Brentuximab vedotin activity in diffuse large B-cell lymphoma with CD30 undetectable by visual assessment of conventional immunohistochemistry.

This phase 2 study evaluated brentuximab vedotin monotherapy in CD30-expressing DLBCL; after several patients with little to no CD30 achieved a complete remission (CR), the study evaluated treatment of DLBCL with undetectable CD30 (CD30u) by local visual immunohistochemistry (vIHC). Sixteen of 52 CD30u DLBCL patients (31%) had an objective response (6 CRs [12%]). Median progression-free survival (PFS) was 1.4 months (range, 0.4-15.6) and median overall survival (OS) was 7.5 months (range, 0.7-18.6+). Subsequent CD30 expression quantitated by computer-assisted digital image analysis (cIHC) showed that 11 of 16 CD30u DLBCL responders had ≥1% CD30. Correlative analyses of CD30u and CD30-expressing DLBCL combined demonstrated that ≥1% CD30 expression by cIHC resulted in a trend toward a higher response rate and significantly longer median PFS and OS. A minimum CD30 expression threshold appears to be required for antitumor activity in DLBCL; however, other factors also likely contribute to activity. (NCT01421667).