From what I saw (and the presentation is publicly available), they were able to show that the neoantigen based vaccine induced detectable immune responses in a large number of patients against the target neoantigens.
Nivolumab alone was not able to induce the same immunity against these antigens, so in principle they have shown it to be working. The efficacy data show that they got responses in the combo arm of nivo plus the vaccine, but it's not at all clear whether it was an improvement in terms of efficacy over nivo alone. Generously, it looks like the response rates were a little better in the melanoma cohort than historical nivo alone (something like 40% for nivo aone and 50% in this study with the combo).
But I would caution against drawing a firm conclusion, given the small-time nature of this study. Overall, the efficacy wasn't mindblowing for a technique with as much hype as neoantigen-based immunotherapy. So it looks like it will have to take a similar path to other drugs, and the hype is set to cool off a bit, I'd wager.
By no means is it a negative trial, either. It's a solid phase 1 that supports further investigation, but it doesn't give a very clear signal that the lights are all green for NTGN.
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