Due Diligence on the short case for VBLT and my response: Part three.
On the rGBM....
This tweet looked at the phase II rGBM data. '1st 24 pats got bev only, next 22 combo. Biases due to sequence + open label, led to more doses in combo cohort? 2/2' Many similar tweets in the same vein.... i.e. the primary endpoint was changed from progression free survival to overall survival, many scoffed at the feverish versus non-feverish responses(this theme was made with ovarian as well) and the dubious comparator arm that is historical controls.
My response, yes the trial was amended to allow additional dosages of VB-111 with avastin on progression. The company went to the FDA and got the protocol amended because they believed that the mechanism of action of VB-111 might produce an initial pseudo progression on MRI that might just be a result of VB-111. That was there argument, the FDA allowed a protocol amendment and the next 22 patients got VB-111 along with Avastin on progression. But how can you explain 15 months overall survival with the combo arm? Avastin? Some fluke? Radical changes/improvement in the care of rGBM, some imbalance of the limited exposure versus continuous exposure cohorts? Other than fluke, the other explanations don't make much sense to me. Now, you can argue(and I have), that there may be some sort of synergy b/w avastin with VB-111 in tandem that may be the key, but hat is another argument.
Then there's this tweet.
and discussion.
But my response was this is from a SNO presentation in late '14. Note the censoring of the data to the left of the median, but by the SNO presentation in '15 and in the '15 final data presentations, the data was finally mature, and no more significant censoring. That's my response.
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