Page 1 TITLE: A Phase II Trial of Vaccination with Dendritic Cell (DC)/Myeloma Fusions in Combination with Nivolumab in Patients with Relapsed Multiple Myeloma NCT Number: NCT03782064 Protocol Date: 10/17/2020 DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 2 DF/HCC Protocol #: 18-280 TITLE: A Phase II Trial of Vaccination with Dendritic Cell (DC)/Myeloma Fusions in Combination with Nivolumab in Patients with Relapsed Multiple Myeloma Coordinating Center: Beth Israel Deaconess Medical Center *Principal Investigator (PI): Jacalyn Rosenblatt, MD Beth Israel Deaconess Medical Center jrosenb1@bidmc.harvard.edu Other Investigators: David Avigan, MD Beth Israel Deaconess Medical Center davigan@bidmc.harvard.edu Responsible Research Nurse: Study Coordinator: Chelsey Gibson Brendan Mackey Beth Israel Deaconess Medical Center Beth Israel Deaconess Medical Center 617-667-1957 617-667-9923 eknudsen@bidmc.harvard.edu bmackey@bidmc.harvard.edu IND #: BB8184 IND Sponsor: David Avigan, MD Protocol Type / Version # / Version Date: Amendment 10 / October 17, 2020 DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 3 TABLE OF CONTENTS 1. OBJECTIVES ......................................................................................................................5 1.1 Study Design ............................................................................................................5 1.2 Primary Objectives...................................................................................................5 1.3 Secondary Objectives...............................................................................................5 2. BACKGROUND .................................................................................................................5 2.1 Therapeutic approaches in Multiple Myeloma ........................................................5 2.2 Vaccine Therapy for Multiple Myeloma .................................................................6 2.3 Vaccination with DC/Myeloma fusion cells following autologous transplant ................................................................................................................6 2.4 Checkpoint Blockade ...............................................................................................7 2.5 Nivolumab................................................................................................................7 2.6 Checkpoint Blockade in Myeloma...........................................................................8 2.7 Rationale ..................................................................................................................8 2.8 Correlative Studies Background ............................................................................10 3. PARTICIPANT SELECTION ...........................................................................................11 3.1 Eligibility Criteria ..................................................................................................11 3.2 Exclusion Criteria ..................................................................................................11 3.3 Eligibility Prior to Vaccination with DC/MM fusions and nivolumab..................13 3.4 Inclusion of Women and Minorities ......................................................................13 4. REGISTRATION PROCEDURES ...................................................................................13 4.1 General Guidelines for DF/HCC Institutions ........................................................13 4.2 Registration Process for DF/HCC Institutions .......................................................13 5. TREATMENT PLAN ........................................................................................................13 5.1 Evaluations Prior to Enrollment.............................................................................13 5.2 Tumor Collection ...................................................................................................14 5.3 Dendritic Cell Collection .......................................................................................14 5.4 SOC Anti-Myeloma Bridging Therapy .................................................................14 5.5 Evaluation Prior to Initiation of Immunotherapy...................................................14 5.6 Day 1 of Cycles 1-3 (+/- 3 days) ............................................................................15 5.7 Day 15 of Cycles 1-3 (+/- 3 days) ..........................................................................16 5.8 Day 1 of Cycle 4 (+/- 3 days) ................................................................................16 5.9 Day 1 of Cycles 4-6 (+/- 3 days) ............................................................................16 5.10 Day 15 of Cycles 4-6 (+/- 3 days) ..........................................................................16 5.11 Follow Up ..............................................................................................................17 5.12 Agent Administration.............................................................................................18 5.13 General Concomitant Medication and Supportive Care Guidelines ......................19 5.14 Criteria for Taking a Participant Off Protocol Therapy .........................................19 5.15 Criteria for Taking a Participant Off Study ...........................................................19 6. DOSING DELAYS/DOSE MODIFICATIONS ...............................................................19 DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 4 6.1 Dose Delays ...........................................................................................................20 6.2 Management of Nivolumab-Related Infusion Reactions .......................................21 6.3 Management of Other Nivolumab-Related AEs ....................................................21 6.4 Management of DC/MM Vaccine Site Reaction ...................................................22 7. Identification of Treatment Limiting Toxicities ................................................................22 8. ADVERSE EVENTS: LIST AND REPORTING REQUIREMENTS ............................22 8.1 Expected Toxicities ................................................................................................22 8.2 Adverse Event Characteristics ...............................................................................23 8.3 Adverse Event Reporting .......................................................................................24 8.4 Reporting to the Food and Drug Administration (FDA) .......................................25 8.5 Reporting to the Institutional Biosafety Committee (IBC) ....................................25 8.6 Reporting to Hospital Risk Management ...............................................................25 8.7 Routine Adverse Event Reporting .........................................................................25 9. PHARMACEUTICAL INFORMATION ..........................................................................25 9.1 Nivolumab..............................................................................................................25 9.2 DC/MM Fusion Vaccine ........................................................................................27 9.3 GM-CSF .................................................................................................................28 10. BIOMARKER, CORRELATIVE, AND SPECIAL STUDIES ........................................28 10.1 Correlative Studies .................................................................................................28 10.2 Sample Collection time points ...............................................................................29 11. STUDY CALENDAR .......................................................................................................31 12. MEASUREMENT OF EFFECT........................................................................................34 12.1 Definition of Disease Status...................................................................................34 12.2 Response Categories ..............................................................................................34 13. DATA REPORTING / REGULATORY REQUIREMENTS ...........................................36 13.1 Data Reporting .......................................................................................................36 13.2 Data Safety Monitoring..........................................................................................36 14. STATISTICAL CONSIDERATIONS...............................................................................36 14.1 Study Design ..........................................................................................................37 15. PUBLICATION PLAN .....................................................................................................38 REFERENCES ..............................................................................................................................39 APPENDIX A PERFORMANCE STATUS CRITERIA ..................................................40 APPENDIX B: Dose Modifications for Nivolumab-related AEs..................................................41 DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 5 1. OBJECTIVES 1.1 Study Design The study is a phase II study to evaluate vaccination with DC/myeloma fusions/GM-CSF and nivolumab in patients diagnosed with relapsed multiple myeloma previously treated with a proteasome inhibitor, IMiD, and anti-CD38 mAb therapy. Patients meeting initial eligibility will be enrolled and vaccine production will be initiated via the harvesting of autologous tumor cells and generation of DCs from adherent mononuclear cells. During the period of vaccine generation, patients will undergo therapy with 1-2 cycles of standard of care therapy. Patients without disease progression will then undergo monthly vaccination with DC/MM fusions for cycles 1, 2, and 3 in conjunction with nivolumab administered on day 1 and 15 and will then receive nivolumab alone for 3 addition cycles, for a total of 6 cycles of treatment. 1.2 Primary Objectives 1.2.1 Primary Immunologic Endpoint The primary endpoint is to define the immunologic response to nivolumab and the DC/MM fusion vaccine with respect to the induction of myeloma-specific immunity in patients with relapsed disease after prior proteasome inhibitor, IMiD, and anti-CD38 mAb therapy. Specifically, we will quantify the expansion of treatment-induced myeloma-specific T cells in the circulation as measured by pre-therapy and peak post-treatment levels of CD4 and CD8 T cells expressing IFNγ following ex-vivo exposure to autologous tumor lysate. The percentage of patients achieving at least a 3 and 10-fold expansion of myeloma-specific T cells will be determined. 1.3 Secondary Objectives 1.3.1 Secondary Immunologic Endpoints We will determine the effect of therapy on the percent of marrow-infiltrating myeloma-specific T cells as measured by pre-therapy and peak post-treatment levels of CD4 and CD8 T cells expressing IFNγ following ex vivo exposure to autologous tumor lysate. We will also quantify T cells specific to shared myeloma antigens potentially including MUC1, NY-ESO, PRAME, Survivin, XPB-1, SOX2, and WT1 by pentamer analysis. Assessment of the immune landscape will consist of quantifying T cell subsets in the circulation and marrow, presence of MDSCs, PD-1 expressing T cells, Tregs, and immunoregulatory microRNAs and will be correlated with immunologic response. 1.3.2 Secondary Clinical Endpoints To determine the clinical response and safety of nivolumab and the DC/MM fusion vaccine in patients with relapsed disease. The percentage of patients achieving complete, very good partial and partial response will be quantified. Minimal residual disease (MRD) status will be determined. Progression free survival (PFS) will be assessed. 2. BACKGROUND 2.1 Therapeutic approaches in Multiple Myeloma Despite major recent advances in therapeutic options for patients with multiple myeloma (MM), curative outcomes remain elusive. While the introduction of IMIDs, proteasome inhibitors, and antibody-mediated therapies have dramatically improved progression free and overall survival in MM patients, progressive resistance to biologic agents ultimately develops and often results in disease-associated mortality.1 Novel approaches are needed to improve patient outcomes. Cancer therapeutics has undergone a dramatic change with the observation that cellular DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 6 immunotherapy results in sustained disease response in a subset of patients with previously incurable disease.2 This approach potentially harnesses native immunity to provide specific targeting of tumor cells and the development of memory responses critical to prevent relapse. 2.2 Vaccine Therapy for Multiple Myeloma Immune therapy has emerged as a leading area of cancer therapeutics due to its potential to recruit multiple effectors that broadly target malignant cells and overcome mechanisms of resistance.3,4 Multiple myeloma (MM) is characterized by the loss of critical mediators of immune surveillance, resulting in the suppression of antigen- presenting and effector cell function and the development of an immunologic milieu that fosters disease progression.5–7 We have developed a tumor vaccine in which patient-derived myeloma cells are fused with autologous dendritic cells (DCs), such that a broad array of myeloma antigens are presented in the context of DC- mediated costimulation.8–10 In diverse tumor models that include MM, vaccination of animals with DC/tumor fusions results in protection from an otherwise lethal challenge of malignant cells and, more significantly, eradication of disease in the setting of advanced metastatic involvement.11 In a phase I study, 17 patients with advanced myeloma (median of 4 prior regimens) underwent vaccination with DC/MM fusions in conjunction with 4 days of GM-CSF administered at the vaccine site. In this study, MM cells were isolated from bone marrow aspirates and fused with autologous DCs generated from adherent mononuclear cells cultured with GM-CSF, IL-4, and TNFα.8 Vaccine production was successful in all patients and was well-tolerated without evidence of clinically significant autoimmunity. Vaccination resulted in a mean 10-fold expansion of CD4 and CD8 myeloma-specific T cells, as determined by the percentage of cells expressing IFNγ in response to ex-vivo exposure to autologous tumor lysate. Similarly, vaccination resulted in the development of myeloma-specific antibody responses as documented by SERAX analysis.8 2.3 Vaccination with DC/Myeloma fusion cells following autologous transplant Vaccination with DC/Myeloma fusion cells following autologous transplant is associated with potent immune response and conversion from PR to CR in a subset of patients.10 We completed a clinical trial in which MM patients were vaccinated with DC/MM fusion cells in conjunction with autologous transplantation (ASCT).8,10 In the first cohort of the study, twenty-four patients received serial vaccinations following post-transplant hematopoietic recovery. A second cohort of 12 patients received a pre-transplant vaccine followed by post-transplant vaccinations. Vaccine preparation was successful in all patients. Mean yield of the DC and MM cells was 1.74 x 108 and 6.5 x 107 cells, respectively. Mean fusion efficiency, as determined by the percentage of cells that co-expressed unique DC (CD80, CD86, and/or CD83) and MM (CD38 and/or CD138) antigens, was 38%. The mean dose administered was 3.6 x 106 fusion cells. Mean viability of the DC, myeloma, and fusion preparations was 87%, 87%, 79%, respectively. The DC/MM fusion preparations exhibited potent antigen presenting capacity, as evidenced by their stimulation of allogeneic T cell proliferation, with a mean stimulation index of 36.6, similar to that observed with the DC preparation prior to fusion (mean stimulation index of 52.3). In contrast, the unfused myeloma cells demonstrated minimal capacity for T cell stimulation (mean stimulation index of 13.7). All vaccine-associated toxicities were of grade I-II intensity. The most common toxicity was erythema and induration at the vaccine injection site associated with T cell infiltration on biopsy. The other common side effects were transient pruritus, rash, fatigue, fever, and myalgias. One patient had a transiently elevated ANA level without clinical evidence of autoimmunity. One patient developed transient grade 2 leukopenia, but no evidence of graft compromise was observed following vaccination. Consistent with prior reports, the post-transplant period was associated with the relative suppression of general measures of cellular immunity as manifested by decreased T cell proliferative responses to mitogen or recall antigens. In contrast, the period of post-transplant lymphopoietic reconstitution was associated with the expansion of myeloma-specific T cells that was further boosted following vaccination, as determined by percentage of CD4+ and CD8+ T cells expressing IFNγ in response to ex-vivo exposure to autologous tumor lysate. In the first cohort that received only post-transplant vaccination, the mean log10-fold increase in myeloma-specific CD4+ T cells from pre- mobilization to post-transplant and from pre-mobilization to peak post-vaccination was 3.55 (95% CI 0.81;15.49) and 10.72 (95% CI 3.89;29.51), respectively. Similarly, the mean log10-fold increase in myeloma-specific CD8+ T cells from pre-mobilization to post-transplant and from pre-mobilization to peak post-vaccination was 6.76 (95% CI 3.02;15.49) and 11.48 (95% CI 4.17;32.36), respectively. A smaller subset of patients underwent a single pre- DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 7 transplant vaccination followed by post-transplant boosting. Of note, no difference in peak levels of CD4+ or CD8+ circulating myeloma-specific T cells was observed between the cohort receiving a pre-transplant vaccine and that undergoing post-transplant vaccination alone (p=0.185 and p=0.689, respectively). For the entire study population, the mean log10-fold increase in myeloma-specific CD4+ T cells from pre-mobilization to post-transplant and from pre-mobilization to peak post-vaccination was 3.55 (95% CI 1.58;8.13) and 9.55 (95% CI 5.37;16.98), respectively. The mean log10 fold increase in myeloma-specific CD8+ T cells from pre-mobilization to post-transplant and from pre-mobilization to peak post-vaccination was 4.37 (95% CI 2.40;7.76) and 8.32 (95% CI 4.68;15.14), respectively. Notably, vaccination was associated with the expansion of T cells targeting the myeloma-specific antigen, MUC1, as determined by tetramer analysis. In a cohort of patients who were HLA-A2, the median percentage of MUC1- specific T cells was 0.12 pre-transplant and increased to 1.84 at 3 months after completion of vaccination (p<0.05), representing a median fold increase of 17.5. The expansion of T cells targeting MUC1 in response to vaccination is of particular interest, as we have identified a population of CD34+/MUC1+ cells in the bone marrow of patients with myeloma that demonstrate myeloma-initiating capacity. Seventy-eight percent of patients achieved a CR or VGPR (47% CR/nCR; 31% VGPR). Thirty-one percent achieved a CR/nCR in the early post-transplant period, whereas an additional 17% (6 patients: 4 from VGPR, 2 from PR) achieved CR/nCR as best response only after day 100 post- transplant and after undergoing vaccination. The presence of late responses several months after ASCT is consistent with an impact of vaccine therapy on post-transplant residual disease. 2.4 Checkpoint Blockade A remaining challenge to develop sustained and clinically effective immune therapy for myeloma involves overcoming the immunosuppressive milieu characteristic of the tumor microenvironment.12 A critical component of this tolerizing environment is the upregulation of negative costimulatory molecules such as programmed death receptor 1 (PD-1) that induced a state of T cell exhaustion.3,13,14 Two ligands specific for PD-1 have been identified: PD-ligand 1 (PD-L1, also known as B7-H1 or CD274, expressed on tumor, antigen-presenting cells [APCs], and dendritic cells [DCs]) and PD-L2 (also known as B7-DC or CD273, expressed on endothelial cells). The interaction of PD-1 with PD-L1 and PD-L2 results in negative regulatory stimuli that down-modulate the activated T-cell immune response through SHP-1 phosphatase.15 In health, ligation of PD-1 is associated with protection from autoimmune sequelae of immune overstimulation. For example, PD-1 knockout mice develop strain-specific lupus- like glomerulonephritis (C57BL/6)16 and cardiomyopathy (BALB/c)17. In the setting of malignancy, upregulation of PD-L1 on tumor cells and ligation of PD-1 on tumor associated lymphocytes results in a state of immune tolerance and escape facilitating tumor growth. In contrast, blockade of the PD-1/PD-L1 pathway has been associated with dramatic and sustained disease responses in a subset of patients with malignancy including malignant melanoma, Hodgkin disease, renal, lung, bladder, and head and neck cancer.2,18 2.5 Nivolumab Nivolumab (BMS-936558, MDX-1106, and ONO-4538) is a fully human monoclonal immunoglobulin G4 (IgG4) antibody (HuMAb) that is specific for human programmed death-1 (PD-1, cluster of differentiation 279 [CD279]) cell surface membrane receptor. PD-1 is a negative regulatory molecule that is expressed transiently following T- cell activation and on chronically stimulated T cells characterized by an “exhausted” phenotype. Nivolumab binds to cynomolgus monkey PD-1 but not mouse, rat, or rabbit molecules. Clinical activity of nivolumab has been observed in patients with melanoma, non-small cell lung cancer (NSCLC), renal cell carcinoma (RCC), and recently in hematologic malignancies. This clinical experience has demonstrated that endogenous immune responses can mediate effective tumor regression and/or improved survival even in patients with large volume tumors resistant to other forms of therapy. It is not yet clear what factors with respect to the tumor cells, their surrounding microenvironment, and the nature of immune dysregulation are determinative of response to the class of checkpoint inhibitors. 2.5.1 Nonclinical Development of Nivolumab In intravenous (IV) repeat-dose toxicology studies in cynomolgus monkeys, nivolumab alone was well tolerated (Investigator Brochure, 2015). Nivolumab bound specifically to PD-1 (and not to related members of the CD28 family such as CD28, ICOS, CTLA-4, and BTLA) with a Kd = 3.06 nM. A surrogate rat anti-mouse PD-1 antibody (4H2) was derived and expressed as chimeric IgG1 murine antibody. Antitumor activity was seen for several tumor DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 8 models, including colon carcinoma and fibrosarcoma. 2.5.2 Clinical Development of Nivolumab Nivolumab is being evaluated as monotherapy and in combination with cytotoxic chemotherapy, other immunotherapy (such as ipilimumab), anti-angiogenesis therapy, and targeted therapies in completed and ongoing BMS-sponsored clinical trials in NSCLC, melanoma, RCC, hepatocellular carcinoma (HCC), gastrointestinal (GI) malignancies including microsatellite instability (MSI) in colorectal cancer, and triple- negative breast cancer (TNBC) with an expanding group of indications in hematologic malignancies (Investigator Brochure, 2015). Investigator-sponsored trials (ISTs) of nivolumab in combination with a peptide vaccine in melanoma are being conducted in the adjuvant setting and advanced disease. 2.5.3 Pharmacokinetics Pharmacokinetics (PK) of nivolumab was linear in the range of 0.3 to 10 mg/kg, with dose-proportional increases in maximum serum concentration (Cmax) and area under the concentration-time curve from time zero to infinity (AUC0-∞), with low to moderate inter-subject variability observed at each dose level (Investigator Brochure, 2015). Clearance of nivolumab is independent of dose in the dose range (0.1 to 10 mg/kg) and tumor types studied. Body weight normalized dosing showed approximately constant trough concentrations over a wide range of body weights. The mean terminal elimination half-life of BMS-936558 is 17 to 25 days consistent with the half-life of endogenous IgG4. 2.5.4 Efficacy In a phase 1 (1, 3, and 10 mg/kg nivolumab doses) dose-escalation study, the 3 mg/kg dose was chosen for expanded cohorts. Among 236 patients, objective responses (ORs) (complete or partial responses [CR or PR]) were seen in NSCLC, melanoma, and RCC. Ors were observed at all doses.18 Median OS was 16.8 months across doses and 20.3 months at the 3 mg/kg dose. Median OS across all dose cohorts was 9.2 months and 9.6 months for squamous and non-squamous NSCLC, respectively.19 In the RCC cohort, median duration of response was 12.9 months for both doses with 5 of the 10 responses lasting ≥1 year. 2.5.5 Toxicology A maximum tolerated dose (MTD) of nivolumab was not defined.18 Serious adverse events (SAEs) occurred in 32 of 296 patients (11%) similar to the immune-related inflammatory events seen with ipilimumab: pneumonitis, vitiligo, colitis, hepatitis, hypophysitis, and thyroiditis (with noted pulmonary toxicity resulting in 3 deaths. Renal failure, symptomatic pancreatic and DM, neurologic events, and vasculitis have also been reported.). 2.6 Checkpoint Blockade in Myeloma PD-1 expression is upregulated on T-cells isolated from patients with MM,14,20,21 suggesting that this pathway is of importance in mediating the immunosuppressive state in this patient population. However, PD-1 blockade has demonstrated minimal single agent activity in MM due to the lack of the intrinsic anti-tumor immunity in this setting.3,22,23 Efforts are underway to assess the activity of combination therapy with immunomodulatory agents and PD-1 antibody.24 Phase II studies demonstrated that PD-1 blockade in conjunction with IMID therapy resulted in clinical activity in a subset of patients with advanced disease who were refractory to single agent therapy with IMIDs. However, a randomized trial demonstrated increased morbidity and mortality was noted in patients treated with combination IMID therapy and PD-1 blockade. We postulate that the DC/MM fusion vaccine will act synergistically with checkpoint blockade by inducing the expansion of myeloma specific T cells that can be further activated by exposure to checkpoint blockade. Indeed, preclinical studies from our laboratory demonstrated that PD-1 blockade enhances T-cell response to DC/MM fusions in vitro.25 2.7 Rationale DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 9 MM is associated with immune suppression, including defects in antigen presentation and effector cell function that are thought to play a role in disease progression. Although the outcomes for myeloma patients have improved greatly over the past decade, the majority of patients relapse even after autologous stem cell transplant and post- transplant maintenance therapy with lenalidomide. We have demonstrated that vaccination with DC-MM fusions induces the expansion of myeloma reactive T cells and is associated with the conversion of partial to complete responses following high dose chemotherapy with stem cell rescue. We are currently conducting a national randomized multicenter trial under the auspices of the CTN cooperative oncology group, to assess the clinical and immunologic impact of vaccination with lenalidomide maintenance as compared to maintenance alone in myeloma patients undergoing autologous stem cell transplantation. In a phase 1 trial published in 2011, we previously studied the role of personalized DC/MM fusion vaccination in the setting of relapsed MM. In this patient experience, we did observe an encouraging immunologic signal. However, only a subset of these relapsed MM patients had stable disease post-vaccination and no patient demonstrated a reduction in disease burden.8 For this reason, we postulate that in the relapsed MM disease setting, the combination of vaccination along with a second immunologic agent may yield disease response in addition to immunologic activation against MM. In the present proposal, we hypothesize that the efficacy of checkpoint blockade in myeloma is dependent on the initial expansion of myeloma-reactive T cells in the immune repertoire that can then be further activated and expanded in the context of nivolumab therapy. We propose a clinical trial to examine the toxicity, immunologic effect and clinical response of nivolumab administered in conjunction with the DC/MM vaccine, as vaccination alone in this patient population has not previously yielded clinical disease response. We hypothesize that the study will illuminate the nature of the immunologic response to a therapeutic strategy that incorporates vaccine-mediated expansion of myeloma specific T cell immunity and antibody-mediated targeting of negative checkpoints that will alter the tumor microenvironment and favor the generation of a productive immune response targeting myeloma cells. DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 10 2.8 Correlative Studies Background 2.8.1 Impact of therapy on the immunologic response in the peripheral blood and bone marrow The primary immunologic endpoint is to define the immunologic response to nivolumab and the DC/MM fusion vaccine with respect to the induction of peripheral blood myeloma-specific immunity in patients with relapse disease after prior proteasome inhibition, IMiD, and anti-CD38 mAb therapy. Specifically, we will compare the expansion of treatment-induced myeloma-specific T cells in the circulation as measured by pre-therapy and peak post-treatment levels of CD4 and CD8 T cells expressing IFNγ following ex-vivo exposure to autologous tumor lysate. Similarly, as a secondary endpoint and correlative study, we will quantify the percentage of myeloma-reactive lymphocytes in the bone marrow prior to cycles 1, 3, 6 and at the off-treatment time. The expansion of myeloma-specific T cells in the circulation and bone marrow will be calculated individually for each patient so that the specific baseline levels prior to vaccination will serve as an internal control value for each patient. To control for intrinsic variability of the assay, samples are cryopreserved and all time points are analyzed in a single experiment. To control for nonspecific reactivity against normal marrow elements, T cell expression of IFNγ will be measured following pulsing with lysate from CD38- BMMCs (when feasible). We will determine the mean fold increase in myeloma- specific T cells and the percentage of patients demonstrating 3 and 10 fold threshold increases in response to vaccination in the circulation and the bone marrow. We hypothesize that patients will demonstrate enhanced myeloma-specific immunity following exposure to vaccine plus nivolumab as compared to the pre-treatment time point. In a prior study, we observed that patients with multiple myeloma exposed to a MM/DC fusion vaccine had a mean log10-fold increase in myeloma-specific CD4+ T cells from pre-mobilization to post-transplant and from pre-mobilization to peak post-vaccination was 3.55 (95% CI 1.58;8.13) and 9.55 (95% CI 5.37;16.98), respectively. The mean log10 fold increase in myeloma-specific CD8+ T cells from pre-mobilization to post-transplant and from pre-mobilization to peak post-vaccination was 4.37 (95% CI 2.40;7.76) and 8.32 (95% CI 4.68;15.14), respectively.8,10 Similarly, in an early phase clinical trial of AML patients receiving AML/DC fusion vaccination following a chemotherapy-induced remission, we also observed enhanced leukemia-specific immunity as evidenced by increased circulating lymphocytes targeting leukemia cells.26 2.8.2 Effect of treatment on circulating T cells binding the MUC1, NY-ESO, Survivin, PRAME, WT1 tetramers in HLA-A2.1 patients We have previously observed enhanced antigen-specific reactivity in patients treated with personalized dendritic cell fusion vaccine therapy.10,26 We will examine antigen-specific reactivity by tetramer analysis in prior to and after exposure to the vaccine and nivolumab in HLA-A2.1 positive patients. This assay utilizes tetrameric proteins to detect and quantify T-cells that are specific for a given antigen within a peripheral blood sample. We hypothesize that patients treated with the combination of vaccine and nivolumab will elicit immune-specific responses against myeloma cells and thereby, we will observe increased T cells against common myeloma antigens including WT-1 and MUC-1. Functional characteristics of the pentamer positive cells will be determined by quantifying expression of IFNγ, granzyme B, IL-4, and IL-10 expression by intracellular FACS staining. 2.8.3 Immune microenvironment including T cell subsets, T cell checkpoint receptors and myeloid-derived suppressor cells (MDSCs) We plan on quantifying T cell subsets, T cell checkpoint receptors, and MDSCs via flow cytometry. Bone marrow aspirate and peripheral blood samples will be obtained prior to and after initiating immunotherapy and the microenvironment will be assessed with respect to the presence of Tregs, PD-1 expressing T cells, central memory (CD4/CD62L/CD27), effector memory (CD4/CD62L/CD27), and naïve T cells and granulocytic (CD11B+ CD33+ HLADRLOW/ CD15+) and monocytic (CD11B+ CD33+ HLADRLOW/ CD15-) MDSCs. We hypothesize that exposure to vaccine and PD-1 blockade with nivolumab will shift T cells from an immunoregulatory into an immune-activated phenotype and will also decrease MDSC burden in the microenvironment. 2.8.4 Optional Vaccine Site Biopsy DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 11 In patients who develop a vaccine site reaction, an optional biopsy of the vaccine site may be performed. Biopsy of the vaccine injection site will undergo immunohistochemical staining to assess for infiltrating lymphocytes which will be further characterized by mechanical disruption and flow cytometry to quantify recruitment of myeloma and antigen specific T cells. Presence of effector (CD62L/CD27) and central memory cells (CD62L/CD27) within the myeloma-specific and pentamer+ T cell populations will be determined by multichannel flow cytometry. 2.8.5 Optional Aspirate and Peripheral Blood Samples for future research In patients who consent to optional bone marrow aspirate and peripheral blood samples, we will cryopreserve these samples in the Avigan laboratory for future possible use in biomarker discovery and correlative studies including genomic analysis, whole exome sequencing, RNA sequencing, neoantigen discovery, proteomics, microRNA profiling, as well as additional immunologic assays. 3. PARTICIPANT SELECTION 3.1 Eligibility Criteria 3.1.1 Participant must have multiple myeloma and have relapsed following or are refractory to proteasome inhibitors, IMiDs and anti-CD38 mAb therapy 3.1.2 Participant must have at least 3 prior lines of therapy 3.1.3 Age ≥18 years. 3.1.4 ECOG performance status ≤2 3.1.5 Participant must have > 20% plasma cells in the bone marrow core or aspirate differential <30 days prior to enrollment. 3.1.6 ANC > 1K/uL; Platelets > 50 K/uL without transfusional support 3.1.7 Participant must have normal organ function as defined below:  total bilirubin ≤1.5 × institutional upper limit of normal  AST(SGOT) ≤3 × institutional upper limit of normal  ALT(SGPT) ≤3 × institutional upper limit of normal  creatinine clearance ≥40 mL/min for participants with creatinine levels above institutional normal. 3.1.8 The effects of DC/MM fusion and nivolumab on the developing human fetus are unknown. For this reason, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately. Men treated or enrolled on this protocol must also agree to use adequate contraception prior to the study, for the duration of study participation, and 5 months after completion of treatment. 3.1.9 Ability to understand and the willingness to sign a written informed consent document. 3.2 Exclusion Criteria DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 12 3.2.1 Participants who are receiving any other investigational agents. 3.2.2 Participants with purely non-secretory MM [absence of a monoclonal protein (M protein) in serum as measured by electrophoresis and immunofixation and the absence of Bence-Jones protein in the urine defined by use of conventional electrophoresis and immunofixation techniques and the absence of involved serum free light chain >100 mg/L]. Patients with light chain MM detected in the serum by free light chain assay are eligible. 3.2.3 Participants with Plasma Cell Leukemia 3.2.4 Because of compromised cellular immunity, patients who have a known human immunodeficiency virus (HIV), active hepatitis C virus (HCV) or active hepatitis B virus (HBV). 3.2.5 Myocardial infarction within 6 months prior to enrollment or New York Heart Association (NYHA) Class III or IV heart failure (see Appendix H), uncontrolled angina, severe uncontrolled ventricular arrhythmias, or electrocardiographic evidence of acute ischemia or active conduction system abnormalities. Prior to study entry, any ECG abnormality at screening will be documented by the investigator as not medically relevant. 3.2.6 Active or prior documented autoimmune or inflammatory disorders including but not limited to the following:  GI Disorders: (including inflammatory bowel disease [e.g. ulcerative colitis, Crohn’s disease], diverticulitis (with the exception of a prior episode that has resolved), celiac disease, or other serious gastrointestinal chronic conditions associated with diarrhea.  Systemic lupus erythematosus  Wegener’s syndrome [granulomatosis with polyangiitis]  Myasthenia gravis  Graves’ disease  Rheumatoid arthritis  Hypophysitis  Uveitis The following are exceptions to this criterion: subjects with vitiligo or alopecia; subjects with hypothyroidism (e.g. following Hashimoto syndrome) stable on hormone replacement; or subjects with psoriasis not requiring systemic treatment. 3.2.7 Individuals with a history of a different malignancy are ineligible except for the following circumstances. Note: Individuals with a history of other malignancies are eligible if they have been disease-free for at least 5 years and are deemed by the investigator to be at low risk for recurrence of that malignancy. Individuals with the following cancers are eligible if diagnosed and treated within the past 5 years: non-invasive cancer (such as, any in situ cancers) and basal cell or squamous cell carcinoma of the skin. 3.2.8 Female patients who are pregnant (positive β-HCG) or breastfeeding 3.2.9 Prior organ transplant requiring immunosuppressive therapy. 3.2.10 Patients who previously received PD-1 antibody and have experienced toxicities resulting in treatment discontinuation. 3.2.11 Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements. DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 13 3.3 Eligibility Prior to Vaccination with DC/MM fusions and nivolumab 3.3.1 Resolution of all chemotherapy related grade 3-4 toxicity as per CTC criteria 4.0 3.3.2 Successful production of at least 2 vaccines of a minimum of 1 x106 fusion cells 3.3.3 Absence of disease progression to standard of care therapy during the period of vaccine generation. 3.3.4 ECOG performance status ≤2 3.3.5 Participants must have normal organ function as defined below:  total bilirubin ≤1.5 × institutional upper limit of normal  AST(SGOT). ≤3 × institutional upper limit of normal  ALT(SGPT) ≤3 × institutional upper limit of normal  creatinine clearance ≥40 mL/min for participants with creatinine levels above institutional normal. 3.3.6 No myeloma therapy within 7 days of initiation of study treatment with the exception of steroids 3.4 Inclusion of Women and Minorities Both men and women of all races and ethnic groups are eligible for this trial. 4. REGISTRATION PROCEDURES 4.1 General Guidelines for DF/HCC Institutions Institutions will register eligible participants in the Clinical Trials Management System (CTMS) OnCore. Registrations must occur prior to the initiation of any protocol-specific therapy or intervention. Any participant not registered to the protocol before protocol-specific therapy or intervention begins will be considered ineligible and registration will be denied. An investigator will confirm eligibility criteria and a member of the study team will complete the protocol-specific eligibility checklist. Following registration, participants may begin protocol-specific therapy and/or intervention. Issues that would cause treatment delays should be discussed with the Overall Principal Investigator (PI). If the subject does not receive protocol therapy following registration, the subject must be taken off-study in the CTMS (OnCore) with an appropriate date and reason entered. 4.2 Registration Process for DF/HCC Institutions Applicable DF/HCC policy (REGIST-101) must be followed. 5. TREATMENT PLAN On this study, patients will be enrolled and undergo tumor collection and dendritic cell collection per protocol. Patients will undergo 1-2 cycles of standard of care therapy during the period of vaccine preparation. Patients for whom vaccine production is successful will undergo vaccination with DC/MM fusions on day 1 of cycle 1, 2, and 3. Subsequent cycles (following cycle 3) will consist of Nivolumab alone on Days 1 and 15 for a total of 6 cycles. 5.1 Evaluations Prior to Enrollment DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 14 The following evaluations must be performed within 2 weeks prior enrollment 1. History, physical examination, height and weight 2. ECOG Performance Status 3. Baseline AE Evaluation 4. CBC with differential 5. Liver Functions and blood chemistries: Na, K, Cl, CO2, Ca, Mg, PO4, Creatinine, total bilirubin, direct bilirubin, alkaline phosphatase, AST, ALT, LDH 6. Beta-2 Microglobulin, CRP 7. TSH, Free T4, Free T3 8. Evaluation of creatinine clearance 9. Pregnancy test in FOCBP 10. Laboratory Disease Evaluation:  Quantitative serum immunoglobulin levels.  Serum protein electrophoresis (SPEP).  24-hour urine collection to determine creatinine clearance and protein excretion, urine electrophoresis (UPEP).  Immunofixation of urine and serum protein regardless of SPEP and UPEP results.  Serum free light chain ratios (FLC) 11. Bone marrow to assess plasma cell involvement in the marrow as per eligibility criteria. Unilateral bone marrow biopsy and aspirate are required. If performed within 30 days it does not need to be repeated. 12. Skeletal bone survey to include cranium, axial skeleton and proximal long bones or alternative imaging to capture areas of bone disease 13. EKG 14. Vital signs (including ambulatory O2 sat) 5.2 Tumor Collection Following registration, patients will undergo collection of multiple myeloma cells through bone marrow aspirate collection. Bone marrow aspirates will be obtained (20-30cc) under local anesthesia. If there is an insufficient yield of tumor cells a second collection will be permitted. At the time of tumor collection, 50ml of plasma in sodium heparin tubes will be collected from the peripheral blood. This will be repeated if a second collection is indicated. Standard infectious serologies will be drawn as per BIDMC practice for storage of cellular products (drawn in 2 red top tubes and 3 pink top tubes and sent to the Stem Cell Lab at BIDMC). 5.3 Dendritic Cell Collection Patients may receive up to 1 cycle of bridging therapy prior to undergoing leukapheresis. Leukapheresis will be performed when after recovery of blood counts (an ANC >1000 K/uL and PLT >50 K/uL). When possible, leukapheresis will be performed via peripheral access. If peripheral access is inadequate, patients will undergo placement of a temporary central venous catheter. Standard infectious serologies will be drawn within 8 days of isolation dendritic cells as per BIDMC practice for storage of cellular products (drawn in 2 red top tubes and 3 pink top tubes and sent to the Stem Cell Lab at BIDMC). 5.4 SOC Anti-Myeloma Bridging Therapy During Period of Vaccine Preparation Patients may receive up to 2 cycles of standard of care therapy following leukapheresis. Bridging therapy is at the discretion of the physician, however the use of IMiDs (ie. Lenalidomide or pomalidomide) is prohibited. 5.5 Evaluation Prior to Initiation of Immunotherapy Patients will be evaluated within 14 days prior to initiation of immunotherapy. The following tests will be performed DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 15 at that time: 1. History, physical examination, height and weight 2. ECOG Performance Status 3. AE Assessment 4. Medications 5. CBC with differential, platelet count 6. Liver Functions and blood chemistries: Na, K, Cl, CO2, Ca, Mg, PO4, Creatinine, total bilirubin, direct bilirubin, alkaline phosphatase, AST, ALT, LDH 7. Beta-2 Microglobulin, CRP 8. TSH, Free T4, Free T3 9. Evaluation of creatinine clearance 10. Pregnancy test in females of child bearing potential 11. Laboratory Disease Evaluation:  Quantitative serum immunoglobulin levels.  Serum protein electrophoresis (SPEP).  24-hour urine collection to determine creatinine clearance and protein excretion, urine electrophoresis (UPEP).  Immunofixation of urine and serum protein regardless of SPEP and UPEP results.  Serum free light chain ratios (FLC) 12. Bone marrow biopsy and aspirate for re-staging, Note, if marrow was done within prior 6 weeks then this does not need to be repeated. 13. EKG 14. Skeletal bone survey or alternative imaging to include cranium, axial skeleton and proximal long bones or alternative imaging to capture areas of bone disease, if clinically indicated 15. Evaluation of Pre-Treatment Eligibility Criteria and registration to second time point on study. 5.6 Day 1 of Cycles 1-3 (+/- 3 days) 1. History, physical examination, height and weight 2. ECOG Performance Status 3. AE Assessment 4. Medications 5. CBC with differential, platelet count 6. Liver Functions and blood chemistries: Na, K, Cl, CO2, Ca, Mg, PO4, Creatinine, total bilirubin, direct bilirubin, alkaline phosphatase, AST, ALT, LDH 7. Beta-2 Microglobulin, CRP 8. TSH, Free T4, Free T3 9. Evaluation of creatinine clearance 10. Pregnancy test in FOCBP 11. Laboratory Disease Evaluation:  Quantitative serum immunoglobulin levels.  Serum protein electrophoresis (SPEP).  24-hour urine collection to determine creatinine clearance and protein excretion, urine electrophoresis (UPEP).  Immunofixation of urine and serum protein regardless of SPEP and UPEP results.  Serum free light chain ratios (FLC) 12. EKG 13. Nivolumab infusion (Per Section 5.12.1) 14. Vaccine administration (Per Section 5.12.2) 15. Vital Signs (including ambulatory O2 sat) per Section 11 16. Study tubes as per Section 10 will be drawn at the pre-immunotherapy visit. They will not be repeated at the start of C1, but will be drawn on day 1 of C2 and C3. DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 16 5.7 Day 15 of Cycles 1-3 (+/- 3 days) 1. History, physical examination, height and weight 2. ECOG Performance Status 3. AE Assessment 4. Medications 5. CBC with differential, platelet count 6. Liver Functions and blood chemistries: Na, K, Cl, CO2, Ca, Mg, PO4, Creatinine, total bilirubin, direct bilirubin, alkaline phosphatase, AST, ALT, LDH 7. EKG 8.