CytomX Therapeutics : First Quarter Earnings Update - May 8, 2024

1. Multi-ModalityProbody® Therapeutic Pipeline to Address Major Unmet Needs in Oncology

First Quarter Earnings Update

May 8, 2024

© 2024 CytomX Therapeutics, Inc.

Forward-Looking Statements

This presentation may contain projections and other forward-looking statements regarding future events. All statements other than statements of historical facts contained in this presentation, including statements regarding our future financial condition, technology platform, development strategy, prospective products, preclinical and clinical pipeline and milestones, regulatory objectives, expected payments from and outcomes of collaborations, and likelihood of success, are forward-looking statements. Such statements are predictions only and involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. These risks and uncertainties include, among others, the costs, timing and results of preclinical studies and clinical trials and other development activities; uncertainties inherent in the initiation and enrollment of clinical trials; uncertainties on the availability and timing of data from clinical trials; the risk that initial clinical data may not reflect later clinical trial results; the unpredictability of the duration and results of regulatory review; the uncertainty of market acceptance for approved products and innovative therapeutic treatments; competition; the potential not to receive partnership milestone, profit sharing or royalty payments; the possible impairment of or inability to obtain intellectual property rights; possible safety or efficacy concerns with our drug candidates; and general business, financial and accounting risks and litigation. Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified and some of which are beyond our control, you should not rely on these forward-looking statements as predictions of future events. More information concerning us and such risks and uncertainties is available on our website and in our press releases and in our public filings with the U.S. Securities and Exchange Commission. We are providing this information as of its date and do not undertake any obligation to update or revise it, whether as a result of new information, future events or circumstances or otherwise. Additional information may be available in press releases or other public announcements and public filings made after the date of this presentation.

This presentation concerns products that have not yet been approved for marketing by the U.S. Food and Drug Administration (FDA). No representation is made as to their safety or effectiveness for the purposes for which they are being investigated/

2

Today's Speakers

3

Agenda

Q1 2024 Updates & T-Cell Engager Strategy

Dr. Sean McCarthy, D.Phil. - Chairman and CEO

CX-904 Phase 1a study - Initial Dose Escalation Data

Dr. Wayne Chu, M.D. - Chief Medical Officer

Next Steps & Concluding Remarks

Dr. Sean McCarthy, D.Phil. - Chairman and CEO

Q&A Session

4

Company Snapshot

Addressing Major Unmet Need in Oncology

PROBODY® Platform: Unique antibody masking strategy for tumor localization and enhancement of therapeutic index

Pipeline: >15 Probody programs in multiple therapeutic modalities; 3 clinical-stage molecules with retained commercial rights

Lead Programs: CX-904(EGFR-CD3),CX-2051 (EpCAM ADC), and CX-801(IFN-α2b)

Partners: Bristol Myers Squibb, Amgen, Astellas, Regeneron, Moderna

Financials: ~$150M cash balance as of Q1 2024 with cash runway to the end of 2025, excluding any potential milestones or new business development

Organization: ~120 employees; seasoned executive team with ~200 years of collective biotech experience; integrated R&D capabilities to support wholly-owned and collaboration programs

5

CytomX Product Design Strategy Leverages the PROBODY® Platform

Optimized selection of target, prodomain and effector function

6

CytomX is Executing to Plan and Entering a Data-Rich Period

2024 & 2025 Potential Milestones

7

PROBODY® T-Cell Engager Strategy

© 2024 CytomX Therapeutics, Inc.

CytomX PROBODY® T-cell Engagers are Designed to Address Key Limitations of Conventional TCEs in Solid Tumors

PROBODY® T-Cell Engagers

9

CX-904(EGFR-CD3) Builds on CytomX Scientific Leadership

Masking EGFR antibody therapeutics to widen therapeutic window

Proof-of-concept that masking can reduce EFGR on-target toxicities

Proof-of-concept for efficacy and

therapeutic window for masked EGFRxCD3

10