This is subscriber-walled, but the full article is available here:

https://web.archive.org/web/20240909093450/https://www.statn...

The key reason Pfizer passed was that executives didn't think patients would accept a new therapy that required injection to administer:

Despite our emerging results, the Pfizer executives in charge of research and external alliances told us the company did not want to develop a new diabetes therapy that required injection, a space held exclusively by insulin since 1922. They gave us a year to find a way to deliver GLP-1 via transnasal, transcutaneous, or oral administration. Effective delivery by any of these approaches would have been great, but we knew success was unlikely in the year they gave us. Our effort was predictably unsuccessful, and after four years, Pfizer terminated our agreement as permitted under the alliance contract.

The first commercial GLP-1 receptor agonist, Exenatide, went to market as an injectable medication in 2005 [1]. Orally delivered GLP-1 medications didn't come to market until 2019 when orally dosed semaglutide was approved as Rybelsus [2].

Now that injected GLP-1 drugs are among the most-prescribed drugs in America, I wonder if drug company executives are going to be more receptive to drug candidates that require injections. There are a lot of molecules (especially peptides) that are degraded by the digestive system; maybe people will be more willing to inject medications when so many have started self-injecting for GLP-1 drugs or know someone who has.

[1] https://en.wikipedia.org/wiki/Exenatide

[2] https://en.wikipedia.org/wiki/Semaglutide#Legal_status