Clinical development of new drug-radiotherapy combinations.

In countries with the best cancer outcomes, approximately 60% of patients receive radiotherapy as part of their treatment, which is one of the most cost-effective cancer treatments. Notably, around 40% of cancer cures include the use of radiotherapy, either as a single modality or combined with other treatments. Radiotherapy can provide enormous benefit to patients with cancer. In the past decade, significant technical advances, such as image-guided radiotherapy, intensity-modulated radiotherapy, stereotactic radiotherapy, and proton therapy enable higher doses of radiotherapy to be delivered to the tumour with significantly lower doses to normal surrounding tissues. However, apart from the combination of traditional cytotoxic chemotherapy with radiotherapy, little progress has been made in identifying and defining optimal targeted therapy and radiotherapy combinations to improve the efficacy of cancer treatment. The National Cancer Research Institute Clinical and Translational Radiotherapy Research Working Group (CTRad) formed a Joint Working Group with representatives from academia, industry, patient groups and regulatory bodies to address this lack of progress and to publish recommendations for future clinical research. Herein, we highlight the Working Group's consensus recommendations to increase the number of novel drugs being successfully registered in combination with radiotherapy to improve clinical outcomes for patients with cancer.

DNA copy number profiles correlate with outcome in colorectal cancer patients treated with fluoropyrimidine/antifolate-based regimens.

For decades 5-fluorouracil (5-FU) has remained the treatment of choice in the adjuvant and palliative setting of colorectal cancer (CRC). The combinations of 5-FU or its oral prodrug capecitabine with irinotecan/oxaliplatin and the novel agents bevacizumab/cetuximab increased responses. However, the overall prognosis is poor, and predictive biomarkers of cytotoxic drugs activity are missing. Pharmacogenetic studies focused on candidate determinants of drug activity/metabolism, such as thymidylate synthase or dihydropyrimidine dehydrogenase, but reported controversial results. Given the heterogeneous and complex nature of CRC, it is likely that many aberrations underlying its progression can also affect therapeutic response. Therefore, high-throughput arrays for genome-wide-DNA aberrations play a pivotal role for new markers discovery by moving from hypothesis-driven, targeted-research to unbiased screening of the whole genetic spectrum. Chromosomal aberrations are critical events in tumorigenesis, and genomic regions harbouring DNA gains/losses have been identified in 85% of CRC patients. These aberrations change the expression of many genes, which might explain the differential effects of specific chemotherapeutic agents. In particular, recent studies reported correlations between DNA copy-number profiles and response to fluoropyrimidine-based regimens, such as leucovorin-modulated-5-FU+irinotecan (FOLFIRI), capecitabine+irinotecan (CAPIRI) and pemetrexed+irinotecan (ALIRI). Genome-wide profiling by oligonucleotide-based array-comparative-genomic-hybridization (aCGH) revealed genomic loci, of which the copy-number status may serve as marker for outcome after FOLFIRI and CAPIRI. Larger randomized and prospective trials of these aCGH platforms in CRC patients treated with fluoropyrimidine-based regimens are ongoing, and will ultimately demonstrate whether these findings can be of actual value to predict clinical outcome and direct the choice of therapy.

First-time-in-man and pharmacokinetic study of weekly oral perifosine in patients with solid tumours.

AIM: To identify the maximum-tolerated dose (MTD) and pharmacokinetics of oral perifosine. METHODS: Patients with solid tumours received perifosine at dosages ranging from 100-800mg/week. Eligibility criteria included life expectancy>12weeks, WHO performance status2, normal blood, liver and renal functions and no recent anticancer treatment. Drug concentrations were analysed by HPLC-MS/MS. RESULTS: Thirty six patients were recruited (75% males, mean age 54.7years, performance status 1 in 72.2%). Adverse events included nausea (69.4%), diarrhoea (55.6%), vomiting (52.8%) and abdominal pain (13.9%). Antiemetic regimens including glucocorticoids, dopamine antagonists and 5-HT3-antagonists were used as treatment and/or prophylaxis in 50% of the patients. Though MTD was formally not reached with 800mg/week, the treatment discontinuation due to diarrhoea and vomiting likely related to perifosine in two cases led to the decision to stop further dose escalation. Pharmacokinetics after a single dose were median t(max)=8.0-24.2h, median t(1/2)=81.0-115.9h and mean(geo) CL/f=0.28-0.43mL/min/kg. Urinary excretion was below 1%. Perifosine slightly accumulated and steady state was nearly reached after 2-3weeks. CONCLUSION: Oral perifosine was tolerable up to 600mg/week in cancer patients when administered with meal and prophylactic antiemetics. Based on its half-life of about 4days, a weekly regimen may be appropriate.

Pharmacological aspects of the enzastaurin-pemetrexed combination in non-small cell lung cancer (NSCLC).

Conventional regimens have limited impact against NSCLC. Current research is focusing on multiple pathways as potential targets, and this review describes pharmacological aspects underlying the combination of the PKCbeta-inhibitor enzastaurin with the multitargeted antifolate pemetrexed. Pemetrexed is commonly used, alone or combined with platinum compounds, in NSCLC treatment, and ongoing studies are evaluating its target, thymidylate synthase (TS), as predictor of drug activity. Enzastaurin is a biological targeted agent being actively investigated against different tumors as single agent or in combination. All the downstream events following PKCbeta inhibition by enzastaurin are not completely known, and assays to evaluate possible biomarkers, such as expression of PKC, VEGF and GSK3beta, in tissues and/or in blood samples, are being developed. Enzastaurin-pemetrexed combination was synergistic in preclinical models, including NSCLC cells, where enzastaurin reduced phosphoCdc25C, resulting in G2/M-checkpoint abrogation, and Akt and GSK3beta; phosphorylation, favoring apoptosis induction in pemetrexed-damaged cells. Enzastaurin also significantly reduced VEGF secretion and pemetrexed-induced upregulation of TS expression, possibly via E2F-1 reduction, while the combination decreased TS activity. Similarly, the accumulation of deoxyuridine (a marker of TS inhibition) and the reduction of GSK3beta phosphorylation were detectable in clinical samples from a phase-Ib trial of pemetrexed-enzastaurin combination. In conclusion, the favorable toxicity profile and the multiple effects of enzastaurin on signaling pathways involved in cell cycle control, apoptosis and angiogenesis, as well as on proteins involved in pemetrexed activity, provide experimental basis for future studies on enzastaurin-pemetrexed combination and their possible pharmacodynamic markers in NSCLC patients.

Pemetrexed combined with paclitaxel: a dose-finding study evaluating three schedules in solid tumors.

The objectives of this phase I study were to determine the maximum tolerated dose (MTD), recommended phase II dose (RD), antitumor activity, safety, and pharmacokinetics of pemetrexed-paclitaxel combination. Patients (N = 95) with advanced solid tumors were assigned to three schedules (21-day cycles [q21d]). Starting doses for each schedule of pemetrexed and paclitaxel, respectively, were: (S1) 400 and 135 mg/m(2) on d1; (S2) 400 mg/m(2) d1 and 40 mg/m(2) d1 and d8; S3) 400 mg/m(2) d8 and 30 mg/m(2) d1 and d8. MTD was 500/135 mg/m(2) (S1), 400/40 mg/m(2) (S2), and 500/120 mg/m(2) (S3). Most common dose limiting toxicities were febrile neutropenia, fatigue, and neuromotor toxicities. Most common toxicity was grade 3/4 lymphopenia. Four patients had partial response, 43 patients had stable disease. The RD determined was pemetrexed 500 mg/m(2) (d8) and paclitaxel 90 mg/m(2) (d1 and d8), q21d. The combination was well tolerated and showed efficacy in thyroid carcinoma and mesothelioma.

Multiple-pool cell lifespan models for neutropenia to assess the population pharmacodynamics of unbound paclitaxel from two formulations in cancer patients.

PURPOSE: Our objective was to build a mechanism-based pharmacodynamic model for the time course of neutropenia in cancer patients following paclitaxel treatment with a tocopherol-based Cremophor-free formulation (Tocosol Paclitaxel) and Cremophor EL-formulated paclitaxel (Taxol). METHODS: A randomized two-way crossover trial was performed with 35 adult patients who received 175 mg/m(2) paclitaxel as either 15 min (Tocosol Paclitaxel) or 3 h (Taxol) intravenous infusions. Paclitaxel concentrations were measured by LC-MS/MS. NONMEM VI was used for population pharmacodynamics. RESULTS: The cytotoxic effect on neutrophils was described by four mechanism-based models predicated on known properties of paclitaxel that used unbound concentrations in the central, deep peripheral or an intracellular compartment as forcing functions. Tocosol Paclitaxel was estimated to release 9.8% of the dose directly into the deep peripheral compartment (DPC). All models provided reasonable fitting of neutropenic effects. The model with the best predictive performance assumed that this dose fraction was released into 22.5% of the DPC which included the site of toxicity. The second-order cytotoxic rate constant was 0.00211 mL/ng per hour (variability: 52% CV). The relative exposure at the site of toxicity was 2.21 +/- 0.41 times (average +/- SD) larger for Tocosol Paclitaxel compared to Taxol. Lifespan was 11.0 days for progenitor cells, 1.95 days for maturating cells, and 4.38 days for neutrophils. Total drug exposure in blood explained half of the variance in nadir to baseline neutrophil count ratio. CONCLUSIONS: The relative exposure of unbound paclitaxel at the site of toxicity was twice as large for Tocosol Paclitaxel compared to Taxol. The proposed mechanism-based models explained the extent and time course of neutropenia jointly for both formulations.

Mechanistic population pharmacokinetics of total and unbound paclitaxel for a new nanodroplet formulation versus Taxol in cancer patients.

PURPOSE: Our objectives were (1) to compare the disposition and in vivo release of paclitaxel between a tocopherol-based Cremophor-free formulation (Tocosol Paclitaxel) and Cremophor EL-formulated paclitaxel (Taxol) in human subjects, and (2) to develop a mechanistic model for unbound and total paclitaxel pharmacokinetics. METHODS: A total of 35 patients (average +/- SD age: 59 +/-13 years) with advanced non-hematological malignancies were studied in a randomized two-way crossover trial. Patients received 175 mg/m(2) paclitaxel as 15 min (Tocosol Paclitaxel) or 3 h (Taxol) intravenous infusion in each study period. Paclitaxel concentrations were determined by LC-MS/MS in plasma ultrafiltrate and whole blood. NONMEM VI was used for population pharmacokinetics. RESULTS: A linear disposition model with three compartments for unbound paclitaxel and a one-compartment model for Cremophor were applied. Total clearance of unbound paclitaxel was 845 L/h (variability: 25% CV). The prolonged release with Tocosol Paclitaxel was explained by the limited solubility of unbound paclitaxel of 405 ng/mL (estimated) in plasma. The 15 min Tocosol Paclitaxel infusion yielded a mean time to 90% cumulative input of 1.14 +/- 0.16 h. Tocosol Paclitaxel was estimated to release 9.8% of the dose directly into the deep peripheral compartment. The model accounted for the presence of drug-containing nanodroplets in blood. CONCLUSIONS: Population pharmacokinetic analysis indicated linear disposition and a potentially higher bioavailability of unbound paclitaxel following Tocosol Paclitaxel administration due to direct release at the target site. The prolonged release of Tocosol Paclitaxel supports 15 min paclitaxel infusions. This mechanistic model may be important for development of prolonged release formulations that distribute in and from the systemic circulation.

Phase-I-study of four different schedules of pemetrexed, gemcitabine and cisplatin in patients with locally advanced or metastatic solid tumours.

This non-randomised Phase-I-study determined recommended dose (RD) and dose-limiting toxicities (DLTs) of four different schedules combining pemetrexed (P), gemcitabine (G) and cisplatin (C). Patients 18 years with locally advanced/metastatic cancer were enrolled. Doses were escalated for one 21-d (q3w; PGC d1, G d8) and three 28-d schedules (q4wA: PG d1, GC d15; q4wB: GC d1, PC d15; q4wC: PGC d1+15). Starting doses were P 400/500 mg/m(2) (q3w/q4w), G 800 mg/m(2) and C 40 mg/m(2). Sixty patients were enroled (n=12/14/30/4 for q3w/q4wA/q4wB/q4wC). Common cancers included head and neck (n=19), prostate (n=7), sarcoma (n=5) and stomach (n=5). Thirteen patients experienced DLTs, most frequently fatigue (n=4) and neutropenia (n=3). Schedule q4wB reached the highest doses (P 600 mg/m(2) d15; G 1250 mg/m(2) d1; C 70 mg/m(2)d1+15). There were no CRs, 11 PRs and 25 SDs (n=47). The PGC-combination was feasible. The recommended schedule for subsequent studies would be 1250 mg/m(2) G and 60 mg/m(2) C on d1, followed by 500 mg/m(2) P and 60 mg/m(2) C on d15.

Antitumor activity of Titanocene Y against freshly explanted human breast tumor cells and in xenografted MCF-7 tumors in mice.

Bis-[(p-methoxybenzyl)cyclopentadienyl] titanium dichloride, better known as Titanocene Y, is a newly synthesized transition metal-based anticancer drug. We studied the antitumor activity of Titanocene Y with concentrations of 2.1, 21 and 210 micromol/l against a freshly explanted human breast cancer, using an in-vitro soft agar cloning system. The sensitivity against Titanocene Y was highly remarkable in the breast cancer tumor in the full concentration range. Titanocene Y showed cell death induction at 2.1 micromol/l, well comparable to cisplatin, given at a concentration of 1.0 micromol/l. A further preclinical development of Titanocene Y was warranted and therefore an MCF-7 human breast cancer xenograft nonobese diabetic/severe combined immunodeficient mouse model was used. Titanocene Y was given for 21 days at 30 mg/kg/day (75% of the maximum tolerable dose of Titanocene Y), which resulted in the reduction of the tumor volume to around one-third, whereas no mouse was lost because of the surprisingly low toxicity of Titanocene Y.

Antiproliferative activity of Titanocene Y against tumor colony-forming units.

Bis-[(p-methoxybenzyl)cyclopentadienyl] titanium dichloride, better known as Titanocene Y, is a newly synthesized titanium-based anticancer drug. We studied the antitumor activity of Titanocene Y with concentrations of 2.1, 21 and 210 micromol/l against a range of freshly explanted human tumors, using an in-vitro soft agar cloning system. The sensitivity against Titanocene Y was highly remarkable in the case of renal cell, ovarian, nonsmall cell lung and colon cancer. In particular the surprisingly good response of nonsmall cell lung cancer and colon cancer against Titanocene Y at its lowest concentration of 2.1 micromol/l was well comparable or better with respect to cisplatin, given at a concentration of 1.0 micromol/l. Further clinical development of Titanocene Y appears to be warranted because of the broad cytotoxic activity shown and the specific activity of Titanocene Y against renal cell cancer.

Phase 1b dose escalation study of erlotinib in combination with infusional 5-Fluorouracil, leucovorin, and oxaliplatin in patients with advanced solid tumors.

PURPOSE: Erlotinib (Tarceva) is a potent epidermal growth factor receptor (HER1) inhibitor. Infusional 5-fluorouracil (5-FU), leucovorin, and oxaliplatin (FOLFOX) is a standard therapy for colorectal cancer. This trial assessed the maximum tolerated dose (MTD), safety, preliminary efficacy, and pharmacokinetics of erlotinib combined with FOLFOX. EXPERIMENTAL DESIGN: Patients with advanced solid tumors were sequentially enrolled into three cohorts (cohort 1: 100 mg/d erlotinib, 65 mg/m(2) oxaliplatin, 200 mg/m(2) leucovorin, 400 mg/m(2) bolus 5-FU, and 400 mg/m(2) continuous infusion 5-FU; cohort 2: oxaliplatin increased to 85 mg/m(2) and 5-FU infusion increased to 600 mg/m(2); and cohort 3: erlotinib increased to 150 mg/d). RESULTS: Thirty-two patients were enrolled (23 with colorectal cancer): no dose-limiting toxicities (DLT) were observed in cohort 1. In cohort 2, two of nine patients experienced a DLT (both diarrhea). In cohort 3, two of nine patients had a DLT (diarrhea and staphylococcal septicemia). Cohort 3 determined the MTD cohort and expanded to 17 patients in total. The most common adverse events were diarrhea, nausea, stomatitis, and rash (primarily mild/moderate). No pharmacokinetics interactions were observed. One patient (colorectal cancer) had a complete response, seven patients had a partial response, and nine had stable disease. CONCLUSIONS: The MTD was defined as follows: 150 mg/d erlotinib, 85 mg/m(2) oxaliplatin; 200 mg/m(2) leucovorin, 400 mg/m(2) bolus 5-FU, and 600 mg/m(2) infusion 5-FU. At the MTD, the combination was well tolerated and showed antitumor activity, warranting further investigation in patients with advanced colorectal cancer and other solid tumors.

A phase II trial of pemetrexed in advanced breast cancer: clinical response and association with molecular target expression.

PURPOSE: This phase II trial of pemetrexed explored potential correlations between treatment outcome (antitumor activity) and molecular target expression. EXPERIMENTAL DESIGN: Chemonaïve patients with advanced breast cancer received up to three cycles of pemetrexed 500 mg/m2 (10-minute i.v. infusion) on day 1 of a 21-day cycle, with folic acid and vitamin B12 supplementation. Tumors were surgically removed after the last cycle of pemetrexed as clinically indicated. Biopsies were taken at baseline, 24 hours after infusion in cycle 1, and after cycle 3. RESULTS: Sixty-one women (median age, 46 years; range, 32-72 years) were treated and were evaluable for response. Objective response rate was 31%. Simple logistic regression suggested a potential relationship between mRNA expression of thymidylate synthase (TS) and pemetrexed response (P = 0.103). Based on threshold analysis, patients with "low" baseline TS (< or = 71) were more likely to respond to pemetrexed than patients with "high" baseline TS (>71). Expression of baseline dihydrofolate reductase and glycinamide ribonucleotide formyl transferase tended to be higher in responders but this association was not significant (P > 0.311). TS expression increased significantly between baseline and biopsy 2 (P = 0.004) and dropped to near baseline levels at biopsy 3. Conversely, dihydrofolate reductase and glycinamide ribonucleotide formyl transferase decreased after pemetrexed chemotherapy. CONCLUSIONS: Our results suggest a potential association between "low" pretreatment TS expression levels and response to pemetrexed chemotherapy. Future trials examining expression levels of other genes important to the folate pathway and/or breast cancer may identify a more robust multigene profile that can better predict response to this novel antifolate.

Activity of [1,2-di(cyclopentadienyl)-1,2-di(p-N,N-dimethylaminophenyl)-ethanediyl] titanium dichloride against tumor colony-forming units.

[1,2-di(cyclopentadienyl)-1,2-di(p-N,N-dimethylaminophenyl)-ethanediyl] titanium dichloride is a newly synthesized transition metal-based anti-cancer drug. We studied the anti-tumor activity of this drug (final concentrations: 25, 250 and 2,500 micromol/l) against freshly explanted human tumors, using an in vitro soft agar cloning system. A total of eight tumor samples were evaluated using 1-h exposures. Additionally, the breast carcinoma cell line MCF-7 was examined with regard to sensitivity. The tested compound was markedly active against one renal cancer sample, whereas other renal tumors were resistant. Concentration-dependent anti-tumor activity was demonstrated for all samples except for melanoma. At concentrations of 250 micromol/l or less, the compound was less active than cisplatin or equally active at 0.2 microg/ml, whereas at 2,500 micromol/l it showed a significant cytotoxic activity against a wide spectrum of tumor types. The highest activity was observed against renal carcinomas (three of three tumor specimens inhibited at 2,500 micromol/l). Sensitivity was also highly remarkable in the breast cancer cell line MCF-7 inhibited in a range of 25-2,500 micromol/l, whereas melanoma cells seemed to be profoundly resistant. Further clinical development of this drug appears warranted because of the broad cytotoxic activity shown.

Overview of phase I/II pemetrexed studies.

Pemetrexed (Alimta) is an antifolate that is effective in the inhibition of multiple enzyme targets including thymidylate synthase, dihydrofolate reductase, and glycinamide ribonucleotide formyl transferase. The compound has been evaluated in several phase I trials, both as single agent and in combination with other cytotoxic agents. The initial schedule selected for further investigation in phase II trials was pemetrexed 600 mg/m2 as a 10-minute infusion on day 1 every 21 days. During the subsequent phase II development the dose of pemetrexed was adjusted to 500 mg/m2 due to bone marrow and gastrointestinal toxicities. The adjusted dose of pemetrexed was well tolerated throughout the late-phase drug development program. Preclinical evidence suggests that pemetrexed has additive or synergistic activity when combined with many other clinically important anticancer agents, including gemcitabine (Gemzar), fluorouracil, carboplatin (Paraplatin), oxaliplatin (Eloxatin), paclitaxel, and vinorelbine (Navelbine). Dose-limiting toxicities in these studies were primarily hematologic, and there was no evidence of cumulative hematologic toxicity. During the drug development program it was discovered that supplementation with folic acid and vitamin B12 profoundly increased the tolerability of pemetrexed. The studies discussed in this review demonstrate that pemetrexed is well tolerated as a single agent and will be an important contribution to combination chemotherapy regimens.

Translational research with pemetrexed in breast cancer.

Pemetrexed (Alimta) is a novel folate antimetabolite that primarily inhibits the enzymes thymidylate synthase (TS), dihydrofolate reductase (DHFR), and glycinamide ribonucleotide formyl transferase (GARFT), all of which are involved in pyrimidine and purine synthesis. In a phase II trial of patients with T3/4, N0-2 breast cancer, expression of thymidylate synthase (TS), dihydrofolate reductase (DHFR), glycinamide ribonucleotide formyltransferase (GARFT), p53, and c-erb-B2 (at the mRNA or protein level) was examined in tumor biopsy specimens before and 24 hours after the first dose of pemetrexed and after three cycles of single-agent treatment to establish correlations of biomarker levels and changes with clinical outcome and toxicity. Although final data are not available, initial indications are that clinical response may correlate with decreased or low TS expression. The results obtained from clinical data are supported by laboratory results in three cell lines (MDA-231, MCF-7, and ZR-75). These results suggest that in vitro transcript profiling to identify which genes are important predictors of successful cytotoxic chemotherapy, followed by a focused clinical trial to confirm the in vitro results, may be the best approach for translational research.

Pemetrexed: translational research in breast cancer.

Pemetrexed (Alimta; Eli Lilly and Co, Indianapolis, IN) is a novel antifolate/antimetabolite with activity in breast cancer and has well-defined molecular targets, including thymidylate synthase, dihydrofolate reductase, and glycinamide ribonucleotide formyltransferase. In a phase II trial in patients with T3-4, N0-2 breast cancer, expression of thymidylate synthase, dihydrofolate reductase, glycinamide ribonucleotide formyltransferase, p53, and c-erb-B2 (at the mRNA or protein level) is being examined before and 24 hours after the first dose of neoadjuvant pemetrexed and after three cycles of single-agent treatment to establish correlations of biomarker levels and changes with clinical outcome and toxicity. Full biomarker and clinical data are not yet available from this study; however, clinical responses to pemetrexed treatment have been observed in patients. Results of this trial should provide both an idea of the activity of neoadjuvant pemetrexed in breast cancer and information on biomarker association with clinical performance that can be used in the design of additional clinical studies to assess the predictive value of these markers.

Pemetrexed safety and dosing strategy.

Pemetrexed is a novel antifolate/antimetabolite that inhibits several folate-dependent enzymes, including thymidylate synthase, dihydrofolate reductase, and glycinamide ribonucleotide transformylase. As a class, antifolates have been associated with sporadic severe myelosuppression with gastrointestinal toxicity. Although infrequent, a combination of such toxicities carries a high risk of potentially life-threatening complications. Severe toxicity from pemetrexed-based therapy has become more predictable using the vitamin deficiency marker homocysteine and, to a lesser extent, methylmalonic acid. Evidence now suggests that reducing total plasma homocysteine levels by supplementation with folic acid and vitamin B(12) leads to a better safety profile for pemetrexed, while not adversely affecting its efficacy.