Smart start: Final results of rituximab, lenalidomide, and ibrutinib lead in prior to combination with chemotherapy for patients with newly diagnosed diffuse large B-cell lymphoma.

7508 Background: The non-germinal center (non-GCB) subtype of Diffuse Large B-cell Lymphoma (DLBCL) is associated with inferior outcomes from standard immuno-chemotherapy. The BTK inhibitor ibrutinib (I) and immunomodulatory agent lenalidomide (L) have promising activity in non-GCB DLBCL as single agents, and result in synthetic lethality in non-GCB DLBCL models when combined. In relapsed non-GCB DLBCL, rituximab (R), L and I result in overall response rate (ORR) of 55% (Ramchandren, ASH 2018). We report the final results of RLI prior to chemotherapy in newly diagnosed non-GCB DLBCL patients, an investigator initiated, single-arm, open-label, phase 2 study. Methods: Adult patients with non-GCB DLBCL, determined by the Hans method, with adequate organ function and performance status were eligible. The primary objectives were to determine (1A) the ORR of two cycles of RLI as initial therapy, and (1B) the complete response rate (CRR) after 6 cycles of chemotherapy combined with RLI. All patients were treated with rituximab 375 mg/m2 IV day 1, ibrutinib 560 mg po daily, and lenalidomide 25 mg po days 1-10 of 21 day cycles for 2 cycles, followed by 6 additional cycles of RLI with chemotherapy. Results: The protocol accrued 60 patients from May 2016 – February 2019, with 52 patients evaluable for disease response (2 withdrew consent prior to restaging, 6 pending restaging prior to abstract deadline). The median age was 64 years (range: 30-83), 28% were ≥ 70 years, and 50% were female. Half the patients had poor risk IPI, 61% had advanced stage, and 71% had a Ki-67 of ≥ 80%. One patient had a fatal fungal infection (CNS aspergillosis) attributed to high dose corticosteroids and RLI, leading to prohibition of corticosteroids during the RLI only cycles with no further fungal infections identified. The ORR for 2 cycles of RLI was 84.6% (n=44), and the CRR was 38.5% (n=20). One patient refused to proceed with the pre-planned chemotherapy after achieving a CR with 2 cycles of RLI, and remains relapse free 18 months later. Conclusions: The Smart Start trial demonstrates the chemotherapy-free combination of rituximab 375 mg/m2, ibrutinib 560 mg, and lenalidomide 25 mg is highly effective in patients with newly diagnosed non-GCB DLBCL. Additional studies evaluating more cycles of RLI with less chemotherapy consolidation are planned. Clinical trial information: NCT02636322.