Project Summary
Neuropathic chronic pain affects ~20 million of Americans and bears more than US$500 Billion burden on the
US economy. Moreover, the widespread use of addictive opioid painkillers for chronic pain is the major root of
the opioid abuse epidemics threatening the whole society. As only one in four patients with neuropathic pain
experiences pain relief with the current treatment options, discovery of new approaches to treating neuropathic
pain is an unmet medical need with a major impact on society. Targeting pain in peripheral neurons is a key
paradigm for effective and safe analgesia, which can naturally bypass the CNS-mediated side effects and
addiction. One of the most promising and advanced peripheral targets, angiotensin AT2 receptor is involved in
regulations of neuronal membrane excitability and neurite outgrowth of peripheral sensory neurons. Inhibition of
AT2R in PNS has shown effect in preclinical models of neuropathic pain, as well as in phase II clinical trials,
where the EMA401 drug demonstrated analgesia in patients with post-herpetic neuralgia. However, EMA401,
which had modest potency and suboptimal drug-like properties, has been terminated in May 2019 due to off-
target hepatotoxicity at high therapeutic doses. Lack of suitable AT2R candidates in pipeline calls for discovery
and development of new highly potent and safe AT2R antagonists for neuropathic pain. We have established a
structure-based drug discovery platform and used it to identify new lead chemotypes for AT2R antagonists. Our
current lead has affinity (Ki =56 nM) on par with the previous clinical candidate, but much higher ligand efficiency,
better drug-like properties and initial SAR suggesting high optimization potential. Moreover, recent
breakthroughs in understanding the neuroimmune functional role of AT2R in neuropathic pain helped us to
establish a set of cell-based functional assays, lack of which hampered previous development efforts. Using
these platforms, we plan to establish comprehensive SAR for our main and backup lead series, and develop a
screening funnel in the 1-year UG3 phase of the project. In close collaboration with the BPN steering committee,
consultants and contractors, this screening funnel will then be employed in UH3 phase to optimize the lead
potency, selectivity, ADMET and PK properties relevant for AT2R lead development, including peripheral
restriction that precludes CNS side effects. This would allow selection of clinical development candidate for pre-
development, IND-enabling studies and preparation of IND targeting post-herpetic neuralgia.