Combined BRAF, EGFR, and MEK Inhibition in Patients with BRAFV600E-Mutant Colorectal Cancer

Although BRAF inhibitor monotherapy yields response rates >50% in BRAFV600-mutant melanoma, only approximately 5% of patients with BRAFV600E colorectal cancer respond. Preclinical studies suggest that the lack of efficacy in BRAFV600E colorectal cancer is due to adaptive feedback reactivation of MAPK signaling, often mediated by EGFR. This clinical trial evaluated BRAF and EGFR inhibition with dabrafenib (D) + panitumumab (P) ± MEK inhibition with trametinib (T) to achieve greater MAPK suppression and improved efficacy in 142 patients with BRAFV600E colorectal cancer. Confirmed response rates for D+P, D+T+P, and T+P were 10%, 21%, and 0%, respectively. Pharmacodynamic analysis of paired pretreatment and on-treatment biopsies found that efficacy of D+T+P correlated with increased MAPK suppression. Serial cell-free DNA analysis revealed additional correlates of response and emergence of KRAS and NRAS mutations on disease progression. Thus, targeting adaptive feedback pathways in BRAFV600E colorectal cancer can improve efficacy, but MAPK reactivation remains an important primary and acquired resistance mechanism.Significance: This trial demonstrates that combined BRAF + EGFR + MEK inhibition is tolerable, with promising activity in patients with BRAFV600E colorectal cancer. Our findings highlight the MAPK pathway as a critical target in BRAFV600E colorectal cancer and the need to optimize strategies inhibiting this pathway to overcome both primary and acquired resistance. Cancer Discov; 8(4); 428-43. ©2018 AACR.See related commentary by Janku, p. 389See related article by Hazar-Rethinam et al., p. 417This article is highlighted in the In This Issue feature, p. 371.

Aflibercept Plus FOLFIRI vs. Placebo Plus FOLFIRI in Second-Line Metastatic Colorectal Cancer: a Post Hoc Analysis of Survival from the Phase III VELOUR Study Subsequent to Exclusion of Patients who had Recurrence During or Within 6 Months of Completing Adjuvant Oxaliplatin-Based Therapy

The aim of this post hoc analysis of the VELOUR study (ClinicalTrials.gov NCT00561470) was to investigate the treatment effect of adding aflibercept to second-line infusional 5-fluorouracil (5-FU), leucovorin and irinotecan (FOLFIRI) in patients with metastatic colorectal cancer (mCRC) who had failed any prior oxaliplatin-containing regimen. Adjuvant rapid relapsers (ARR), who were enrolled directly following relapse during or within 6 months of completion of oxaliplatin-containing adjuvant chemotherapy (N = 124, including 17 patients who also received bevacizumab as part of their adjuvant therapy), were excluded from the original VELOUR intention-to-treat (ITT) population (N = 1226). After exclusion of the ARR, overall survival (OS) in the ITT minus ARR (ITT-ARR) population (N = 1102) was longer in the aflibercept plus FOLFIRI arm than in the placebo plus FOLFIRI arm [hazard ratio (HR) 0.78, 95 % confidence interval (CI) 0.68-0.90; median survival difference 1.87 months]. In the subgroup of patients assigned to the prior bevacizumab stratum at randomization, OS was numerically longer in the aflibercept plus FOLFIRI arm than in the placebo plus FOLFIRI arm (HR 0.81; 95 % CI 0.63-1.04; median survival difference 2.14 months). Comparison of the post hoc analysis results with the primary analysis from VELOUR suggests that the inclusion of the directly enrolled ARR may have understated the aflibercept treatment benefit for both bevacizumab-pretreated and bevacizumab-naïve patients in the strictly second-line setting although no definitive conclusion may be inferred. The benefit associated with the addition of aflibercept to second-line FOLFIRI in patients with mCRC was observed whatever the timing of first-line disease progression. There were no unexpected safety concerns.

Association of T-cell infiltration assessed in pretherapeutic biopsies (PTB) of patients with locally advanced rectal adenocarcinoma (LARC) with tumor response and relapse after chemoradiotherapy (CRT) and rectal surgery

3599

Background: Pre-operative CRT followed by total mesorectal excision (TME) is nowadays the standard of care for patient with LARC (cT3-T4N0 or cTxN+). Currently, pathologic complete response occurs in +/- 15% after CRT. Colorectal cancer T-cell infiltration is a strong prognostic factor for survival after primary tumor resection. Our aim was to determine whether T-cell infiltration in PTB could be predictive of tumor response and relapse after CRT + TME. Methods: Between 1999 and 2012, patients with LARC who underwent CRT + TME and with available clinical follow-up and PTB (with sufficient tumor cells density) were identified at the Cliniques universitaires St-Luc. The density of CD3 (T cells) and CD8 (cytotoxic) was quantified on immunostained PTB slides and analyzed with a dedicated image analysis software on whole-slide imaging. Comparisons were made using the Wilcoxon-Mann-Whitney test. Cumulative disease-free survival (DFS) was performed using the Kaplan-Meier estimator and compared by log-rank tests. Cox regression we used for uni- and multi-variate analysis. P value of less than 0.05 was considered statistically significant. Results: 154 patients (sex ratio M/F 1.8; mean age 65 years-old; upper (20%), mid (29%) and low rectum (51%), synchronous metastases (11%)) were analyzed. High CD3 and CD8 PTB densities were significantly associated with a higher pathological response (Dworak 3-4) and lower ypTNM stage after CRT +TME (p < 0,05). Higher CD3 and CD8 PTB densities were associated with higher patient DFS (CD3: HR = 2,30 (CI95%:1,15-4,59) p = 0,02; CD8: HR = 1,95 (CI95%: 1,01-3,75) p = 0,04). These results were confirmed in uni and multivariate analysis. CD3 and CD8 PTB densities added to pathological response (ypTNM/Dworak) but also clinical response (ycTNM) after CRT + TME increases significantly the accuracy prediction of tumor relapse. Conclusions: Pretherapeutic T-cell infiltration of LARC is predictive of tumor response and relapse after CRT +TME. This biomarker could be helpful for patient treatment decision. It must be validated in larger patient cohorts.

Radiological imaging markers predicting clinical outcome in patients with metastatic colorectal carcinoma treated with regorafenib: post hoc analysis of the CORRECT phase III trial (RadioCORRECT study)

OBJECTIVE

To identify imaging markers predicting clinical outcomes to regorafenib in metastatic colorectal carcinoma (mCRC).

METHODS

The RadioCORRECT study is a post hoc analysis of a cohort of patients with mCRC treated within the phase III placebo-controlled CORRECT trial of regorafenib. Baseline and week 8 contrast-enhanced CT were used to assess response by RECIST 1.1, changes in the sum of target lesion diameters (ΔSTL), lung metastases cavitation and liver metastases density. Primary and secondary objectives were to develop ex novo univariable and multivariable models to predict overall survival (OS) and progression-free survival (PFS), respectively.

RESULTS

202 patients were enrolled, 134 (66.3%) treated with regorafenib and 68 (33.7%) with placebo. In the univariate analysis, PFS predictors were lung metastases cavitation at baseline (HR 0.50, 95% CI 0.27 to 0.92, p=0.03) and at week 8 (HR 0.58, 95% CI 0.36 to 0.93, p=0.02). Baseline cavitation (HR 0.23, 95% CI 0.08 to 0.66, p=0.007), RECIST 1.1 (HR 0.23, 95% CI 0.14 to 0.4, p <0.0001) and ΔSTL (HR 1.16, 95% CI 1.06 to 1.27, p=0.002) predicted OS. We found an increase of 9% of diameter as the best threshold for discriminating OS (HR 2.64, 95% CI 1.61 to 4.34, p <0.001). In the multivariate analysis, baseline and week 8 cavitation remained significant PFS predictors. Baseline cavitation, RECIST 1.1 and ΔSTL remained predictors of OS in exploratory multivariable models. Assessment of liver metastases density did not predict clinical outcome.

CONCLUSIONS

RECIST 1.1 and ΔSTL predict favourable outcome to regorafenib. In contrast to liver metastases density that failed to be a predictor, lung metastases cavitation represents a novel radiological marker of favourable outcome that deserves consideration.

Regorafenib induced severe toxic hepatitis: characterization and discussion

BACKGROUND

Regorafenib is the first small-molecule multikinase inhibitor which showed survival benefits in pretreated metastatic colorectal cancer (mCRC) patients. Besides classical adverse events of this drug class, hepatotoxicity has been described as a frequent side effect.

MATERIAL AND METHODS

Patients with refractory mCRC treated with regorafenib in our institution were reviewed. Severe treatment-related liver toxicity was investigated. Clinical history, liver histology and genetic assessment (sequence analysis) of cytochrome P3A4 (CYP3A4) and uridine diphosphate-glucuronosyltransferase 1A9 (UGT1A9) involved in regorafenib metabolization were here reported for patients with severe hepatotoxicity.

RESULTS

Among the 93 reviewed patients, 3 presented severe and icteric toxic hepatitis which was fatal for 1 patient. Histopathological liver lesions were different depending on the onset of hepatotoxicity (acute or subacute): acinar zone 3 necrosis in case of acute symptoms, and portal tract inflammation with porto-central bridging and fibrosis in the delayed presentation. None of the patients had CYP3A4 gene mutations. Similar polymorphisms in UGT1A9 gene promoter region (UGT1A9 variant -118T_9>10 [rs3832043]) were found in both patients who presented acute hepatitis. Moreover, it appears retrospectively that both of them already experienced significant toxicity under irinotecan-based chemotherapy.

CONCLUSION

This is the first report of severe hepatotoxicity with available liver histology and genetic assessment of enzymes involved in regorafenib metabolization. This report also reminds the importance of close liver tests monitoring during regorafenib treatment.

Lymph node ratio and surgical quality are strong prognostic factors of rectal cancer: results from a single referral centre

AIM

Nodal stage is a strong prognostic factor of oncological outcome of rectal cancer. To compensate for the variation in total number of harvested nodes, calculation of the lymph node ratio (LNR) has been advocated. The aim of the study was to compare the impact, on the long-term oncological outcome, of the LNR with other predictive factors, including the quality of total mesorectal excision (TME) and the state of the circumferential resection margin.

METHOD

Consecutive patients having elective surgery for nonmetastatic rectal cancer were extracted from a prospectively maintained database. Retrospective uni- and multivariate analyses were performed based on patient-, surgical- and tumour-related factors. The prognostic value of the LNR on overall survival (OS) and on overall recurrence-free survival (ORFS) was assessed and a cut-off value was determined.

RESULTS

From 1998 to 2013, out of 456 patients, 357 with nonmetastatic disease were operated on for rectal cancer. Neoadjuvant radiochemotherapy was administered to 66.7% of the patients. The mean number of lymph nodes retrieved was 12.8 ± 8.78 per surgical specimen. A lower lymph node yield was obtained in patients who received neoadjuvant chemoradiotherapy (11.8 vs 14.2; P = 0.014). The 5-year ORFS was 71.8% and the 5-year OS was 80.1%. Multivariate analysis confirmed LNR, the quality of TME and age to be independent prognostic factors of OS. LNR, age and perineural infiltration were independently associated with ORFS. Low- and high-risk patients could be discriminated using an LNR cut-off value of 0.2.

CONCLUSION

LNR is an independent prognostic factor of OS and ORFS. In line with the principles of optimal surgical management, the quality of TME and lymph node yield are essential technical requirements.

Prospective Evaluation of First-Line Erlotinib in Advanced Non-Small Cell Lung Cancer (NSCLC) Carrying an Activating EGFR Mutation: A Multicenter Academic Phase II Study in Caucasian Patients (FIELT)

Introduction

Epidermal Growth Factor Receptor (EGFR) tyrosine kinase inhibition is the preferred first-line treatment of advanced adenocarcinoma of the lung that harbors EGFR activating tyrosine kinase domain mutations. Most data available pertain to Asian populations in which such mutations are more prevalent. We report on the long-term results of first-line treatment with erlotinib in Caucasian patients with advanced adenocarcinoma of the lung that have a somatic EGFR mutation in their tumor.

Methods

Multicenter academic prospective phase II study with erlotinib in patients with an activating EGFR tyrosine kinase (TK) domain somatic mutation (any exon encoding the kinase domain) in the tumor and no prior treatment for their advanced disease.

Results

Phenotypic preselecting of 229 patients led to a high EGFR mutation detection rate of 24% of which 46 patients were included in the phase II study. With a progression free survival (PFS) of 81% at three months the study met its primary endpoint for presumed superiority over chemotherapy. With an overall median PFS of 11 months and a median overall survival (OS) of 23 months, the results compare favorably with results obtained in randomized studies using TKI in first line in EGFR mutation positive adenocarcinoma of the lung.

Conclusion

The present study reinforces the use of EGFR tyrosine kinase inhibition (TKI) as a first line treatment of choice for advanced adenocarcinoma of the lung carrying an activating EGFR mutation. The mutation rate in preselected Caucasian patients is higher than previously reported. Issues relevant for clinical practice are discussed.

Trial Registration

ClinicalTrials.gov NCT00339586

Ossification of a rectal tumor: an uncommon finding

The authors report the case of a 29-year-old woman with partially calcified stage cT4N2M0 mucoid adenocarcinoma of the mid-rectum. Concomitant neoadjuvant chemoradiotherapy was administered. Preoperative CT scan and MRI demonstrated stable disease with a marked increase of its mineralized component. Histology confirmed a mucoid adenocarcinoma with ossified matrix. Osteocytes were identified in the tumor. TNM (5th edition) staging was ypT3N2M1. This case illustrates heterotopic ossification of a rectal tumor, a fairly uncommon finding. The mechanism of heterotopic bone formation within gastrointestinal adenocarcinoma has not been fully elucidated. The impact of this particular feature on patient outcome is unknown.

Analysis of circulating DNA and protein biomarkers to predict the clinical activity of regorafenib and assess prognosis in patients with metastatic colorectal cancer: a retrospective, exploratory analysis of the CORRECT trial

BACKGROUND

Tumour mutational status is an important determinant of the response of metastatic colorectal cancer to targeted treatments. However, the genotype of the tissue obtained at the time of diagnosis might not accurately represent tumour genotype after multiple lines of treatment. This retrospective exploratory analysis investigated the clinical activity of regorafenib in biomarker subgroups of the CORRECT study population defined by tumour mutational status or plasma protein levels.

METHODS

We used BEAMing technology to identify KRAS, PIK3CA, and BRAF mutations in DNA obtained from the plasma of 503 patients with metastatic colorectal cancer who enrolled in the CORRECT trial. We quantified total human genomic DNA isolated from plasma samples for 503 patients using a modified version of human long interspersed nuclear element-1 (LINE-1) quantitive real-time PCR. We also measured the concentration of 15 proteins of interest-angiopoietin 2, interleukin 6, interleukin 8, placental growth factor, soluble TIE-1, soluble VEGFR1, VEGF-A, VEGF-C, VEGF-D, VEGF-A isoform 121, bone morphogenetic protein 7, macrophage colony-stimulating factor, stromal cell-derived factor-1, tissue inhibitor of metalloproteinase 2, and von Willebrand factor-in plasma samples from 611 patients. We did correlative analyses of overall survival and progression-free survival in patient subgroups based on mutational status, circulating DNA concentration, and protein concentrations. The CORRECT trial was registered with ClinicalTrials.gov, number NCT01103323.

FINDINGS

Tumour-associated mutations were readily detected with BEAMing of plasma DNA, with KRAS mutations identified in 349 (69%) of 503 patients, PIK3CA mutations in 84 (17%) of 503 patients, and BRAF mutations in 17 (3%) of 502 patients. We did not do correlative analysis based on BRAF genotype because of the low mutational frequency detected for this gene. Some of the most prevalent individual hot-spot mutations we identified included: KRAS (KRAS G12D, 116 [28%] of 413 mutations; G12V, 72 [17%]; and G13D, 67 [16%]) and PIK3CA (PIK3CA E542K, 27 [30%] of 89 mutations; E545K, 37 [42%]; and H1047R, 12 [14%]). 41 (48%) of 86 patients who had received anti-EGFR therapy and whose archival tumour tissue DNA was KRAS wild-type in BEAMing analysis were identified as having KRAS mutations in BEAMing analysis of fresh plasma DNA. Correlative analyses suggest a clinical benefit favouring regorafenib across patient subgroups defined by KRAS and PIK3CA mutational status (progression-free survival with regorafenib vs placebo: hazard ratio [HR] 0·52, 95% CI 0·35-0·76 for KRAS wild-type; HR 0·51, 95% CI 0·40-0·65 for KRAS mutant [KRAS wild type vs mutant, pinteraction=0·74]; HR 0·50, 95% CI 0·40-0·63 for PIK3CA wild-type; HR 0·54, 95% CI 0·32-0·89 for PIK3CA mutant [PIK3CA wild-type vs mutant, pinteraction=0·85]) or circulating DNA concentration (progression-free survival with regorafenib vs placebo: HR 0·53, 95% CI 0·40-0·71, for low circulating DNA concentrations; HR 0·52, 95% CI 0·40-0·70, for high circulating DNA concentrations; low vs high circulating DNA, pinteraction=0·601). With the exception of von Willebrand factor, assessed with the median cutoff method, plasma protein concentrations were also not associated with regorafenib activity in terms of progression-free survival. In univariable analyses, the only plasma protein that was associated with overall survival was TIE-1, high concentrations of which were associated with longer overall survival compared with low TIE-1 concentrations. This association was not significant in multivariable analyses.

INTERPRETATION

BEAMing of circulating DNA could be a viable approach for non-invasive analysis of tumour genotype in real time and for the identification of potentially clinically relevant mutations that are not detected in archival tissue. Additionally, the results show that regorafenib seems to be consistently associated with a clinical benefit in a range of patient subgroups based on mutational status and protein biomarker concentrations.

FUNDING

Bayer HealthCare Pharmaceuticals.

Randomized phase II studies comparing pathological responses observed on colorectal cancer metastases resected after preoperative treatment combining bevacizumab or cetuximab with FOLFOX or FOLFIRI

TPS795

Background: Even if the use of targeted therapies combined with chemotherapy has demonstrated increase response rate and survival benefit in non resectable metastatic colorectal cancer (mCRC), the administration of these combinations in frontline resectable disease is source of debate and optimal association is still unclear. Based on a retrospective analysis, we previously reported thatthe chemotherapy partner combined with VEGF or EGFR inhibitors influenced pathological responses (pR) on the resected colorectal cancer metastases (CRCM) with a significant advantage for oxaliplatin with anti-VEGF or irinotecan with anti-EGFR combinations. We aimed to design 2 parallel studies (BEV-ONCO, CET-ONCO) to prospectively precise optimal combination between oxaliplatin and irinotecan with bevacizumab or cetuximab before CRCM resection. Methods: The 2 studies are open label randomized multi-centric trials and concern mCRC patients with resectable disease in whom a preoperative treatment is considered. The primary objective is to assess the CRCM pR rate according the Tumor Regression Grade classification (Rubbia-Brandt) after allocated preoperative treatment (bevacizumab combined with FOLFOX vs. FOLFIRI without consideration of RAS/BRAF for BEV-ONCO trial (EUDRACT 2012-005376-34) and cetuximab associated with FOLFOX or FOLFIRI only for RAS/BRAF wild type tumor for CET-ONCO trial (EUDRACT 2012-005249-19)). According investigator’s choice, patient will received 3 to 6 treatment cycles before CRCM resection. Patient’s survival, safety, surgical complications and treatment associated liver-toxicity are secondary end-points. Up to 60 patients (30 per treatment group) will be randomised in each study (power: 80%, type I error of 5% to detect a difference in proportion of pR rate between FOLFOX or FOLFIRI association of 0.40). Formal comparison will not be done across studies. Translational research projects are ongoing (CRCM immune response, tumour specific genetic rearrangements as new specific biomarkers). Clinical trial information: NCT01858649 (BEV-ONCO); NCT01858662 (CET-ONCO). Clinical trial information: NCT01858649 (BEVONCO) NCT01858662 (CETONCO).

Subgroup analysis of patients with metastatic colorectal cancer (mCRC) treated with regorafenib (REG) in the CORRECT trial who had progression-free survival (PFS) longer than 4 months

710

Background: In the CORRECT phase III trial (NCT01103323), the multikinase inhibitor REG significantly improved overall survival (OS) and PFS vs placebo in patients with mCRC who had disease progression after other standard therapies (HR for OS: 0.77; 1-sided p =0.0052; Grothey 2013). A post-hoc exploratory subgroup analysis was conducted to evaluate patients in the REG treatment group who had a PFS longer than 4 months (long-PFS) defined as patients who progressed, died, or discontinued treatment for other reasons after 4 months. Methods: Of the505 patients randomized to REG in CORRECT, 98 (19.4%) were classified as having a long-PFS benefit. Baseline characteristics, safety, and dosing parameters were analyzed descriptively. Results: The long-PFS subpopulation was representative of the overall study population (Table). Long-PFS patients received a median of 6 cycles of REG (1-12), 92% received ≥5 cycles, and 20% had > 8 cycles. Overall 34% of patients had dose reductions and 87% had dose interruptions. The actual mean daily dose was 139 mg and the mean percent of the planned dose was 81%. Adverse events (AE) of any grade were experienced by all long-PFS patients, and the most common grade ≥3 AEs were hand-foot skin reaction (20%), hypertension (17%), diarrhea (17%), and fatigue (16%). Conclusions: A subset of 98 (19.4%) patients treated with REG in the CORRECT study had a PFS > 4 months, confirming the clinical benefit and tolerability of REG as a treatment option for patients with mCRC. Prospective validation of these findings in conjunction with biomarker analysis from real-life clinical experience is needed. Clinical trial information: NCT01103323. [Table: see text]

Preoperative treatment to modify the immune microenvironnement of liver colorectal metastases

602

Background: We previously reported that an adaptive Th1 immune response (CD3/CD8/CD45RO T-cells) observed in resected primary colorectal tumor and liver colorectal metastases (LCM) is an important prognostic factor. B and FoxP3 regulatory lymphocytes participate to the modulation of this response. We aimed to investigate whether the preoperative treatments influenced the quality and the density of the immune infiltrates previously reported in the LCM. Methods: We used a cohort of metastatic colorectal patients (n=107) engaged for curative liver surgery with available FFPE blocks for all resected LCM to confirm the prognostic impact of the immune response. Among this cohort of 338 LCMs, 46 were completely resected after chemotherapy (CT) alone, 130 after CT + anti-VEGF, 118 after CT + anti-EGFR and 44 after surgery alone. LCMs were analyzed for histological response according the Tumor Regression Grade (TRG) and regrouped as Response (R, TRG1-3) or No Response (NR, TRG4-5). The density of CD3+ (T-cells), CD8+ (cytotoxic), CD45RO+ (memory), CD20+ (B-cells) and FoxP3+ (regulatory) in the core (CT) and invasive margin (IM) of all LCM was quantified on immunostained slides. The mean density value (CT/IM) was calculated for each marker with a dedicated image analysis software on whole-slide imaging. Comparisons were made using the Wilcoxon-Mann-Whitney test. Results: LCMs showing R (compared to NR and untreated LCM) were more frequently associated with a high immune infiltrate for CD3+ (CT: p<0.005; IM: p<0.05), CD8+ (CT: p<0.005; IM: p<0.005) and CD20+ (CT: p<0.05). Conversely, high FoxP3+ density in the CT and IM was related to NR and untreated LCMs (p<0.01). LCMs treated with an anti-EGFR therapy showed higher densities of CD3+ (CT: p<0.005; IM: p<0.01), CD8+ (CT: p<0.005), CD45RO+ (CT: p<0.005), CD20+ (CT: p<0.005) and FoxP3+ (CT: p<0.05; IM: p<0.005) compared to other treatments and untreated LCMs. Conclusions: Preoperative treatment modifies the LCM immune microenvironnement. LCMs with a histological response show a cytotoxic immune response (CD3+/CD8+) with associated B-cells (CD20+) and downregulated Tregs (FoxP3+). The use of an anti-EGFR therapy significantly increases immune infiltration in the CT.

Final results from PRIME: randomized phase III study of panitumumab with FOLFOX4 for first-line treatment of metastatic colorectal cancer

BACKGROUND

The Panitumumab Randomized trial In combination with chemotherapy for Metastatic colorectal cancer to determine Efficacy (PRIME) demonstrated that panitumumab-FOLFOX4 significantly improved progression-free survival (PFS) versus FOLFOX4 as first-line treatment of wild-type (WT) KRAS metastatic colorectal cancer (mCRC), the primary end point of the study.

PATIENTS AND METHODS

Patients were randomized 1:1 to panitumumab 6.0 mg/kg every 2 weeks + FOLFOX4 (arm 1) or FOLFOX4 (arm 2). This prespecified final descriptive analysis of efficacy and safety was planned for 30 months after the last patient was enrolled.

RESULTS

A total of 1183 patients were randomized. Median PFS for WT KRAS mCRC was 10.0 months [95% confidence interval (CI) 9.3-11.4 months] for arm 1 and 8.6 months (95% CI 7.5-9.5 months) for arm 2; hazard ratio (HR) = 0.80; 95% CI 0.67-0.95; P = 0.01. Median overall survival (OS) for WT KRAS mCRC was 23.9 months (95% CI 20.3-27.7 months) for arm 1 and 19.7 months (95% CI 17.6-22.7 months) for arm 2; HR = 0.88; 95% CI 0.73-1.06; P = 0.17 (68% OS events). An exploratory analysis of updated survival (>80% OS events) was carried out which demonstrated improvement in OS; HR = 0.83; 95% CI 0.70-0.98; P = 0.03 for WT KRAS mCRC. The adverse event profile was consistent with the primary analysis.

CONCLUSIONS

In WT KRAS mCRC, PFS was improved, objective response was higher, and there was a trend toward improved OS with panitumumab-FOLFOX4, with significant improvement in OS observed in an updated analysis of survival in patients with WT KRAS mCRC treated with panitumumab + FOLFOX4 versus FOLFOX4 alone (P = 0.03). These data support a positive benefit-risk profile for panitumumab-FOLFOX4 for patients with previously untreated WT KRAS mCRC. KRAS testing is critical to select appropriate patients for treatment with panitumumab.

Sinusoidal obstruction syndrome (SOS) related to chemotherapy for colorectal liver metastases: factors predictive of severe SOS lesions and protective effect of bevacizumab

OBJECTIVES

The most frequent presentation of chemotherapy-related toxicity in colorectal liver metastases (CRLM) is sinusoidal obstruction syndrome (SOS). The purpose of the present study was to identify preoperative factors predictive of SOS and to establish associations between type of chemotherapy and severity of SOS.

METHODS

A retrospective study was carried out in a tertiary academic referral hospital. Patients suffering from CRLM who had undergone resection of at least one liver segment were included. Grading of SOS on the non-tumoral liver parenchyma was accomplished according to the Rubbia-Brandt criteria. A total of 151 patients were enrolled and divided into four groups according to the severity of SOS (grades 0-3).

RESULTS

Multivariate analysis identified oxaliplatin and 5-fluorouracil as chemotherapeutic agents responsible for severe SOS lesions (P < 0.001 and P = 0.005, respectively). Bevacizumab was identified as having a protective effect against the occurrence of SOS lesions (P = 0.005). Univariate analysis identified the score on the aspartate aminotransferase : platelets ratio index (APRI) as the most significant biological factor predictive of severe SOS lesions. Splenomegaly is also significantly associated with the occurrence of severe SOS lesions.

CONCLUSIONS

The APRI score and splenomegaly are effective as factors predictive of SOS. Bevacizumab has a protective effect against SOS.

Panitumumab-FOLFOX4 treatment and RAS mutations in colorectal cancer

BACKGROUND

Patients with metastatic colorectal cancer that harbors KRAS mutations in exon 2 do not benefit from anti-epidermal growth factor receptor (EGFR) therapy. Other activating RAS mutations may also be negative predictive biomarkers for anti-EGFR therapy.

METHODS

In this prospective-retrospective analysis, we assessed the efficacy and safety of panitumumab plus oxaliplatin, fluorouracil, and leucovorin (FOLFOX4) as compared with FOLFOX4 alone, according to RAS (KRAS or NRAS) or BRAF mutation status. A total of 639 patients who had metastatic colorectal cancer without KRAS mutations in exon 2 had results for at least one of the following: KRAS exon 3 or 4; NRAS exon 2, 3, or 4; or BRAF exon 15. The overall rate of ascertainment of RAS status was 90%.

RESULTS

Among 512 patients without RAS mutations, progression-free survival was 10.1 months with panitumumab-FOLFOX4 versus 7.9 months with FOLFOX4 alone (hazard ratio for progression or death with combination therapy, 0.72; 95% confidence interval [CI], 0.58 to 0.90; P=0.004). Overall survival was 26.0 months in the panitumumab-FOLFOX4 group versus 20.2 months in the FOLFOX4-alone group (hazard ratio for death, 0.78; 95% CI, 0.62 to 0.99; P=0.04). A total of 108 patients (17%) with nonmutated KRAS exon 2 had other RAS mutations. These mutations were associated with inferior progression-free survival and overall survival with panitumumab-FOLFOX4 treatment, which was consistent with the findings in patients with KRAS mutations in exon 2. BRAF mutations were a negative prognostic factor. No new safety signals were identified.

CONCLUSIONS

Additional RAS mutations predicted a lack of response in patients who received panitumumab-FOLFOX4. In patients who had metastatic colorectal cancer without RAS mutations, improvements in overall survival were observed with panitumumab-FOLFOX4 therapy. (Funded by Amgen and others; PRIME ClinicalTrials.gov number, NCT00364013.).

Overall survival (OS) analysis from PRIME: Randomized phase III study of panitumumab (pmab) with FOLFOX4 for first-line metastatic colorectal cancer (mCRC)

3620

Background: The primary and final analyses of PRIME demonstrated that pmab + FOLFOX4 significantly improved progression-free survival (PFS) vs FOLFOX4 alone for first-line treatment of patients (pts) with wild-type (WT) KRAS exon 2 mCRC. Methods: Pts were randomized 1:1 to pmab 6.0 mg/kg every 2 weeks + FOLFOX4 or FOLFOX4 alone and had no prior chemotherapy for mCRC, ECOG performance status ≤ 2, and tumor tissue for biomarker testing. The primary endpoint was PFS by central assessment. Secondary endpoints included OS, objective response rate, and safety. KRAS exon 2 tumor status was determined by a blinded central lab prior to the primary analysis. This exploratory analysis of updated survival (>80% OS events) estimated the treatment effect of pmab + FOLFOX4 compared with FOLFOX4 alone on OS by KRAS exon 2 status. Previous analyses in pts with WT KRAS exon 2 tumor status reported OS with an event rate of 54% of pts in the primary analysis and 68% of pts in the final analysis. Results: 1183 pts were randomized and received treatment: 593 pts in the pmab + FOLFOX4 arm and 590 pts in the FOLFOX4 alone arm. The KRAS exon 2 ascertainment rate was 93%, consistent with the primary analysis. 535/656 pts (82%) with WT KRAS exon 2 mCRC had an OS event at the time of this analysis. Results are shown (Table). Conclusions: In this updated analysis, an improvement in OS was observed in pts with WT KRAS exon 2 mCRC treated with pmab + FOLFOX4 vs FOLFOX4 alone (p = 0.03). Median OS was reduced in pts with mutant (MT) KRAS mCRC (p = 0.16) and is consistent with previous analyses. Updated efficacy and safety results will be presented. KRAS testing is critical to select appropriate pts with mCRC for treatment with pmab. Clinical trial information: NCT00364013. [Table: see text]

Analysis of plasma protein biomarkers from the CORRECT phase III study of regorafenib for metastatic colorectal cancer

3514

Background: In the CORRECT phase III trial, the multikinase inhibitor regorafenib (REG) demonstrated significant improvement in overall survival (OS) and progression-free survival (PFS) vs placebo (Pla) in patients with metastatic colorectal cancer (mCRC) whose disease had progressed on other standard therapies. An exploratory biomarker subanalysis was conducted to identify protein biomarkers with potential predictive or prognostic value. Methods: Fifteen proteins of interest, many of which are involved in angiogenesis, were quantified by multiplex immunoassay or ELISA in baseline plasma samples collected at study entry from 80% (611/760) of patients. Potential predictive and prognostic effects were evaluated. Results: The biomarker subpopulation was representative of the overall study population in terms of OS and PFS. Using OS as the clinical endpoint, Tie-1 was the only protein whose level demonstrated significant correlation with efficacy (low protein group: REG/Pla, HR 0.87; high protein group, HR 0.56; interaction, p=0.035). Using PFS as the clinical endpoint, von Willebrand factor (VWF) was the only protein whose level demonstrated significant correlation with efficacy (low protein group: REG/Pla, HR 0.39; high protein group, HR 0.60; interaction, p=0.02). Following correction for multiple testing, neither Tie-1 nor VWF data retained statistical significance. Baseline levels of IL-8 and placental growth factor (PlGF) were found to have prognostic value for OS (IL-8: high/low protein levels, HR 3.48, p<0.001; PIGF: HR 1.81, p=0.002). IL-8 was also prognostic for PFS (high/low protein levels: HR 1.63, p<0.001). Conclusions: None of the plasma proteins examined showed significant predictive value for REG efficacy after multiple testing correction. The association between baseline levels of Tie-1/VWF and REG efficacy may be a hypothesis to be tested in further trials. Clinical trial information: NCT01103323.

Analysis of KRAS/NRAS and BRAF mutations in the phase III PRIME study of panitumumab (pmab) plus FOLFOX versus FOLFOX as first-line treatment (tx) for metastatic colorectal cancer (mCRC)

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Background: Analysis of a phase III pmab monotherapy study indicated that KRAS and NRAS mutations beyond KRAS exon 2 may be predictive of pmab efficacy (Peeters et al, 2013). Methods: The primary objective of this prospectively defined retrospective analysis of PRIME was to assess the effect of pmab + FOLFOX vs FOLFOX on overall survival (OS) in pts with mCRC based on RAS (KRAS or NRAS) or BRAF mutation status. "Gold standard" bidirectional Sanger sequencing and WAVE-based SURVEYOR Scan Kits from Transgenomic (conducted independently) were used to detect mutations in KRAS exon 3, exon 4; NRAS exon 2, exon 3, exon 4; and BRAF exon 15. Results: RAS ascertainment rate was 90%. Tx HRs for pts with WT RAS were 0.78 (95% CI, 0.62 - 0.99; p = 0.04) for OS (median gain of 5.8 months in the pmab arm) and 0.72 (95% CI, 0.58 - 0.90; p = < 0.01) for PFS. Tx HRs for WT KRAS exon 2/mutant (MT) other RAS were 1.29 (95% CI, 0.79 - 2.10; p = 0.31) for OS and 1.28 (95% CI, 0.79 - 2.07; p = 0.32) for PFS. Tx HRs for pts with WT or MT BRAF were inconsistent with a predictive biomarker (Table). Prognostic effects of the tested biomarkers will be presented. Conclusions: A statistically significant OS benefit was observed in pts with WT RAS mCRC treated with pmab + FOLFOX vs FOLFOX. Pmab is unlikely to benefit pts with any RAS mutations. In this analysis, BRAF mutation had no predictive value. Clinical trial information: NCT00364013. [Table: see text]

Time profile of adverse events (AEs) from regorafenib (REG) treatment for metastatic colorectal cancer (mCRC) in the phase III CORRECT study

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Background: In the CORRECT phase III trial, the multikinase inhibitor REG demonstrated significant improvement in overall survival and progression-free survival vs placebo (P) in patients with mCRC whose disease had progressed on other standard therapies. The most frequent grade 3 AEs were hand–foot skin reaction (HFSR), fatigue, diarrhea, hypertension, and rash. We examined when these AEs first occurred and what impact they had on REG dosing. Methods: Adults with mCRC progressing after all standard therapies were randomized to receive REG 160 mg (n=505) or P (n=255) orally once daily for the first 3 weeks of each 4-week cycle. AEs were managed with dose modifications (reduction and interruption) according to the protocol. Results: The safety population comprised 753 pts (REG n=500, P n=253). The mean ± SD treatment duration was 12.1 ± 9.7 weeks for REG and 7.8 ± 5.2 weeks for P. Treatment-emergent AEs occurred in 99.6% of REG pts and 96.8% of P pts. AEs occurring in ≥10% more REG than P pts were fatigue, HFSR, anorexia, diarrhea, weight loss, voice changes, hypertension, rash/desquamation, oral mucositis, fever, hyperbilirubinemia, and low platelet count. The incidence of grade ≥3 HFSR, fatigue, hypertension, and rash/desquamation typically peaked in cycle 1 and tapered to a relatively stable lower incidence over later cycles, while the incidence of diarrhea remained relatively constant throughout the study; median time to first occurrence and worst grade of these AEs is shown in the table. AEs led to dose modifications in 66.6% of REG pts and 22.5% of P pts. Conclusions: The most common AEs in the REG group typically occurred early during treatment. Close early monitoring of AEs and proper management by dose modification is recommended. Clinical trial information: NCT01103323. [Table: see text]

Regorafenib (REG) in progressive metastatic colorectal cancer (mCRC): Analysis of age subgroups in the phase III CORRECT trial

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Background: In the CORRECT phase III trial, the multikinase inhibitor REG demonstrated significant improvement in overall survival (OS) and progression-free survival vs placebo (Pla) in patients (pts) with mCRC whose disease progressed on other standard therapies. The most frequent REG-related grade ≥3 adverse events (AEs) of interest were hand–foot skin reaction (HFSR), fatigue, diarrhea, hypertension, and rash/desquamation. We explored whether the impact of REG in pts aged ≥65 years differed from that in younger patients. Methods: Pts with mCRC progressing following all other available therapies were randomized 2:1 to receive REG 160 mg once daily (n=505) or Pla (n=255) for the first 3 weeks of each 4-week cycle. The dose could be modified to manage AEs. The primary endpoint was OS. We report efficacy, safety, and dosing data from REG recipients by age. Results: The REG treatment group included 309 pts <65 years (307 evaluable for safety) and 196 pts ≥65 years (193 evaluable for safety). The OS hazard ratio (REG/Pla) was 0.72 (95% confidence interval [CI] 0.56–0.91) in pts <65 years and 0.86 (95% CI 0.61–1.19) in pts ≥65 years (interaction p-value = 0.405). Median OS was 6.7 vs 5 months for REG vs Pla in pts <65 years, and 6.0 vs 5.6 months, respectively, in pts ≥65 years. Most pts experienced drug-related AEs (<65 years: 93.8%; ≥65 years: 91.7%). The rates of grade ≥3 REG-related AEs of interest and dose modifications are shown in the Table. In pts <65 years vs ≥65 years, median (interquartile range [IQR]) duration of REG was 7.6 weeks (6.6–15.4) vs 7.1 weeks (5.1–17.2), median (IQR) daily REG dose was 160.0 mg (134.6–160.0) vs 160.0 mg (137.5–160.0), and median (IQR) proportion of planned REG dose was 83.3% (65.7–100.0) vs 78.6% (66.7–100.0), respectively. Conclusions: In the CORRECT trial, REG demonstrated an OS benefit in pts <65 years and ≥65 years. Safety and tolerability of REG appeared to be similar in both age subgroups. Clinical trial information: NCT01103323. [Table: see text]

Comprehensive analysis of KRAS and NRAS mutations as predictive biomarkers for single agent panitumumab (pmab) response in a randomized, phase III metastatic colorectal cancer (mCRC) study (20020408)

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Background: An exploratory biomarker analysis of the randomized, phase 3 monotherapy 20020408 study of pmab vs best supportive care (BSC) demonstrated that mutations in KRAS exon 3 and NRAS exons 2 and 3 appeared to be predictive of pmab response (Peeters et al, 2013). We expanded these results to determine whether mutations in exon 4 of the KRAS and NRAS genes are predictive for pmab treatment and to determine the treatment effect in the overall wild-type (WT) KRAS and NRAS population. Methods: Using a combination of Next Generation Sequencing, Sanger Sequencing, and WAVE-based SURVEYOR Scan Kits from Transgenomic, archival patient tumors were examined for mutations in KRAS and NRAS exon 4. These data were combined with previously presented data from KRAS and NRAS exon 2 and 3 analyses for evaluation of the comprehensive WT KRAS and NRAS subgroup. Results: 9/243 (3.7%) and 2/243 (0.8%) patient tumors with WT KRAS exon 2 status harbored a mutation in KRAS or NRAS exon 4, respectively. One tumor had mutations in both KRAS and NRAS exon 4. In the pmab arm, patients with WT KRAS and WT NRAS tumor status had an objective response rate (ORR) of 15% (11/72) whereas patients with mutant (MT) KRAS or MT NRAS tumor status had an ORR of 1% (1/95; 1 patient with MT KRAS exon 4 had a partial response). There were no responses in the BSC arm regardless of the tumor status. In this analysis set, the treatment hazard ratio (HR; pmab:BSC) for progression-free survival (PFS) in the WT KRAS and WT NRAS subgroup was 0.38 (95% CI: 0.27 - 0.56), and in the MT KRAS or MT NRAS subgroup was 0.98 (95% CI: 0.73 - 1.31). The original WT KRAS exon 2 subgroup PFS HR was 0.45 (95% CI: 0.34 - 0.59) (Amado et al, 2007). Conclusions: This exploratory analysis suggests that mutations in KRAS and NRAS exon 4 occur in a small, but meaningful percentage of patients with mCRC. Extending previous findings from this study in patients with MT KRAS and/or MT NRAS exon 2 and/or 3 tumors, patients with MT KRAS and/or MT NRAS exon 4 tumors do not appear to benefit from pmab therapy. Clinical trial information: NCT00113763.

Randomised, placebo-controlled, double-blind, parallel-group phase III study evaluating aflibercept in patients receiving first-line treatment with gemcitabine for metastatic pancreatic cancer

BACKGROUND

This phase III study investigated the addition of aflibercept to gemcitabine, in patients with advanced pancreatic cancer.

PATIENTS AND METHODS

Patients with metastatic pancreatic cancer were randomly assigned to receive either intravenous (i.v.) aflibercept, 4 mg/kg every 2 weeks, or matching placebo combined with gemcitabine, 1000 mg/m(2) i.v. weekly for 7 weeks out of 8, then weekly for 3 weeks out of 4 until progressive disease, unacceptable toxicity or withdrawal of consent. The primary objective was to demonstrate an improvement in overall survival (OS) between the treatment arms.

RESULTS

The study was stopped for futility following a planned interim analysis of OS in 427 randomised patients. With a median follow-up of 7.9 months, based on the 546 patients at study termination, median OS was 7.8 months in the gemcitabine plus placebo arm (n=275) versus 6.5 months in the gemcitabine plus aflibercept arm (n=271), which was not significant (hazard ratio 1.165, 95% confidence interval (CI) 0.921-1.473, p=0.2034). Median progression-free survival was 3.7 months in both arms. Treatment discontinuations due to adverse events were more frequent in the aflibercept than in the placebo-containing arm (23% versus 12%).

CONCLUSION

Adding aflibercept to gemcitabine did not improve OS in patients with metastatic pancreatic cancer.