Smart Stop Trial Shows Targeted Therapy-First Strategy Reduces Chemotherapy Need in Large B-Cell Lymphoma
核心洞察
The Smart Stop trial demonstrated that over 50% of newly diagnosed large B-cell lymphoma (搜索) patients may reduce or eliminate chemotherapy using a targeted therapy-first approach with lenalidomide, tafasitamab, rituximab, and acalabrutinib.
After 4 cycles of targeted therapy, patients achieved a 90% overall response rate with 57% complete response, and the complete response rate reached 96.7% at end of treatment.
The strategy preserved curative intent with 2-year progression-free survival and overall survival rates of 86.5% and 98.4%, respectively, while maintaining effectiveness of subsequent chemotherapy when needed.
The Smart Stop trial (NCT04978584) has demonstrated that a targeted therapy-first strategy can allow more than half of patients with newly diagnosed large B-cell lymphoma (搜索) (LBCL (搜索)) to reduce or eliminate chemotherapy while preserving curative intent, according to primary analysis results presented at the 2025 ASH Annual Meeting.
The phase 2, open-label, single-center study enrolled 61 patients who received a combination of lenalidomide, tafasitamab, rituximab, and acalabrutinib (LTRA) as initial treatment, with chemotherapy reserved for patients who did not achieve complete response.
Treatment Protocol and Patient Population
Patients received 21-day cycles of 25 mg lenalidomide daily on days 1-10, 12 mg/kg intravenous tafasitamab weekly on days 1, 8, and 15, 375 mg/m² intravenous rituximab on day 1, and 100 mg oral acalabrutinib twice daily on days 1-21. After 4 cycles of LTRA, patients achieving complete response either received 2 cycles of CHOP (cohort 1) or continued without chemotherapy (cohort 2), while those without complete response received 6 cycles of CHOP plus LTRA.
The study population had a median age of 61 years (range 23-91), with 56% having an ECOG performance status of 1, 70% with elevated lactate dehydrogenase, and 75% presenting with stage III or IV disease. Notably, 56% had an International Prognostic Index score of 3-5, with 72% classified as high risk. The cohort included 16% of patients with MYC (搜索) and BCL2 (搜索) or BCL6 translocations.
Efficacy Results
After 4 cycles of LTRA, the overall response rate reached 90%, with complete response and partial response rates of 57% and 33%, respectively. The complete response rate at end of treatment was 96.7%.
"In this study, we showed very promising outcomes, both in terms of response rates and durability of response," said Jason Westin, MD, professor in the Department of Lymphoma and Myeloma at The University of Texas MD Anderson Cancer Center, who presented the data.
Cohort 1 achieved a 100% overall response rate, including complete response and partial response rates of 63% and 37%, respectively. Cohort 2 demonstrated complete response and partial response rates of 52% and 29%, respectively.
The 2-year progression-free survival and overall survival rates were 86.5% and 98.4%, respectively, after a median follow-up of 25.3 months. Among patients who received less than complete response after 4 cycles of LTRA and went on to receive CHOP plus LTRA therapy for 6 cycles, the complete response rate was 92%.
Preserving Chemotherapy Effectiveness
A critical finding was that the targeted therapy-first approach did not compromise subsequent chemotherapy effectiveness. All 4 patients who experienced progression achieved complete response with subsequent frontline chemotherapy regimens.
"This is important. This shows that lack of response to the target therapy did not compromise the ability to deliver and have a promising result to the chemotherapy," Westin explained.
Safety Profile
The most common adverse effects of any grade included anemia (90%), neutropenia (87%), decreased platelet count (77%), fatigue (67%), maculopapular rash (46%), transaminitis (43%), nausea (38%), headache (36%), and increased creatinine (36%). The majority of planned doses were received: lenalidomide (88%), tafasitamab (93%), and acalabrutinib (100%).
Clinical Rationale
The study addresses limitations of current LBCL (搜索) treatment, where the CHOP regimen fails to cure one in three patients with newly diagnosed disease. Westin noted that CHOP is "poorly targeted" and that current classification systems have limited utility in determining optimal treatment for individual patients.
"We have an emerging problem in large B-cell lymphoma (搜索) of an incredible wealth of new agents that are [being evaluated] in phase 3 [trials]. But effectively, these studies are all 1970s chemotherapy vs 1970s chemotherapy with a novel agent added to it," Westin said, describing what he calls a "coming chaos of choice."
Future Directions
The investigators plan to expand the Smart Stop trial to a multisite study and evaluate additional agents including glofitamab, polatuzumab, and golcadomide as part of the smart strategy approach. They are also planning randomized trials comparing targeted therapy combinations against standard chemotherapy.
"The smart strategy of targeted therapy first is successful, and it preserves curative intent," Westin concluded. "The smart strategy of targeted therapy first showed that more than half of patients may reduce or remove chemotherapy for newly diagnosed diffuse large B-cell lymphoma (搜索)."