RE:Tarveda TherapeuticsWe spoke about this company here before. Their first candidate PEN-866 with SN38 went through a dose escalation phase I. It is interesting to read the results. They claim to be able to determine tumor accumulation of the drug through tissue pharmacokinetic (I am not sure exactly what it means and how they can do that). On the efficacy front, out of 26 evaluable patients, 11 had stable disease at 8 weeks of which seven lasted 12-58 weeks. One partial respose (tumor shrinkage higher than 30%), and decreased target lesion size in six patients. So as we can see, nothing spectacular on the efficacy front. Patients were selected based on cancer type, not HSP90 expression. They have extended this trial to a phase IIa on multiple cancer types. They plan to enroll more than 300 patients.
It is hard to compare two very different drug conjugate/receptor concepts with two different cytotoxic drugs involved, and PEN-866 is not a PDC, it is a small molecule ligand conjugated to SN38. But we can see that efficacy results are modest in phase I, and Thera will not have stable diseases on many patients, because they treated a very limited number, and obviously not for as long as 58 weeks, not even close. All that being said, PEN-866 is in phase IIa even though it had so little efficacy data in phase I. But they claim to have proof of tumor accumulation of the drug, which is proof of concept.
https://ascopubs.org/doi/abs/10.1200/JCO.2020.38.15_suppl.3515