@myHC101I couldn't tell you exactly why PH left PTX's board, but...

@myHC101
I couldn't tell you exactly why PH left PTX's board, but it may have something to do with being thrown into the MD role in 2015 when then MD, Robert Crombie resigned "to focus on other business opportunities". That may have given him some coal-face exposure to the business which he may have wanted to step away from . But I'm sure PH is a very busy man and is a master of his own time, and so he can choose to spend it on projects that he feels will most benefit from his presence on the Board. So I'm going to hazard a guess that PH may have felt that PTX was in good hands with SYC at the helm and chose to look for his next venture.

In terms of why CHM (and not PTX) was set up to acquire CLTX and the CDH17 assets? It could be that PTX is already well down its path with its current pipeline and doesn't need a new asset. Each asset takes a long time to develop and is not cheap so expanding a pipeline too wide may mean you are going to be over stretched and not achieve the potential of any of your 'core' assets. If PTX are going to go to a registrational trial, expect their cash burn to increase exponentially for each trial they conduct... Kite and Juno were burning through approx. US$200m a year. Much larger businesses than PTX, but it puts into perspective the magnitude of funding required to get a drug into the US market.

But I also know that CLTX and CDH17 were bid on from a number of potential partners... PH said it himself they were lucky to be chosen to be the licensee. These teams of researchers have spent over a decade of their lives developing a product, which is essentially their 'baby' and won't just license it out to anyone.. and it's not all about the money, not at all. What is most important to them is that their 'baby' is given to a competent team who will give their 'baby' the attention and opportunity they feel it deserves to fulfil its potential.. that means they want to license it to a team they feel have the ability to get it to market (through the FDA) as well as ensuring that team is going to aggressively develop their asset.

So it could be that PH got his 'A team' together to hunt down high potential CAR-T's and felt he could only acquire these if he had an 'A team' that could convince the researchers their 'baby' would be given the best opportunity to reach its potential. If you look at the difference in the FDA experience between PTX and CHM, that may give you an idea of why PH chose to list a new company with this new management team.