Multimodal detection of molecular residual disease in high-risk locally advanced squamous cell carcinoma of the head and neck

Up to 30% of patients with locally advanced head and neck squamous cell carcinoma (LA-HNSCC) relapse. Molecular residual disease (MRD) detection using multiple assays after definitive therapy has not been reported. In this study, we included patients with LA-HNSCC (stage III Human Papilloma virus (HPV)-positive, III-IVB HPV-negative) treated with curative intent. Plasma was collected pre-treatment, at 4-6 weeks (FU1) and 8-12 weeks (FU2) post-treatment. Circulating tumor DNA (ctDNA) was analyzed using a tumor-informed (RaDaR®) and a tumor-naïve (CAPP-seq) assay. HPV DNA was measured using HPV-sequencing (HPV-seq) and digital PCR (dPCR). A total of 86 plasma samples from 32 patients were analyzed; all patients with at least 1 follow-up sample. Most patients were stage III HPV-positive (50%) and received chemoradiation (78%). No patients had radiological residual disease at FU2. With a median follow-up of 25 months, there were 7 clinical relapses. ctDNA at baseline was detected in 15/17 (88%) by RaDaR and was not associated with recurrence free survival (RFS). Two patients relapsed within a year after definitive therapy and showed MRD at FU2 using RaDaR; detection of ctDNA during follow-up was associated with shorter RFS (p < 0.001). ctDNA detection by CAPP-seq pre-treatment and during follow-up was not associated with RFS (p = 0.09). HPV DNA using HPV-seq or dPCR during follow-up was associated with shorter RFS (p < 0.001). Sensitivity and specificity for MRD at FU2 using RaDaR was 40% and 100% versus 20 and 90.5% using CAPP-seq. Sensitivity and specificity for MRD during follow-up using HPV-seq was 100% and 91.7% versus 50% and 100% using dPCR. In conclusion, HPV DNA and ctDNA can be detected in LA-HNSCC before definitive therapy. The RaDaR assay but not CAPP-seq may detect MRD in patients who relapse within 1 year. HPV-seq may be more sensitive than dPCR for MRD detection.

Early changes in tumor-naive cell-free methylomes and fragmentomes predict outcomes in pembrolizumab-treated solid tumors

Early kinetics of circulating tumor DNA (ctDNA) in plasma predict response to pembrolizumab, but typically requires sequencing of matched tumor tissue or fixed gene panels. We analyzed genome-wide methylation and fragment length profiles using cell-free methylated DNA immunoprecipitation and sequencing (cfMeDIP-seq) in 204 plasma samples from 87 patients before and during treatment with pembrolizumab from a pan-cancer phase II investigator-initiated trial (INSPIRE). We trained a pan-cancer methylation signature using independent methylation array data from The Cancer Genome Atlas to quantify a cancer-specific methylation (CSM) and fragment length score (FLS) for each sample. CSM and FLS are strongly correlated with tumor-informed ctDNA levels. Early kinetics of CSM predict overall survival and progression-free survival, independently of tumor type, PD-L1, and tumor mutation burden. Early kinetics of FLS are associated with overall survival independently of CSM. Our tumor-naïve mutation-agnostic ctDNA approach integrating methylomics and fragmentomics could predict outcomes in patients treated with pembrolizumab.

Genomic Characterization and Clinical Outcomes of Patients with Peritoneal Metastases from the AACR GENIE Biopharma Collaborative Colorectal Cancer Registry

Peritoneal metastases (PM) are common in metastatic colorectal cancer (mCRC). We aimed to characterize patients with mCRC and PM from a clinical and molecular perspective using the American Association of Cancer Research Genomics Evidence Neoplasia Information Exchange (GENIE) Biopharma Collaborative (BPC) registry. Patients' tumor samples underwent targeted next-generation sequencing. Clinical characteristics and treatment outcomes were collected retrospectively. Overall survival (OS) from advanced disease and progression-free survival (PFS) from start of cancer-directed drug regimen were estimated and adjusted for the left truncation bias. A total of 1,281 patients were analyzed, 244 (19%) had PM at time of advanced disease. PM were associated with female sex [OR: 1.67; 95% confidence interval (CI): 1.11-2.54; P = 0.014] and higher histologic grade (OR: 1.72; 95% CI: 1.08-2.71; P = 0.022), while rectal primary tumors were less frequent in patients with PM (OR: 0.51; 95% CI: 0.29-0.88; P < 0.001). APC occurred less frequently in patients with PM (N = 151, 64% vs. N = 788, 79%) while MED12 alterations occurred more frequently in patients with PM (N = 20, 10% vs. N = 32, 4%); differences in MED12 were not significant when restricting to oncogenic and likely oncogenic variants according to OncoKB. Patients with PM had worse OS (HR: 1.45; 95% CI: 1.16-1.81) after adjustment for independently significant clinical and genomic predictors. PFS from initiation of first-line treatment did not differ by presence of PM. In conclusion, PM were more frequent in females and right-sided primary tumors. Differences in frequencies of MED12 and APC alterations were identified between patients with and without PM. PM were associated with shorter OS but not with PFS from first-line treatment.

SIGNIFICANCE

Utilizing the GENIE BPC registry, this study found that PM in patients with colorectal cancer occur more frequently in females and right-sided primary tumors and are associated with worse OS. In addition, we found a lower frequency of APC alterations and a higher frequency in MED12 alterations in patients with PM.

Tumor-Naïve Circulating Tumor DNA as an Early Response Biomarker for Patients Treated With Immunotherapy in Early Phase Clinical Trials

PURPOSE

To evaluate early circulating tumor DNA (ctDNA) kinetics using a tumor-naïve assay and correlate it with clinical outcomes in early phase immunotherapy (IO) trials.

METHODS

Plasma samples were analyzed using a 425-gene next-generation sequencing panel at baseline and before cycle 2 (3-4 weeks) in patients with advanced solid tumors treated with investigational IO agents. Variant allele frequency (VAF) for mutations in each gene, mean VAF (mVAF) from all mutations, and change in mVAF between both time points were calculated. Hyperprogression (HyperPD) was measured using Matos and Caramella criteria.

RESULTS

A total of 162 plasma samples were collected from 81 patients with 27 different tumor types. Patients were treated in 37 different IO phase I/II trials, 72% of which involved a PD-1/PD-L1 inhibitor. ctDNA was detected in 122 plasma samples (75.3%). A decrease in mVAF from baseline to precycle 2 was observed in 24 patients (37.5%) and was associated with longer progression-free survival (hazard ratio [HR], 0.43; 95% CI, 0.24 to 0.77; P < .01) and overall survival (HR, 0.54; 95% CI, 0.3 to 0.96; P = .03) compared with an increase. These differences were more marked if there was a >50% decrease in mVAF for both progression-free survival (HR, 0.29; 95% CI, 0.13 to 0.62; P < .001) and overall survival (HR, 0.23; 95% CI, 0.09 to 0.6; P = .001). No differences in mVAF changes were observed between the HyperPD and progressive disease patients.

CONCLUSION

A decrease in ctDNA within 4 weeks of treatment was associated with treatment outcomes in patients in early phase IO trials. Tumor-naïve ctDNA assays may be useful for identifying early treatment benefits in phase I/II IO trials.

A Comprehensive Biomarker Analysis of Microsatellite Unstable/Mismatch Repair Deficient Colorectal Cancer Cohort Treated with Immunotherapy

The search for immunotherapy biomarkers in Microsatellite Instability High/Deficient Mismatch Repair system (MSI-H/dMMR) metastatic colorectal cancer (mCRC) is an unmet need. Sixteen patients with mCRC and MSI-H/dMMR (determined by either immunohistochemistry or polymerase chain reaction) treated with PD-1/PD-L1 inhibitors at our institution were included. According to whether the progression-free survival with PD-1/PD-L1 inhibitors was longer than 6 months or shorter, patients were clustered into the IT-responder group (n: 9 patients) or IT-resistant group (n: 7 patients), respectively. In order to evaluate determinants of benefit with PD-1/PD-L1 inhibitors, we performed multimodal analysis including genomics (through NGS panel tumour-only with 431 genes) and the immune microenvironment (using CD3, CD8, FOXP3 and PD-L1 antibodies). The following mutations were more frequent in IT-resistant compared with IT-responder groups: B2M (4/7 versus 2/9), CTNNB1 (2/7 versus 0/9), and biallelic PTEN (3/7 versus 1/9). Biallelic ARID1A mutations were found exclusively in the IT-responder group (4/9 patients). Tumour mutational burden did not correlate with immunotherapy benefit, neither the rate of indels in homopolymeric regions. Of note, biallelic ARID1A mutated tumours had the highest immune infiltration and PD-L1 scores, contrary to tumours with CTNNB1 mutation. Immune microenvironment analysis showed higher densities of different T cell subpopulations and PD-L1 expression in IT-responders. Misdiagnosis of MSI-H/dMMR inferred by discordances between immunohistochemistry and polymerase chain reaction was only found in the IT-resistant population (3/7 patients). Biallelic ARID1A mutations and Wnt signalling activation through CTNNB1 mutation were associated with high and low T cell immune infiltrates, respectively, and deserve special attention as determinants of response to PD-1/PD-L1 inhibitors. The non-MSI-H phenotype in dMMR is associated with poor benefit to immunotherapy. Our results suggest that mechanisms of resistance to immunotherapy are multi-factorial.

Increase in serum choline levels predicts for improved progression-free survival (PFS) in patients with advanced cancers receiving pembrolizumab

Background

Recent studies have demonstrated that T cells can induce vasodilation in a choline-acetyltransferase dependent manner, leading to an increase in T cell migration to infected tissues in response to viral infection, but its role in cancer is unclear. Choline acetyltransferase catalyzes the production of acetylcholine from choline and acetyl-CoA, however, acetylcholine is challenging to quantify due to its extremely short half-life while choline is stable. This study aims to correlate serum choline levels in patients with advanced solid tumors receiving pembrolizumab with treatment outcomes.

Methods

Blood samples were collected at baseline and at week 7 (pre-cycle 3) in patients treated with pembrolizumab in the INvestigator-initiated Phase 2 Study of Pembrolizumab Immunological Response Evaluation phase II trial (NCT02644369). Samples were analyzed for choline and circulating tumor DNA (ctDNA). Multivariable Cox models were used to assess the association between choline and overall survival (OS) and progression-free survival (PFS) when including ΔctDNA_C3 (the change in ctDNA from baseline to cycle 3), cohort, PD-L1 expression and tumor mutation burden (TMB). An independent validation cohort from the LIBERATE study (NCT03702309) included patients on early phase trials treated with a PD-1 inhibitor.

Results

A total of 106 pts were included in the analysis. With a median follow-up of 12.6 months, median PFS and OS were 1.9 and 13.7 months, respectively. An increase in serum choline level at week 7 compared with baseline (Δcholine_C3) in 81 pts was significantly associated with a better PFS (aHR 0.48, 95% CI 0.28 to 0.83, p=0.009), and a trend toward a better OS (aHR 0.64, 95% CI 0.37 to 1.12, p=0.119). A combination of ΔctDNA_C3 and Δcholine_C3 was prognostic for both OS and PFS. Multivariable analyses show Δcholine_C3 was a prognostic factor for PFS independent of ΔctDNA_C3, cohort, PD-L1 and TMB. In the independent validation cohort (n=51), an increase in serum choline at cycle 2 was associated with a trend to improved PFS.

Conclusions

This is the first exploratory report of serum choline levels in pan-cancer patients receiving pembrolizumab. The association between improved PFS and Δcholine_C3 suggests a possible role for the cholinergic system in the regulation of antitumor immunity. Further pre-clinical and clinical studies are required to validate this finding.

Trial registration number

NCT03702309.

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.

Using real-word data to evaluate the effects of broadening eligibility criteria in oncology trials

Eligibility criteria restrict patient enrollment in clinical trials. A Nature paper applied a machine-learning algorithm in a real-world database to show that relaxing some criteria may not jeopardize efficacy and safety. This may enable more patients to have earlier access to new therapies and make results more generalizable to clinical practice.

MONEO: A phase II study of avelumab (Av) plus FLOT in the peri-operative treatment for patients (pts) with resectable gastric or gastroesophageal junction cancer (GC)

TPS4155

Background: GC represents a worldwide problem; radical surgery remaining the gold standard of curative treatment. In the West, even with peri-operative chemotherapy, 5-year survival rate is approximately 40%. GC is a heterogeneous disease, well characterized by different molecular classifications, all having in common the role of the immune system and a T-cell inflamed phenotype across all subtypes. The anti-PD-L1 Av antibody has demonstrated efficacy in GC with response rates of around 10% in the refractory setting. The addition of other immune checkpoint inhibitors to chemotherapy have demonstrated efficacy in the metastatic setting. The combination of Av to perioperative chemotherapy may increase pathological responses by a synergistic effect, and then improving the survival (OS). Methods: The MONEO is an open-label, non-randomized, multicentric, phase II study that explores the combination of Av plus peri-operative FLOT (docetaxel, oxaliplatin, fluorouracil/leucovorin) in resectable GC pts. EudraCT 2019-000782-21; ClinicalTrials NCT03979131. Main inclusion criteria require pts with histologically proven GC, stage Ib (T1N1 only) - IIIC (7th AJCC Ed), available paraffin block from diagnosis and surgery, evaluable disease (RECIST 1.1) amenable to radical surgery. Significant comorbidities and active autoimmune diseases are excluded. Treatment consists of surgery with 4 peri-operatory cycles of FLOT + Av, followed by Av up to one year. The primary objective is the pathological complete response (pCR) rate, compared to historical data. Secondary objectives include OS, disease-free survival, R0 resection rate, tolerability and biomarker analysis. Key point is the comprehensive biomarker analysis from tissue and blood samples (pathological immune response, TCR clonality, immune contexture characterization, immunodynamic monitoring). Statistics for an estimated 33% pCR (historical 16%), 82% power, 0.1 one-side type I error. 37 pts will be recruited from 10 Spanish centers. The sponsor is Vall d'Hebron Institute of Oncology (VHIO), principal investigators Dr. Melero and Dr. Alsina. In compliance with the Helsinki Declaration. At a data cut-off day of 5th of February 2021, 38 patients have been enrolled, 27 of them have had the surgery. Although the difficulties during the COVID19 pandemia, only two patients had been withdrawn from the study. Clinical trial information: NCT03979131.

Identifying burnout in young oncologists: The sooner the better

11010

Background: Professional burnout is an important issue for the healthcare systems with potentially relevant consequences in the quality of patient care. Young oncologists are a special risk population, due to high workload, academic pressure and other specific factors related to cancer care. Work life and lifestyle factors are related with burnout levels and may define specific interventions to reduce and prevent burnout. Methods: A survey based on the validated Maslach Burnout Inventory Human Services Survey for Medical Personnel (MBI-HSS MP) was conducted. Additional questions to explore work life and lifestyle factors were included. We studied potential burnout amongst young Spanish oncologists (residents and oncologist in the first 5 years of professional performance). Statistical analyses, including linear regression, were carried out to test the relations between overall burnout score and work and lifestyle factors. Results: We obtained 243 responses to the survey. The sample was representative in terms of age, sex, geographic region, professional profile (residents and young oncologists) and a homogeneous distribution per year of residence (final participation rate was of 26.6%). Regarding 5 Burnout profiles, 32.1% of the participants were classified as Ineffective, 25.1% as Burnout, 21% as Engaged, 17.3% as Overextended and 4.5% as Disengaged. Percentage of Burnout profile is higher in medical oncology residents (28.24%) than in young oncologists (19.79%). The highest percentage of burnout profile was observed in the second-year residents (35,71%) and gradually decreases, in parallel to an increase in the engaged profile. The multivariable linear regression analysis showed a significant correlation between not having a good work life balance and adequate vacation time and the burnout score. Conclusions: Burnout affects a significant number of young oncologists with significantly different profiles and differences across regions. Adapted interventions to the most frequent profiles and at different stages of the training and professional career may be necessary particularly at the early beginning. Actions towards achieving a better work and personal life balance and stress management could be effective. These results are the basis for the prospective part of our study that aims to design an intervention and to assess its efficacy in this population.

Real-world application of liquid biopsy in gastrointestinal tumors: Experience from a comprehensive cancer center

e14546

Background: Determination of circulating tumoral DNA (ctDNA) in plasma has recently emerged as an alternative to genomic testing in solid biopsy. Although different clínical trials have suggested that ctDNA alterations can tailor patient's treatment, its routinary utility in clinical practice is still controversial. Methods: A total of 74 consecutive plasma samples from 63 patients (pts) have been collected from October 2017 to December 2018 in our center and analyzed using two different next-generation sequencing (NGS) platforms: OncoTRACE (OT) and Guardant360 (G360). Main epidemiological, pathological and clinical data have been retrospectively extracted from medical records and correlation with ctDNA alterations have been performed using Chi-Square test. Application of liquid biopsy results has been decided after discussion in molecular tumor board and physician’s opinion. Results: OT and G360 were performed in 63 and 11 plasma samples respectively. Most part of the samples were from pancreatic (34; 45.9%) and colorrectal (CRC) (28; 25.7%) adenocarcinoma pts although biliary tract, gastric and oesophageal carcinoma pts were also included (4 each; 5.4%). Plasma samples were analyzed after progression to ≥two systemic therapies in 48.6%. At least one pathogenic alteration of ctDNA was detected in 44.6% of the samples. No correlation has been observed between presence of alteration in ctDNA and tumor origin, surgery of the primary, number and location of metastases and CEA and CA19.9. ctDNA alteration could be targetable with approved or experimental therapies in 14 pts (20.9%; 6 pts OT and 8 pts G360): 9 pts with CRC ( BRAF, EGFR, RAS, PI3KCA, PTEN), 2pts with pancreatic ( IDH1, BRCA1) and 1 pt with gastric, oesophageal and biliary tract carcinoma ( PTEN, EZH2, IDH1). However, these results have been applied in 4 pts (6% of all pts, 28.6% with targeteable ctDNA alterations): 3 pts were treatment-naïve and 1 pt had progressive disease to 2 systemic therapies. Most part of the patients with targetable alterations who did not receive treatment was due to clinical deterioration. Conclusions: Detection of alterations in ctDNA using NGS platforms is feasible in gastrointestinal tumor patients and can help physicians to decide treatment, especially in CRC. However, many patients could not be treated according to ctDNA as plasma samples were collected in late stages of the disease.

BRAF mutant colorectal cancer: prognosis, treatment, and new perspectives

The MAPK cascade plays a crucial role in tumor cell proliferation and survival. Accumulating evidence suggests that mutations in the BRAF oncogene are not only associated with poor prognosis but also linked with less benefit when treated with anti-epidermal growth factor receptor antibodies in metastatic colorectal cancer (mCRC). Targeting this molecular aberration has thus become a matter of particular interest in mCRC drug development. In contrast to other malignances such as BRAF mutant melanoma, efficacy observed with BRAF inhibitors in monotherapy in mCRC is poor. Several mechanisms of resistance have been identified leading to the development of different treatment strategies that have shown promising activity in early clinical trials. Hence, rational combination of targeted therapies is expected to further increase the efficacy of selective BRAF inhibitors. Herein, we discuss the main clinical and molecular characteristics of BRAF mutant colorectal cancer and its translation into the clinic, with a focus on developmental therapeutics and combination strategies. In addition, we contextualize the available data with potential future approaches that include the extended access to next-generation sequencing platforms and gene expression strategies for molecular subtyping. These approaches will facilitate the identification of certain patient profiles providing more therapeutic possibilities.

Analysis of mutant allele fractions in driver genes in colorectal cancer - biological and clinical insights

Sequencing of tumors is now routine and guides personalized cancer therapy. Mutant allele fractions (MAFs, or the ‘mutation dose’) of a driver gene may reveal the genomic structure of tumors and influence response to targeted therapies. We performed a comprehensive analysis of MAFs of driver alterations in unpaired primary and metastatic colorectal cancer (CRC) at our institution from 2010 to 2015 and studied their potential clinical relevance. Of 763 CRC samples, 622 had detailed annotation on overall survival in the metastatic setting (OSmet) and 89 received targeted agents matched to KRAS (MEK inhibitors), BRAF (BRAF inhibitors), or PIK3CA mutations (PI3K pathway inhibitors). MAFs of each variant were normalized for tumor purity in the sample (adjMAFs). We found lower adjMAFs for BRAF^V600E and PIK3CA than for KRAS,NRAS, and BRAF non‐V600 variants. TP53 and BRAF^V600E adjMAFs were higher in metastases as compared to primary tumors, and high KRAS adjMAFs were found in CRC metastases of patients with KRAS wild‐type primary tumors previously exposed to EGFR antibodies. Patients with RAS‐ or BRAF^V600E‐mutated tumors, irrespective of adjMAFs, had worse OSmet. There was no significant association between adjMAFs and time to progression on targeted therapies matched to KRAS,BRAF, or PIK3CA mutations, potentially related to the limited antitumor activity of the employed drugs (overall response rate of 4.5%). In conclusion, the lower BRAF^V600E and PIK3CA adjMAFs in subsets of primary CRC tumors indicate subclonality of these driver genes. Differences in adjMAFs between metastases and primary tumors suggest that approved therapies may result in selection of BRAF^V600E‐ and KRAS‐resistant clones and an increase in genomic heterogeneity with acquired TP53 alterations. Despite significant differences in prognosis according to mutations in driver oncogenes, adjMAFs levels did not impact on survival and did not help predict benefit with matched targeted agents in the metastatic setting.

Clinical and molecular determinants of treatment benefit with phase I trials in patients (pts) with advanced pancreatic cancer (PC)

409

Background: PC is the 4th leading cause of cancer-related death, with limited efficacy of systemic treatment (tx) beyond first-line chemotherapy (chemo). We aimed to assess the potential benefit of phase 1 trials in this setting. Methods: From 2011 to 2016, 49 pts were enrolled in 54 phase 1 trials at our institution. Clinical and molecular data were retrospectively extracted from medical records. Time to progression (TTP) was calculated from time of tx start to discontinuation due to progressive disease, and clinical benefit rate (CBr) was defined as partial response or stable disease > 4 months. Results: Median age was 58 (41-75), 69% were male, 60% had metastases in liver. Most pts received gemcitabine-based regimens (47%) or Folforinox (32%) as first-line tx (median TTP of 5.63 months [CI 95% 4.0-8.1]). Median tx line of Phase 1 trial was 3 (range 2-5). Regimens included chemo or immunotherapies (chemo-imm group) in 16 cases (12 and 4, respectively), small molecule inhibitor (SMI) as single-agent in 19 cases (SMI.1 group), and SMI in combinations in 19 cases (SMI.2 group). In 17 cases, tx was matched to genomic profile; most frequent matches were PI3K + MEK SMI or RAF SMI ( KRAS mut in 7 pts), PI3K SMI ( PTEN loss/ PIK3CA mut in 3 pts) and PD1 blockade (PDL1 high in 4 pts). There were 3 (6%) partial responses (PI3K SMI unmatched, RAF SMI matched and anti-PD1 agent matched) and 12 (24%) disease stabilizations. Median TTP in phase 1 trial was 1.9 months [CI 95% 1.6-2.5], without significant differences if matched/unmatched agent (p = 0.5) or tx given as second-line/later regimen (p = 0.5). Median TTP was 2.7 months [CI95% 1.6-10.7] with chemo-imm (control arm), 2.0 months [CI95% 1.8-5.6] with SMI.2 (HR = 1.8, p = 0.13) and 1.4 months [CI95% 1.3-2.8] with SMI.1 (HR = 3.0, p = 0.004). This difference was maintained in a multivariable model (HR = 2.9, p = 0.005). CBr with chemo-imm (38%) or SMI.2 (21%) was higher as compared with SMI.1 (5%; p = 0.06). Conclusions: Selected PC pts are eligible to phase 1 trials and up to one-third derive substantial benefit from the intervention. In our experience, chemo-imm agents or targeted SMI given as combination regimens associate with longer TTP and CBr when compared with single-agent SMI.

Pharmacokinetic and pharmacodynamic evaluation of aflibercept for the treatment of colorectal cancer

INTRODUCTION

Colorectal cancer (CRC) is currently one of the most lethal and prevalent tumors worldwide. Prognosis in the metastatic setting remains poor despite therapeutic advances. In addition to chemotherapy, new drugs have recently been developed targeting signaling pathways involved in tumor growth, differentiation and angiogenesis. Aflibercept , a recombinant protein derived from VEGF receptors 1 and 2, also targets this angiogenesis pathway but via a different mechanism, acting as VEGF decoy, thus blocking other VEGFs.

AREAS COVERED

A comprehensive review of preclinical studies with aflibercept in cell lines and xenografts of different tumor types is presented. Aflibercept safety, pharmacokinetics and pharmacodynamics data from Phase I studies in solid tumor patients are discussed. Implications of Phase II studies and the pivotal Phase III VELOUR trial of second-line treatment in metastatic CRC (mCRC) patients evaluating aflibercept alone or combined with chemotherapy are also described.

EXPERT OPINION

In this challenging field, aflibercept offers a good option for oxaliplatin-refractory mCRC patients when combined with irinotecan and 5-fluorouracil irrespective of prior anti-angiogenic treatment. Therapeutic management may be further advanced by characterization of patients with predictive biomarkers and molecular profiles to improve benefit with this treatment.

Prognostic impact of primary tumor site location in metastatic colorectal cancer (mCRC)

578

Background: CRC site is associated with differences in key molecular features that may impact survival in the metastatic (met) setting. We assessed the magnitude of outcome differences in a non-clinical trial scenario and explored how rectum cancer (RC) compares with right- and left-sided (RS and LS) colon tumors. Methods: Retrospective analysis of clinicopathological and molecular data from all mCRC patients (pts) treated at VHIO from January 2010 to June 2015. Targeted mutation (mut) profiling of driver oncogenes was performed by mass spectrometry (MassARRAY, Sequenom) or with next generation sequencing (Amplicon MiSeq, Illumina). Survival after relapse (SAR) was defined as time from diagnosis of met disease to death. Tumor site was categorized as RS (cecum, ascending, hepatic flexure, and transverse), LS (splenic flexure, descending, and sigmoid) or RC. We performed Cox proportional hazards models and adjusted for covariates including number and location of met sites, surgical resection of met lesions, and KRAS, BRAF and PIK3CA mut. Results: From 686 pts analyzed, primary site was RS/LS/RC in 29.4%/43.4%/27.2%, respectively. Pts with LS tumors were less likely to have ≥ 2 met sites (32%/20%/29%; p = 0.01). Lung metastases were more common in RC pts (20%/15%/36%; p < 0.001), peritoneal metastasis in pts with RS tumors (28%/14%/5%, p < 0.001). Surgical resection of any met disease was performed less frequently in pts with RS tumors (28%/46%/41%; p < 0.001). KRAS mut (59%/45%/44%), BRAF V600E mut (9%/5%/3%) and PIK3CAmut (25%/14%/11%) were more prevalent in RS tumors. In the overall population with survival data (n = 606, 424 events), SAR was significantly lower in pts with RS tumors (31/46/46 months; RS vs. LS HR = 1.54 [1.2-2.0], p < 0.001; rectum vs. left HR = 1.0 [0.7-1.3], p = 0.83). For comparison, worse SAR was also seen in the subset of pts (n = 337; 276 events) not eligible for surgical resection of met disease (26/31/35 months; right vs. left HR = 1.60 [1.2-2.2], p = 0.004; rectum vs. left HR = 0.9 [0.6-1.2], p = 0.42). Conclusions: The worse SAR of pts diagnosed with right-sided CRC tumors cannot be explained only by their distinctive met pattern or mutation profile of common oncogenes. Left-sided and rectum tumors have similar outcomes.

Survival determinants with matched targeted therapies in BRAF mutant metastatic colorectal cancer (mCRC)

649

Background: BRAF mutation (mt) occurs in 5-8% of mCRC and is associated with poor prognosis. Matched targeted therapies for this population are increasingly available in clinical trials. Methods: From Nov 2010 to June 2015, a total of 32 chemorefractory BRAF mt mCRC patients (pts) were enrolled in phase I trials with anti-BRAF matched therapy at Vall d´Hebron Institute of Oncology. BRAF mt was determined by real-time PCR (50%), mass spectrometry (Sequenom, 28%) or next-generation sequencing (Amplicon MiSeq, 22%). All demographic, treatment and survival data were retrospectively analyzed. Results: Median age was 60.4 years (range 42.8-73.5), 62% had right-sided CRC primaries and 59% were stage IV at diagnosis. Median treatment lines before matched therapy was 2 (range 1-4). Co-existing RNFA43, PI3KCA and GNAS mt were found in 4, 2 and 1 pts, respectively. Median time from diagnosis to start of anti-BRAF therapy was 18.6 months (m) (CI95% 14-36) and median time from diagnosis of mCRC to death was 28.4m (CI95% 25-50). A total of 41 anti-BRAF matched therapies were delivered, 9 pts received more than 1 regimen. BRAF inhibitor (inh) monotherapy was delivered in 34% of cases; BRAF plus MEK/EGFR/WNT/PI3K/CDK inh doublets or triplets to 37% and 29% pts, respectively. Survival from start of anti-BRAF to death was 8.9m (CI95% 7-15), without significant differences if 1 or more than 1 anti-BRAF regimen was given (HR: 0.82, p=0.6). Partial responses were observed in 7 cases (17%, 4 doublets and 3 triplets) and complete response in 2 cases (5%, 1 doublet and 1 triplet). Median time on treatment (ToT) with anti-BRAF therapy was 2.83m (CI95% 2-5.5). Of note, ToT was significantly longer for triplets compared to mono/doublets: 5.5m (CI95% 2.7-not reached) vs. 1.9m (CI95% 1.6-3.7; HR: 0.46 [CI95% 0.2-1.0], p=0.05). Median BRAFmt allele fraction (adjusted for tumor purity) was 0.25 (0.13-0.68); no correlation with ToT on anti-BRAF therapy was observed (p=0.36). Conclusions: In a selected BRAF mt population enrolled in early trials with anti-BRAF matched therapy at our institution, survival in the metastatic setting was remarkably high. Triplet matched therapies seem to control disease for longer time than mono/doublets.

Current and advancing treatments for metastatic colorectal cancer

INTRODUCTION

Colorectal cancer (CRC) is one of the leading causes of cancer deaths worldwide. Despite the introduction of several new drugs targeting the vascular endothelial growth factor or epidermal growth factor receptor (EGFR) signaling pathways, survival and disease control in metastatic CRC remains poor.

AREAS COVERED

Chemotherapy based on fluoropyrimidines and irinotecan or oxaliplatin has been the cornerstone of CRC standard of care for several decades. Optimal regimens are selected according to toxicity profiles and patient characteristics. The addition of targeted drugs inhibiting angiogenesis, notably bevacizumab, aflibercept and ramucirumab, has improved chemotherapy outcomes in metastatic CRC. Anti-EGFR agents, cetuximab and panitumumab, in combination with chemotherapy have also improved survival in patients with wild-type RAS tumors. In the refractory setting, there are emerging drugs such as regorafenib or TAS-102 that also have demonstrated impact on outcomes.

EXPERT OPINION

Drugs targeting signaling pathways involved in tumorigenesis improve patient outcomes over chemotherapy alone. Determining the most suitable combination and sequence should be carefully selected, with studies yet to provide a definitive solution to this unknown. Molecular mechanisms of colorectal cancer are at the forefront of research. Knowledge in this domain will help overcome resistance to therapies and introduce new drugs in the personalized CRC therapeutic scenario.

Elucidating the molecular aspects of colorectal cancer and their clinical importance

Over the last 10 years, crucial improvements have been made in the pursuit of more effective therapies for colorectal cancer (CRC). In understanding the basis of CRC biology we have evolved from the classical ‘adenoma to carcinoma transition’ hypothesis, to the identification of two CRC clusters (microsatellite instability and chromosomal instability) and further classifications based on epigenetic events. Thanks to these advances in molecular analyses, key pathways, notably that of the EGFR, are now integrated into standard practice for therapeutic management and other pathways are being explored for blocking driving mutations and overcoming drug resistance. Genetic profiling is being developed to better predict prognosis and treatment response. The CRC subtyping consortium has combined and reanalyzed genetic signature data sets from several international groups. A definitive genetic CRC classification is currently being established and will be critical for clinical development of therapeutic strategies.

Clinical and molecular characterization of refractory BRAF mutant metastatic colorectal carcinoma (mCRC): Vall d’Hebron Institute of Oncology phase I program cohort

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Background: BRAF mutation (mt) occurs in 5-8% of mCRC and its role as a negative prognostic factor is well known. The up-front detection of BRAF mt is not standardized beyond the boundaries of research. However, since novel emerging specific therapies are increasingly available in clinical trials, the prior determination of this mutation is now warranted. Methods: From 07/2010 to 01/2014, 581 patients (pts) with advanced refractory mCRCunderwent genetic tumor profiling as part of the VHIO Phase I Trial Molecular Prescreening Program. BRAF mt was determined by Sanger sequencing or multiplex PCR and mass detection (MassARRAY, Sequenom) of 268 frequent hotspots in 25 oncogenes including, KRAS, NRAS, and PIK3CA. PTEN status was also assessed by immunohistochemistry. Results: 581 samples were analyzed detecting BRAF mt in 56 (9.6%). In the BRAF mt population, median age was 61 years (45-80) and 54% had right-sided CRC. Metastatic sites were found at: liver 61%; peritoneum 52%; lung 39%. Median number of standard treatment was 4 (0-8) including cetuximab and/or panitumumab in 73%. BRAF V600E mutation was detected in 53 samples whereas V600K, D594V and D594G were seen in one sample each. PTEN was analyzed in 44.6% of samples resulting in low expression (H-score <50) in 56%. Other co-existing mutations were PIK3KCA H1047R, PIK3CA E545K, NRAS G12V, GNAS R201C and EGFR S768I. 22 pts were enrolled at least in one phase I trial with drugs targeting either BRAF alone (n=12) or combined with anti-EGFR (n=5), MEK (n=2), PI3K (n=1) inhibitors or double MEK/PI3K inhibition (n=2). Partial responses (PR) were seen in 3 pts (2 with BRAF inhibitor and EGFR inhibitor and 1 with BRAF inhibitor as a single agent). Conclusions: BRAF mt mCRC pts in our institution have a similar pattern to other series reported. Notably, PTEN low expression was present in almost half of the samples analyzed and other co-existent mutations in the ERK and PI3K pathways were detected. This observation, coupled with the clinical outcome observed with single agent BRAF inhibition in this population, suggests that these patients may derive greater benefit from dual BRAF and either EGFR, MEK or PI3K inhibition.