How Jagabandhu Das made dasatinib possible
In my story on how drugs get their generic names for this week’s issue of C&EN, I briefly discussed how the chronic myelogenous leukemia medication Sprycel (dasatinib), mentioned in this Haystack post by SeeArrOh, ended up being named after Bristol-Myers Squibb research fellow Jagabandhu Das. Even though Das, or Jag, as his coworkers call him, didn’t discover the molecule that bears his name, the program leader for Das’s team, Joel Barrish, says dasatinib wouldn’t have existed without him.
So how’d Das make a difference? About one and a half years into the search for a kinase inhibitor that might be able to treat chronic myelogenous leukemia, “we were hitting a wall,” Barrish, today vice-president of medicinal chemistry at BMS, recalls. “We couldn’t get past a certain level of potency.”
Early on, the team’s work suggested that a 4′-methyl thiazole was critical for potency. Replace the methyl with a hydrogen, and potency went out the window. But Das challenged that dogma, Barrish says. He thought the compound series had evolved to the point where it would be a good idea to go back and test those early assumptions. His hunch paid off– in the new, later kinase inhibitor series, it turned out that removing the methyl group from the thiazole actually boosted potency. Thanks in large part to that discovery, the team eventually was able to make kinase inhibitors with ten thousand fold higher activity.
“Jag didn’t stop there,” Barrish says. After debunking the methyl dogma, Das found a way to replace an undesirable urea moiety in the team’s inhibitors with a pyrimidine group, which improved the inhibitors’ physical properties. With help from Das’s two insights combined, eventually BMS’s team came up with the molecule that became dasatinib (J. Med. Chem., DOI: 10.1021/jm060727j).
Generic naming requirements are extensive, but the committees involved in the naming process are willing to use inventors’ names as long as they fit the criteria.
But sometimes, Barrish says, “there’s luck involved in who makes the final compound.” In the dasatinib story, though, it was clear that Das’s discoveries were the keys to success.
When dasatinib was in clinical trials and it came time to put forward a set of possible generic names for consideration, Barrish didn’t have to think too hard about who was most responsible for his team’s success. “It was very clear in my mind that it was Jag,” he says. So he added dasatinib to the list.
“I admit, it was one of those things you do and you kind of forget about it, thinking, ‘oh, they’ll pick something else’,” Barrish says. When dasatinib ended up being the name of choice, he says, it made the entire team feel good. “And obviously, Jag was quite pleased with it.”