Engineering of human H-NOX as an oxygen delivery therapeutic for prolonged admini -
Engineering'of'Human'H.NOX'as'an'Oxygen'Delivery'Therapeutic'for'Prolonged'Administration' '
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Project Summary/Abstract
Omniox has developed a class of tunable oxygen-delivery agents that significantly alleviate tumor hypoxia to
enhance the efficacy of radiotherapy (RT). This family of therapeutic proteins, called H-NOX, can oxygenate
hypoxic tumors without the treatment burden and toxicity associated with earlier oxygenation therapies.
Because radiation relies on oxygen to damage DNA, the lack of oxygen in aggressive solid tumors is a major
impediment to effective treatment. Previous SBIR-funded studies resulted in the identification of an H-NOX
variant of bacterial origin, OMX-4.80, that is highly effective in penetrating and oxygenating hypoxic tumors and
enhancing tumor growth delay after single radiation treatments. OMX-4.80 does not result in cardiovascular,
renal, or hypertensive toxicities associated with hemoglobin-based oxygen carriers. The bacterial origin of the
lead candidate makes it appropriate for hypofractionated RT-such as Cyberknife" for metastatic brain and
recurrent primary brain cancer-however, its immunogenicity is incompatible with prolonged dosing schemes
(> 2 weeks) of fractionated RT in >80% of the 800,000 patients that receive RT.
In this study, we will evaluate a novel class of therapeutic oxygen carriers from human H-NOX (hH-NOX)
homologues, which have been engineered with similar oxygen delivery properties to OMX-4.80, yet remain
compatible with the prolonged treatment schedules currently used in fractionated RT. We have screened a
focused mutant library of 180 hH-NOX variants, and identified 10 candidates with promising oxygen-binding
kinetics. In Aim 1, Omniox will compare the oxygen affinity, stability and NO reactivity of this panel of 10
candidates to identify a lead candidate (and backups) with optimal biochemical properties. In Aim 2, animal
studies will be performed to characterize the pharmacokinetic, safety and immunogenicity profile of the lead
candidate. In Aim 3, using a syngeneic tumor xenograft model in immunocompetent mice developed and
tested during Omniox' preclinical development of the bacterial H-NOX, we will examine tumor biodistribution
and oxygenation of the lead hH-NOX (Aim 3A) and demonstrate reduction in primary tumor growth through
repeated hH-NOX dosing in conjunction with fractionated RT (Aim 3B).! !
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