Capecitabine plus oxaliplatin (XELOX) followed by capecitabine plus irinotecan (XELIRI) in a sequential schedule in first-line metastatic colorectal cancer (MCRC): a phase II multicenter study

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Background: In phase II trials, XELOX and XELIRI were highly active and well tolerated in first-line MCRC. The aim of this study is to explore the efficacy and safety of XELOX followed by XELIRI as first-line treatment in MCRC. Specifically, we wanted to evaluate the impact of sequential scheduling on the dose-limiting neurotoxicity associated with oxaliplatin accumulation. Methods: Eligible patients (pts) had histologically or cytologically confirmed MCRC, ECOG PS ≤ 2 and adequate bone marrow, renal and hepatic function. Prior chemotherapy for MCRC was not allowed. Pts received 4 cycles of XELOX (capecitabine 1000mg/m2 orally bid d1–14 + oxaliplatin 130mg/m2 i.v. d1, q3w) followed by 4 cycles of XELIRI (capecitabine 1000mg/m2 bid d1–14 + irinotecan 240mg/m2 i.v. d1, q3w). This sequential schedule was repeated until unacceptable toxicity or disease progression. Results: Of the 35 pts analized to date: M/F (69%/31%); median age 68 years (range 41–78); ECOG PS 0–1 (94%); surgery (77%) and adjuvant chemotherapy (31%). 240 cycles (median 6, range 1–16) have been administered. 35 pts received XELOX (123 cycles, median 4), and 21 pts received XELIRI (83 cycles, median 4) in the first sequential schedule. In the second sequential schedule 6 pts received XELOX (22 cycles, median 4) and 4 pts received XELIRI (12 cycles, median 3.5). Median relative dose intensity was 88% for XEL, 96% for OX and 92% for IRI. In 27 efficacy evaluable pts, the ORR was 48% (95% CI, 29–67%). Eight pts were not evaluable due to adverse events (n=6), ongoing treatment (n=1) and lost of follow up (n=1). Conclusions: This sequential schedule is active and well tolerated in first-line MCRC. The improvement/recovery of the oxaliplatin-related neurotoxicity during the XELIRI phase is also promising and allows the re-treatment with oxapliplatin in the next sequence without accumulating neurotoxicity. Final results will be presented at the meeting. [Table: see text]

No significant financial relationships to disclose.

Influence of hormonal status on enkephalin-degrading aminopeptidase activity in the HPA axis of female mice

Opioids are involved in the regulation of hypothalamus-pituitary-adrenal (HPA) axis activity under physiological conditions. In the present work, we analyzed the influence of ovariectomy and estradiol (E), progesterone (P) or estradiol plus progesterone (E+P) replacement on soluble (S) and membrane-bound (MB) enkephalin-degrading aminopeptidase activity (EDA) in the HPA axis. Female mice (Balb/C) were distributed in 15 groups of 10 animals each: sham-operated controls (C), ovariectomized controls (OV-C), and ovariectomized mice treated with increasing doses of E (10, 20 or 40 mg/kg), P (100, 200 or 400 mg/kg) or E+P (10+100, 20+200 or 40+400 mg/kg). In hypothalamus, ovariectomy increased both S and MB EDA activities, whereas E replacement returned them to control levels, although MB EDA activity increased again after the replacement with 40 mg/kg E. P replacement increased S EDA activity, but returned MB EDA activity to control levels. The replacement of E+P returned both S and MB EDA activities to control levels, although MB EDA activity was lower than control values after the replacement with 10+100 mg/kg E+P. In pituitary, neither ovariectomy nor the replacement of E or E+P changed S EDA, although the highest concentrations of P increased S EDA activity. However, ovariectomy increased MB EDA and E replacement returned the activity to control or below control levels, depending on the concentration used. However, P administration returned the activity to control or below control levels depending on the concentration used, although 200 mg/kg P had no effects on MB EDA. E+P replacement returned pituitary MB EDA activity to control levels. In adrenal glands, ovariectomy did change either S or MB EDA. However, E, P or E+P replacement decreased S EDA activity in different degrees, depending of the dose administrated. No changes were detected in MB EDA after hormone replacement. These results indicate that female steroid hormones influence EDA activity at different levels of HPA axis.

Effects of orchidectomy and testosterone replacement on mouse pyrrolidone carboxypeptidase activity in the HPA axis

Pyrrolidone carboxypeptidase, also known as pyroglutamyl aminopeptidase, removes pyroglutamyl terminal residues from biologically active peptides such as thyrotropin-releasing hormone. The aim of the present work was to study the influence of orchidectomy and testosterone replacement on soluble (pyrrolidone carboxypeptidase type I) and membrane-bound (pyrrolidone carboxypeptidase type II) activities in the hypothalamus-pituitary-adrenal axis. Forty male mice (Balb/C) were distributed into five groups: sham-operated controls, orchidectomized, and orchidectomized treated with increasing doses of testosterone in each group (3, 6 and 12 mg/kg). In the hypothalamus, orchidectomy increased pyrrolidone carboxypeptidase type I, whereas the highest dose of testosterone returned this activity to control levels. In the pituitary, neither pyrrolidone carboxypeptidase type I nor type II activities changed after orchidectomy, although both activities increased after administration of testosterone in both cases. On the other hand, orchidectomy increased pyrrolidone carboxypeptidase type I and type II activities in adrenal glands, while testosterone replacement returned it to control levels. These results suggest that testosterone differentially modulates pyrrolidone carboxypeptidase type I and type II activities, and therefore also their endogenous substrate regulation. Thus, the influence of sex hormones in the physiology of the HPA axis through the modulation of the Pyrrolidone carboxypeptidase type I and type II activities is of great importance on stress and neuropathology associated with HPA dysfunction

Effects of orchidectomy and testosterone replacement on mouse enkephalin-degrading aminopeptidase activity in the HPA axis

Opiates are involved in the regulation of several functions in the hypothalamus-pituitary-adrenal (HPA) axis under physiological conditions. The aim of the present work is to study the influence of orchidectomy and testosterone (T) replacement on soluble (S) and membrane bound (MB) enkephalin-degrading aminopeptidase (EDA) activities in the HPA axis. Forty male mice (Balb/C) were distributed in five groups: sham-operated control (C), orchidectomized (OR-C), and orchidectomized treated with increasing doses of T (3, 6 or 12 mg/kg). In hypothalamus, orchidectomy did not modify either S or MB EDA, although T replacement increased S but not MB EDA. In pituitary, neither S nor MB EDA activities changed with orchidectomy, although both activities changed after T replacement. On the other hand, in adrenal glands, orchidectomy increased S and MB EDA activities, whereas T replacement returned both activities to control levels. These results suggest a direct effect of T in S and MB EDA activities and therefore, an influence on their endogenous substrates regulation.

[Physiology of the neuropeptides]

In the present review, the characteristics of mammalian neuropeptides have been studied. Neuropeptides are widely distributed not only in the nervous system but also in the periphery. They are synthesised by neurons as large precursor molecules (pre propeptides) which have to be cleaved and modified in order to form the mature neuropeptides. Neuropeptides may exert actions as neurotransmitters, neuromodulators and/or neurohormones. In the neurons, they coexist with classic transmitters and often with other peptides. After their releasing, they bind to especific receptors to exert their action in the target cell. Most of these receptors belongs to a family of G protein coupled receptors. Finally, peptidases are the enzymes involved in the degradation of neuropeptides. Conclusions. In the last years, the number of known neuropeptides and the understanding of their functions have been increased. With these data, present investigations are looking for the treatment of different pathologies associated with alterations in the physiology of neuropeptides.