Optimal circadian time of vinorelbine (V) combined with chronomodulated 5-FU in pretreated metastatic breast cancer patients. EORTC 05971 randomized multicenter study

2066

Background: Chronotherapy is an aim to increase efficacy/toxicity ratio. Objectives: to define the dosing least toxic time (DLTT) of V (30 mg/m2/d at D1 and D6), combined with chrono 5-FU (10 pm-10 am) (850 mg/m2 D2-D5) over 3 courses q3w. Methods: A logistic regression model (LRM) estimated the DLTT assuming a sinusoidal distribution over time (i.e. over the 8 different arms) of the toxicity rate observed in each arm. The associated 90% confidence limits (CL) has been obtained by bootstrap method. Results: 90 patients were recruited. Toxicity in 46 pts led to the V dosage reduction to 25 mg/m2/d. 40 and 43 pts were assigned the V30 and the V25 regimen. 12% pts went off for toxicity, 5% for PD, 1% for refusal, 1% for unrelated death. 224 cycles were analyzed . V and 5FU relative dose intensities were 79.4% and 78.2% in the V30 while 88.1% and 87.4% in the V25 pts. Over the 3 cycles, toxicity by cycle was: Grade (G) 3 and G4 leucopenia in 47% and 29%, G3 and G4 neutropenia in 12% and 77%. G3 febrile neutropenia in 34%. G2 thrombopenia and anemia in 4% each. Other G3 and G 4 toxicity were stomatitis (12%), alopecia (7%), and less than 5%: cardiovascular, lethargy, diarrhea, constipation, other gastrointestinal, infection, sensory, pulmonary. LRM could not demonstrate a DLTT for the neutropenia G3–4 incidence, the primary endpoint. However, based on the stratified by dose analysis, a 90% CI of less than 6 hours width was observed: - around 17H17 [14H04–20H03] for the incidence of leucopenia G3–4. - around 8H16 [06H04–10H39] for tolerability (dose reduction, dose delay or treatment interruption for toxicity reason). This suggests that treatment tolerability was influenced by other factors beside leucopenia nadir. No other 90% CI of less than 6 hours width could be observed for other toxicity endpoints. Conclusions: Using a novel time finding study design with ad hoc statistics, this first randomized multicenter study has determined a DLTT for Vinorelbine in 90 women with MBC. Additional studies are ongoing to further assess the relevance of this trial design method that could prove useful for improving the safety of anticancer drugs during their clinical development. Support Pierre Fabre Oncology, Ligue Bourguignonne contre le Cancer

No significant financial relationships to disclose.

Effective salvage therapy of liver-only colorectal cancer metastases with chronomodulated irinotecan-fluorouracil-oxaliplatin via hepatic artery infusion

3585

Background: Cell cycle and pharmacology genes are controlled by the molecular clock in normal liver but not in tumors (Filipski et al. JNCI 2005). As a result, circadian-based hepatic artery infusions of 3 main active drugs (ChronoHAI) could improve both tolerability and efficacy in patients (pts) with liver metastases from colorectal cancer. Methods: The therapeutic potential of 3-drug chronoHAI was evaluated in 28 heavily pretreated non hospitalized pts with metastatic colorectal cancer (MCC). They received 5-day (d) q21 d courses (c) with d1 irinotecan (160 mg/m2 from 2 to 8 am, peak at 5 am) and d2–5 oxaliplatin (20 mg/m2/d from 10 am to 10 pm, peak at 4 pm) and 5-fluorouracil (600 mg/m2/d from 10 pm to 10 am, peak at 4 am). 149 courses (c) were given (median, 5 ; 1–15) using a multichannel pump (Mélodie, Aguettant, F). Toxicity was assessed q21 d and response q3 c with CT scan. Results: Pt characteristics: prior chemotherapy lines 1/2/3/4+: 3/4/8/13 pts; WHO Performance Status 0/1/2/3 : 12/9/6/1 pts; median age: 63 years (32–73); liver only: 21 pts; liver and lung: 7 pts. Treatment was withdrawn for thrombosis (6 pts) and/or Grade (gr) 3 abdominal pain (3 pts). Grade 3–4 diarrhea and vomiting respectively occurred in 6 pts (21%) and 4 pts (14%) and were the main toxicities. Leucopenia, anemia and thrombocytopenia were respectively encountered in 5, 2 and 1 pt (< 18%). NCIC gr 3 sensory neuropathy occurred in 4 pts and alopecia in 3 pts. Of 25 pts with measurable lesions, disease progressed in 11 pts (exclusively outside the liver for 3 pts) and was controlled in 14 pts (56%), including 8 objective responses - 32% [95% C.L. 13.4 to 50.6]. Partial hepatectomy was performed in 3 pts with measurable disease (12%): R0 (2 PR) and R1 (1 SD). Median Progression free survival is 5 months [2.5 to 7.5] and median survival is 18.4 mo [10.5 to 26.3]. Five pts are alive at 2 to 51 mo. Conclusions: 3-drug chronoHAI is safe in heavily pretreated pts and achieves consistent activity against colorectal cancer liver metastases despite prior failure to oxaliplatin, irinotecan and fluorouracil. The addition of systemic molecular targeted therapy could be useful for preventing extra hepatic dissemination. Supported by ARTBC, Hôpital P. Brousse, Villejuif, France

No significant financial relationships to disclose.

Preclinical relevance of dosing time for the therapeutic index of gemcitabine-cisplatin

The relevance of gemcitabine timing for chronotherapeutic optimisation was investigated. Healthy mice received multiple doses of gemcitabine (120, 160 or 200 mg kg⁻¹ injection (inj)⁻¹) at one of six circadian times (3, 7, 11, 15, 19 or 23 h after light onset – HALO) on days 1, 4, 7 and 10 or a single dose of gemcitabine (400 mg kg⁻¹) at 11 or 23 HALO±cisplatin (5 mg kg⁻¹ at 1 min, 4 or 8 h later). Mice bearing Glasgow osteosarcoma received multiple doses of gemcitabine (200 mg kg⁻¹ inj⁻¹) at 11 or 23 HALO±cisplatin (5 mg kg⁻¹ inj⁻¹ at 1 min or 4 h later) on days of 10, 13, 16 and 19 following tumour inoculation. A circadian rhythm in body weight loss was statistically validated, with 1030 HALO corresponding to the least toxic time (95% CL, 0800 to 1300). Gemcitabine dosing produced least body weight loss and least neutropenia after injection at 11 vs 23 HALO, whether the drug was given alone or with cisplatin (P=0.001). Gemcitabine–cisplatin tolerability was improved by dosing gemcitabine at 11 HALO and CDDP at 15 HALO (P<0.001). The administration of this schedule to tumour-bearing mice increased median survival three-fold as compared to treatments where both drugs were given simultaneously at 11 or 23 HALO (P=0.02). The optimal schedule would correspond to the delivery of gemcitabine upon awakening and cisplatin near mid-activity in cancer patients.

[Algorithm of determination of circadian gene expression profiles analysed with DNA microarrays]

DNA microarrays allow to simultaneously determine the expression level of thousands of genes. A nycthemeral study must enable to conclude which ones show a circadian rhythm. Two aspects prove this to be quite difficult: firstly, what does "circadian" exactly mean and how to quantify this qualification, and secondly which genes pertain to this definition. Our method, derived from linear optimisation procedures, consists in determining a cost function, depending from magnitudes characterising the notion of circadian rhythm. Given number of genes present on the microarray are known to be expressed rhythmically; their time series are considered as reference series. We have further constructed random series having the same temporal structure as the circadian gene series. We then carried out an optimisation procedure to determine the weighting coefficients in order to obtain a cost function value which orders the time series as follows: the reference series are in the first rows and the random series have low scores. We have tested this method on over 6000 genes expressed in mouse liver. We obtained a circadian gene detection probability of 100% with a false positive rate inferior to 1%.

Chronobiologie et immunité

At all times, cycles have focused men's attention and fashioned his life. Today, thanks to genetic, one can find tracks of circadian rhythms programming until cell's DNA, and this in a very amazing and similar manner from amoebas to mammals. A particular rhythm interests the researcher in oncology: the circadian rhythm of melatonin. It stands at the junction of several domains: somatic, immune and psychic, through the many receptors found on leukocytes, through the links between this hormone production and the one of many cytokines but also with activity, life habits and "stress". On an other hand, antioxydant action of melatonin gives a serious argument concerning its possible role in cancer aetiology. As for them, studies on sleep confirm the large ubiquity of biological cycles, for instance thanks to the observation of the impact of particular genetic mutations on advance or delayed sleep syndrome. Because of the great diversity of cyclic phenomena, the study of chronobiology cannot be undertaken today without a wide interdisciplinary collaboration. During the 13th congress of the "Association Francaise de Chronobiologie Medicale", this study has been continued mainly in three different directions of research: fundamental, applied and transverse. Many original experimental results have been presented and new ways of multidisciplinary research specified. The important scientific fecundity of this very convivial annual congress never lacks to satisfy its participants: it continues to favour the onset of new projects, enabling to avoid major shelves thanks to the constructive criticism of each domain specialists.

Circadian rhythm entrainment with melatonin, melatonin receptor antagonist S22153 or their combination in mice exposed to constant light

The ability of daily melatonin and the melatonin receptor antagonist, S22153, to entrain circadian system function was investigated in mice with atypical melatonin rhythm. B6D2F(1) mice were first synchronized to a LD 12:12 for approximately 2 wk, then exposed to continuous light (LL) until study completion. After 10-18 days of LL exposure, mice received daily subcutaneous (s.c.) melatonin at a dose of 0.1, 1 or 10 mg/kg/day (exp. 1) or daily intraperitoneal (i.p.) S22153 (20 mg/kg/day) with or without melatonin (1 mg/kg/day, exp. 2) at subjective zeitgeber time (ZT) 10 for 19 days. Then all the mice were exposed to LL for another 10 days. Spectral analysis showed that initial LL lengthened the period of both rhythms by approximately 1.5 hr as compared with LD 12:12. No entrainment of either rhythm was found in controls. Conversely, daily melatonin-only, S22153-only or their combination set the temperature and activity periods to approximately 24 hr and produced a significant increase of the circadian amplitude of both rhythms as compared with controls. However, after treatment withdrawal, the dominant period lengthened to approximately 25.5 hr in mice receiving either melatonin or S22153. On the contrary, the period remained close to 24 hr for the 10 days following withdrawal of combined S22153 and melatonin. Such sustained pharmacological resetting of circadian function could display therapeutic potential against external resynchronization resulting from defective photoperiodic entrainment.

Effects of meal timing on tumor progression in mice

Meal timing can reset circadian clocks in peripheral tissues. We investigated the effects of such non-photic entrainment on tumor growth rate. Two experiments involved a total of 61 male B6D2F(1) mice synchronized with an alternation of 12 h of light (L) and 12 h of darkness (D) (LD12:12). Mice were randomly allocated to have access to food ad libitum, or restricted to 4 or 6 h during L or D. Rest-activity and body temperature, two circadian outputs, were monitored with an intra-peritoneal sensor. Glasgow osteosarcoma was inoculated into both flanks of each mouse ten days after meal timing onset. Before tumor inoculation, meal timing during D amplified the 24-h rhythms in rest-activity and body temperature with minimal phase alteration as compared to ad libitum feeding. Conversely, meal timing during L induced dominant 12-h or 8-h rhythmic components in activity, nearly doubled the 24-h amplitude of body temperature and shifted its acrophase (time of maximum) from approximately mid-D to approximately mid-L. Thirteen days after tumor inoculation, mean tumor weight (+/- SEM, mg) was 1503 +/- 150 in ad libitum mice, 1077 +/- 157 in mice fed during D and 577 +/- 139 in mice fed during L (ANOVA, p < 0.0001). Overall survival was prolonged in the mice fed during L (median, 17.5 days, d) as compared with those fed during D (14.5 d) or ad libitum (14 d) (Log Rank, p = 0.0035). The internal desynchronization produced by meal timing during L slowed down tumor progression, an effect possibly resulting from improved host-mediated tumor control and/or altered tumor circadian clocks.

Role of neoadjuvant chemotherapy in the treatment of multiple colorectal metastases to the liver

BACKGROUND

The role of neoadjuvant chemotherapy for patients with multiple (five or more) bilobar hepatic metastases irrespective of initial resectability is still under scrutiny. The purpose of this study was to compare the outcome of hepatectomy alone with that of hepatectomy after neoadjuvant chemotherapy for multiple bilobar hepatic metastases from colorectal cancer.

METHODS

Retrospective data were collected from 71 patients after hepatectomy for five or more bilobar liver tumours. The outcome of 48 patients treated by neoadjuvant chemotherapy followed by hepatectomy was compared with that of 23 patients treated by hepatectomy alone.

RESULTS

Patients who received neoadjuvant chemotherapy had better 3- and 5-year survival rates from the time of diagnosis than those who did not (67.0 and 38.9 versus 51.8 and 20.7 per cent respectively; P = 0.039), and required fewer extended hepatectomies (four segments or more) (39 of 48 versus 23 of 23; P = 0.027). Multivariate analysis showed neoadjuvant chemotherapy to be an independent predictor of survival.

CONCLUSION

In patients with bilateral multiple colorectal liver metastases, neoadjuvant chemotherapy before hepatectomy was associated with improved survival and enabled complete resection with fewer extended hepatectomies.

It is time for chronotherapy!

The EORTC Chronotherapy Group (CTG) stemmed from the International Organisation for Cancer Chronotherapy(IOCC) in 1996. The IOCC was the first to initiate large scale multicentre international chronotherapy trials, for the purpose of investigating the relevance of chronomodulated or timed administration of cancer therapy based on biological rhythms. Programmable pumps for cytotoxic chronodelivery and actigraph devices to monitor circadian rhythm alterations linked to cancer were also developed. The unique expertise of the IOCC with regard to cancer chronotherapy furthered its development within the EORTC. EORTC offers broad expertise in clinical cancer research and opportunities for scientific recognition, inter-group collaborations and translational research. Over the past 5 years, EORTC CTG has grown from 16 to 48 centres in 12 different countries. It is currently conducting seven multicentre chronotherapy trials, which test the relevance of adapting cancer treatment delivery to circadian rhythms. The group aims at developing multiple collaborations to establish a chronotherapy network involving institutions with expertise ranging from experimental chronobiology to new drug testing, disease-specific management and quality of life or survival issues.

Dihydropyrimidine dehydrogenase circadian rhythm in mouse liver: comparison between enzyme activity and gene expression

Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme of 5-fluorouracil (FU) catabolism. The relevance of the measurement of DPD activity for identifying DPD-deficient patients is lessened by circadian variability in DPD activity. Our purpose was to determine whether or not DPD mRNA is sustained by a circadian rhythm. Synchronised mice (male B6D2F1) were sacrificed at 3, 7, 11, 15, 19 or 23 Hours After Light Onset (HALO; eight mice per time-point). Liver DPD activity was determined by a radio-enzymatic assay and liver DPD expression by a reverse transcriptase-polymerase chain reaction (RT-PCR) enzyme-linked immunosorbent assay (ELISA) method. Mice synchronisation was controlled by leucocyte and neutrophil counts. Individual DPD activity ranged from 555 to 1575 pmol/min/mg prot; mean DPD activity was highest at 3 HALO (mean+/-standard error of the mean (S.E.M.); 1105+/-70) and lowest at 15 HALO (889+/-71). Individual liver DPD expression varied from 761 to 3481 units (DPD/beta actin ratio); the mean was lowest at 3 HALO (1406+/-112) and highest at 15 HALO (2067+/-214). Cosinor analysis indicated that respective double amplitudes of DPD activity and expression were 21 and 30% of the 24-h mean. The acrophases for activity and expression were 6:40 and 14:10 HALO, respectively, meaning that maximum activity occurred 16 h after the maximum observed expression. These results, revealing the existence of a circadian rhythm in DPD expression, should stimulate further studies to enhance our understanding of the molecular mechanisms involved in the circadian regulation of the DPD enzyme.

Circadian optimisation of irinotecan and oxaliplatin efficacy in mice with Glasgow osteosarcoma

The relevance of circadian rhythms in irinotecan and oxaliplatin tolerability was investigated with regard to antitumour activity. Mice bearing Glasgow osteosarcoma (GOS) received single agent irinotecan (50 or 60 mg kg(-1) per day) or oxaliplatin (4 or 5.25 mg kg(-1) per day) at one of six dosing times expressed in hours after light onset (3, 7, 11, 15, 19 or 23 hours after light onset). Irinotecan (50 mg kg(-1) per day) and oxaliplatin (4 or 5.25 mg kg(-1) per day) were given 1 min apart at 7 or 15 hours after light onset, or at their respective times of best tolerability (7 hours after light onset for irinotecan and 15 hours after light onset for oxaliplatin) or worst tolerability (15 hours after light onset for irinotecan and 7 hours after light onset for oxaliplatin). Tumour growth rate was nearly halved and per cent increase in estimated life span (% ILS) was - doubled in the mice receiving irinotecan at 7 hours after light onset as compared to 15 hours after light onset (P<0.05). Results of similar magnitude were obtained with oxaliplatin for both endpoints, yet with 7 hours after light onset corresponding to least efficacy and 15 hours after light onset to best efficacy (P<0.05). Irinotecan addition to oxaliplatin proved therapeutic benefit only if the schedule consisted of irinotecan administration at 7 hours after light onset and oxaliplatin delivery at 15 hours after light onset, i.e. when both drugs were given near their respective "best" circadian times. These would correspond to the middle of the night for irinotecan and the middle of the day for oxaliplatin in humans.

It's time for chronotherapy!

The EORTC Chronotherapy Group (CTG) stemmed from the International Organisation for Cancer Chronotherapy (IOCC) in 1996. The IOCC was first to initiate large scale multicentre international chronotherapy trials, for the purpose of investigating the relevance of chronomodulated or timed administration of cancer therapy based on biological rhythms. Programmable pumps for cytotoxic chronodelivery and actigraph devices to monitor circadian rhythm alterations linked to cancer were also developed. The unique expertise of the IOCC with regard to cancer chronotherapy furthered its development within the EORTC. The EORTC offers broad expertise in clinical cancer research and opportunities for scientific recognition, intergroup collaborations and translational research. Over the past 5 years, the EORTC CTG has grown from 16 to 48 centres in 12 different countries. It is currently conducting seven multicentre chronotherapy trials which test the relevance of adapting cancer treatment delivery to circadian rhythms. The group aims at developing multiple collaborations to establish a chronotherapy network involving institutions with expertise ranging from experimental chronobiology to new drug testing, disease-specific management and quality of life or survival issues.

Phase II trial of chronomodulated infusion of high-dose fluorouracil and l-folinic acid in previously untreated patients with metastatic colorectal cancer

PURPOSE

To study tolerability and efficacy of an intensified chronomodulated schedule of fluorouracil (5-FU) and l-folinic acid (l-FA) as first-line treatment of metastatic colorectal cancer, 5-FU was given near individually determined dose-limiting toxicity in a multicenter phase II trial.

PATIENTS AND METHODS

One hundred patients (68 men and 32 women, median age 62 years, World Health Organization performance status less-than-or-equal 2) with previously untreated and inoperable metastases received chronomodulated daily infusion of 5-FU/l-FA (from 10:00 PM to 10:00 AM with peak at 4:00 AM). 5-FU dose was escalated from 900 to 1,100 mg/m(2)/d with fixed dose of l-FA at 150 mg/m(2)/d for 4 days every 14 days.

RESULTS

5-FU dose escalation was achieved in 66% of the patients. Grade 3 to 4 toxicities mainly consisted of nausea or vomiting (14% of patients and 1.5% of courses), hand-foot syndrome (38% of patients and 8% of courses), mucositis (26% of patients and 4% of courses), and diarrhea (21% of patients and 2.3% of courses). Objective response rate (ORR) was 41% (95% confidence interval, 31.5% to 50.5%). Twenty patients underwent metastases surgery; among these, 12 had a complete resection. Median progression-free survival was 7 months. Median survival was 17 months; 28% of the patients were alive at 2 years and 18.6% at 3 years.

CONCLUSION

The ORR achieved with intensified chronomodulated delivery of 5-FU/l-FA was nearly twice as high as that earlier obtained by our cooperative group using less intensive 5-FU/FA chronotherapy.

Factors predicting efficacy of oxaliplatin in combination with 5-fluorouracil (5-FU) +/- folinic acid in a compassionate-use cohort of 481 5-FU-resistant advanced colorectal cancer patients

A statistical analysis was performed on the patient data collected from two compassionate-use programmes using oxaliplatin (Eloxatin(R)) + 5-fluorouracil (5-FU) +/- folinic acid (FA), to identify predictive factors for oxaliplatin-based salvage treatment in patients with 5-FU-resistant advanced colorectal cancer (ACRC). 481 5-FU-resistant ACRC patients, most with performance status < or = 2, > or = 3 involved sites, and > or = 2 prior lines of chemotherapy, received oxaliplatin + 5-FU +/- FA. Prognostic factors associated with overall response rate (ORR), time to progression (TTP) and overall survival (OS) were identified using univariate and multivariate logistic and/or Cox proportional hazards analyses. The ORR was 16% (95% CI: 13-20), the median TTP was 4.2 months (95% CI: 3.4-4.6), and the median OS was 9.6 months (95% CI: 8.6-10.6). The multivariate analysis indicated poor (> or = 2 WHO) performance status (PS), a large number of prior chemotherapy regimens (> or = 3), a low baseline haemoglobin level (< 10 g/dl), and a triweekly (vs biweekly) treatment administration schedule as significantly associated (P< 0.05) with a lower ORR. Sex (male), number of organs involved (> or =3) and alkaline phosphatase (AP) level (> or = 2 x the upper limit of normal) were associated (P< 0.05) with shorter TTP. Poor PS, a large number of organs involved, and elevated AP were independently and significantly correlated with shorter OS. Our analysis identified a relationship between efficacy results of oxaliplatin + 5-FU +/- FA treatment in 5-FU-resistant ACRC patients and baseline prognostic factors related to PS, extent of disease and number of prior regimens.

Circadian chronotherapy for human cancers

Cell physiology is regulated by a 24-hour clock, consisting of interconnected molecular loops, involving at least nine genes. The cellular clock is coordinated by the suprachiasmatic nucleus, a hypothalamic pacemaker which also helps the organism to adjust to environmental cycles. This circadian organisation brings about predictable changes in the body's tolerance and tumour responsiveness to anticancer agents, and possibly also for cancer promotion or growth. The clinical relevance of the chronotherapy principle, ie treatment regimens based upon circadian rhythms, has been demonstrated in randomised, multicentre trials. Chronotherapeutic schedules have been used to document the safety and activity of oxaliplatin against metastatic colorectal cancer and have formed the basis for a new approach to the medicosurgical management of this disease, which achieved unprecedented long-term survival. The chronotherapy concept offers further promise for improving current cancer-treatment options, as well as for optimising the development of new anticancer or supportive agents.

Experimental chronotherapy of mouse mammary adenocarcinoma MA13/C with docetaxel and doxorubicin as single agents and in combination

The therapeutic index of docetaxel, doxorubicin and their combination may be improved by an adequate selection of the circadian time of administration. The present study constitutes a prerequisite to testing the clinical relevance of chronotherapy in human breast cancer. Three experiments were performed in C3H/HeN mice. Each treatment modality was administered i.v. once a week for 3 weeks at one of six circadian stages, during the light span, when the mice were resting: 3, 7, and 11 h after light onset (HALO), or during darkness, when the mice were active: 15, 19, and 23 HALO. The circadian time dependency of single agent tolerability was investigated in healthy mice using four dose levels for docetaxel (38.8, 23.3, 14, and 8.4 mg/kg/injection) and for doxorubicin (13.8, 8.3, 5 and 3 mg/kg/injection; experiment 1). The circadian time dependency of each single agent efficacy was studied in MA13/C-bearing mice, using two dose levels of docetaxel (38.8 or 23.3 mg/kg/injection) or doxorubicin (8.3 or 5 mg/kg/injection; experiment 2). The toxicity and the efficacy of the simultaneous docetaxel-doxorubicin combination were assessed as a function of dosing time in experiment 3. Two combinations were tested (A, 16.3 mg/kg/injection of docetaxel and 2.5 mg/kg/injection of doxorubicin; and B, 11.6 and 3.5 mg/kg/injection, respectively) at each of the above six circadian times. Mortality, body weight change, and tumor size were recorded for 60-70 days in each experiment. Single agent docetaxel or doxorubicin was significantly best tolerated near the middle of the rest span (7 HALO) and most toxic in the middle of the activity phase (19 HALO). Docetaxel or doxorubicin as a single drug were also most effective at 7 HALO, irrespective of dose. Treatment at 7 HALO produced highest rates of complete tumor inhibition (81% versus 11% at 3 HALO for docetaxel, p from chi2 <0.001, and 69% versus 44% at 11 HALO for doxorubicin, not significant) and highest day 60 survival rate (100% versus 28% at 3 HALO for docetaxel, p from chi2 <0.001 and 89% versus 69% at 15 HALO for doxorubicin, not significant). Docetaxel-doxorubicin combinations were most effective following dosing in the beginning of the rest span or short after the onset of the activity span, with regard to the rates of both complete tumor inhibitions (45% at 3 HALO versus 15% at 19 HALO) and day 70 survival rates (85% and 80% at 3 and 7 HALO respectively, versus 20% at 19 HALO). The efficacy of single agent docetaxel or doxorubicin and that of their combination varied largely as a function of circadian dosing time. Single agent docetaxel at 7 HALO was the best treatment option in this model with regard to both tolerability and efficacy. This timing may correspond to the middle of the night in cancer patients.

Chronotherapy of colorectal cancer metastases

Chronotherapy has consisted in the adaptation of chemotherapeutic drug delivery to circadian (approximately 24-hour) rhythms. This can be achieved in fully ambulatory patients using multichannel programmable pumps. Up to approximately 1500 patients with metastatic colorectal cancer have been registered in one of 15 trials testing the relevance of this treatment method with 5-fluorouracil +/- leucovorin +/- oxaliplatin. Chronotherapy was shown as significantly less toxic and more effective than constant rate infusion in 2 consecutive multicenter trials. High efficacy and good tolerability permitted secondary surgical resection of previously inoperable metastases, with apparent survival improvement (3-year survival > or = 20%) and cures in some patients. This strategy is currently undergoing further testing within the European Organization for Research and Treatment of Cancer. Nevertheless, combining chronotherapy with surgery of colorectal cancer metastases can be readily offered to patients as a safer therapeutic option for optimizing outcome.

Circadian variation in O6-alkylguanine-DNA alkyltransferase activity in circulating blood mononuclear cells of healthy human subjects

Cytotoxic agents such as chloroethylnitrosoureas (CENUs) mostly alkylate DNA on the O6-guanine position. This highly mutagenic lesion can be repaired by O6-alkylguanine-DNA alkyltransferase (AGT), which removes the alkyl group by accepting it to the cysteine residue of its active site. AGT activity displayed a circadian rhythm in mouse liver, coincident with that of CENU tolerability. We investigated whether AGT activity displayed a circadian rhythm in human circulating mononuclear cells (MNCs). The study was performed in 12 healthy volunteers aged 19 to 31 years. Circadian synchronization was verified with rest/activity cycle as assessed with wrist actigraphy and plasma cortisol and melatonin rhythms. Subjects were hospitalized for 24 hr and blood samples were obtained at 08:00, 12:00, 16:00, 20:00, 22:00, 00:00, 02:00, 04:00 and 08:00 overnight. MNCs were isolated on Ficoll immediately after blood sampling and frozen at -196 degrees C until AGT activity determination by HPLC. Mean AGT activity (+/- SEM) varied from 821 +/- 67 fmol/mg of total proteins at noon (trough), up to 1,055 +/- 80 fmol/mg at midnight (peak), i.e., by approximately 30%. A circadian rhythm was statistically validated with both analysis of variance (p < 0.009) and cosinor (p < 0.02) for AGT activity in MNCs (acrophase +/- SD at 00:30 +/- 210 min) as well as for MNC circulating count and for plasma cortisol and melatonin concentrations. Despite individual variations in the extent of AGT activity rhythm (more or less pronounced according to subject), AGT activity displayed a circadian rhythm in human MNCs of our healthy study group subjects. The results warrant to further investigate AGT rhythmicity both in circulating MNCs and in target tissues of cancer patients, as a prerequisite for clinical testing of chronotherapy with alkylating agents.