Assessment of dose-effect and therapeutic time window in preclinical studies of rhEGF and GHRP-6 coadministration for stroke therapy.

BACKGROUND: Stroke continues to be a leading cause of mortality and morbidity worldwide, and novel therapeutic options for ischaemic stroke are urgently needed. In this context, drug combination therapies seem to be a viable approach, which has not been fully explored in preclinical studies. OBJECTIVES: In this work, we assessed the dose-response relationship and therapeutic time window, in global brain ischaemia, of a combined therapeutic approach of recombinant human epidermal growth factor (EGF) and growth hormone-releasing peptide-6 (GHRP-6). METHODS: Mongolian gerbils underwent 15 minutes occlusion of both common carotid arteries. Four different doses of rhEGF, GHRP-6 and these combined agents were intraperitoneally administered immediately after the onset of reperfusion. Having identified a better response with both agents, rhEGF+GHRP-6 were administered at 2, 4, 6, 8 or 24 hours after the onset of reperfusion to assess the time window of effectiveness. Animals were evaluated daily for neurological deficits. Three days post-occlusion, the animals were sacrificed and 2,3,5-triphenyltetrazolium chloride was used to quantify infarcted tissues. RESULTS: The coadministration of rhEGF and GHRP-6 at doses of 100 and 600 µg/kg, respectively, administered up to 4 hours following the ischaemic insult, significantly improved survival and neurological outcome, and reduced infarct volume compared with vehicle treatment. These results are considered as an additional proof of concept as supporting a combined therapeutic approach and justify the further development of this preclinical research.

Erythropoietin: still on the neuroprotection road.

Acute stroke is one of the major causes of death and disabilities. Since the 1980s many clinical studies have been conducted to evaluate neuroprotective approaches to treat this important brain vascular event. However, to date the only drug approved (recombinant tissue plasminogen activator [rtPA]) represents a thrombolytic, nonneuroprotective approach. An important neuroprotective strategy is based on erythropoietin (EPO). Exogenously administered EPO exhibits neuroprotective effects in numerous animal models, through the activation of anti-apoptotic, anti-oxidant and anti-inflammatory pathways as well as through the stimulation of angiogenic and neurogenic events. The capability of EPO to cross the blood-brain barrier after systemic administration and its effective therapeutic window are advantages for human acute stroke therapy. However, a multicenter stroke trial where recombinant human EPO (rhEPO) was combined with rtPA had negative outcomes. The present paper reviews the EPO neuroprotective strategy and its mechanisms in ischemic stroke and in other human nervous system diseases.

Coadministration of epidermal growth factor and growth hormone releasing peptide-6 improves clinical recovery in experimental autoimmune encephalitis.

PURPOSE: Multiple sclerosis is a complex and devastating autoimmune disease of the central nervous system. Up to now, a constellation of candidate drugs have been evaluated with no major success. Experimental Autoimmune Encephalitis (EAE) is the animal counterpart that reproduces critical features of the human MS process. The aim of the present work is to study a possible therapeutic effect of epidermal growth factor (EGF) and growth hormone releasing peptide-6 (GHRP(6)) coadministration in mild and severe EAE. METHODS: Mild and severe forms of EAE were generated immunizing rats and mice with xenogeneic spinal cord homogenate and with the encephalitogenic peptide MOG(p35-35), respectively. EGF and GHRP(6) alone or combined were administered in therapeutic and prophylactic schedules. A clinical score was established to follow-up the animals during the disease period. Malondialdehyde (MDA) serum concentration and insulin like growth factor-1 (IGF-1) relative level from brain tissue were determined. RESULTS: Only the combined EGF+GHRP(6) therapy reduced the clinical score in mild as well in severe EAE forms. The combination also improved the survival rate in nearly 100% of the severe EAE animals. In addition to these effects, there was an increase in the brain IGF-1 transcript and a decrease of serum MDA. CONCLUSIONS: EGF+GHRP(6) proved to be effective in improving the natural course of both mild and severe EAE. Accordingly, the treatment reduces inflammatory infiltration and microvascular damage, which may be associated to the attenuation of the lipid peroxidation process and the transcriptional enhancement of IGF-1, a major pro-survival factor for brain cells.

Systemic and skin toxicity in Cercopithecus aethiops sabaeus monkeys treated during 26 weeks with a high intravenous dose of the anti- epidermal growth factor receptor monoclonal antibody Nimotuzumab.

Nimotuzumab (h-R3) is a humanized anti-epidermal growth factor receptor monoclonal antibody (mAb) registered for treating head and neck tumours. The present study was designed to evaluate the systemic and skin toxicity of chronic intravenous administration of the h-R3 in a relevant species demonstrated by comparing the h-R3 binding affinity constants (Kd) in microsomal placental fractions from Homo sapiens and Cercopithecus aethiops monkeys using an EGF-Receptor radioligand competition assay. The Kd obtained for Nimotuzumab were 9.1 x 10(-8) M for monkeys and 4.5 x 10(-8) M for humans. Monkeys (n = 18) were distributed into 3 groups with 3 animals of each sex in each group. Group I received saline; group II received 2.85 mg/kg of h-R3; and group III received 28.57 mg/kg of the h-R3, which represent 1 and 10 times the human dose, and they were weekly intravenously treated during 26 weeks. During the study there were no deaths. Electroneurophysiological, sanguine chemistry and haematological results did not evidence alterations. Areas of haematomas, probably related with the administration procedure, were observed at the administration zones of all animals. The electrocardiography study showed at the end of the study a slight increase in the cardiac frequency of four treated animals without other signs. Unexpectedly, skin biopsies and a detailed clinical inspection of the animals did not detect the presence of cutaneous rash or any other skin toxicity sign reported for the majority of the anti-EGF-R monoclonal antibodies. It is concluded that doses up to 28.5 mg/kg of h-R3, intravenously administered during 26 weeks to Cercopithecus aethiops monkeys, do not produce considerable toxic effects.