A single dose of AC102 restores hearing in a guinea pig model of noise-induced hearing loss to almost prenoise levels.

Although sudden sensorineural hearing loss (SSNHL) is a serious condition, there are currently no approved drugs for its treatment. Nevertheless, there is a growing understanding that the cochlear pathologies that underlie SSNHL include apoptotic death of sensory outer hair cells (OHCs) as well as loss of ribbon synapses connecting sensory inner hair cells (IHCs) and neurites of the auditory nerve, designated synaptopathy. Noise-induced hearing loss (NIHL) is a common subtype of SSNHL and is widely used to model hearing loss preclinically. Here, we demonstrate that a single interventive application of a small pyridoindole molecule (AC102) into the middle ear restored auditory function almost to prenoise levels in a guinea pig model of NIHL. AC102 prevented noise-triggered loss of OHCs and reduced IHC synaptopathy suggesting a role of AC102 in reconnecting auditory neurons to their sensory target cells. Notably, AC102 exerted its therapeutic properties over a wide frequency range. Such strong improvements in hearing have not previously been demonstrated for other therapeutic agents. In vitro experiments of a neuronal damage model revealed that AC102 protected cells from apoptosis and promoted neurite growth. These effects may be explained by increased production of adenosine triphosphate, indicating improved mitochondrial function, and reduced levels of reactive-oxygen species which prevents the apoptotic processes responsible for OHC death. This action profile of AC102 might be causal for the observed hearing recovery in in vivo models.

Intratympanic Substance Distribution After Injection of Liquid and Thermosensitive Drug Carriers: An Endoscopic Study.

OBJECTIVE: In the treatment of inner ear conditions, intratympanic injection emerges as an important drug delivery method. Novel compounds designed for intratympanic injection are routinely loaded in viscous drug carriers. To date, it is unclear if they can freely distribute in the middle ear. The aims of this study were to investigate the middle ear distribution of different drug carriers during intratympanic injection and to determine an optimal injection method for thermosensitive hydrogels. METHODS: Twenty-one human temporal bones were intratympanically injected with fluid drug carriers or poloxamer-407 hydrogels at different tympanic membrane injection sites (inferior, anterior-superior) using different needle types (Whitacre, Quincke). Fluid distribution was evaluated via an endoscopic view. Injection volume, duration, backflow, and overall safety were analyzed. RESULTS: Liquid drug carriers distribute effortlessly in the middle ear, whereas an additional ventilation hole is advantageous when applying thermosensitive hydrogels. The round window is coated with required volumes between 150 and 200 µl, irrespective of the injection position. Required volumes to also coat the stapedial footplate ranged from 310 to 440 µl. Use of the Whitacre-type needle reduced backflow to the ear canal and enabled longer tympanic membrane visibility when no additional ventilation hole was placed. CONCLUSION: Intratympanic injection is a safe and reliable method for the application of thermosensitive hydrogels. The round window niche is readily filled regardless of the injected formulation and injection position. Although fluid drug carriers distribute effortlessly in the middle ear, the placement of an additional ventilation hole might facilitate the application of viscous hydrogels.

Inhibition of TGF-beta2 with AP 12009 in recurrent malignant gliomas: from preclinical to phase I/II studies.

Transforming growth factor-beta2 (TGF-beta2) is known to suppress the immune response to cancer cells and plays a pivotal role in tumor progression by regulating key mechanisms including proliferation, metastasis, and angiogenesis. For targeted protein suppression the TGF-beta2-specific antisense oligodeoxynucleotide AP 12009 was developed. In vitro experiments have been performed to prove specificity and efficacy of the TGF-beta2 inhibitor AP 12009 employing patient-derived malignant glioma cells as well as peripheral blood mononuclear cells (PBMCs) from patients. Clinically, the antisense compound AP 12009 was assessed in three Phase I/II-studies for the treatment of patients with recurrent or refractory malignant (high-grade) glioma WHO grade III or IV. Although the study was not primarily designed as an efficacy evaluation, prolonged survival compared to literature data and response data were observed, which are very rarely seen in this tumor indication. Two patients experienced long-lasting complete tumor remissions. These results implicate targeted TGF-beta2-suppression using AP 12009 as a promising novel approach for malignant gliomas and other highly aggressive, TGF-beta-2-overexpressing tumors.

Targeted tumor therapy with the TGF-beta 2 antisense compound AP 12009.

TGF-beta overexpression is a hallmark of various malignant tumors. This is due to the pivotal role of TGF-beta as it regulates key mechanisms of tumor development, namely immunosuppression, metastasis, angiogenesis, and proliferation. We have developed a new immunotherapeutic approach for the treatment of malignant tumors based on the specific inhibition of TGF-beta2 by the antisense oligodeoxynucleotide AP 12009. After providing preclinical proof of concept, we assessed safety and efficacy of AP 12009 in clinical phase I/II open-label dose escalation studies in high-grade glioma patients. Median survival time after recurrence exceeded the up to date literature data for chemotherapy. A phase I/II study in pancreatic carcinoma and malignant melanoma is currently ongoing. Our results implicate targeted TGF-beta2 suppression as a promising therapeutic approach for malignant tumor therapy.

Intracerebral and intrathecal infusion of the TGF-beta 2-specific antisense phosphorothioate oligonucleotide AP 12009 in rabbits and primates: toxicology and safety.

Here, we provide first evidence that long-term continuous infusion of highly purified antisense phosphorothioate oligodeoxynucleotides (S-ODN) into brain parenchyma is well tolerated and thus highly suitable for in vivo application. AP 12009 is an S-ODN for the therapy of malignant glioma. It is directed against human transforming growth factor-beta (TGF-beta2) mRNA. In the clinical setting, AP 12009 is administered intratumorally by continuous infusion directly into the brain tumor. In view of this clinical application, the focus of our data is on local toxicology studies in rabbits and monkeys to evaluate the safety of AP 12009. AP 12009 was administered either by intrathecal bolus injection into the subarachnoidal space of the lumbar region of both cynomolgus monkeys and rabbits or by continuous intraparenchymatous infusion directly into the brain tissue of rabbits. Intrathecal bolus administration of 0.1 ml of 500 microM AP 12009 showed neither clinical signs of toxicity nor macroscopically visible or histomorphologic changes. After a 7-day intraparenchymatous continuous infusion of 500 microM AP 12009 at 1 microl/h in rabbits, there was no evidence of toxicity except for local mild to moderate lymphocytic leptomeningoencephalitis. Additionally, AP 12009 showed good tolerability in safety pharmacology as well as in acute toxicity studies and 4-week subchronic toxicity studies in mice, rats, and monkeys. This favorable safety profile proves the suitability of AP 12009 for local administration in brain tumor patients from the point of view of toxicology.