Excitotoxicity in the Motor System
Using advanced stem cell technologies, the founders of QurAlis, Professors Kevin Eggan and Clifford Woolf together with Dr. Brian Wainger worked together with ALS patients and reprogrammed some of their skin cells into stem cells. Next, these stem cells were made into the same type of motor neurons that are degenerating in the ALS patients body. This allows us to study the motor neurons in a laboratory setting. A careful examination of these motor neurons showed that they exhibit a similar hyperexcitability as is found in ALS patients. Through careful measurements, Dr. Wainger then identified a decreased activity of a certain potassium channel, the Kv7.2/7.3 channel. This decreased activity of Kv7.2/7.3 made ALS motor neurons hyperexcitable compared to control neurons where the ALS gene mutation in the SOD1 gene have been removed from the DNA. An already approved epilepsy medicine called Ezogabine also known as retigabine was able to restore the activity of the Kv7.2/7.3 channel and reduced the hyperactivity of the motor neurons to normal levels. The medicine was also able to increase the survival of the motor neurons with ALS mutations. Ezogabine/retigabine is now tested in a Phase 2a biomarker trial to confirm that it reduces the hyperactive motor system of ALS patients. If so, it is also possible that it prolongs ALS patient survival.
QurAlis is now developing an even better Kv7.2/7.3 drug that will have less side effects and is more potent for motor neurons specifically. We will do this using the new and very potent molecules that we have identified together with the use of chemistry techniques and our advanced stem cell technology platform and the Q-State optopatch platform to make sure the drug works well for ALS patients specifically.
Geevasinga, N., et al., Pathophysiological and diagnostic implications of cortical dysfunction in ALS. Nat Rev Neurol, 2016. 12(11): p. 651-661.
Restoration of the TBK1 autophagy pathways
Through large DNA sequencing efforts, the scientific community has now been able to identify almost 30 different genes that can cause ALS. These genes code for proteins which are targets for the development of precision medicine for ALS. Interestingly, a number of these genes have pointed to key cellular processes which appear to be causal to the disease when disrupted such as the cellular waste clearance pathways, which are also called the autophagy and mitophagy pathways. It is through these waste clearance pathways that toxic protein buildups are removed from cells and through which old broken cellular components responsible for energy production are recycled. At this moment, 4 different genes have been identified in these pathways that cause the development of ALS: TBK1, Optineurin, p62 and Ubiquilin-2. Interestingly, these genes can also cause the development of frontotemporal dementia (FTD) and many ALS patients with mutations in these genes develop both ALS and FTD.
TBK1, a serine/threonine-protein kinase is a key regulator of the waste clearance (autophagy) pathways. TBK1 mutations are found 1-3% of all ALS and FTD patients. TBK1 directly regulates the ALS genes optineurin and P62 through phosphorylation. Mutations in TBK1 lead to a reduced function of the protein which means that the waste clearance pathways are only working at half speed. QurAlis has identified an enzyme which normally inhibits the autophagy pathways. An inhibitor of this enzyme will bring the waste clearance pathways back to normal functioning levels and QurAlis is developing a medicine to do just that. Through mouse studies we know that such a medicine is safe, and the study of human post mortem tissue and stem cell models have made clear that it will target the motor neurons and microglia which are affected in patients with ALS.
QurAlis is following a structure based drug design approach, which means that we use a crystallized form of the target protein to guide the chemistry processes to make a “smart” molecule which is specific and potent and doesn’t have problematic side effects. Last, QurAlis uses stem cells from ALS patients to make sure that our developed molecule actually works before turning it into a medicine.