Phase I study of 5-fluorouracil and leucovorin by a 14-day circadian infusion in metastatic adenocarcinoma patients

Disrupting Circadian Rhythm via the PER1-HK2 Axis Reverses Trastuzumab Resistance in Gastric Cancer

Trastuzumab is the only approved targeted drug for first-line treatment of HER2-positive advanced gastric cancer, but the high rate of primary resistance and rapid emergence of secondary resistance limit its clinical benefits. We found that trastuzumab-resistant (TR) gastric cancer cells exhibited high glycolytic activity, which was controlled by hexokinase 2 (HK2)-dependent glycolysis with a circadian pattern [higher at zeitgeber time (ZT) 6, lower at ZT18]. Mechanistically, HK2 circadian oscillation was regulated by a transcriptional complex composed of PPARγ and the core clock gene PER1. In vivo and in vitro experiments demonstrated that silencing PER1 disrupted the circadian rhythm of PER1-HK2 and reversed trastuzumab resistance. Moreover, metformin, which inhibits glycolysis and PER1, combined with trastuzumab at ZT6, significantly improved trastuzumab efficacy in gastric cancer. Collectively, these data introduce the circadian clock into trastuzumab therapy and propose a potentially effective chronotherapy strategy to reverse trastuzumab resistance in gastric cancer.

SIGNIFICANCE

In trastuzumab-resistant HER2-positive gastric cancer, glycolysis fluctuates with a circadian oscillation regulated by the BMAL1-CLOCK-PER1-HK2 axis, which can be disrupted with a metformin-based chronotherapy to overcome trastuzumab resistance.

Systems Chronotherapeutics

Chronotherapeutics aim at treating illnesses according to the endogenous biologic rhythms, which moderate xenobiotic metabolism and cellular drug response. The molecular clocks present in individual cells involve approximately fifteen clock genes interconnected in regulatory feedback loops. They are coordinated by the suprachiasmatic nuclei, a hypothalamic pacemaker, which also adjusts the circadian rhythms to environmental cycles. As a result, many mechanisms of diseases and drug effects are controlled by the circadian timing system. Thus, the tolerability of nearly 500 medications varies by up to fivefold according to circadian scheduling, both in experimental models and/or patients. Moreover, treatment itself disrupted, maintained, or improved the circadian timing system as a function of drug timing. Improved patient outcomes on circadian-based treatments (chronotherapy) have been demonstrated in randomized clinical trials, especially for cancer and inflammatory diseases. However, recent technological advances have highlighted large interpatient differences in circadian functions resulting in significant variability in chronotherapy response. Such findings advocate for the advancement of personalized chronotherapeutics through interdisciplinary systems approaches. Thus, the combination of mathematical, statistical, technological, experimental, and clinical expertise is now shaping the development of dedicated devices and diagnostic and delivery algorithms enabling treatment individualization. In particular, multiscale systems chronopharmacology approaches currently combine mathematical modeling based on cellular and whole-body physiology to preclinical and clinical investigations toward the design of patient-tailored chronotherapies. We review recent systems research works aiming to the individualization of disease treatment, with emphasis on both cancer management and circadian timing system–resetting strategies for improving chronic disease control and patient outcomes.

Circadian variation in plasma 5-fluorouracil concentrations during a 24 hour constant-rate infusion

Background

Varying the rate of continuous intravenous infusions of 5-fluorouracil (5FU) chemotherapy over a 24-hour period has been reported to improve patient outcomes. It has been hypothesized that circadian variation in drug disposition is a contributing factor. We analyzed 5-FU concentrations during a 24-hour continuous 5-FU infusion.

Methods

Sixty-four subjects with advanced malignancies including pancreatic, hepatocellular, colorectal as well as other epithelial malignancies and either abnormal hepatic or renal function were treated on a phase I and pharmacokinetic study of weekly 24-hour intravenous infusions of 5-FU and leucovorin. No other concomitant anticancer therapy was administered. Blood samples were collected every three hours from 61 subjects for measurement of plasma 5-FU during the first two weekly infusions.

Results

After adjusting for differences in dose, elapsed time from start of infusion and infusion number (2 versus 1), mean 5-FU concentration was highest at 6 am and lowest at 3 pm, with an overall change in the mean from 3 pm to 6 am of +20 percent (95% CI = 12–28%). However, this variation in mean concentration associated with time of day was comparable in magnitude to the between-patient differences, within-patient differences between infusions, and the residual variation within infusion (coefficient of variation = 21%).

Conclusions

Our data show systematic variation by time of day in plasma concentrations of 5-FU administered at a constant rate over 24 hours, but it is small compared to the total variation in plasma concentration contributed by other sources. Circadian variation in men was more pronounced than in women.

Clinical experience with chronomodulated infusional 5-fluorouracil chemoradiotherapy for pancreatic adenocarcinoma

PURPOSE

To evaluate retrospectively the efficacy and chronic toxicities of concurrent radiotherapy and chronomodulated infusion 5-fluorouracil (5-FU) in patients with pancreatic adenocarcinoma.

METHODS AND MATERIALS

Twenty-eight patients with pancreatic adenocarcinoma were treated between January 1997 and May 2000 with 5-FU chronomodulated chemoradiotherapy. Chronomodulated delivery of chemotherapy was chosen on the basis of a lower toxicity profile in the treatment of GI malignancies. The median age was 64 years. Of the 28 patients, 12 were men and 16 were women. Eight patients had unresectable disease and 20 were treated after pancreatic resection. The median radiation dose was 50.4 Gy given in 28 fractions. The median field length and width was 10.6 cm and 10.9 cm, respectively. Concurrent chemotherapy with 5-FU was administered 5 d/wk, with a median total dose of 8.4 g/m2 (300 mg/m2/d). Chronomodulated 5-FU delivery consisted of a low basal infusion for 16 h followed by an 8-h escalating-deescalating infusion peaking at 10 pm. Survival and recurrence data were evaluated using Kaplan-Meier actuarial analysis. Toxicities were recorded using the Radiation Therapy Oncology Group grading system.

RESULTS

The median follow-up for all patients was 26 months (range, 4-68 months). The median overall survival for the 20 patients treated postoperatively was 34 months, with a 3- and 5-year actuarial survival rate of 40% and 21%, respectively. If the 3 patients with carcinoma of the ampulla were removed from the data set, the mean overall survival in the resected patients was 34 months, with a 3-year and 5-year actuarial survival rate of 40% and 17%, respectively. The 8 unresectable patients had a median overall survival of 14 months, and none lived past 2 years. No patient experienced Grade 3 or 4 hematologic toxicity or weight loss. Five patients had nausea and dehydration requiring i.v. fluids; only one (4%) was hospitalized. Four patients required a dose reduction of 5-FU, one for nausea, one for a transient ischemic attack, one for an infection, and one because of myocardial infarction. Seven resected patients, four of whom had no evidence of disease, developed diabetes mellitus 1-2 years after radiotherapy.

CONCLUSION

Chronomodulated 5-FU administration, based on the concept of chronotolerance, has relatively low acute toxicity. Our median survival rate was greater than that after most chemoradiotherapy programs that result in more acute toxicity. Additional study is warranted to evaluate chronomodulated radiosensitizing chemotherapy schedules in prospective trials and with attention to late effects after radiotherapy, including diabetes mellitus.

Phase I study of 5-fluorouracil and leucovorin by continuous infusion chronotherapy and pelvic radiotherapy in patients with locally advanced or recurrent rectal cancer

PURPOSE

To determine the maximal tolerated dose of chronomodulated 5-fluorouracil (5-FU) and leucovorin (LV) given concurrently with radiotherapy in patients with rectal cancer.

METHODS AND MATERIALS

Forty-five patients with T3, T4 or recurrent rectal cancer received concurrent radiotherapy to a minimal dose of 4500 cGy. Chemotherapy was administered by a programmable pump in chronomodulated fashion, with 62.5% of the total dose given within 7 hours around 9:30 pm. The starting doses were LV at 5 mg/m2/d and 5-FU at 150 mg/m2/d. LV was escalated in 5-mg/m2 increments to 20 mg/m2/d; 5-FU was then escalated in 25 mg/m2 increments to the maximal tolerated dose.

RESULTS

Diarrhea and stomatitis were dose limiting, with Grade 3 or worse toxicity occurring in 16% and 5% of patients, respectively. Thirty-seven patients (84%) received their scheduled dose of radiotherapy (range, 4500-6000 cGy). Thirty-two patients had clinical T3 disease; all were treated with definitive surgery; 23 (71%) underwent sphincter-sparing surgery with complete resection in 28 (87%). Ten patients (31%) had no evidence of tumor in the pathologic specimen.

CONCLUSION

Preoperative chemoradiotherapy in rectal cancer using chronomodulated 5-FU and LV is feasible. The recommended Phase II dose is 5-FU 200 mg/m2 and LV 20 mg/m2 daily for 5 weeks.

Chronotherapy of colorectal cancer

Chronotherapy consists of chemotherapy delivery according to circadian rhythms. These genetically based rhythms modulate cellular metabolism and cell proliferation in normal tissues. As a result, both the host tolerance and antitumor efficacy of 5-fluorouracil (5-FU) and oxaliplatin (L-OHP), like 30 other anticancer drugs, vary largely according to the dosing time in laboratory rodents. The transfer of this concept to the clinic is aimed primarily at increasing the dose-intensity of the therapy through adjustment of drug-delivery to 24h rhythms in host tolerance. A specific technology (programmable-in-time infusion pumps) enables administration of chronotherapy to fully ambulatory patients. Phase I-III clinical trials show chronotherapy significantly increases tolerance to high doses of cancer drugs and improves antitumor activity in patients with metastatic colorectal cancer. These safe conditions of drug-delivery led to the first demonstration of the high activity of the 5-FU-leucovorin-L-OHP protocol. Chronotherapy with these three drugs also allows surgical removal of previously unresectable liver and lung metastases. This novel medico-surgical management provides hope for the cure of metastatic disease in patients with unresectable colorectal cancer metastases.

N-(phosphonacetyl)-L-aspartate and calcium leucovorin modulation of fluorouracil administered by constant rate and circadian pattern of infusion over 72 hours in metastatic gastrointestinal adenocarcinoma

BACKGROUND

We have reported that N-(phosphonacetyl)-L-aspartic acid (PALA) 1266 mg/m2 can safely be given 24 hours prior to the start of a 72-hour infusion of fluorouracil (FUra) and leucovorin (LV) at doses of 2000 and 500 mg/m2/day. Since inhibition of aspartate carbamoyltransferase (ACTase) activity was evident 4 hours post PALA, we wished to evaluate PALA given 1 hour prior to FUra. Further, we studied the toxicity and pharmacokinetics with FUra given by either fixed- or variable-rate infusion.

PATIENTS AND METHODS

Twenty-seven patients with gastrointestinal tract adenocarcinomas were treated with PALA 1266 mg/m2/15 min followed by a 72-hour infusion of FUra and LV (1750 & 500 mg/m2/day) given by fixed- or variable-rate (peak at 4:00 A.M.).

RESULTS

Clinical toxicity was similar in two consecutive cycles in 17 patients receiving fixed- and variable-rate infusion at the same FUra dose. Overall, grade 3 stomatitis and hand-foot syndrome occurred in 12% and 4% patients receiving fixed- and in 16% and 10.5% of patients receiving variable-rate infusions. Six of 24 evaluable patients (25%) had a partial response. The profile of FUra plasma levels (Cp) over a 24-hour period during fixed- and variable-rate infusions were strikingly different, but the average Cp and area under the concentration-time curves were comparable. ACTase activity was significantly decreased at 4 and 24 hours after PALA (12% and 18% of baseline; P < 0.001), but enzyme activity had recovered to 40% by 72 hours.

CONCLUSIONS

This regimen was active and well tolerated with similar toxicities with FUra given by either fixed- or variable rate infusion. PALA 1266 mg/m2 significantly inhibited ACTase activity for at least 24 hours.

Postoperative concurrent chronomodulated 5-fluorouracil/leucovorin infusion and pelvic radiotherapy for squamous cell carcinoma of the ovary arising from mature cystic teratoma

Primary squamous cell carcinoma (SCC) of the ovary arising from mature cystic teratoma (MCT) is rare. Survival is very poor. Although different postoperative treatments have been tried, none appears to have influenced outcomes. A 44-year-old patient with FIGO stage IIB SCC of the ovary arising in MCT had exploratory laparotomy and left salpingo-oophorectomy, leaving macroscopic residual pelvic disease. Postoperative treatment consisted of a continuous concurrent chronomodulated infusion of 5-fluorouracil 150 mg/m2/day and leucovorin 10 mg/m2/day with 5 weeks of pelvic radiotherapy. Three years after initial surgery, she remains disease and complication free. Given this patient's unusually long disease-free survival and the efficacy of concurrent chemotherapy and radiotherapy in other SCCs, the concurrent circadian treatment approach used for this patient should be explored in other cases of SCC of the ovary.

Tumor chronobiology

Traditionally, drug delivery has meant getting a simple chemical absorbed predictably from the gut or from the site of injection. A second-generation drug delivery goal has been the perfection of continuous constant rate (zero-order) delivery of simple xenobiotic molecules or common hormones. Living organisms are not 'zero-order' in their requirement for or response to drugs. They are predictable resonating dynamic systems, which require different amounts of drug at predictably different times within the circadian cycle in order to maximize desired and minimize undesired drug effects.

Circadian variation of cell proliferation and cell cycle protein expression in man: clinical implications

Most physiological, biochemical and behavioural processes have been shown to vary in a regular and predictable periodic manner with respect to time. This review focuses on the circadian rhythm in cell proliferation in bone marrow and gut and how this is associated with a circadian expression of cell cycle proteins in human oral mucosa. The control of circadian rhythms by the suprachiasmatic nuclei and the evolving understanding of the genetic and molecular biology of the circadian clock is outlined. Finally, the potential clinical impact of chronobiology in cancer medicine is discussed.

Investigation of the comparative toxicity of 5-FU bolus versus 5-FU continuous infusion circadian chemotherapy with concurrent radiation therapy in locally advanced rectal cancer

PURPOSE

To compare the relative toxicities of bolus versus infusional 5-FU chemotherapy administrated concurrently during external beam irradiation in patients with locally advanced rectal cancer following surgical extirpation.

METHODS

A total of 26 eligible patients were retrospectively identified as having been treated for rectal adenocarcinoma at the Stratton VAMC between 1989 and 1997. A comparative analysis of treatment dose intensities, treatment delays and toxicities in these patients was performed.

RESULTS

Significantly less WBC toxicity was observed in the patients receiving infusional 5-FU chemotherapy. The other toxicities, with the exception of skin toxicity, were generally less frequent in the 5-FU infusional group. When the toxicities were corrected for 5-FU dose intensity, to yield toxicity per mg of 5-FU, statistically significant differences were found for hematological toxicity (WBC and platelets), and for gastrointestinal toxicity (frequency and severity of diarrhea and weight loss). The majority of patients receiving infusional 5-FU therapy were treated using a circadian pattern of treatment peaking around the time of the radiation therapy. Patients receiving infusional 5-FU were able to tolerate over twice the dose intensity as those receiving bolus administration. Local recurrence rate in all patients was 3.8% comparing favorably to other reported studies. Distant recurrence frequency was also acceptable at 34.6% for the group.

CONCLUSION

Infusional 5-FU chemotherapy compared with bolus therapy during pelvic radiation minimizes toxicity to the patient while maximizing the dose of 5-FU that can be delivered. As infusional 5-FU therapy during radiation has previously been shown to increase disease free duration and survival, infusional 5-FU should be considered as an acceptable standard of care to prevent local recurrence of rectal adenocarcinoma following its resection. Shaping this infusional 5-FU chemotherapy within the day so that most of the daily dose is delivered around the time of the radiation therapy may further modify the toxic therapeutic ratio of combined modality therapy.

Clinical chronobiology and chronotherapeutics with applications to asthma

The concept of homeostasis (i.e., constancy of the milieu interne) has long dominated the teaching and practice of medicine. Concepts and findings from chronobiology, the scientific study of biological rhythms, challenge this construct. Biological processes and functions are not at all constant; rather, they are organized in time as rhythms with period lengths that range in duration from as short as a second or less to as long as a year. It is the body's circadian (24 h) rhythms that have been researched most intensely. The peak and trough of these rhythms are ordered rather precisely in time to support the biological requirements of activity during the day and sleep at night. The timing of the peak and trough plus the magnitude of variation (amplitude) of physiological and biochemical functions during the 24 h give rise to predictable-in-time, day-night patterns in the manifestation and exacerbation of many common medical conditions. Circadian rhythms also can influence the response of patients to diagnostic tests and therapeutic interventions according to their timing with reference to body rhythms. Rhythms in the pathophysiology of medical conditions and patient tolerance to medications constitute the basis for chronotherapeutics, the timing of treatment in relation to biological rhythm determinants as a means of optimizing beneficial effects and safety. The article discusses recent advances in medical chronobiology and chronotherapeutics and their relevance to clinical medicine in general and the management of asthma in particular. Indeed, since asthma is a disease that exhibits rather profound circadian rhythmicity, investigation of its pathophysiology and therapy necessitates a chronobiologic approach.

Continuous infusion of chemotherapy: focus on 5-fluorouracil and fluorodeoxyuridine

Continuous infusion of chemotherapy is one of the developments to try to improve the treatment of metastatic cancer. There is a sound theoretical rationale to deliver cytotoxic drugs as a continuous infusion. Furthermore, the development of reliable venous access devices and portable infusion pumps enables patients to be treated in an ambulatory setting. This review focuses on the continuous infusion of the most frequently used drugs: 5-fluorouracil (5-FU) and fluorodeoxyuridine (FUDR). An overview is given of both preclinical studies and studies in humans. Continuous infusion of 5-FU and FUDR has proven to be feasible in all studies. However, the results (response rate and especially survival) are rather disappointing. So far, continuous infusion of cytostatic drugs can still be considered as an experimental procedure. Whether protracted, intermittent of circadian modulated continuous infusion is the optimal treatment schedule has still to be proven in future studies. Furthermore, studies are needed to demonstrate whether dose intensity for most tumours is important for treatment outcome. Also, studies are needed to investigate quality of life and economic issues.

A phase I trial of 5-day chronomodulated infusion of 5-fluorouracil and 1-folinic acid in patients with metastatic colorectal cancer

The aim of this phase I study was to establish the maximum tolerated dose (MTD) of 5-fluorouracil (5-FU), administered as a 5-day chronomodulated infusion in combination with 1-folinic acid (FA) to ambulatory metastatic colorectal cancer patients. Consecutive cohorts of 6 patients were given 5-FU and FA infusions from 10.00 p.m. to 10.00 a.m. with peak delivery at 4.00 a.m. by means of a multichannel programmable pump. The FA dose was always the same (150 mg/m2/d). For the first cohort, the 5-FU dose level was 600 mg/m2/d at the first course, escalated by 100 mg/m2 for each subsequent cohort. Intrapatient dose was also escalated by 100 mg/m2 if toxicity was less than grade 2. The courses were repeated every 3 weeks. Thirty-four patients (17 previously treated) received a total of 154 courses. Dose-limiting toxicity consisted of stomatitis and diarrhoea. No significant haematological, cutaneous or cardiac toxicity was encountered. The MTD of 5-FU was reached at the fourth level (first course at 900 mg/m2/d equal to 4500 mg/m2/course) with 5-FU increased to 1100 mg/m2/d (5500 mg/m2/course) in 4 patients. The received 5-FU dose intensity (DI) over the first 3 courses at this level was 1318 mg/m2/week. Thirty-three patients were assessed for response. An objective response was achieved in 1 out of the 13 previously-treated and in 8 out of the 20 previously-untreated patients. The chronomodulated infusion of 5-FU at a dose of 900 mg/m2/d, together with FA at 150 mg/m2/d for 5 days, was safely delivered to out-patients with metastatic colorectal cancer. The low toxic profile and activity of this regimen in previously untreated patients deserves further exploration for the treatment of 5-FU-sensitive tumours.

Arterial therapy of hepatic colorectal metastases

Considerable experience of the treatment of irresectable hepatic colorectal metastases has accumulated over the past three decades. In this review, the rationale for hepatic artery treatment of colorectal metastases to the liver is presented and various access techniques and chemotherapeutic agents for infusion are discussed. Randomized trials of hepatic artery chemotherapy (HAC) are analysed, and the promising results of recent studies combining less toxic and more effective agents are summarized. Continuous infusion pumps provide the most reliable and long-lasting access for HAC. Appropriate surgical techniques and medical management can minimize complications. Although tumour progression is best controlled by HAC, a clear-cut survival advantage has yet to be demonstrated. While hepatic artery infusion chemotherapy cannot yet be recommended outside investigational protocols, the experience gained so far should stimulate further studies.

Antitumour activity, toxicity and inhibition of thymidylate synthase of prolonged administration of 5-fluorouracil in mice

Continuous infusions of 5-fluorouracil (5-FU) are increasingly used in the treatment of cancer. Their optimal use, however, has still to be determined since the availability of suitable animal models is limited. We studied continuous infusions in mice using subcutaneously implanted pellets that release 5-FU over a period of 3 weeks. At the maximum tolerated dose (MTD) (based on the systemic toxicity in healthy animals) we assessed the antitumour activity, haematological toxicity, inhibition of thymidylate synthase (TS) in tumours and the concentration of 5-FU in plasma during the 3-week period. We also studied the addition of leucovorin in different schedules. The dose-limiting toxicity was weight loss, and at the MTD of 10 mg of 5-FU released in 21 days per mouse myelosuppression was tolerable (nadir for leucocytes and thrombocytes was approximately 40% of pretreatment levels). In several independent experiments using the 5-FU-resistant Colon 26 tumour, a good antitumour activity was observed during the first part of the infusion, but thereafter the growth of the tumours resumed; the overall effect of continuous infusions was thus comparable to that of bolus injections. Coadministration of leucovorin did not enhance the therapeutic results; depending on the schedule used, it proved ineffective or only increased toxicity. Similar results were obtained with head and neck squamous cell carcinomas and with the 5-FU-sensitive tumour Colon 38. In Colon 26 tumours the TS activity (FdUMP-binding assay) initially decreased to 20-30% of controls and returned to normal after 11 days. In the catalytic TS assay a slight inhibition was observed for the continuous infusion, followed after 11 days by a marked (4-fold) increase in activity. 5-FU plasma levels varied from 0.1 to 1 microM following a circadian rhythm (with a peak at 6 h after light onset), and were maintained during the entire period. Subcutaneously implanted pellets represent a suitable model to study prolonged administration of 5-FU in mice and to evaluate the effect of modulating agents in laboratory animals before transferring data obtained in vitro to the clinic.

Serum concentrations of 5-fluorouracil achieved with nocturnal constant-rate infusion in patients with disseminated cancer

Nocturnal infusion of 5-fluorouracil (FUra) was performed in nine patients with disseminated cancer. Three gastric, three colon and three breast cancer patients were administered 300 mg/m2 FUra continuously for 10 h per day from 2100 h to 0700 h for more than 20 consecutive days. In the first three patients, who were treated by drip infusion without the use of a volumetric pump, serum FUra concentrations ranged widely, from 27 to 130 ng/ml, even though the rate of administration was re-adjusted four times during the night. The last six patients were treated using a volumetric pump, and FUra concentrations in serum ranged from 175 to 378 ng/ml, and displayed no circadian rhythm. Although the dose intensity and area under the curve of FUra in these patients were high, neither myelosuppression nor other side effects were observed.

Temporal (circadian) and functional relationship between prostate-specific antigen and testosterone in healthy men

OBJECTIVES

To study the circadian relationship between serum prostate-specific antigen (PSA) and total testosterone in men without clinically evident prostate disease.

METHODS

Blood samples were collected every 3 hours for 24 hours (eight per subject) from 11 clinically healthy men, ages 46 to 72 years. PSA was also monitored once a week for 6 weeks in 16 additional healthy men. PSA, testosterone, and age were correlated by linear regression, and 3-hourly PSA and testosterone values normalized to percent of individual mean were analyzed for circadian rhythm by the least squares fit of a 24-hour cosine.

RESULTS

Mean PSA correlated positively (P < 0.001) and testosterone correlated negatively (P = 0.014) with age and inversely with each other (P < 0.001). The mean circadian range of change (ROC) from lowest to highest values for PSA was 0.37 +/- 0.07 ng/mL (28 +/- 9%), and for testosterone it was 202 +/- 23 ng/dL (53 +/- 7%). The mean ROC over 6 weeks was 0.32 +/- 0.04 ng/mL. A significant circadian rhythm was found for PSA (P = 0.011, amplitude = 5.4 +/- 1.8%, acrophase = 5:02 AM; 95% limits, 2:40 to 7:24 PM) and testosterone (P < 0.001, amplitude = 9.4 +/- 1.8%, acrophase = 8:38 AM; 95% limits, 7:12 to 10:04 AM).

CONCLUSIONS

The temporal relationship between circadian rhythms in PSA and testosterone suggests different physiologic states over the 24 hours, which may be of chronopharmacologic interest with regard to dosing time of drugs or hormonal treatments intended to affect prostate growth and function. Within-day variation in PSA is of little diagnostic significance and does not prevent accurate clinical classification when a single specimen is used.

Chronomodulation of chemotherapy against metastatic colorectal cancer. International Organization for Cancer Chronotherapy

Toxic effects of 5-fluorouracil (5-FU) and oxaliplatin (L-OHP), two active drugs against metastatic colorectal cancer, varied by 50% or more according to circadian dosing time in mice or rats. Adaptation of chemotherapy delivery to circadian rhythms (chronotherapy) was assessed in fully ambulatory outpatients, using multichannel programmable pumps. These devices allowed us to reliably test the clinical relevance of such a chronotherapy principle. First, single agent 5-day chronomodulated schedules were devised and assessed in Phase I and II trials with 5-fluorouracil (5-FU, peak delivery at 4:00 h) or oxaliplatin (L-OHP, peak at 16:00 h). Both schedules were then combined, folinic acid (FA) being added, synchronous with 5-FU infusion. This three-drug chronomodulated regimen (chrono-FFL) produced a 58% response rate (95% C.I.: 48-68%) in 93 patients with metastatic colorectal cancer, 46 of whom had previously received chemotherapy. In the first European randomised trial in 92 previously untreated patients, chronomodulated three-drug delivery achieved 53% response, as compared to 32% in those patients receiving flat infusion (P = 0.038). These respective figures were confirmed in a subsequent multicentre randomised trial involving 186 additional patients. Since the most active schedule was also the least toxic one by 2- to 10-fold, chrono-FFL was further intensified in three consecutive Phase II trials involving a total of 200 additional patients. Results suggest that both response rate and quality were further improved with such treatment intensification. Thus, chrono-FFL more than doubled the activity of chemotherapy against metastatic colorectal cancer in a multicentre European setting.(ABSTRACT TRUNCATED AT 250 WORDS)

Circadian rhythms and cancer chemotherapy

Experimental and clinical pertinent data regarding circadian rhythmicities are reviewed in (1) target tissues, i.e., healthy tissues (actively proliferating or not) and tumor tissues, (2) pharmacology of anticancer agents, (3) toxicity and tolerance of these agents and (4) antitumor activity of cancer chemotherapy. The basic concepts of chronotolerance and/or of chronoefficacy have brought new hopes for further amelioration in the management of cancer patients. Quite recent published Phase II and III clinical trials have demonstrated that new improvements on the therapeutic index have been achieved through ambulatory chronotherapy for various solid tumors.

Chronobiology. Implications for cancer chemotherapy

Experimental studies have documented that both the toxicity and the antitumor activity of many cancer drugs are time dependent. Early clinical trials have confirmed this observation for several drugs. The basic concepts of chronobiology and its application to pharmacology are reviewed. As an example, clinical trials of circadian fluoropyrimidine delivery are reviewed. Other clinical results are presented in table form. The mechanisms pertinent to the circadian time dependence of fluoropyrimidines are discussed.