resTORbio Announces Phase 3 Human Trials


Last year, resTORbio announced the positive results of its phase 2b human trial, which targeted the aging immune system with an immune system-boosting drug. Now, the company has announced the news that its therapy is moving to a phase 3 study later this year after successful negotiation with the FDA.

Targeting the mTOR pathway of aging

resTORbio is a biopharmaceutical company that is developing therapies that directly target the aging processes in order to prevent or cure age-related diseases. Its primary candidate drug is RTB101, which targets part of the mTOR pathway, one of the pathways involved in aging.

mTOR, the mechanistic target of rapamycin, is composed of the TORC1 and TORC2 protein complexes. It senses amino acids and is associated with nutrient abundance. It is a kinase, which means that it adds phosphates to molecules. mTOR is a primary regulator of anabolic metabolism, the process of building new proteins and tissues.

In this way, how it works is similar to the insulin and insulin-like growth factor (IIS) pathway. At any given moment, the metabolism is either breaking down old parts (catabolism) or building new ones (anabolism). Both mTOR and the IIS are part of the anabolic side of metabolism.

Targeting TORC1 has been demonstrated to increase the lifespan of mice and other species as well as boost the function of the immune system, improve memory and mobility, reduce obesity, ameliorate heart failure, and delay the development of some age-related diseases. On the other hand, targeting the TORC2 complex is known to reduce animal lifespan and cause hyperlipidemia and hyperglycemia in animals and humans.

While some naturally occurring substances target both complexes, which can lead to harmful results, resTORbio wanted the ability to selectively target TORC1 but not TORC2. RTB101 was the result of its research, and this drug seems to have accomplished this goal.

Moving into phase 3 human trials

Working with the FDA, resTORbio has reached an agreement on the format for the phase 3 program, which will include two randomized, double-blinded, placebo-controlled phase 3 clinical trials.

The first trial is planned to begin in the southern hemisphere in the second quarter of 2019 and is expected to enroll approximately 1,000 participants. The second trial is planned to begin in the Northern Hemisphere in the fourth quarter of 2019 and is expected to enroll approximately 1,600 participants. Trial participants will be aged 65 or over, and the trial will exclude current smokers and people with chronic obstructive pulmonary disease (COPD).

The phase 3 studies build on the results of the phase 2/2b trials, in which RTB101 was shown to improve the immune systems of older people and reduce the occurrence of respiratory tract infections (RTIs). RTIs are a common reason that older people are hospitalized, and they can lead to various life-threatening complications, including elevating the risk of cardiovascular events.

The new program will assess if RTB101 reduces the occurrence of RTIs in patients versus placebo, and it will last 16 weeks. The company is confident that the results of this trial should support a new drug application (NDA), barring any safety concerns that arise during the study program.

The NDA application is one of the final regulatory steps that allows resTORbio to propose to the FDA that the sale and marketing of its drug should be approved in the United States. The study data, all the way from initial animal studies through phase 3 trials, are taken into account as part of this process. If successful, it would mean the drug is given the official green light by the FDA and will be available for use in healthcare.

The company anticipates that, pending the results of the phase 3 study, it will have high-quality data by mid-2020.


If the results of the previous phases are replicated again in the larger phase 3 program, there is every reason to expect that this drug will be given approval and be available in the next few years.

Having an effective drug that helps bolster the immune systems of older people during cold and flu season would be a great step forward for immunotherapies and another example of how directly targeting the aging processes to prevent age-related diseases is the next bold step for medicine.

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