triple-negative breast cancers (TNBCs) have exhibited enduring responses to clinical usage of immune checkpoint inhibitors (ICBs) like atezolizumab and pembrolizumab. Nonetheless, a notable proportion of individuals with TNBC do not experience advantages from these treatments, and there is limited comprehension of the resistance mechanisms. Another approach to overcome resistance is cancer stem cells (CSCs), as these cells are crucial for the initiation and growth of tumors in the body. Various cancer vaccines are created using stem cells (dendritic, whole cell, bacterial) and focus primarily on targeting tumor-related antigens. The ultimate objective of cancer vaccines is to immunize the patients by active artificial immunity against cancer, though. In this review, we primarily focused on existing immunotherapeutic options, immune checkpoint blockers, the latest progress in understanding the molecular mechanisms underlying resistance to immune checkpoint inhibitors (ICBs), advanced strategies to overcome resistance to ICBs, cancer stem cell antigens and molecular markers, ongoing clinical trials for BCs and cancer vaccines for breast cancer.

Early changes in circulating tumor DNA (ctDNA) predict treatment response in metastatic KRAS-mutated colorectal cancer (mCRC) patients

The detection of RAS mutations and co-mutations in liquid biopsy offers a novel paradigm for the dynamic management of metastatic colorectal cancer (mCRC) patients. Expanding the results of the prospective OMITERC (OMIcs application from solid to liquid biopsy for a personalized ThERapy of Cancer) project, we collected blood samples at specific time points from patients who received a first-line chemotherapy (CT) for KRAS-mutated mCRC. CTC quantification was performed by CellSearch® system. Libraries from cfDNA were prepared using the Oncomine™ Colon cfDNA Assay to detect tumour-derived DNA in cfDNA. The analysis involved >240 hotspots in 14 genes. Twenty patients with KRAS-mutated mCRC treated at the Medical Oncology Unit of Careggi University Hospital were prospectively enrolled. Nine patients had available data for longitudinal monitoring of cfDNA. After 6 weeks of first-line CT an increase of KRAS-mutated clone was reported in the only patient who did not obtain disease control, while all patients with decrease of KRAS clones obtained disease control. Overall, in patients with a short (<9 months) progression-free survival (PFS) we registered, at 6 weeks, an increase in cfDNA levels and in KRAS mutations or other co-mutations, i.e. PIK3CA, FBXW7, GNAS, and TP53. In selected cases, co-mutations were able to better anticipate radiological progressive disease (PD) than the increase of KRAS-mutated clones. In conclusion, our study confirms plasma ctDNA as a crucial tool for anticipating PD at an early time point and highlights the value of a comprehensive assessment of clonal dynamics to improve the management of patients with mCRC.

The Clinical Significance of Circulating Tumor DNA for Minimal Residual Disease Identification in Early-Stage Non-Small Cell Lung Cancer

Lung cancer (LC) is the deadliest malignancy worldwide. In an operable stage I-III patient setting, the detection of minimal residual disease (MRD) after curative treatment could identify patients at higher risk of relapse. In this context, the study of circulating tumor DNA (ctDNA) is emerging as a useful tool to identify patients who could benefit from an adjuvant treatment, and patients who could avoid adverse events related to a more aggressive clinical management. On the other hand, ctDNA profiling presents technical, biological and standardization challenges before entering clinical practice as a decisional tool. In this paper, we review the latest advances regarding the role of ctDNA in identifying MRD and in predicting patients' prognosis, with a particular focus on clinical trials investigating the potential of ctDNA, the technical challenges to address and the biological parameters that influence the MRD detection.

Unravelling the Complexity of Colorectal Cancer: Heterogeneity, Clonal Evolution, and Clinical Implications

Colorectal cancer (CRC) is a global health concern and a leading cause of death worldwide. The disease's course and response to treatment are significantly influenced by its heterogeneity, both within a single lesion and between primary and metastatic sites. Biomarkers, such as mutations in KRAS, NRAS, and BRAF, provide valuable guidance for treatment decisions in patients with metastatic CRC. While high concordance exists between mutational status in primary and metastatic lesions, some heterogeneity may be present. Circulating tumor DNA (ctDNA) analysis has proven invaluable in identifying genetic heterogeneity and predicting prognosis in RAS-mutated metastatic CRC patients. Tumor heterogeneity can arise from genetic and non-genetic factors, affecting tumor development and response to therapy. To comprehend and address clonal evolution and intratumoral heterogeneity, comprehensive genomic studies employing techniques such as next-generation sequencing and computational analysis are essential. Liquid biopsy, notably through analysis of ctDNA, enables real-time clonal evolution and treatment response monitoring. However, challenges remain in standardizing procedures and accurately characterizing tumor subpopulations. Various models elucidate the origin of CRC heterogeneity, highlighting the intricate molecular pathways involved. This review focuses on intrapatient cancer heterogeneity and genetic clonal evolution in metastatic CRC, with an emphasis on clinical applications.

Circulating tumour DNA at baseline for individualised prognostication in patients with chemotherapy-naïve metastatic colorectal cancer. An AGEO prospective study

PURPOSE

Baseline circulating tumour DNA (ctDNA) is a potential prognostic marker in metastatic colorectal cancer (mCRC) patients. However, few studies have compared ctDNA with the usual prognostic factors, and no ctDNA cut-off has been proposed for daily use in clinical practice.

PATIENTS AND METHODS

Chemotherapy-naive patients with mCRC were prospectively included. Plasma samples were collected at diagnosis and analysed centrally by both NGS and methylation digital PCR. Baseline patient and disease characteristics, treatment regimens, and secondary surgeries were collected. The restricted cubic spline method was used to define the optimal cut-off of ctDNA mutated allelic frequency (MAF). Prognostic values were assessed on overall survival (OS) using Cox models.

RESULTS

From July 2015 to December 2016, 412 patients were included. ctDNA was undetectable in 83 patients (20%). ctDNA was an independent prognostic marker for OS considering the whole study population. The optimal cut-off for ctDNA MAF was 20% with median OS of 16.0 and 35.8 months for patients with MAF ≥20% and<20%, respectively (hazard ratio = 0.40; 95% confidence intervals: 0.31-0.51; P < 0.0001). The independent prognostic value of ctDNA MAF at 20% was confirmed in subgroups defined by RAS/BRAF status or resectability of metastases. Combining ctDNA MAF and carcinoembryonic antigen levels allowed us to define three different prognostic groups with median OS of 14.2, 21.1, and 46.4 months (P < 0.0001).

CONCLUSION

ctDNA with a MAF cut-off of 20% improves prognostication of chemotherapy-naïve mCRC patients and may be useful in the future for individualised therapeutic decisions and as a stratification factor in clinical trials.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT02502656.

Potential unreliability of ALK variant allele frequency in the efficacy prediction of targeted therapy in NSCLC

Anaplastic lymphoma kinase (ALK) is the most common fusion gene involved in non-small cell lung cancer (NSCLC), and remarkable response has been achieved with the use of ALK tyrosine kinase inhibitors (ALK-TKIs). However, the clinical efficacy is highly variable. Pre-existing intratumoral heterogeneity (ITH) has been proven to contribute to the poor treatment response and the resistance to targeted therapies. In this work, we investigated whether the variant allele frequencies (VAFs) of ALK fusions can help assess ITH and predict targeted therapy efficacy. Through the application of next-generation sequencing (NGS), 7.2% (326/4548) of patients were detected to be ALK positive. On the basis of the adjusted VAF (adjVAF, VAF normalization for tumor purity) of four different threshold values (adjVAF < 50%, 40%, 30%, or 20%), the association of ALK subclonality with crizotinib efficacy was assessed. Nonetheless, no statistical association was observed between median progression-free survival (PFS) and ALK subclonality assessed by adjVAF, and a poor correlation of adjVAF with PFS was found among the 85 patients who received first-line crizotinib. Results suggest that the ALK VAF determined by hybrid capture-based NGS is probably unreliable for ITH assessment and targeted therapy efficacy prediction in NSCLC.

Liver transplantation in metastatic colorectal cancer: are we ready for it?

Colorectal cancer (CRC) is a prevalent disease worldwide, with more than 50% of patients developing metastases to the liver. Five-year overall survival remains modest among patients with metastatic CRC (mCRC) treated with conventional therapies however, liver transplantation in a highly selected population can improve clinical outcomes with an impressive 5-year overall survival of 83%. Despite liver transplantation appearing to be a promising therapeutical option for well-selected patients with mCRC with the liver-limited disease, these data come from small monocentric trials which included a heterogeneous population. Currently, several clinical trials are evaluating liver transplantation in this scenario, aiming for a more accurate patient selection by integrating liquid biopsy, tissue profiling, and nuclear medicine to the already known clinical biomarkers that eventually may lead to a survival improvement. In this paper, the clinical outcomes and inclusion criteria from the most relevant clinical trials and clinical series involving liver transplantation in patients with liver-limited disease colorectal cancer are reviewed as well as the trials currently recruiting.

Next-generation sequencing (NGS) profiling of matched tumor and circulating tumor DNA (ctDNA) in head and neck squamous cell carcinoma (HNSCC)

OBJECTIVES

The aim of this pilot study was to evaluate the presence of somatic mutations in matched tumor and circulating DNA (ctDNA) samples from patients with primary head and neck squamous cell carcinoma (HNSCC) and assess the association of changes in ctDNA levels with survival.

MATERIALS AND METHODS

Our study included 62 patients with stage I-IVB HNSCC treated with surgery or radical chemoradiotherapy with curative intent. Plasma samples were obtained at baseline, at the end of treatment (EOT), and at disease progression. Tumor DNA was extracted from plasma (ctDNA) and tumor tissue (tDNA). The Safe Sequencing System was used assess the presence of pathogenic variants in four genes (TP53, CDKN2A, HRAS and PI3KCA) in both ctDNA and tDNA.

RESULTS

Forty-five patients had available tissue and plasma samples. Concordance of genotyping results between tDNA and ctDNA at baseline was 53.3%. TP53 mutations were most commonly identified at baseline in both ctDNA (32.6%) and tDNA (40%). The presence of mutations in this restricted set of 4 genes in tissue samples at baseline was associated with decreased overall survival (OS) [median 58.3 months for patients with mutations vs. 89 months for patients without mutations, p < 0.013]. Similarly, patients presenting with mutations in ctDNA had shorter OS [median 53.8 vs. 78.6 months, p < 0.037]. CtDNA clearance at EOT did not show any association with PFS or OS.

CONCLUSIONS

Liquid biopsy enables real-time molecular characterization of HNSCC and might predict survival. Larger studies are needed to validate the utility of ctDNA as a biomarker in HNSCC.

Liquid Biopsy Detects Early Molecular Response and Predicts Benefit to First-Line Chemotherapy plus Cetuximab in Metastatic Colorectal Cancer: PLATFORM-B Study

PURPOSE

Chemotherapy plus anti-EGFR is standard first-line therapy in RAS wild-type (wt) metastatic colorectal cancer (mCRC), but biomarkers of early response are clinically needed. We aimed to define the utility of ctDNA to assess early response in patients with mCRC receiving first-line anti-EGFR therapy.

EXPERIMENTAL DESIGN

Prospective multicentric study of tissue patients with RAS wt mCRC treated with first-line chemotherapy plus cetuximab undergoing sequential liquid biopsies. Baseline and early (C3) ctDNA were analyzed by NGS. Trunk mutations were assessed as surrogate marker of total tumor burden. RAS/BRAF/MEK/EGFR-ECD were considered mutations of resistance. ctDNA results were correlated with clinical outcome.

RESULTS

One hundred patients were included. ctDNA was detected in 72% of patients at baseline and 34% at C3. Decrease in ctDNA trunk mutations correlated with progression-free survival (PFS; HR, 0.23; P = 0.001). RAS/BRAF were the only resistant mutations detected at C3. An increase in the relative fraction of RAS/BRAF at C3 was followed by an expansion of the RAS clone until PD, and was associated with shorter PFS (HR, 10.5; P < 0.001). The best predictor of response was the combined analysis of trunk and resistant mutations at C3. Accordingly, patients with "early molecular response" (decrease in trunk and decrease in resistant mutations) had better response (77.5% vs. 25%, P = 0.008) and longer PFS (HR, 0.18; P < 0.001) compared with patients with "early molecular progression" (increase in trunk and/or increase in resistant mutations).

CONCLUSIONS

ctDNA detects early molecular response and predicts benefit to chemotherapy plus cetuximab. A comprehensive NGS-based approach is recommended to integrate information on total disease burden and resistant mutations. See related commentary by Eluri et al., p. 302.

Shaping the Future of Immunotherapy Targets and Biomarkers in Melanoma and Non-Melanoma Cutaneous Cancers

Recent advances in treating cutaneous melanoma have resulted in impressive patient survival gains. Refinement of disease staging and accurate patient risk classification have significantly improved our prognostic knowledge and ability to accurately stratify treatment. Undoubtedly, the most important step towards optimizing patient outcomes has been the advent of cancer immunotherapy, in the form of immune checkpoint inhibition (ICI). Immunotherapy has established its cardinal role in the management of both early and late-stage melanoma. Through leveraging outcomes in melanoma, immunotherapy has also extended its benefit to other types of skin cancers. In this review, we endeavor to summarize the current role of immunotherapy in melanoma and non-melanoma skin cancers, highlight the most pertinent immunotherapy-related molecular biomarkers, and lastly, shed light on future research directions.

A phase II study to explore biomarkers for the use of mFOLFOX6/XELOX plus bevacizumab as a first-line chemotherapy in patients with metastatic colorectal cancer (WJOG7612GTR)

BACKGROUND

The purpose of this prospective study was to assess the ability of plasma vascular endothelial growth factor-A short isoforms (pVEGF-Asi) to predict bevacizumab (BV) efficacy and to explore other circulating biomarkers in metastatic colorectal cancer (mCRC) patients treated with modified FOLFOX6/XELOX plus BV (mFOLFOX6/XELOX + BV).

PATIENTS AND METHODS

Pre-treatment plasma samples were collected from 100 mCRC patients receiving first-line chemotherapy with mFOLFOX6/XELOX + BV. The plasma levels of 11 angiogenesis-associated molecules, including pVEGF-Asi and 22 cancer-associated gene mutations in circulating tumor DNA, were analyzed. For the primary endpoint, we assumed that the hazard ratio (HR) for progression-free survival (PFS) calculated using a Cox proportional hazards model was <1.15, comparing patients with a high versus those with a low pVEGF-Asi level divided according to the median pVEGF-Asi value.

RESULTS

The median value of pVEGF-Asi was 37 (range 6.5-262) pg/ml. The HR for PFS between the high and low pVEGF-Asi patient groups was 1.3 [95% confidence interval (CI) 0.8-2.1; log rank, P = 0.25], which was larger than the predefined threshold of 1.15. The multivariate analysis demonstrated that PFS was significantly associated with plasma intercellular adhesion molecule-1 (pICAM-1) (≥190.0 versus <190.0 ng/ml; HR 2.1; 95% CI 1.3-3.5), RAS (mutant versus wild; HR 2.5; 95% CI 1.5-4.3), and FBXW7 (mutant versus wild; HR 2.8; 95% CI 1.2-6.8), whereas overall survival was significantly associated with pICAM-1 (HR 2.0; 95% CI 1.1-3.7) and RAS (HR 2.6; 95% CI 1.5-4.6).

CONCLUSIONS

The addition of BV was unable to compensate for the poor PFS associated with a high pVEGF-Asi level, suggesting that pVEGF-Asi is unlikely to be a good predictive biomarker of the efficacy of mFOLFOX6/XELOX + BV therapy. The clinical significance of circulating ICAM-1, mutant RAS, and mutant FBXW7 levels should be studied further.

Circulating tumour DNA and its clinical utility in predicting treatment response or survival in patients with metastatic colorectal cancer: a systematic review and meta-analysis

BACKGROUND

We investigate the current knowledge on circulating tumour DNA (ctDNA) and its clinical utility in predicting outcomes in patients with metastatic colorectal cancer (mCRC).

METHODS

PubMed, Embase, Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Trials were searched. Last search 16/12/2020. We included studies on patients with mCRC reporting the predictive or prognostic value of ctDNA. We performed separate random-effects meta-analyses to investigate if baseline ctDNA and early changes in ctDNA levels during treatment were associated with survival. The risk of bias was assessed according to the Quality in Prognosis Studies tool.

RESULTS

Seventy-one studies were included with 6930 patients. Twenty-four studies were included in meta-analyses. High baseline ctDNA level was associated with short progression-free survival (PFS) (HR = 2.2; 95% CI 1.8-2.8; n = 509) and overall survival (OS) (HR = 2.4; 95% CI 1.9-3.1; n = 1336). A small or no early decrease in ctDNA levels during treatment was associated with short PFS (HR = 3.0; 95% CI 2.2-4.2; n = 479) and OS (HR = 2.8; 95% CI 2.1-3.9; n = 583). Results on clonal evolution and lead-time were inconsistent. A majority of included studies (n = 50/71) had high risk of bias in at least one domain.

CONCLUSIONS

Plasma ctDNA is a strong prognostic biomarker in mCRC. However, true clinical utility is lacking.

Encorafenib plus cetuximab with or without binimetinib in patients with BRAF V600E-mutated metastatic colorectal cancer: real-life data from an Italian multicenter experience

Background

Encorafenib plus cetuximab with or without binimetinib showed increased objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) compared with chemotherapy plus anti-EGFR in previously treated patients with BRAF V600E-mutated (mut) metastatic colorectal cancer (mCRC). Although no formal comparison was planned, addition of binimetinib to encorafenib plus cetuximab did not provide significant efficacy advantage.

Patients and methods

This real-life study was aimed at evaluating safety, activity, and efficacy of encorafenib plus cetuximab with or without binimetinib in patients with BRAF V600E-mut mCRC treated at 21 Italian centers within a nominal use program launched in May 2019.

Results

Out of 133 patients included, 97 (73%) received encorafenib plus cetuximab (targeted doublet) and 36 (27%) the same therapy plus binimetinib (targeted triplet). Most patients had Eastern Cooperative Group Performance Status (ECOG-PS) of 0 or 1 (86%), right-sided primary tumor (69%), and synchronous disease (66%). Twenty (15%) tumors were DNA mismatch repair deficiency (dMMR)/microsatellite instability (MSI)-high. As many as 44 (34%) patients had received two or more prior lines of therapy, 122 (92%) were previously exposed to oxaliplatin, and 109 (82%) to anti-vascular endothelial growth factor (anti-VEGF). Most frequent adverse events were asthenia (62%) and anti-EGFR-related skin rash (52%). Any grade nausea (P = 0.03), vomiting (P = 0.04), and diarrhea (P = 0.07) were more frequent with the triplet therapy, while melanocytic nevi were less common (P = 0.06). Overall, ORR and disease control rate (DCR) were 23% and 69%, respectively, with numerically higher rates in the triplet group (ORR 31% versus 17%, P = 0.12; DCR 78% versus 65%, P = 0.23). Median PFS and OS were 4.5 and 7.2 months, respectively. Worse ECOG-PS, peritoneal metastases, and more than one prior treatment were independent poor prognostic factors for PFS and OS. Clonality of BRAF mutation measured as adjusted mutant allele fraction in tumor tissue was not associated with clinical outcome.

Conclusions

Our real-life data are consistent with those from the BEACON trial in terms of safety, activity, and efficacy. Patients in good general condition and not heavily pretreated are those more likely to derive benefit from the targeted treatment.

•

Encorafenib plus cetuximab ± binimetinib is safe and effective for BRAF V600E mut mCRC even in the real-world setting.

•

Median OS is slightly shorter than in the BEACON trial, probably due to less selected patients in real life.

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Patients deriving more benefit from targeted therapy are likely those in good general conditions and not heavily pretreated.

•

BRAF adjusted MAF is worth further investigation to better characterize the genomic heterogeneity of BRAF V600E mut mCRC.

Driver Mutation Variant Allele Frequency in Circulating Tumor DNA and Association with Clinical Outcome in Patients with Non-Small Cell Lung Cancer and EGFR- and KRAS-Mutated Tumors

Clinical implementation of mutational analysis for next-generation sequencing-based assays has largely been of a binary nature, with pathogenic mutations being reported as either positive or negative. Actionability on the continuous output of variant allele frequency (VAF) has not been well characterized in the clinical setting, thus limiting its use. In this study, analytical validity and performance of the short variant VAF based on a next-generation sequencing-based liquid biopsy assay, FoundationOne Liquid CDx, were evaluated through assessment of precision, analytical accuracy, limit of blank, and limit of detection. Analytical validation of VAF values measured by using FoundationOne Liquid CDx supports that these values are accurate, precise, robust, and linear with the true VAF value. The association of allele frequency of clinically relevant short variants in circulating-free DNA and the association with overall survival for patients using real-world data were also assessed. The results of the association analysis indicate that VAF of the predictive biomarker mutation negatively correlates with overall survival of patients with non-small cell lung cancer.

Longitudinal Circulating Tumor DNA Profiling in Metastatic Colorectal Cancer During Anti-EGFR Therapy

Background

Metastatic colorectal cancer (mCRC) is a heterogenous disease with limited precision medicine and targeted therapy options. Monoclonal antibodies against epidermal growth factor receptor (EGFR) have been a crucial treatment option for mCRC. However, proper biomarkers for predicting therapeutic response remain unknown. As a non-invasive test, circulating tumor DNA (ctDNA) is appropriately positioned to reveal tumor heterogeneity and evolution, as it can be used in real-time genomic profiling. To evaluate the significance of ctDNA in monitoring the dynamic therapeutic response and prognosis of mCRC, we detected the baseline and dynamic changes of ctDNA in mCRC patients receiving anti-EGFR therapies.

Methods

A single-center study was conducted retrospectively. Plasma samples from mCRC patients who received anti-EGFR therapies were collected at baseline and continuous treatment points. The ctDNA was extracted and sequenced with a target panel of tumor-related genes via next-generation sequencing (NGS). Clinical information was also collected and analyzed.

Results

We conducted dynamic sampling of 22 mCRC patients, analyzed 130 plasma samples, obtained a baseline genomic mutation profile of the patients. In total, 54 variations were detected in 22 plasma samples, with a positive rate of 77.3% (17/22). TP53 was the most mutated gene (59.1%, 13/22), followed by APC (18.2%, 4/22). There was a high concordance rate of genomic characteristics between the tumor tissue test by polymerase chain reaction and ctDNA test by NGS. The mutation discrepancy increased with an extended course of treatment. During remission TP53 and APC were the most frequently decreased clonal mutations and KRAS, NRAS, ERBB2 and PIK3CA were the most decreased subclonal mutations. Both mutation types were increased during progression. The ctDNA decreased earlier than did the responses of computed tomography and traditional tumor markers (carbohydrate antigen 19-9 and carcinoembryonic antigen [CEA]). Lactate dehydrogenase level (P = 0.041), CEA level (P = 0.038), and primary lesion site (P = 0.038) were independent risk factors that influenced overall survival. Moreover, patients with RAS mutations tended to have a worse prognosis (P = 0.072).

Conclusions

This study demonstrates that ctDNA is a promising biomarker for monitoring the dynamic response to treatment and determining the prognosis of mCRC.

Variant allele frequency in baseline circulating tumour DNA to measure tumour burden and to stratify outcomes in patients with RAS wild-type metastatic colorectal cancer: a translational objective of the Valentino study

INTRODUCTION

In patients with metastatic colorectal cancer (mCRC), baseline circulating tumour DNA (ctDNA) variant allele fraction (VAF) might serve as a surrogate of disease burden and should be evaluated in comparison with CEA and RECIST-defined sum of target lesions.

METHODS

In this pre-planned analysis of the VALENTINO trial, we included patients with RAS wild-type mCRC receiving upfront FOLFOX/panitumumab with available baseline liquid biopsy. CtDNA was analysed by means of a 14-gene NGS panel. For each patient, the gene with the highest VAF in ctDNA was selected.

RESULTS

The final cohort included 135 patients. The median VAF was 12.6% (IQR: 2.0-45.2%). Higher VAF was observed in patients with liver metastases and with synchronous metastases presentation. Patients with high VAF had poorer median OS compared to those with low VAF (21.8 vs 36.5 months; HR: 1.82, 95%CI: 1.20-2.76; p = 0.005). VAF outperformed baseline CEA and target lesion diameter in the prognostic stratification and remained significantly correlated with OS (p = 0.003) in a multivariate model. VAF was not significantly correlated with dimensional response and PFS.

CONCLUSION

CtDNA measured by VAF is prognostic in patients with RAS wild-type mCRC. Response and PFS after an anti-EGFR-based first-line strategy are independent from initial tumour burden.

Monitoring and adapting cancer treatment using circulating tumor DNA kinetics: Current research, opportunities, and challenges

Circulating tumor DNA (ctDNA) has emerged as a biomarker with wide-ranging applications in cancer management. While its role in guiding precision medicine in certain tumors via noninvasive detection of susceptibility and resistance alterations is now well established, recent evidence has pointed to more generalizable use in treatment monitoring. Quantitative changes in ctDNA levels over time (i.e., ctDNA kinetics) have shown potential as an early indicator of therapeutic efficacy and could enable treatment adaptation. However, ctDNA kinetics are complex and heterogeneous, affected by tumor biology, host physiology, and treatment factors. This review outlines the current preclinical and clinical knowledge of ctDNA kinetics in cancer and how early on-treatment changes in ctDNA levels could be applied in clinical research to collect evidence to support implementation in daily practice.

Development and Validation of a Targeted ‘Liquid’ NGS Panel for Treatment Customization in Patients with Metastatic Colorectal Cancer

The detection of actionable mutations in tumor tissue is a prerequisite for treatment customization in patients with metastatic colorectal cancer (mCRC). Analysis of circulating tumor DNA (ctDNA) for the identification of such mutations in patients’ plasma is an attractive alternative to invasive tissue biopsies. Despite having the high analytical sensitivity required for ctDNA analysis, digital polymerase chain reaction (dPCR) technologies can only detect a very limited number of hotspot mutations, whilst a broader mutation panel is currently needed for clinical decision making. Recent advances in next-generation sequencing (NGS) have led to high-sensitivity platforms that allow screening of multiple genes at a single assay. Our goal was to develop a small, cost- and time-effective NGS gene panel that could be easily integrated in the day-to-day clinical routine in the management of patients with mCRC. We designed a targeted panel comprising hotspots in six clinically relevant genes (KRAS, NRAS, MET, BRAF, ERBB2 and EGFR) and validated it in a total of 68 samples from 30 patients at diagnosis, first and second disease progression. Results from our NGS panel were compared against plasma testing with BEAMing dPCR regarding the RAS gene status. The overall percent of agreement was 83.6%, with a positive and negative percent agreement of 74.3% and 96.2%, respectively. Further comparison of plasma NGS with standard tissue testing used in the clinic showed an overall percent agreement of 86.7% for RAS status, with a positive and negative percent agreement of 81.2% and 92.8%, respectively. Thus, our study strongly supports the validity and efficiency of an affordable targeted NGS panel for the detection of clinically relevant mutations in patients with mCRC.

Upfront primary tumour resection and survival in synchronous metastatic colorectal cancer according to primary tumour location and RAS status: Pooled analysis of the Spanish Cooperative Group for the Treatment of Digestive Tumours (TTD)

INTRODUCTION

Retrospective studies and meta-analyses suggest that upfront primary tumour resection (UPTR) confers a survival benefit in patients with asymptomatic unresectable metastatic colorectal cancer (mCRC) undergoing chemotherapy, however a consensus of its role in routine clinical practice in the current era of targeted therapies is lacking. This retrospective study aimed to analyse the survival benefit of UPTR in terms of tumour location and mutational status, in patients with synchronous mCRC receiving chemotherapy and targeted therapy.

PATIENTS AND METHODS

Survival was analysed in a pooled cohort of synchronous mCRC patients treated with a first-line anti-VEGF or anti-EGFR inhibitor in seven trials of the Spanish TTD group, according to UPTR, tumour-sidedness and mutational profiling.

RESULTS

Of 1334 eligible patients, 642 (48%) had undergone UPTR. UPTR was associated with significantly longer overall survival (OS; 25.0 vs 20.3 months; HR 1.30, 95%CI 1.15-1.48; p < 0.0001). UPTR was associated with significant OS benefit in both left-sided (HR 1.38, 95%CI 1.13-1.69; p = 0.002) and right-sided (HR 1.39, 95%CI 1.00-1.94; p = 0.049) tumours, RASwt (HR 1.29, 95%CI 1.05-1.60; p = 0.016) and BRAFwt (HR 1.49, 95%CI 1.21-1.84; p = 0.0002) tumours, and treatment with anti-EGFRs (HR 1.47, 95%CI 1.13-1.92; p = 0.004) and anti-VEGFs (HR 1.25, 95%CI 1.08-1.44; p = 0.003). Multivariate analysis identified number of metastatic sites, RAS status, primary tumour location and UPTR as independent prognostic factors for OS.

CONCLUSION

Considering the selection bias inherent to this study, our results support UPTR before first-line anti-EGFR or anti-VEGF targeted therapy in right and left-sided asymptomatic unresectable synchronous mCRC patients. RAS/BRAF mutational status may also influence UPTR function.

A Real-World Application of Liquid Biopsy in Metastatic Colorectal Cancer: The Poseidon Study

BACKGROUND

First-line decision making is the key to the successful care of mCRC patients and RAS/BRAF status is crucial to select the best targeted agent. In hub centers, a relevant proportion of patients referred from small volume centers may not have standard tissue-based (STB) molecular results available at the time of the first visit (T0). Liquid biopsy (LB) may help circumvent these hurdles.

METHODS

A monoinstitutional prospective head-to-head comparison of LB versus (vs.) STB testing was performed in a real-world setting. Selection criteria included: mCRC diagnosis with unknown RAS/BRAF status at T0, tumoral tissue archived in external centers, no previous treatment with anti-EGFR. At T0, patients underwent plasma sampling for LB testing and procedure for tissue recovery. RAS/BRAF genotyping was carried out by droplet digital PCR on circulating-tumoral (ct) DNA. The primary endpoint was the comparison of time to LB (T1) vs. STB (T2) results using the Mann-Whitney U test. Secondary endpoints were the concordance between LB and STB defined as overall percent agreement and the accuracy of LB in terms of specificity, sensitivity, positive and negative predictive value. We also performed an exploratory analysis on urinary (u) ctDNA.

RESULTS

A total of 33 mCRC patients were included. Mean T1 and T2 was 7 and 22 days (d), respectively (p < 0.00001). T2 included a mean time for archival tissue recovery of 17 d. The overall percent agreement between LB and STB analysis was 83%. Compared to STB testing, LB specificity and sensitivity were 90% and 80%, respectively, with a positive predictive value of 94% and negative one of 69%. In detail, at STB and LB testing, RAS mutation was found in 45% and 42% of patients, respectively; BRAF mutation in 15%. LB results included one false positive and four false negative. False negative cases showed a significantly lower tumor burden at basal CT scan. Concordance between STB and uctDNA testing was 89%.

CONCLUSIONS

Faster turnaround time, high concordance and accuracy are three key points supporting the adoption of LB in routinary mCRC care, in particular when decision on first-line therapy is urgent and tissue recovery from external centers may require a long time. Results should be interpreted with caution in LB wild-type cases with low tumor burden.

Clinical Applications of Minimal Residual Disease Assessments by Tumor-Informed and Tumor-Uninformed Circulating Tumor DNA in Colorectal Cancer

Simple Summary

Circulating tumor DNA, or ctDNA, are fragments of tumor DNA that can be detected in the blood of patients with colorectal cancer. Measuring ctDNA levels in the blood has shown the potential to provide important information that can be helpful in the clinical care of patients with colorectal cancer. For example, in patients with colon cancer that has been removed by surgery, measuring ctDNA in the blood can predict the likelihood of cancer recurrence, while in those with metastatic colorectal cancer, measuring ctDNA can inform the clinician whether chemotherapy is effective at earlier timepoints than currently available tests. In this review, we discuss the results from ongoing studies describing the utility of ctDNA measurements across all stages of colorectal cancer. We also discuss the various clinical scenarios that ctDNA may have the most immediate impact in colorectal cancer management.

Abstract

Emerging data suggest that circulating tumor DNA (ctDNA) can detect colorectal cancer (CRC)-specific signals across both non-metastatic and metastatic settings. With the development of multiple platforms, including tumor-informed and tumor-agnostic ctDNA assays and demonstration of their provocative analytic performance to detect minimal residual disease, there are now ongoing, phase III randomized clinical trials to evaluate their role in the management paradigm of CRC. In this review, we highlight landmark studies that have formed the basis for ongoing studies on the clinically applicability of plasma ctDNA assays in resected, stage I–III CRC and metastatic CRC. We discuss clinical settings by which ctDNA may have the most immediate impact in routine clinical practice. These include the potential for ctDNA to (1) guide surveillance and intensification or de-intensification strategies of adjuvant therapy in resected, stage I–III CRC, (2) predict treatment response to neoadjuvant therapy in locally advanced rectal cancer inclusive of total neoadjuvant therapy (TNT), and (3) predict response to systemic and surgical therapies in metastatic disease. We end by considering clinical variables that can influence our ability to reliably interpret ctDNA dynamics in the clinic.

LungBEAM: A prospective multicenter study to monitor stage IV NSCLC patients with EGFR mutations using BEAMing technology

OBJECTIVES

The aim of LungBEAM was to determine the value of a novel epidermal growth factor receptor (EGFR) mutation test in blood based on BEAMing technology to predict disease progression in advanced non-small cell lung cancer (NSCLC) patients treated with first- or second-generation EGFR-tyrosine kinase inhibitors (EGFR-TKIs). Another goal was to monitor the dynamics of EGFR mutations, as well as to track EGFR exon 20 p.T790M (p.T790M) resistance during treatment, as critical indicators of therapeutic efficacy and patient survival.

METHODS

Stage IV NSCLC patients with locally confirmed EGFR-TKI sensitizing mutations (ex19del and/or L858R) in biopsy tissue who were candidates to receive first- or second-generation EGFR-TKI as first-line therapy were included. Plasma samples were obtained at baseline and every 4 weeks during treatment until a progression-free survival (PFS) event or until study completion (72-week follow-up). The mutant allele fraction (MAF) was determined for each identified mutation using BEAMing.

RESULTS

A total of 68 of the 110 (61.8%) patients experienced a PFS event. Twenty-six patients (23.6%) presented with an emergent p.T790M mutation in plasma at some point during follow-up, preceding radiologic progression with a median of 76 (interquartile ratio: 54-111) days. Disease progression correlated with the appearance of p.T790M in plasma with a hazard ratio (HR) of 1.94 (95% confidence interval [CI], 1.48-2.54; p < 0.001). The HR for progression in patients showing increasing plasma sensitizing mutation levels (positive MAF slope) versus patients showing either decreasing or unchanged plasma mutation levels (negative or null MAF slopes) was 3.85 (95% CI, 2.01-7.36; p < 0.001).

CONCLUSION

Detection and quantification of EGFR mutations in circulating tumor DNA using the highly sensitive BEAMing method should greatly assist in optimizing treatment decisions for advanced NSCLC patients.

Macrophages, as a Promising Strategy to Targeted Treatment for Colorectal Cancer Metastasis in Tumor Immune Microenvironment

The tumor immune microenvironment plays a vital role in the metastasis of colorectal cancer. As one of the most important immune cells, macrophages act as phagocytes, patrol the surroundings of tissues, and remove invading pathogens and cell debris to maintain tissue homeostasis. Significantly, macrophages have a characteristic of high plasticity and can be classified into different subtypes according to the different functions, which can undergo reciprocal phenotypic switching induced by different types of molecules and signaling pathways. Macrophages regulate the development and metastatic potential of colorectal cancer by changing the tumor immune microenvironment. In tumor tissues, the tumor-associated macrophages usually play a tumor-promoting role in the tumor immune microenvironment, and they are also associated with poor prognosis. This paper reviews the mechanisms and stimulating factors of macrophages in the process of colorectal cancer metastasis and intends to indicate that targeting macrophages may be a promising strategy in colorectal cancer treatment.

Personalized Therapy and Liquid Biopsy-A Focus on Colorectal Cancer

(1) Background: Resistance mechanisms represent a barrier to anti-cancer therapies. Liquid biopsies would allow obtaining additional information in order to develop targeted therapies to thwart the resistance phenomena but also to follow in time real response to treatment and be able to adapt it the most quickly possible way in case of resistance. (2) Methods: herein we summarize the different liquid biopsies which are currently under research; we then review the literature and focalize on one of their potential roles: the theranostic one and especially in the cases of colorectal cancers. (3) Results: few studies targeting liquid biopsy as a potential tool to adapt cancer treatments are present in the literature and encompass few patients. (4) Conclusions: further research is needed to prove the efficiency of LB. Indeed, it seems a promising tool to guide treatment by targeting actionable mutations with detection of resistant mutations.

Circulating Tumor DNA as a Biomarker for Outcomes Prediction in Colorectal Cancer Patients

Circulating tumour DNA (ctDNA) is a novel tool that has been investigated in several types of tumours, including colorectal cancer (CRC). In fact, the techniques based on liquid biopsies are proposed as appealing non-invasive alternatives to tissue biopsy, adding more insights into tumour molecular profile, heterogeneity and for cancer detection and monitoring. Additionally, some analysis showed that in CRC patients, ctDNA seems to act as a biomarker able to predict the outcome (prognostic role) and the response to treatments (predictive role). In particular, in the early stage CRC (stage I-III), it could represent a time marker of adjuvant therapy as well as a marker of minimal residual disease and recurrence risk in addition to the already recognized risk factors. In metastatic CRC, the analysis of molecular tumour profile by ctDNA has shown to have high concordance with the tissue biopsy at diagnosis. Additionally, some studies demonstrated that ctDNA level during the treatment was linked with the early response to treatment and prognosis. Finally, the quantitative analysis of ctDNA and copy number alterations may be useful in order to detect resistance to therapy at the time of progression of disease and to help in finding new therapeutic targets.

Clinicopathological factors associated with tumour-specific mutation detection in plasma of patients with RAS-mutated or BRAF-mutated metastatic colorectal cancer

Detection of tumour-specific circulating cell-free DNA in plasma (ctDNA) fails in a significant number of cases depending on the clinical context. The primary aim was to investigate clinicopathological factors associated with detection of ctDNA in patients with RAS-/BRAF-mutated metastatic colorectal cancer (mCRC) prior to first-line therapy. A secondary aim was to evaluate the prognostic impact of ctDNA compared to other biomarkers. Patients were included from the NORDIC-VII study (N = 253). ctDNA was sampled prior to treatment and analysed for hotspot tissue mutations (KRAS, NRAS, and BRAF) using droplet digital PCR. Multivariable regression models were constructed to predict the probability of mutation detection and survival. Increasing radiological size of target lesions by increments of 1 cm (odds ratio [OR] = 1.18; 95% confidence interval [CI] 1.09-1.27; P < .001), intact primary tumour (OR = 3.17; 95% CI 1.22-8.22; P = .018) and more than one metastatic site (OR = 3.08; 95% CI 1.32-7.19; P = .009) were associated with mutation detection in plasma. Metastatic involvement of the lung was associated with non-detection (OR = 0.26; 95% CI 0.12-0.58; P = .001). Preanalytical and analytical factors modulated detection. High allele frequencies of ctDNA indicated poor prognosis independently of CEA and CA19-9 (hazard ratio [HR] = 2.38; 95% CI 1.74-3.26; P < .001; N = 206). Clinicopathological characteristics should be carefully considered when evaluating ctDNA results from mCRC patients, especially when confronted with a plasma negative result. ctDNA may prove to be a clinically useful marker in the evaluation of mCRC treatment.

Analysis of circulating tumour DNA to identify patients with epidermal growth factor receptor-positive non-small cell lung cancer who might benefit from sequential tyrosine kinase inhibitor treatment

BACKGROUND

Survival data support the use of first-line osimertinib as the standard of care for epidermal growth factor receptor (EGFR)-positive non-small cell lung cancer (NSCLC). However, it remains unclear whether upfront osimertinib is superior to sequential first- or second-generation tyrosine kinase inhibitors (TKIs) followed by osimertinib for all patients. It is impossible to predict which patients are at high risk of progression, and this constitutes a major limitation of the sequential TKI approach.

PATIENTS AND METHODS

A total of 830 plasma samples from 228 patients with stage IV, EGFR-positive NSCLC who were treated with first-line TKIs were analysed by digital polymerase chain reaction (dPCR).

RESULTS

The circulating tumour DNA (ctDNA) levels helped to identify patients with significantly improved survival rate, regardless of the treatment. Patients treated with first- or second-generation TKIs (N = 189) with EGFR mutations in plasma at a mutant allele frequency (MAF) <7% before treatment initiation (low-risk patients) or who were ctDNA negative after 3 or 6 months of treatment and with an MAF <7% at diagnosis (high responders) had two-thirds lower risk of death than patients in the opposite situation (adjusted hazard ratio [HR] = 0.38; 95% confidence interval [CI]: 0.23-0.64 and HR = 0.22; 95% CI: 0.12-0.42, respectively). The median overall survival (OS) for low-risk patients and high responders treated with first- or second-generation TKIs was 34.2 months and not reached, respectively, regardless of second-line treatment. There were no significant difference in OS between low-risk or high-responder patients treated upfront with osimertinib (N = 39) and those treated under a sequential approach with osimertinib (N = 60). Median OS was not reached in both cases.

CONCLUSIONS

Pre-treatment ctDNA levels identify low-risk patients, who may benefit from sequential TKI treatment. Information regarding EGFR mutation clearance can help to improve patient selection.

Combined Analysis of Concordance between Liquid and Tumor Tissue Biopsies for RAS Mutations in Colorectal Cancer with a Single Metastasis Site: The METABEAM Study

PURPOSE

OncoBEAM™ is a circulating tumor DNA (ctDNA) test that uses the BEAMing digital PCR technology. We clarified the association between the baseline tumor burden and discordance in the RAS status by metastatic sites in patients with a single metastatic site.

EXPERIMENTAL DESIGN

Data from previous Spanish and Japanese studies investigating the concordance of the RAS status between OncoBEAM™ and tissue biopsy in 221 patients with metastatic colorectal cancer (mCRC) were used. We collected data from patients with liver, peritoneal, or lung metastases and evaluated the concordance rates according to the metastatic site and the association between the concordance rate and tumor burden.

RESULTS

Patients had metastases in the liver (n = 151), peritoneum (n = 25), or lung (n = 45) with concordance rates of 91% (95% confidence interval, 85%-95%), 88% (68%-97%), and 64% (49%-78%), respectively. Factors associated with concordance included the baseline longest diameter and lesion number (P = 0.004), and sample collection interval (P = 0.036). Concordance rates ≥90% were observed in the following groups: liver metastases alone, regardless of the baseline longest diameter and lesion number; peritoneal metastases alone in patients with a baseline longest diameter ≥20 mm; and lung metastases alone in patients with a baseline longest diameter ≥20 mm and/or number of lesions ≥10.

CONCLUSIONS

Plasma ctDNA-based liquid biopsy in patients with mCRC may be useful depending on the metastatic site. The maximum diameter and lesion number should be carefully considered when determining patients' RAS status with only peritoneal or lung metastases.

Circulating tumour DNA as a biomarker in resectable and irresectable stage IV colorectal cancer; a systematic review and meta-analysis

BACKGROUND

For patients with metastatic colorectal cancer, stratification for treatment (surgery or chemotherapy) is often based on crude clinicopathological characteristics like tumour size and number of lesions. Circulating tumour DNA (ctDNA) acts as a potential biomarker of disease trajectory and biology, allowing better stratification. This study aims to systematically review ctDNA in stage IV colorectal cancer to assess its potential role as a prospective biomarker to guide management decisions.

METHODS

A literature search was performed to identify studies where the measurement of ctDNA in stage IV colorectal cancer was correlated with a clinical outcome (radiological response, secondary resection rate, PFS, DFS or OS).

RESULTS

Twenty-eight studies were included, reporting on 2823 patients. Circulating tumour DNA was detectable in between 80% and 90% of patients prior to treatment. Meta-analysis identified a strong correlation between detectable ctDNA after treatment (surgery or chemotherapy) and overall survival (HR 2.2, 95% CI 1.79-2.69, p < 0.00001), as well as progression-free survival (HR 3.15, 95% CI 2.10-4.73, p < 0.00001). ctDNA consistently offered an early marker of long-term prognosis in irresectable disease, with changes after one cycle of systemic therapy demonstrating prognostic value. In resectable disease treated with curative intent, detection of ctDNA offered a lead time over radiological recurrence of 10 months.

CONCLUSION

Circulating tumour DNA is detectable in the majority of resectable and irresectable patients. The presence of ctDNA is clearly associated with shorter overall survival, with changes in ctDNA an early biomarker of adverse disease behaviour. Prospective trials are essential to test its clinical efficacy.

Clinical Utility of Plasma KRAS, NRAS and BRAF Mutational Analysis with Real Time PCR in Metastatic Colorectal Cancer Patients-The Importance of Tissue/Plasma Discordant Cases

BACKGROUND

Tumor tissue (T) mutational analysis represents the standard for metastatic colorectal cancer (mCRC); however, circulating tumor DNA (ctDNA) detected by liquid biopsy in plasma (PL) can better represent tumor heterogeneity.

METHODS

mCRC patients undergoing standard first-line chemotherapy with known T-KRAS/NRAS/BRAF status were enrolled in the present prospective study. PL mutations were assessed within 2 weeks before chemotherapy start with real time PCR and correlated with T status and Progression free survival (PFS). Clinical and biochemical variables including also total number of tumor lesions (TNL) and the sum of maximum diameter (SMD) of all lesions were assessed as potential predictors of T/PL discordance.

RESULTS

Among 45 enrolled patients, all BRAF mutations were concordant between T and PL and there were 20% of patients RAS discordant: 9% wild type in T and mutated in PL and 11% mutated in T and wild type in PL. T mutations were significantly associated to median PFS (mPFS of 4.5, 8.3 and 22.9 months for T-BRAF mutated, T-RAS mutated, and T-wild type patients, respectively, p for trend 0.00014). PL mutations further refined prognosis: RAS wild type in T and mutated in PL had significantly shorter PFS than concordant RAS wild type in T and PL: mPFS 9.6 vs. 23.3 months, respectively, p = 0.02. Patients RAS mutated in T and wild type in PL had longer PFS than concordant RAS mutated in T and PL: 24.4 vs. 7.8 months, respectively, p = 0.008. At a multivariate cox regression analysis for PFS, PL mutations were independent prognostic factor superior to T analysis (HR 0.13, p = 0.0008). At multivariate logistic regression analysis TNL and SMD were significant predictors of discordant cases.

CONCLUSIONS

PL mutational analysis allows a better prognostication than T analysis alone and could help in mCRC treatment management.

Evolution of Mutational Landscape and Tumor Immune-Microenvironment in Liver Oligo-Metastatic Colorectal Cancer

Simple Summary

About 10% of colorectal cancer patients presents with oligo-metastatic disease. The aim of our study was to assess genetic and immunologic dynamics underlying the oligo-metastatic status, evaluating genotype-phenotype correlations in a clean and homogeneous clinical model of liver-limited metastatic colorectal cancer. We show that loss of KRAS and SMAD4 mutations characterizes the oligo-metastatic disease while a progressive mutational evolution (gain in KRAS, PI3KCA, BRAF and SMAD4) is observed in poly-metastatic evolving disease. Furthermore, high granzyme-B+ T-cells infiltration is found in oligo-metastatic lesions. This study can support innovative strategies to monitor clinical evolution and to induce regressive genetic trajectories in cancer.

Abstract

Genetic dynamics underlying cancer progression are largely unknown and several genes involved in highly prevalent illnesses (e.g., hypertension, obesity, and diabetes) strongly concur to cancer phenotype heterogeneity. To study genotype-phenotype relationships contributing to the mutational evolution of colorectal cancer (CRC) with a focus on liver metastases, we performed genome profiling on tumor tissues of CRC patients with liver metastatic disease and no co-morbidities. We studied 523 cancer-related genes and tumor-immune microenvironment characteristics in primary and matched metastatic tissues. We observed a loss of KRAS and SMAD4 alterations and a high granzyme-B+ T-cell infiltration when the disease did not progress. Conversely, gain in KRAS, PIK3CA and SMAD4 alterations and scarce granzyme-B+ T-cells infiltration were observed when the tumor evolved towards a poly-metastatic spread. These findings provide novel insights into the identification of tumor oligo-metastatic status, indicating that some genes are on a boundary line between these two clinical settings (oligo- vs. poly-metastatic CRC). We speculate that the identification of these genes and modification of their evolution could be a new approach for anti-cancer therapeutic strategies.

Undetectable RAS-Mutant Clones in Plasma: Possible Implication for Anti-EGFR Therapy and Prognosis in Patients With RAS-Mutant Metastatic Colorectal Cancer

PURPOSE

Combining cetuximab with chemotherapy provides clinical benefit to 60% of the patients with RAS wild-type (RAS-wt) metastatic colorectal cancer (mCRC). This pilot study investigated the efficacy of cetuximab-based chemotherapy in a sample of patients (40%) with RAS mutation (RAS-mt) in their primary tumor whose circulating tumor DNA (ctDNA) was RAS-wt.

MATERIALS AND METHODS

The occurrence of Kirsten rat sarcoma viral oncogene homolog (KRAS), neuroblastoma rat sarcoma viral oncogene homolog (NRAS), V-raf murine sarcoma viral oncogene homolog B1 (BRAF), and PI3KCA mutations was determined in ctDNA by using a new ultrasensitive analysis based on mass spectrometry detection. All consenting patients with confirmed RAS-mt mCRC had disease progression on previous chemotherapy that contained no anti–epidermal growth factor receptor (EGFR). The patients with RAS-wt ctDNA received cetuximab + fluorouracil, leucovorin, and irinotecan (FOLFIRI), whereas those with RAS-mt ctDNA were treated with the oncologist’s choice of therapy.

RESULTS

Of 16 registered patients, 11 were male and five female. They were age 48 to 81 years, and they had unresectable metastatic adenocarcinoma from the colon (n = 11) or rectum (n = 5), with a median of two metastatic sites. They had received a median number of three previous chemotherapy protocols. Plasma genotyping identified RAS-mt in seven patients (44%) and RAS-wt in nine patients (56%). In the patients with wt ctDNA, objective tumor response rate was 50.0%, including one complete response and four partial responses after a median number of 6 courses of cetuximab + FOLFIRI (range, 1 to 16 courses). Two of the nine patients had stable disease, and two had progressive disease. No grade 3 to 4 toxicities were encountered. One-year survival rates were 60.0% for the patients with RAS-wt ctDNA and 17.9% for those with RAS-mt ctDNA. Median overall survival times were not reached and 4.7 months, respectively.

CONCLUSION

Patients with RAS-mt mCRC whose plasma biopsies contained RAS-wt could benefit from cetuximab-based therapy, a hypothesis to be tested in a prospective randomized trial.

Circulating Tumor DNA in KRAS positive colorectal cancer patients as a prognostic factor - a systematic review and meta-analysis

BACKGROUND

Liquid biopsy is a novel tool in oncology. It provides minimally invasive detection of tumor specific DNA. This review summarizes data on presence of circulating tumor DNA in serum or plasma of CRC patients as a potential negative prognostic factor.

MATERIALS AND METHODS

The systematic review was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The search was performed using PubMed, Web of Science and Scopus.

RESULTS

In total 18 articles with a total of 1779 patients met the inclusion criteria. Six out of 8 studies found that presence of ctDNA in plasma/serum was associated with inferior overall survival. All 6 studies found that high concentrations of ctDNA in plasma/serum was associated with inferior overall survival.

CONCLUSIONS

Presence or high concentrations of KRAS mutation in plasma or serum were associated with inferior prognosis. Establishing cut-off concentrations is warranted for further clinical implementation of liquid biopsy.

Clinical Significances of Positive Postoperative Serum CEA and Post-preoperative CEA Increment in Stage II and III Colorectal Cancer: A Multicenter Retrospective Study

Background: Carcinoembryonic antigen (CEA) is the most common serum tumor marker in colorectal cancer (CRC). Nevertheless, few previous studies demonstrated the impacts of postoperative CEA and post-preoperative CEA increment on prognosis of CRC.

Methods: Patients with stage II and III CRC were included from January 2009 to December 2015. All clinical and follow-up data were collected. Patients were divided into four different groups according to the levels of postoperative serum CEA and post-preoperative CEA trends. Chi-square test was used to analyze the relationship between clinical variables and categorized postoperative CEA and CEA increment. Cox proportional hazard regression was used for univariate and multivariable analyses. The log-rank test was performed to compare PFS and OS among groups.

Results: Patients, 1,008, who underwent radical surgery, were enrolled. Our results showed that positive postoperative CEA and CEA increment were related to clinical stage, T stage, N stage, tumor differentiation, and lymphatic invasion (p < 0.05). Univariate and multivariable analysis results suggested that positive postoperative CEA and CEA increment were independent prognostic factors for PFS (HR = 3.149, 95% CI, 2.426–4.088, p = 0.000 for postoperative CEA; HR = 2.708, 95% CI, 2.106–3.482, p = 0.000 for CEA increment) and OS (HR = 3.414, 95% CI, 2.549–4.574, p = 0.000 for postoperative CEA; HR = 2.373, 95% CI, 1.783–3.157, p = 0.000 for CEA increment). The survival analyses revealed positive postoperative CEA, and CEA increment predicted worse prognosis. Furthermore, our results indicated that the 3- and 5-year PFS rates were 86.6 and 78.4% in group A, but decreased to 25.3 and 7.2% in group D (p < 0.001). Similarly, the 3- and 5-year OS rates for group A were 92.5 and 83.9%, much higher than group D (p < 0.001). In other words, patients with both postoperative CEA elevation and CEA increment had the worst prognosis.

Conclusions: Positive postoperative CEA and CEA increment were independent prognostic factors for stage II and III CRC. Additionally, postoperative CEA and CEA increment had significant impacts on PFS and OS of CRC.

Cross-sectional analysis of circulating tumor DNA in primary colorectal cancer at surgery and during post-surgery follow-up by liquid biopsy

BACKGROUND

Liquid biopsy (LB) in early-stage, non-metastatic colorectal cancer (CRC) must be sensitive enough to detect extremely low circulating tumor DNA (ctDNA) levels. This challenge has been seldom and non-systematically investigated.

METHODS

Next generation sequencing (NGS) and digital PCR (dPCR) were combined to test tumor DNAs (tDNAs) and paired ctDNAs collected at surgery from 39 patients, 12 of whom were also monitored during the immediate post-surgery follow up. Patients treated for metastatic disease (n = 14) were included as controls.

RESULTS

NGS and dPCR concordantly (100% agreement) called at least one single nucleotide variant (SNV) in 34 tDNAs, estimated differences in allelic frequencies being negligible (±1.4%). However, despite dPCR testing, SNVs were only detectable in 15/34 (44.1%) ctDNAs from patients at surgery, as opposed to 14/14 (100%) metastatic patients. This was likely due to striking differences (average 10 times, up to 500) in ctDNA levels between groups. NGS revealed blood-only SNVs, suggesting spatial heterogeneity since pre-surgery disease stages, and raising the combined NGS/dPCR sensitivity to 58.8%. ctDNA levels at surgery correlated with neither tumor size, stage, grade, or nodal status, nor with variant abundance in paired tDNA. LB sensitivity reached 63.6% when ctDNA was combined with CEA. Finally, persistence and absence of ctDNA on the first conventional (month 3) post-surgery follow-up were associated with fast relapse and a disease-free status in 3 and 7 patients, respectively.

CONCLUSIONS

A simple clinical NGS/dPCR/CEA combination effectively addresses the LB challenge in a fraction of non-metastatic CRC patients.

Resistance to anti-epidermal growth factor receptor in metastatic colorectal cancer: What does still need to be addressed?

Colorectal cancer (CRC) represents a global health problem, being one of the most diagnosed and aggressive tumors. Cetuximab and panitumumab monoclonal antibodies (mAbs) in combination with chemotherapy are an effective strategy for patients with RAS Wild Type (WT) metastatic colorectal cancer (mCRC). However, tumors are often unresponsive or develop resistance. In the last years, molecular alterations in principal oncogenes (RAS, BRAF, PI3KCA, PTEN) in the downstream pathway of the epidermal growth factor receptor (EGFR) and in other receptors (HER2, MET) that converge on MAPK-ERK signalling have been identified as novel mechanisms of resistance to anti-EGFR strategies. However, further efforts are needed to better stratify CRCs and ensure more individualized treatments. Herein, we describe the consolidated molecular drivers of resistance and the therapeutic strategies available so far, with an overview on potential biomarkers of response that could be integrated in clinical practice.

Clinical Practice Use of Liquid Biopsy to Identify RAS/BRAF Mutations in Patients with Metastatic Colorectal Cancer (mCRC): A Single Institution Experience

Tumor heterogeneity represents a possible cause of error in detecting predictive genetic alterations on tumor tissue and can be overcome by testing alterations in circulating tumor DNA (ctDNA) using liquid biopsy. We assessed 72 consecutive patients with a diagnosis of metastatic colorectal cancer (mCRC) using Idylla™ Biocartis, a fully automated platform that evaluates the most frequent mutations of KRAS, NRAS and BRAF genes. We correlated the results of liquid biopsy and standard tissue-based next generation sequencing (NGS) analyses to patient clinical features. The overall agreement was 81.94%. Concordance was 85.71% and 96.15% in treatment-naïve patients and in the patient subgroup with liver metastases, respectively. In liver metastases positive, treatment-naïve patients, sensitivity, specificity and positive predictive value (PPV) were 92.31%, 100% and 100%, respectively. Circulating mutational fraction (CMF) was significantly higher in patients with liver metastases and high carcinoembryonic antigen (CEA) levels. In a subgroup of patients pre-treated with anti-Epidermal Growth Factor Receptor (EGFR) agents, emerging KRAS mutations were evidenced in 33% of cases. Testing RAS/BRAF mutations on plasma using the Idylla™ Biocartis platform is feasible and reliable in mCRC patients in clinical practice.