Activity of tafasitamab in combination with rituximab in subtypes of aggressive lymphoma

Background

Despite recent advances in the treatment of aggressive lymphomas, a significant fraction of patients still succumbs to their disease. Thus, novel therapies are urgently needed. As the anti-CD20 antibody rituximab and the CD19-targeting antibody tafasitamab share distinct modes of actions, we investigated if dual-targeting of aggressive lymphoma B-cells by combining rituximab and tafasitamab might increase cytotoxic effects.

Methods

Antibody single and combination efficacy was determined investigating different modes of action including direct cytotoxicity, antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) in in vitro and in vivo models of aggressive B-cell lymphoma comprising diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL).

Results

Three different sensitivity profiles to antibody monotherapy or combination treatment were observed in in vitro models: while 1/11 cell lines was primarily sensitive to tafasitamab and 2/11 to rituximab, the combination resulted in enhanced cell death in 8/11 cell lines in at least one mode of action. Treatment with either antibody or the combination resulted in decreased expression of the oncogenic transcription factor MYC and inhibition of AKT signaling, which mirrored the cell line-specific sensitivities to direct cytotoxicity. At last, the combination resulted in a synergistic survival benefit in a PBMC-humanized Ramos NOD/SCID mouse model.

Conclusion

This study demonstrates that the combination of tafasitamab and rituximab improves efficacy compared to single-agent treatments in models of aggressive B-cell lymphoma in vitro and in vivo.

Development of a Prognostic Scoring System using MYC Expression and Soluble Interleukin Receptor -2 level for Diffuse Large B-cell Lymphoma

Background

Diffuse large B-cell lymphoma, not otherwise specified (DLBCL-NOS), is the most frequent type of lymphoid neoplasm.

Methods

We investigated the relationships between clinical factors of DLBCL-NOS and MYC immunohistochemistry (IHC) staining.

Results

A total of 110 patients diagnosed with DLBCL-NOS from 2012 to 2020 at Tottori University Hospital and treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP) chemotherapy were included. IHC staining of MYC in formalin-fixed, paraffin-embedded tumor specimens was performed, and ROC-curve analysis revealed the cut-off value of the MYC positive rate as 55%. The 2-year overall survival (OS) rates of the MYC-negative and -positive groups were 84.7% vs 57.7% (P = 0.0091), and the progression-free survival rates were 77.8% vs 54.7% (P = 0.016), respectively. Multivariate analysis for OS showed prognostic significance of MYC positivity [hazards ratio (HR): 2.496; P = 0.032], and serum levels of soluble interleukin-2 receptor (sIL-2R) > 2000 U/mL (HR: 3.950; P = 0.0019), as well as age > 75 (HR: 2.356; P = 0.068). The original scoring system was developed based on these findings. By assigning one point to each item, age (> 75), MYC positivity, and sIL-2R level (> 2000), all patients were classified into three risk categories: group 1 (0 points), group 2 (1 point), and group 3 (2-3 points). The 2-year survival rates were 100%, 83.0%, and 47.1% for the groups 1, 2, and 3, respectively (P < 0.0001).

Conclusion

We suggest that a prognostic scoring system using MYC expression and soluble interleukin receptor -2 level is useful for the prediction of prognosis, contributing to further stratification in DLBCL-NOS.

MYC: a multipurpose oncogene with prognostic and therapeutic implications in blood malignancies

MYC oncogene is a transcription factor with a wide array of functions affecting cellular activities such as cell cycle, apoptosis, DNA damage response, and hematopoiesis. Due to the multi-functionality of MYC, its expression is regulated at multiple levels. Deregulation of this oncogene can give rise to a variety of cancers. In this review, MYC regulation and the mechanisms by which MYC adjusts cellular functions and its implication in hematologic malignancies are summarized. Further, we also discuss potential inhibitors of MYC that could be beneficial for treating hematologic malignancies.

Integrated analysis of transcriptome, methylome and copy number aberrations data of marginal zone lymphoma and follicular lymphoma in dog

Marginal zone lymphoma (MZL) and follicular lymphoma (FL) are classified as indolent B-cell lymphomas in dogs. Aside from the clinical and histopathological similarities with the human counterpart, the molecular pathogenesis remains unclear. We integrated transcriptome, genome-wide DNA methylation and copy number aberration analysis to provide insights on the pathogenesis of canine MZL (n = 5) and FL (n = 7), also comparing them with diffuse large B-cell lymphoma (DLBCL). Transcriptome profiling highlighted the presence of similar biological processes affecting both histotypes, including BCR and TLR signalling pathways. However, FLs showed an enrichment of E2F targets, whereas MZLs were characterized by MYC-driven transcriptional activation signatures. FLs showed a distinctive loss on chr1 containing CEACAM23 and 24, conversely MZLs presented multiple recurrent gains on chr13, where MYC is located. The distribution of methylation peaks was similar between the two histotypes. Integrating data from the three omics, FLs resulted clearly separated from MZLs and DLBCL dataset. MZLs showed the enrichment of FoxM1 network and TLR associated TICAM1-dependent IRFs activation pathway. However, no specific signatures differentiated MZLs from DLBCLs. In conclusion, our study presents the first comprehensive analysis of molecular and epigenetic pathogenesis of canine FL and MZL.

MYC's Fine Line Between B Cell Development and Malignancy

The transcription factor MYC is transiently expressed during B lymphocyte development, and its correct modulation is essential in defined developmental transitions. Although temporary downregulation of MYC is essential at specific points, basal levels of expression are maintained, and its protein levels are not completely silenced until the B cell becomes fully differentiated into a plasma cell or a memory B cell. MYC has been described as a proto-oncogene that is closely involved in many cancers, including leukemia and lymphoma. Aberrant expression of MYC protein in these hematological malignancies results in an uncontrolled rate of proliferation and, thereby, a blockade of the differentiation process. MYC is not activated by mutations in the coding sequence, and, as reviewed here, its overexpression in leukemia and lymphoma is mainly caused by gene amplification, chromosomal translocations, and aberrant regulation of its transcription. This review provides a thorough overview of the role of MYC in the developmental steps of B cells, and of how it performs its essential function in an oncogenic context, highlighting the importance of appropriate MYC regulation circuitry.

The Spectrum of MYC Alterations in Diffuse Large B-Cell Lymphoma

MYC, as a powerful transcription factor, plays a vital role in various cancers. The clinical significance of MYC alterations in diffuse large B-cell lymphoma (DLBCL) has been investigated for a long time. In this study, we comprehensively summarize the different alterations of MYC in DLBCL, including MYC overexpression, MYC translocations, MYC mutations, and increased gene copy number of MYC. Noteworthy, lone MYC overexpression or MYC translocation is not significantly associated with poor clinical outcomes, and their detrimental effects depend on the genetic alterations of BCL2 or BCL6. Both double-expressor DLBCL (DE-DLBCL), defined as overexpression of MYC and BCL2 proteins, and double-hit lymphoma (DHL), defined as a dual translocation of MYC together with BCL2 or BCL6, represent the distinct subgroups of DLBCL with inferior clinical outcomes. The mechanism may be that MYC activation induces cell proliferation, without the threat of the apoptotic brake in the presence of BCL2 overexpression. In addition, most of MYC mutations are present with favorable prognosis, and the nonsignificant effect of MYC copy number amplification has been observed. It has been proved that cyclophosphamide, doxorubicin, vincristine, and prednisone plus rituximab show limited effects for DHL or DE-DLBCL, and the rituximab plus dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin seem to be efficacious for DHL. The novel therapy is urgently needed for clinical improvement in DHL and DE-DLBCL.

Cross-talk between Myc and p53 in B-cell lymphomas

Myc and p53 proteins are closely associated with many physiological cellular functions, including immune response and lymphocyte survival, and are expressed in the lymphoid organs, which are sites for the development and activation of B-cell malignancies. Genetic alterations and other mechanisms resulting in constitutive activation, rearrangement, or mutation of MYC and TP53 contribute to the development of lymphomas, progression and therapy resistance by gene dysregulation, activation of downstream anti-apoptotic pathways, and unfavorable microenvironment interactions. The cross-talk between the Myc and p53 proteins contributes to the inferior prognosis in many types of B-cell lymphomas. In this review, we present the physiological roles of Myc and p53 proteins, and recent advances in understanding the pathological roles of Myc, p53, and their cross-talk in lymphoid neoplasms. In addition, we highlight clinical trials of novel agents that directly or indirectly inhibit Myc and/or p53 protein functions and their signaling pathways. Although, to date, these trials have failed to overcome drug resistance, the new results have highlighted the clinical efficiency of targeting diverse mechanisms of action with the goal of optimizing novel therapeutic opportunities to eradicate lymphoma cells.

PD-L1 over-expression is driven by B-cell receptor signaling in diffuse large B-cell lymphoma

Targeting the programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) pathway represents a milestone in cancer therapy. However, the biologic features of diffuse large B-cell lymphoma (DLBCL) with PD-L1 expression remains unknown. We evaluated the correlation between pSYK and PD-L1 mRNA levels with RNAscope in situ hybridization and protein levels with immunohistochemistry in 108 cases of DLBCL, 25 of which featured loss of B-cell receptor (BCR), and investigated the effects of BCR signaling and MYC on PD-L1 mRNA and protein level with qPCR, immunoblotting and flow cytometery in DLBCL cell lines. PD-L1 amplification was detected with fluorescent in situ hybridization. Animal studies were applied to validate the in vitro findings. pSYK and MYC correlated with both PD-L1 mRNA and protein level. Genetic aberrations involving PD-L1 were rare in DLBCL. BCR signaling and MYC increased PD-L1 mRNA and protein expression. Inhibition of BCR signaling and BCR knockdown down-regulated PD-L1. DLBCL with a loss of loss of BCR showed low levels of PD-L1 mRNA and protein. PD-L1 was down-regulated by ibrutinib in a xenograft mouse model and correlated with slower tumor growth. In conclusion, this study demonstrates that DLBCL with PD-L1 expression features an activated B-cell receptor signal pathway, and that BCR inhibition and PD-L1 blockage may potentially synergize to targeting DLBCL.

Angelica gigas Nakai and Decursin Downregulate Myc Expression to Promote Cell Death in B-cell Lymphoma

Angelica gigas Nakai (AGN) is an oriental traditional medicine to treat anemia, dysmenorrhea, and migraine. However, its anti-lymphoma effect is yet to be tested. Here, we demonstrated that AGN and its major component decursin target Myc to suppress lymphomagenesis in vitro and in vivo. AGN inhibited cell viability in multiple B lymphoma cells, while sparing normal splenocytes and bone marrow cells. Increased cleaved PARP level and caspase 3/7 activity and the repression of survival-promoting AKT/mTOR and MAPK pathways downstream of BCR, were responsible for the pro-apoptotic effects of AGN. We found that Myc, a prominent downstream target of these signaling pathways, contributes to AGN-induced cell death. Moreover, co-treatment with AGN and a Myc inhibitor, JQ1 or 10058-F4 yielded synergistic cytotoxic activities against cancer cells with markedly reduced Myc expression. AGN downregulated Myc expression and suppressed tumorigenesis in Eμ-myc transgenic mice. The proapoptotic activities of AGN were recapitulated by decursin, indicating that the anti-tumor effect of AGN was mainly caused by decursin. These findings suggest that AGN and decursin possess potent anti-lymphoma activity, and combination therapies with AGN/decursin and a Myc inhibitor to target Myc more efficiently could be a valuable avenue to explore in the treatment of B-cell lymphoma.