Famously known as the powerhouse of the cell, the mitochondria is responsible for generating most of the energy that fuels cellular reactions. That’s why when this organelle does not function properly, it leads to a number of diseases. Various biotechs are now working on treatments to restore mitochondrial function to fight these diseases.
One of them is Swiss biopharma Vandria. The company targets the mitochondria by inducing a process known as mitophagy. This refers to the natural breakdown of the mitochondria to maintain cell health. While previous methods to induce this function proved problematic as it caused “significant mitochondrial dysfunction and overall cellular stress,” Pénélope Andreux, chief scientific officer (CSO) of Vandria, explained that newer approaches such as employing ‘mitophagy inducers’ to do the job are safer.
“There are various methods to induce mitophagy,” said Andreux. “More recent approaches focus on identifying mitophagy inducers that activate the process only in the presence of mitochondrial damage. This means that these compounds, on their own, do not disrupt the mitochondrial membrane potential or the mitochondrial respiratory chain, but instead restore mitophagic flux when mitochondria are compromised.”
“You really want the mitochondria to keep their integrity, to avoid exploding and releasing this mitochondrial DNA because it will be recognized by the immune system as a danger signal.”
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Mitochondrial dysfunction: “a danger signal”
But first, why the mitochondria? As the mitochondria is pivotal to how a cell operates, Andreux likens its importance to a function as vital as breathing. The oxygen that we breathe in goes into the blood and into the cells, particularly the mitochondria.
“The reason why we need oxygen, why we have the heart that is pumping all the time is that we need to have a good blood composition that is able to carry oxygen and bring it inside the tissue. The last receiver of oxygen is the mitochondria. And as you know, if you don’t have enough oxygen, you die. So, that shows you the importance of mitochondria; it is just what keeps us alive,” said Andreux.
So, if the mitochondria does not work properly or if its performance wanes, it could lead to age-related diseases including neurodegeneration.
“Our mitochondrial function is declining with age, and that’s something that we can actually measure,” said Andreux. “We need to really keep them up to speed, and in good shape.”
An example of this decline in performance is exhibited in the COVID-19 virus’ link to mitochondrial dysfunction. A study conducted by the Children’s Hospital of Philadelphia (CHOP) and the COVID-19 International Research Team last year, showed that the pathogen suppressed genes in the mitochondria, which was what actually caused brain fog, fatigue, and cardiovascular issues in hamsters that tested positive. This implies that any sort of disruption to the DNA in the mitochondria can have serious effects on how a disease manifests.
Moreover, the mitochondria is an integral part of the immune system. Mitochondria contain circular DNA, and when this DNA leaves the cell, it is recognized as a danger signal by the immune system.
“You really want the mitochondria to keep their integrity, to avoid exploding and releasing this mitochondrial DNA because it will be recognized by the immune system as a danger signal,” added Andreux.
When there is chronic inflammation, it is often linked to mitochondrial dysfunction, which further over-stimulates the immune system. This then causes the release of pro-inflammatory cytokine cells which further damages the tissue leading to more mtDNA being released.
“It’s a vicious cycle,” remarked Andreux.
Vandria’s pipeline: novel treatments targeting mitochondrial dysfunction for cognitive diseases
Targeting this mitochondrial dysfunction can bring down inflammation, which is what biotechs like Vandria specialize in.
“We have discovered a novel mechanism of action and are developing first-in-class mitophagy inducers with a unique dual mode of action with short-term benefit in cognitive function and long-term effects on neuroprotection and neuro-inflammation,” said Andreux.
The drugs in its preclinical pipeline induce mitophagy and activate a pathway known as the PINK1/Parkin pathway that governs mitochondrial quality control. They bind to an undisclosed, novel target. The lead candidate VNA-318 is a brain-penetrant molecule that will head to the clinic in the next few weeks. It has been tested in preclinical models of Alzheimer’s disease, Parkinson’s disease, and mild cognitive impairment where it was found to improve mitochondrial function, reduce neuroinflammation, and thereby have a neuroprotective effect on the different models of neurodegenerative diseases.
Another one of Vandria’s candidates is designed to treat a progressive muscular disease called sporadic inclusion body myositis. Also known as the ‘Alzheimer’s of the muscle’ owing to the buildup of the same proteins that are hallmarks of Alzheimer’s in muscles, the root cause of the disease is mitochondrial dysfunction and inflammation. The biotech’s VNA-052 is currently undergoing Investigational New Drug (IND)-enabling studies.
NRG’s small molecules: novel approach to restore mitochondrial function
While inducing mitophagy might be the road taken by Vandria, there are other ways to reinstate mitochondrial function. For instance, British biotech NRG Therapeutics has discovered a new class of small molecule drugs that protect mitochondria and in turn, treat diseases like Parkinson’s disease and the rare, fatal muscle disease amyotrophic lateral sclerosis (ALS).
These drugs do so by targeting a channel that resides on the inner mitochondrial membrane called mPTP. Activating the mPTP can trigger mitochondria collapse and the loss of its ability to produce energy. Many drugs that target the mPTP do not cross the blood-brain barrier, which is where NRG’s drugs differ. Its inhibitor drugs prevent mitochondrial dysfunction caused by misfolded TDP-43 and α-synuclein, the two proteins that cause the degeneration of neurons in ALS and Parkinson’s, explained Neil Miller, chief executive officer (CEO) and co-founder of NRG.
“Mitochondrial dysfunction is a common underlying pathology in many degenerative diseases and there is a substantial body of preclinical data available, which demonstrates that inhibition of the mPTP in the brain prevents neuronal cell death, reduces neuroinflammation and extends survival in animals,” said Miller.
In ALS, the abnormal TDP-43 causes the mitochondrial DNA to exit the mitochondria via the mPTP, which as established, is dangerous. NRG’s preclinical candidate is designed to stop the mPTP from allowing the DNA to leave. Whereas, in the case of Parkinson’s, the hallmark proteins known as α-synucleins localize to the mPTP. So, inhibiting the mPTP, can halt cell death and delay the progression of the neurodegenerative condition, which is what NRG’s second candidate does.
These investigational drugs have been found to prevent the death of brain cells and to reduce neuroinflammation in animal models of ALS and Parkinson’s.
As the biotech’s ALS drug gears up for the clinic next year, Miller said: “If successful in clinical trials, NRG’s therapeutics would be the first disease-modifying medicine to prevent or delay disease progression in sporadic ALS and in Parkinson’s where current treatments only provide management of disease symptoms.”
Mitochondrial disease treatments: a diverse space
However, hunting for molecules that address mitochondrial function – previously slammed for hosting undruggable targets – is not easy. These include targets such as E3 ligases, transcription factors, and membrane receptors, that affect the mitochondria and have been difficult to drug in the past. But Japanese pharmaceutical Astellas’ swooped in two years ago, employing its acquired company Mitobridge to discover small molecules that address these undruggable targets along with U.S.-based Generian Pharmaceuticals in a $180 million deal. This added to the multinational’s roster of mitochondria-targeted therapies – like the £12 million ($15.90 million) buyout of mitophagy-focused Nanna Therapeutics and its alliance with Minovia Therapeutics, which has come up with a way to enrich immature cells with healthy mitochondria.
What makes mitochondria-focused therapies so versatile is that there are different ways to go about it. Be it Vandria’s approach of targeting the PINK1 pathway – also done by AbbVie-bought Mitokinin – to induce mitophagy, NRG’s therapies inhibiting the mPTP, or even a company like Primera Therapeutics engaging in gene editing of mitochondrial DNA, the field is burgeoning different kinds of R&D programs. And while many of these biotechs zero in on degenerative diseases, startups like U.K.-based MitoRx have shown that even metabolic diseases like obesity could potentially be treated, offering a non-GLP1 option to patients in the future.
As more first-in-class drugs get tested in the clinic, Andreux’s Vandria will have its lead candidate there soon.
“We are very encouraged by our toxicology data, which are very clean, so we could see a very safe profile in the preclinical models…We are confident that it will go well with humans,” said Andreux. “It’s all very exciting.”
Technologies related to the mitochondria
- Strategies to Ameliorate Mitochondrial Dysfunction in Disease – Whitehead Institute
- Mouse Model for Mitochondrial Diseases – Max Planck Institute
- Mitochondrial Targeting Compounds for the Treatment of Associated Diseases – University of Michigan