Association of K-ras mutational status and clinical outcomes in patients with metastatic colorectal cancer receiving panitumumab alone

Reduced-dose of doublet chemotherapy combined with anti-EGFR antibodies in vulnerable older patients with metastatic colorectal cancer: Data from the REVOLT study

OBJECTIVES

To assess the toxicity patterns and effectiveness of doublet chemotherapy when administered at reduced doses of 20% (FOLFOX or FOLFIRI) in combination with anti-EGFR antibodies (cetuximab or panitumumab) in old, vulnerable patients with metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

We performed a retrospective observational study of RAS and BRAF wild-type, vulnerable patients aged ≥70 years with previously untreated mCRC. The primary endpoint was safety, and secondary endpoints were overall response rate (ORR), progression-free survival (PFS), and overall survival (OS).

RESULTS

One hundred and eighteen patients were collected from 14 selected Italian centres. The median age was 75 (range, 70-85). Geriatric screening by G8 tool gave a score ≤ 14 in all patients. In total, 75 and 43 patients received FOLFOX or FOLFIRI, respectively, in combination with panitumumab (53%) or cetuximab (47%). The overall incidence of grade (G) 3-4 neutropenia was 11.8%, and for skin rash 11%. The most frequent adverse events were G1-2 skin rash (49.1%), G1-2 diarrhea (21.1%) and G1-2 nausea (17.7%). The ORR was 57.3%. Stable disease was observed in 29.1% of patients, with a disease control rate of 86.4%. With a median follow-up of 18 months, the median PFS was 10.0 months (95% confidence interval [CI]: 8.5-11.4), while the median OS was 18.0 months (95% CI: 16.0-19.9). No statistically significant difference was observed between the regimens in terms of ORR, PFS (p = 0.908), and OS (p = 0.832).

CONCLUSION

This study shows that with an appropriate design, including reduced doses, vulnerable older patients best tolerate chemotherapy when combined with anti-EGFR antibodies.

Management of BRAF-mutant metastatic colorectal cancer: a review of treatment options and evidence-based guidelines

BACKGROUND

Colorectal cancer (CRC) is still a leading cause of cancer-related deaths in the United States and worldwide, despite recent improvements in cancer management. CRC, like many malignancies, is a heterogeneous disease, with subtypes characterized by genetic alterations. One common mutation in CRC is in the BRAF gene (most commonly V600E substitution). This occurs in ∼10% of patients with metastatic CRC (mCRC) and is a marker of poor prognosis.

DESIGN

Herein, we review the clinical and translational literature on the role of the BRAF V600E mutation in the pathogenesis of mCRC, its mechanisms as a prognostic marker, and its potential utility as a predictive marker of treatment response. We then summarize the current evidence-based recommendations for management of BRAF V600E-mutated mCRC, with a focus on recent clinical research advances in this setting.

RESULTS

The current standard therapies for first-line treatment of BRAF-mutated mCRC are chemotherapy with bevacizumab as well as 5-fluorouracil, leucovorin, oxaliplatin, and irinotecan (FOLFOXIRI) plus bevacizumab in patients with a good performance status. Combination strategies involving mitogen-activated protein kinase (MAPK) pathway blockade have shown promising results for the treatment of patients with BRAF V600E-mutated mCRC. The Binimetinib, Encorafenib, And Cetuximab cOmbiNed to treat BRAF-mutant ColoRectal Cancer (BEACON CRC) study represents the largest study in this population to date and has given strong clinical evidence to support BRAF and epidermal growth factor receptor inhibition with the combination of encorafenib plus cetuximab.

CONCLUSIONS

The treatment of BRAF-mutated mCRC has evolved rapidly over the last several years. Recently, combination strategies involving MAPK pathway blockade have shown promising results in BRAF V600E-mutated mCRC, and other potential targets continue to be explored. In addition, a greater understanding of the role of BRAF V600E mutation in the pathogenesis of CRC should also continue to fuel advances in the management of patients with mCRC harboring this genetic aberration.

Biomarker testing and mutation prevalence in metastatic colorectal cancer patients in five European countries using a large oncology database

Background: The literature on biomarker testing for metastatic colorectal cancer (mCRC) in Europe is scarce. This study aimed to estimate the percentage of mCRC patients from five European countries tested for biomarkers over time. Materials & methods: An oncology database was retrospectively analyzed; evaluated biomarkers were RAS, BRAF and microsatellite instability (MSI). The patients were drug treated during 2018 and tested for relevant biomarkers in 2013-2018. Results: RAS testing was conducted in >90% of mCRC patients from 2014 onwards. BRAF testing increased from 31% of mCRC patients in 2013 to 67% in 2018. MSI testing increased from 10 to 41%. There was no notable trend over time for RAS and BRAF mutation or MSI-high prevalence. Conclusion: Biomarker testing among patients diagnosed with mCRC was increased over time. This study demonstrates the quick uptake of biomarker testing in clinical practice. These findings are significant as biomarker-based drugs are becoming more common.

Efficacy and safety of panitumumab in a cohort of patients with metastatic colorectal cancer in France: PANI OUEST, a post-EMA-approval descriptive study with a geriatric oncology focus

BACKGROUND/AIMS

The Bretagne-Pays de la Loire cancer observatory, an oncology network created by the French Ministry of Health, is specifically dedicated to assess the use of new targeted anticancer therapies in routine practice. In line with the French National Cancer III program, our cancer network set up a real-life cohort, which is independent of the pharmaceutical industry, for patients with colorectal cancer to monitor patient safety and quality of care and promote pharmacovigilance.

MATERIALS AND METHODS

Panitumumab monotherapy was assessed in 243 patients with wild-type Kirsten rat sarcoma who were treated for metastatic colorectal cancer (mCRC) between July 2008 and December 2010 after prior chemotherapy using oxaliplatine and irinotecan. This was a post-European medicine agency marketing (EMA-M) study Results: This study shed light on the best practices, strategic adaptations, clinical results (treatment objective responses, 13%; progression free survival, 2.99 months [2.73-3.15]; and overall survival, 6.8 months [5.49-8.38]) as well as expected or unexpected (grade 3 or 4: 11.5%) secondary effects in the phase IV panitumumab treatment of mCRC.

CONCLUSION

Our results are similar to those by Amado whose phase III study led to obtaining EMA-M for panitumumab and tend to confirm the antitumor activity of this antiepidermal growth factor receptor antibody in the treatment of mCRC. In addition, our results opened avenues to further assessment of panitumumab use as monotherapy as well as its benefit-risk ratio while taking into account the patients' general and clinical characteristics. In 2012, the French National Authority for Health appended these data to the panitumumab transparency committee report.

Evolution of RAS testing over time: factors influencing mutation rates in metastatic colorectal cancer patients

Aim: Correct identification of RAS gene variants is key for targeted treatment decisions in patients with metastatic colorectal cancer. Published RAS mutation rates differ and could be influenced by several factors including testing methods. This study aimed to describe the performance of laboratories to correctly identify RAS variants over time and to understand how RAS testing has evolved in Europe. Materials & methods: Misclassification and test failure rates were calculated and related to the used test methodology for 239 unique laboratories participating in external quality assessment for metastatic colorectal cancer between 2013 and 2018. In addition, 33 laboratories completed a survey aiming to obtain more details on their routine testing strategies, number of samples analyzed and RAS mutation rates between 2013 and 2017. Results: The mutation status was correctly analyzed in 96.1% (N = 5471) RAS and BRAF tests. A total of 4.6% (N = 2860) RAS tests included false-negative results. In 1.6% (N = 5562) RAS and BRAF tests, an analysis failure occurred. Misclassifications and technical failures both decreased between 2013 and 2018. The number of next-generation sequencing users increased from 6.9% (N = 130) in 2013 to 44.6% (N = 112) in 2018. Over time, more codons were included in the methodologies, yet 23.2% (N = 112) did not offer full RAS testing (exon 2, 3, 4) in 2018. Based on the survey the overall RAS mutation rate was estimated as 45.2% (N = 27,325). Conclusion: This is the largest observational study reporting RAS mutation rates to-date. There was no trend of RAS mutation rates over time despite having a clear shift to more sensitive tests and increased quality of testing.

Prevalence of BRAF gene mutation in samples of primary and metastatic colorectal cancer: A meta-analysis

INTRODUCTION

Understanding the prevalence and biology of BRAF gene can improve the treatment methods of cancerous patients. This study aims to estimate the prevalence of BRAF gene mutation in samples of primary and metastatic colorectal cancer using meta-analysis method.

METHODS

We searched PubMed, Scopus, ScienceDirect, Ovid and Google Scholar motor engine using MeSH terms of relevant keywords. During the screening phase, titles, abstracts and full texts were reviewed and risk of bias was assessed for all selected papers based on Newcastle-Ottawa Scale (NOS) checklist. The results of the primary studies were combined using meta-analysis.

RESULTS

Of 95 eligible studies entered into the meta-analysis, prevalence of BRAF gene mutation had been assessed among 19,484 primary tumour samples as well as 12,256 metastatic samples. The total prevalence of BRAF gene mutation among primary tumour samples was estimated as of 10.16% (8.09-12.22) in the world, 0.41% (0-1.89) in EMRO region, 10.06% (7.54-12.59) in EURO region, 10.33% (7.24-13.43) in SEARO region and 11.33% (7.29-15.37) in WPRO region. The pooled estimates for BRAF gene mutation in metastatic samples were 6.53% (5.09-7.96), 8.07% (5.57-10.56), 5.38% (3.75-7.02) and 5.55% (1.72-9.38) for all regions, EURO, WPRO and PAHO regions respectively.

CONCLUSION

Our results showed evidences of BRAF gene mutation in one-tenth of primary colorectal tumour samples in EURO, PAHO, SEARO and WPRO regions which was considerably higher than that of the EMRO region.

Molecular Markers in Sex Differences in Cancer

Cancer is one of the common causes of death with a high degree of mortality, worldwide. In many types of cancers, if not all, sex-biased disparities have been observed. In these cancers, an individual's sex has been shown to be one of the crucial factors underlying the incidence and mortality of cancer. Accumulating evidence suggests that differentially expressed genes and proteins may contribute to sex-biased differences in male and female cancers. Therefore, identification of these molecular differences is important for early diagnosis of cancer, prediction of cancer prognosis, and determination of response to specific therapies. In the present review, we summarize the differentially expressed genes and proteins in several cancers including bladder, colorectal, liver, lung, and non-small cell lung cancers as well as renal clear cell carcinoma, and head and neck squamous cell carcinoma. The sex-biased molecular differences were identified via proteomics, genomics, and big data analysis. The identified molecules represent potential candidates as sex-specific cancer biomarkers. Our study provides molecular insights into the impact of sex on cancers, suggesting strategies for sex-biased therapy against certain types of cancers.

Off-label use of common predictive biomarkers in gastrointestinal malignancies: a critical appraisal

The use of immunohistochemistry (IHC) as a companion diagnostic is an increasingly important part of the case workup by pathologists and is often central to clinical decision making. New predictive molecular markers are constantly sought for to improve treatment stratification parallel to drug development. Unfortunately, official biomarker guidelines lag behind, and pathologists are often left hesitating when medical oncologists request off-labelled biomarker testing. We performed a literature review of five commonly requested off-label IHC predictive biomarkers in gastrointestinal tract (GIT) malignancies: HER2, mismatch repair (MMR), PD-L1, BRAF V600E and ROS1. We found that HER2 amplification is rare and poorly associated to IHC overexpression in extracolonic and extragastric GIT cancers; however in KRAS wild type colorectal cancers, which fail conventional treatment, HER2 IHC may be useful and should be considered. For MMR testing, more evidence is needed to recommend reflex testing in GIT cancers for treatment purposes. MMR testing should not be discouraged in patients considered for second line checkpoint inhibitor therapy. With the exception of gastric tumors, PD-L1 IHC is a weak predictor of checkpoint inhibitor response in the GIT and should be replaced by MMR in this context. BRAF inhibitors showed activity in BRAF V600E mutated cholangiocarcinomas and pancreatic carcinomas in non-first line settings. ROS1 translocation is extremely rare and poorly correlated to ROS1 IHC expression in the GIT; currently there is no role for ROS1 IHC testing in GIT cancers. Overall, the predictive biomarker literature has grown exponentially, and official guidelines need to be updated more regularly to support pathologists’ testing decisions.

LncRNA and mRNA signatures associated with neoadjuvant chemoradiotherapy downstaging effects in rectal cancer

Radiotherapy plays a crucial role in combined treatment modality in local advanced rectal cancer (LARC). While neoadjuvant chemoradiotherapy responses were variable in LARC patients, so, it is important to identify genes that closely associated with short-term and long-term responses to radiotherapy. In this study, we profiled long noncoding RNAs (lncRNAs) and messenger RNAs (mRNAs) expression values of LARC patients with different neoadjuvant chemoradiotherapy downstaging depth score based on Agilent Arraystar Human LncRNA V3.0 Array(Agilent, CA). LncRNAs and mRNAs with aberrant expression values between the two groups of LARC patients were identified and lncRNA-miRNA-mRNA regulation network was also obtained through the combination of miRcode and miRTarBase database. Gene interaction network and module analysis of differential expression mRNAs contained in the lncRNA-miRNA-mRNA network identified five hub genes, including KRAS, PDPK1, PPP2R5C, PPP2R1B, and YES1, that should be closely associated with LARC's response to chemoradiotherapy. Besides, Kaplan-Meier analysis based on the Cyber Research Center (CRC) data set from The Cancer Genome Atlas indicated that aberrant expression of the five hub genes is significantly associated with CRC overall survival. In conclusion, we obtained several biomarkers that should be associated with neoadjuvant chemoradiotherapy response in LARC, which should be helpful for individual treatment and prognosis improvement.

FOLFIRI plus panitumumab in the treatment of wild-type KRAS and wild-type NRAS metastatic colorectal cancer

Background

The aim of this study was to investigate the efficacy and safety of first-line panitumumab plus folinic acid, 5-fluorouracil and irinotecan (FOLFIRI) in patients with wild-type KRAS and wild-type NRAS metastatic colorectal cancer (mCRC).

Methods

Patients with wild-type KRAS and wild-type NRAS mCRC presenting to the medical oncology department of the Okmeydani Training and Research Hospital in Istanbul, Turkey, between April 2014 and January 2018 were enrolled in this study.

Results

A total of 64 patients (35 males and 29 females) with a median age of 59 (35–81) years old were enrolled. The median follow-up was 18.9 months, and the median progression-free survival was 13 months. The median overall survival (OS) was 26 months in the patients with wild-type KRAS and wild-type NRAS mCRC. It was 90.4% for the 6-month OS, 79.5% for the 1-year OS, 53.7% for the 2-year OS and 31.1% for the 3-year OS. The median OS of the patients who underwent metastasectomies was 40 [95% confidence interval (CI) = 19.9–60.1] months, and the median OS of the patients without metastasectomies was 22 (95% CI = 17.7–26.4) months. There was a statistically significant difference between these (P = 0.007).

Conclusion

The first-line FOLFIRI plus panitumumab was associated with favourable efficacy in the patients with wild-type KRAS and wild-type NRAS mCRC, and it was well tolerated. The removal of the metastases that became resectable after chemotherapy further prolonged the patients’ survival.

Trial registration

Retrospectively registered: 33886

Increased Frequency of KRAS Mutations in African Americans Compared with Caucasians in Sporadic Colorectal Cancer

Objectives:

The basis for over-representation of colorectal cancer (CRC) in African-American (AA) populations compared with Caucasians are multifactorial and complex. Understanding the mechanisms for this racial disparity is critical for delivery of better care. Several studies have investigated sporadic CRC for differences in somatic mutations between AAs and Caucasians, but owing to small study sizes and conflicting results to date, no definitive conclusions have been reached.

Methods:

Here, we present the first systematic literature review and meta-analysis investigating the mutational differences in sporadic CRC between AAs and Caucasians focused on frequent driver mutations (APC,TP53, KRAS,PI3CA, FBXW7,SMAD4, and BRAF). Publication inclusion criteria comprised sporadic CRC, human subjects, English language, information on ethnicity (AA, Caucasian, or both), total subject number >20, and information on mutation frequencies.

Results:

We identified 6,234 publications. Meta-analysis for APC, TP54, FBXW7, or SMAD4 was not possible owing to paucity of data. KRAS mutations were statistically less frequent in non-Hispanic Whites when compared with AAs (odds ratio, 0.640; 95% confidence interval (CI): 0.5342–0.7666; P=0.0001), while the mutational differences observed in BRAF and PI3CA did not reach statistical significance.

Conclusions:

Here, we report the mutational patterns for KRAS, BRAF, and PI3CA in sporadic CRC of AAs and Caucasians in a systematic meta-analysis of previously published data. We identified an increase in KRAS mutations in sporadic CRC in AAs, which may contribute to worse prognosis and increased mortality of CRC in AAs. Future studies investigating health-care disparities in CRC in AAs should control for KRAS mutational frequency.

Targeting BRAF in metastatic colorectal cancer: Maximizing molecular approaches

Oncogenic mutations in B-type Raf kinase (BRAF) occur in 7-10% of metastatic colorectal cancers (mCRC). Despite recent improvements in survival in the general population of patients with mCRC, patients with BRAF-mutant mCRC continue to have poor response to most systemic therapies, and prognosis remains poor. There is a substantial unmet need for novel therapeutic strategies to treat patients with BRAF-mutant mCRC. This review outlines the epidemiology, molecular pathogenesis, prognosis, and mechanisms of treatment resistance of BRAF-mutated CRC. Additionally, this review highlights novel therapeutic strategies aimed at enhancing response and improving outcomes.

The efficacy and safety of panitumumab plus irrinotecan-based chemotherapy in the treatment of metastatic colorectal cancer: A meta-analysis

BACKGROUND

Panitumumab, a fully human monoclonal antibody targeting epidermal growth factor receptor, is used in combination with chemotherapy for patients with metastatic colorectal cancer (mCRC). However, the effects of panitumumab in combination with irrinotecan-based chemotherapy remain uncertain. Therefore, we conducted this meta-analysis to assess the efficacy and safety of combination treatment of panitumumab plus chemotherapy in the treatment of mCRC.

METHODS

By searching electronic databases (PubMed, Embase, and Web of Science), all clinical trials which assessed the effects of panitumumab plus irrinotecan-based chemotherapy in mCRC would be included. Main outcome measures included progression-free survival (PFS), overall survival (OS), overall response rate (ORR), and adverse events. Pooled estimates were calculated by a fixed-effects model or random-effects model, according to the heterogeneity among the included studies.

RESULTS

Eleven trials with a total number of 1338 patients met the inclusion criteria and were included in this meta-analysis. The combination treatment of panitumumab and irrinotecan-based chemotherapy was associated with a median PFS of 5.83 months, OS of 11.15 months, and ORR of 33%. Subgroup analysis showed that, in the first-line and second-line treatment, the combination therapy for PFS was 9.27 and 5.01 months, for OS was 8.87 and 11.68 months, and for ORR was 61% and 26%, respectively. In the wild-type and mutant KRAS populations, the combination therapy for PFS was 5.76 and 5.27 months, for OS was 11.15 and 10.64 months, and for ORR was 37% and 18%, respectively. Moreover, combination therapy also induced an incidence of 56% treatment-related adverse events.

CONCLUSION

Panitumumab plus irrinotecan-based chemotherapy is effective and well-tolerated in the treatment of patients with mCRC, especially in those with wild-type KRAS tumors.

Molecular spectrum of KRAS, NRAS, BRAF, PIK3CA, TP53, and APC somatic gene mutations in Arab patients with colorectal cancer: determination of frequency and distribution pattern

BACKGROUND

The frequency rates of mutations such as KRAS, NRAS, BRAF, and PIK3CA in colorectal cancer (CRC) differ among populations. The aim of this study was to assess mutation frequencies in the Arab population and determine their correlations with certain clinicopathological features.

METHODS

Arab patients from the Arab Gulf region and a population of age- and sex-matched Western patients with CRC whose tumors were evaluated with next-generation sequencing (NGS) were identified and retrospectively reviewed. The mutation rates of KRAS, NRAS, BRAF, PIK3CA, TP53, and APC were recorded, along with clinicopathological features. Other somatic mutation and their rates were also identified. Fisher's exact test was used to determine the association between mutation status and clinical features.

RESULTS

A total of 198 cases were identified; 99 Arab patients and 99 Western patients. Fifty-two point seven percent of Arab patients had stage IV disease at initial presentation, 74.2% had left-sided tumors. Eighty-nine point two percent had tubular adenocarcinoma and 10.8% had mucinous adenocarcinoma. The prevalence rates of KRAS, NRAS, BRAF, PIK3CA, TP53, APC, SMAD, FBXW7 mutations in Arab population were 44.4%, 4%, 4%, 13.1%, 52.5%, 27.3%, 2% and 3% respectively. Compared to 48.4%, 4%, 4%, 12.1%, 47.5%, 24.2%, 11.1% and 0% respectively in matched Western population. Associations between these mutations and patient clinicopathological features were not statistically significant.

CONCLUSIONS

This is the first study to report comprehensive hotspot mutations using NGS in Arab patients with CRC. The frequency of KRAS, NRAS, BRAF, TP53, APC and PIK3CA mutations were similar to reported frequencies in Western population except SMAD4 that had a lower frequency and higher frequency of FBXW7 mutation.

Tumor Take Rate Optimization for Colorectal Carcinoma Patient-Derived Xenograft Models

Background. For development of individualized treatment on a routine basis, transfer of patients' tumor tissue in a xenograft model (i.e., generation of patient-derived xenografts (PDX)) is desirable for molecular, biochemical, or functional analyses. Drawbacks are dissatisfactory tumor take rates, the necessity of fast tumor tissue processing, and extensive logistics demanding teamwork of surgeons, pathologists, and laboratory researchers. Methods. The take rates of ten colorectal cancer (CRC) tissue samples in immunodeficient mice were compared after direct cryopreservation and after a 24 h cooling period at 4°C prior to cryopreservation. Additionally, the effect of simultaneous Matrigel application on the take rates was investigated. Beside take rates, tumor growth characteristics and cell culture success were analyzed. Results. Tumor takes of CRC tissue samples were significantly improved after Matrigel application (8 versus 15 takes, p = 0.04). As expected, they diminished furthermore after 24 h cooling. Application of Matrigel could counteract this decrease significantly (2 versus 7 takes, p = 0.03). Cumulative take rate after cryopreservation was satisfactory (70%). Conclusion. Matrigel application after 24 h delay in tissue processing facilitates CRC PDX model development. These data help developing strategies for individualized tumor therapies in the context of multicenter clinical studies and for basic research on primary patient tumors.

MicroRNA expression profiling identifies miR-31-5p/3p as associated with time to progression in wild-type RAS metastatic colorectal cancer treated with cetuximab

The aim of our study was to investigate whether microRNAs (miRNAs) could serve as predictive biomarkers to anti-EGFR therapy (cetuximab, panitumumab) in patients with RAS wild-type (wt-RAS) metastatic colorectal cancer (mCRC). Historical cohort of 93 patients with mCRC (2006–2009) was included and further divided into exploratory and validation cohorts. MiRNAs expression profiling was performed on the exploratory cohort of 41 wt-KRAS mCRC patients treated with cetuximab to identify miRNAs associated with time to progression (TTP). The validation was performed on two independent cohorts: 28 patients of wt-RAS mCRC treated with cetuximab and 24 patients of wt-RAS mCRC treated with panitumumab. We identified 9 miRNAs with significantly different expression between responders and non-responders to cetuximab therapy (P ≤ 0.01). These 9 miRNAs were further evaluated in two independent cohorts of patients and miR-31-3p (P < 0.001) and miR-31-5p (P < 0.001) were successfully confirmed as strongly associated with TTP in wt-RAS mCRC patients treated with cetuximab but not panitumumab. When evaluated on the complete cohort of cetuximab patients (N = 69), miR-31-3p (HR, 5.10; 95% CI, 2.52–10.32; P < 0.001) and miR-31-5p (HR, 4.80; 95% CI, 2.50–9.24; P < 0.001) were correlated with TTP on the comparable level of significance. There was no difference in miR-31-5p/3p expression levels in RAS mutated and wild-type tumor samples. MiR-31-5p/3p are promising predictive biomarkers of cetuximab response in wt-RAS mCRC patients.

Colorectal cancer-related mutant KRAS alleles function as positive regulators of autophagy

The recent interest to modulate autophagy in cancer therapy has been hampered by the dual roles of this conserved catabolic process in cancer, highlighting the need for tailored approaches. Since RAS isoforms have been implicated in autophagy regulation and mutation of the KRAS oncogene is highly frequent in colorectal cancer (CRC), we questioned whether/how mutant KRAS alleles regulate autophagy in CRC and its implications. We established two original models, KRAS-humanized yeast and KRAS-non-cancer colon cells and showed that expression of mutated KRAS up-regulates starvation-induced autophagy in both. Accordingly, KRAS down-regulation inhibited autophagy in CRC-derived cells harboring KRAS mutations. We further show that KRAS-induced autophagy proceeds via up-regulation of the MEK/ERK pathway in both colon models and that KRAS and autophagy contribute to CRC cell survival during starvation. Since KRAS inhibitors have proven difficult to develop, our results suggest using autophagy inhibitors as a combined/alternative therapeutic approach in CRCs with mutant KRAS.

Second-line panitumumab as a triweekly dose for patients with wild-type KRAS exon 2 metastatic colorectal cancer: a single-institution experience

OBJECTIVE

Panitumumab administered as monotherapy in colorectal cancer (CRC) has shown response and disease stabilization rates of approximately 30%. The current study aimed to evaluate the progression-free survival (PFS) and overall survival (OS) of patients with metastatic colorectal cancer (mCRC) treated with panitumumab every 3 weeks as a second line treatment.

METHODS

This study is a retrospective analysis of 18 patients, aged more than 18 years, with wild-type KRAS exon 2 mCRC treated with panitumumab as a second-line single agent after progression on first-line chemotherapy.

RESULTS

The median number of courses received was 10 (range, 4-29), and the median duration of treatment was 30 weeks (range, 12-96 weeks). After a median follow-up period of 13 months, the median PFS was 6 months (range, 4.3-7.7 months) and the median OS was 11 months (range, 7.4-14.5 months). The median PFS was 4 months for patients with < grade 2 skin toxicity and 6 months (range, 4.5-7.5 months) for patients with ≥grade 2 skin rash (P=0.05). The median OS was 9 months (range, 6.4-11.5 months) and 14 months (range, 11.6-16.3 months) for the two groups of patients (P=0.002).

CONCLUSIONS

Panitumumab given every 3 weeks is effective and well tolerated in patients with advanced CRC that progressed after standard chemotherapy.

A Phase II Efficacy and Safety, Open-Label, Multicenter Study of Imprime PGG Injection in Combination With Cetuximab in Patients With Stage IV KRAS-Mutant Colorectal Cancer

BACKGROUND

Imprime PGG (β(1,6)-[poly-(1,3)-D-glucopyranosyl]-poly-β(1,3)-D-glucopyranose) is an innate immune cell modulator that primes neutrophils and monocytes/macrophages to exert antitumor activity against complement opsonized tumor cells. In patients with KRAS-mutant colorectal cancer (CRC), cetuximab alone is ineffective; however, it can bind to tumor cells and induce opsonization for recognition by Imprime PGG-bound innate immune cells. The primary objective of this study was to determine the antitumor activity of Imprime PGG in combination with cetuximab in patients with KRAS-mutant metastatic CRC.

PATIENTS AND METHODS

The study had a 2-stage Simon optimal design with 80% power to detect a target objective response rate (ORR) of ≥10% at a 10% significance level. Patients received weekly Imprime PGG (4 mg/kg) and cetuximab (loading dose, 400 mg/m(2), then 250 mg/m(2)) intravenously. The primary end point was ORR; secondary end points included duration of response (DOR), time to progression (TTP), overall survival (OS), disease control rate, progression-free survival, and safety. Stage 1 of the study was to enroll 17 evaluable patients.

RESULTS

One partial response (5.6%) was observed among 18 patients enrolled into stage 1. Median DOR was 4.2 months, TTP 2.7 months, and OS 6.6 months. Overall, observed toxicity was as expected from cetuximab alone. The most common (≥20%) adverse events related to Imprime PGG were fatigue (7 patients; 38.9%), infusion reaction (4 patients; 22.2%), and headache (4 patients; 22.2%). There was no Grade 4 toxicity nor treatment-related deaths.

CONCLUSION

Imprime PGG in combination with cetuximab treatment in patients with KRAS-mutant CRC showed compelling, albeit modest, clinical activity. This study provides proof of principle that Imprime PGG, in combination with complement-activating antibodies, is associated with clinical activity.

Panitumumab Use in Metastatic Colorectal Cancer and Patterns of KRAS Testing: Results from a Europe-Wide Physician Survey and Medical Records Review

Background

From 2008–2013, the European indication for panitumumab required that patients’ tumor KRAS exon 2 mutation status was known prior to starting treatment. To evaluate physician awareness of panitumumab prescribing information and how physicians prescribe panitumumab in patients with metastatic colorectal cancer (mCRC), two European multi-country, cross-sectional, observational studies were initiated in 2012: a physician survey and a medical records review. The first two out of three planned rounds for each study are reported.

Methods

The primary objective in the physician survey was to estimate the prevalence of KRAS testing, and in the medical records review, it was to evaluate the effect of test results on patterns of panitumumab use. The medical records review study also included a pathologists’ survey.

Results

In the physician survey, nearly all oncologists (299/301) were aware of the correct panitumumab indication and the need to test patients’ tumor KRAS status before treatment with panitumumab. Nearly all oncologists (283/301) had in the past 6 months of clinical practice administered panitumumab correctly to mCRC patients with wild-type KRAS status. In the medical records review, 97.5% of participating oncologists (77/79) conducted a KRAS test for all of their patients prior to prescribing panitumumab. Four patients (1.3%) did not have tumor KRAS mutation status tested prior to starting panitumumab treatment. Approximately one-quarter of patients (85/306) were treated with panitumumab and concurrent oxaliplatin-containing chemotherapy; of these, 83/85 had confirmed wild-type KRAS status prior to starting panitumumab treatment. All 56 referred laboratories that participated used a Conformité Européenne-marked or otherwise validated KRAS detection method, and nearly all (55/56) participated in a quality assurance scheme.

Conclusions

There was a high level of knowledge amongst oncologists around panitumumab prescribing information and the need to test and confirm patients’ tumors as being wild-type KRAS prior to treatment with panitumumab, with or without concurrent oxaliplatin-containing therapy.

Anti-HER3 Monoclonal Antibody Inhibits Acquired Trastuzumab-Resistant Gynecologic Cancers

BACKGROUND

Antibody resistance, both de novo and acquired, is usually related to high risk of recurrence and lower survival rate in gynecologic cancers. Prevention or reversal of the resistance often yields beneficial clinical results. It was reported that anti-human epidermal growth factor receptor 3 monoclonal antibody was effective against trastuzumab-resistant breast cancer cells. Here in our laboratory, an acquired trastuzumab-resistant ovarian cancer cell line, SKOV3-T, was established previously. Further, human epidermal growth factor receptor 3 was observed to be upregulated in this cell line by microarray detection, suggesting that the antagonist against human epidermal growth factor receptor 3 might be effective to inhibit the resistant cells.

METHODS

We developed an anti-human epidermal growth factor receptor 3 monoclonal antibody, LMAb3, and its affinity to bind human epidermal growth factor receptor 3 was calculated by the Biacore method. Preliminarily, LMAb3's antitumor activity was evaluated in vitro using cell growth/proliferation and clone formation assays in the breast cancer cell line MCF-7. Furthermore, LMAb3 was also evaluated for its inhibitory effect on the carcinogenicity of the SKOV3-T cells, which were induced to overexpress human epidermal growth factor receptor 3, both in vitro and in vivo. The possible underlying signal transduction mechanisms were also identified by Western blot in the MCF-7 and SKOV3-T cells.

RESULTS

LMAb3 was able to inhibit the cell growth/proliferation, clone, and tumor formation both in vitro (in the MCF-7 and SKOV3-T cells) and in vivo. The underlying mechanism of LMAb3 possibly involves inactivation of the HER family proteins (human epidermal growth factor receptor 1, human epidermal growth factor receptor 2, and especially human epidermal growth factor receptor 3) as well as the downstream mitogen-activated protein kinase and protein kinase B pathways.

CONCLUSION

Our work suggests that satisfactory curative effects might be achieved with LMAb3 to treat the trastuzumab-resistant, human epidermal growth factor receptor 3-positive cases of gynecologic cancers.

Meta-analysis of BRAF mutation as a predictive biomarker of benefit from anti-EGFR monoclonal antibody therapy for RAS wild-type metastatic colorectal cancer

Background:

Metastatic colorectal cancer (mCRC) that harbours a BRAF V600E mutation (BRAF MT) is associated with poorer outcomes. However, whether this mutation is predictive of treatment benefit from anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs) is uncertain.

Methods:

We conducted a systematic review and meta-analysis of randomised controlled trials (RCTs) published up to July 2014 that evaluated the effect of BRAF MT on the treatment benefit from anti-EGFR mAbs for mCRC.

Results:

Seven RCTs met the inclusion criteria for assessment of overall survival (OS), whereas eight RCTs met the inclusion criteria for assessment of progression-free survival (PFS). For RAS WT/BRAF MT tumours, the hazard ratio for OS benefit with anti-EGFR mAbs was 0.97 (95% CI; 0.67–1.41), whereas the hazard ratio was 0.81 (95% CI; 0.70–0.95) for RAS WT/BRAF WT tumours. However, the test of interaction (P=0.43) was not statistically significant, highlighting that the observed differences in the effect of anti-EGFR mAbs on OS according to the BRAF mutation status may be due to chance alone. Regarding PFS benefit with anti-EGFR mAbs, the hazard ratio was 0.86 (95% CI; 0.61–1.21) for RAS WT/BRAF MT tumours as compared with 0.62 (95% CI; 0.50–0.77) for RAS WT/BRAF WT tumours (test of interaction, P=0.07).

Interpretation:

This meta-analysis demonstrates that there is insufficient evidence to definitively state that RAS WT/BRAF MT individuals attain a different treatment benefit from anti-EGFR mAbs for mCRC compared with RAS WT/BRAF WT individuals. As such, there are insufficient data to justify the exclusion of anti-EGFR mAb therapy for patients with RAS WT/BRAF MT mCRC.

Panitumumab in Metastatic Colorectal Cancer: The Importance of Tumour RAS Status

Tumour biomarker status is being used more and more frequently to guide treatment decisions in patients with metastatic colorectal cancer (mCRC). Continued cycles of hypothesis generation and biomarker testing in retrospective, prospective-retrospective and prospective analyses from studies of the epidermal growth factor (EGFR)-targeted monoclonal antibodies (mAbs), panitumumab and cetuximab, have resulted in improved patient selection in mCRC. Initial data suggested EGFR-targeted mAb treatment should be limited to patients with KRAS exon 2 wild-type (WT) tumours, but the availability of tumour samples from large phase III studies permitted evaluation of additional potential biomarkers of activity for these agents. Subsequent analyses further refined the target population to those patients whose tumours were WT for KRAS and NRAS exons 2, 3 and 4 (i.e., those with RAS WT status). Here, we review key clinical data for panitumumab in mCRC across the lines of treatment, assessing in detail the impact of more comprehensive RAS selection on patient outcomes. Panitumumab data across first- to third-line therapy consistently demonstrate that by testing tumour RAS status, it is possible to select patients more likely to benefit from treatment.

Establishment and characterization of cell lines from chromosomal instable colorectal cancer

AIM: To generate novel tumor models for preclinical validation of biomarkers that allow drug response prediction and individual therapeutic decisions.

METHODS: Cell line establishment was conducted by both direct in vitro culturing and in vivo xenografting followed by in vitro culturing procedure. A comprehensive characterization was subsequently performed. This included quality control, consisting of the confirmation of human and colorectal cancer (CRC) origin by DNA fingerprint and epithelial cell adhesion molecule (EpCAM) staining, as well as mycoplasma and human virus testing. Phenotypic analysis was done by light microscopy and multicolor flow cytometry. Histopathological examination (β-catenin and cytokeratin staining) was conducted in direct comparison to parental tumor tissues. Extensive molecular-pathological profiling included mutation analysis for CRC-associated driver mutations, assessment of chromosomal and microsatellite instability, and the grade of CpG island methylation. Additionally, an array-based comparative genomic hybridization analysis was performed. Drug responsiveness was assessed for a panel of classical and novel substances in clinical use for the treatment of solid cancers. Finally, tumorigenicity of the cell lines was tested by xenografting into immunocompromised nude mice.

RESULTS: Herein we describe the establishment of three ultra-low passage cell lines from two individual patients suffering from sporadic CRC. One cell line was derived directly from an early stage case (HROC18), whereas two cell lines could be established both direct from patient material and after xenografting from a late stage tumor (HROC32). All cell lines were free of contaminating mycoplasma and viruses. Molecular-pathological analysis allowed all cell lines to be classified as chromosomal instable (CIN⁺). They were aneuploid, with CpG island promoter methylation and microsatellite instability being absent. The following mutational profile was observed both in the cell lines and the parental tumor tissue: HROC18: APC^mut, p53^mut, K-ras^wt; HROC32: APC^wt, p53^mut, K-ras^mut. All cell lines were characterized as epithelial (EpCAM⁺) cells, showing distinct morphology and migration speed, but comparable growth kinetics. The cell lines showed different patterns of response towards clinically approved and novel drugs, with HROC18 being more resistant than HROC32 cells. Finally, in vivo tumorigenicity was demonstrated.

CONCLUSION: We successfully established and characterized novel ultra-low passage patient-derived CRC models as useful instruments for analyzing biological characteristics associated with the CIN⁺ phenotype.

KRAS mutation testing in clinical practice

Activating mutation of KRAS plays a significant role in the pathogenesis of common human malignancies and molecular testing of KRAS mutation has emerged as an essential biomarker in the current practice of clinical oncology. The presence of KRAS mutation is generally associated with clinical aggressiveness of the cancer and reduced survival of the patient. Therapeutically, KRAS mutation testing has maximum utility in stratifying metastatic colorectal carcinoma and lung cancer patients for treatment with targeted therapy. Diagnostically, KRAS mutation testing is useful in the workup of pancreaticobiliary and thyroid cancers, particularly using cytological specimens. In the era of precision medicine, the role of KRAS mutation testing is poised to expand, likely in a setting of combinatorial therapeutic strategy and requiring additional mutation testing of its upstream and/or downstream effectors.

Anti-IGF-1R monoclonal antibody inhibits the carcinogenicity activity of acquired trastuzumab-resistant SKOV3

Background

Antibody resistance, not only de novo but also acquired cases, usually exists and is related with lower survival rate and high risk of recurrence. Reversing the resistance often results in better clinical therapeutic effect. Previously, we established a trastuzumab-resistant ovarian cancer cell line, named as SKOV3-T, with lower HER2 and induced higher IGF-1R expression level to keep cell survival.

Methods

IGF-1R was identified important for SKOV3-T growth. Then, a novel anti-IGF-1R monoclonal antibody, named as LMAb1, was used to inhibit SKOV3-T in cell growth/proliferation, migration, clone formation and in vivo carcinogenicity.

Results

In both in vitro and in vivo assays, LMAb1 showed effective anti-tumor function, especially when being used in combination with trastuzumab, which was beneficial to longer survival time of mice as well as smaller tumor. It was also confirmed preliminarily that the mechanism of antibody might be to inhibit the activation of IGF-1R and downstream MAPK, AKT pathway transduction.

Conclusion

We achieved satisfactory anti-tumor activity using trastuzumab plus LMAb1 in trastuzumab-resistant ovarian cancer model. In similar cases, not only acquired but also de novo, good curative effect might be achieved using combined antibody therapy strategies.

Low incidence of IL6ST (gp130) mutations in exon 6 in lung cancer of a Chinese cohort

Lung cancer is an inflammation-associated epithelial carcinoma. A highly active interleukin 6 (IL-6)/glycoprotein 130 (gp130)/signal transducer and activator of transcription 3 (STAT3) pathway has been identified in a subset of primary lung cancer and closely correlated with tumor progression and poor prognosis. In a previous study, the frequent occurrence of somatic gain-of-function mutations was observed in the gp130-encoding IL6ST gene in exon 6 in 60% of inflammatory hepatocellular adenomas. Prompted by this finding, we assessed 110 Chinese lung carcinomas using PCR and direct DNA sequencing but found no somatic mutation of IL6ST in exon 6. However, one new potential germline missense mutation c.599C>G was identified in one adenocarcinoma that harbors wild-type epidermal growth factor receptor and KRAS. Protein modeling analysis showed that this mutation might not affect the gp130 protein conformation. Moreover, activated STAT3 was observed in most of the lung tumor tissues at a higher level than that in matched normal lung tissues. In conclusion, the c.599C>G mutation may be a new single nucleotide polymorphism of IL6ST, but mutations in exon 6 of this gene are not apparently common genetic variations occurring and leading to constitutive activation of STAT3 in lung cancer.

Molecular spectrum of KRAS, BRAF, and PIK3CA gene mutation: determination of frequency, distribution pattern in Indian colorectal carcinoma

Molecular evaluation of KRAS, BRAF, and PIK3CA mutation has become an important part in colorectal carcinoma evaluation, and their alterations may determine the therapeutic response to anti-EGFR therapy. The current study demonstrates the evaluation of KRAS, BRAF, and PIK3CA mutation using direct sequencing in 204 samples. The frequency of KRAS, BRAF, and PIK3CA mutations was 23.5, 9.8, and 5.9 %, respectively. Five different substitution mutations at KRAS codon 12 (G12S, G12D, G12A, G12V, and G12C) and one substitution type at codon 13 (G13D) were observed. KRAS mutations were significantly higher in patients who were >50 years, and were associated with moderate/poorly differentiated tumors and adenocarcinomas. All mutations in BRAF gene were of V600E type, which were frequent in patients who were ≤ 50 years. Unlike KRAS mutations, BRAF mutations were more frequent in well-differentiated tumors and right-sided tumors. PIK3CA-E545K was the most recurrent mutation while other mutations detected were T544I, Q546R, H1047R, G1049S, and D1056N. No significant association of PIK3CA mutation with age, tumor differentiation, location, and other parameters was noted. No concomitant mutation of KRAS and BRAF mutations was observed, while, interestingly, five cases showed concurrent mutation of KRAS and PIK3CA mutations. In conclusion, to our knowledge, this is the first study to evaluate the PIK3CA mutation in Indian CRC patients. The frequency of KRAS, BRAF, and PIK3CA was similar to worldwide reports. Furthermore, identification of molecular markers has unique strengths, and can provide insights into the pathogenic process and help optimize personalized prevention and therapy.

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.

Anti-epidermal growth factor receptor monoclonal antibody-based therapy for metastatic colorectal cancer: a meta-analysis of the effect of PIK3CA mutations in KRAS wild-type patients

INTRODUCTION

We conducted a meta-analysis to dissect the association between PIK3CA mutations (exon 9 and exon 20) and resistance to anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (MoAbs) in KRAS wild-type metastatic colorectal cancer (mCRC) patients.

MATERIAL AND METHODS

In 11 previously published studies, 864 cancer patients were treated with cetuximab or panitumumab-based therapy. Primary outcomes included objective response (complete response + partial response vs. stable disease + progressive disease), progression-free survival (PFS), and overall survival (OS). We calculated the odds ratio (OR) or hazard ratio (HR) with 95% confidence intervals (CIs) to estimate the risk or hazard. We found consistent and clinically substantial risk or hazard for objective response, PFS, and OS in the cetuximab or panitumumab-treated mCRC patients.

RESULTS

PIK3CA mutations as a whole were associated with reduced response and poor PFS and OS in KRAS wild-type mCRC patients (objective response: OR = 0.42 and 95% CI 0.23-0.75; PFS: HR = 1.54 and 95% CI 1.13-2.09; and OS: HR = 1.4 and 95% CI 1.02-1.91). PIK3CA exon 9 mutations had no effect, whereas exon 20 mutations were associated with a worse outcome compared with wild types, with an OR of 0.21 (95% CI 0.05-0.93).

CONCLUSIONS

PIK3CA mutations as a whole might be useful prognostic factors for assessing clinical outcomes of anti-EGFR MoAb-based chemotherapies in KRAS wild-type mCRC patients. In particular, PIK3CA exon 20 mutations were significantly associated with lack of response.

K-RAS mutation profile in Puerto Rican patients with colorectal cancer: trends from April 2009 to January 2011

The frequency of K-RAS mutations ranges between 30% and 48% among the Caucasian, Asian, and European populations and these mutations are predictors of response to EGFR therapies. We sought to determine the expression of K-RAS gene mutations among colorectal cancer patients in PuertoRico. A retrospective study was conducted to determine the expression of mutant K-RAS among colorectal cancer patients in Puerto Rico between April 2009 and January 2011. The mutant expression of K-RAS was found in 39% (n=195) of the Puerto Rican population, and was more common in the age group of 51-69 years (53.8%) and in males (55.4%, p&gt;0.05). Moreover, mutant K-RAS was more commonly found in tumors of the proximal area (43.8%; p=0.03), with distant metastasis (43.3%, p=0.018), with a mucinous histotype (31.7% p&gt;0.05), and in ulcerated tumors (38.8%, p&gt;0.05). K-RAS mutations were observed on codon 12 (87.7%) and codon 13 (12.3%). The most frequent mutation on codon 12 was 12 ASP (39.5%), followed by 12 VAL (25.4%) that is associated with a significant decrease in overall cancer survival. The mutant expression of K-RAS in cases of rectum carcinoma was 39.5%, where the most common mutation was 12 VAL (37.5%). The frequency of K-RAS mutations in the Puerto Rican population here studied was 39% and mutant K-RAS was associated with advanced colorectal cancer stage, mucinous histotype, and ulcerated tumors.

Open-label, multicentre expansion cohort to evaluate imgatuzumab in pre-treated patients with KRAS-mutant advanced colorectal carcinoma

AIM

Imgatuzumab (GA201) is a novel anti-epidermal growth factor receptor (anti-EGFR) antibody glycoengineered for enhanced antibody-dependent cell-mediated cytotoxicity (ADCC). We investigated the efficacy of imgatuzumab in patients with EGFR-positive, KRAS-mutant advanced colorectal cancer.

METHODS

Patients received single-agent imgatuzumab (1400mg on day 1 and 8 followed by q2W) as third line therapy in an open-label, multicentre, non-randomised, expansion study. The primary end-point was tumour response. Pre- and on-treatment biopsies and blood samples were investigated for biomarkers related to imgatuzumab's believed mechanism of action (MoA).

RESULTS

25 patients were treated and the best overall response was stable disease occurring in 40% of patients at 8weeks, 24% at 16weeks and 8% (two patients) at 32weeks. Median overall survival was 9.3months (95% confidence interval (CI): 5.1-12.3). Treatment-related rash, hypomagnesaemia and infusion-related reactions were the most common adverse events. Comparison of pre- and post-treatment biopsies revealed that the number of tumour-infiltrating immune cells increased notably after one cycle of therapy (median compound immune reactive score of 1491 versus 898 cells/mm(3) at baseline), whereas the number of peripheral natural killer cells decreased. A potential association between baseline tumour immune infiltration and clinical efficacy was seen.

CONCLUSIONS

These data may suggest that the MoA of imgatuzumab involves ADCC-related immune effects in the tumour and is not limited to simple receptor blockade.

Gene expression profiles can predict panitumumab monotherapy responsiveness in human tumor xenograft models

BACKGROUND

Epidermal growth factor receptor (EGFR)-targeted agents have demonstrated clinical benefit in patients with cancer. Identifying tissue-of-origin-independent predictive biomarkers is important to optimally treat patients. We sought to identify a gene array profile that could predict responsiveness to panitumumab, a fully human EGFR-binding antibody, using preclinical models of human cancer.

METHODS

Mice bearing 25 different xenograft models were treated twice weekly with panitumumab or immunoglobulin G2 control to determine their responsiveness to panitumumab. Samples from these xenografts and untreated xenografts were arrayed on the Affymetrix human U133A gene chip to identify gene sets predicting responsiveness to panitumumab using univariate and multivariate analyses. The predictive models were validated using the leave-one-group-out (LOO) method.

RESULTS

Of the 25 xenograft models tested, 12 were responsive and 13 were resistant to panitumumab. Unsupervised analysis demonstrated that the xenograft models clustered by tissue type rather than responsiveness to panitumumab. After normalizing for tissue effects, samples clustered by responsiveness using an unsupervised multidimensional scaling. A multivariate selection algorithm was used to select 13 genes that could stratify xenograft models based on responsiveness after adjustment for tissue effects. The method was validated using the LOO method on a training set of 22 models and confirmed independently on three new models. In contrast, a univariate gene selection method resulted in higher misclassification rates.

CONCLUSION

A model was constructed from microarray data that prospectively predict responsiveness to panitumumab in xenograft models. This approach may help identify patients, independent of disease origin, likely to benefit from panitumumab.

Predictive and prognostic roles of BRAF mutation in patients with metastatic colorectal cancer treated with anti-epidermal growth factor receptor monoclonal antibodies: a meta-analysis

OBJECTIVE

This study aimed to evaluate the predictive and prognostic roles of BRAF mutation in patients with metastatic colorectal cancer (mCRC) treated with anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (MoAbs).

METHODS

Computer searches of the literature on BRAF mutation in mCRC patients were performed. Studies with objective response rate (ORR) to anti-EGFR MoAbs and/or overall survival (OS) and progression-free survival (PFS) with different BRAF gene expression in mCRC patients were eligible.

RESULTS

A total of 19 studies including 2875 patients was enrolled in the meta-analysis. BRAF mutation was detected in 246 patients. The ORR was 18.4% (40/217) in mutant BRAF group and 41.7% (831/1993) in the wild-type BRAF group. The overall risk ratio (RR) for the ORR of BRAF mutation patients compared with wild-type BRAF patients was 0.58 (95% confidence intervals [CI] 0.35-0.94, P = 0.027). The median PFS of patients with BRAF mutation was significantly shorter than that of patients with wild-type BRAF (hazard ratio [HR] 2.98, 95% CI 2.07-4.27, P < 0.001) and the median OS of patients with BRAF mutation was also significantly shorter than that of those with wild-type BRAF (HR 2.85, 95% CI 2.31-3.52, P < 0.001).

CONCLUSION

BRAF mutation is associated with poor response to anti-EGFR MoAbs and it is an adverse prognostic biomarker of the survival of patients with mCRC.

Pharmacokinetics of Irinotecan With and Without Panitumumab Coadministration in Patients With Metastatic Colorectal Cancer

This study examined the effects of panitumumab, a human monoclonal antibody against epidermal growth factor receptor (EGFR), on irinotecan pharmacokinetics. This phase I, open-label, multicenter, single-arm study enrolled patients with metastatic colorectal cancer (mCRC) without prior exposure to an EGFR inhibitor. In cycle 1, patients received irinotecan (180 mg/m(2) intravenously [IV]) on day 1 and panitumumab (6 mg/kg IV) on Day 4. In cycle 2 (2 weeks after cycle 1 panitumumab administration) and subsequent every-2-week cycles, patients received panitumumab followed immediately by irinotecan until disease progression or intolerability. Primary and secondary endpoints included Cmax and AUC of irinotecan after irinotecan infusion in cycles 1 and 2, and adverse events, respectively. Nineteen of 27 treated patients were eligible for pharmacokinetic analysis. Pharmacokinetic profiles of irinotecan with or without panitumumab coadministration were nearly identical. The 90% confidence intervals for ratios of geometric means for irinotecan Cmax and AUC with or without panitumumab were within the 80-125% interval, indicating that panitumumab had no apparent effects on irinotecan pharmacokinetics. Adverse events were as expected for irinotecan plus panitumumab combination therapy.

Methylation levels of LINE-1 in primary lesion and matched metastatic lesions of colorectal cancer

Background:

LINE-1 methylation level is a surrogate marker of global DNA methylation. LINE-1 methylation in primary colorectal cancers (CRCs) is highly variable and strongly associated with a poor prognosis. However, no study has examined LINE-1 methylation levels of metastatic CRCs in relation to prognosis or assessed the heterogeneity of LINE-1 methylation level within the primary CRCs.

Methods:

Pyrosequencing was used to quantify LINE-1 methylation level in 42 liver metastases, 26 matched primary tumours, and 6 matched lymph node (LN) metastases. KRAS, BRAF, and PIK3CA mutation status and microsatellite instability (MSI) status were also examined.

Results:

The distribution of LINE-1 methylation level in liver metastases was as follows: mean, 67.3; range, 37.1–90.1. Primary tumours showed LINE-1 methylation levels similar to those of matched liver and LN metastases. The difference in LINE-1 methylation level between superficial areas and invasive front areas was within 7.0 in all six cases evaluated. Prognostic impact of LINE-1 hypomethylation in liver metastases on overall survival was not observed. The concordance rate was 94% for KRAS, 100% for BRAF, 88% for PIK3CA, and 97% for MSI.

Conclusion:

Alteration of LINE-1 methylation level may occur in early CRC tumorigenesis, and the LINE-1 methylation level is relatively stable during CRC progression.

The prognostic role of BRAF mutation in metastatic colorectal cancer receiving anti-EGFR monoclonal antibodies: a meta-analysis

Background

BRAF mutation has been investigated as a prognostic factor in metastatic colorectal cancer (mCRC) undergoing anti-EGFR monoclonal antibodies (moAbs), but current results are still inconclusive. The aim of this meta-analysis was to evaluate the relationship between BRAF mutation status and the prognosis of mCRC patients treated with moAbs.

Methods

Eligible studies were identified by systematically searching Pubmed, the Cochrane Library, Web of Knowledge, and OVID. Risk ratio (RR) for overall response rate (ORR), Hazard ratios (HRs) for Progression free survival (PFS) and Overall survival (OS) were extracted or calculated. Prespecified subgroup analyses were conducted in KRAS wild-type and in different study types. The source of between-trial variation was explored by sensitivity analyses. Quality assessment was conducted by the Hayden’s criteria.

Results

A total of twenty one trials including 5229 patients were identified for the meta-analysis. 343 patients displayed BRAF mutations of 4616 (7.4%) patients with known BRAF status. Patients with BRAF wild-type (WT) showed decreased risks of progression and death with an improved PFS(HR 0.38, 95% confidence intervals 0.29–0.51) and an improved OS (HR 0.35 [0.29–0.42]), compared to BRAF mutant. In KRAS WT population, there were even larger PFS benefit (HR 0.29[0.19,0.43]) and larger OS benefit (HR 0.26 [0.20,0.35]) in BRAF WT. A response benefit for BRAF WT was observed (RR 0.31[0.18,0.53]) in KRAS WT patients, but not observed in unselected patients (RR 0.76 [0.43–1.33]). The results were consistent in the subgroup analysis of different study types. Heterogeneity between trials decreased in the subgroup and explained by sensitivity analysis. No publication bias of ORR, PFS and OS were detected.

Conclusions

The results indicate that BRAF mutant is a predictive biomarker for poor prognosis in mCRC patients undergoing anti-EGFR MoAbs therapy, especially in KRAS WT patients. Additional large prospective trials are required to confirm the predictive role of BRAF status.

A real-life experience using panitumumab in chemo-refractory metastatic colorectal cancer patients: a retrospective analysis at the Jewish General Hospital, 2009-2012

BACKGROUND

Panitumumab is a fully human monoclonal antibody, directed against the epidermal growth factor receptor, that was shown to be effective in third-line metastatic colorectal cancer. We performed a retrospective analysis of patients with chemo-refractory non-KRAS-mutated metastatic colorectal cancer, who received panitumumab at the Jewish General Hospital in Montreal, Canada, between 2009 and 2012.

METHODS

This chart review included 44 patients (median age: 60 years; performance status: 0-3), of whom 50% had already received three lines of treatment. The primary endpoint was progression-free survival (pfs). Secondary endpoints were overall survival and safety. Tumour progression was determined by radiologic assessments performed once every 3 months per clinical guidelines or by clinical deterioration as determined by the clinician-investigator.

RESULTS

In our sample, median pfs was 21.86 ± 5.23 weeks (95% confidence interval: 12.9 to 36.9 weeks) and overall survival was 35.14 ± 7.75 weeks (95% confidence interval: 25.6 to 73.4 weeks) with a median of 5 cycles of panitumumab treatment. The most frequently reported toxicities with panitumumab were skin toxicity (16.2% grade 3) and hypomagnesemia (10.8% grade 3). No infusion reactions were reported.

CONCLUSIONS

Despite a small sample size from a single institution, our survival and efficacy data are encouraging and comparable to results obtained from the registration panitumumab trial. Our findings suggest that panitumumab can be effective and tolerable in a real-world setting.

Novel drugs targeting the epidermal growth factor receptor and its downstream pathways in the treatment of colorectal cancer: a systematic review

Colorectal cancer is the second most common malignancy among men and women in the United States, and the 5-year survival rate remains poor despite recent advances in chemotherapy and targeted agents. The mainstay of therapy for advanced disease remains the cytotoxic chemotherapy including 5-FU, irinotecan, and oxaliplatin. The USFDA approval and introduction of targeted therapies, including cetuximab and panitumumab (monoclonal antibodies targeting the epidermal growth factor receptor (EGFR)) and bevacizumab (monoclonal antibody targeting the vascular epithelial growth factor (VEGF)), has improved the median survival of patients with metastatic colorectal cancer to around 24 months. Clearly, better and more efficacious drugs are needed, and target-specific agents remain the future of cancer treatment. On this front, rapid advances are being made, which are likely to change the future of the management of metastatic colorectal cancer. However, absence of specific biomarkers for the use of targeted agents, in the subset of population who will benefit from the treatment, remains a major drawback. In this paper, we review agents that are in phases 1 and 2 clinical development, specifically targeting the EGFR and its subsequent downstream pathways.

KRAS mutation testing in metastatic colorectal cancer

The KRAS oncogene is mutated in approximately 35%-45% of colorectal cancers, and KRAS mutational status testing has been highlighted in recent years. The most frequent mutations in this gene, point substitutions in codons 12 and 13, were validated as negative predictors of response to anti-epidermal growth factor receptor antibodies. Therefore, determining the KRAS mutational status of tumor samples has become an essential tool for managing patients with colorectal cancers. Currently, a variety of detection methods have been established to analyze the mutation status in the key regions of the KRAS gene; however, several challenges remain related to standardized and uniform testing, including the selection of tumor samples, tumor sample processing and optimal testing methods. Moreover, new testing strategies, in combination with the mutation analysis of BRAF, PIK3CA and loss of PTEN proposed by many researchers and pathologists, should be promoted. In addition, we recommend that microsatellite instability, a prognostic factor, be added to the abovementioned concomitant analysis. This review provides an overview of KRAS biology and the recent advances in KRAS mutation testing. This review also addresses other aspects of status testing for determining the appropriate treatment and offers insight into the potential drawbacks of mutational testing.

Panitumumab: a summary of clinical development in colorectal cancer and future directions

Panitumumab is a fully human, monoclonal antibody targeting the EGF receptor with proven clinical activity in KRAS wild-type metastatic colorectal carcinoma. Treatment with panitumumab has been shown to significantly improve response rate and progression-free survival in this subgroup of patients, with a manageable toxicity profile. Panitumumab's first worldwide indication was as a single agent in chemorefractory patients. Recently, the EMA approved its use as part of a chemotherapy regimen in first- and second-line settings, following the encouraging results of large randomized Phase III trials. In order to identify patients with higher chances of benefiting from the treatment, additional molecular aberrations in the EGF receptor signaling pathway are being investigated as predictive biomarkers. In this article we review 10 years of drug development, focusing on the clinical evidence for panitumumab's indication in metastatic colorectal cancer and future strategies of investigation.

Tumor penetration and epidermal growth factor receptor saturation by panitumumab correlate with antitumor activity in a preclinical model of human cancer

Background

Successful treatment of solid tumors relies on the ability of drugs to penetrate into the tumor tissue.

Methods

We examined the correlation of panitumumab (an anti-epidermal growth factor [EGFR] antibody) tumor penetration and EGFR saturation, a potential obstacle in large molecule drug delivery, using pharmacokinetics, pharmacodynamics, and tumor growth rate in an A431 epidermoid carcinoma xenograft model of human cancer. To determine receptor saturation, receptor occupancy, and levels of proliferation markers, immunohistochemical and flow cytometric methods were used. Pharmacokinetic data and modeling were used to calculate growth characteristics of panitumumab-treated tumors.

Results

Treatment with panitumumab in vivo inhibited pEGFR, Ki67 and pMAPK levels vs control. Tumor penetration and receptor saturation were dose- and time-dependent, reaching 100% and 78%, respectively. Significant tumor inhibition and eradication (p < 0.05) were observed; plasma concentration associated with tumor eradication was estimated to be 0.2 μg/ml. The tumor inhibition model was able to describe the mean tumor growth and death rates.

Conclusions

These data demonstrate that the antitumor activity of panitumumab correlates with its ability to penetrate into tumor tissue, occupy and inhibit activation of EGFR, and inhibit markers of proliferation and MAPK signaling.

KRAS mutation is present in a small subset of primary urinary bladder adenocarcinomas

AIMS

To determine whether KRAS mutations occur in primary bladder adenocarcinoma.

METHODS AND RESULTS

Twenty-six cases of primary urinary bladder adenocarcinoma were analysed. DNA was extracted from formalin-fixed, paraffin-embedded tissue and amplified with shifted termination assay technology, which recognizes wild-type or mutant target sequences and selectively extends detection primers with labelled nucleotides. A mutation in KRAS was found in three (11.5%) of 26 primary bladder adenocarcinomas. Two of these three cases exhibited a G13D mutation, whereas the remaining case contained a mutation in G12V. None of the ten cases of urothelial carcinoma with glandular differentiation displayed KRAS mutation. Colonic adenocarcinoma contained a KRAS mutation in 18 (33%) of 55 cases. There was no distinct difference with regard to grade, stage or outcome according to the limited clinicopathological data available. However, the two youngest patients, aged 32 and 39 years, in our study group, with a mean population age of 61 years, were found to have mutations in KRAS.

CONCLUSIONS

KRAS mutations are present in a small subset of primary urinary bladder adenocarcinomas. Future clinical trials for treatment of bladder adenocarcinoma, employing targeted therapies similar to those used for treatment of colon cancer, may also benefit from the predictive implications of KRAS mutational testing.

Comparative genomic analysis of primary versus metastatic colorectal carcinomas

PURPOSE

To compare the mutational and copy number profiles of primary and metastatic colorectal carcinomas (CRCs) using both unpaired and paired samples derived from primary and metastatic disease sites.

PATIENTS AND METHODS

We performed a multiplatform genomic analysis of 736 fresh frozen CRC tumors from 613 patients. The cohort included 84 patients in whom tumor tissue from both primary and metastatic sites was available and 31 patients with pairs of metastases. Tumors were analyzed for mutations in the KRAS, NRAS, BRAF, PIK3CA, and TP53 genes, with discordant results between paired samples further investigated by analyzing formalin-fixed, paraffin-embedded tissue and/or by 454 sequencing. Copy number aberrations in primary tumors and matched metastases were analyzed by comparative genomic hybridization (CGH).

RESULTS

TP53 mutations were more frequent in metastatic versus primary tumors (53.1% v 30.3%, respectively; P < .001), whereas BRAF mutations were significantly less frequent (1.9% v 7.7%, respectively; P = .01). The mutational status of the matched pairs was highly concordant (> 90% concordance for all five genes). Clonality analysis of array CGH data suggested that multiple CRC primary tumors or treatment-associated effects were likely etiologies for mutational and/or copy number profile differences between primary tumors and metastases.

CONCLUSION

For determining RAS, BRAF, and PIK3CA mutational status, genotyping of the primary CRC is sufficient for most patients. Biopsy of a metastatic site should be considered in patients with a history of multiple primary carcinomas and in the case of TP53 for patients who have undergone interval treatment with radiation or cytotoxic chemotherapies.

KRAS mutations in primary tumours and post-FOLFOX metastatic lesions in cases of colorectal cancer

BACKGROUND

KRAS mutations are predictive markers for the efficacy of anti-EGFR antibody therapies in patients with metastatic colorectal cancer. Although the mutational status of KRAS is reportedly highly concordant between primary and metastatic lesions, it is not yet clear whether genotoxic chemotherapies might induce additional mutations.

METHODS

A total of 63 lesions (23 baseline primary, 18 metastatic and 24 post-treatment metastatic) from 21 patients who were treated with FOLFOX as adjuvant therapy for stage III/IV colorectal cancer following curative resection were examined. The DNA samples were obtained from formalin-fixed paraffin-embedded specimens, and KRAS, NRAS, BRAF and PIK3CA mutations were evaluated.

RESULTS

The numbers of primary lesions with wild-type and mutant KRAS codons 12 and 13 were 8 and 13, respectively. The mutational status of KRAS remained concordant between the primary tumours and the post-FOLFOX metastatic lesions, irrespective of patient background, treatment duration and disease-free survival. Furthermore, the mutational statuses of the other genes evaluated were also concordant between the primary and metastatic lesions.

CONCLUSION

Because the mutational statuses of predictive biomarker genes were not altered by FOLFOX therapy, specimens from both primary tumours and post-FOLFOX tumour metastases might serve as valid sources of DNA for known genomic biomarker testing.

Prognostic value of different CT measurements in early therapy response evaluation in patients with metastatic colorectal cancer

Objectives: Patients with advanced stage colorectal carcinoma (CRC) display hepatic metastases on initial staging in up to 20% of cases. The effectiveness of chemotherapy is generally evaluated by computed tomography (CT) imaging using standardized criteria (RECIST). However, RECIST is not always optimal, and other criteria have been shown to correlate with pathologic response and overall survival. The aim of this study was to evaluate the prognostic value of different CT measurement for response assessment after initiation of chemotherapy in patients with synchronous colorectal cancer liver metastases. Methods: Fifty-five patients with CRC and synchronous hepatic metastases were evaluated retrospectively at 2 academic centers. Different size, volume, ratio and attenuation parameters were determined at baseline and after 3 cycles of chemotherapy. The prognostic value of baseline measurements and of the change between baseline and second measurements was analyzed using Kaplan–Meier estimates. Results: Median time to progression was 279 days, median overall survival was 704 days. In this selective patient population, neither a significant prognostic value of initial baseline CT parameters nor a prognostic value of the change between the first and the second CT measurements was found. Conclusion: Initial morphological response assessment using different CT measurements has no prognostic value concerning time to progression or overall survival in patients with synchronous colorectal liver metastases.

KRAS, BRAF and PIK3CA mutations and the loss of PTEN expression in Chinese patients with colorectal cancer

Background

To investigate the frequency and relationship of the KRAS, BRAF and PIK3CA mutations and the loss of PTEN expression in Chinese patients with colorectal cancer (CRC).

Methodology/Principal Findings

Genomic DNA was extracted from the formalin-fixed paraffin-embedded (FFPE) tissues of 69 patients with histologically confirmed CRC. Automated sequencing analysis was conducted to detect mutations in the KRAS (codons 12, 13, and 14), BRAF (codon 600) and PIK3CA (codons 542, 545 and 1047). PTEN protein expression was evaluated by immunohistochemistry on 3 mm FFPE tissue sections. Statistical analysis was carried out using SPSS 16.0 software. The frequency of KRAS, BRAF and PIK3CA mutations and loss of PTEN expression was 43.9% (25/57), 25.4% (15/59), 8.2% (5/61) and 47.8% (33/69), respectively. The most frequent mutation in KRAS, BRAF and PIK3CA was V14G (26.7% of all mutations), V600E (40.0% of all mutations) and V600L (40.0% of all mutations), and H1047L (80.0% of all mutations), respectivly. Six KRAS mutatant patients (24.0%) harbored BRAF mutations. BRAF and PIK3CA mutations were mutually exclusive. No significant correlation was observed between the four biomarkers and patients' characteristics.

Conclusions/Significance

BRAF mutation rate is much higher in this study than in other studies, and overlap a lot with KRAS mutations. Besides, the specific types of KRAS and PIK3CA mutations in Chinese patients could be quite different from that of patients in other countries. Further studies are warranted to examine their impact on prognosis and response to targeted treatment.

Three different KRAS statuses in three synchronous colorectal cancers

Treatments with monoclonal antibodies targeting the epidermal growth factor receptors (EGFR) have improved the prognosis of metastatic colorectal cancer (CRC). Mutated KRAS status is predictive of resistance to anti-EGFR agents and allows the selection of KRAS wild-type patients who may benefit from these targeted therapies. We report an original case of metastatic CRC including three synchronous primary tumors with three different KRAS statuses. We discuss the possible therapeutic impact of this clinical case and the role of multiple samplings for KRAS status determination.