Pyxis Oncology (PYXS) Status Update summary

Clinical Program Highlights

• PYX-201, a novel antibody-drug conjugate (ADC), demonstrated strong stability, targeted delivery, and a favorable safety profile in 80 heavily pretreated patients across multiple tumor types, with a focus on head and neck cancer.

• The ADC targets extracellular domain B (EDB), a splice variant of fibronectin highly expressed in tumors but minimally in normal tissue, reducing off-target toxicity.

• Dose escalation identified 3.6–5.4 mg/kg as the optimal range, with a 1% overall discontinuation rate and no grade 5 treatment-related adverse events; most side effects were mild and manageable.

• Efficacy signals were observed in six tumor types, with head and neck cancer showing a 50% objective response rate (including a complete response) and durable disease control in a population with a median of four prior therapies.

• Early promising responses were also seen in lung, ovarian, HR-positive breast, triple-negative breast, and sarcoma, with ongoing exploration in these indications.

Mechanism of Action and Innovation

• PYX-201 is a first-in-concept ADC targeting EDB+FN, a non-cellular extracellular matrix component overexpressed in solid tumors.

• The mechanism involves extracellular payload release, enabling direct tumor killing, bystander effect, and immunogenic cell death.

• Site-specific conjugation and optimized linker/payload chemistry result in high stability, predictable pharmacokinetics, and reduced off-target effects, outperforming comparators like PADCEV.

• Demonstrates lower free payload in circulation and longer half-life compared to traditional ADCs.

• The unique extracellular targeting allows for broad tumor applicability and potential synergy with immuno-oncology agents and other ADCs with non-overlapping toxicities.

Clinical Trial Design and Patient Population

• Phase 1 dose escalation study enrolled 80 patients with 10 solid tumor types across 18 global sites.

• No biomarker selection; patients were heavily pretreated with a median of 4 prior therapy lines.

• Doses ranged from 0.3 to 8 mg/kg, with 3.6–5.4 mg/kg identified as the effective range.

• 52% of patients were recruited into the 5.4 mg/kg dose group.

• Median age was 65 years, and 71% had ECOG performance status 1.