Preclinical resultsForget about the activity they saw in vitro on cancer cell lines and in vivo on nude mice grafted again with single cancer cell lines. It means almost nothing about the validity of the drug.
I made a quick search about Zoptarelin, the failed PDC from Atearna Zentaris. It failed on more than 300 patients in phase III on endometrial cancer in 2016. But I found a paper from 2020 where they were testing it in vitro on an uveal melanoma cell line overexpressing LHRH receptors. It was at an university in Hungary and they claim activity on gene expression and angiogenesis and so on in vitro. Their conclusion is that a PDC aiming at LHRH receptors should work. Sure, ask Aeterna Zentaris investors about that.
I really think there is something wrong with PDCs using simple unstable linkers and old cytotoxic drugs. It works in the lab, but not on real patients. The approved ADCs are using newer and more potent cytotoxic drugs, and bigger and more complex linkers. The only approved PDCs are the one using stable linker and very potent radioisotopes. Thera should be able to see that and correct course. Drop TH1902 and desing a new PDC that would not have the flaws TH1902 has.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6968782/