It's an important finding if the data they are seeing is...

It's an important finding if the data they are seeing is suggesting their proposed mechanism of action is indeed holding up.

Why exactly CLTX binds so well to GBM and other solid cancers has not been clinically established, though studies thus far point to MMP-2, the exact relationship is not yet known.

The patients accepted into this trial must have 20% or more MMP2+ expression in the GBM being targeted, which may seem low but that is about how much the IL13Rα2 CAR T used by City of Hope on Richard Grady has as well. It appears that so long as the CAR T kicks starts the immune response, the recruited cells not only target the 20%+ cells that have the antigen/receptor on its surface.. but the heightened level of T cells, macrophages and NK cells are able to destroy most non-expressing tumor cells as well.

So what we may see through the phase 1 trial (though on limited data / confidence) is whether or not a certain threshold of MMP2+ is required for a patient to respond to the treatment, and if a higher % correlates with a better response.. or if 20%+ is an appropriate criteria for the phase 2 study.