Anti-B-Cell Maturation Antigen BiTE Molecule AMG 420 Induces Responses in Multiple Myeloma

PURPOSE

The anti-B-cell maturation antigen BiTE molecule AMG 420 was assessed in patients with relapsed/refractory multiple myeloma.

PATIENTS AND METHODS

In this first-in-human study, up to 10 cycles of AMG 420 were given (4-week infusions/6-week cycles). Patients had progression after ≥ 2 lines of prior therapy and no extramedullary disease. Minimal residual disease (MRD) response was defined as < 1 tumor cell/10⁴ bone marrow cells by flow cytometry.

RESULTS

Forty-two patients received AMG 420 at 0.2-800 μg/d. Median age was 65 years, and median disease duration was 5.2 years. Median exposure was 1 cycle (range, 1-10 cycles) and 7 cycles (range, 1-10 cycles) for responders. Patients discontinued for disease progression (n = 25), adverse events (AEs; n = 7), death (n = 4), completion of 10 cycles (n = 3), and consent withdrawal (n = 1). Two patients remain on treatment. There were 2 nontreatment-related deaths from AEs, influenza/aspergillosis and adenovirus-related hepatitis. Serious AEs (n = 20; 48%) included infections (n = 14) and polyneuropathy (n = 2); treatment-related serious AEs included 2 grade 3 polyneuropathies and 1 grade 3 edema. There were no grade ≥ 3 CNS toxicities or anti-AMG 420 antibodies. In this study, 800 μg/d was considered to not be tolerable because of 1 instance each of grade 3 cytokine release syndrome and grade 3 polyneuropathy, both of which resolved. The overall response rate was 31% (n = 13 of 42). At the maximum tolerated dose (MTD) of 400 μg/d, the response rate was 70% (n = 7 of 10). Of these, five patients experienced MRD-negative complete responses, and 1 had a partial response, and 1 had a very good partial response; all 7 patients responded during the first cycle, and some responses lasted > 1 year.

CONCLUSION

In this study of AMG 420 in patients with relapsed/refractory multiple myeloma, the response rate was 70%, including 50% MRD-negative complete responses, at 400 μg/d, the MTD for this study.

Evaluation of AMG 420, an anti-BCMA bispecific T-cell engager (BiTE) immunotherapy, in R/R multiple myeloma (MM) patients: Updated results of a first-in-human (FIH) phase I dose escalation study

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Background: Objectives of this study included assessing safety and activity of AMG 420/BI 836909, which binds BCMA (B-Cell Maturation Antigen) on MM cells and CD3 on T cells, in relapsed and/or refractory (R/R) MM. Methods: In this FIH study, 6-week cycles of AMG 420 were given for ≤5 cycles or until disease progression (PD), toxicity, or consent withdrawal; 5 more cycles could be given for benefit. Eligible patients had progression after ≥2 lines (incl PI and IMiD). Excluded were PC leukemia, extramedullary relapse, CNS involvement, or prior allo-SCT. MRD was defined as <1 tumor cell / 104 bone marrow cells per flow cytometry. Results: As of Dec 10, 2018, 42 patients received AMG 420 (0.2-800 µg/d). Patients D/C for PD (n=24), adverse events (AE, n=7, incl 3 DLTs), death (4), completed 10 cycles (2), and consent (1). Median age was 65 y, median MM duration 5.2 y, and median # prior therapies 4. Patients were treated for a mean (SD) of 2.5 (2.6) cycles. There were 2 deaths from AEs (acute respiratory distress from flu / aspergillosis; fulminant hepatitis related to adenovirus infection); neither treatment related. Of those with serious AEs (SAEs, n=21, 50%), 18 required hospitalization. SAEs occurring in >1 patient were infections (n=12) and polyneuropathy (PN, n=2). Treatment-related SAEs included 2 grade 3 PNs and 1 edema. Grade 2-3 CRS was seen in 3 patients. No anti-AMG 420 Ab were detected. In this study, 800 µg/d was determined to not be tolerable as 2/3 patients had DLTs, 1 case of grade 3 CRS and 1 case of grade 3 PN; both required hospitalization and subsequently resolved. At 400 µg/d, there were 5 minimal residual disease (MRD)-negative sCRs, 1 VGPR, and 1 PR, for a response rate of 7/10 (70%); at Dec datacut, responses lasted for 5.6-10.4 months with 4 patients ongoing on treatment. As of Feb 2019, some responses lasted >1 year. Overall, there were 13/42 responders (6 sCRs, 3 CRs, 2 VGPRs, 2 PRs). Median time to any response was 1 month. Conclusions: In this FIH study of AMG 420, a BiTE vs BCMA, in R/R MM, there was a 70% response rate (7/10) with 5 out of 7 responders achieving a sCR at 400 µg/d, a recommended dose for further investigation. Clinical trial information: NCT02514239.

Insights into early mycobacterial pathogenesis from the zebrafish

Here we discuss the application of the zebrafish as a relatively new model host for the study of mycobacterial pathogenesis. Recent advances in our understanding of host-mycobacteria interactions from the zebrafish include insights into the role of the innate immune system in both controlling and facilitating infection. Analysis in the zebrafish has revealed that innate macrophages restrict initial bacterial growth, but also convey infecting bacteria into the granuloma, which serves as a place for bacterial growth and spread. Bacterial virulence determinants interact with these processes at different steps in pathogenesis, which can be dissected in these living see-through hosts. As these studies uncover new facets of the bacteria-host interactions in tuberculosis they raise even more questions for future investigation.

Role of CXCR5 and CCR7 in follicular Th cell positioning and appearance of a programmed cell death gene-1high germinal center-associated subpopulation

Th cell access to primary B cell follicles is dependent on CXCR5. However, whether CXCR5 induction on T cells is sufficient in determining their follicular positioning has been unclear. In this study, we find that transgenic CXCR5 overexpression is not sufficient to promote follicular entry of naive T cells unless the counterbalancing influence of CCR7 ligands is removed. In contrast, the positioning of Ag-engaged T cells at the B/T boundary could occur in the absence of CXCR5. The germinal center (GC) response was 2-fold reduced when T cells lacked CXCR5, although these T cells were able to access the GC. Finally, CXCR5(high)CCR7(low) T cells were found to have elevated IL-4 transcript and programmed cell death gene-1 (PD-1) expression, and PD-1(high) cells were reduced in the absence of T cell CXCR5 or in mice compromised in GC formation. Overall, these findings provide further understanding of how the changes in CXCR5 and CCR7 expression regulate Th cell positioning during Ab responses, and they suggest that development and/or maintenance of a PD-1(high) follicular Th cell subset is dependent on appropriate interaction with GC B cells.

Naive CD4 T cells constitutively express CD40L and augment autoreactive B cell survival

Chronic engagement of the B cell receptor by soluble autoantigen leads to reduced B cell survival. Using the Ig and hen egg lysozyme double transgenic mouse model, we demonstrate that the survival of soluble autoantigen-engaged B cells is further reduced in mice lacking CD4 T cells or deficient in CD40. Mixed bone marrow chimera experiments reveal that, under homeostatic conditions, the CD40L-CD40 pathway can augment autoreactive B cell survival in a non-cell-autonomous manner. Naive CD4 T cells are shown to constitutively express CD40L mRNA and protein, although cell surface CD40L abundance is low because of engagement with CD40 on other cells. These observations indicate that the CD40L-CD40 pathway can augment the survival of autoantigen-engaged B cells in the absence of T cell activation. We propose that constitutive CD40L expression by naive CD4 T cells influences the composition of the B cell repertoire and may also affect the homeostasis of other cell types such as regulatory T cells in lymphoid organs.

Germinal center dark and light zone organization is mediated by CXCR4 and CXCR5

Germinal center (GC) dark and light zones segregate cells undergoing somatic hypermutation and antigen-driven selection, respectively, yet the factors guiding this organization are unknown. We report here that GC organization was absent from mice deficient in the chemokine receptor CXCR4. Centroblasts had high expression of CXCR4 and GC B cells migrated toward the CXCR4 ligand SDF-1 (CXCL12), which was more abundant in the dark zone than in the light zone. CXCR4-deficient cells were excluded from the dark zone in the context of a wild-type GC. These findings establish that GC organization depends on sorting of centroblasts by CXCR4 into the dark zone. In contrast, CXCR5 helped direct cells to the light zone and deficiency in CXCL13 was associated with aberrant light zone localization.

Reduced competitiveness of autoantigen-engaged B cells due to increased dependence on BAFF

Peripheral autoantigen binding B cells are poorly competitive with naive B cells for survival and undergo rapid cell death. However, in monoclonal Ig-transgenic mice lacking competitor B cells, autoantigen binding B cells can survive for extended periods. The basis for competitive elimination of autoantigen binding B cells has been unknown. Here we demonstrate that autoantigen binding B cells have increased dependence on BAFF for survival. In monoclonal Ig-transgenic mice, each autoantigen binding B cell receives elevated amounts of BAFF, exhibiting increased levels of NFkappaB p52 and of the prosurvival kinase Pim2. When placed in a diverse B cell compartment, BAFF receptor engagement and signaling are reduced and the autoantigen binding cells are unable to protect themselves from Bim and possibly other death-promoting factors induced by chronic BCR signaling. These findings indicate that under conditions where BAFF levels are elevated, autoantigen-engaged cells will be rescued from rapid competitive elimination, predisposing to the development of autoimmune disease.

IL-25 induces IL-4, IL-5, and IL-13 and Th2-associated pathologies in vivo

We have characterized a cytokine produced by Th2 cells, designated as IL-25. Infusion of mice with IL-25 induced IL-4, IL-5, and IL-13 gene expression. The induction of these cytokines resulted in Th2-like responses marked by increased serum IgE, IgG(1), and IgA levels, blood eosinophilia, and pathological changes in the lungs and digestive tract that included eosinophilic infiltrates, increased mucus production, and epithelial cell hyperplasia/hypertrophy. In addition, our studies show that IL-25 induces Th2-type cytokine production by accessory cells that are MHC class II(high), CD11c(dull), and lineage(-). These results suggest that IL-25, derived from Th2 T cells, is capable of amplifying allergic type inflammatory responses by its actions on other cell types.

IL-4 exacerbates disease in a Th1 cell transfer model of colitis

IL-4 is associated with Th2-type immune responses and can either inhibit or, in some cases, promote Th1-type responses. We tested the effect of IL-4 treatment on the development of inflammation in the CD4(+)CD45RB(high) T cell transfer model of colitis, which has been characterized as a Th1-dependent disease. IL-4 treatment significantly accelerated the development of colitis in immunodeficient recipients (recombinase-activating gene-2 (Rag2)(-/-)) of CD4(+)CD45RB(high) T cells. Quantitative analysis of mRNA expression in the colons of IL-4-treated mice showed an up-regulation of both Th1- and Th2-associated molecules, including IFN-gamma, IP-10, MIG, CXCR3, chemokine receptor-8, and IL-4. However, cotreatment with either IL-10 or anti-IL-12 mAb effectively blocked the development of colitis in the presence of exogenous IL-4. These data indicate that IL-4 treatment exacerbates a Th1-mediated disease rather than induces Th2-mediated inflammation. As other cell types besides T cells express the receptor for IL-4, the proinflammatory effects of IL-4 on host cells in Rag2(-/-) recipients were assessed. IL-4 treatment was able to moderately exacerbate colitis in Rag2(-/-) mice that were reconstituted with IL-4Ralpha-deficient (IL-4Ralpha(-/-)) CD4(+)CD45RB(high) T cells, suggesting that the IL-4 has proinflammatory effects on both non-T and T cells in this model. IL-4 did not cause colitis in Rag2(-/-) mice in the absence of T cells, but did induce an increase in MHC class II expression in the lamina propria of the colon, which was blocked by cotreatment with IL-10. Together these results indicate that IL-4 can indirectly promote Th1-type inflammation in the CD4(+)CD45RB(high) T cell transfer model of colitis.

Novel p19 protein engages IL-12p40 to form a cytokine, IL-23, with biological activities similar as well as distinct from IL-12

A novel sequence discovered in a computational screen appears distantly related to the p35 subunit of IL-12. This factor, which we term p19, shows no biological activity by itself; instead, it combines with the p40 subunit of IL-12 to form a novel, biologically active, composite cytokine, which we term IL-23. Activated dendritic cells secrete detectable levels of this complex. IL-23 binds to IL-12R beta 1 but fails to engage IL-12R beta 2; nonetheless, IL-23 activates Stat4 in PHA blast T cells. IL-23 induces strong proliferation of mouse memory (CD4(+)CD45Rb(low)) T cells, a unique activity of IL-23 as IL-12 has no effect on this cell population. Similar to IL-12, human IL-23 stimulates IFN-gamma production and proliferation in PHA blast T cells, as well as in CD45RO (memory) T cells.

Amyloid peptides are toxic via a common oxidative mechanism

beta-Amyloid protein (A beta) is a member of a small group of proteins that accumulate as amyloid deposits in various tissues. It has recently been demonstrated that the toxicity of A beta toward some neural cells is caused by oxidative damage. Since all of the amyloid diseases are characterized by protein deposited in the antiparallel beta-sheet conformation, it was asked whether there is a common toxic mechanism. It is shown here that the protein components of other human amyloidoses, including amylin, calcitonin, and atrial natriuretic peptide, are all toxic to clonal and primary cells. The toxicity is mediated via a free radical pathway indistinguishable from that of A beta. Experiments with synthetic peptides suggest that it is the amphiphilic nature of the peptides generated by their beta structure rather than their beta structure per se that causes toxicity. These results tend to rule out the alternative that amyloid toxicity is exclusively mediated via specific cell surface receptors.

Hydrogen peroxide mediates amyloid beta protein toxicity

Amyloid beta protein (A beta) is a 40-43 amino acid peptide that is associated with plaques in the brains of Alzheimer's patients and is cytotoxic to cultured neurons. Using both primary central nervous system cultures and clonal cell lines, it is shown that a number of anti-oxidants protect cells from A beta toxicity, suggesting that at least one pathway to A beta cytotoxicity results in free radical damage. A beta causes increased levels of H2O2 and lipid peroxides to accumulate in cells. The H2O2-degrading enzyme catalase protects cells from A beta toxicity. Clonal cell lines selected for their resistance to A beta toxicity also become resistant to the cytolytic action of H2O2. In addition, A beta induces the activity of NF-kappa B, a transcription factor thought to be regulated by oxidative stress. Finally, A beta-induced H2O2 production and A beta toxicity are blocked by reagents that inhibit flavin oxidases, suggesting that A beta activates a member of this class of enzymes. These results show that the cytotoxic action of A beta on neurons results from free radical damage to susceptible cells.