Parabilis Medicines (PBLS) Investor update summary

Phase 1/2 efficacy

• At the June 22, 2026 cutoff, 32-week landmark ORR was 72.2% (13/18) and 24-week ORR was 61.9% (13/21) among response-evaluable patients starting at ≥450 mg.

• Disease control was 100% among 46 response-evaluable patients starting at ≥450 mg, with no disease progression reported.

• Responses were dose-dependent, deepened over time, and occurred regardless of prior GSI exposure or CTNNB1 or APC mutation status; all partial responses with opportunity for confirmation were confirmed.

• The longest-treated patient in the ≥450 mg cohort had received treatment for nearly two years; no evidence of resistance was observed.

Safety and tolerability

• Across 76 treated patients, treatment-related adverse events were predominantly low grade, and no patients discontinued treatment due to TRAEs.

• Fatigue, alopecia and nausea were common at selected Phase 3 doses; maintenance-dose side effects were less frequent and less severe than during induction.

• No high-grade skin or gastrointestinal toxicities or ovarian toxicity were reported.

Phase 3 development

• Selected regimen: 450 mg weekly induction for four months, followed by 300 mg every two weeks for maintenance; dose selection was informed by randomized optimization arms.

• FDA alignment covers a placebo-controlled, two-arm design, pre- and post-GSI patients, and PFS as the primary endpoint.

• PEDESTAL plans to randomize 148 patients 1:1; eligible patients have active recurrent or refractory desmoid tumors with ≥20% tumor growth in the prior 12 months.

• Secondary endpoints include ORR, MRI tumor volumetrics, duration and time to response, disease control and patient-reported outcomes; placebo-arm participants may cross over after progression.

• Trial initiation is planned for H1 2027, with topline data projected for 2029; approximately 100 Phase 1/2 desmoid patients are expected to continue treatment and follow-up through approval.