Factors predicting for efficacy of oxaliplatin in combination with 5-fluorouracil (5-FU)+/-folinic acid (FA) in a compassionate-use cohort of 370 5-FU-resistant advanced colorectal cancer (CRC) patients

Univariate and multivariate analyses were performed on data from 370 5-fluorouracil (5-FU)-resistant advanced colorectal cancer patients treated with oxaliplatin (Eloxatin)/5-FU+/-folinic acid (FA) to identify prognostic factors for oxaliplatin-based treatment. The response rate was 14.6% (95% confidence interval (CI): 11.0-18.2%), median time to progression was 4.3 months (95% CI: 3.9-4.7), and median overall survival 9.7 months (95% CI: 8.5-10.8). Multivariate analysis indicated < 2 prior chemotherapy regimens, bi-weekly treatment administration schedule (versus tri-weekly) and continuous chronomodulated delivery (CCM) as significantly associated (P < 0.05) with a higher overall response rate. Performance status (PS) < 2, having only one involved organ, biweekly schedule and CCM were associated (P < 0.05) with a longer time to progression. Good PS, one involved organ, low alkaline phosphatase (AP) serum levels, bi-weekly schedule and CCM were significantly correlated with longer overall survival, while confirming the efficacy of oxaliplatin/5-FU+/-FA in this indication.

Marked 24-h rest/activity rhythms are associated with better quality of life, better response, and longer survival in patients with metastatic colorectal cancer and good performance status

The rest/activity circadian cycle has been used as a reference for chemotherapy administration at specific times to improve tolerability and efficacy. Because cancer processes may be associated with alterations of circadian rhythms, the rest/activity cycle was monitored noninvasively to assess its relationship with tumor response, survival, and quality of life in 200 patients with metastatic colorectal cancer. Patients wore an actigraph, a wristwatch that records the number of accelerations per minute, for 3 days before receiving chronomodulated chemotherapy. The circadian rhythms in activity were estimated by two robust parameters: the autocorrelation coefficient at 24 h (r24), and the dichotomy index (I<O) for comparing amounts of activity when in bed and out of bed. Accurate data for inclusion, quality of life, response, and survival were available for 192 patients. Survival at 2 years was 5-fold higher (P = 10(-4)) in patients with marked activity rhythm (I<O in upper quartile) than in those with rhythm alteration (I<O in lower quartile). These results were supported by the multivariate Cox analysis. Multivariate regression analysis showed that circadian rhythms in activity (I<O; P = 3 x 10(-4)) and in WBCs (P = 0.03) as well as performance status (P = 0.02) were jointly prognostic of response. Patients with marked rest/activity rhythms also had better quality of life and reported significantly less fatigue. The individual rest/activity cycle provides a novel independent prognostic factor for cancer patients' survival and tumor response as well as a quantitative indicator for quality of life.

Overcoming resistance to chronomodulated 5-fluorouracil and folinic acid by the addition of chronomodulated oxaliplatin in advanced colorectal cancer patients

The addition of oxaliplatin (L-OHP) to a 5-fluorouracil (5-FU)/ leucovorin (FA) regimen was retrospectively evaluated in 35 consecutive advanced colorectal cancer patients after progression of disease. L-OHP, 25 mg/m2/day, was infused from 10.00-22.00 with a peak flow at 16.00 while 5-FU, 700 mg/m2/day and FA, 150 mg/m2/day of the I-form or 300 mg/m2/day of the racemic form, from 22.00 to 10.00 with a nocturnal peak at 4.00, for 5 days every 3 weeks in 24 patients and for 4 days every 2 weeks in the other 11. Diarrhea and sensitive neuropathy were the most relevant types of toxicity (17% of patients). An objective response was achieved in 8/35 patients (23%) [95% CL 9-37], stabilization in 15 patients (43%) which included five minor responses, and progression in 12. There was no relevant difference in quality of life assessed with the EORTC QLQ C30+3 questionnaire before and after treatment. Median duration of response and median progression-free survival were 6 months; median overall survival was 11 months. This retrospective study showed that it is possible to reverse resistance to chronomodulated 5-FU by adding chronomodulated L-OHP to the previous regimen; comparison with different schedules of this combination should be performed in order to identify the best tolerated and active regimen as second-line treatment of advanced colorectal cancer.

Therapeutic implications of circadian rhythms in cancer patients

Drug absorption, transport, metabolism and/or elimination usually show 24 h changes in both laboratory rodents and human beings. These variations in target cell exposure to drugs, as well as the rhythms which modulate cellular detoxification functions, account for the chronopharmacology of most medications, including anticancer agents, and have warranted the exploration of the relevance of the chronotherapy principle. Most of the cellular detoxication rhythms appear to be coupled to the rest-activity cycle, both in nocturnally active rodents and in diurnally active healthy subjects as well as in cancer patients. For instance, a 24 h rhythm was found in the activity of dehydropyrimidine dehydrogenase (DPD), both in rodent liver and in human circulating mononuclear cells, with a maximum located in the early rest span in either species. This cellular enzyme catabolizes 5-fluorouracil (5-FU), hence protects normal cells against damage produced by this widely used antimetabolite drug. Although DPD amplitude was nearly threefold in rodent liver and 40% in human lymphocytes, the adaptation of 5-FU administration to this rhythm largely improved tolerability both in rodents and in patients. The results thus support the coupling of the DPD rhythm and other chronopharmacology mechanisms to the average rest-activity cycle across species. The clinical relevance of such group chronotherapy has been further validated in Phase I, II and III clinical trials involving nearly 1500 patients. Multicentre randomized clinical trials have demonstrated that chronotherapy was both better tolerated and more effective than constant rate infusion in patients with metastatic colorectal cancer. Nevertheless 24 h rhythms in plasma cortisol or rest-activity could be altered in nearly 30% of cancer patients. Results from a prospective study performed in 200 patients with metastatic colorectal cancer indicated that poor circadian coordination constitutes an independent prognostic factor of both treatment tolerability and efficacy. Novel chronotherapeutic approaches targeted at circadian system coordination should then be devised in these patients.

Relationship of atypical melatonin rhythm with two circadian clock outputs in B6D2F(1) mice

Circadian rhythms in body temperature, locomotor activity, and the circadian changes of plasma and pineal melatonin content were investigated in B6D2F(1) mice synchronized by 12 h of light and 12 h of darkness. During 8 wk continuous recording, activity and temperature displayed a marked stable and reproducible circadian rhythm, with both peaks occurring near the middle of darkness. Both 24- and 12-h rhythmic components were also significantly detected. Mean plasma melatonin concentration rose steadily during the light span and reached a maximum (30.6 +/- 10.0 pg/ml) at 11 h after light onset (HALO), then gradually decreased after the onset of darkness to a nadir (4.7 +/- 0.4 pg/ml) at 20 HALO. Mean pineal content followed a pattern parallel to that of plasma concentration (peak at 11 HALO: 17.7 +/- 1.0 pg/gland; trough at 17 HALO: 4.7 +/- 1.0 pg/gland). In addition, a second sharp peak was observed at 21 HALO (20.2 +/- 3.5 pg/gland). Plasma and pineal contents displayed large and statistically significant circadian changes, with a composite rhythm of period (24 + 12 h). This mouse model has predominant production and secretion of melatonin during the day. This possibly contributes to a similar coupling between chronopharmacology mechanisms and the rest-activity cycle in these mice and in human subjects.

Dramatic tumor response of bulky liver metastases following treatment with CPT-11 and a chronomodulated 4-day infusion of 5-fluorouracil, folinic acid and oxaliplatin every 2 weeks in a colorectal cancer patient

Three active antitumor agents, i.e. 5-fluorouracil (5-FU), oxaliplatin and CPT-11, are available for the treatment of advanced colorectal cancer (CRC) patients and have been successfully combined in two-drug regimens. Hence, CRC has become a chemosensitive disease, but the optimal combination of these agents in first-line treatment remains to be determined. We report the first case of the combination of CPT-11 with oxaliplatin, 5-FU and folinic acid (FA) as first-line chemotherapy for a patient with a pre-occlusive sigmoid adenocarcinoma and synchronous bulky liver metastases. CPT-11 was given at 125 mg/m2, prior to the start of a chronomodulated 4-day infusion of oxaliplatin 25 mg/m2/day, 5-FU 800 mg/m2/day and FA 300 mg/m2/day repeated every 2 weeks. The doses could be escalated to 150 mg/m2 for CPT-11 and 900 mg/m2/day for 5-FU. After six cycles of chemotherapy 70% reduction in tumor size was documented in the liver. The primary tumor was no longer detectable by barium enema. The toxicity included three episodes of grade 4 neutropenic fever, and two episodes of severe diarrhea and vomiting with dehydration. A cumulative grade 2 neurosensory toxicity was observed after six cycles. Following surgery of the primary tumor, because of the major hepatic tumor response and of the absence of extra-hepatic metastases, the patient might be registered for a liver transplantation program. This first report of combining the three active agents in CRC every 2 weeks led to a high dose intensity of each agent and was associated with a dramatic tumor response of a very advanced disease in a patient with already altered performance status. The antitumor activity in this patient suggests that a three-drug intensified regimen might be feasible and active. A prospective study appears warranted to further examine the efficacy and toxicity of this therapeutic approach, and to determine whether it may increase the fraction of advanced CRC patients becoming resectable. This aggressive chemotherapy program may contribute to a re-examination of the usefulness of liver transplantation in patients with metastatic CRC confined to the liver.

Phase III multicenter randomized trial of oxaliplatin added to chronomodulated fluorouracil-leucovorin as first-line treatment of metastatic colorectal cancer

PURPOSE

To study how adding oxaliplatin (l-OHP) to chronomodulated fluorouracil (5-FU)-leucovorin (LV) affected the objective response rate, as first-line treatment of metastatic colorectal cancer.

PATIENTS AND METHODS

Two hundred patients from 15 institutions in four countries were randomly assigned to receive a 5-day course of chronomodulated 5-FU and LV (700 and 300 mg/m(2)/d, respectively; peak delivery rate at 0400 hours) with or without l-OHP on the first day of each course (125 mg/m(2), as a 6-hour infusion). Each course was repeated every 21 days. Response was assessed by extramural review of computed tomography scans.

RESULTS

Grade 3 to 4 toxicity from 5-FU-LV occurred in </= 5% of the patients (</= 1% of the courses). Grade 3 to 4 diarrhea occurred in 43% of the patients given l-OHP (10% of the courses), and less than 2% of the patients had severe hematotoxicity. Thirteen percent of the patients had moderate functional impairment from peripheral sensory neuropathy. Sixteen percent of the patients receiving 5-FU-LV had an objective response (95% confidence interval [CI], 9% to 24%), compared with 53% of those receiving additional l-OHP (95% CI, 42% to 63%) (P <. 001). The median progression-free survival time was 6.1 months with 5-FU-LV (range, 4.1 to 7.4 months) and 8.7 months (7.4 to 9.2 months) with l-OHP and 5-FU-LV (P =.048). Median survival times were 19.9 and 19.4 months, respectively.

CONCLUSION

By chronomodulating 5-FU-LV, we were able to add l-OHP without compromising dose-intensities. l-OHP significantly improved the antitumor efficacy of this regimen.

Oxaliplatin: pharmacokinetics and chronopharmacological aspects

Oxaliplatin is the first clinically available diaminocyclohexane platinum coordination complex. The drug is non-cross-resistant with cisplatin or carboplatin and is one of the few active drugs against human colorectal cancer. Its cytotoxicity is synergistic with fluorouracil and folinic acid (leucovorin), the reference treatment for this disease. The main cumulative dose-limiting toxicity of oxaliplatin is peripheral sensory neuropathy. The drug can also produce diarrhoea, vomiting and haematological suppression. Unlike cisplatin, no renal failure or peripheral motor neuropathy have been reported and the sensory neuropathy is partly reversible. Unlike carboplatin, oxaliplatin produces only mild to moderate haematological toxicity. Oxaliplatin undergoes biotransformation into aquated forms in the blood, where 3 species can be found: total platinum, ultrafilterable or 'free' platinum and erythrocyte platinum. Flameless atomic absorption (FAAS) is used for assaying platinum concentration in various tissues. Inductively-coupled plasma mass spectrometry (ICP-MS), with a >10-fold lower sensitivity threshold than FAAS, was also used for the determination of oxaliplatin pharmacokinetics. The pharmacokinetics of oxaliplatin are described by a 3-compartment model. The drug rapidly crosses the cellular membrane as a result of its lipophilicity. Hence, at the end of a 2-hour infusion, approximately 40% of the blood platinum is found in erythrocytes. The distribution half-life of ultrafiltrated plasma platinum ranges from 10 to 25 minutes and its terminal elimination half-life is 26 hours (determined with FAAS) or 270 hours (ICP-MS). The elimination half-life of erythrocytic platinum is 12 to 50 days, close to that of erythrocytes. 30 to 50% of the platinum is recovered in the urine within 2 to 5 days, with renal clearance accounting for half of the total clearance of ultrafiltrated platinum. The total clearance of this species is correlated with the glomerular filtration rate. No pharmacokinetic-pharmacodynamic relationship has been established for oxaliplatin. Pharmacokinetic alterations produced by fluorouracil + folinic acid or irinotecan were minimal if any. The prolonged stability of oxaliplatin makes it suitable for continuous infusions over 4 to 5 days, with a delivery rate which can be either constant or chronomodulated (peak rate at 1600h), using programmable ambulatory pumps. Chronomodulation significantly reduces toxicity and improves antitumour activity as compared with constant rate infusion. These differences in pharmacodynamic properties were paralleled by differences in plasma concentration time courses. The different drug concentration profiles achieved with different infusional modalities may be useful tools for understanding the relationship between the pharmacokinetics and pharmacodynamics of oxaliplatin and may lead to further optimisation of its administration schedule and its combination with other drugs.

Cancer chronotherapy

The cytotoxicity of more than thirty anticancer drugs varies by more than 50% as a function of dosing time along the 24-h time-scale in laboratory animals. Mechanisms involve circadian changes in cellular metabolism and proliferation processes, as well as drug pharmacokinetics. Moreover, the administration of chemotherapy at the least toxic time usually achieves best antitumour efficacy in experimental tumour models. Here we review experiences in utilising these phenomena in the optimization of cancer chemotherapy in the clinic. Chronotherapy has been administered to 1500 patients with metastatic colorectal cancer using 5-fluorouracil and leucovorin with or without oxaliplatin. Sinusoidal chronomodulated delivery of 2- or 3-drug chemotherapy was performed in the patient's home or during usual activities, with a computer-programmed multi-reservoir pump. Courses lasted 4-5 days and were repeated every 14-21 days. Three-drug chronotherapy proved largely superior to flat infusion with respect to both tolerability and antitumour efficacy. The better tolerability of chronotherapy further allowed an increment of both 5-fluorouracil and oxaliplatin doses, which in turn further improved objective tumour response rate to 66%. This enabled surgical removal of previously inoperable metastases and the achievement of > 20% survival at three years. Second generation programmable-in-time pumps have simplified chronotherapy administration and decreased its costs. A broad use of fully ambulatory chronotherapy requires thorough definitions of drug stability, and compatibility with pump reservoirs and other medications.

The tumor promoting effect of constant light exposure on diethylnitrosamine-induced hepatocarcinogenesis in rats

The hypothesis that light-induced circadian clock suppression exerts a promoting effect on liver carcinogenesis was investigated in rats. Sixty-five male Wistar rats were given diethylnitrosamine (DEN, 10 mg/kg/day p.o.) for 6 weeks and were randomized into 3 groups. Rats from group 1 (N=20) received DEN only. Rats from group 2 (N=22) also received phenobarbital (pheno, 30 mg/rat/day p.o.) for 4 weeks as a promoting agent and rats from group 3 (N=23) were exposed to continuous light. Three months after starting DEN treatment, urinary 6-sulfatoxymelatonin (alphaMT6s) excretion, a marker of circadian clock function, had lost its circadian rhythmicity in the LL group, with a 4-fold lower 24 h mean than that found in the LDpheno and LD groups (8.0 +/- 3.2 ng/ml, 33.6 +/- 3.1 ng/ml and 34.3 +/- 2.4 ng/ml respectively; p from ANOVA <0.001). Laparotomy was then performed. The proportion of rats with macroscopic nodules on liver surface was 72% (LD group), 89% (LDpheno group) and 95% (LL group) (p from chi2 = 0.1). Nodules were more numerous and larger both in the LL group and in the LDpheno one as compared to the LD group (p from chi2 <0.05). All the rats died with hepatocellular carcinomas, with a median survival of 5 months, similar in all 3 groups. Light-induced circadian clock suppression exerted a promoting effect similar to that caused by phenobarbital in this model, yet through different effects on circadian system function.

A multicenter evaluation of intensified, ambulatory, chronomodulated chemotherapy with oxaliplatin, 5-fluorouracil, and leucovorin as initial treatment of patients with metastatic colorectal carcinoma. International Organization for Cancer Chronotherapy

BACKGROUND

The combination of 5-fluorouracil (5-FU), leucovorin (LV), and oxaliplatin (I-OHP) was shown to be both more active against metastatic colorectal carcinoma and better tolerated if the drug delivery rate was chronomodulated according to circadian rhythms rather than constant. This allowed the authors to intensify the three-drug chronotherapy regimen and to assess its activity as the initial treatment of metastatic colorectal carcinoma patients in ten centers from four countries.

METHODS

Patients with previously untreated and inoperable measurable metastases from colorectal carcinoma received a daily administration of chronomodulated 5-FU (700 mg/m2/day, peak delivery rate at 04:00 hours), LV (300 mg/m2/day, peak delivery rate at 04:00 hours), and 1-OHP (25 mg/m2/day, peak delivery rate at 16:00 hours) for 4 days every 14 days. Intrapatient escalation of 5-FU dose was performed if toxicity was less than World Health Organization (WHO) Grade 2.

RESULTS

Of 90 enrolled patients, 35 had a WHO performance status of 1 or 2; 49 had metastases in > or = 2 organs. The liver was involved in 79 patients, 30 of whom had clinical hepatomegaly. The main dose-limiting toxicities were WHO modified Grade 3 or 4 diarrhea (41% of patients, 8.2% of courses), stomatitis (30% of patients, 5.1% of courses), and Grade 2 cumulative peripheral sensory neuropathy (19% of patients after 12 courses). Two patients died with severe gastrointestinal toxicity. Using the intent-to-treat method, the overall objective response rate was 66% (95% confidence limits, 56-76%). Surgical removal of previously inoperable metastases was successful in 31 patients (34%). Histologic necrosis of metastases was >90% in 7 patients and complete in 1 patient. The median progression free survival and survival durations were 8.4 months (range, 5.9-10.9 months) and 18.5 months (range, 13.2-23.8 months), respectively, with 38% of the patients alive at 2 years of follow-up.

CONCLUSIONS

The objective response rate appeared to be approximately 3-fold as high as that achieved with current 5-FU-based regimens and translated into an approximately 50% increase in median survival. The hypothesis that this intensified, ambulatory, chronotherapy regimen can increase survival currently is being investigated in a multicenter randomized study conducted by the European Organization for Research and Treatment of Cancer Chronotherapy Study Group.

Long-term survival of patients with unresectable colorectal cancer liver metastases following infusional chemotherapy with 5-fluorouracil, leucovorin, oxaliplatin and surgery

CONTEXT

Long-term survival of patients with metastatic colorectal cancer has been achieved only in patients who underwent complete resection of metastases. Such surgery could be performed in a greater proportion of patients if effective chemotherapy could downstage previously unresectable metastases. This approach has been limited by the low tumor response rate achieved with conventional chemotherapy.

OBJECTIVE

We studied the outcome of patients with initially unresectable liver metastases from colorectal cancer treated with a three-drug chemotherapy regimen followed by liver metastases surgery whenever possible.

PATIENTS AND METHODS

From March 1988 to June 1994, 151 patients with colorectal liver metastases were considered initially unresectable because of large tumor size (> 5 cm), multinodular (> 4) or ill-located metastases. All patients received fully ambulatory chemotherapy with 5-fluorouracil, leucovorin and oxaliplatin (chronotherapy in 83% of them). They were periodically reassessed for surgery by a joint medico-surgical team.

RESULTS

In 151 patients, the size of liver metastases decreased by > 50% in 89 patients (59%) and median overall survival was 24 months (95% confidence interval (95% CI): 19-28 months), with 28% surviving at five years (20%-35%). Surgery with curative intent was attempted in 77 patients (51%), complete resection of liver metastases was achieved in 58 patients (38%). The median survival of the 77 operated patients was 48 months (25-71), with a five-year survival rate of 50% (38-61).

CONCLUSION

This new strategy of combining effective chemotherapy with surgery apparently altered the natural history of unresectable colorectal cancer metastases.

Chronopharmacologic aspects of continuous AcSDKP infusion in mice

Inconsistent results characterized N-acetyl-Ser-Asp-Lys-Pro (AcSDKP or Goralatide) effects upon hematologic proliferation, possibly because its circadian organization had been overlooked. We investigated the circadian changes in AcSDKP disposition in plasma and in bone marrow during continuous infusion and AcSDKP effects upon the circadian rhythms in bone marrow granulomonocytic precursors (CFU-GM) and circulating blood cell counts. One hundred ninety-six male B6D2F1 mice received a constant infusion of AcSDKP (24 microg/ day) or 0.9% NaCl for 7 days, using an osmotic minipump. All mice were synchronized with an alternation of 12 hours of light and 12 hours of darkness for 3 weeks prior to study. Mice were sacrificed on the fifth or seventh infusional day at 3, 9, 15, or 21 hours after light onset (HALO) in order to assess plasma and bone marrow AcSDKP concentrations, CFU-GM, and/or circulating blood cell counts. In control mice, plasma and bone marrow AcSDKP concentrations displayed a circadian rhythm with a maximum level during the dark span, at 21 and 15 HALO respectively, while CFU-GM, leukocyte, lymphocyte, and monocyte counts peaked during early light. Continuous AcSDKP infusion increased fivefold mean plasma AcSDKP level at 3 or 9 HALO, thus inverted its physiologic rhythm and suppressed the CFU-GM peak that normally occurs at these times. This inhibition however, was indirect, because the rhythms in bone marrow AcSDKP concentration were similar with or without AcSDKP infusion. Conversely, mean leukocyte and lymphocyte counts were significantly reduced with AcSDKP infusion, while their circadian rhythms remained unaffected and were amplified. The results indicate that AcSDKP pharmacology displays circadian rhythmicity and warrant the exploration of chronopharmacologic schedules of AcSDKP delivery for further protecting bone marrow against chemotherapy insults.

Docetaxel chronopharmacology in mice

Docetaxel tolerance and antitumor efficacy could be enhanced if drug administration was adapted to circadian rhythms. This hypothesis was investigated in seven experiments involving a total of 626 male B6D2F1 mice, synchronized with an alternation of 12 h of light and 12 h of darkness (12:12), after i.v. administration of docetaxel. In experiment (Exp) 1, the drug was given once a week (wk) for 6 wks (20 mg/kg/wk) or for 5 wks (30 mg/kg/wk) at one of six circadian times, during light when mice were resting [3, 7, or 11 hours after light onset (HALO)], or during darkness, when mice were active (15, 19, or 23 HALO). Endpoints were survival and body weight change. In Exp 2 and 3, docetaxel (30 mg/kg/wk) was administered twice, 1 wk apart, at one of four circadian stages (7, 11, 19, or 23 HALO). Endpoints were hematological and intestinal toxicities. In Exp 4, circadian changes in cell cycle phase distribution and BCL-2 immunofluorescence were investigated in bone marrow as possible mechanisms of docetaxel tolerability rhythm. In Exp 5 to 7, docetaxel was administered to mice bearing measurable P03 pancreatic adenocarcinoma (270-370 mg), with tumor weight and survival as endpoints. Mice from Exp 5 and 6 received a weekly schedule of docetaxel at one of six circadian stages (20 or 30 mg/kg/wk at 3, 7, 11, 15, 19, or 23 HALO). In Exp 7, docetaxel (30 mg/kg) was given every 2 days (day 1, 3, 5 schedule) at 7, 11, 19, or 23 HALO. Docetaxel dosing in the second half of darkness (19 or 23 HALO) resulted in significantly worse toxicity than its administration during the light span (3, 7, or 11 HALO). The survival rate ranged from 56.3% in the mice treated at 23 HALO to 93.8 or 87.5% in those injected at 3 or 11 HALO, respectively (Exp 1, P < 0.01). Granulocytopenia at nadir was -49 +/- 14% at 7 HALO compared with -84 +/- 3% at 19 HALO (Exp 2 and 3, P < 0.029), and severe jejunal mucosa necrosis occurred in 5 of 8 mice treated at 23 HALO as opposed to 2 of 18 receiving docetaxel at 7, 11, or 19 HALO (Exp 2 and 3, P < 0.02). The time of least docetaxel toxicity corresponded to the circadian nadir in S or G2-M phase and to the circadian maximum in BCL-2 immunofluorescence in bone marrow. Docetaxel increased the median survival of tumor-bearing mice in a dose-dependent manner (controls: 24 days; 20 mg/kg weekly, 33 days; 30 mg/kg weekly or day 1, 3, 5 schedule, 44 or 46 days, respectively; Exp 5-7). Survival curves of treated mice differed significantly according to dosing time for each dose and schedule (P from log rank <0.003 to P < 0.03). In Exp 5 and 6, the percentage of increase in life span was largest if docetaxel was administered weekly at 7 HALO (20 mg/kg, 220%; 30 mg/kg, 372%) and lowest after docetaxel dosing at 19 HALO (80% with 20 mg/kg) or at 15 HALO (78% with 30 mg/kg). In Exp 7, (day 1, 3, 5 schedule), docetaxel was most active at 11 HALO (percentage increase in life span, 390%) and least active at 23 HALO (210%). Docetaxel tolerability and antitumor efficacy were simultaneously enhanced by drug dosing in the light span, when mice were resting. Mechanisms underlying the tolerability rhythm likely involved the circadian organization of cell cycle regulation. Docetaxel therapeutic index may be improved with an administration at night in cancer patients, when fewest bone marrow cells are in S or G2-M phase.

Modulation of nonprotein sulphydryl compounds rhythm with buthionine sulphoximine: relationship with oxaliplatin toxicity in mice

The relationship between the rhythm in tissue nonprotein sulphydryl groups (NPSH) and that in 1,2-diamine (trans-I)-cyclohexane oxalatoplatinum (1-OHP) toxicity was investigated in a total of 266 male B6D2F1 mice, using buthionine sulphoximine (BSO), an inhibitor of gamma-glutamylcysteine synthetase. Mice were synchronized with an alternation of 12 h light (L) and 12 h darkness (D; LD 12:12), and circadian time was expressed in hours after light onset (HALO). NPSH was measured in liver, jejunum and bone marrow at 0, 8 and 16 HALO. Dosing 1-OHP at these times achieved intermediate. high or low toxicity respectively. The physiological circadian rhythm in NPSH content was statistically significant in all tissues studied, with a maximum at the transition from D to L (0 HALO). BSO administration (450 mg/kg i.p., 4 h before sampling) induced a large depletion in liver and jejunum NPSH at their physiological peak (0 HALO), but exerted no significant effect at their trough (8 HALO). As a result, 24 h rhythm was suppressed in liver and jejunum, but remained similar to the physiological one in bone marrow. BSO enhanced 1-OHP-induced mortality and jejunal toxicity, but exerted no significant effect upon bone marrow toxicity. Despite these differences, 1-OHP remained least toxic at 16 HALO, near the middle of the dark span, which corresponds to maximum activity in the circadian rest/activity cycle. Our results show that mean NPSH levels in liver seem to account for the mean level of 1-OHP toxicity, while jejunal NPSH rhythm plays an important role in the intestinal toxicity rhythm of this drug.

Pharmacological modulation of cisplatin toxicity rhythms with buthionine sulfoximine in mice bearing pancreatic adenocarcinoma (PO3)

In a previous report, we showed that the circadian rhythm of cisplatin (cis-diamminedichloroplatinum, CDDP) toxicity in healthy mice was modified by buthionine sulfoximine (BSO), a specific inhibitor of glutathione (GSH) synthesis. In the present study, the effects of BSO on the rhythms of CDDP toxicity and antitumor efficacy were investigated in mice bearing a transplantable pancreatic adenocarcinoma (PO3). B6D2F1 mice were inoculated with two 4 mm3 tumor fragments, one in each flank, then were synchronized with an alteration of 12 h of light (L) and 12 h of darkness (D) (LD 12:12). Three weeks later, a single dose of CDDP (12 mg/kg i.v.) was injected at 3 h, 7 h, 11 h, 15 h, 19 h, or 23 h after light onset (HALO) with or without prior BSO (450 mg/kg i.p. 4 h earlier). The antitumor activity of CDDP as assessed by tumor weight change and tumor growth delay was weak in this tumor model irrespective of prior BSO administration or CDDP dosing time. Nevertheless, toxic effects of CDDP as gauged by body weight loss or survival varied significantly according to CDDP dosing time. Body weight loss was least in mice receiving CDDP alone at the mid-to-late active span. Survival rate was 97% in mice treated with CDDP alone and 47% in those receiving prior BSO (chi 2 = 23.6, p < .0001). BSO pretreatment further shifted the period of survival or body weight change from 24 h to (10 + 24)h, an effect similar to that earlier reported in healthy mice. Thus, PO3 tumor at a measurable stage altered neither the circadian rhythm in CDDP toxicity nor the ultradian rhythm in the toxicity of BSO-CDDP combination. The results suggest that rhythms in target tissues for drug actions can be manipulated with biochemical modulators, thus partly escaping central clock control.

Pharmacologic restoration of suppressed temperature rhythms in rats by melatonin, melatonin receptor agonist, S20242, or 8-OH-DPAT

Endogenous circadian rhythms in body temperature and locomotor activity rhythms are suppressed in Sprague-Dawley rats exposed to prolonged continuous light, possibly as a result of a profound alteration of the melatonin secretion rhythm. The ability to restore circadian system function with either exogenous melatonin, or melatonin receptor agonist S20242 (N-[2-(7-methoxy napth-1-yl)ethyl] propionamide), or 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), was investigated under these conditions. Seven rats received a daily 6-h intravenous infusion of melatonin (0.01 mg kg(-1)) for 10 days, which generates a nearly physiological circadian rhythm of urinary 6-sulfatoxy-melatonin, the main urinary metabolite of melatonin. Nevertheless, there was no effect on body temperature or locomotor activity rhythms. Then, 49 rats received daily subcutaneous melatonin (0.01, 1 or 5 mg kg(-1) day(-1)), S20242 (1 or 5 mg kg(-1) day(-1)) or 8-OH-DPAT (5 mg kg(-1) day(-1)) for 30 days. The circadian rhythm in body temperature was restored by subcutaneous melatonin or by S20242 as a function of the dose or by 8-OH-DPAT. The effect started within the first 10 days of treatment and persisted for I to 3 weeks following the end of treatment in 8 of 10 rats receiving melatonin, in 9 of 11 rats treated with S20242 and in 1 of 4 rats treated with 8-OH-DPAT. Activity was less susceptible to entrainment than temperature with these drugs, since circadian rhythmicity was restored in only 2 of 6 rats treated with melatonin and in 1 of 4 rats treated with 8-OH-DPAT. These data demonstrate a specific action of subcutaneous melatonin, S20242 or 8-OH-DPAT on temperature rather than on activity rhythms. This differential effect on two major outputs of the suprachiasmatic nucleus further supports the existence of two independent oscillators in this hypothalamic circadian clock, which may be considered as separate pharmacological targets in the circadian system.

Irinotecan-induced immune thrombocytopenia

BACKGROUND

Irinotecan is currently used as second-line chemotherapy for advanced colorectal cancer. We report a case of severe thrombocytopenia after Irinotecan, suggesting an immune mechanism, in a 53-year-old patient.

PATIENTS AND METHODS

The patient's sera were screened for platelet antibodies with an indirect platelet immunofluorescence test (PIIFT). The monoclonal antibody immobilization of platelet antigen assay (MAIPA) was used to characterize the antibody target.

RESULTS

We detected an IgG platelet antibody in the patient's serum in the presence of Irinotecan by means of PIIFT, and not in the presence of SN-38, its active metabolite. The specificity of the binding was asserted after CD32 MoAb blockade. The platelet binding site could not be strictly identified with MAIPA and immunoblotting but GpIIb/IIIa can be excluded after experiments with Glanzmann platelets.

CONCLUSION

This case can be considered the first documented Irinotecan-induced immune thrombocytopenia.

Circadian-based effects of AcSDKP, with or without rhG-CSF on hematologic toxicity of chemotherapy in mice

The hematologic toxicity of arabinosylcytosine (Ara-C) and carboplatin (CBDCA) as well as the stimulating effect of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on murine bone marrow vary according to their dosing time along the 24-h time scale. In the present study, we investigated whether the tolerability of Ara-C or CBDCA, given at their least toxic circadian time, could be improved further with AcSDKP, a negative regulator of hemopoiesis, rhG-CSF or both. A total of 228 B6D2F1 mice received once-daily injection of either Ara-C (42 mg/kg/d s.c.) for 7 d (d 0-6) at 8 hours after light onset - HALO) or CBDCA (40 mg/kg/d i.p.) for 5 d (d 2-6) at 16 HALO. AcSDKP (24 microg/d) was continuously infused for 7 d (d 0-6), using an osmotic minipump. rhG-CSF (400 microg/kg/d s.c.) was injected for 4 d (d 9-12) at 9 HALO. Subgroups of mice were sacrificed at 3 HALO on various days following treatment. AcSDKP significantly increased CFU-GM count on d 7 and leukocyte, neutrophil and monocyte counts on d 13 and d 16 compared to Ara-C alone. Also, rhG-CSF produced similar protective effects to those of AcSDKP with regard to leukocyte and CFU-GM counts. The combination of AcSDKP with rhG-CSF induced a further increase in total leukocytes and their subsets as compared to either agent alone, but did not alter the CFU-GM counts. Neither AcSDKP nor rhG-CSF nor their combination reduced CBD CA-induced hematological toxicity. In conclusion, AcSDKP or rhG-CSF administration further improved the tolerability of Ara-C beyond that already achieved with optimal circadian timing, while no such effect was observed in mice receiving CBDCA at the dose used. The results warrant further exploration of chronopharmacologic delivery schedules combining Ara-C with AcSDKP.

Persistent T lymphocyte rhythms despite suppressed circadian clock outputs in rats

Circadian rhythms in circulating leukocyte and lymphocyte counts persisted with halved amplitudes in constant light (LL) of 300 lx intensity for 8 wk, whereas circadian rhythms in body temperature, locomotor activity, and plasma catecholamines were completely suppressed. Subsequent exposure to constant darkness (DD) normalized all circadian rhythms within 2 wk. Rhythms in circulating T lymphocyte subsets were studied in LL or DD using double labeling with monoclonal antibodies and flow cytometry. Circadian rhythms were suppressed for leukocytes and lymphocytes but were maintained for both T helper cells (Th) and T cytotoxic cells (Ts) lymphocytes after 11 wk in LL. A group 24-h rhythm was only validated for total lymphocytes after 16 wk in LL. However, individual total, Th, and Ts lymphocytes maintained their usual respective phase relationships in each rat. The alteration of immune cell circulatory rhythms likely stemmed from a progressive loss of circadian synchronization among rats kept in LL. Conversely, after 11 or 16 wk in DD, leukocytes and lymphocyte subsets circadian rhythms were maintained. Thus catecholamines do not drive circulatory T cell rhythms. The loss of coupling between T lymphocyte rhythms and three major outputs of the circadian system further supports the hypothesis of an independent immunologic oscillator.