The regulators agreed to the changed SAP while the company was still blinded. Progressive free survival is a surrogate to overall survival and since an immunotherapy like DCVax can induce what doctors call pseudo-progression on scans (looks like cancer progression but is really the immune system attacking the cancer and causing swelling) it makes sense that they changed the primary endpoint to overall survival.
It’s explained in the JAMA article so your fear is unfounded and it makes it sound like you haven’t read up on what the company is doing.
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