A phase II study of pemetrexed in patients (pts) with advanced neuroendocrine tumors (NETs)

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Background: Traditional antifolates such as 5-florouracil have been associated with only modest activity in NETs. Pemetrexed is a multitargeted antifolate active in diseases not known to be responsive to other antifolates. We performed a prospective phase II study of pemetrexed in pts with advanced NETs to assess response, toxicity, and survival. Methods: Pts were treated with Pemetrexed administered intravenously at a dose of 500 mg/m2 every 21 days. To reduce toxicity, folic acid and vitamin B12 supplementation were mandatory. Pts were also treated with oral dexamethasone 4 mg twice daily the day prior to, day of, and day after pemetrexed administration. The study utilized a two-step design, with an initial accrual phase of 17. Pts were required to have metastatic neuroendocrine tumors (excluding small cell carcinoma), and preserved hematologic, renal, and hepatic function. Treatment with prior chemotherapy was allowed; pts receiving octreotide remained on octreotide at a stable dose level during study therapy. Results: 17 pts were enrolled with the following characteristics: M: F=4:13. median age 56 (range 38 to 72); ECOG Performance Status 0/1/2=4/12/1. Tumor types included carcinoid n=12(71%) and islet cell n=5(29%). 17 pts received treatment for a median of three, 21-day cycles; the median time on study was 10 weeks. Grade 3–4 toxicities included: fatigue n=8(47%), leukopenia n=7 (41%), neutropenia n=6 (35%), elevated alkaline phosphatase n=4 (23%), thrombocytopenia n=3 (17%), lymphopenia n=3 (17%), pneumonitis n=2 (11%), hyponatremia n=2 (11%), dyspnea n=1 (5%), hyperbilirubinemia n=1 (5%), weight loss n=1 (5%), diarrhea n=1 (5%), elevated ALT/SGPT n=1 (5%), edema n=1 (5%), weakness n=1 (5%), grade 4 proteinuria n=1 (5%). 15 pts were evaluable for response; the best treatment response was stable disease (n=9;), the remaining 6 pts experienced progressive disease as their best response to therapy. Accrual to the study was halted due to lack of observed antitumor activity. Conclusions: Pemetrexed does not have significant antitumor activity in pts with advanced NET.

No significant financial relationships to disclose.

Prenatally protein-malnourished rats are less sensitive to the amnestic effects of medial septal infusions of chlordiazepoxide

Evidence is mounting that prenatal protein malnutrition affects the physiological properties of the GABAergic neurotransmitter system in rats. To investigate the functional behavioral consequences of these changes, chlordiazepoxide (CDP, a positive modulator of the GABA(A) receptor) was applied directly to the medial septum and the amnestic response appraised. In adulthood, male offspring of rats provided with a protein-deficient diet (6% casein) for 5 weeks prior to mating and throughout pregnancy underwent stereotaxic surgery to implant steel cannulae aimed at the medial septum. After recovery, spatial learning performance in the submerged platform version of the Morris water maze task was assessed immediately following a 1 microl infusion of either artificial cerebrospinal fluid (aCSF), or one of three doses of CDP (15, 30 and 60 nmol). Well-nourished control rats demonstrated a robust amnestic response to intraseptal CDP. During task acquisition, well-nourished rats administered each of the doses exhibited significantly longer escape latencies than those given aCSF. On the probe trial (platform removed) a lower proportion of time was spent in the target quadrant (all three doses) at a greater average distance from the former platform location (30 and 60 nmol doses). In contrast, prenatally malnourished rats exhibited a muted sensitivity to CDP, most notable at the 30 nmol dose. These findings provide further support for functional changes within the GABAergic system consequent to malnutrition.

Prenatal protein malnourished rats show changes in sleep/wake behavior as adults

Prenatal protein malnutrition significantly elevates brain levels of serotonin in rats, and these levels remain elevated throughout their lives. This biogenic amine is involved in the regulation of many physiological functions, including the normal sleep/wake cycle. The present study examined the effects of prenatal protein malnutrition on the sleep/wake cycle of freely moving adult rats. Six prenatally protein malnourished (6% casein) and 10 well-nourished (25% casein) male rats (90-120-day-old) were chronically implanted with a standard set of electrodes (to record cortical electroencephalogram, neck muscle electromyogram, electrooculogram, and hippocampal theta wave) to objectively measure states of sleep and wakefulness. Six-hour polygraphic recordings were made between 10.00 and 16.00 h; a time when the rats normally sleep. Prenatally malnourished rats spent 20% more time in slow wave sleep (SWS) compared to the well-nourished rats. The total percentage of time spent in rapid eye movement (REM) sleep was 61% less in prenatally malnourished rats compared to well-nourished control rats. These findings demonstrate the adverse consequences of prenatal protein malnutrition on the quality and quantity of adult sleep in rats. These sleep changes are potentially detrimental to normal social behavior and cognitive functions. Prenatally malnourished rats are an excellent animal model to study the role of endogenous serotonin in the regulation of the normal sleep/wake cycle.

Chlordiazepoxide-induced spatial learning deficits: dose-dependent differences following prenatal malnutrition

The sensitivity of prenatally protein-malnourished rats to the amnestic properties of the benzodiazepine (BZ) receptor agonist, chlordiazepoxide (CDP), was studied in the male offspring of rats provided with a protein-deficient diet (6% casein) for 5 weeks prior to mating and throughout pregnancy. Rats were tested during acquisition of the submerged platform version of the Morris water maze task using three systemic doses of CDP (3.2, 5.6, and 7.5 mg/kg i.p.) at two ages (day 30 and day 90). At 30 days, prenatally malnourished rats showed less sensitivity to the amnestic effect of the 5.6-mg/kg dose when compared with well-nourished controls by displaying shorter swim paths during acquisition and a more selective search of the target quadrant upon removal of the platform (probe trial). At 90 days, prenatally malnourished rats again showed less sensitivity to CDP at a dose of 5.6 mg/kg, but more sensitivity to the 3.2-mg/kg dose (indicated on the probe trial). No obvious relationship was identified between the nutritional group differences in behavioral sensitivity to CDP at 90 days and their BZ receptor density in the hippocampus or medial septum. It can be concluded that prenatal malnutrition alters the amnestic response to CDP in a dose-dependent and developmentally specific manner, thus providing further support for functional changes within the GABAergic system subsequent to malnutrition.