Expression of TCF3 target genes defines a subclass of diffuse large B-cell lymphoma characterized by up-regulation of MYC target genes and poor clinical outcome following R-CHOP therapy.

TCF3 is a lymphopoietic transcription factor that acquires somatic driver mutations in diffuse large B-cell lymphoma (DLBCL). Hypothesizing that expression patterns of TCF3-regulated genes can inform clinical management, we found that unsupervised clustering analysis with 15 TCF3-regulated genes and eight additional ones resolved local DLBCL cases into two main clusters, denoted Groups A and B, of which Group A manifested inferior overall survival (OS, p = 0.0005). We trained a machine learning model to classify samples into the Groups based on expression of the 23 transcripts in an independent validation cohort of 569 R-CHOP-treated DLBCL cases. Group A overlapped with the ABC cell-of-origin subgroup but its prognostic power was superior. GSEA analysis demonstrated asymmetric expression of 30 gene sets between the Groups, pointing to biological differences. We present, validate and make available a novel method to assign DLBCL cases into biologically-distinct groups with divergent OS following R-CHOP therapy.

Step down to 6 months of prophylactic-dose low molecular weight heparin after initial full-dose anticoagulation for the treatment of cancer-associated thrombosis (STEP-CAT): A pilot study.

BACKGROUND: Patients with cancer-associated thrombosis (CAT) are treated with full-dose anticoagulation for at least 3 months, but optimal dosing thereafter is unknown. AIM: We explored the feasibility of extended prophylactic-dose low molecular weight heparin (LMWH) treatment following a minimum of 3 months of full-dose LMWH. METHODS: We conducted a multicenter prospective pilot study of patients with CAT who completed at least 3 months of therapeutic-dose LMWH. Patients received 6 months of prophylactic-dose subcutaneous enoxaparin (40 mg once daily). The primary outcome was recurrence of deep vein thrombosis (DVT) or pulmonary embolism (PE), and secondary outcomes included major, clinically relevant non-major (CRNM), and minor bleeding. RESULTS: From August 2016 to May 2019, 52 patients with a mean age of 64.1 years were included. The study was stopped early because of poor recruitment. Breast (23.1%) and colorectal (19.2%) were the most common cancers, and 61.0% had stage IV malignancy. Index CAT consisted of DVT alone in 57.7% of patients and pulmonary embolism (PE) with or without DVT in 42.3%. Patients received a mean of 7.6 months of weight-adjusted LMWH before enrollment. During a mean follow-up of 5.6 months, one patient was diagnosed with recurrent incidental PE (0.0035 events/subject-month). There were no major bleeding events, one CRNM, and one minor bleeding event. Eight (15.4%) patients died; six from cancer and two from respiratory disease unrelated to PE. CONCLUSIONS: These results, in part, provide support for trials of extended reduced-dose anticoagulation for the secondary prevention of CAT. (ClinicalTrials.gov: NCT02752607).

Unique therapeutic properties and preparation methodology of multivalent rituximab-lipid nanoparticles.

Therapeutic monoclonal antibodies hold great promise in the treatment of cancer and other diseases, but their unclear mechanism of action makes it difficult to identify features that will increase their efficacy. One such feature may be antibody valence, since enhanced therapeutic efficacies have been observed using multivalent, as opposed to bivalent, antibodies. For example, multivalent antibody-lipid nanoparticles (Ab-LNPs) containing rituximab (Rtx) or trastuzumab show significantly increased therapeutic activity compared to equivalent doses of the bivalent antibodies. To more fully understand this phenomenon, we created a methodology reliant on biotin-neutravidin interactions for preparing specific valences of Ab-LNPs that shows improvements in reproducibility, preparation time and overall yield of coupled Ab (up to 80%). We subsequently prepared a series of valences of Rtx-LNPs to examine binding characteristics to CD20+ lymphoma cells, distribution of Rtx-LNPs on the cell surface, modulation of CD20 expression, cytotoxicity of the constructs and ability of the different valences to directly induce apoptosis. As the valence of Rtx-LNP was increased, the amount of Rtx bound to cells increased up to ∼10-fold higher compared to bivalent Rtx. Although more Rtx was bound to cells, there were also surprising increases in the levels of unbound CD20. This suggested the formation of Rtx-enriched microdomains that were confirmed using confocal fluorescence laser-scanning microscopy. Multivalent Rtx-LNPs were significantly more cytotoxic than Rtx; for equivalent doses of drug, Rtx-LNPs elicited apoptosis in two lymphoma cell lines in a valence-dependent manner up to levels that were 14-fold higher than bivalent Rtx. It is suggested that CD20-enriched microdomains may play a role in the mechanism of action of Rtx. This new preparation methodology can be used in future studies evaluating the mechanism of action of multivalent Ab-LNPs prepared with Rtx or other therapeutic Abs.

Multivalent rituximab lipid nanoparticles as improved lymphoma therapies: indirect mechanisms of action and in vivo activity.

AIMS: The activity of therapeutic antibodies can be enhanced by creating multivalent constructs, such as antibody lipid nanoparticles (LNPs). Here, we examine differences between rituximab (Ritux) and Ritux-LNPs in terms of their indirect mechanisms of action: complement-dependent cytotoxicity (CDC) and antibody-dependent cell-mediated cytotoxicity (ADCC). MATERIALS & METHODS: We employed two mantle-cell lymphoma cell lines, Z138 and JVM2, which exhibit different in vivo sensitivities to Ritux along with variable expression levels of cell-surface proteins that regulate ADCC and CDC. RESULTS: In both cell lines, CDC and ADCC were found to be significantly enhanced after treatment with Ritux-LNPs compared with Ritux. In vivo efficacy studies, however, suggested that the therapeutic activities of Ritux and Ritux-LNPs were equivalent, which was subsequently explained in part by pharmacokinetic studies indicating rapid elimination of Ritux-LNP. CONCLUSION: Although indirect and direct mechanisms of multivalent Ritux are enhanced, its further development requires methods to improve its circulation lifetime.

Chemical mapping of ceramide distribution in sphingomyelin-rich domains in monolayers.

The incorporation of ceramide in phase-separated monolayers of ternary lipid mixtures has been studied by a combination of atomic force microscopy (AFM), fluorescence, and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Replacement of a fraction of the sphingomyelin by ceramide in DOPC/SM/cholesterol monolayers leads to changes in the SM-cholesterol-rich liquid-ordered domains. AFM shows the formation of heterogeneous domains with small raised islands that are assigned to a ceramide-rich gel phase. ToF-SIMS provides conclusive evidence for the localization of SM and ceramide in ordered domains and shows that ceramide is heterogeneously distributed in small islands throughout the domains. The results indicate the utility of combining AFM and ToF-SIMS for understanding compositions of phase-separated membranes.

Transition from nanodomains to microdomains induced by exposure of lipid monolayers to air.

The morphology of monolayers prepared from ternary lipid mixtures that have coexisting fluid phases has been examined by atomic force microscopy for samples transferred to mica before and after exposure to air. Mixtures of 1,2-dioleoyl-sn-glycero-3-phosphocholine and cholesterol with either egg sphingomyelin or 1,2-dipalmitoyl-sn-glycero-3-phosphocholine were studied at several surface pressures. Both lipid mixtures have a combination of small islands and large microdomains at low surface pressure (5-10 mN/m) for monolayers deposited in either air or nitrogen. By contrast, monolayers have small interconnected nanodomains when deposited under nitrogen at 30 mN/m but mixtures of large microdomains and small nanodomains when transferred after exposure to air. These results are consistent with an earlier report that concluded that the formation of large domains at high surface pressures (>30 mN/m) for monolayers exposed to air is caused by lipid oxidation. However, the higher spatial resolution available with atomic force microscopy indicates that exposure of the monolayers to air leads to an increase in the size of preexisting nanodomains, rather than a change in the miscibility pressure. Examination of changes in surface morphology as a function of surface pressure demonstrate a gradual evolution in size and surface coverage for both nano- and microdomains, before formation of a network of interconnected nanodomains. Similar studies for binary mixtures in the absence of cholesterol indicate that lipid oxidation results in analogous changes in domain size for monolayers with coexisting gel and fluid phases. These results illustrate the importance of using techniques capable of probing the nanoscale organization of membranes.