Pirtobrutinib in R/R follicular lymphoma: BRUIN trial

The multicenter phase I/II BRUIN trial (NCT03740529) evaluated pirtobrutinib, a non-covalent (reversible) Bruton tyrosine kinase inhibitor (BTKi), monotherapy in patients with relapsed/refractory (R/R) chronic lymphocytic leukemia or non-Hodgkin lymphoma. Results from the relapsed/refractory (R/R) follicular lymphoma (FL) cohort (N = 48) of this trial were recently published in Blood Advances by Shah et al. Patients had received a median of 3 (range, 1–12) prior lines of therapy. 

Key data: The overall response rate (ORR) with pirtobrutinib was 52.1% (95% confidence interval [CI], 37.2–66.7), including a 16.7% complete response (CR) rate and a 35.4% partial response (PR) rate. Median duration of response (DoR) was 10.2 months (95% CI, 3.7–25.7). Median progression-free survival (PFS) was 5.8 months (95% CI, 3.8–8.1), and median overall survival (OS) was not reached. The most common Grade ≥3 treatment-emergent adverse event (TEAE) was neutropenia/decreased neutrophil count (14.6%). In total, 4.2% of patients discontinued treatment due to TEAEs.  

Key learning: Pirtobrutinib demonstrated promising efficacy with a favorable safety profile in heavily pretreated patients with R/R FL, warranting further investigation as monotherapy or in combination.