Current opinion on optimal systemic treatment for metastatic colorectal cancer: outcome of the ACTG/AGITG expert meeting ECCO 2013

Personalized medicine: Stem cells in colorectal cancer treatment

Treatment failure in primary as well as metastatic cancer patients, caused by chemo and radioresistance, has reinforced the research for the applicability of personalized medicine. The use of stem cells (SCs) and cancer stem cells (CSCs) in such a treatment approach will be reviewed in this study. Colorectal cancer (CRC) SCs prove to be a promising asset for CRC treatment optimization both by serving as biomarkers for the current therapy modalities, by means of treatment personalization and patient/tumor stratification, as well as in the development of targeted therapies, selective for the stem cell population. Similar conclusions are drawn, regarding mesenchymal stromal cells (MSCs) and their effect in CRC therapy; while resident stromal cells (RSCs) of tumor microenvironment (TME) seem to promote the tumorigenic and metastatic processes in addition to conferring to the chemo- and radioresistance, under certain conditions they are able to improve the treatment outcome of CRC chemotherapy, e.g. by targeted enzyme/prodrug treatment of CRC cells. This review, points out the dynamic potential of CSCs and other SCs types in CRC treatment personalization as well as, in the improvement of current treatment approaches, opting to a higher therapeutic rate, improved prognosis, survival and quality of life for CRC patients.

Real-World Adherence in Patients with Metastatic Colorectal Cancer Treated with Trifluridine plus Tipiracil or Regorafenib

BACKGROUND

Trifluridine and tipiracil (FTD + TPI) and regorafenib (REG) are approved treatments for the treatment of refractory metastatic colorectal cancer (mCRC). This study assesses adherence and duration of therapy with FTD + TPI versus REG and explores the effect of sequencing on adherence.

MATERIALS AND METHODS

Adults diagnosed with mCRC were identified in the IQVIA Real-World Data Adjudicated Claims: U.S. database (October 2014-July 2017). The observation period spanned from the index date (first dispensing of FTD + TPI or REG) to the earliest of a switch to another mCRC agent, the end of continuous enrollment, or the end of data availability. Medication possession ratio (MPR), proportion of days covered (PDC), and persistence and time to discontinuation (gap ≥45 days) were compared between FTD + TPI and REG users and among switchers (FTD + TPI-to-REG vs. REG-to-FTD + TPI).

RESULTS

A total of 469 FTD + TPI and 311 REG users were identified. FTD + TPI users had higher compliance with an MPR ≥80% (odds ratio [OR], 2.47; p < .001) and PDC ≥80% (OR, 2.77; p < .001). FTD + TPI users had better persistence (82.8% vs. 68.0%; p < .001) and lower risk of discontinuation (hazard ratio [HR], 0.76; p = .006). Among switchers (96 FTD + TPI-to-REG; 83 REG-to-FTD + TPI), those switching from FTD + TPI to REG were more likely to have an MPR ≥80% (OR, 2.91; p < .001) and PDC ≥80% (OR, 4.60; p < .001) compared with REG-to-FTD + TPI switchers while treated with these drugs. Additionally, FTD + TPI-to-REG switchers had a lower risk of first treatment discontinuation (HR, 0.66; p = .009).

CONCLUSION

FTD + TPI users had significantly higher adherence and persistence, and patients who were treated with FTD + TPI before switching to REG also had higher adherence and persistence outcomes.

IMPLICATIONS FOR PRACTICE

Trifluridine plus tipiracil (FTD + TPI) and regorafenib (REG) prolong survival in refractory metastatic colorectal cancer (mCRC) but have different tolerability profiles. This study assessed real-world adherence to treatment with FTD + TPI versus REG and compared outcomes among patients who switched from FTD + TPI to REG and vice versa. FTD + TPI was associated with significantly higher medication adherence and longer time to discontinuation than REG. Patients treated with FTD + TPI prior to switching to REG also showed higher adherence outcomes. Findings could help inform decision making regarding the choice and sequencing of treatment with FTD + TPI versus REG in patients with mCRC.

Cost-effectiveness analysis of selective first-line use of biologics for unresectable RAS wild-type left-sided metastatic colorectal cancer

Background

Evidence from a retrospective analysis of multiple large phase iii trials suggested that primary tumour location (ptl) in RAS wild-type metastatic colorectal cancer (wtRAS mcrc) might have predictive value with respect to response to drug therapies. Recent studies also show a potential preferential benefit for epidermal growth factor inhibitors (egfris) for left-sided tumours. In the present study, we aimed to determine the incremental cost-effectiveness ratio (icer) for the first-line use of an egfri for patients with left-sided wtRAS mcrc.

Methods

We developed a state-transition model to determine the cost effectiveness of alternative treatment strategies in patients with left-sided mcrc:■ Standard of care■ Use of an egfri in first-line therapyThe cohort for the study consisted of patients diagnosed with unresectable wtRAS mcrc with an indication for chemotherapy and previously documented ptl. Model parameters were obtained from the published literature and calibration. The perspective was that of a provincial ministry of health in Canada. We used a 5-year time horizon and an annual discount rate of 1.5%.

Results

Selecting patients for first-line egfri treatment based on left-sided location of their colorectal primary tumour was more effective than the standard of care, resulting in an increase in quality-adjusted life-years (qalys) of 0.226 (or 0.644 life-years gained). However, the strategy was also more expensive, costing an average of $60,639 more per patient treated. The resulting icer was $268,094 per qaly. A 35% price reduction in the cost of egfri would be needed to make this strategy cost-effective at a willingness-to-pay threshold (wtp) of $100,000 per qaly.

Conclusions

Selective use of an egfri based on ptl was more cost-effective than unselected use of those agents; however, based on traditional wtp thresholds, it was still not cost-effective. While awaiting the elucidation of more precise predictive biomarkers that might improve cost-effectiveness, the price of egfris could be reduced to meet the wtp threshold.

Efficacy and safety of FOLFIRI and biotherapy versus FOLFIRI alone for metastatic colorectal cancer patients: A meta-analysis

BACKGROUND

Previous randomized controlled trials (RCTs) and meta-analyses have demonstrated the useless of FOLFIRI alone for previously treated patients with metastatic colorectal cancer (mCRC). The role of FOLFIRI regimen combined with biological therapy is unknown. The purpose of this meta-analysis is to evaluate the efficacy and safety of combining biological therapy with chemotherapy in previously treated patients with mCRC.

METHODS

MEDLINE, EMBASE, Web of Science, Cochrane library, and ClinicalTrials.gov were searched. Eligible studies were RCTs that evaluated the efficacy and safety of the FOLFIRI regimen with or without biological therapy for previously treated patients with mCRC. The hazard ratio (HR) or risk ratio (RR) with 95% confidence interval was estimated. The Chi-squared and I-squared tests were used to assess the statistical heterogeneity.

RESULTS

The literature search identified 7 RCTs that met the inclusion criteria for the meta-analysis, and 3680 patients with mCRC were included. The meta-analysis showed that combined therapy was associated with a significant improved progression-free survival (PFS) (HR = 0.78, 95% CI = 0.72-0.85, P < .001), overall survival (OS) (HR = 0.84, 95% CI = 0.77-0.92, P < .001), and overall response rate (ORR) (RR = 1.70, 95% CI = 1.25-2.31, P = .001). Sensitivity analysis suggested that combined therapy versus FOLFIRI alone might increase the risk of Grade 3/4 AEs.

CONCLUSION

The addition of biological therapy to the FOLFIRI regimen improved the PFS, OS, and ORR compared with FOLFIRI alone for previously treated patients with mCRC. Long-term survival outcomes are warranted.

Overcoming dynamic molecular heterogeneity in metastatic colorectal cancer: Multikinase inhibition with regorafenib and the case of rechallenge with anti-EGFR

In metastatic colorectal cancer (mCRC), fluorouracil-based combination therapy with oxaliplatin or irinotecan is the mainstay of first-line treatment. Patient survival has been significantly improved with the introduction of monoclonal antibodies against VEGF (bevacizumab), VEGFR2 (ramucirumab) or EGFR (cetuximab or panitumumab) in first- and second-line therapies. However, all patients treated with chemotherapy and targeted therapies will eventually relapse, and recently the emergence of alterations in EGFR, RAS, BRAF, ERB-B2, MET and possibly in other genes has been shown to jeopardize response to EGFR blockade. In chemorefractory patients, multikinase inhibition with regorafenib has proved to be effective and rechallenge with chemotherapy or anti-EGFR agents is empirically pursued. This review will critically discuss how the evolving knowledge of mechanisms of resistance driven by intratumoural dynamic molecular heterogeneity can impact on rational choice of treatments in this setting.

BRAF Mutation Testing and Metastatic Colorectal Cancer in the Community Setting: Is There an Urgent Need for More Education?

BACKGROUND

Patients with metastatic colorectal cancer (mCRC) with BRAF mutation (BRAF MT) generally have a poorer prognosis. BRAF MT may also have implications for treatment strategy. Despite this, inclusion of BRAF in routine molecular testing varies. Here we report the frequency of BRAF reporting in the South Australian (SA) mCRC registry reflecting community practice, together with the survival outcomes based on mutation status.

METHODS

The SA population-based mCRC registry was analysed to assess the number of patients where a BRAF MT result was available. The patient characteristics are reported and overall survival was analysed using the Kaplan-Meier method.

RESULTS

Of the 3639 patients who have been entered in the registry, only 6.2% (227) have BRAF MT results available. Of the patients tested, the BRAF MT rate is 12.7%. The mutation rate was highest in rightsided primary; right colon 23 versus left colon 8.9% and rectum 7%. There was no significant difference in median age or male/female proportion. The median overall survival (mOS) for BRAF MT versus wild-type (WT) patients is 14.0 versus 32.9 months (p = 0.003). For patients who have chemotherapy (plus or minus surgery) the mOS is 14.6 months BRAF MT versus 36.1 months (p ≤ 0.001) WT. Liver or lung resection was performed on only 8% of the BRAF MT group versus 26.5% of the WT group.

CONCLUSION

Results in a population setting confirm our understanding that BRAF MT is more frequently right sided and of lower frequency in rectal cancer. Survival is lower for patients with mCRC that have BRAF MT, regardless of the therapy. BRAF testing is currently performed infrequently in an Australian setting despite its importance as a significant prognostic factor, and the implications for alternate therapeutic approaches.

Metastatic Colorectal Cancer Treatment and Survival: the Experience of Major Public Hospitals in South Australia Over Three Decades

BACKGROUND

Registry data from four major public hospitals indicate trends over three decades from 1980 to 2010 in treatment and survival from colorectal cancer with distant metastases at diagnosis (TNM stage IV).

MATERIALS AND METHODS

Kaplan-Meier product-limit estimates and Cox proportional hazards models for investigating disease-specific survival and multiple logistic regression analyses for indicating first-round treatment trends.

RESULTS

Two-year survivals increased from 10% for 1980-84 to 35% for 2005-10 diagnoses. Corresponding increases in five-year survivals were from 3% to 16%. Time-to-event risk of colorectal cancer death approximately halved (hazards ratio: 0.48 (0.40, 0.59) after adjusting for demographic factors, tumour differentiation, and primary sub-site. Survivals were not found to differ by place of residence, suggesting reasonable equity in service provision. About 74% of cases were treated surgically and this proportion increased over time. Proportions having systemic therapy and/or radiotherapy increased from 12% in 1980-84 to 61% for 2005-10. Radiotherapy was more common for rectal than colonic cases (39% vs 7% in 2005-10). Of the cases diagnosed in 2005-10 when less than 70 years of age, the percentage having radiotherapy and/or systemic therapy was 79% for colorectal, 74% for colon and 86% for rectum (and RS)) cancers. Corresponding proportions having: systemic therapies were 75%, 71% and 81% respectively; radiotherapy were 24%, 10% and 46% respectively; and surgery were 75%, 78% and 71% respectively. Based on survey data on uptake of offered therapies, it is likely that of these younger cases, 85% would have been offered systemic treatment and among rectum (and RS) cases, about 63% would have been offered radiotherapy.

CONCLUSIONS

Pronounced increases in survivals from metastatic colorectal cancer have occurred, in keeping with improved systemic therapies and surgical interventions. Use of radiotherapy and/or systemic therapy has increased markedly and patterns of change accord with clinical guideline recommendations.

The shadow of inequitable conduct in the US patent application

Inequitable conduct regarding any single claim can render the entire patent unenforceable and further damage other related patents and applications in the assignee's patent portfolio. The adverse impact of inequitable conduct significantly became a litigation strategy. The US Federal Circuit (CAFC) observed that inequitable conduct as a patent litigation strategy had become a plague and thus tightened the standard for finding inequitable conduct in a case with full court judges. However, under the shadow of previous adverse impact of inequitable conduct, patent applicants may still submit many marginal related references. This study demonstrates that an applicant even prepared an information disclosure statement (IDS) as many as 50 pages. Actually, under the new standard, inequitable conduct would not further produce significant impact in the US patent system. Thus, a patent applicant need not submit marginal references but should distinguish the prior art from the current application, especially for those listed in the IDS, to avoid the novelty rejection.

Hepatic resection, hepatic arterial infusion pump therapy, and genetic biomarkers in the management of hepatic metastases from colorectal cancer

The liver is the most common site of colorectal cancer metastasis. Fortunately, improvements have been made in the care of patients with colorectal liver metastasis (CRLM). Effective management of CRLM requires a multidisciplinary approach that is tailored to individuals in order to achieve long-term survival, and cure. Resection and systemic chemotherapy provides benefit in selected individuals. An adjunct to resection and/or systemic chemotherapy is the use of hepatic arterial infusion pump (HAIP) therapy. Many studies show HAIP provides benefit for select patients with CRLM. Added to the crucible of a multidisciplinary approach to managing CRLM is the ever growing understanding of tumor biology and genetic profiling. In this review, we discuss the outcomes of resection, systemic therapies and HAIP therapy for CRLM. We also discuss the impact of recent advances in genetic profiling and mutational analysis, namely mutation of KRAS and BRAF, for this disease.

Deficient mismatch repair in colorectal cancer: current perspectives on patient management and future directions

Abstract 

Molecular aberrations leading to colorectal cancer are diverse and heterogeneity exists both at a molecular level and in clinical behavior. Defective mismatch repair (dMMR) is a feature of 15% of colorectal cancers. These are hypermutated tumors, mostly right sided and histopathologically elicit a marked immune response. A proportion of these arise due to germline mutation of a mismatch repair gene giving rise to Lynch syndrome, while the majority arise sporadically due to somatic alteration of the MLH1 mismatch repair gene. Although dMMR is associated with an excellent patient prognosis, as tumor stage advances the frequency of dMMR declines and the association with improved prognosis dissipates. It is apparent that dMMR tumors do not represent a unique molecular subset. As the knowledge of the underlying biology evolves, the hope is for individualized therapy that goes well beyond the crude and oversimplified categorization of dMMR versus proficient MMR.