CytomX lays off 40% of staff, questions future of Amgen-partnered T-cell engager

CytomX Therapeutics is shrinking its head count by 40% as the biotech regroups and looks at fresh ways to conserve cash.

In order to focus its resources on its lead antibody-drug conjugate (ADC) and an array of Big Pharma partnerships, CytomX is considering the future of the Amgen-partnered CX-904, the company said in a Jan. 6 press release. The biotech will continue an ongoing phase 1a trial that has been assessing the best dose for the EGFRxCD3-targeting T-cell engager, but it will now “prioritize escalation to higher dose levels," the company explained.

In the longer term, CytomX said it's considering whether to go ahead with previous plans to move into phase 1b “pending ongoing consideration of 2025 program resourcing."

An initial readout from the phase 1a trial last year demonstrated a favorable safety profile with no cytokine release syndrome—a potentially life-threatening toxicity that can occur after some cancer therapies—of any grade observed in the step-dosing cohort.

CytomX will also continue to investigate CX-801, an interferon alpha-2b cytokine being developed for metastatic melanoma that is being assessed in a phase 1 study as a monotherapy and in combination with Keytruda.

But the “top strategic objective” in the company’s remaining wholly owned pipeline is CX-2051, an ADC being evaluated in a phase 1 study for metastatic colorectal cancer (CRC). The drug is aimed at a “previously undruggable” CRC antigen called EpCAM (Epithelial Cell Adhesion Molecule), and includes the payload of a next-gen topoisomerase-1 inhibitor licensed from Immunogen. 

The aim is to “open a therapeutic window for this high potential target and deliver meaningful anti-cancer activity in solid tumors,” CytomX explained in yesterday’s release.

In a statement, the biotech’s CEO Sean McCarthy said the company has been “encouraged by our early clinical progress" and remains "on track to deliver initial phase 1a dose escalation data in the first half of 2025.”

Aside from Amgen, CytomX also has an array of ongoing collaborations with the likes of Astellas, Bristol Myers Squibb, Moderna and Regeneron. These partnerships “remain a strategic priority given their long-term value creation potential and the increasing relevance of masked, conditionally active therapeutics in the field of oncology research and development,” the biotech explained.

This means the planned layoffs will primarily affect “areas supporting non-partnered early research, and general and administrative functions,” CytomX said.

The redundancies are expected to be complete by the end of March, helping the biotech extend the $117.6 million it ended September 2024 with into the second quarter of 2026.

“As we enter 2025, we have taken the difficult decision to streamline our organization and resources towards top priorities and we look forward to sharing progress from our pipeline throughout the year," McCarthy said.

CytomX’s staffers aren't strangers to layoffs. Back in 2022, the company made a similar 40% cut to its workforce after its lead CD166-directed ADC failed in a phase 3 trial in triple-negative breast cancer.

The biotech’s plans took another hit last year when BMS walked away from a checkpoint inhibitor pact assessing a potential successor to Yervoy, wiping $300 million off the value of the companies’ ongoing alliance.