Factors affecting the pharmacokinetics of CPT-11: the body mass index, age and sex are independent predictors of pharmacokinetic parameters of CPT-11

Impact of sex on the efficacy and safety of panitumumab plus fluorouracil and folinic acid versus fluorouracil and folinic acid alone as maintenance therapy in RAS WT metastatic colorectal cancer (mCRC). Subgroup analysis of the PanaMa-study (AIO-KRK-0212)

BACKGROUND

Clinical trials in metastatic colorectal cancer (mCRC) are usually conducted irrespective of sex. Sex-associated differences relating to safety and efficacy in the treatment of mCRC, however, are gaining interest.

METHODS

PanaMa investigated the efficacy of panitumumab (Pmab) plus fluorouracil and folinic acid (FU/FA) versus FU/FA alone after induction therapy with six cycles of FU/FA and oxaliplatin plus Pmab in patients with RAS wild-type mCRC. In this post hoc analysis, the study population was stratified for sex. Evaluated efficacy endpoints during maintenance treatment were progression-free survival (PFS, primary endpoint of the trial), overall survival (OS) and objective response rate during maintenance therapy. Safety endpoints were rates of any grade and grade 3/4 adverse events during maintenance therapy.

RESULTS

In total, 165 male and 83 female patients were randomized and treated. Male and female patients showed numerically better objective response rates with Pmab, without reaching statistical significance. Male patients derived a significant benefit from the addition of Pmab to maintenance treatment with regard to PFS [hazard ratio (HR) 0.63; 95% confidence interval (CI) 0.45-0.88; P = 0.006] that was not observed in female patients (HR 0.85; 95% CI 0.53-1.35; P = 0.491). The better PFS for male patients treated with Pmab did not translate into improved OS (HR 0.85; 95% CI 0.55-1.30; P = 0.452). Female patients showed numerically improved OS when treated with Pmab. There was no difference in the total of grade ≥3 adverse events during maintenance regarding sex (P = 0.791). Female patients, however, had a higher rate of any grade nausea, diarrhea and stomatitis.

CONCLUSIONS

In the PanaMa trial, the addition of Pmab to maintenance treatment of RAS wild-type mCRC with FU/FA improved the outcome in terms of the primary endpoint (PFS) particularly in male patients. Female patients did not show the same benefit while experiencing higher rates of adverse events. Our results support the development of sex-specific protocols.

Nomogram for predicting the overall survival of underweight patients with colorectal cancer: a clinical study

BACKGROUND

An underweight individual is defined as one whose Body Mass Index (BMI) is < 18.5 kg/m². Currently, the prognosis in patients with colorectal cancer (CRC) who are also underweight is unclear.

METHODS

Information on South Korean patients who underwent curative resection for CRC without distant metastasis was collected from health insurance registry data between January 2014 and December 2016. We compared the overall survival (OS) of underweight and non-underweight (BMI ≥ 18.5 kg/m²) patients after adjusting for confounders using propensity score matching. A nomogram to predict OS in the underweight group was constructed using the significant risk factors identified in multivariate analysis. The predictive and discriminative capabilities of the nomogram for predicting 3- and 5-year OS in the underweight group were validated and compared with those of the tumor, node, and metastasis (TNM) staging system in the training and validation sets.

RESULTS

A total of 23,803 (93.6%) and 1,644 (6.4%) patients were assigned to the non-underweight and underweight groups, respectively. OS was significantly worse in the underweight group than in the non-underweight group for each pathological stage (non-underweight vs. underweight: stage I, 90.1% vs. 77.1%; stage IIA, 85.3% vs. 67.3%; stage IIB/C, 74.9% vs. 52.1%; and stage III, 73.2% vs. 59.4%, P < 0.001). The calibration plots demonstrated that the nomogram exhibited satisfactory consistency with the actual results. The concordance index (C-index) and area under the receiver operating characteristic curve (AUC) of the nomogram exhibited better discriminatory capability than those of the TNM staging system (C-index, nomogram versus TNM staging system: training set, 0.713 versus 0.564, P < 0.001; validation set, 0.691 versus 0.548, P < 0.001; AUC for 3- and 5- year OS, nomogram versus TNM staging system: training set, 0.748 and 0.741 versus 0.610 and 0.601; validation set, 0.715 and 0.753 versus 0.586 and 0.579, respectively).

CONCLUSIONS

Underweight patients had worse OS than non-underweight patients for all stages of CRC. Our nomogram can guide prognostic predictions and the treatment plan for underweight patients with CRC.

Covalent CES2 Inhibitors Protect against Reduced Formation of Intestinal Organoids by the Anticancer Drug Irinotecan

BACKGROUND

Irinotecan is widely used to treat various types of solid and metastatic cancer. It is an ester prodrug and its hydrolytic metabolite (SN-38) exerts potent anticancer activity. Irinotecan is hydrolyzed primarily by carboxylesterase-2 (CES2), a hydrolase abundantly present in the intestine such as the duodenum. We have identified several potent and covalent CES2 inhibi¬tors such as remdesivir and sofosbuvir. Remdesivir is the first small molecule drug approved for COVID-19, whereas sofosbuvir is a paradigm-shift medicine for hepatitis C viral infection. Irinotecan is generally well-tolerated but associated with severe/life-threatening diarrhea due to intestinal accu¬¬mula¬tion of SN-38.

OBJECTIVE

This study was to test the hypothesis that remdesivir and sofosbuvir protect against irinotecan-induced epithelial injury associated with gastrointestinal toxicity.

METHODS

To test this hypothesis, formation of organoids derived from mouse duodenal crypts, a robust cellular model for intestinal regeneration, was induced in the presence or absence of irinotecan +/- pretreatment with a CES2 drug inhibitor.

RESULTS

Irinotecan profoundly inhibited the formation of intestinal organoids and the magnitude of the inhibition was greater with female crypts than their male counterparts. Consistently, crypts from female mice had significantly higher hydrolytic activity toward irinotecan. Critically, remdesivir and sofosbuvir both reduced irinotecan hydrolysis and reversed irinotecan-reduced formation of organoids. Human duodenal samples robustly hydrolyzed irinotecan, stable CES2 transfection induced cytotoxicity and the cytotoxicity was reduced by CES2 drug inhibitor.

CONCLUSION

These findings establish a therapeutic rationale to reduce irinotecan-gastrointestinal injury and serve as a cellular foundation to develop oral formulations of irinotecan with high safety.

Low lean mass and chemotherapy toxicity risk in the elderly: the Fraction study protocol

Background

Half of cancer cases occur in patients aged 70 and above. Majority of older patients are eligible for chemotherapy but evidence for treating this population is sparse and severe toxicities affect more than half of them. Determining prognostic biomarkers able to predict poor chemotherapy tolerance remains one of the major issues in geriatric oncology. Ageing is associated with body composition changes (increase of fat mass and loss of lean mass) independently of weight-loss. Previous studies suggest that body composition parameters (particularly muscle mass) may predict poor chemotherapy tolerance. However, studies specifically including older adults on this subject remain sparse and the majority of them study body composition based on computed tomography (CT) scanner (axial L3 section) muscle mass estimation. This method is to date not validated in elderly cancer patients.

Methods

This trial (Fraction) will evaluate the discriminative ability of appendicular lean mass measured by dual-energy X-ray absorptiometry (DXA) to predict severe toxicity incidence in older cancer-patients treated with first-line chemotherapy. DXA is considered the gold standard in body composition assessment in older adults.

Patient’s aged ≥70 diagnosed with solid neoplasms or lymphomas at a locally advanced or metastatic stage treated for first-line chemotherapy were recruited. Patients completed a pre-chemotherapy assessment that recorded socio-demographics, tumor/treatment variables, laboratory test results, geriatric assessment variables (function, comorbidity, cognition, social support and nutritional status), oncological risk scores and body composition with DXA. Appendicular lean mass was standardized using evidence based international criteria. Participants underwent short follow-up geriatric assessments within the first 3 months, 6 months and a year after inclusion. Grade 3 to 5 chemotherapy-related toxicities, as defined by the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) were assessed at each chemotherapy cycle.

Discussion

The finding that body composition is associated with poor tolerance of chemotherapy could lead to consider these parameters as well as improve current decision-making algorithms when treating older adults.

Trial registration

ClinicalTrials.gov Identifier: NCT02806154 registered on October 2016.

Clinical and pharmacogenetic determinants of 5-fluorouracyl/leucovorin/irinotecan toxicity: Results of the PETACC-3 trial

PURPOSE

Irinotecan (CPT-11) in combination with 5-fluorouracil (5FU) is widely used in the treatment of colorectal cancer. We assessed potential clinical variables that may predict toxicity and more specifically the role of UGT1A1 polymorphisms associated with irinotecan toxicity. We used data from the PETACC3 trial, which randomised patients in adjuvant setting to 6 months of leucovorin (LV) and 5FU (LV5/FU2) or LV5/FU2 + irinotecan.

PATIENTS AND METHODS

Clinical and toxicity data were available for 2982 patients, DNA was available for 1200 (40%) of these patients. We genotyped the polymorphisms UGT1A1*28 and UGT1A1-3156G > A. Risk factors for neutropenia and diarrhoea were assessed by univariable and multivariable analyses.

RESULTS

In univariable analysis, UGT1A*28 genotype was associated with an increased incidence of grade III-IV neutropenia (incidence: 44% versus 26%; odds ratio [OR]: 2.3; 95% confidence interval [CI]: 1.4-3.7). In multivariable analysis, the most important predictors (ordered in terms of contribution to R²) were baseline neutrophil count (OR for 1-unit (10⁹/l) decrease: 1.8, 95% CI: 1.3-1.7), female sex (OR: 1.8, 95% CI: 1.1-3.0), body surface area (OR for 0.1-unit increase: 0.8, 95% CI: 0.7-1.0), UGT1A1 (OR: 2.8, 95% CI: 1.6-5.0), age (OR per 10 years: 1.3, 95% CI: 1.1-1.6) and poor performance status (OR: 1.6, 95% CI: 1.0-2.6). The main predictors for grade IV neutropenia were sex, age, performance score and UGT1A1. The main predictors for diarrhoea were sex and age.

CONCLUSIONS

We found that a complex of risk factors is involved in the development of toxicity, including UGT1A1. Parameters that are readily available in clinical practice, notably sex, age and performance status, are stronger predictors than the UGT1A1*28 genotype. Further studies beyond the UGT1A1*28 genotype are needed to fully understand the determinants of toxicity risk, notably in females.

GSK-3 inhibition overcomes chemoresistance in human breast cancer

Glycogen Synthase Kinase-3β (GSK-3β), a serine/threonine protein kinase, is an emerging therapeutic target in the treatment of human breast cancer. In this study, we demonstrate that the pharmacological inhibition of GSK-3 by two novel small molecule GSK-3 inhibitors, 9-ING-41 and 9-ING-87, reduced the viability of breast cancer cells but had little effect on non-tumorigenic cell growth. Moreover, treatment with 9-ING-41 enhanced the antitumor effect of irinotecan (CPT-11) against breast cancer cells in vitro. We next established two patient-derived xenograft tumor models (BC-1 and BC-2) from metastatic pleural effusions obtained from patients with progressive, chemorefractory breast cancer and demonstrated that 9-ING-41 also potentiated the effect of the chemotherapeutic drug CPT-11 in vivo, leading to regression of established BC-1 and BC-2 tumors in mice. Our results suggest that the inhibition of GSK-3 is a promising therapeutic approach to overcome chemoresistance in human breast cancer, and identify the GSK-3 inhibitor 9-ING-41 as a candidate targeted agent for metastatic breast cancer therapy.

Body Composition and Anti-Neoplastic Treatment in Adult and Older Subjects - A Systematic Review

BACKGROUND

The estimation of the risk of poor tolerance and overdose of antineoplastic agents protocols represents a major challenge in oncology, particularly in older patients. We hypothesize that age-related modifications of body composition (i.e. increased fat mass and decreased lean mass) may significantly affect tolerance to chemotherapy.

METHOD

We conducted a systematic review for the last 25 years (between 1990 and 2015), using US National library of Medicine Medline electronic bibliographic database and Embase database of cohorts or clinical trials exploring (i) the interactions of body composition (assessed by Dual X-ray Absorptiometry, Bioelectrical Impedance Analyses, or Computerized Tomography) with pharmacokinetics parameters, (ii) the tolerance to chemotherapy, and (iii) the consequences of chemotherapies or targeted therapies on body composition.

RESULTS

Our search identified 1504 articles. After a selection (using pre-established criteria) on titles and abstract, 24 original articles were selected with 3 domains of interest: impact of body composition on pharmacokinetics (7 articles), relationship between body composition and chemotoxicity (14 articles), and effect of anti-cancer chemotherapy on body composition (11 articles). The selected studies suggested that pharmacokinetic was influenced by lean mass, that lower lean mass could be correlated with toxicity, and that sarcopenic patients experienced more toxicities that non-sarcopenic patients. Regarding fat mass, results were less conclusive. No studies specifically explored the topic of body composition in older cancer patients.

CONCLUSIONS

Plausible pathophysiological pathways linking body composition, toxicity, and pharmacokinetics are sustained by the actual review. However, despite the growing number of older cancer patients, our review highlighted the lack of specific studies in the field of anti-neoplastic agents toxicity regarding body composition conducted in elderly.

Sarcopenia is associated with toxicity in patients undergoing neo-adjuvant chemotherapy for oesophago-gastric cancer

BACKGROUND

Patients with potentially curative oesophago-gastric cancer typically undergo neo-adjuvant chemotherapy prior to surgery. The majority of anti-cancer drugs have a narrow therapeutic index. The aim of this study was to determine if features of body composition, assessed using computed tomography (CT) scans, may be predictive of dose-limiting toxicity (DLT) in patients undergoing neo-adjuvant chemotherapy for oesophago-gastric cancer. The influence of sarcopenia and DLT on overall survival was also evaluated.

METHODS

89 Patients having potentially curative oesophago-gastric cancer surgery were studied. Patients studied had histologically confirmed oesophago-gastric cancer with no evidence of distant metastasis on pre-operative staging. CT scan was performed in all cases at diagnosis. DLT was defined as toxicity leading to postponement of treatment, a drug dose reduction or definitive interruption of drug administration.

RESULTS

DLT occurred in 37 out of 89 patients (41.6%) undergoing chemotherapy. Sarcopenia (odds ratio, 2.95; 95% confidence interval, 1.23-7.09; p = 0.015) was associated with DLT on multivariate analysis. Median overall survival for patients who were sarcopenic was 569 days (IQ range: 357-1230 days) vs. 1013 days (IQ range: 496-1318 days) for patients who were not sarcopenic (p = 0.04). There was no significant difference in overall survival in patients who experienced DLT compared with those that did not (p = 0.665).

CONCLUSIONS

Sarcopenia is a significant predictor of DLT in oesophago-gastric cancer patients undergoing neo-adjuvant chemotherapy. These results raise the potential for use of assessment of skeletal muscle mass using CT scans to predict toxicity and individualize chemotherapy dosing.

An integer programming approach for optimal drug dose computation

In this paper, we study the problem of determining the optimal drug administration strategy when only a finite number of different dosages are available, a lower bound is posed on the time intervals between two consecutive doses, and drug concentrations should not exceed the toxic concentration levels. The presence of only binary variables leads to the adoption of an integer programming (IP) scheme for the formulation and solution of the drug dose optimal control problem. The proposed method is extended to account for the stochastic formulation of the optimal control problem, so that it can be used in practical applications where large populations of patients are to be treated. A Finite Impulse Response (FIR) model derived from experimental pharmacokinetic data is employed to correlate the administered drug dose with the concentration-time profiles of the drug in the compartments (organs) of the body.

Body mass index influences the response to infliximab in ankylosing spondylitis

INTRODUCTION

The excess of adipose tissue in obese individuals may have immunomodulating properties and pharmacokinetic consequences. The aim of this study was to determine whether body mass index (BMI) affects response to infliximab (IFX) in ankylosing spondylitis (AS) patients.

METHODS

In 155 patients retrospectively included with active AS, the BMI was calculated before initiation of IFX treatment (5 mg/kg intravenously). After 6 months of treatment, changes from baseline in BASDAI, Visual Analogue Scale (VAS) pain, C-reactive protein (CRP) level, and total dose of nonsteroidal antiinflammatory drug (NSAID) were dichotomized with a threshold corresponding to a decrease of 50% of initial level of the measure, into binary variables assessing response to IFX (BASDAI50, VAS50, CRP50, NSAID50). Whether the BMI was predictive of the response to IFX therapy according to these definitions was assessed with logistic regression.

RESULTS

Multivariate analysis found that a higher BMI was associated with a lower response for BASDAI50 (P = 0.0003; OR, 0.87; 95% CI (0.81 to 0.94)), VAS50 (P < 0.0001; OR, 0.87; 95% CI (0.80 to 0.93)); CRP50 (P = 0.0279; OR, 0.93; 95% CI (0.88 to 0.99)), and NSAID50 (P = 0.0077; OR, 0.91; 95% CI (0.85 to 0.97)), criteria. According to the three WHO BMI categories, similar results were found for BASDAI50 (77.6%, 48.9%, and 26.5%; P < 0.0001), VAS50 (72.6%, 40.4%, and 16.7%; P < 0.0001); CRP50 (87.5%, 65.7%, and 38.5%; P = 0.0001), and NSAID50 (63.2%, 51.5%, and 34.6%; P = 0.06).

CONCLUSIONS

This study provides the first evidence that a high BMI negatively influences the response to IFX in AS. Further prospective studies, including assessment of the fat mass, pharmacokinetics, and adipokines dosages are mandatory to elucidate the role of obesity in AS IFX response.

Influence of body mass index on outcome in advanced colorectal cancer patients receiving chemotherapy with or without targeted therapy

PURPOSE

Obesity is associated with an increased risk of development and recurrence of colorectal cancer. However, the role of obesity in advanced colorectal cancer (ACC) patients is unknown. We investigated the effect of body mass index (BMI) on overall survival (OS) in ACC patients receiving systemic treatment in two large phase III studies (CAIRO and CAIRO2).

PATIENTS AND METHODS

Treatment data were obtained and analysed from 796 ACC patients who were treated with chemotherapy in the CAIRO study, and from 730 ACC patients who were treated with chemotherapy plus targeted therapy in the CAIRO2 study. Baseline height and weight were used to assign patients to one of the following BMI categories: A (<18.5 kg/m(2)), B (18.5-24.9 kg/m(2)), C (25.0-29.9 kg/m(2)) and D (≥30.0 kg/m(2)).

RESULTS

In 796 patients of the CAIRO study a high BMI was associated with better median OS (8.0, 14.9, 18.4 and 19.5 months for BMI categories A, B, C, and D, respectively; P=0.001), and was an independent prognostic factor for OS in a multivariate analysis. BMI was not associated with OS in 730 patients who participated in the CAIRO2 study, although a trend was observed.

CONCLUSIONS

These results show that BMI is an independent prognostic factor for survival in patients receiving chemotherapy, but not in patients receiving chemotherapy and targeted therapy. The possible decreased efficacy of bevacizumab in obese patients may explain this discrepant result. The role of BMI in patients receiving targeted therapy should be further tested.

Low body mass index and sarcopenia associated with dose-limiting toxicity of sorafenib in patients with renal cell carcinoma

BACKGROUND

Patients with severe depletion of skeletal muscle (sarcopenia) are prone to dose-limiting toxicity (DLT) during fluoropyrimidine therapy. We hypothesized that sarcopenia may also predict toxicity of targeted therapy drugs.

MATERIALS AND METHODS

Metastatic renal cell cancer (RCC) patients (n = 55) received sorafenib 400 mg b.i.d. Weight, height and skeletal muscle cross-sectional area at the third lumbar vertebra were measured by computed tomography (CT). Toxicity was assessed.

RESULTS

DLT occurred in 22% of patients overall, of which three-quarters were dose reductions to 400 mg and the remainder entailed termination of treatment. DLT was most common (41%) in sarcopenic patients whose body mass index (BMI) was <25 kg/m(2) and least common (13%) in patients who were not sarcopenic and/or overweight or obese (P = 0.03). Toxicity was especially prevalent in sarcopenic male patients with BMI < 25, with 71% of men with these characteristics being unable to continue treatment at 800 mg/day. By contrast, only 5% of male patients whose muscle index was above the cut-off for sarcopenia and only 11% of male patients whose BMI was >25 experienced a DLT.

CONCLUSION

BMI < 25 kg/m(2) with diminished muscle mass is a significant predictor of toxicity in metastatic RCC patients treated with sorafenib.

Part II: Liver function in oncology: towards safer chemotherapy use

The liver is fundamentally important in drug metabolism. In oncology, the astute clinician must not only understand the meaning and limitations of commonly ordered liver biochemical tests, but also be aware of which anticancer agents might induce liver dysfunction, and of the strategies for appropriate dosing of patients with pre-existing liver dysfunction. In part I of our Review, we highlighted both the importance and inadequacies of identifying serum biochemical liver abnormalities in oncology; we also discussed a lack of routine formal investigation of liver function. We summarised chemotherapy-related hepatotoxicity and other causes of liver toxic effects in patients with cancer. Here in part II, we discuss trials that have specifically assessed chemotherapy dosing strategies in the setting of overt biochemical liver dysfunction and we note their recommendations. Furthermore, we review other assessments of liver metabolic and excretory function, particularly in the setting of chemotherapy drug handling. We discuss the potential use of these metabolic probes in practice.

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.

Being overweight influences the development of hepatic dysfunction in Japanese patients with non-small-cell lung cancer undergoing cytotoxic chemotherapy

PURPOSE

The aim of this study was to identify risk factors for hepatic dysfunction during cytotoxic chemotherapy in Japanese patients with non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

We retrospectively reviewed the medical records of patients with NSCLC who received cytotoxic chemotherapy at Okayama University Hospital between January 2003 and March 2006. "Overweight" was defined as a body mass index (BMI) of 25 or more, according to the World Health Organization (WHO) criteria. We investigated the incidence and pattern of hepatic dysfunction during chemotherapy and evaluated the possible associations between hepatic dysfunction and several clinical factors, including BMI.

RESULTS

Of the 155 Japanese patients enrolled in this study, 19 (12%) were overweight. Grade 2 or worse hepatic dysfunction was observed in 5 of the 19 overweight patients (26%) but in only 13 of the 136 non-overweight patients (10%). A multivariate analysis demonstrated that a higher BMI significantly increased the risk of grade 2 or worse hepatic dysfunction after the initiation of cytotoxic chemotherapy (odds ratio=4.04, 95% confidence intervals: 1.13-14.5, p=0.032).

CONCLUSION

Our data suggest that being overweight can influence the development of hepatic dysfunction in Japanese patients receiving cytotoxic chemotherapy for the treatment of NSCLC, although further investigation is required.

Relationship of Hepatic Functional Imaging to Irinotecan Pharmacokinetics and Genetic Parameters of Drug Elimination

Purpose

The marked variability of irinotecan (Ir) clearance warrants individualized dosing based on hepatic drug handling. The aims of this trial were to identify parameters from functional hepatic nuclear imaging (HNI) that correlate with (1) Ir pharmacology, and (2) single-nucleotide polymorphisms (SNPs) for the ABCB1 (P-glycoprotein) and UGT-1A1 genes, known to influence Ir handling.

Methods

Patients underwent genotyping for ABCB1 SNPs and UTUGT-1A1*28 carriage and HNI with 99mTc-DIDA (acetanilidoiminodiacetic acid)/ 99mTc-DISIDA (disofenin) and MIBI (99mTc-sestamibi) scans, probes for biliary transport proteins ABCC1 and -2, and ABCB1 function. HNI data were analyzed by noncompartmental and deconvolutional analysis to provide hepatic extraction and biliary excretion parameters. Patients received Ir, fluorouracil, and folinic acid using a weekly ×2, every-3-weeks schedule. Plasma was taken for Ir and SN-38 analysis on day 1, cycle 1.

Results

Of the 21 patients accrued, Ir pharmacokinetics data were obtained from 16 patients. 99mTc-DIDA/DISIDA percent retention at 1 hour (1-hour RET) correlated to baseline serum bilirubin (P = .008). Both 99mTc-DIDA/DISIDA and MIBI 1-hour RET correlated with SN-38 area under the curve (AUC; P < .01). On multiple regression analysis, SN-38 AUC = −215 + 18.68 × bilirubin + 4.27 × MIBI 1-hour RET (P = .009, R2 = 44.2%). HNI parameters did not correlate with Ir toxicity or UGT1A1*28 carriage. MIBI excretion was prolonged in patients with the ABCB1 exon 26 TT variant allele relative to wild-type (P = .015).

Conclusion

Functional imaging of hepatic uptake and excretory pathways may have potential to predict Ir pharmacokinetics. Evaluation of a larger cohort as well as polymorphisms in other biliary transporters and UGT1A1 alleles is warranted.

Pharmacology of anticancer drugs in the elderly population

Modifications to bodily functions and physiology are known to occur with age. These changes can have a considerable impact on the pharmacokinetic processes of absorption, distribution, metabolism and excretion and the pharmacodynamic properties of administered drugs. For many drugs with a high therapeutic index, this will be clinically unimportant, but for anticancer drugs, which usually have a low therapeutic index, these pharmacological changes can lead to dramatic consequences, such as excessive drug concentrations and unacceptable toxicity, or subtherapeutic drug concentrations and ineffective treatment. Despite the increased susceptibility of the elderly to these changes, doses are rarely adapted on the basis of pharmacokinetics and pharmacodynamics, with the exception of changes secondary to altered renal function. Until recently, only a few large prospective randomised trials have provided evidence-based data for dose adaptations in elderly patients. However, with increasing knowledge of the pharmacokinetics of anticancer drugs, advances in the knowledge of pharmacokinetic behaviour with aging, and documented efficacy and toxicity data in the elderly population, it is possible to highlight aspects of prescribing anticancer drugs in the elderly. In general, and for most drugs, age itself is not a contraindication to full-dose chemotherapy. The main limiting factors are comorbidity and poor functional status, which may be present in a significant number of the elderly population. Elderly patients with cancer are part of the daily practice of oncologists, but currently clinicians can often only estimate whether dose modification is advantageous for the elderly. This review attempts to elucidate the factors that can influence the pharmacokinetics of anticancer drugs frequently used in the elderly, and the clinical or biochemical parameters that form the basis for dose adjustments with age.

Pharmacology of cytotoxic agents: a helpful tool for building dose adjustment guidelines in the elderly

Aging is associated with multidimensional changes, including alterations in physiological functions, co-morbidities and poly-medications. These changes may lead to modifications in the absorption, distribution, metabolism and excretion of drugs. The lack of a scientific basis for optimal drug dosing in the elderly is a major problem. The development and validation of guidelines are therefore essential to improve treatment administration and monitoring in elderly patients. Even though it has been widely demonstrated that standard therapies used in adults may be of great benefit in the elderly, there may be a higher incidence of toxicity. This could be avoided by using dosage individualization based on a sound knowledge of the physiological factors implicated in the pharmacokinetic (PK) characteristics of the drugs administered and in their observed pharmacodynamic (PD) effects in each patient. The so-called "population modeling" approach renders such studies feasible by allowing the analysis of PK-PD relationships from sparse observational data.

Colorectal cancer in the elderly: is palliative chemotherapy of value?

Colorectal cancer is a disease of the elderly, with 70% of patients being aged 65 years or older. In Western countries, the total number of elderly patients with this disease is expected to further increase in the future. Since the incidence of adverse physical or socioeconomic conditions in the elderly is higher than in younger patients, a thorough assessment of the patient's suitability for therapy should be performed before a decision is made. Using a Comprehensive Geriatric Assessment (CGA) to subdivide the population of elderly cancer patients into three groups can help to guide treatment decisions. Both in the adjuvant and in the palliative setting, there are sufficient data supporting the use of fluorouracil-based chemotherapy in fit elderly patients who can tolerate cytotoxic treatment. Systemic chemotherapy has been shown to effectively reduce mortality in the adjuvant situation and to be of clinical benefit for patients with metastatic disease in terms of longer survival, control of symptoms and quality of life. In recent years, new substances such as oxaliplatin or irinotecan have shown significant activity in the treatment of patients with metastatic colorectal cancer. However, information on how to guide the use of these new drugs in elderly patients is still lacking. Limited data from clinical trials indicate treatment efficacy in selected elderly patients comparable to that observed in younger patients, with overall manageable toxicity. Clearly, further clinical trials in elderly patients with colorectal cancer are necessary as well as the incorporation of aspects of geriatric medicine into the teaching programme of medical oncologists.