CytomX Therapeutics, Inc. Q1 FY2024 earnings call

• CytomX is focused on oncology using the Probody therapeutic platform, with over 15 active programs including 3 clinical stage molecules. • Progress on CX-904 Phase I study: Positive initial dose escalation data, showing limited cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and manageable EGFR toxicities; confirmed partial responses in pancreatic cancer patients. • Updates on other programs: CX-2051 Phase I study first dose cohort cleared, anticipates data in H1 2025; CX-801 Phase I study initiation with Merck agreement for KEYTRUDA combination, anticipates data in 2025. • Collaborations: Earned $10M milestone from Astellas collaboration, working with partners like Bristol-Myers Squibb, Amgen, etc. • T-cell engager strategy: Masking strategy to reduce toxicities in normal tissues and enhance tumor localization by using unique peptides and protease cleanable substrates to improve the therapeutic window.

No detailed financial segment performance provided in the transcript; focus is on pipeline and clinical progress rather than revenue by product segments.

• Anticipate continued progress in 2025, including data from CX-2051 and CX-801 in 2025. • Plan to aggressively pursue the signal from CX-904 in pancreatic cancer and expand enrollment to other EGFR positive tumor types (e.g., lung, upper GI, head and neck cancers). • Intend to provide additional CX-904 update later in 2024.

• Inherent uncertainties in forward-looking statements related to clinical trial outcomes, regulatory approvals, and market acceptance. • Risks associated with toxicities and side effects in T-cell engager therapies, though masking strategy aims to mitigate some toxicities (e.g., CRS, ICANS).

Q: Can the masking benefit extend to other T-cell engagers and is pancreatic cancer special?

A: Sean believes the masking benefit can likely extend to other programs, noting 904 is a strong start. Pancreatic cancer is interesting as it's typically immunologically cold but CX-904 shows activity, while other tumor types are in early stages of study.

Q: Dose relationship and balance between efficacy and tolerability?

A: There's a dose response, and the safety profile allows for higher dosing. Phase Ib is likely to use step strategies to explore further dose and schedule options.

Q: EGFR-mediated toxicities and pancreatic cancer progression?

A: EGFR toxicities are manageable, with mostly Grade 1/2 rash. A pancreatic cancer patient's progression involved new lesions and growth of target lesions.

Q: Baseline characteristics predictive of response and duration of stable disease?

A: No clear patient characteristic predictors of response, but early data shows stable disease in some patients with varying durations, and pretreatment biopsies with high CD8-positive T cells were intriguing.