Worth noting that immunotherapy responses can take a really long time to manifest.
For example, in 0265 it took from July 2015 to May 2016 for the complete response to be confirmed radiologically. According to the ASCO 2014 study design poster, patients were followed every 3 months, so it's unlikely that they just happened to miss the complete response in that patient.
No saying, though, that NEO will behave the same way. But this is the only line of evidence we'd have to draw on regarding time to response, assuming there is one.