LC states that: "It’s particularly gratifying to have followed a...

LC states that: "It’s particularly gratifying to have followed a patient in the trial for over 18 months where their tumour burden has been reduced to zero. For such a late-stage patient, having a chemo-free alternative could mean a very real difference to their quality of life, she added”.

So we know that they are counting this patient in the trial still, and we know this person would be 1 of the 3 remaining on the trial. As for the other 2, well we don't know exactly they haven't told us, I would assume that these two would have had SD at least at some point.
It could be the two SD on the 50μg dose or it could be the two who achieve SD at 100μg or even the 1 who achieve PR (or some combination).

With regards to your second point, this data is a snapshot of time and accurate at a given point in time. It could be that antibody production dipped after a certain number of weeks as shown in the graph below, and then their disease progressed after SD or PR. But at some point the patient being treated with PD1-Vaxx had a proven health benefit and it was recorded.

It's important to mention, that despite producing antibodies to fight the cancer, their immune systems are under severe pressure and constant attack. These patients are severely compromised and would be suffering from organ failure or other ailments. The fight wages on.