Vertex Pharmaceuticals (VRTX) said Tuesday that a phase 2b study of inaxaplin to treat patients with APOL1-mediated kidney disease showed a 42.7% protein reduction, and a 17.3% reduction in patients who also have type 2 diabetes.

The company said the drug showed a favorable safety profile with no drug-related serious adverse events reported. It said headaches were the most frequent side effect, which affected 7.3% of trial participants.

The company said the reduction was measured after 13 weeks of treatment. Vertex said it has finished enrolling patients in a larger Phase 2/3 trial of inaxaplin.

Shares of Vertex were up 2.2% pre-bell.