CytomX Therapeutics (CTMX) Morgan Stanley 24th Annual Global Healthcare Conference summary

Technology and clinical program overview

• Developed masked biologics to limit off-tumor toxicity and enable targeting of previously undruggable cancer antigens.

• Lead programs include an ADC for colorectal cancer (CRC) targeting EpCAM and a masked cytokine for melanoma.

• ADC design leverages a Topo I payload, benchmarked to ENHERTU, to maximize efficacy in CRC.

• Masking technology aims to create a therapeutic window for targets with high normal tissue expression.

Clinical data and safety management

• Phase I data in late-line CRC show response rates of 20%-30% and PFS of 6-7 months, outperforming current benchmarks.

• GI toxicity, especially grade 3 diarrhea, was managed by dual prophylaxis and adjusted dosing, reducing rates from 30% to 10%.

• Adjusted ideal body weight dosing implemented to reduce exposure outliers and improve tolerability.

• Ongoing monitoring and further data expected later this year to confirm safety and efficacy.

Development strategy and regulatory plans

• Dose optimization and FDA discussions (Project Optimus) are ongoing to finalize registrational study design.

• Initial registrational study likely to be a randomized monotherapy trial in late-line CRC with overall survival as the endpoint.

• Combination studies with bevacizumab and 5-FU are underway to potentially move into earlier lines of therapy.

• Initial data from combination studies expected in the first half of 2027.