Salmonella typhimurium-based Bacteriotherapy for Orphan Benign Tumors: Neurofibromatosis Type II (NF2)

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Neurofibromatosis type 2 (NF2) is a rare genetic disorder that affects about 1 in 25,000 individuals globally. While usually benign, these tumors result in severe morbidity and mortality in affected individuals. Almost all NF2 patients lose their hearing, and many lose the ability to walk and even to see. NF2 patients’ average age at death is 36 years, many of whom die in adolescence or early adulthood from their disease. NF2 is an orphan indication and represents a major unmet medical need, thus supporting an FDA Fast Track designation. NF Bio estimates the NF2 commercial opportunity to exceed US$1B in annual peak year sales. Success in NF2 treatment will also lead to testing in other benign and schwannoma-related neoplasms such as NF1. Operative resection and radiotherapy are the current standards of care. However, these treatments have major limitations. Resection can lead to a significant sensory loss including deafness, pain, facial paralysis, and motor dysfunction. Resection also is not always possible due to the risk of nerve or brain stem damage. Radiotherapy can be contraindicated due to the risk of malignant transformation and typically does not eliminate the schwannoma. Affected individuals typically have multiple schwannomas with tumors arising throughout life, further increasing disease-associated suffering and limiting the utility of surgical resection. There is no approved pharmaceutical therapy and a limited clinical trial pipeline. NF Bio has developed an NF2 bacteriotherapy that utilizes intra-tumoral (i.t.) injection of attenuated S. typhimurium, delivered in an image-guided fashion (MRI or ultrasound) by neurosurgeons, otolaryngologists, pain medicine physicians, or interventional radiologists Use of this bacterial therapy for schwannomas is justified by the fact that Salmonella thrives in the hypoxic areas of highly vascularized tissues, which is a hallmark of NF2 schwannomas, and its anti-tumor cytotoxic mechanisms do not require tumor cell replication. NF Bio is the first to develop a bacteria-based therapy for the treatment of NF2. We have demonstrated in animal models that i.t. injection of attenuated S. typhimurium decreases the volume of the injected tumor through direct cytotoxic and anti-angiogenic effects; importantly, it also induces a systemic immune response that targets distal tumors and a memory response that prevents further development of new lesions. This intervention has a lower risk of neurologic damage than operative resection due to the targeting mechanisms and engineered safety mechanisms that will be developed in this proposal. In the proposed Phase I work, NF Bio will develop a next-generation bacterial therapy that enhances direct tumor killing and induce immune-mediated killing. In future Phase II grant work, we will select a Development Candidate (DC) based on in vitro and in vivo data, and conduct toxicology and biodistribution studies to enable a US Investigational New Drug (IND) application.