Upfront plerixafor plus G-CSF versus cyclophosphamide plus G-CSF for stem cell mobilization in multiple myeloma: efficacy and cost analysis study.

Cyclophosphamide plus G-CSF (C+G-CSF) is one of the most widely used stem cell (SC) mobilization regimens for patients with multiple myeloma (MM). Plerixafor plus G-CSF (P+G-CSF) has demonstrated superior SC mobilization efficacy when compared with G-CSF alone and has been shown to rescue patients who fail mobilization with G-CSF or C+G-CSF. Despite the proven efficacy of P+G-CSF in upfront SC mobilization, its use has been limited, mostly due to concerns of high price of the drug. However, a comprehensive comparison of the efficacy and cost effectiveness of SC mobilization using C+G-CSF versus P+G-CSF is not available. In this study, we compared 111 patients receiving C+G-CSF to 112 patients receiving P+G-CSF. The use of P+G-CSF was associated with a higher success rate of SC collection defined as ⩾5 × 10(6) CD34+ cells/kg (94 versus 83%, P=0.013) and less toxicities. Thirteen patients in the C+G-CSF arm were hospitalized owing to complications while none in the P+G-CSF group. C+G-CSF was associated with higher financial burden as assessed using institutional-specific costs and charges (P<0.001) as well as using Medicare reimbursement rates (P=0.27). Higher rate of hospitalization, increased need for salvage mobilization, and increased G-CSF use account for these differences.

Beyond consolidation: auto-SCT and immunotherapy for plasma cell myeloma.

Autologous hematopoietic cell transplantation (auto-HCT) is the standard consolidation therapy for plasma cell myeloma patients following induction therapy. Auto-HCT improves disease-free survival (DFS), but is generally not curative. The allogeneic HCT experience demonstrated that T-cell immunotherapy can confer long-term DFS. Preclinical and clinical data indicate that myeloma-associated Ags elicit humoral and cellular immune responses (IRs) in myeloma patients. These findings strongly suggest that the immunotherapeutic strategies, including immune checkpoint inhibitors, therapeutic cancer vaccines and adoptive cellular therapies, are promising avenues of clinical research that may be most applicable in the minimal residual disease state following auto-HCT. These strategies are designed to prime or augment antimyeloma IRs and promote a 'host-vs-myeloma' effect that may result in durable DFS. Innovative clinical trials investigating immune checkpoint inhibitors and cancer vaccines have demonstrated that robust immunity against myeloma-associated Ags can be elicited in the setting of auto-HCT. A diverse array of immunotherapeutic strategies have entered clinical trials in myeloma, including PD-1/PD-L1 inhibitors, DC/myeloma cell fusion vaccines and adoptive chimeric Ag receptor T-cell therapy, and further investigation of combinations of immunologic and pharmaceutical agents are expected in the near future. In this review, we will discuss the preclinical data supporting immunotherapy in auto-HCT for myeloma, clinical investigation of these strategies and the future prospects of immunotherapy in pursuit of the goal of curative therapy.

Factors impacting stem cell mobilization failure rate and efficiency in multiple myeloma in the era of novel therapies: experience at Memorial Sloan Kettering Cancer Center.

Thalidomide, lenalidomide and bortezomib have increasingly been incorporated in first-line induction therapies for multiple myeloma. Concerns regarding the impact of these agents, especially lenalidomide, on stem cell mobilization prompted us to re-evaluate the risk factors that impact mobilization, including exposure to novel induction regimens. Among 317 patients who proceeded to stem cell collection after induction therapy between 2000 and 2009, the rate of mobilization failure, defined as the inability to collect 5 × 10(6) CD34+ cells/kg following the first collection attempt, was 13%. By multivariate analysis, independent risk factors associated with mobilization failure included older age (P=0.04), lower platelet count (P=0.002) and use of single-agent G-CSF for mobilization (P<0.0001). When considering for outcome measurement stem cell collection efficiency measured by the number of CD34+ cells yielded per pheresis performed during first collection attempt, lower platelet count, use of single-agent G-CSF and older age were also associated with lower efficiency. In this population mobilized mostly with cyclophosphamide and G-CSF, the use of lenalidomide during induction was not associated with a lower stem cell collection efficiency by multivariate analysis. The data support the current International Multiple Myeloma Working Group guidelines recommending the use of cyclophosphamide and G-CSF based mobilization for patients previously exposed to lenalidomide.

Patterns of relapse and progression in multiple myeloma patients after auto-SCT: implications for patients' monitoring after transplantation.

Auto-SCT (ASCT) is widely used in first-line treatment of multiple myeloma (MM). However, most patients eventually relapse or have progression of disease (R/POD). Although precise knowledge of R/POD patterns would be important to generate evidence-based surveillance recommendations after ASCT, such data is limited in the literature, especially after introduction of the free light chain assay (FLCA). This retrospective study examined the patterns of R/POD after first-line ASCT in 273 patients, using established criteria. At the time of R/POD, only 2% of patients had no associated serological evidence of R/POD. A total of 85% had asymptomatic R/POD, first detected by serological testing, whereas 15% had symptomatic R/POD with aggressive disease, early R/POD and short survival, with poor cytogenetics and younger age identified as risk factors. Although occult skeletal lesions were found in 40% of asymptomatic patients tested following serological R/POD, yearly skeletal surveys and urine testing were poor at heralding R/POD. We found a consistent association between paraprotein types at diagnosis and R/POD, allowing informed recommendations for appropriate serological monitoring and propose a new needed criterion using FLCA for patients relapsing by FLC only. Our findings provide important evidence-based recommendations that strengthen current monitoring guidelines after first-line ASCT in MM.

Mechanism for the isotype dependence of antibody-mediated toxicity in Cryptococcus neoformans-infected mice.

Ab-based therapies have undergone a renaissance in recent years, but infusion-related reactions are a significant clinical problem. Administration of certain mAbs to Swiss Webster mice infected with Cryptococcus neoformans can result in acute lethal toxicity (ALT) characterized by cardiovascular collapse. The ability of a mAb to produce ALT is isotype dependent and occurs with IgG1 but not IgG3. To investigate this phenomenon, we measured spleen and liver cytokine responses and platelet-activating factor (PAF) content in mice given C. neoformans glucuronoxylomannan (GXM) followed by specific Ab of IgG1 or IgG3 isotype. We found no evidence to suggest that the differences in IgG1 and IgG3 toxicity were due to differences in chemokine or cytokine response. In contrast, liver and spleen tissue PAF content was significantly greater in mice IgG1. Furthermore, our results show differences in the response to IgG1- and IgG3-GXM complexes regarding: 1) macrophage-inflammatory protein-1alpha and monocyte chemoattractant protein-1 regulation, 2) splenic and hepatic PAF content, and 3) hepatic PAF content in infected mice. IgG1-associated ALT appears to be the result of greater production of PAF in response to IgG1-GXM complex formation. The results are consistent with the view that IgG1 and IgG3 interact with different Fc receptors. Our findings strongly suggest that the mechanism for Ab-mediated ALT is different from the cytokine release syndrome described after administration of other therapeutic mAbs.

Clearance and organ distribution of Mycobacterium tuberculosis lipoarabinomannan (LAM) in the presence and absence of LAM-binding immunoglobulin M.

Lipoarabinomannan (LAM) is a component of the mycobacterial surface which has been associated with a variety of deleterious effects on immune system function. Despite the importance of LAM to the pathogenesis of mycobacterial infection, there is no information available on its fate in vivo. In this study, we determined the pharmacokinetics and tissue distribution of exogenously administered LAM in mice. For measurements of serum and tissue LAM concentrations, we developed an enzyme-linked immunosorbent assay which used monoclonal antibodies of different isotypes to capture and detect LAM at concentrations of >/=0.4 microg/ml. Intravenous administration of LAM to mice resulted in transient serum levels with organ deposition in the spleen and in the liver. Immunohistochemical studies localized LAM to the spleen marginal zone macrophages and, to a lesser degree, to liver macrophages. When LAM was administered to mice previously given a LAM-binding immunoglobulin M (IgM), LAM was very rapidly cleared from circulation. In those mice, deposition of LAM in the spleen was significantly reduced while LAM deposition in the liver increased. Administration of LAM-binding IgM resulted in significant levels of IgM to LAM in bile consistent with an increased hepatobiliary excretion of LAM in the presence of specific antibody. Bile, liver extracts, and bile salts were found to rapidly inactivate the immunoreactivity of LAM. The results indicate that serum clearance and organ deposition of LAM in mice are affected by the presence of LAM-binding antibody and suggest a mechanism by which antibody could modify the course of mycobacterial infection.

Monoclonal antibody-mediated toxicity in Cryptococcus neoformans infection: mechanism and relationship to antibody isotype.

Antibody reagents represent an alternative for the therapy of human cryptococcosis, and monoclonal antibody 18B7 (IgG1) is a candidate for phase I trial in humans with cryptococcosis. However, antibody administration to mice with established Cryptococcus neoformans infection has been reported to produce acute lethal toxicity (ALT). The present study confirmed this phenomenon and investigated the mechanism of ALT. ALT was associated with hemoconcentration, hypotension, and circulatory collapse; however, toxicity could be prevented by platelet-activating factor inhibitor, rat antibody to Fc receptor, or IgM before IgG1. Significant isotype-specific differences were found in ALT, which can be interpreted as consistent with the hypothesis that there are distinct Fc receptors for murine IgG1 and IgG3. The IgM and IgG3 isotype preference in antibody responses to polysaccharide antigens in mice may translate to a lack of toxicity of antigen-antibody complexes during the course of infections with encapsulated pathogens.

Effect of immune mechanisms on the pharmacokinetics and organ distribution of cryptococcal polysaccharide.

Cryptococcus neoformans is an encapsulated opportunistic fungus that can cause chronic infections accompanied by high tissue levels of capsular polysaccharide (CPS). CPS or its major component, glucuronoxylomannan (GXM), was administered to mice, and whole-body and tissue levels were measured. The role of monoclonal antibody (MAb), complement, and CD4 T cells in GXM clearance was also examined. These studies demonstrate that CPS is cleared from the blood within days but is retained in the body for weeks; that MAbs of all isotypes examined promote GXM clearance; that MAb-mediated GXM deposition in liver, but not in spleen, is Fc-dependent; that complement enhances IgM-mediated GXM sequestration in liver but not spleen; and that CD4 T cells are not necessary for serum GXM clearance. The results have important implications for the eventual use of MAbs in treatment of cryptococcosis.

Characterization of a murine monoclonal antibody to Cryptococcus neoformans polysaccharide that is a candidate for human therapeutic studies.

The murine monoclonal antibody (MAb) 18B7 [immunoglobulin G1(kappa)] is in preclinical development for treatment of Cryptococcus neoformans infections. In anticipation of its use in humans, we defined the serological and biological properties of MAb 18B7 in detail. Structural comparison to the related protective MAb 2H1 revealed conservation of the antigen binding site despite several amino acid differences. MAb 18B7 was shown by immunofluorescence and agglutination studies to bind to all four serotypes of C. neoformans, opsonize C. neoformans serotypes A and D, enhance human and mouse effector cell antifungal activity, and activate the complement pathway leading to deposition of complement component 3 (C3) on the cryptococcal capsule. Administration of MAb 18B7 to mice led to rapid clearance of serum cryptococcal antigen and deposition in the liver and spleen. Immunohistochemical studies revealed that MAb 18B7 bound to capsular glucuronoxylomannan in infected mouse tissues. No reactivity of MAb 18B7 with normal human, rat, or mouse tissues was detected. The results show that both the variable and constant regions of MAb 18B7 are biologically functional and support the use of this MAb in human therapeutic trials.

Failure to induce rapid eye movement sleep by dark pulses in pigmented inbred rat strains.

Studies of albino Lewis rats, pigmented Brown Norway rats, and their F2 backcross progeny have demonstrated that the ability to trigger rapid eye movement (REM) sleep by turning off cage lights (dark pulses) is associated with albinism in these rat strains. Other studies have shown that pigmented inbred rats show REM sleep induction in the dark portion of short light:dark cycles or skin temperature changes. In the present study, these same pigmented breeds, Dark Agouti and hooded Long-Evans rats, were subjected to 5-min dark pulses and failed to show any evidence of REM sleep triggering. In fact, they showed trends towards REM sleep suppression during dark pulses. These results extend the finding that dark pulse triggering of REM sleep, readily evoked in albino rats, does not appear in pigmented rat strains.

Cross protection studies on Bordetella bronchiseptica in mice using an intracerebral challenge model.

Protective activities of heat-inactivated (60 degrees C for 30 min) merthiolate preserved Bordetella bronchiseptica and B. pertussis bacterins were compared in intraperitoneally immunized mice challenged intracerebrally (i.p./i.c.) or intraperitoneally (i.p./i.p.). In the i.p./i.c. assay (Kendrick test), a B. pertussis bacterin protected mice against challenge with B. pertussis 18-323, as well as against phase I cytotoxic and non-cytotoxic strains of B. bronchiseptica. A B. bronchiseptica bacterin, prepared from a phase I cytotoxic strain, gave protection against two phase I B. bronchiseptica strains, irrespective of their cytotoxin-production. A non-cytotoxic phase I strain of B. bronchiseptica elicited protection against the homologous strain only. Neither cytotoxic nor non-cytotoxic B. bronchiseptica strains protected mice challenged with B. pertussis 18-323. Vaccines prepared from phase III strains of B. bronchiseptica were not protective at all against any of the challenge strains. No such differences in the protective activities of the bacterins could be detected by the i.p./i.p. method. They seem to cross-protect equally well. The results indicate that the Kendrick test may be useful in testing potency of different B. bronchiseptica bacterins.