After the closing bell on Monday, G1 Therapeutics (GTHX -1.68%) announced that it plans to file for regulatory approval of trilaciclib, an agent to protect bone marrow from the damage caused by chemotherapy. In response, the company's shares skyrocketed, and were up 16% as of 3:15 p.m. EDT Tuesday.
Trilaciclib aims to reduce the risks to bone marrow production of white blood and red blood cells and platelets, which are important to preventing infection and maintaining energy levels.
In December, G1 Therapeutics reported results from a mid-stage study showing an overall response rate of 13.3% in second-line and third-line small cell lung cancer patients given trilaciclib and topotecan, a chemotherapy. The response rate was lower than chemotherapy alone, but the doublet did reduce the rate of severe (grade 4) neutropenia, a depletion of white blood cells.
In November, it delivered results from a study pairing trilaciclib with Roche Holdings' (RHHBY 2.31%) Tecentriq and chemotherapy in first-line small cell lung cancer, showing that the combination outperformed Tecentriq and chemotherapy alone. The trilaciclib arm had lower rates of neutropenia, anemia, and thrombocytopenia while producing similar overall response and progression-free survival rates to Tecentriq and chemoptherapy alone.
These findings were good enough for the company to emerge from its post-phase 2 meeting with the FDA encouraged. It plans to have a new drug application (NDA) pre-meeting with the FDA regarding trilaciclib's use in small cell lung cancer cases later this year, with an official NDA filing thereafter. After that, it also plans to file for European approval.
Chemotherapy damage to bone marrow can require doctors to change dosing and delay treatment in ways that can reduce the odds of positive outcomes. Therefore, trilaciclib's ability to protect bone marrow could make it a favored therapy for patients with small cell lung cancer -- a particularly tough cancer with historical five-year survival rates of 30% or less.
However, we're still a while away from an actual NDA filing, and even if the FDA grants a priority review, it will be six months or longer after that before the agency weighs in with its decision. Furthermore, there's no guarantee that doctors will incorporate trilaciclib into standard care if it is approved. A lot of questions remain for this company, so investors might want to wait and see what G1 Therapeutics says later this year about its pre-NDA meeting.