A phase 1 trial of recombinant human IL-21 in combination with cetuximab in patients with metastatic colorectal cancer

BACKGROUND

Pre-clinical data indicate enhanced anti-tumour activity when combining recombinant human interleukin-21 (rIL-21), a class 1 cytokine, with cetuximab, a monoclonal antibody, targeting the epidermal growth factor receptor. This phase 1 trial assessed the safety and tolerability of escalating doses of rIL-21 in combination with cetuximab in chemo-naïve patients with stage IV colorectal cancer.

PATIENTS AND METHODS

Sequential cohorts of PS 0-1, asymptomatic patients, were treated weekly with cetuximab 250 mg m(-2) intravenously (i.v.) plus escalating i.v. doses of rIL-21 following an initial loading dose of cetuximab 400 mg m(-2). Initial treatment period was 8 weeks, with extension permitted in patients without disease progression.

RESULTS

In all, 15 patients were included in this study. Adverse events related to rIL-21 or rIL-21 plus cetuximab included lethargy, nausea/vomiting, stomatitis, lymphopenia and pyrexia and were mainly ≤ grade 2. One dose limiting toxicity occurred (grade 3 diarrhoea). Maximum tolerated dose was not determined because of the premature study closure. Maximum administered dose was 100 μg kg(-1) rIL-21 weekly. In all, 60% of the patients had stable disease. Immune activation was confirmed by various T- and NK-cell activation biomarkers, including dose-dependent increases in serum sCD25.

CONCLUSION

rIL-21 weekly combined with cetuximab is well tolerated at doses up to 100 μg kg(-1) and results in activation of immune response biomarkers.

Increase in neurogenesis and behavioural benefit after chronic fluoxetine treatment in Wistar rats

OBJECTIVE

Disturbances in hippocampal neurogenesis may be involved in the pathophysiology of depression and it has been argued that an increase in the generation of new nerve cells in the hippocampus is involved in the mechanism of action of antidepressants.

MATERIALS AND METHODS

Adult Wistar rats were treated with fluoxetine (10 mg/kg) 1 h, daily for 5 (subchronic) or 28 days (chronic) before the Novelty Suppressed Feeding test was performed. Cell proliferation and neurogenesis were analysed using the markers 5-bromo-deoxy-2'-uridine, Ki-67, and doublecortin.

RESULTS

A significant behavioural effect was found after 28 days of fluoxetine administration. However, no behavioural improvement was demonstrated after acute and subchronic treatment with fluoxetine. We further demonstrate that chronic antidepressant treatment increases cell proliferation as well as neurogenesis in the dentate gyrus, here using Wistar rats.

CONCLUSIONS

In further development of antidepressants, neurogenesis may serve as an important parameter to examine the efficacy and mechanism of action of novel drugs.

Arrested neuronal proliferation and impaired hippocampal function following fractionated brain irradiation in the adult rat

The generation of new neurons in the adult mammalian brain has been documented in numerous recent reports. Studies undertaken so far indicate that adult hippocampal neurogenesis is related in a number of ways to hippocampal function.Here, we report that subjecting adult rats to fractionated brain irradiation blocked the formation of new neurons in the dentate gyrus of the hippocampus. At different time points after the termination of the irradiation procedure, the animals were tested in two tests of short-term memory that differ with respect to their dependence on hippocampal function. Eight and 21 days after irradiation, the animals with blocked neurogenesis performed poorer than controls in a hippocampus-dependent place-recognition task, indicating that the presence of newly generated neurons may be necessary for the normal function of this brain area. The animals were never impaired in a hippocampus-independent object-recognition task. These results are in line with other reports documenting the functional significance of newly generated neurons in this region. As our irradiation procedure models prophylactic cranial irradiation used in the treatment of different cancers, we suggest that blocked neurogenesis contributes to the reported deleterious side effects of this treatment, consisting of memory impairment, dysphoria and lethargy.