Optimisation of irinotecan dose in the treatment of patients with metastatic colorectal cancer after 5-FU failure: results from a multinational, randomised phase II study

Systems Pharmacology Model of Gastrointestinal Damage Predicts Species Differences and Optimizes Clinical Dosing Schedules

Gastrointestinal (GI) adverse events (AEs) are frequently dose limiting for oncology agents, requiring extensive clinical testing of alternative schedules to identify optimal dosing regimens. Here, we develop a translational mathematical model to predict these clinical AEs starting from preclinical GI toxicity data. The model structure incorporates known biology and includes stem cells, daughter cells, and enterocytes. Published data, including cellular numbers and division times, informed the system parameters for humans and rats. The drug‐specific parameters were informed with preclinical histopathology data from rats treated with irinotecan. The model fit the rodent irinotecan‐induced pathology changes well. The predicted time course of enterocyte loss in patients treated with weekly doses matched observed AE profiles. The model also correctly predicts a lower level of AEs for every 3 weeks (Q3W), as compared to the weekly schedule.

Second-line systemic therapy for metastatic colorectal cancer

BACKGROUND

The therapeutic management of people with metastatic colorectal cancer (CRC) who did not respond to first-line treatment represents a formidable challenge.

OBJECTIVES

To determine the efficacy and toxicity of second-line systemic therapy in people with metastatic CRC.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library 2016, Issue 4), Ovid MEDLINE (1950 to May 2016), Ovid MEDLINE In-process & Other Non-Indexed Citations (1946 to May 2016) and Ovid Embase (1974 to May 2016). There were no language or date of publication restrictions.

SELECTION CRITERIA

Randomized controlled trials (RCTs) assessing the efficacy (survival, tumour response) and toxicity (incidence of severe adverse effects (SAEs)) of second-line systemic therapy (single or combined treatment with any anticancer drug, at any dose and number of cycles) in people with metastatic CRC that progressed, recurred or did not respond to first-line systemic therapy.

DATA COLLECTION AND ANALYSIS

Authors performed a descriptive analysis of each included RCT in terms of primary (survival) and secondary (tumour response, toxicity) endpoints. In the light of the variety of drug regimens tested in the included trials, we could carry out meta-analysis considering classes of (rather than single) anticancer regimens; to this aim, we applied the random-effects model to pool the data. We used hazard ratios (HRs) and risk ratios (RRs) to describe the strength of the association for survival (overall (OS) and progression-free survival (PFS)) and dichotomous (overall response rate (ORR) and SAE rate) data, respectively, with 95% confidence intervals (CI).

MAIN RESULTS

Thirty-four RCTs (enrolling 13,787 participants) fulfilled the eligibility criteria. Available evidence enabled us to address multiple clinical issues regarding the survival effects of second-line systemic therapy of people with metastatic CRC.1. Chemotherapy (irinotecan) was more effective than best supportive care (HR for OS: 0.58, 95% CI 0.43 to 0.80; 1 RCT; moderate-quality evidence); 2. modern chemotherapy (FOLFOX (5-fluorouracil plus leucovorin plus oxaliplatin), irinotecan) is more effective than outdated chemotherapy (5-fluorouracil) (HR for PFS: 0.59, 95% CI 0.49 to 0.73; 2 RCTs; high-quality evidence) (HR for OS: 0.69, 95% CI 0.51 to 0.94; 1 RCT; moderate-quality evidence); 3. irinotecan-based combinations were more effective than irinotecan alone (HR for PFS: 0.68, 95% CI 0.60 to 0.76; 6 RCTs; moderate-quality evidence); 4. targeted agents improved the efficacy of conventional chemotherapy both when considered together (HR for OS: 0.84, 95% CI 0.77 to 0.91; 6 RCTs; high-quality evidence) and when bevacizumab was used alone (HR for PFS: 0.67, 95% CI 0.60 to 0.75; 4 RCTs; high-quality evidence).With regard to secondary endpoints, tumour response rates generally paralleled the survival results; moreover, higher anticancer efficacy was generally associated with worse treatment-related toxicity, with the important exception of bevacizumab-containing regimens, where the addition of the targeted agent to chemotherapy did not result in a significant increase in the rate of SAE. Finally, we found that oral (instead of intravenous) fluoropyrimidines significantly reduced the incidence of adverse effects (without compromising efficacy) in people treated with oxaliplatin-based regimens.We could not draw any conclusions on other debated aspects in this field of oncology, such as ranking of treatments (not all possible comparisons have been tested and many comparisons were based on single trials enrolling a small number of participants) and quality of life (virtually no data available).

AUTHORS' CONCLUSIONS

Systemic therapy offers a survival benefit to people with metastatic CRC who did not respond to first-line treatment, especially when targeted agents are combined with conventional chemotherapeutic drugs. Further research is needed to define the optimal regimen and to identify people who most benefit from each treatment.

High-Dose FOLFIRI plus Bevacizumab in the Treatment of Metastatic Colorectal Cancer Patients with Two Different UGT1A1 Genotypes: FFCD 0504 Study

High-dose FOLFIRI has an acceptable safety profile and promising efficacy. UDP-glucuronosyltransferase: (UGT1A1) polymorphism may be predictive of toxicity and efficacy of irinotecan. This phase II study aimed to evaluate the combination of high-dose FOLFIRI plus bevacizumab in patients with previously untreated metastatic colorectal cancer (MCRC) based on their UGT1A1 genotype. Patients with the UGT1A1 *1/*1 (group 1) or *1/*28 (group 2) genotype received bevacizumab plus high-dose FOLFIRI every 2 weeks. Using the Bryant and Day design with objective response rate and toxicity as the primary endpoints, 54 patients in each group were required with a planned interim analysis after inclusion of 17 patients per group. We planned to stop the trial at the interim analysis if ≤ 7 patients exhibited an objective response (OR) and/or ≥ 3 patients exhibited severe toxicity. At the interim analysis, ORs were higher than the number expected: 52.9% (group 1) and 58.8% (group 2). More than three toxic events occurred in both groups and, according to the interim analysis rule, the trial was closed due to unacceptable toxicity. Recruitment was stopped when 86 patients were included and an analysis on overall population was done for overall survival (OS) and progression-free survival (PFS). The median PFS was 10.7 months (group 1) and 10.4 months (group 2). The median OS was 25.5 months (group 1) and 23.9 months (group 2). This trial does not support the use of the intensive treatment with HD-FOLFIRI plus bevacizumab combination for MCRC in patients with the UGTA1*1/UGT1A1*1 or UGT1A1*1/UGT1A1*28 genotype.

Herbal medicines as adjuvants for cancer therapeutics

In the United States, many patients, including cancer patients, concurrently take prescription drugs and herbal supplements. Co-administration of prescription medicines and herbal supplements may have negative outcomes via pharmacodynamic and pharmacokinetic herb-drug interactions. However, multiple constituents in botanicals may also yield beneficial pharmacological activities. Botanicals could possess effective anticancer compounds that may be used as adjuvants to existing chemotherapy to improve efficacy and/or reduce drug-induced toxicity. Herbal medicines, such as ginseng, potentiated the effects of chemotherapeutic agents via synergistic activities, supported by cell cycle evaluations, apoptotic observations, and computer-based docking analysis. Since botanicals are nearly always administrated orally, the role of intestinal microbiota in metabolizing ginseng constituents is presented. Controlled clinical studies are warranted to verify the clinical utility of the botanicals in cancer chemoprevention.

Alternative treatment options in colorectal cancer patients with 5-fluorouracil- or capecitabine-induced cardiotoxicity

Most chemotherapy regimens in colorectal cancer treatment are 5-fluorouracil (5-FU)/leucovorin or capecitabine-based. Cardiotoxicity is a less common but potentially lethal complication of 5-FU or capecitabine treatment, and some physicians might be unfamiliar with treatment alternatives. Rechallenging should be avoided because it carries a high risk of recurrence of the cardiac symptoms and prophylactic treatment is not always protective. Possible alternative treatment options to be considered are to replace the oral capecitabine or intravenous 5-FU by a 5-FU bolus regimen, by uracil-tegafur or tegafur/gimeracil/oteracil, both oral fluoropyrimidines combining a 5-FU prodrug with a dihydropyrimidine dehydrogenase (DPD) inhibitor, or by raltitrexed, a thymidilate synthase inhibitor whose metabolism is independent of DPD. Patients with advanced colorectal cancer and fluoropyrimidine-induced cardiotoxicity can be treated with other non-fluoropyrimidine related chemotherapy, either as a single agent, combined, or in combination with biological agents. In this report we discuss the different alternative treatment options.

Hepatic arterial infusion with irinotecan, oxaliplatin, and floxuridine plus systemic chemotherapy as first-line treatment of unresectable liver metastases from colorectal cancer

BACKGROUND

The aim of this study was to evaluate the therapeutic efficacy and safety of hepatic arterial infusion (HAI) with irinotecan, oxaliplatin, and floxuridine as a firstline treatment in patients with unresectable liver metastases of colorectal cancer (CRC).

PATIENTS AND METHODS

Individual patients were treated with irinotecan (120 mg/m(2)), oxaliplatin (100 mg/m(2)), and floxuridine (500 mg/m(2)) via tumorsupplying arteries. Intravenous leucovorin (200 mg/day) and floxuridine (300 mg/m(2)/day) were given on days 1-3 after the procedure. The therapeutic courses were repeated every 4-8 weeks. Tumor responses, overall survival, and the time to tumor progression were observed.

RESULTS

204 cumulative cycles of chemotherapy were performed for 31 patients (median 7.0). 19 patients achieved a partial response; in 10 patients the disease stabilized, and in 2 patients the disease progressed, producing an overall response rate of 61.3%. The median survival time was 24.8 months, and the median time to tumor progression was 10.1 months. Frequencies of grade 3-4 neutropenia, diarrhea, elevation of serum bilirubin, elevation of serum transaminases, and vomiting were 6.5, 9.7, 3.2, 19.4, and 90.3%, respectively.

CONCLUSION

This triplecombination chemotherapy as firstline treatment through HAI was well tolerated and effective in patients with unresectable liver metastases of CRC.

Integrating radioembolization with chemotherapy in the treatment paradigm for unresectable colorectal liver metastases

Clinical decisions regarding the treatment of metastatic colorectal cancer require consideration of current and evolving modalities to best achieve prolonged patient survival. Clinical trials have established that for first-line treatment of patients with or without extrahepatic metastases, radioembolization augments the response produced by chemotherapy in patients with unresectable liver metastases. This includes progression-free and overall survivals that compare favorably with phase II to III data of current chemotherapy regimens. The increased response rate with radioembolization and first-line chemotherapy may improve the likelihood for potentially curative hepatic lesion resection or ablation. Application of an innovative multidisciplinary treatment approach that integrates radioembolization and local ablative therapy may enable the benefits of curative hepatic resection to be extended to a broader group of patients.

Phase II and UGT1A1 genotype study of irinotecan dose escalation as salvage therapy for advanced gastric cancer

Background:

To assess the efficacy and safety of individualised dose optimisation of irinotecan monotherapy as salvage treatment for advanced gastric cancer (AGC).

Methods:

A total of 43 patients were enrolled. Intravenous irinotecan (350 mg m⁻²) was administered every 3 weeks. The dose was increased (425 mg m⁻² and 500 mg m⁻²) or decreased (250 mg m⁻²) depending on patient tolerance. UGT1A1 genotypes were determined by direct sequencing of genomic DNA extracted from peripheral blood.

Results:

A total of 183 cycles of irinotecan were administered, with a median of four cycles per patient. The overall response rate was 9.3%, and the disease control rate was 62.8%. Median time to disease progression was 2.8 months, and median overall survival was 8.0 months. Grade 3–4 neutropenia was the most common toxicity (53.5%), and febrile neutropenia was the least common toxicity (4.6%). Compared with defective allele groups, UGT1A1 *1/*1 was associated with a lower incidence of grade 3–4 neutropenia during the first cycle (P=0.018).

Conclusion:

Individualised irinotecan dose escalation based on patient tolerance was not associated with increased toxicity and shows modest activity as salvage chemotherapy for AGC. The role of UGT1A1 genotype in clinical toxicity requires further evaluation.

Independent radiologic review in metastatic colorectal cancer: systematic review and meta-analysis

PURPOSE

To perform a meta-analysis addressing evaluation bias in local radiologic assessment (LRA) of lesions when compared with independent radiologic review (IRR) in randomized controlled trials (RCTs) testing chemotherapy for metastatic colorectal cancer (CRC).

MATERIALS AND METHODS

MEDLINE, EMBASE, ClinicalTrials.gov, the Cochrane Library, and Web sites for major medical meetings were searched for RCTs of chemotherapy for metastatic CRC that reported response evaluation by both LRA and IRR. The risk ratios (RRs) of response in the experimental (RR(exp)) and control (RR(cont)) arms were calculated (response rate in LRA divided by response rate in IRR) for each selected study. The ratio of RR of response was calculated (RR of response of LRA divided by RR of response of IRR). The random-effects model was applied. Meta-regression was used to examine the effect of study characteristics on outcomes.

RESULTS

LRA and IRR results were concordant (13 studies; 7742 patients; ratio of RR of response = 0.97; 95% confidence interval [95% CI]: 0.90, 1.04; P = .35). However, LRA overestimated tumor response independently of therapy allocation (interaction test, P = .81) both in control (RR(cont), 1.163; 95% CI: 1.086, 1.246; P < .001) and experimental (RR(exp), 1.156; 95% CI: 1.093, 1.222; P < .001) therapies. Meta-regression did not show any effect of trial characteristics on effects.

CONCLUSION

LRA yields higher response rates in RCTs testing chemotherapy for metastatic CRC, although there was no sign of bias toward experimental therapy. The need for IRR to control evaluation bias must be reappraised.

Caspase-mediated pro-apoptotic interaction of panaxadiol and irinotecan in human colorectal cancer cells

OBJECTIVES

Panaxadiol is a purified sapogenin of ginseng saponins that exhibits anticancer activity. Irinotecan is a second-line anticancer drug, but clinical treatment with irinotecan is limited due to its side effects. In this study, we have investigated the possible synergistic anticancer effects of panaxadiol and irinotecan on human colorectal cancer cells and explored the potential role of apoptosis in their synergistic activity.

KEY FINDINGS

The combination of panaxadiol and irinotecan significantly enhanced antiproliferative effects in HCT-116 cells (P< 0.05). Cell cycle analysis demonstrated that combining irinotecan treatment with panaxadiol significantly increased the G1-phase fractions of cells, compared with irinotecan treatment alone. In apoptotic assays, the combination of panaxadiol and irinotecan significantly increased the percentage of apoptotic cells compared with irinotecan alone (P<0.01). Increased activity of caspase-3 and caspase-9 was observed after treating with panaxadiol and irinotecan. The synergistic apoptotic effects were supported by docking analysis, which demonstrated that panaxadiol and irinotecan bound two different chains of the caspase-3 protein.

CONCLUSIONS

Data from this study suggested that caspase-3- and caspase-9-mediated apoptosis may play an important role in the panaxadiol enhanced antiproliferative effects of irinotecan on human colorectal cancer cells.

Survival advantage for irinotecan versus best supportive care as second-line chemotherapy in gastric cancer--a randomised phase III study of the Arbeitsgemeinschaft Internistische Onkologie (AIO)

BACKGROUND

The value of second-line therapy for metastatic gastric cancer is unclear. So far there are no randomised phase III data comparing second-line chemotherapy to best supportive care (BSC). In this prospective, multicenter, open label, randomised phase III study we compared irinotecan to BSC to evaluate the impact on survival of second-line chemotherapy.

METHODS

Eligible patients (pts) had metastatic or locally advanced gastro-oesophageal junction or gastric adenocarcinoma, objective tumour progression during or within 6months after first-line chemotherapy and ECOG performance status 0-2. Stratification for time of progression after first-line therapy, ECOG PS and pretreatment secured even distribution of important prognostic factors.

TREATMENT

Arm A: Irinotecan 250mg/m(2)q3w (first cycle) to be increased to 350mg/m(2), depending on toxicity. Arm B: BSC.

FINDINGS

Between 10/2002 and 12/2006 40 pts were randomised. The study was closed prematurely due to poor accrual. Responsefor arm A (19 pts evaluable): No objective responses, SD 53%, PD 47%. Improvement of tumour related symptoms: Arm A 50% of pts, arm B 7%. Overall Survival: (all events in 40 pts have occurred): The hazard ratio for death was reduced to 0.48 (95%CI 0.25-0.92) in the irinotecan-arm (p=0.012). Median survival arm A: 4.0months (95% CI 3.6-7.5), arm B: 2.4months (95% CI 1.7-4.9).

INTERPRETATION

Irinotecan as second-line chemotherapy significantly prolongs overall survival compared to BSC in the studied pts. Second-line chemotherapy can now be considered as a proven treatment option for metastatic or locally advanced gastric cancer.

FUNDING

The study was supported by a research grant from Aventis and Pfizer.

Multi-centre phase II clinical trial of yttrium-90 resin microspheres alone in unresectable, chemotherapy refractory colorectal liver metastases

BACKGROUND

This multi-centre phase II clinical trial is the first prospective evaluation of radioembolisation of patients with colorectal liver metastases (mCRC) who failed previous oxaliplatin- and irinotecan-based systemic chemotherapy regimens.

METHODS

Eligible patients had adequate hepatic, haemopoietic and renal function, and an absence of major hepatic vascular anomalies and hepato-pulmonary shunting. Gastroduodenal and right gastric arteries were embolised before hepatic arterial administration of yttrium-90 resin microspheres (median activity, 1.7 GBq; range, 0.9-2.2).

RESULTS

Of 50 eligible patients, 38 (76%) had received > or =4 lines of chemotherapy. Most presented with synchronous disease (72%), >4 hepatic metastases (58%), 25-50% replacement of total liver volume (60%) and bilateral spread (70%). Early and intermediate (>48 h) WHO G1-2 adverse events (mostly fever and pain) were observed in 16 and 22% of patients respectively. Two died due to renal failure at 40 days or liver failure at 60 days respectively. By intention-to-treat analysis using Response Evaluation Criteria in Solid Tumours, 1 patient (2%) had a complete response, 11 (22%) partial response, 12 (24%) stable disease, 22 (44%) progressive disease; 4 (8%) were non-evaluable. Median overall survival was 12.6 months (95% CI, 7.0-18.3); 2-year survival was 19.6%.

CONCLUSION

Radioembolisation produced meaningful response and disease stabilisation in patients with advanced, unresectable and chemorefractory mCRC.

Prediction of irinotecan and 5-fluorouracil toxicity and response in patients with advanced colorectal cancer

Irinotecan and 5-fluorouracil (5-FU) are used to treat metastatic colorectal cancer. Irinotecan's active metabolite is inactivated by UDP-glucuronosyltransferase 1A1 (UGT1A1), which is deficient in Gilbert's syndrome. Irinotecan and metabolites are transported by P-glycoprotein, encoded by ABCB1. 5-FU targets folate metabolism through inhibition of thymidylate synthase (TYMS). Methylenetetrahydrofolate reductase (MTHFR) generates active folate necessary for haematopoiesis. We retrospectively genotyped 140 Swedish and Norwegian irinotecan and 5-FU-treated colorectal cancer patients from the Nordic VI clinical trial for selected variants of UGT1A1, ABCB1, TYMS and MTHFR. We found an increased risk of clinically relevant early toxicity in patients carrying the ABCB1 3435 T/T genotype, Odds ratio (OR)=3.79 (95% confidence interval (CI)=1.09–13.2), and in patients carrying the UGT1A1^*28/^*28 genotype, OR=4.43 (95% CI=1.30–15.2). Patients with UGT1A1^*28/^*28 had an especially high risk of neutropenia, OR=6.87 (95% CI=1.70–27.7). Patients who had reacted with toxicity during the first two cycles were in total treated with fewer cycles (P<0.001), and less often responded to treatment (P<0.001). Genetic variation in ABCB1 was associated with both early toxicity and lower response to treatment. Carriers of the ABCB1 1236T-2677T-3435T haplotype responded to treatment less frequently (43 vs 67%, P=0.027), and survived shorter time, OR=1.56 (95% CI=1.01–2.45).

Genotype-driven phase I study of irinotecan administered in combination with fluorouracil/leucovorin in patients with metastatic colorectal cancer

PURPOSE We aimed to identify the maximum-tolerated dose (MTD) of irinotecan in patients with cancer with UGT1A1*1/*1 and *1/*28 genotypes. We hypothesize that the patients without the *28/*28 genotype tolerate higher doses of irinotecan. PATIENTS AND METHODS Patients undergoing first-line treatment for metastatic colorectal cancer (CRC) eligible for treatment with irinotecan plus infusional fluorouracil/leucovorin (FOLFIRI) were screened for the UGT1A1*28/*28 genotype and excluded from the study. Fifty-nine white patients with either the *1/*1 or the *1/*28 genotype were eligible for dose escalation of irinotecan. The starting dose of biweekly irinotecan was 215 mg/m(2) for both genotype groups, whereas the dose of infusional fluorouracil was fixed. Pharmacokinetic data of irinotecan and metabolites were also obtained. Results The dose of irinotecan was escalated to 370 mg/m(2) in patients with the *1/*28 genotype and to 420 mg/m(2) in those with the *1/*1 genotype. Dose-limiting toxicities (DLTs) were observed in two of four of *1/*28 patients at 370 mg/m(2) and in two of three of *1/*1 patients at 420 mg/m(2). No DLTs were observed in 10 *1/*28 patients at 310 mg/m(2) and in 10 *1/*1 patients at 370 mg/m(2); hence these dose levels were the MTD for each genotype group. The most common grade 3 to 4 toxicities were neutropenia and diarrhea. The pharmacokinetics of irinotecan and SN-38 exhibit linear kinetics. CONCLUSION The recommended dose of 180 mg/m(2) for irinotecan in FOLFIRI is considerably lower than the dose that can be tolerated when patients with the UGT1A1*28/*28 genotype are excluded. Prospective genotype-driven studies should test the efficacy of higher irinotecan doses in the FOLFIRI schedule.

Colorectal cancer: Irinotecan therapy-following a trail of breadcrumbs?

The optimal therapy for patients with metastatic and treatment-refractory colorectal cancer is controversial. Questions with regard to both the sequence and combinations of different drugs need to be answered by well-designed and adequately powered studies before the most appropriate option for second-line treatment for these patients can be defined.

Racial differences in advanced colorectal cancer outcomes and pharmacogenetics: a subgroup analysis of a large randomized clinical trial

PURPOSE

Racial disparities in colorectal cancer (CRC) survival are documented, but there are few data on comparative response to chemotherapy. A subgroup analysis of a multisite National Cancer Institute-sponsored trial (N9741) was performed comparing outcomes of black and white patients with metastatic CRC receiving uniform treatment.

PATIENTS AND METHODS

Adverse events (AEs), response rate (RR), time to progression (TTP), overall survival (OS), and dose-intensity were examined as a function of self-reported race in 1,412 patients treated with irinotecan/fluorouracil, fluorouracil/oxaliplatin, or irinotecan/oxaliplatin. Pharmacogenetic analysis was performed on 486 patients with blood available for germline DNA analysis.

RESULTS

OS was 1.5 months shorter and TTP was 0.6 months shorter in black than white patients (OS: hazard ratio [HR] = 1.13; 95% CI, 0.90 to 1.42; TTP: HR = 0.91, 95% CI, 0.73 to 1.13); neither difference was statistically significant. RR was significantly higher in whites (41%) than blacks (28%; P = .008). Grade 3 or greater AEs were also higher in whites (48%) than blacks (34%; P = .004). These relationships were maintained in multivariate models adjusting for arm, age, sex, and performance status. There was no difference in dose-intensity of delivered therapy. Significant racial differences in prevalence of pharmacogenetic variants were observed, although small sample size precluded investigating the relationship between treatment, race, and genotype.

CONCLUSION

OS and TTP are similar in black and white patients treated per protocol with standardized therapy for metastatic CRC. However, RR and AEs vary considerably by race. The marked racial differences in relevant pharmacogenetics, a potential explanation for differing RR and AEs, are worthy of future study.

Irinotecan as palliative chemotherapy for metastatic colorectal cancer: evolving tactics following initial treatment

BACKGROUND

Patients with metastatic colorectal cancer (mCRC) who progress despite treatment with fluoropyrimidine and irinotecan or oxaliplatin have diminished survival, but they may derive clinically meaningful benefit from second-line or later chemotherapy.

MATERIALS AND METHODS

Literature from 2000 through mid-2008 on the treatment of patients with unresectable mCRC was reviewed to identify options for chemotherapy-resistant patients with mCRC.

RESULTS AND CONCLUSIONS

A recurring finding is that overall survival increases when patients are exposed to all available active agents throughout their course of care, independent of the line of treatment in which medication is delivered. Sequential administration of agents, including irinotecan, oxaliplatin, bevacizumab, and cetuximab, or, alternatively, deferred administration of various medications in combination, have shown promising efficacy that is at least equivalent to established combination regimens with the same agents. Palliative chemotherapy clearly improves survival in patients with unresectable mCRC, with overall survival recently reaching 28 months.

Current place of high-dose irinotecan chemotherapy in patients with metastatic colorectal cancer

INTRODUCTION

Irinotecan has an important place in the treatment of metastatic colorectal cancer. It was initially administered as monotherapy, but is now generally used in combination with 5-fluorouracil or targeted therapies (cetuximab or bevacizumab), with various doses.

METHODS

We here review the main studies assessing irinotecan doses escalation, and discuss the potent advantages of this escalation.

RESULTS

Several studies have demonstrated a dose-intensity relationship for irinotecan, and high doses (up to 600 mg/m2 as monotherapy, 260 mg/m2 in combination therapy) have been used with satisfactory safety and higher objective response rates. It is possible that, in practice, some patients receive insufficient doses of irinotecan. Dose escalation could be considered in carefully selected patients: young patients with a good performance status and normal liver function. This approach could be useful in patients with liver metastases, which may become resectable in the case of a major tumour response. It is wise to perform UGT1A1 genotyping prior to dose escalation to detect patients at high risk of toxicity (genotype 7/7). The role of another laboratory parameter, which needs to be evaluated is the KRAS status of the tumour. A KRAS mutation confers resistance to cetuximab, which reduces treatment options, especially in first-line. However, in the CRYSTAL trial comparing FOLFIRI to FOLFIRI-cetuximab as first-line therapy, the presence of a KRAS mutation did not appear to influence the efficacy of FOLFIRI. The value of irinotecan dose escalation needs to be determined in this setting.

CONCLUSION

Irinotecan dose escalation is potentially of interest in highly selected patients, but this concept is only based on phase I or II trials and must be validated by a randomized trial. Its value regarding other regimens such as FOLFIRINOX or combinations with targeted therapies also needs to be determined.

Irinotecan in the treatment of elderly patients with advanced colorectal cancer

Irinotecan is an active drug in the first and subsequent lines of chemotherapy for patients with advanced colorectal cancer. Frequently, the elderly patients are excluded from receiving irinotecan alone or in combination, and on many occasions these patients receive an initial reduced dose of this drug. This revision has been focused in the role of irinotecan in elderly patients.

MATERIAL AND METHODS

Data from pharmacokinetic studies, comparative analysis of prospective trials according to age and prospective studies with irinotecan alone or irinotecan-combinations in the elderly have been revised and put into context.

RESULTS

Either pharmacokinetic and clinical data suggest that fit elderly patients may tolerate irinotecan as well as the younger population. Response rate and survival achieved in elderly patients with irinotecan combinations seem to be equivalent to that obtained in younger patients.

CONCLUSION

Elderly patients with advanced colorectal cancer should be carefully evaluated in order to be classified as fit or not fit through a comprehensive geriatric assessment. For the group of fit elderly patients, irinotecan may be used as in the younger population.

DTS-108, a novel peptidic prodrug of SN38: in vivo efficacy and toxicokinetic studies

PURPOSE

Irinotecan is a prodrug converted to the active cytotoxic molecule SN38 predominantly by the action of liver carboxylesterases. The efficacy of irinotecan is limited by this hepatic activation that results in a low conversion rate, high interpatient variability, and dose-limiting gastrointestinal toxicity. The purpose of this study was to evaluate a novel peptidic prodrug of SN38 (DTS-108) developed to bypass this hepatic activation and thus reduce the gastrointestinal toxicity and interpatient variability compared with irinotecan.

EXPERIMENTAL DESIGN

SN38 was conjugated to a cationic peptide (Vectocell) via an esterase cleavable linker. The preclinical development plan consisted of toxicity and efficacy evaluation in a number of different models and species.

RESULTS

The conjugate (DTS-108) is highly soluble, with a human plasma half-life of 400 minutes in vitro. Studies in the dog showed that DTS-108 liberates significantly higher levels of free SN38 than irinotecan without causing gastrointestinal toxicity. In addition, the ratio of the inactive SN38-glucuronide metabolite compared with the active SN38 metabolite is significantly lower following DTS-108 administration, compared with irinotecan, which is consistent with reduced hepatic metabolism. In vivo efficacy studies showed that DTS-108 has improved activity compared with irinotecan. A significant dose-dependent antitumoral efficacy was observed in all models tested and DTS-108 showed synergistic effects in combination with other clinically relevant therapeutic agents.

CONCLUSIONS

DTS-108 is able to deliver significantly higher levels of SN38 than irinotecan, without the associated toxicity of irinotecan, resulting in an increased therapeutic window for DTS-108 in preclinical models. These encouraging data merit further preclinical and clinical investigation.

Renal function as a predictor of irinotecan-induced neutropenia

Although approximately half of the administered dose of irinotecan is recovered in urine, scarce data are available on the association of renal function with irinotecan pharmacokinetics and toxicity. Here, these relationships are investigated in 187 patients treated with irinotecan in a three-weekly schedule. No significant effects on irinotecan pharmacokinetics were found in these patients. However, in 131 patients treated with the registered dose, categorized renal function was related to hematological toxicity. The incidence of grade 3-4 neutropenia decreased as function of creatinine clearance, particularly in nonsmoking patients (P < 0.01). Patients with slower creatinine clearance (35-66 ml/min) had a four-times higher risk of grade 3-4 neutropenia (58% vs. 14%; P < 0.001). This study suggests that pretreatment renal function values are associated with irinotecan-induced neutropenia. A confirmatory analysis is warranted to determine whether measures of renal function should be incorporated in future attempts toward individualized treatment with irinotecan.

Pharmacogenetics of irinotecan: clinical perspectives on the utility of genotyping

Depending upon the UDP glucuronosyltransferase 1A1 (UGT1A1) genotype, patients are more or less susceptible to the risk of severe toxicity of irinotecan. As the US FDA-approved label of irinotecan (CPT-11, Camptosar®) has been recently revised to include UGT1A1 genotype among potential risk factors for toxicity, it is expected that UGT1A1 genotyping will be increasingly used in patients undergoing irinotecan treatment. At present, the label states that *28/*28 (7/7) genotype patients are at higher risk of neutropenia and should be treated at a lower dose of irinotecan. Although effective alternative drugs (i.e., oxaliplatin) exist for metastatic colorectal cancer (the main indication of irinotecan), recent studies have confirmed that irinotecan has an important place in the management of this disease. We feel that now is the time for addressing questions around the UGT1A1*28 testing that many oncologists might have had but remained unanswered. For example, does the test have adequate sensitivity/specificity? Can the test results be effectively utilized to guide therapy of metastatic colorectal cancer patients? Is it possible that the *1/*1 (6/6) patients are underdosed? How can the genetic prediction of irinotecan toxicity be improved? Is the UGT1A1*28 test fully predictive of the UGT1A1 deficiency in patients who are not of Caucasian origin? Clinicians and investigators interested in a discussion of each of these points could find this article a useful source.

Multicentre phase II study using increasing doses of irinotecan combined with a simplified LV5FU2 regimen in metastatic colorectal cancer

PURPOSE

Irinotecan at 180 mg/m2 combined with an infusional 5-fluorouracil/leucovorin (5-FU/LV) regimen (FOLFIRI) is a standard first line therapy for metastatic colorectal cancer (mCRC). This phase II study aimed to assess whether increasing the irinotecan dose in the first line FOLFIRI regimen would benefit mCRC patients.

PATIENTS AND METHODS

Patients received FOLFIRI every 2 weeks for up to six cycles, comprising a 5-FU/LV regimen combined with irinotecan at 180 mg/m2 (cycle 1), increasing to 220 mg/m2 (cycle 2) and 260 mg/m2 (cycle 3 and subsequent cycles) dependent on toxicity. Efficacy and safety were determined in the intention to treat (ITT) population and in patients able to receive irinotecan at 260 mg/m2 for at least four cycles [high-dose (HD) population].

RESULTS

Fifty-four eligible patients were included. Among them, 44 (81.5%) formed the HD population. The ITT objective response rate was 48% (90%CI: 36-60) with 25/26 of the responses in the HD population. The disease control rate was 76% (90%CI: 65-85) and median overall survival was 20.4 months (90%CI: 6.4-27.1). The main grade 3/4 toxicities (ITT/HD populations) were neutropenia (61%/59%), and diarrhoea (18%/11%), respectively.

CONCLUSIONS

This study confirms the feasibility of increasing the standard dose of the irinotecan component of FOLFIRI to 260 mg/m2, for more than 80% of patients but does not support a clear advantage of this strategy on unselected mCRC patients.

Irinotecan, oxaliplatin and raltitrexed for the treatment of advanced colorectal cancer

Out of every 17-18 individuals in the US, one develops colorectal cancer (CRC) in their lifetime. Of individuals diagnosed with CRC, > 50% present or develop metastatic disease, which, if untreated, is associated with 6-9 months median survival. Although surgical resection is the primary treatment modality for CRC, chemotherapy is the mainstay of treatment for metastatic or unresectable disease. For nearly three decades, 5-fluorouracil (5-FU) has been the chemotherapy of choice for treatment of CRC. However, the response rates to single 5-FU therapy have been suboptimal with an objective tumour response of 10-20%. Attempts have been made to improve the efficacy of 5-FU by either schedule alteration (protracted infusion versus intravenous push) or biochemical modulation with leucovorin (LV). Continuous infusion induced more tumour regression and prolonged the time-to-disease progression with some significant impact on survival (11.3 versus 12.1 months; p < 0.04). 5-FU/LV resulted in a significant increase in overall response rates and in the prolongation of disease-free survival in the adjuvant setting, although severe toxicities represent a major clinical problem. The last 10 years have seen the addition of several new agents such as irinotecan, oxaliplatin, raltitrexed, bevacizumab and cetuximab. The prognosis has significantly improved with the addition of these agents, with median survivals now > 20 months. This review paper focuses on irinotecan, oxaliplatin and raltitrexed when used alone and in combination.

Treatment of colorectal cancer in the elderly: a review of the literature

Although major progress has been achieved in the treatment of colorectal cancer, there are still several questions open for discussion concerning the management of elderly colorectal cancer patients. We conducted a review of the available literature concerning the use of adjuvant chemotherapy, palliative chemotherapy and surgery in elderly patients with colorectal cancer, using data from meta-analyses, non-systematic reviews and individual trials. All report similar survival benefits with adjuvant and palliative chemotherapy in elderly patients in comparison with younger age groups. Data on treatment-related side effects did not reveal a different toxicity profile for elderly patients. Efficacy and safety data were similar but more difficult to interpret concerning surgery, so this review is inconclusive about the proper use of this treatment modality in the elderly population. It is demonstrated that there is significant gain from chemotherapy in the adjuvant and palliative management of colorectal cancer patients irrespective of age. We, therefore, conclude that all patients should receive the most intensive treatment thought to be effective and safe, according to their biological age and comorbidities.