S. Siena

Phase II study of cetuximab in combination with cisplatin and docetaxel in patients with untreated advanced gastric or gastro-oesophageal junction adenocarcinoma (DOCETUX study)

Background:The conventional treatment options for advanced gastric patients remain unsatisfactory in terms of response rate, response duration, toxicity, and overall survival benefit. The purpose of this phase II study was to evaluate the activity and safety of cetuximab combined with cisplatin and docetaxel as a first-line treatment for advanced gastric or gastro-oesophageal junction adenocarcinoma.Methods:Untreated patients with histologically confirmed advanced gastric or gastro-oesophageal adenocarcinoma received cetuximab at an initial dose of 400 mg m−2 i.v. followed by weekly doses of 250 mg m−2, cisplatin 75 mg m−2 i.v. on day 1, docetaxel 75 mg m−2 i.v. on day 1, every 3 weeks, for a maximum of 6 cycles, and then cetuximab maintenance treatment was allowed in patients with a complete response, partial response, or stable disease.Results:Seventy-two patients (stomach 81.9% and gastro-oesophageal junction 18.1%; locally advanced disease 4.2%; and metastatic disease 95.8%) were enrolled. The ORR was 41.2% (95% CI, 29.5–52.9). Median time to progression was 5 months (95% CI, 3.7–5.4). Median survival time was 9 months (95% CI, 7–11). The most frequent grades 3–4 toxicity was neutropenia (44.4%). No toxic death was observed.Conclusions:The addition of cetuximab to the cisplatin/docetaxel regimen improved the ORR of the cisplatin/docetaxel doublet in the first-line treatment of advanced gastric and gastro-oesophageal junction adenocarcinoma, but this combination did not improve the TTP and OS. The toxicity of cisplatin/docetaxel chemotherapy was not affected by the addition of cetuximab.

BRAF codons 594 and 596 mutations identify a new molecular subtype of metastatic colorectal cancer at favorable prognosis

BACKGROUND While the negative prognostic role of BRAF V600E mutation in metastatic colorectal cancer (mCRC) is well established, the impact of BRAF codons 594 and 596 mutations, occurring in <1% of CRCs, is completely unknown. The present work aims to describe clinical, pathological and molecular features and prognosis of BRAF codons 594 and 596 mutant mCRCs, compared with BRAF V600E mutant and wild-type ones. PATIENTS AND METHODS Patients treated for mCRC at three Italian Institutions between October 2006 and October 2014, with available KRAS and NRAS codon 12, 13, 59, 61, 117 and 146 and BRAF codon 594, 596 and 600 mutational status, as detected by means of direct sequencing or matrix assisted laser desorption ionization time-of-flight MassArray, were included. RESULTS Ten patients bearing BRAF codons 594 or 596 mutated tumors were identified and compared with 77 and 542 patients bearing BRAF V600E mutated and BRAF wild-type tumors, respectively. While BRAF V600E mutated tumors were more frequently right-sided, mucinous and with peritoneal spread, BRAF 594 or 596 mutated were more frequently rectal, nonmucinous and with no peritoneal spread. All BRAF 594 or 596 mutated tumors were microsatellite stable. Patients with BRAF codons 594 or 596 mutated tumors had markedly longer overall survival (OS) when compared with BRAF V600E mutated [median OS: 62.0 versus 12.6 months; hazard ratio: 0.36 (95% confidence interval 0.20-0.64), P = 0.002], both at univariate and multivariate analyses. CONCLUSIONS BRAF codon 594 or 596 mutated mCRCs are different from BRAF V600E ones in terms of molecular features, pathological characteristics and clinical outcome. This is consistent with preclinical evidences of a kinase inactivating effect of these mutations. The role of CRAF in transducing the intracellular signal downstream BRAF 594 or 596 mutated proteins opens the way to further preclinical investigation.

Digital PCR quantification of MGMT methylation refines prediction of clinical benefit from alkylating agents in glioblastoma and metastatic colorectal cancer

BACKGROUND O(6)-methyl-guanine-methyl-transferase (MGMT) silencing by promoter methylation may identify cancer patients responding to the alkylating agents dacarbazine or temozolomide. PATIENTS AND METHODS We evaluated the prognostic and predictive value of MGMT methylation testing both in tumor and cell-free circulating DNA (cfDNA) from plasma samples using an ultra-sensitive two-step digital PCR technique (methyl-BEAMing). Results were compared with two established techniques, methylation-specific PCR (MSP) and Bs-pyrosequencing. RESULTS Thresholds for MGMT methylated status for each technique were established in a training set of 98 glioblastoma (GBM) patients. The prognostic and the predictive value of MGMT methylated status was validated in a second cohort of 66 GBM patients treated with temozolomide in which methyl-BEAMing displayed a better specificity than the other techniques. Cutoff values of MGMT methylation specific for metastatic colorectal cancer (mCRC) tissue samples were established in a cohort of 60 patients treated with dacarbazine. In mCRC, both quantitative assays methyl-BEAMing and Bs-pyrosequencing outperformed MSP, providing better prediction of treatment response and improvement in progression-free survival (PFS) (P < 0.001). Ability of methyl-BEAMing to identify responding patients was validated in a cohort of 23 mCRC patients treated with temozolomide and preselected for MGMT methylated status according to MSP. In mCRC patients treated with dacarbazine, exploratory analysis of cfDNA by methyl-BEAMing showed that MGMT methylation was associated with better response and improved median PFS (P = 0.008). CONCLUSIONS Methyl-BEAMing showed high reproducibility, specificity and sensitivity and was applicable to formalin-fixed paraffin-embedded tissues and cfDNA. This study supports the quantitative assessment of MGMT methylation for clinical purposes since it could refine prediction of response to alkylating agents.

Therapeutic implications of resistance to molecular therapies in metastatic colorectal cancer

Metastatic colorectal cancer (mCRC) patients carrying KRAS mutated tumors do not benefit from epidermal growth factor receptor (EGFR)-targeted cetuximab- or panitumumab-based therapies. Indeed, the mutational status of KRAS is currently a validated predictive biomarker employed to select mCRC patients for EGFR targeted drugs. When patients fail standard 5-fluorouracil-, oxaliplatin-, irinotecan- and bevacizumab-based therapies, EGFR-targeted salvage therapy can be prescribed only for those individuals with KRAS wild-type cancer. Thus, clinicians are now facing the urgent issue of better understanding the biology of KRAS mutant disease, in order to devise novel effective therapies in such defined genetic setting. In addition to KRAS, recent data point out that BRAF and PIK3CA exon 20 mutations hamper response to EGFR-targeted treatment in mCRC, potentially excluding from treatment also patients with these molecular alterations in their tumor. This review will focus on current knowledge regarding the molecular landscape of mCRC including and beyond KRAS, and will summarize novel rationally-developed combinatorial regimens that are being evaluated in early clinical trials.

Primary tumor sidedness has an impact on prognosis and treatment outcome in metastatic colorectal cancer: results from two randomized first-line panitumumab studies

Abstract Background Previous studies have reported the prognostic impact of primary tumor sidedness in metastatic colorectal cancer (mCRC) and its influence on cetuximab efficacy. The present retrospective analysis of two panitumumab trials investigated a possible association between tumor sidedness and treatment efficacy in first-line mCRC patients with RAS wild-type (WT) primary tumors. Materials and methods Data from two randomized first-line panitumumab trials were analyzed for treatment outcomes by primary tumor sidedness for RAS WT patients. PRIME (phase 3; NCT00364013) compared panitumumab plus FOLFOX versus FOLFOX alone; PEAK (phase 2; NCT00819780) compared panitumumab plus FOLFOX versus bevacizumab plus FOLFOX. Primary tumors located in the cecum to transverse colon were coded as right-sided, while tumors located from the splenic flexure to rectum were considered left-sided. Results Tumor sidedness ascertainment (RAS WT population) was 83% (n = 559/675); 78% of patients (n = 435) had left-sided and 22% (n = 124) had right-sided tumors. Patients with right-sided tumors did worse for all efficacy parameters compared with patients with left-sided disease in the RAS WT population and also in the RAS/BRAF WT subgroup. In patients with left-sided tumors, panitumumab provided better outcomes than the comparator treatment, including on median overall survival (PRIME: 30.3 versus 23.6 months, adjusted hazard ratio = 0.73, P = 0.0112; PEAK: 43.4 versus 32.0 months, adjusted hazard ratio = 0.77, P = 0.3125). Conclusion The results of these retrospective analyses confirm that in RAS WT patients, right-sided primary tumors are associated with worse prognosis than left-sided tumors, regardless of first-line treatment received. RAS WT patients with left-sided tumors derive greater benefit from panitumumab-containing treatment than chemotherapy alone or combined with bevacizumab, including an overall survival advantage (treatment difference: PRIME 6.7 months; PEAK 11.4 months). No final conclusions regarding optimal treatment could be drawn for RAS WT patients with right-sided mCRC due to the relatively low number of paxtients. Further research in this field is warranted. Trial registration (Clinicaltrials.gov) PRIME (NCT00364013), PEAK (NCT00819780).

Positron emission tomography response evaluation from a randomized phase III trial of weekly nab-paclitaxel plus gemcitabine versus gemcitabine alone for patients with metastatic adenocarcinoma of the pancreas

In a phase III pancreatic cancer study, tumor response by positron emission tomography (PET) (exploratory end point) predicted treatment efficacy, including longer overall survival. nab-Paclitaxel/gemcitabine had a significantly higher rate of metabolic response versus gemcitabine. Overall, 5× more patients had a metabolic response by PET compared with RECIST. PET may be a more sensitive measure of response than radiographic modalities.

Tumor MGMT promoter hypermethylation changes over time limit temozolomide efficacy in a phase II trial for metastatic colorectal cancer

BACKGROUND Objective response to dacarbazine, the intravenous form of temozolomide (TMZ), in metastatic colorectal cancer (mCRC) is confined to tumors harboring O(6)-methylguanine-DNA-methyltransferase (MGMT) promoter hypermethylation. We conducted a phase II study of TMZ enriched by MGMT hypermethylation in archival tumor (AT), exploring dynamic of this biomarker in baseline tumor (BT) biopsy and plasma (liquid biopsy). PATIENTS AND METHODS We screened 150 mCRC patients for MGMT hypermethylation with methylation-specific PCR on AT from FFPE specimens. Eligible patients (n = 29) underwent BT biopsy and then received TMZ 200 mg/m(2) days 1-5 q28 until progression. A Fleming single-stage design was used to determine whether progression-free survival (PFS) rate at 12 weeks would be ≥35% [H0 ≤ 15%, type I error = 0.059 (one-sided), power = 0.849]. Exploratory analyses included comparison between MGMT hypermethylation in AT and BT, and MGMT methylation testing by MethylBEAMing in solid (AT, BT) and LB with regard to tumor response. RESULTS The PFS rate at 12 weeks was 10.3% [90% confidence interval (CI) 2.9-24.6]. Objective response rate was 3.4% (90% CI 0.2-15.3), disease control rate 48.3% (90% CI 32.0-64.8), median OS 6.2 months (95% CI 3.8-7.6), and median PFS 2.6 months (95% CI 1.4-2.7). We observed the absence of MGMT hypermethylation in BT in 62.7% of tumors. CONCLUSION Treatment of mCRC with TMZ driven by MGMT promoter hypermethylation in AT samples did not provide meaningful PFS rate at 12 weeks. This biomarker changed from AT to BT, indicating that testing BT biopsy or plasma is needed for refined target selection.

Dynamic molecular analysis and clinical correlates of tumor evolution within a phase II trial of panitumumab-based therapy in metastatic colorectal cancer.

Abstract Background Mutations in rat sarcoma (RAS) genes may be a mechanism of secondary resistance in epidermal growth factor receptor inhibitor-treated patients. Tumor-tissue biopsy testing has been the standard for evaluating mutational status; however, plasma testing of cell-free DNA has been shown to be a more sensitive method for detecting clonal evolution. Materials and methods Archival pre- and post-treatment tumor biopsy samples from a phase II study of panitumumab in combination with irinotecan in patients with metastatic colorectal cancer (mCRC) that also collected plasma samples before, during, and after treatment were analyzed for emergence of mutations during/post-treatment by next-generation sequencing and BEAMing. Results The rate of emergence of tumor tissue RAS mutations was 9.5% by next-generation sequencing (n = 21) and 6.3% by BEAMing (n = 16). Plasma testing of cell-free DNA by BEAMing revealed a mutant RAS emergence rate of 36.7% (n = 39). Exploratory outcomes analysis of plasma samples indicated that patients who had emergent RAS mutations at progression had similar median progression-free survival to those patients who remained wild-type at progression. Serial analysis of plasma samples showed that the first detected emergence of RAS mutations preceded progression by a median of 3.6 months (range, −0.3 to 7.5 months) and that there did not appear to be a mutant RAS allele frequency threshold that could predict near-term outcomes. Conclusions This first prospective analysis in mCRC showed that serial plasma biopsies are more inclusive than tissue biopsies for evaluating global tumor heterogeneity; however, the clinical utility of plasma testing in mCRC remains to be further explored. ClinicalTrials.gov Identifier NCT00891930

Tracking a CAD-ALK gene rearrangement in urine and blood of a colorectal cancer patient treated with an ALK inhibitor

Background Monitoring response and resistance to kinase inhibitors is essential to precision cancer medicine, and is usually investigated by molecular profiling of a tissue biopsy obtained at progression. However, tumor heterogeneity and tissue sampling bias limit the effectiveness of this strategy. In addition, tissue biopsies are not always feasible and are associated with risks due to the invasiveness of the procedure. To overcome these limitations, blood-based liquid biopsy analysis has proven effective to non-invasively follow tumor clonal evolution. Patients and methods We exploited urine cell-free, trans-renal DNA (tr-DNA) and matched plasma circulating tumor DNA (ctDNA) to monitor a metastatic colorectal cancer patient carrying a CAD-ALK translocation during treatment with an ALK inhibitor. Results Using a custom next generation sequencing panel we identified the genomic CAD-ALK rearrangement and a TP53 mutation in plasma ctDNA. Sensitive assays were developed to detect both alterations in urine tr-DNA. The dynamics of the CAD-ALK rearrangement in plasma and urine were concordant and paralleled the patients clinical course. Detection of the CAD-ALK gene fusion in urine tr-DNA anticipated radiological confirmation of disease progression. Analysis of plasma ctDNA identified ALK kinase mutations that emerged during treatment with the ALK inhibitor entrectinib. Conclusion We find that urine-based genetic testing allows tracing of tumor-specific oncogenic rearrangements. This strategy could be effectively applied to non-invasively monitor tumor evolution during therapy. The same approach could be exploited to monitor minimal residual disease after surgery with curative intent in patients whose tumors carry gene fusions. The latter could be implemented without the need of patient hospitalization since urine tr-DNA can be self-collected, is stable over time and can be shipped at specified time-points to central labs for testing.

448PDRXDX-101, AN ORAL PAN-TRK, ROS1, AND ALK INHIBITOR, IN PATIENTS WITH ADVANCED SOLID TUMORS WITH RELEVANT MOLECULAR ALTERATIONS

ABSTRACT Aim: RXDX-101 is a small molecule inhibitor of TrkA, TrkB, TrkC, ROS1 and ALK, with high potency and selectivity. RXDX-101 demonstrated potent pharmacological activity in preclinical studies and is potentially first-in-class against the Trk family of kinases. This study aims to determine MTD, PD, PK and anti-tumor activity in patients with advanced cancer and applicable molecular alterations. Methods: Phase 1 dose escalation in patients with advanced solid tumors. RXDX-101 was dosed orally once/day in a 4 day on, 3 day off schedule for 3 weeks, followed by a 7 day rest period, in continuous 28-day cycles. Minimum of 3 patients were enrolled at each dose level. Endpoints include safety, PK, and tumor response by RECIST. Results: 19 patients have been treated at 6 dose levels (100, 200, 400, 800,1200 and 1600 mg/m2). RXDX-101 has been well tolerated to date; the MTD has not been reached. No DLT has been seen at any dose level. The most common AEs (mainly grade 1-2) considered possibly treatment-related included asthenia, paresthesias, nausea and diarrhea. Possibly related grade 3/4 AEs include asthenia and increased lipase. No treatment-related SAEs were observed. A patient with colorectal carcinoma (TrkA+) has a PR and is in cycle 2. Two patients with NSCLC (1 ROS1 + ; 1 ALK+) have also achieved PRs. An additional patient with neuroblastoma (ALK+) has a PR and is currently in cycle 16. Two patients have had prolonged stabilization of their disease and remain on treatment: a patient with NSCLC (ALK+) in cycle 14 and a patient with pancreatic cancer (ROS1+) in cycle 11. PK analysis shows maximum concentrations of RXDX-101 were generally achieved within 2 to 4 hours following dosing and exposure increased in an approximate dose proportional manner up to doses of 800 mg/M2 with minimal accumulation following multiple doses. Mean terminal half-life was 21- 32 hours and steady state reached within 4 days. Conclusions: RXDX-101 has been well tolerated in patients with advanced solid tumors. Early responses in patients with 3 different relevant molecular alterations are promising. PK profile seems suitable for once daily dosing, which is being evaluated. A global phase I/II trial was recently initiated. Disclosure: F.G.M. De Braud: Consultant or Advisory Roles Novartis Compensated Bristol-Myers Squibb; ompensated Roche Compensated Stock Ownership No Honoraria No Research Funding Yes; E. Ardini: Senior Scientist, Nerviano Medical Sciences Employee Compensated; M. Martignoni: CLIOSS Employee, Clinical Leader Compensated; A. Isacchi: Director, Nerviano Medical Sciences Compensated Employee; P. Pearson: Consultant Role Ignyta, Inc. Compensated Stock Ownership Ignyta, Inc.; D. Luo: Ignyta, Inc. Employee Sr. Director, Clinical Operations Compensated; J.L. Freddo: Consultant Role; Member Board of Directors Ignyta, Inc. Compensated Stock Ownership, Ignyta, Inc. Yes; S. Siena: Consultant or Advisory Role Amgen Compensated Bayer Compensated Celgene Compensated Sanofi Compensated Roche Compensated; tock Ownership No Research Funding Bayer. All other authors have declared no conflicts of interest.