Acute myeloid leukemia (AML) is a highly heterogenous disease with multiple signaling pathways contributing to its pathogenesis. A key driver of AML is the FMS-like tyrosine kinase receptor-3 (FLT3). Activating mutations in FLT3, primarily the FLT3-internal tandem duplication (FLT3-ITD), are associated with decreased progression-free and overall survival. Identification of the importance of FLT3-ITD and the FLT3 pathway in the prognosis of patients with AML has stimulated efforts to develop therapeutic inhibitors of FLT3. Although these inhibitors have shown promising antileukemic activity, they have had limited efficacy to date as single agents and may require use in combination with cytotoxic chemotherapies. Here, we review clinical and preclinical results for the clinically mature FLT3 inhibitors currently in development. We conclude that multitargeted FLT3 inhibitors may have more utility earlier in the course of disease, when in vitro evidence suggests that AML cells are less dependent on FLT3 signaling, perhaps because of upregulation of multiple other signaling pathways. More potent agents may have greater utility in relapsed and heavily pretreated patients, in whom high levels of circulating FLT3 ligand may necessitate use of an agent with a very favorable pharmacokinetic/ pharmacodynamic profile. Novel combination regimens are also discussed.

While rituximab has dramatically improved outcomes for patients with CD20 malignancies for two decades, responses are not universal and resistance can develop. Obinutuzumab was developed to potentiate activity and overcome resistance. Pre-clinical data suggests obinutuzumab is superior to rituximab at effecting B cell depletion; however recent phase III clinical trial results have been mixed. The decision of which antibody to employ will probably be further complicated by the approval of a subcutaneous preparation of rituximab and several anti-CD20 biosimilars. Clinicians are now challenged with deciding whether to switch to obinutuzumab in approved settings, accepting the potential for increased toxicity and probable increased cost. The benefit conferred by obinutuzumab over rituximab may be context-specific and vary based on histological subtype and immune integrity. This comprehensive review will explore the preclinical differences, investigate the proposed pathogenesis of rituximab resistance, compare the employed dosing strategies and interrogate available clinical results to help inform practice.

International audienceno abstrac

Frontline bendamustine and rituximab in advanced stage FL has marked efficacy in this population-based analysis.l Early progression within 24 months is associated with poor outcome after BR; however, the majority of patients have transformed lymphoma.Despite widespread use of bendamustine and rituximab (BR) as frontline therapy for advanced-stage follicular lymphoma (FL), little is known about the risk of early progression or incidence of histological transformation. We performed a retrospective analysis of a population-based cohort of 296 patients with advanced-stage FL treated with frontline BR and maintenance rituximab. As previously demonstrated, outcomes with this regimen are excellent, with 2-year event-free survival estimated at 85% (95% confidence interval [95% CI], 80-89) and 2-year overall survival 92% (95% CI, 88-95). Progression of disease within 24 months (POD24) occurred in 13% of patients and was associated with a significantly inferior outcome with 2-year overall survival of 38% (95% CI, 20-55). The only significant risk factor for POD24 at baseline was elevated lactate dehydrogenase (P < .001). Importantly, the majority of POD24 patients (76%) had transformed disease. Compared with a historical cohort treated with rituximab, cyclophosphamide, vincristine, and prednisone, event-free survival has improved and the risk of POD24 has decreased, but a higher proportion of patients with POD24 harbor transformation. The overall incidence of transformation appears unchanged. The presence of occult or early transformation is the main driver of POD24 in FL patients treated with frontline BR. Identification of biomarkers and improved management strategies for transformation will be crucial to improving outcomes.

Cure rates for primary mediastinal large B-cell lymphoma (PMBCL) have improved with the integration of rituximab. However, the type of primary therapy and role of radiotherapy (RT) remains ill-defined. Herein, we evaluated the outcome of PMBCL primarily treated with R-CHOP and the impact of an end-of-treatment (EOT) FDG-PET scan to guide consolidative RT. Patients ≥18 years of age with PMBCL treated with curative intent R-chemotherapy were identified. Prior to 2005, patients were recommended to receive R-CHOP +RT (RT era). Beginning in 2005, EOT PET was used to guide RT and only those with a PET-positive scan received RT (PET era). In total, 159 patients were identified, 94% were treated with R-CHOP and 44% received RT - 78% in RT era, 28% in PET era. The 5-year time to progression (TTP) and OS for the entire cohort were 80% and 89%, respectively, similar across treatment eras. Overall, 10% had refractory disease. In total, 113 patients had an EOT PET scan: 63% negative and 37% positive with a 5-year TTP of 90% vs 71% and 5-year OS of 97% vs 88%, respectively. For those with Deauville (D) scored PET scans (n=103), the 5-year TTP for PET-negative cases by Deauville criteria (D1-D3,DX) was 91%, with inferior outcomes for D5 vs D4 (5-year TTP 33% vs 87%, p=0.0002). Outcomes for R-CHOP treated PMBCL patients treated with R-CHOP are favorable and use of a PET-adapted approach reduces RT in the majority of patients. A small proportion have refractory disease and may benefit from an alternate treatment.

Genomic rearrangements in the MYC locus occur in ∼12% of lymphomas with diffuse large B-cell lymphoma (DLBCL) morphology and are associated with inferior outcome. Previous studies exploring MYC rearrangements have primarily used fluorescence in situ hybridization (FISH) assays to characterize break-apart status but have rarely examined breakpoint location, and in some cases have not examined partner identity. We performed targeted sequencing of MYC, BCL2, BCL6, and the immunoglobulin (IG) loci in 112 tumors with DLBCL morphology harboring MYC rearrangement. We characterized the location of the MYC rearrangement at base pair resolution and identified the partner in 88 cases. We observed a cluster of breakpoints upstream of the MYC coding region and in intron 1 (the “genic cluster”). Genic cluster rearrangements were enriched for translocations involving IGH (80%), whereas nongenic rearrangements occurred mostly downstream of the MYC gene with a variety of partners, including IGL and IGK. Other recurrent partners included BCL6, ZCCHC7, and RFTN1, which has not previously been described as a MYC partner. We compared 2 commercially available FISH break-apart assays for the MYC locus and observed discordant results in 32% of cases examined, including some with MYC-IGL and MYC-IGK rearrangements. In cases of high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangement (HGBL-DH), so-called “double-hit” lymphomas, the majority of MYC rearrangements had non-IG partners (65%), with breakpoints outside the genic cluster (72%). In patients with de novo HGBL-DH of DLBCL morphology, MYC-IG rearrangements showed a trend toward inferior time to progression and overall survival compared with MYC–non-IG rearrangements. Our data reveal clinically relevant architecture of MYC rearrangements in lymphomas with DLBCL morphology.

Consolidative radiation therapy (RT) for advanced-stage diffuse large B-cell lymphoma (DLBCL) remains controversial with routine practice continuing to include RT in patients with initial bulky disease or residual masses. PET-CT is a sensitive modality for detecting the presence of residual disease at end-of-treatment (EOT). A PET-guided approach to selectively administer RT has been policy in BC since 2005. Patients with advanced-stage DLBCL diagnosed between January 2005 - March 2017 treated with at least 6 cycles of R-CHOP that underwent EOT-PET were included in this analysis. Those with complete metabolic response (PET-NEG) were observed; those with PET-positive scans (PET-POS) were offered consolidative RT, when feasible. 723 patients were identified with median follow-up of 4.3 years: 517 (72%) were PET-NEG; 206 (28%) were PET-POS. Time-to-progression (TTP) and overall survival (OS) at 3 years were 83% v 56% and 87% v 64%, for PET-NEG and PET-POS patients, respectively. Non-progressing PET-POS patients treated with consolidative RT (109/206, 53%) had outcomes approaching those of PET-NEG patients, with 3-year estimates of 76% and 80% for TTP and OS. PET-NEG patients with bulky disease (≥10 cm) at diagnosis, had outcomes indistinguishable from those without bulk, despite omitting RT. These data suggest that patients with advanced-stage DLBCL that are PET-NEG at EOT and receive no RT have excellent outcomes. FDG-PET can reliably guide selective administration of consolidative RT, even for patients with initially bulky disease.

Idecabtagene vicleucel (ide-cel) was FDA approved in March 2021 for the treatment of relapsed/refractory multiple myeloma (RRMM) after 4 lines of therapy. On the KarMMa trial, grade ≥3 cytopenias and infections were common. We sought to characterize cytopenias and infections within 100 days after ide-cel in the standard of care (SOC) setting. This multi-center retrospective study included 52 patients who received SOC ide-cel; 47 reached day 90 follow-up. Data was censored at day 100. Grade ≥3 cytopenia was present among 65% of patients at day 30 and 40% of patients at day 90. Granulocyte colony stimulating factor (G-CSF) was administered to 88%, packed red blood cell (pRBC) transfusions to 63%, platelet transfusions to 42%, thrombopoietin (TPO) agonists to 21%, intravenous immunoglobulin (IVIG) to 13%, and CD34+ stem cell boosts to 8%. At day 100, 19% and 13% of patients had ongoing use of TPO agonists and G-CSF, respectively. Infections occurred in 54% of patients and were grade ≥3 in 23%. Earlier infections in the first 30 days were typically bacterial (68%) and severe (50%). Later infections between days 31 - 100 were 50% bacterial and 42% viral; only 13% were grade ≥3. On univariate analysis, high pre-CAR-T marrow myeloma burden (&gt;/= 50%), circulating plasma cells at pre-lymphodepletion (LD), and grade ≥3 anemia at pre-LD were associated with grade ≥3 cytopenia at both days 30 and 90. Longer time from last bridging treatment to LD was the only significant risk factor for infection.