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Biotech / Medical : Xenova (XNVA) -- Ignore unavailable to you. Want to Upgrade?

To: nigel bates who wrote (51)	2/24/2004 4:07:31 AM
From: tuck	Read Replies (1) \| Respond to of 173

Transmid Boy, has this one been kicking around for a while: >>J Neurosurg. 1994 Mar;80(3):520-6. Efficacy of direct intratumoral therapy with targeted protein toxins for solid human gliomas in nude mice. Laske DW, Ilercil O, Akbasak A, Youle RJ, Oldfield EH. Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland. Targeted protein toxins are a new class of reagents with the potential for great tumor selectivity and cytotoxic potency. Two such compounds were studied: 1) Tf-CRM107, a conjugate of human transferrin (Tf) and diphtheria toxin with a point mutation (CRM107); and 2) 454A12-rRA, a conjugate of a monoclonal antibody (454A12) to the human Tf receptor and recombinant ricin A chain (rRA). Both compounds are potent and specific in killing human glioblastoma cell lines in vitro. The authors investigated the activity of these reagents administered intratumorally against solid U251 MG human gliomas in vivo. Nude mice with established U251 MG flank tumors (0.5 to 1.0 cm in diameter) were randomly assigned to be treated with 100-microliters intratumoral injections of Tf-CRM107 (10 micrograms) or 454A12-rRA (10 micrograms), equimolar doses of CRM107 (4.3 micrograms), 454A12 antibody (7.5 micrograms), or rRA (1.5 micrograms), or phosphate-buffered saline (PBS) every 2 days for a total of four doses. Tumor volume and animal weight were assessed by a blinded observer before each treatment and biweekly for 30 days after initiating therapy. With Tf-CRM107 administration, tumor regression of greater than 95% occurred by Day 14 (p < 0.01) and tumors did not recur by Day 30. Treatment with 454A12-rRA caused a 30% decrease in tumor volume by Day 14 (p < 0.01). Treatment with equimolar doses of the unconjugated targeted protein toxin components CRM107, 454A12, or rRA caused significant U251 MG tumor growth inhibition, but the effects were less potent than the antitumor effects of the conjugates. This study also characterized the dose-response effect of Tf-CRM107 on tumor growth and tumor weight on Day 30. Nude mice with established U251 MG flank tumors (0.5 to 1.0 cm in diameter) were treated with 100-microliters intratumoral injections of 10, 1.0, or 0.1 microgram of Tf-CRM107 or PBS every 2 days for a total of four doses. All three doses of Tf-CRM107 significantly inhibited tumor growth by Day 14 (p < 0.01) and at Day 30 (p < 0.05), with a significant dose-response relationship. This study demonstrated in vivo efficacy of the targeted toxins Tf-CRM107 and 454A12-rRA against a human glioma. With intratumoral administration, the effect of Tf-CRM107 was tumor-specific and in some animals curative. Regional therapy with these potent tumor-specific agents using direct intratumoral infusion should limit systemic toxicity and may be efficacious against brain tumors.<< >>Nat Med. 1997 Dec;3(12):1362-8. Tumor regression with regional distribution of the targeted toxin TF-CRM107 in patients with malignant brain tumors. Laske DW, Youle RJ, Oldfield EH. Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-1414, USA. We investigated regional therapy of recurrent malignant brain tumors with transferrin-CRM107, a conjugate of human transferrin (Tf) and a genetic mutant of diphtheria toxin (CRM107) that lacks native toxin binding. Physiological barriers to delivering proteins to tumor and surrounding infiltrated brain were circumvented with high-flow interstitial microinfusion. At least a 50% reduction in tumor volume on magnetic resonance imaging (MRI) occurred in 9 of 15 patients who could be evaluated (60%), including two complete responses. Peritumoral toxicity developed 1-4 weeks after treatment in three of three patients at 1.0 microg/ml, but in zero of nine patients treated at lower concentrations. No symptomatic systemic toxicity occurred. Regional perfusion with Tf-CRM107 produces tumor responses without systemic toxicity in patients with malignant brain tumors refractory to conventional therapy. Direct interstitial infusion can be used successfully to distribute a large protein in the tumor and infiltrated brain surrounding the tumor.<< >>Transferrin receptor ligand-targeted toxin conjugate (Tf-CRM107) for therapy of malignant gliomas. Weaver M, Laske DW. Department of Neurosurgery, Temple University School of Medicine, Philadelphia, PA 19140-5103, USA. The authors review the preclinical and clinical results of the ligand-targeted toxin conjugate Transferrin-CRM107 (Tf-CRM107), for the treatment of malignant gliomas. Tf-CRM107 is a conjugate protein of diphtheria toxin with a point mutation (CRM107) linked by a thioester bond to human transferrin (Tf). This conjugate exhibits potent cytotoxicity in vitro against mammalian cells expressing the transferrin receptor with activity at picomolar concentrations. Phase I clinical trial results demonstrated that Tf-CRM107, delivered via a high-flow convection method utilizing stereotactically placed catheters, produced tumor response in patients with malignant brain tumors refractory to conventional therapy without severe neurologic or systemic toxicity. The results of a Phase II study are also summarized. Tf-CRM107 treatment results in complete and partial tumor response without severe toxicity in 35% of the evaluable patients. These data warrant a Phase III study as well as continued research in the field of targeted toxin therapy. Future directions of research include optimizing Tf-CRM107 delivery to targeted brain regions, and improving the treatment efficacy by combining with other toxin conjugates targeted to different receptors.<< If these trial results have been published outside of these references, I haven't been able to find them. Cheers, Tuck