Cellular Uptake and Efflux of Palbociclib In Vitro in Single Cell and Spheroid Models.

Adequate drug distribution through tumors is essential for treatment to be effective. Palbociclib is a cyclin-dependent kinase 4/6 inhibitor approved for use in patients with hormone receptor positive, human epidermal growth factor receptor 2 negative metastatic breast cancer. It has unusual physicochemical properties, which may significantly influence its distribution in tumor tissue. We studied the penetration and distribution of palbociclib in vitro, including the use of multicellular three-dimensional models and mathematical modeling. MCF-7 and DLD-1 cell lines were grown as single cell suspensions (SCS) and spheroids; palbociclib uptake and efflux were studied using liquid chromatography-tandem mass spectrometry. Intracellular concentrations of palbociclib for MCF-7 SCS (C max 3.22 µM) and spheroids (C max 2.91 µM) were 32- and 29-fold higher and in DLD-1, 13- and 7-fold higher, respectively, than the media concentration (0.1 µM). Total palbociclib uptake was lower in DLD-1 cells than MCF-7 cells in both SCS and spheroids. Both uptake and efflux of palbociclib were slower in spheroids than SCS. These data were used to develop a mathematical model of palbociclib transport that quantifies key parameters determining drug penetration and distribution. The model reproduced qualitatively most features of the experimental data and distinguished between SCS and spheroids, providing additional support for hypotheses derived from the experimental data. Mathematical modeling has the potential for translating in vitro data into clinically relevant estimates of tumor drug concentrations. SIGNIFICANCE STATEMENT: This study explores palbociclib uptake and efflux in single cell suspension and spheroid models of cancer. Large intracellular concentrations of palbociclib are found after drug exposure. The data from this study may aid understanding of the intratumoural pharmacokinetics of palbociclib, which is useful in understanding how drug distributes within tumor tissue and optimizing drug efficacy. Biomathematical modelling has the potential to derive intratumoural drug concentrations from plasma pharmacokinetics in patients.

Drug delivery in a tumour cord model: a computational simulation.

The tumour vasculature and microenvironment is complex and heterogeneous, contributing to reduced delivery of cancer drugs to the tumour. We have developed an in silico model of drug transport in a tumour cord to explore the effect of different drug regimes over a 72 h period and how changes in pharmacokinetic parameters affect tumour exposure to the cytotoxic drug doxorubicin. We used the model to describe the radial and axial distribution of drug in the tumour cord as a function of changes in the transport rate across the cell membrane, blood vessel and intercellular permeability, flow rate, and the binding and unbinding ratio of drug within the cancer cells. We explored how changes in these parameters may affect cellular exposure to drug. The model demonstrates the extent to which distance from the supplying vessel influences drug levels and the effect of dosing schedule in relation to saturation of drug-binding sites. It also shows the likely impact on drug distribution of the aberrant vasculature seen within tumours. The model can be adapted for other drugs and extended to include other parameters. The analysis confirms that computational models can play a role in understanding novel cancer therapies to optimize drug administration and delivery.

Impact of age and medical comorbidity on adjuvant treatment outcomes for stage III colon cancer: a pooled analysis of individual patient data from four randomized, controlled trials.

BACKGROUND: Adjuvant oxaliplatin plus capecitabine or leucovorin/5-fluorouracil (LV/5-FU) (XELOX/FOLFOX) is the standard of care for stage III colon cancer (CC); however, there is disagreement regarding oxaliplatin benefit in patients aged >70. In most analyses, the impact of medical comorbidity (MC) has not been assessed. Efficacy and safety of adjuvant XELOX/FOLFOX versus LV/5-FU were compared with respect to age and MC using pooled data from four randomized, controlled trials, selected for access to patient-level MC data and including commonly endorsed and utilized regimens. PATIENTS AND METHODS: Individual data from patients with stage III CC in NSABP C-08, XELOXA, X-ACT, and AVANT were pooled, excluding bevacizumab-treated patients. Patients were grouped by treatment, MC (low versus high), or age (<70 versus ≥70), and compared for disease-free survival (DFS), overall survival (OS), and adverse events (AEs). Multivariable Cox proportional hazards regression controlled for gender, T stage, and N stage. RESULTS: DFS benefits were shown for XELOX/FOLFOX versus LV/5-FU regardless of age or MC, although benefits were modestly attenuated for patients aged ≥70. Hazard ratios were 0.68 (P < 0.0001) and 0.77 (P < 0.014) for <70 and ≥70 age groups; 0.69 (P < 0.0001) and 0.59 (P < 0.0001) for Charlson Comorbidity Index ≤1 and >1 groups; and 0.70 (P < 0.0001) and 0.58 (P < 0.0001) for National Cancer Institute Combined Index ≤1 and >1 groups. OS was also significantly improved in all groups. Grade 3/4 serious AE rates were comparable across cohorts and MC scores and higher in patients aged ≥70. Oxaliplatin-relevant grade 3/4 AEs, including neuropathy, were comparable across ages and MC scores. CONCLUSIONS: Results further support consideration of XELOX or FOLFOX as standard treatment options for the adjuvant management of stage III CC in all age groups and in patients with comorbidities, consistent with those who were eligible for these clinical trials.

Mathematical and computational models of drug transport in tumours.

The ability to predict how far a drug will penetrate into the tumour microenvironment within its pharmacokinetic (PK) lifespan would provide valuable information about therapeutic response. As the PK profile is directly related to the route and schedule of drug administration, an in silico tool that can predict the drug administration schedule that results in optimal drug delivery to tumours would streamline clinical trial design. This paper investigates the application of mathematical and computational modelling techniques to help improve our understanding of the fundamental mechanisms underlying drug delivery, and compares the performance of a simple model with more complex approaches. Three models of drug transport are developed, all based on the same drug binding model and parametrized by bespoke in vitro experiments. Their predictions, compared for a 'tumour cord' geometry, are qualitatively and quantitatively similar. We assess the effect of varying the PK profile of the supplied drug, and the binding affinity of the drug to tumour cells, on the concentration of drug reaching cells and the accumulated exposure of cells to drug at arbitrary distances from a supplying blood vessel. This is a contribution towards developing a useful drug transport modelling tool for informing strategies for the treatment of tumour cells which are 'pharmacokinetically resistant' to chemotherapeutic strategies.

'Being there' for women with metastatic breast cancer: a pan-European patient survey.

BACKGROUND: Understanding their experiences of diagnosis is integral to improving the quality of care for women living with advanced/metastatic breast cancer. METHODS: A survey, initiated in March 2011, was conducted in two stages. First, the views of 47 breast cancer-related patient groups in eight European countries were sought on standards of breast cancer care and unmet needs of patients. Findings were used to develop a patient-centric survey to capture personal experiences of advanced breast cancer to determine insights into the 'trade-off' between extending overall survival and side effects associated with its treatment. The second online survey was open to women with locally advanced or metastatic breast cancer, or their carers, and responders were recruited through local patient groups. Data were collected via anonymous local language questionnaires. RESULTS: The online stage II survey received a total of 230 responses from 17 European countries: 94% of respondents had locally advanced or metastatic breast cancer and 6% were adult carers. Although the overall experience of care was generally good/excellent (77%), gaps were still perceived in terms of treatment choice and information provision. Treatment choice for patients was felt to be lacking by 32% of responders. In addition, 68% of those who responded would have liked more information about future medical treatments and research, with 57% wishing to receive this information from their oncologist. Two-thirds (66%) of women with advanced breast cancer, or their carers, believed life-extending treatment to be important so that they can spend more time with family and friends, and 67% said that the treatment was worthwhile, despite potential associated side effects. CONCLUSION: These findings show a continuing need to provide women with advanced breast cancer with better information and emphasise the importance that these patients often place on prolonging survival.

Adjuvant epirubicin followed by cyclophosphamide, methotrexate and fluorouracil (CMF) vs CMF in early breast cancer: results with over 7 years median follow-up from the randomised phase III NEAT/BR9601 trials.

BACKGROUND: The National Epirubicin Adjuvant Trial (NEAT) and BR9601 trials tested the benefit of epirubicin when added to cyclophosphamide, methotrexate and 5-fluorouracil (E-CMF) compared with standard CMF in adjuvant chemotherapy for women with early breast cancer. This report details longer follow-up with interesting additional time-dependent analyses. METHODS: National Epirubicin Adjuvant Trial used epirubicin (E) 3-weekly for four cycles followed by classical (c) CMF for four cycles (E-CMF) compared with cCMF for six cycles. BR9601 used E 3-weekly for four cycles followed by CMF 3-weekly for four cycles, compared with CMF 3-weekly for eight cycles. RESULTS: In all, 2391 eligible patients were randomised and with a median 7.4-year follow-up, E-CMF confirmed a significant benefit over CMF in both relapse-free survival (RFS) (78% vs 71% 5 years RFS, respectively, hazard ratio (HR)=0.75 (95% CI: 0.65-0.86), P<0.0001) and overall survival (OS) (84% vs 78% 5 years OS, respectively, HR=0.76 (95% CI: 0.65-0.89), P=0.0007). Interaction of treatment effect and prognostic factors was demonstrated for duplication of chromosome 17 centromeric enumeration (Ch17CEP) as previously reported. Poor prognostic factors at diagnosis (ER and PR negative and HER2 positive) showed time-dependent annual hazard rates for RFS and OS. In univariate analysis, these factors demonstrated more favourable HRs for RFS after 5 years. Treatment effects also suggested a differential benefit for E-CMF within the first 5 years for poor prognosis tumours. CONCLUSION: Longer follow-up has confirmed E-CMF as significantly superior to CMF for all patients. Ch17CEP duplication was the only biomarker that demonstrated significant treatment interaction. Standard poor prognostic factors at diagnosis were time-dependent, and after 5 years disease-free, poor prognosis patients demonstrated favourable HRs for survival.

Designing phase II trials in cancer: a systematic review and guidance.

BACKGROUND: Literature reviews of cancer trials have highlighted the need for better understanding of phase II statistical designs. Understanding the key elements associated with phase II design and knowledge of available statistical designs is necessary to enable appropriate phase II trial design. METHODS: A systematic literature review was performed to identify phase II trial designs applicable to oncology trials. The results of the review were used to create a library of currently available designs, and to develop a structured approach to phase II trial design outlining key points for consideration. RESULTS: A total of 122 papers describing new or adapted phase II trial designs were obtained. These were categorised into nine levels, reflecting the practicalities of implementation, and form a library of phase II designs. Key design elements were identified by data extraction. Along with detailed description of the key elements and the library of designs, a structured thought process was developed to form a guidance document for choice of phase II oncology trial design. CONCLUSION: The guidance offers researchers a structured and systematic approach to identifying phase II trial designs, highlighting key issues to be considered by both clinicians and statisticians and encouraging an interactive approach to more informed trial design.

A mathematical model of doxorubicin penetration through multicellular layers.

Inadequate drug delivery to tumours is now recognised as a key factor that limits the efficacy of anticancer drugs. Extravasation and penetration of therapeutic agents through avascular tissue are critically important processes if sufficient drug is to be delivered to be therapeutic. The purpose of this study is to develop an in silico model that will simulate the transport of the clinically used cytotoxic drug doxorubicin across multicell layers (MCLs) in vitro. Three cell lines were employed: DLD1 (human colon carcinoma), MCF7 (human breast carcinoma) and NCI/ADR-Res (doxorubicin resistant and P-glycoprotein [Pgp] overexpressing ovarian cell line). Cells were cultured on transwell culture inserts to various thicknesses and doxorubicin at various concentrations (100 or 50 microM) was added to the top chamber. The concentration of drug appearing in the bottom chamber was determined as a function of time by HPLC-MS/MS. The rate of drug penetration was inversely proportional to the thickness of the MCL. The rate and extent of doxorubicin penetration was no different in the presence of NCI/ADR-Res cells expressing Pgp compared to MCF7 cells. A mathematical model based upon the premise that the transport of doxorubicin across cell membrane bilayers occurs by a passive "flip-flop" mechanism of the drug between two membrane leaflets was constructed. The mathematical model treats the transwell apparatus as a series of compartments and the MCL is treated as a series of cell layers, separated by small intercellular spaces. This model demonstrates good agreement between predicted and actual drug penetration in vitro and may be applied to the prediction of drug transport in vivo, potentially becoming a useful tool in the study of optimal chemotherapy regimes.

Improvements in survival for women with breast cancer in Scotland between 1987 and 1993: impact of earlier diagnosis and changes in treatment.

We investigated changes in survival, and their causes, in women with early breast cancer diagnosed in Scotland. The Scottish Cancer Registry identified 1617 and 2077 such women, without metastases at diagnosis who underwent surgery as part of their primary treatment, diagnosed in 1987 and 1993, respectively. There was a statistically significant 11% improvement in 8-year survival between 1987 and 1993. Survival improved across almost all clinical/pathological, treatment and health care delivery/deprivation categories; improvement was not limited to those women diagnosed through the screening programme. In a multivariate model, improved survival appeared to be explained largely by screening and clinical/pathological prognostic factors. Deprivation also had an adverse effect on survival; however, the geographical variation in survival observed for women diagnosed in 1987 was not apparent by 1993. We did not demonstrate a significant independent effect of surgical caseload on survival. We conclude that survival has increased partly as a consequence of screening and earlier diagnosis, but also due to improvements in the organisation and delivery of care.

A cancer research (UK) randomized phase II study of idoxifene in patients with locally advanced/metastatic breast cancer resistant to tamoxifen.

Idoxifene is a novel selective oestrogen receptor modulator (SERM) which had greater binding affinity for the oestrogen receptor (ER) and reduced agonist activity compared with tamoxifen in preclinical studies. In a randomized phase II trial in 56 postmenopausal patients with progressive locally advanced/metastatic breast cancer we assessed whether idoxifene showed evidence of activity compared with an increased 40 mg/day dose of tamoxifen in patients who had previously demonstrated resistance to the standard 20 mg/day dose of tamoxifen. Of 47 patients eligible for response (25 idoxifene, 22 tamoxifen), two partial responses and two disease stabilizations (SD) for >6 months were seen with idoxifene (overall clinical benefit rate 16%, 95% CI 4.5-36.1%). The median duration of clinical benefit was 9.8 months. In contrast, no objective responses were seen with the increased 40 mg/day dose of tamoxifen, although two patients had SD for 7 and 14 months (clinical benefit rate 9%, 95% CI 1.1-29.2%). Idoxifene was well tolerated and the reported possible drug-related toxicities were similar in frequency to those with tamoxifen (hot flushes 13% vs 15%, mild nausea 20% vs 15%). Endocrine and lipid analysis in both groups showed a similar significant fall in serum follicle-stimulating hormone and luteinizing hormone after 4 weeks, together with a significant rise in sex hormone binding globulin levels and 11% reduction in serum cholesterol levels. In conclusion, while idoxifene was associated with only modest evidence of clinical activity in patients with tamoxifen-resistant breast cancer, its toxicity profile and effects on endocrine/lipid parameters were similar to those of tamoxifen.

Protein kinase C: a target for anticancer drugs?

Protein kinase C (PKC) is a family of serine/threonine kinases that is involved in the transduction of signals for cell proliferation and differentiation. The important role of PKC in processes relevant to neoplastic transformation, carcinogenesis and tumour cell invasion renders it a potentially suitable target for anticancer therapy. Furthermore, there is accumulating evidence that selective targeting of PKC may improve the therapeutic efficacy of established neoplastic agents and sensitise cells to ionising radiation. This article reviews the rationale for targeting PKC, focuses on its role in breast cancer and reviews the preclinical and clinical data available for the efficacy of PKC inhibition.

Epirubicin in patients with liver dysfunction: development and evaluation of a novel dose modification scheme.

This study aimed to develop an epirubicin dose modification scheme in women with breast cancer and liver dysfunction. We first identified target areas under the concentration-time curve (AUCs) of 2400 and 1600 ng/ml.h from pharmacokinetic studies in 15 women with normal liver tests. In a second group of 16 women with abnormal liver biochemistry, the relationship between raised asparate aminotransferase (AST) and epirubicin clearance was: dose=AUC (97.5-34.2xlog AST). Adaptive dosing was evaluated prospectively in a third group of 41 women with serum AST > or =2xnormal+/-raised bilirubin. The median AUCs were 2444 and 1608 ng/ml.h, close to the high and low target AUCs, respectively. Variability in AUC was lower with adaptive dosing than in a fourth group given an unadjusted dose of epirubicin (coefficient of variation=25.8, 30.0 and 46.5%, respectively; P=0.06). Epirubicin dosing based on AST is safe and may reduce pharmacokinetic variability.

Oral cancer treatment: developments in chemotherapy and beyond.

Oncology is one of the few areas of medicine where most patients are treated intravenously rather than receiving oral drugs. Recently, several oral anti-cancer drugs have been approved and there are many more in development. Oral chemotherapy is attractive because of its convenience and ease of administration, particularly in the palliative setting. With an increasing number of oral agents emerging, we can expect to see a rapid rise in the use of oral chemotherapy in years to come. This article reviews recent developments in oral chemotherapy, both of traditional cytotoxics and novel, targeted agents, from the viewpoint of patients, physicians, drug developers and health-care providers.

Phase I study of docetaxel in combination with cyclophosphamide as first-line chemotherapy for metastatic breast cancer.

This phase I was study conducted to establish the maximum tolerated dose, dose-limiting toxicity, and recommended dose of docetaxel in combination with cyclophosphamide as first-line chemotherapy for metastatic breast cancer. Twenty-six patients were treated with cyclophosphamide (600 mg m(-2), intravenous bolus) followed by docetaxel (60, 75 or 85 mg m(-2), 1-h intravenous infusion) every 3 weeks. The maximum tolerated dose was docetaxel 85 mg m(-2) with cyclophosphamide 600 mg m(-2), the dose-limiting toxicity being febrile neutropenia. Grade 4 neutropenia was experienced by all patients, but was generally brief. Otherwise, the combination was well tolerated with few acute and no chronic non-haematological toxicities of grade 3/4. Activity was observed at all dose levels and disease sites, and the overall response rate was 42% (95% confidence interval 22-61%). The pharmacokinetics of docetaxel were not modified by cyclophosphamide coadministration. These findings establish a recommended dose of docetaxel 75 mg m(-2) in combination with cyclophosphamide 600 mg m(-2) every three weeks for phase II evaluation.

Which endpoints should we use in evaluating the use of novel fluoropyrimidine regimens in colorectal cancer?

Although significant advances have been made in the treatment of advanced/metastatic colorectal cancer, 5-fluorouracil (5-FU) still forms the basis of chemotherapy. Recently, new 5-FU schedules and novel fluoropyrimidines have been developed, but there are no trials directly comparing these regimens. The current review describes the mechanisms of action, pre-clinical and phase I/II studies of two oral fluoropyrimidine therapies, capecitabine and uracil with tegafur plus leucovorin. It also compares the phase III studies of these agents with those of the two most popular infusional 5-FU-based regimens: de Gramont and German AIO (The Association of Medical Oncology (AIO) of the German Cancer Society). Both oral and infusional regimens demonstrated similar survival to the Mayo Clinic regimen, a standard treatment for colorectal cancer. Therefore, other endpoints must be examined to decide optimum therapy, including response rates, time to disease progression, tolerability and patients' convenience. All four new therapies demonstrated superior safety profiles compared with the Mayo Clinic regimen. However the uracil with tegafur plus leucovorin regimen was associated with severe diarrhoea and capecitabine with hand-foot syndrome. Patients will not sacrifice efficacy for the convenience of oral therapy alone, therefore the fact that capecitabine achieved superior response rates and equivalent time to disease progression compared with the Mayo Clinic regimen, while uracil with tegafur plus leucovorin produced lower response rates and significantly inferior time to disease progression, is highly relevant in choosing treatment.

Topotecan in combination with carboplatin: phase I trial evaluation of two treatment schedules.

BACKGROUND: Topotecan and cisplatin combinations have shown schedule-dependent toxicity, which may in part be due to cisplatin nephrotoxicity. As carboplatin is less nephrotoxic and increasingly replacing cisplatin in clinical practice, the aim of this study was to define the optimal sequence and dose for topotecan in combination with carboplatin. PATIENTS AND METHODS: Two parallel phase I trials, with pharmacokinetic studies, were conducted administering carboplatin on day 1 with topotecan on days 1-5 (schedule A) or days 8-12 (schedule B). repeated every 3 weeks. RESULTS: Twenty-one patients were treated over two dose levels, carboplatin AUC 4 [glomerular filtration rate (GFR) calculated from 51Cr-EDTA clearance] with topotecan 0.5 or 0.75 mg/m2. At the first dose level, six patients were evaluable for each schedule. With schedule A, from 34 cycles, there were two dose reductions and 10 treatment delays due to myelosuppression. With schedule B from 25 cycles, there was one reduction and 10 delays. At dose level 2, both patients in schedule A had dose-limiting neutropenia. In contrast, there was no dose-limiting toxicity with schedule B in six patients, although the majority of cycles were delayed. CONCLUSION: The combination of topotecan and carboplatin using these 3-weekly schedules lead to significant myelotoxicity with attendant dose reductions and delays; the optimal scheduling of these agents remains to be defined.

Follow-up in women with breast cancer: the patients' perspective.

We surveyed the opinions of patients on routine follow-up for early breast cancer to assess their satisfaction with current breast cancer follow-up arrangements, establish the issues that are important to patients in this setting and to assess their opinions on different models of care in breast cancer follow-up. A self-completion questionnaire was issued to 134 women attending an outpatient breast cancer follow-up clinic at a central teaching hospital in Glasgow. Most women (84%) considered follow-up 'important' and 90% were satisfied with current follow-up practice. Almost all patients (91%) were content with both the current frequency and duration of their appointments. Risk of recurrence and effects of treatment were considered the most important topics for discussion. Two-thirds of patients felt it was important to see the same member of staff at each follow-up appointment. The majority (64%) would have been satisfied with a nurse-led system of follow-up, whereas only 38% would be happy with General Practitioner-led care. Although patients are generally satisfied with current follow-up arrangements, most would accept the involvement of specialist nurses in conjunction with a consultant.

Adjuvant ovarian ablation vs CMF chemotherapy in premenopausal breast cancer patients: trial update and impact of immunohistochemical assessment of ER status.

This trial, initiated in 1980, examined the relative values of adjuvant ovarian ablation and chemotherapy comprising cyclophosphamide, methotrexate and 5-fluorouracil (CMF) in premenopausal women with pathological stage II breast cancer. With median follow-up for patients still alive of 13.9 years, there is no difference in survival between women receiving ovarian ablation and CMF (hazard ratio 1.01; 95% CI: 0.74, 1.37). Tumour oestrogen receptor (ER) status was assessed at the time using biochemical ligand-binding assay and retrospectively by immunohistochemistry (IHC). Agreement between these two methods was only fair, but both confirmed the importance of ER status in determining appropriate adjuvant systemic therapy. A statistically significant interaction between IHC quick score and treatment (P=0.001) showed ovarian ablation was more beneficial for patients with a positive quick score, whereas women with a quick score of 0 had a significantly higher risk of death with ovarian ablation (2.33; 95% CI: 1.30, 4.20). We have shown that IHC identifies women with ER 'poor' tumours for whom endocrine manipulation is not appropriate.

Bioavailability study of oral and intravenous OGT 719, a novel nucleoside analogue with preferential activity in the liver.

PURPOSE: Although oral fluoropyrimidine prodrugs are increasingly being administered in preference to intravenous nucleoside analogues in cancer chemotherapy, their activation in malignant liver tissue may be insufficient. OGT 719 (1-galactopyranosyl-5-fluorouracil) is a novel nucleoside analogue, preferentially localized in hepatocytes and hepatoma cells via the asialoglycoprotein receptor. The aim of this study was to assess the systemic bioavailability of this rationally designed drug in 16 patients with advanced solid cancers. METHOD: Crossover pharmacokinetic study of oral (400 or 800 mg) and intravenous (250 mg/m2) OGT 719. RESULTS: Linear pharmacokinetics and oral bioavailability of approximately 25% were observed at the dose levels used in this study. Like other 5-FU prodrugs, considerable interpatient variability was observed in bioavailability following oral dosing. The mean half-life for oral doses was 4 h. OGT 719 was well tolerated. No objective tumour responses were demonstrated. CONCLUSION: The systemic bioavailability and half-life of oral OGT 719 are sufficient to merit dose escalation studies with frequent daily dosing. Subsequent efficacy studies should be performed in patients with primary and secondary liver malignancies.