Boston biotech resTORbio has pocketed another $40 million from a second-round financing that it hopes gives it enough cash to move its lead candidate for respiratory tract infections in elderly patients into phase 3.

The latest round brings the total raised by the company—which was formed earlier this year by PureTech Health to take the lead on two Novartis-developed compounds for age-related deterioration of the immune system—to $65 million.

The new funding tranche will be used to push lead candidate RTB101 through a phase 2b trial and, if the results are positive, into a pivotal phase 3 program, according to resTORbio’s CEO Chen Schor, who notes that it will also allow the company to expand the program with a phase 2 trial in a second indication.

RTB101 is one of two orally-active TORC1 (rapamycin complex 1) inhibitors bundled into resTORbio and has been shown to enhance immune function in elderly patients in a phase 2 trial carried out by Novartis, which has a minority stake in the company.  

Novartis pioneered this mechanism with its Afinitor (everolimus) mTOR inhibitor product for cancer, which made $775 million in sales last year, mainly from use in breast cancer. mTOR signalling occurs through two complexes—TORC1 and TORC2—and blocking the former seems to be linked to beneficial effects on aging-related diseases. TORC2 inhibition on the other hand seems to cause adverse events, including hyperglycemia and raised cholesterol.

After finding preliminary evidence that TORC1 inhibitors could have potential in diseases of aging decided that its follow-up compounds would be more efficiently developed by a specialist company.

RTB101 is being tested alone and in combination with everolimus in resTORbio’s phase 2 trial, which was advanced into the phase 2b stage last week on the recommendation of its data advisory committee and is expected to report results in the second half of 2018, according to Schor.

It is intended to show that the drugs can reduce the percentage of elderly patients who develop respiratory infections over the 16-week study period.

“We believe our approach may provide an opportunity to address multiple aging-related diseases beyond our initial indication for reducing the incidence of RTIs in the elderly,” he said. resTORbio has suggested its second clinical target will be aging related organ failure or “autophagy-related diseases” a broad category which could include aging-related heart, liver or central nervous system disorders.

Along with OrbiMed, the series B backers include Fidelity Management & Research Company, Rock Springs Capital, Quan Capital and Nest Bio. OrbiMed partner Jonathan Silverstein has now joined resTORbio’s board of directors.