Mantle Cell, Follicular, and Other Indolent B-Cell Lymphoma—Clinical Studies: Prognostic Markers and Therapies in Mantle Cell Lymphoma and Waldenstrom's Macroglobulinemia

145  Rituximab/Bendamustine and Rituximab/Cytarabine (RB/RC) Induction Chemotherapy for Transplant-Eligible Patients with Mantle Cell Lymphoma: A Pooled Analysis of Two Phase 2 Clinical Trials and Off-Trial Experience

Reid W Merryman, et al.

The Abstract concludes: Induction therapy with RB/RC followed by ASCT achieved high rates of durable remissions in two phase 2 clinical trials. Similarly favorable outcomes were observed with off-trial use of this regimen both at an academic center and in community practices. RB/RC is therefore an excellent choice of induction therapy for TE pts with uMCL, and could be further tested in comparative prospective trials. Sequential, rather than alternating, RB/RC cycles and lower dose cytarabine may reduce the risk of prolonged thrombocytopenia post-ASCT.

146  Bortezomib Maintenance (BM) or Consolidation (BC) Following Aggressive Immunochemotherapy and Autologous Stem Cell Transplant (ASCT) for Untreated Mantle Cell Lymphoma (MCL): 8 Year Follow up of CALGB 50403 (Alliance)

Lawrence D Kaplan, et al.

The Abstract concludes: Induction chemotherapy followed by ASCT and either BC or BM was efficacious and tolerable, although BC was associated with more withdrawals for toxicity. PFS was not significantly different between BC and BM. The comparison between studies 50403 and 59909 with long-term follow up continues to suggest a PFS benefit from the addition of BC or BM among patients undergoing transplant. This did not translate into a PFS benefit from time of study enrollment possibly due to the higher pre-transplant dropout rate in 50403. MRD-negativity following induction chemo-immunotherapy is highly associated with improved PFS and the role of ASCT in post-induction MRD-negative patients is currently under investigation in a randomized clinical trial.

Support: U10CA180821, U10CA180882, U24CA196171; ClinicalTrials.gov Identifier: NCT00310037

147  Circulating Tumor DNA Dynamics during Therapy Predict Outcomes in Mantle Cell Lymphoma

Rahul Lakhotia, et al.

The Abstract concludes: Circulating tumor DNA is detectable in nearly all patients with MCL. Dynamic changes that occur very early during therapy may predict clinical outcomes and may be an early readout for the activity of targeted agents. Given its broad applicability, ctDNA should be prospectively studied as part of response-adapted approaches in MCL.

This work was supported by the Intramural Research Program of NCI and Adaptive Biotechnologies, Inc.

148  Safety and Activity of the Investigational Bruton Tyrosine Kinase Inhibitor Zanubrutinib (BGB-3111) in Patients with Mantle Cell Lymphoma from a Phase 2 Trial

Yuqin Song, MD, et al.

The Abstract concludes: Zanubrutinib was shown to be highly active in patients with R/R MCL, as demonstrated by a high rate of CR documented by PET-based imaging. Zanubrutinib was generally well-tolerated, consistent with previous reports of zanubrutinib treatment in patients with various B-cell malignancies.

149  Ibrutinib Treatment in Waldenström’s Macroglobulinemia: Follow-up Efficacy and Safety from the iNNOVATE^TM Study

Christian Buske, et al.

The Abstract concludes: IR showed continued superiority over R, in treatment-naïve and previously treated pts with WM, regardless of genotypic factors. Similarly, in heavily pretreated, RTX-refractory pts with follow-up >3 y, single-agent ibr was highly active and response improved over time. Alone or in combination, ibr had a manageable safety profile and no new safety signals were identified with longer follow-up.

150  Progression Risk-Based Classification of Asymptomatic Waldenström Macroglobulinemia

Mark Bustoros, et al.

The Abstract concludes: We have assembled the largest cohort of SWM patients to date, which allowed us to identify four independent predictors of progression to overt disease: BM infiltration ≥ 70%, IgM ≥ 4,500 mg/dL, b2m ≥ 4.0 mg/dL and albumin < 3.5 g/dL. Using those variables in a proportional hazards model, we developed a robust, flexible classification system based on risk of progression to symptomatic WM. This system stratifies SWM patients into low-, intermediate- and high-risk groups and thus has the potential to inform patient monitoring and care. Most importantly, it can help identify high-risk patients who might benefit from early intervention in this rare malignancy.