Hiding the road signs that lead to tumor immunity

Schaer et al. discuss mechanisms of immune evasions by tumors, including the recent finding that CCL2 nitrosylation prevents T cell infiltration into tumors

Self-antigen–specific CD8+ T cell precursor frequency determines the quality of the antitumor immune response

A primary goal of cancer immunotherapy is to improve the naturally occurring, but weak, immune response to tumors. Ineffective responses to cancer vaccines may be caused, in part, by low numbers of self-reactive lymphocytes surviving negative selection. Here, we estimated the frequency of CD8+ T cells recognizing a self-antigen to be <0.0001% (∼1 in 1 million CD8+ T cells), which is so low as to preclude a strong immune response in some mice. Supplementing this repertoire with naive antigen-specific cells increased vaccine-elicited tumor immunity and autoimmunity, but a threshold was reached whereby the transfer of increased numbers of antigen-specific cells impaired functional benefit, most likely because of intraclonal competition in the irradiated host. We show that cells primed at precursor frequencies below this competitive threshold proliferate more, acquire polyfunctionality, and eradicate tumors more effectively. This work demonstrates the functional relevance of CD8+ T cell precursor frequency to tumor immunity and autoimmunity. Transferring optimized numbers of naive tumor-specific T cells, followed by in vivo activation, is a new approach that can be applied to human cancer immunotherapy. Further, precursor frequency as an isolated variable can be exploited to augment efficacy of clinical vaccine strategies designed to activate any antigen-specific CD8+ T cells

Inhibition of Chemokine Expression by Adenovirus Early Region Three (E3) Genes

Adenoviruses (Ad) have a variety of immunoregulatory genes, many of which are clustered in a 3.5-kb segment of DNA known as early region 3 (E3). Ad E3 codes for proteins that downregulate surface expression of class I major histocompatibility antigens and also inhibit tumor necrosis factor alpha (TNF-α)- and Fas-induced cytolysis. We were interested in determining whether chemokine production or activity might also be inhibited by Ad E3 and we have studied this function in a human astrocytoma cell line, U373. Astrocytes constitute a part of the blood-brain barrier, and chemokines (IP-10, IL-8, MCP-1-4, and MIPs) expressed by them may contribute to leukocyte infiltration within the brain during inflammation. When U373 cells are activated by the proinflammatory molecule TNF-α, the increase in chemokine MCP-1, IL-8, and IP-10 transcripts is blocked by a recombinant Ad expressing the E3 genes under cytomegalovirus promoter control. Comparable Ads expressing green fluorescent protein in place of E3 have no effect on these chemokines. Ads also have been extensively studied as gene therapy vectors and most have a deletion of the E3 region to permit the insertion of larger fragments of foreign DNA. Our results suggest that construction of Ad vectors to include E3 expression cassettes will improve the efficacy and safety of such viral-based gene therapy protocols

Maintenance therapy and need for cessation studies in multiple myeloma: Focus on the future

With ten years of follow-up since the advent of the modern paradigm of combination induction therapy, consolidative autologous stem-cell transplant, and lenalidomide maintenance, median survival for multiple myeloma has increased to almost 50% at 10 years. Given this outlook, the overarching goal of maintenance therapy is to spare patients from the toxicities of aggressive or otherwise intrusive therapies while ideally extending survival or, at the least, extending progression-free survival or time until next treatment. This review will focus on the current landscape of maintenance therapies for multiple myeloma. The historical context and evidence for choice of agent, duration of treatment, and current strategies and ongoing trials will be discussed - as well as a focus on unmet needs. The case for studies investigating cessation of therapy and risk and response-adapted approaches will be underscored given that the current paradigm likely results in overtreatment for some patients

Significant Nationwide Variability in the Costs and Hospital Mortality Rates of Autologous Stem Cell Transplantation for Multiple Myeloma: An Analysis of the Nationwide Inpatient Sample Database

•Nationwide disparities exist in inpatient care for recipients of autologous hematopoietic stem cell transplantation (AHCT) performed to treat multiple myeloma.•The low-volume centers (<3 annual unweighted AHCTs) have higher mortality.•Patients admitted to private hospitals have lower costs and mortality.•Further study should be done to adjust for myeloma-specific factors. Autologous hematopoietic stem cell transplantation (AHCT) is the standard of care for eligible patients with multiple myeloma (MM). In this study, we explored disparities in hospital cost and in-hospital mortality among patients with MM who underwent AHCT. Data were obtained from the Nationwide Inpatient Sample database for 2005 to 2014. International Classification of Diseases, Ninth Edition, Clinical Modification diagnosis and procedure codes were used to identify patients. Hospitals were divided into quintiles according to the weighted volume of AHCTs performed in patients with MM. Multiple imputation with chained equation was used for missing data. Linear trend analysis of age- and sex-adjusted mortality, as well as inflation-adjusted hospital cost, was performed. Univariate regression screening followed by stepwise multivariate regression was performed for dependent variables, including mortality and inflation-adjusted hospital cost. Identified significant predictors underwent sensitivity analyses. Overall age- and sex-adjusted mortality rates and inflation-adjusted hospital costs decreased between 2005 and 2014; however, tremendous nationwide variability exists. Patients who underwent AHCT at very-low-volume hospitals (Q1) had significantly higher in-hospital mortality. Both geographic location and hospital type had impacted age- and sex-adjusted mortality rates and inflation-adjusted hospital costs. Despite an overall improvement in mortality and decreased cost of AHCT for patients with MM, nationwide variability in care exists. Further study is needed to identify correctable factors that contribute to the identified correlation

The Long PD-1 Receptor Binding Kinetics of Nivolumab May Increase Efficacy of Subsequent Therapy in Relapsed and Refractory Multiple Myeloma Patients

Abstract Introduction: Programmed cell death-1 (PD-1) signaling suppresses the antigen driven activation of T cells upon interaction with its ligands PD-L1 and PD-L2. The PD-1/PD-L1 axis is thought to mediate the resistance of multiple myeloma to conventional therapy (Tamura 2013; Paiva 2015). Nivolumab, a fully human IgG4 monoclonal PD-1 receptor-blocking antibody, has shown clinical activity in a variety of tumor types. Nivolumab has demonstrated a prolonged receptor binding kinetic lasting >100 days that may lead to an efficacy or toxicity signal in the post-treatment period. We therefore evaluated the response of patients with relapsed or refractory multiple myeloma to additional myeloma therapy received within 3 months of the end of nivolumab administration. Methods: The preliminary results of an open-label study that treated patients with relapsed or refractory multiple myeloma using a dose escalation design (1 mg/kg and 3 mg/kg) of nivolumab administered every 2 weeks have been reported previously (NCT01592370, Lesokhin et al., ASH 2014). Here we will report responses and safety data using standard criteria to the next line of therapy received immediately after nivolumab. Results: 8 patients with multiple myeloma from the original open label study were treated at Memorial Sloan Kettering Cancer Center. The disease characteristics and efficacy results are shown in the table. 1 of 8 patients (12.5%) experienced progression while on therapy manifested by development of an isolated plasmacytoma. The patient received radiation and then resumed and completed 97 weeks of therapy with nivolumab. He is currently off therapy without any evidence of disease at 48 weeks after cessation of nivolumab. 3 of 8 patients (37.5%) achieved a partial response to the next line of treatment after nivolumab. 2 of 8 patients (25%) who were exposed and refractory to immunomodulatory drugs (IMiDs) received single-agent, low-dose lenalidomide as the next line of therapy and achieved stable disease lasting approximately 100 days after cessation of nivolumab followed by disease progression. 1 of 8 patients (12.5%) experienced progressive disease despite the next line of therapy, and 1 of 8 patients (12.5%) received an experimental treatment as the next line of therapy and was therefore not evaluable. No new drug-related adverse events occurred in the 3 months after completing treatment with nivolumab. Overall, 6 out of 8 patients derived clinical benefit from post-nivolumab therapy, an unusually high response rate for this population. Conclusions: In a small cohort of patients with relapsed and refractory multiple myeloma, evaluation of response kinetics after cessation of nivolumab supports the notion that long PD-1 receptor binding kinetics may increase the efficacy of subsequent therapy without added toxicity. Larger studies are needed to confirm and expand our findings. Table. Patient Characteristics and Efficacy Age Sex ISS Cytogenetics Prior Lines ASCT IMiD E IMiD R Prot E Prot R Best Response to Nivolumab Next Line of Standard Therapy Best Response to Next Line 52 M 1 S 3 Y Y Y Y Y SD Carfilzomib, Cyclophosphamide, Dexamethasone PR 32 M 1 S 3 Y Y Y Y Y SD None* N/A 80 F 1 S 1 N Y N N N SD Lenalidomide PR 52 F 1 I 3 Y Y Y Y N SD Lenalidomide SD 62 M 1 H 1 Y Y N Y N PD Cyclophosphamide, Bortezomib, Dexamethasone PR 58 M 2 S 5 Y Y Y Y Y PD Lenalidomide SD 57 F 1 S 3 Y Y N Y Y PD None^ N/A 59 F 1 S 3 Y Y Y Y Y PD Lenalidomide, Bortezomib, Dexamethasone PD ISS=international staging system; S=standard cytogenetics; I=intermediate cytogenetics; H=high risk cytogenetics; ASCT=autologous stem cell transplant; IMiD E=IMiD exposed; IMiD R=IMiD refractory; Prot E=proteosome exposed; Prot R=proteosome refractory; PD=progressive disease; SD=stable disease; PR=partial response *Patient completed 97 weeks of nivolumab and continues untreated without any evidence of disease at 48 weeks after cessation of therapy ^Patient received treatment on an experimental protocol Disclosures Funt: Kite Pharma: Equity Ownership. Off Label Use: Nivolumab is FDA approved for use in patients with metastatic melanoma but not in patients with multiple myeloma. . Page:Celgene: Consultancy. Landgren:Bristol-Myers Squibb: Honoraria; Celgene: Consultancy; BMJ Publishing: Consultancy; Bristol-Myers Squibb: Consultancy; BMJ Publishing: Honoraria; Medscape: Consultancy; Medscape: Honoraria; Celgene: Honoraria; International Myeloma Foundation: Research Funding; Onyx: Honoraria; Onyx: Research Funding; Onyx: Consultancy. Borrello:Celgene: Research Funding. Lesokhin:Bristol Myers Squibb: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Aduro: Consultancy; Genentech: Research Funding; Efranat: Consultancy

WT1 heteroclitic epitope immunization following autologous stem cell transplantation in patients with high-risk multiple myeloma (MM)

8016 Background: Host T-cells mount immune responses (IR’s) against Wilms tumor 1 (WT1) in A*0201 + MM pts through formation of WT1 peptide fragment (RMFPNAPYL)/HLA-A*0201 complex. We report initial results from MM pts immunized with the WT1 heteroclitic peptide mixture galinpepimut-S (GPS) after autoSCT. Methods: 16 MM pts underwent autoSCT with melphalan conditioning followed by (f/b) lenalidomide maintenance starting 3 months (mos) post-SCT. 13/16 pts presented with high-risk (HR) cytogenetics [t(4;14), t(14;16), del17p, 1q21/25 gain and/or del13q]. GPS was administered with montanide s.c. starting 2 wks post-SCT and q.2 wks thereafter x 6 initial doses f/b boosters q.4 wks x 6 additional doses. GM-CSF was given on days -2 and 0 of each cycle. GPS consisted of 4 peptides: WT1-A1: Y*MFPNAPYL; 427-L (long): RSDELVRHHNMHQRNMTKL; 331-L: PGCNKRYFKLSHLQMHSRKHTG, and 122A1-L: SGQAY*MFPNAPYLPSCLES. 2 of the 4 peptides were mutated at a single residue (*) to induce stronger HLA-binding/reduce tolerance. WT1-specific IR’s were assessed by intracellular IFN-g analyses post-challenge with PBMC’s pulsed with a ‘total pool’ of overlapping 15mers along the entire WT1 protein; or each of the 4 WT1 peptides in GPS; or the non-mutated (native) WT1 peptides corresponding to the 2 heteroclitic sequences. Results: 16 pts; median follow-up: 18 mos (range: 5-31 mos) for survivors; median age: 61.6 y. Overall survival (OS) and progression-free survival (PFS) (95% CI) at 18 mos: 0.88 (0.73-0.99) and 0.62 (0.42-0.97) respectively. Current median PFS: 23.6 mos (15.2 - not reached). No >G2 systemic side effects were observed, however, all pts developed local nodularity at the site of injections which resolved over 2 – 6 wks. Both CD8+ and CD4+ IR’s could be detected at various levels and were induced not only against the heteroclitic peptides (within GPS), but also against the corresponding native WT1 peptide sequences as well as the ‘total pool’ of WT1-derived overlapping peptides. Conclusions: Administration of the novel WT1 heteroclitic peptide immunizer GPS post auto SCT demonstrates favorable safety profile along with encouraging mPFS of currently 23.6 mos in this high-risk MM population. Clinical trial information: NCT01827137

Efficacy and Risk Factors Analysis of Upfront Autologous Stem Cell Mobilization Using Plerixafor and Granulocyte-Colony Stimulating Factor (GCSF) in Patients with Multiple Myeloma

Abstract Background: G-CSF with or without cyclophosphamide has been commonly used in multiple myeloma (MM) for stem cell (SC) collection prior to autologous stem cell transplantation (ASCT). Several risk factors including age, prolonged exposure to lenalidomide, and low platelet count are associated with suboptimal stem cell harvest. Plerixafor selectively and reversibly binds to the chemokine receptor CXCR4 and blocks its interaction with stromal cell-derived factor-1α. This drug was approved by the FDA for stem cell mobilization in MM, based on phase III studies demonstrating the superiority of plerixafor and G-CSF over G-CSF alone in achieving a predetermined target yield of 6 × 106CD34+ cells/kg collected in < 2 phereses; however, this outcome is not clinically relevant. The purpose of this retrospective study is to examine the SC mobilization efficiency associated with plerixafor using a more clinically relevant outcome, and to identify risk factors associated with poor SC mobilization, including the potential impact of prior exposure to lenalidomide-containing regimens. Patients and methods: This retrospective study examined MM patients mobilized with plerixafor and G-CSF upfront as part of initial therapy at Memorial Sloan Kettering Cancer Center between 4/1/2009 and 8/1/2013. Baseline characteristics examined included age, race, gender, platelet count, WBC count, and marrow plasmacytosis prior to mobilization. Treatment characteristics examined included type of induction regimen (distinguishing regimens containing lenalidomide only, bortezomib only, or both), number of cycles received, time between last chemotherapy and SC mobilization, time between start of treatment and SC collection, and prior radiation. The primary endpoint was the rate of SC collection success, defined as the ability to collect at least 5 x 106CD34+ cells/kg during the first set of phereses, which would be sufficient for two ASCT. The secondary endpoint was SC collection efficiency, measured by the number of CD34+ cells yielded per pheresis performed during the first set of stem cell collection. Linear regression was used to examine the univariate effect of baseline and treatment variables on SC collection efficiency. Variables significant at the 0.05 level were entered into a multivariable model. Results: A total of 138 MM patients were mobilized with plerixafor and G-CSF before proceeding to stem cell collection. The rate of SC collection success was 92.8%. Due to this high success rate, we could not identify independent risk factors associated with poor SC mobilization. When considering SC efficiency as outcome, the average efficiency for the entire cohort was 7.25 x 10^6 CD34+ cells/kg/pheresis. Increased age (p=0.005), shorter time between treatment start and SC collection (p=0.05), higher number of cycles received during induction treatment (p=0.042), lower platelet count (p=0.009) and lower WBC prior to G-CSF (p=0.01), and exposure to lenalidomide only (p=0.011) were all identified as risk factors by univariate analysis. Only lower WBC prior to GCSF (p=0.009) maintained statistical significance after multivariate analysis. Conclusions: This retrospective study shows that plerixafor is a highly effective agent for SC mobilization and collection in MM patients, with only few patients failing to achieve the target collection regardless of baseline or treatment characteristics including prior lenalidomide exposure. However, we identified WBC prior to G-CSF administration as a predictor of SC collection efficiency. These results provide strong support to the upfront use of plerixafor and G-CSF for SC mobilization in MM patients. A cost analysis is currently in progress comparing this SC collection modality with other conventional means currently being employed in patients with MM. Disclosures No relevant conflicts of interest to declare