Rachel Humphrey, M.D., who joined CytomX Therapeutics as chief medical officer after heading immuno-oncology at AstraZeneca and Eli Lilly, has made her exit. Her tenure at the probody biotech ended Monday, according to a Securities and Exchange Commission filing filed that day.
CytomX gave no reason for Humphrey’s departure in the brief filing, saying only that “On August 19, 2019, it was determined that Rachel W. Humphrey, M.D., senior vice president and chief medical officer of CytomX Therapeutics, (the “Company”), would leave her position and employment with the Company, effective August 19, 2019.”
A doctor by training, Humphrey started her biopharma career at Bayer, overseeing the development of the bladder cancer drug Nexavar before moving on to Bristol-Myers Squibb, where she worked on the immuno-oncology med Yervoy. She signed on as chief medical officer at Mirati before heading to AstraZeneca and then Eli Lilly for comparatively short stints to lead those companies’ immuno-oncology efforts. wound up at South San Francisco-based CytomX in 2015, five months after she joined the company’s board.
Her departure comes six months after CytomX partner Bristol-Myers Squibb abandoned three discovery-stage programs from a $3.6 billion biobucks deal struck in 2017. And that news came after a different Big Pharma pulled out from a pact inked in 2013 that netted CytomX $25 million at the time, but could have been worth up to $635 million.
Pfizer officially ended that partnership after five years, but it had been gradually pulling back from it. Pfizer was to pick up to four probody-drug conjugate targets under the deal, but decided not to pull the trigger on a fourth option. It returned the rights to an EGFR program and then culled the second and third partnered programs in the first quarter of 2018.
That said, CytomX still other partners, notably Amgen and AbbVie. The duo is working on a program against CD71 and announced last month they have picked out a second target, triggering a $10 million milestone payment.
CytomX's work is based on probodies and probody-drug conjugates that deliver a payload of highly toxic agents directly to cancer cells. The probody is designed to stay inactive in healthy tissue and then arm itself once it arrives at a tumor, activated by proteases in the disease tissue after binding only to antigens found in that tissue