- Idelalisib plus obinutuzumab shows clinical activity with an objective response rate of 90% in patients with relapsed/refractory Waldenstrom’s macroglobulinemia.
Why this matters
- Waldenstrom’s macroglobulinemia continues to have poor outcomes despite recent FDA approval of tyrosine kinase inhibitor ibrutinib.
- Idelalisib, a phosphatidylinositol-3-kinase pathway inhibitor, recently demonstrated an objective response rate of 80%.
- This is the first study to evaluate a chemotherapy-free novel combination of idelalisib and obinutuzumab.
- Interim analysis of phase 2 Filo trial.
- 49 patients with relapsed/refractory Waldenstrom’s macroglobulinemia received idelalisib 150 mg twice daily and obinutuzumab titrated to 1000 mg for a total of 6 28-day cycles during the induction phase.
- Idelalisib was continued during the maintenance phase for up to 2 years.
- Funding: Janssen.
- Median follow-up was 18.3 (range, 14.9-23) months.
- The overall response rate was 90% and the major response rate was 76% (very good partial response, 8%; partial response, 68%; minimal response, 14%).
- Median PFS was 25.2 months.
- 1-year and 2-year OS was 98% (95% CI, 94%-100%) and 85% (95% CI, 69%-100%), respectively.
- Median duration of response was 21.8 months.
- 35 patients experienced ≥1 grade ≥3 adverse events or serious adverse events.
- Most frequent adverse events were hepatotoxicity, diarrhea, infections, skin disease, neutropenia, anemia, and thrombopenia.
- The study is ongoing in 29 patients who entered the maintenance phase.
- No comparator.
- The findings need confirmation in the final analysis.