Ibrutinib, a Bruton’s tyrosine kinase (BTK) inhibitor, is FDA approved for several myeloid malignancies, including chronic lymphocytic leukemia and mantle-cell lymphoma. Although some clinicians have also used ibrutinib for nonapproved conditions such as relapsed/refractory diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL), little is known about its efficacy and safety in patients with these conditions. In this exploratory analysis, researchers retrospectively evaluated patients with DLBCL, Richter transformation (RT), or FL.
Data collected included patient demographics, disease stage, prior treatments, ibrutinib dose, International Prognostic Index, duration of therapy, reasons for discontinuation, and response. Study end points were progression-free survival (PFS) and overall survival.
A total of 44 patients were included in the analysis—24 with DLBCL, 12 with FL, and 8 with RT. Patients ranged from 19 to 80 years of age, 61% were male, and most had good performance status, as measured by Eastern Cooperative Oncology Group performance status. The median number of prior therapies was 5 (range, 1-11). The most common reasons for ibrutinib discontinuation were disease progression (35%) and treatment-related toxicity (20%).
Overall, results in this real-world study were similar to prior clinical trial data. In FL, responses appear to be durable, with median PFS exceeding 10 months. Notably, PFS was superior in RT compared with DLBCL (P = 0.03). Based on the data, the researchers recommended that ibrutinib not be used as monotherapy in DLBCL, but rather as a short-term bridge to more definitive therapies when clinically appropriate. Differences in response between different myeloid malignancies suggested differing dependence on BTK signaling.
Isaac K, et al. ASCO Abstract e19043.