Patient-specific Vaccines Research Articles

Development of a Versatile Cancer Vaccine Format Targeting Antigen-Presenting Cells Using Proximity-Based Sortase A-Mediated Ligation of T-Cell Epitopes.

Cancer vaccines are a promising strategy to increase tumor-specific immune responses in patients who do not adequately respond to checkpoint inhibitors. Cancer vaccines that contain patient-specific tumor antigens are most effective but also necessitate the production of patient-specific vaccines. This study aims to develop a versatile cancer vaccine format in which patient-specific tumor antigens can be site-specifically conjugated by a proximity-based Sortase A (SrtA)-mediated ligation (PBSL) approach to antibodies that specifically bind to antigen-presenting cells to stimulate immune responses. DEC205 and CD169 are both receptors expressed on antigen-presenting cells that can be targeted to deliver antigens and stimulate T-cell responses. We used the CRISPR/HDR platform to produce mouse heavy chain IgG2a antibodies with DEC205 or CD169 specificity containing an SrtA recognition motif followed by a SpyTag at the C-terminus. Using a recombinant protein of SrtA linked to SpyCatcher, we applied proximity-based SrtA-mediated ligation to ligate fluorescein isothiocyanate (FITC)-labeled or antigenic peptides to the antibodies. Ligated antibodies bound to DEC205-expressing dendritic cells or CD169-expressing macrophages both in vitro and in vivo. More importantly, immunization with DEC205- or CD169-specific Abs linked to T-cell epitopes efficiently stimulated T-cell responses in vivo. To conclude, we have developed a cancer vaccine format using PBSL that enables the rapid incorporation of tumor antigens and could potentially be implemented for the synthesis of personalized cancer vaccines.

Use of a novel proteomimetic nanoplatform for simultaneous delivery of antigens with adjuvants to impact tumor growth in multiple tumor models.

40 Background: Patient-specific cancer vaccines derived from tumor antigen have been explored as a promising therapeutic strategy, however, challenges delivering vaccine components in a coordinated fashion to elicit antitumor responses remain. To overcome these, we utilize a novel nanoplatform called the Protein-Like Polymer (PLP), which allows for sustained and targeted delivery of tumor antigens in conjunction with adjuvants. Methods: PLPs containing peptide antigens were synthesized via ROMP and characterized. A library of compounds with different sidechain linkage chemistries, degrees of polymerization (DP), and inclusion/exclusion of Oligo-ethylene glycol (OEG) were made to determine design rules for immune activation. Cell uptake and functional assays using payload-specific T Cells were conducted. Immunization in three independent tumor models was done to show generalizability. Ability of PLPs to co-deliver adjuvants was tested by electrostatically coupling small molecule STING agonist, 2’3’ cGAMP. Results: Conjugating antigens to the polymer via a cleavable disulfide linkage, which reduces intracellularly in APCs, resulted in increased endosomal localization, higher levels of induced T cell proliferation, cytokine production, and expression of activation markers in CTLs and APCs. Incorporating a diluent amount of OEG side chains reduced enzymatic degradation while increasing immunogenicity and uptake. Additionally, increasing the DP, and therefore the density of antigen side chains, further improved vaccine efficacy and resistance to proteolysis. Antigen-PLP conjugates enhanced dendritic cell activation and T-cell response only when paired with cells from their cognate system, with no activity in immune cells not expressing receptors for the payload demonstrating antigen-specificity. Mice bearing established B16F10, MC38, or TC-1 tumors treated with PLPs containing gp100, adpgk, or E7 respectively all showed increased survival times, reduced tumor burden with corresponding changes in immune cell profiles, and immunological memory upon rechallenge. Impressively, mice treated with STING-PLP complexes had significantly smaller tumors vs control at day 14 (0.038g vs 0.76g; p < 0.0001) and allowed for subcutaneous administration of 2’3’ cGAMP, which traditionally requires intratumoral injection. Studies on the effects of vaccinating with pools of neoantigens multiplexed onto one PLP are ongoing. Conclusions: This work validates the ability of PLPs to overcome major limitations in cancer vaccine development. The modularity of the platform allows for complex nano-architectures including systems capable of delivering challenging compounds, ie small molecule STING agonists, subcutaneously through electrostatic coupling, highlighting its potential to revolutionize cancer vaccinology.

Abstract 481: Proteomimetic polymers limit tumor growth in multiple models via potent antigen-specific T cell activation

Abstract Background: Patient-specific cancer vaccines derived from tumor antigen have been explored as a promising therapeutic strategy, however, challenges delivering vaccine components in a coordinated fashion to elicit antitumor responses remain. To overcome these, we utilize a novel nanoplatform called the Protein-Like Polymer (PLP), which allows for sustained and targeted delivery of tumor antigens in conjunction with adjuvants. Methods: PLPs containing peptide antigens were synthesized via ring-opening metathesis polymerization (ROMP) and characterized. A library of compounds with different sidechain linkage chemistries, degrees of polymerization (DP), and inclusion/exclusion of Oligo-ethylene glycol (OEG) were made to determine design rules for immune activation. Cell uptake and functional assays using payload-specific T Cells were conducted. Immunization in three independent tumor models was done to show generalizability. Ability of PLPs to co-deliver adjuvants was tested by electrostatically coupling small molecule STING agonist, 2’3’ cGAMP. Results: Conjugating peptide antigens to the polymer via a cleavable disulfide linkage, which reduces intracellularly in APCs, resulted in increased endosomal localization, higher levels of induced T cell proliferation, cytokine production, and expression of activation markers in CTLs and APCs. Incorporating a diluent amount of OEG side chains reduced enzymatic degradation while increasing immunogenicity and uptake. Additionally, increasing the DP, and therefore the density of antigen side chains, further improved vaccine efficacy and resistance to proteolysis. Antigen-PLP conjugates enhanced dendritic cell activation and T-cell response only when paired with cells from their cognate system, with no activity in immune cells not expressing receptors for the payload demonstrating antigen-specificity. Mice bearing established B16F10, MC38, or TC-1 tumors treated with PLPs containing gp100, adpgk, or E7 respectively all showed increased survival times, reduced tumor burden with corresponding changes in immune cell profiles, and immunological memory upon rechallenge. Impressively, mice treated with STING-PLP complexes had significantly smaller tumors vs control at day 14 (0.038g vs 0.76g; p <0.0001) and allowed for subcutaneous administration of 2’3’ cGAMP, which traditionally requires intratumoral injection. Studies on the effects of vaccinating with pools of neoantigens multiplexed onto one PLP are ongoing. Conclusion: This work validates the ability of PLPs to overcome major limitations in cancer vaccine development. The modularity of the platform allows for complex nano-architectures including systems capable of delivering challenging compounds, ie small molecule STING agonists, subcutaneously through electrostatic coupling, highlighting its potential to revolutionize cancer vaccinology. Citation Format: Max Wang, Miran Choi, Bin Zhang, Nathan Gianneschi. Proteomimetic polymers limit tumor growth in multiple models via potent antigen-specific T cell activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 481.

Abstract 6519: Dendritic cell vaccine cell numbers and survival in patients with primary glioblastoma

Abstract Standard glioblastoma (GBM) treatment is associated with poor survival. A promising novel immunotherapy consists of autologous dendritic cells (DC) pulsed with autologous tumor antigens (ATA) from a lysate of irradiated self-renewing autologous cancer cells. An open-label, phase 2 trial was conducted in 57 patients with primary GBM. Here we report correlations between survival and DC-ATA doses. Two autologous intermediate products were manufactured for each patient: a tumor cell line established from resected GBM, and DC differentiated from cryopreserved peripheral blood monocytes (MC). Patients were enrolled prior to standard radiation therapy (RT) and temozolomide (TMZ) chemotherapy. DC-ATA were manufactured during RT/TMZ, divided into individual doses, then cryopreserved in liquid nitrogen. For each patient-specific vaccine batch, cell numbers were calculated using a hemocytometer; viability was determined before cryopreservation (cryo) using trypan blue and post-cryo using 7ADD per flow cytometry. After RT/TMZ, up to 8 doses were injected s.c. concurrent with TMZ over 6 months. Patients were grouped into tertiles based on DC-ATA cell numbers and survival. Prism 10.03 was used to generate survival curves and calculate correlation coefficients and log-rank and T-Test comparisons. As previously reported, cell line success rate was 71/73, sufficient MC numbers were collected by leukapheresis for 63/65; DC-ATA was successfully manufactured for 60/60; 57 patients were treated; median progression free survival (PFS) and overall survival (OS) were 10.4 and 16.0 months respectively. Correlations were strong between total and viable DC-ATA pre-cryo (0.97, p<0.0001) and post-cryo (0.95, p<0.0001), but weaker between DC-ATA pre- and post-cryo (0.30, p=0.02), and between viable DC-ATA pre- and post-cryo (0.37, p=0.004). When patients were grouped by OS tertiles, medians were 9.8, 18.1, and more than 36 months. There were no differences in the average millions (M) of DC-ATA pre-cryo (10.0, 9.7, 9.6), viable DC-ATA pre-cryo (8.5, 7.8, 7.9), DC-ATA post-cryo (9.0, 10.3, 10.8) or viable DC-ATA post-cryo (6.0, 7.3, 7.4). Similarly, when patients were grouped into tertiles by DC-ATA numbers, there were no differences in OS curves associated with DC-ATA pre-cryo, viable DC-ATA pre-cryo, DC-ATA post-cryo, or viable DC-ATA post-cryo. Pre-cryo viable DC-ATA numbers ranged from 0.27 to 27.0 M. An ineffective dose was not identified; pre-cryo viable DC-ATA doses of less than 2M were associated with OS of 10.4, 13.0, 13.3, and 36.4+ months. Also, there was no OS difference by number of MC used to manufacture DC or by number of DC manufactured. In conclusion, there was no evidence for a dose/response relationship between DC-ATA dose and OS for any of the parameters tested. This data supports that pre-cryo cell counts can be used to establish treatment doses. Pre-cryo viable cell counts of 2M DC-ATA per dose seem sufficient. Citation Format: Robert O. Dillman, Gabriel I. Nistor, Krystal Godding, Rockelle Robles, Hans S. Keirstead. Dendritic cell vaccine cell numbers and survival in patients with primary glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6519.

Health Care Provider Knowledge and Attitudes Regarding Adult Pneumococcal Conjugate Vaccine Recommendations - United States, September 28-October 10, 2022.

Despite the availability of effective vaccines against pneumococcal disease, pneumococcus is a common bacterial cause of pneumonia, causing approximately 100,000 hospitalizations among U.S. adults per year. In addition, approximately 30,000 invasive pneumococcal disease (IPD) cases and 3,000 IPD deaths occur among U.S. adults each year. Previous health care provider surveys identified gaps in provider knowledge about and understanding of the adult pneumococcal vaccine recommendations, and pneumococcal vaccine coverage remains suboptimal. To assess the feasibility and acceptability domains of the Advisory Committee on Immunization Practices (ACIP) Evidence to Recommendations (EtR) framework, a health care provider knowledge and attitudes survey was conducted during September 28-October 10, 2022, by the Healthcare and Public Perceptions of Immunizations Survey Collaborative before the October 2022 ACIP meeting. Among 751 provider respondents, two thirds agreed or strongly agreed with the policy option under consideration to expand the recommendations for the new 20-valent pneumococcal conjugate vaccine (PCV20) to adults who had only received the previously recommended 13-valent pneumococcal conjugate vaccine (PCV13). Gaps in providers' knowledge and perceived challenges to implementing recommendations were identified and were included in ACIP's EtR framework discussions in late October 2022 when ACIP updated the recommendations for PCV20 use in adults. Currently, use of PCV20 is recommended for certain adults who have previously received PCV13, in addition to those who have never received a pneumococcal conjugate vaccine. The survey findings indicate a need to increase provider awareness and implementation of pneumococcal vaccination recommendations and to provide tools to assist with patient-specific vaccination guidance. Resources available to address the challenges to implementing pneumococcal vaccination recommendations include the PneumoRecs VaxAdvisor mobile app and other CDC-developed tools, including summary documents and overviews of vaccination schedules and CDC's strategic framework to increase confidence in vaccines and reduce vaccine-preventable diseases, Vaccinate with Confidence.

Treatment-related adverse events in a randomized trial in stage three and four ovarian cancer testing patient-specific dendritic cell vaccines loaded with tumor antigens from self-renewing autologous tumor cells (1258)

Treatment-related adverse events in a randomized trial in stage three and four ovarian cancer testing patient-specific dendritic cell vaccines loaded with tumor antigens from self-renewing autologous tumor cells (1258)

Use of proteomimetic polymers for delivery of tumor antigens and adjuvants through formation of stable electrostatic complexes with small molecule STING agonists.

2583 Background: Utilizing tumor antigens for the development of patient-specific cancer vaccines has been a promising therapeutic strategy. However, significant challenges remain in delivering subunit vaccine components to elicit antitumor immune responses. To overcome these, we developed rationally designed cancer vaccines using a new nanoplatform called the Protein-Like Polymer (PLP) with unique characteristics that allow for sustained delivery of tumor antigens in conjunction with immunomodulatory compounds. Methods: PLPs containing antigens were synthesized via ring-opening metathesis polymerization (ROMP) and characterized using HPLC, LC-MS, NMR, and GPC. A library of compounds were generated with different sidechain linkage chemistries (amide, ester, or disulfide linkage), DPs, and inclusion of PEG side chains. In vitro assays using gp100-specific T Cells were conducted with fluorescently labeled and non-labeled polymers. In vivo experiments were done using B16 murine melanoma transplanted tumor models. Ability of PLPs to co-deliver immunomodulatory compounds was tested using a small molecule STING agonist 2’3’ cGAMP. Results: Conjugating antigens to the polymer backbone using a cleavable disulfide linkage, designed to be reduced intracellularly, resulted in the best subcellular localization and immune activation (higher levels of immune cell proliferation, cytokine production, and expression of activation markers). Incorporating a diluent amount of PEG side chains increased resistance to enzymatic degradation while improving bioactivity and cell uptake. In vivo studies using PLPs conjugated with melanoma-associated antigen gp100 showed the reductions in tumor size with increased immune cell proliferation and activation in a B16 melanoma model. Additionally, increasing the degree of polymerization, and therefore the density of antigen side chains per unit polymer, improved vaccine efficacy and resistance to proteolysis. Mice treated with STING agonists electrostatically coupled to PLPs showed significantly smaller tumors vs no-treatment at day 14 (0.038g vs 0.76g; p <0.0001) and allowed for subcutaneous administration of the small molecule, which normally must be injected intratumorally. Conclusions: Our work demonstrates the potential of PLPs to overcome inherent difficulties associated with developing cancer vaccines. The modularity of the platform allows for complex nano-architectures including systems capable of delivering challenging compounds, ie small molecule STING agonists, subcutaneously through electrostatic coupling. This technology has the potential to revolutionize cancer vaccinology.

Abstract CT571: Plasma proteomic markers prognostic or predictive for survival of patients with newly diagnosed glioblastoma who were treated in a phase II trial with standard care and the addition of the novel patient-specific dendritic cell vaccine AV-GBM-1

Abstract Standard aggressive therapy for primary newly diagnosed glioblastoma (GBM), which includes surgical resection followed by concurrent radiation therapy and temozolomide chemotherapy (RT/TMZ) and then maintenance TMZ, is associated with poor survival rates. Adding treatment with AV-GBM-1, a personal vaccine consisting of autologous dendritic cells (DC) pulsed with autologous tumor antigens (ATA) may improve survival. AV-GBM-1 is produced by incubating ATA with autologous DC. ATA are from a lysate of irradiated autologous GBM cells that were self-renewing in serum-free medium with factors that favor survival and proliferation of tumor initiating cells, i.e., stem cells and early progenitor cells. After recovery from RT/TMZ, GBM patients were injected subcutaneously with AV-GBM-1 admixed in granulocyte-macrophage colony-stimulating factor (GM-CSF) at weeks 1, 2, 3, 8, 12, 16, 20, and 24. This study examined changes in plasma proteomics before and after injections of AV-GBM-1. 57 patients were treated during November 2018 to October 2020. Median progression-free and overall survival were 10.3 and 16.0 months respectively. Plasma samples obtained at baseline (week-0), and just prior to the third injection (week-2) were cryopreserved and subsequently analyzed for 448 proteomic markers using quantitative, multiplex enzyme-linked immunosorbent assays (Raybiotech, Inc., Norcross, GA.). 54 patients had a baseline week-0 sample prior to the 1st vaccination; 50 had a week-2 sample just prior to the 3rd dose; 49 had paired samples for both time-points. The averages of paired samples were measured for all patients and for cohorts defined by median survival that were compared by 2-tail T-Tests. After two weekly injections there were significant (p<0.01) increases in thymus and activation-regulated chemokine (TARC, CCL17), chemerin, lipocalin-2 and angiopoietin, and decreases in thrombospondin-5, angiotensinogen, and beta-fibroblast growth factor. The changes in TARC are due to GM-CSF. 25 patients survived more than 15 months and 24 less than 15 months. Prognostic baseline markers associated with longer survival were higher CD14 (p=0.009), higher tissue-inhibitor of metalloproteinases (TIMP-1), and higher insulin growth factor binding proteins (IGFBP) 1 and 2 (p<0.02). The only markers that appeared predictive for survival (p<0.05) based on changes from baseline to week-2 were increased lipocalin-2, associated with longer survival (p=0.0369), and decreased brain-derived neurotrophic factor (BDNF) associated with shorter survival (p=0.0186). Because of the large number of analyses, these results are considered hypothesis generating and not definitive. Citation Format: Daniela A. Bota, David E. Piccioni, Christopher M. Duma, Renato V. LaRoca, Santosh Kesari, Mehrdad Abedi, Robert D. Aiken, Aleksandra J. Poole, Gabriel I. Nistor, Robert O. Dillman. Plasma proteomic markers prognostic or predictive for survival of patients with newly diagnosed glioblastoma who were treated in a phase II trial with standard care and the addition of the novel patient-specific dendritic cell vaccine AV-GBM-1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT571.

Seizures as treatment-emergent adverse events during glioblastoma clinical trials.

e14018 Background: Seizures are not an uncommon presenting symptom of glioblastoma (GBM), and may occur following surgery for GBM. Such seizures typically can be controlled with anti-epileptics, and the risk of seizures seems to decrease after concurrent radiation therapy and temozolomide chemotherapy (RT/TMZ). However, the risk of seizures theoretically might be increased in association with a therapeutic intervention designed to enhance local inflammation at the GBM site. 33% of patients experienced one or more seizures as a treatment-emergent-adverse-event (TEAE) during a phase II clinical trial of AV-GBM-1, patient-specific dendritic cell vaccines that consist of autologous dendritic cells loaded with autologous tumor associated antigens derived from a short-term culture of self-renewing tumor cells, that were injected subcutaneously for up to six months after recovery following concurrent RT/TMZ (Bota DA et al. 2021 Society for Immunotherapy of Cancer (SITC) late-breaking abstract #952, 2021 Society of Neuro-Oncology abstract #CTIM-33). A literature search was conducted to determine reported rates of seizures as TEAE in primary GBM patients in clinical trials. Methods: Phase III trials of systemic treatment of primary GBM, and published during 2005 to 2021, were identified by searches of clinicaltrials.gov and PubMed. Published reports were reviewed for data describing the frequency of seizures reported as TEAE in text and/or summary tables. Only trials that had at least 50 patients in a standard treatment arm of surgical resection, RT/TMZ and maintenance TMZ were included. Chi square test was used to compare proportions of patients experiencing seizures in these trials. Results: Eight such randomized trials were identified. Five trials did not mention seizures as TEAE. One trial provided data only for grade 3 and 4 events: 13/229 (5.7%). The other two trials reported all seizures regardless of grade, but were limited to patient populations with O6-methylguanine-DNA-methyltransferase promoter methylation in one, and epidermal growth factor receptor amplification in the other. The rates of seizures in those two trials were much lower than the 19/57 (33.0%) reported with AV-GBM-1: 28/258 (10.9%, p < 0.0001), and 69/372 (15.4%, p = 0.0136). Conclusions: The frequency of seizures that occur in GBM patients receiving standard RT/TMZ is not well-documented in publications of large, randomized trials. AV-GBM-1 may be associated with a higher rate of seizures because of treatment-induced inflammation at the tumor site, but a randomized trial would be needed to determine this.

A novel polymeric peptide delivery platform and association with targeted co-delivery of antigens and STING agonists with antitumor immune response.

2564 Background: Use of tumor antigens for the development of patient-specific cancer vaccines has been a promising therapeutic strategy. However, challenges remain in delivering subunit vaccine components in a coordinated fashion to elicit antitumor immune responses. To overcome these, we developed rationally designed vaccines using a novel nanoplatform called the Protein-Like Polymer (PLP), in reference to its globular structure reminiscent of native proteins, with unique characteristics that allow for sustained/targeted delivery of tumor antigens in conjunction with STING agonists. Methods: PLPs containing a model melanoma antigen were synthesized via ring-opening metathesis polymerization (ROMP) and characterized. A library of compounds were generated with different sidechain linkage chemistries (amide, ester, or disulfide), degrees of polymerization, and inclusion/exclusion of Oligo(ethylene glycol) (OEG) side chains. In vitro uptake and functional assays using gp100-specific T Cells were conducted with fluorescently-labeled and non-labeled polymers respectively. In vivo experiments were done using a B16F10 murine melanoma tumor model over-expressing gp100. Ability of PLPs to co-deliver immunomodulatory compounds was tested by electrostatically coupling a small molecule STING agonist 2’3’ cGAMP which formed stable nanostructures. The optimized construct was also tested in an OVA system to prove generalizability. Results: Conjugating peptide antigens using a cleavable disulfide linkage, which reduces intracellularly in antigen presenting cells (APCs), resulted in increased endosomal localization and efficacy. Incorporating a diluent amount of OEG side chains increased resistance to enzymatic degradation while improving bioactivity and uptake by APCs. In vivo studies using PLPs conjugated with gp100 resulted in significant increases in survival time and reduced tumor burden in B16 melanoma. Increasing the DP, and therefore the density of antigen side chains, improved vaccine efficacy and resistance to proteolysis. Mice treated with STING-PLP complexes showed significantly smaller tumors vs control at day 14 (0.038g vs 0.76g; p < 0.0001) and allowed for subcutaneous administration of 2’3’ cGAMP, which otherwise diffuses rapidly away from the injection site. OVA-PLPs behaved similarly in their cognate system but showed no activity when tested on gp100-specific cells and vice versa demonstrating antigen-specificity. Conclusions: This work validates the potential of PLPs to overcome major limitations in cancer vaccine development. The modularity of the platform allows for complex nano-architectures including systems capable of delivering challenging compounds, ie small molecule STING agonists, subcutaneously through electrostatic coupling. This technology has the potential to revolutionize cancer vaccinology.

A phase I study to evaluate the safety and effectiveness of neoantigen-based personalized dendritic cell vaccine in patients with advanced solid tumors.

e14512 Background: Patients with solid tumor may get benefits from neoantigen-based cancer vaccines, which has showed some clinical efficacy data in clinical trials. This study was designed to evaluate the safety and efficacy of a neoantigen-based dendritic cell vaccine in patients with advanced solid tumors Methods: In this single arm study, patient-specific mutation-containing epitopes were detected from patient's tumor tissue. Tumor specimens were processed for whole transcriptome RNA sequencing, whole exome sequencing and HLA typing analysis. Total 10-20 immunogenic neoantigens for each patient were formulated and loaded into patient’s dendritic cells to manufacture the patient-specific anti-cancer vaccines. The patient was administered vaccine injections (Days 0, 14, 35, 56 and 98) into inguinal lymph nodes and intra-cutaneous. Peripheral blood was collected during the treatment (Days 14,15, 35, 36, 56, 57,77, 99 and 120) for safety evaluation and for assessment of the expansion of antigen-specific T cells in vivo. Patients were followed up until confirmed disease progression, withdrawal consent or adverse event intolerance. Results: Between 2019 and 2020, six patients received the neoantigen-based DC vaccine. The tumor types were laryngeal carcinoma, leiomyosarcoma, biliary tract carcinoma and hepatocellular carcinoma. All six enrolled patients had stage III or IV disease and had failed at least one line of systematic therapy at baseline. Preliminary data revealed that 6 pts (5 female and 1 male) with mean age of 44 (41-50) yrs. received ≥3 dose of DC vaccine. Doses ranged from 2×106 cells/ml to 10×106 cells/ml. All observed treatment related Adverse Events were Grade 1 or Grade 2. The most common (≥10%) drug-related adverse events were fatigue (15%), fever (15%), and elevated AST (20%). Five patients received at least one disease assessment post baseline visit. There were no tumor response. The patient with biliary tract carcinoma, laryngeal ca, leiomyosarcoma had SD status for 11 weeks, 30 weeks and 16 weeks respectively. Patients were assessed with the ELISPOT, which showed a CD8 + neoantigen-specific T-cells expansion was detected from each of the six patients’ peripheral blood after the fifth vaccine injection, which demonstrate the preliminary proof of concept for this personalized neoantigen-based dendritic cell vaccine. Conclusions: In this study, neoantigen-based dendritic cell vaccine has showed preliminary activity in advanced solid tumor patients with well-tolerated safety profile, which indicated the neoantigen-targeting DC vaccine has potential to be an effective treatment (with alteration of the immune cell milieu) in solid tumor patients.

CTIM-26. PATIENT-SPECIFIC DENDRITIC CELL VACCINE (DC-ATA) PULSED WITH ANTIGENS FROM SELF-RENEWING AUTOLOGOUS TUMOR CELLS IN THE TREATMENT OF NEWLY-DIAGNOSED GLIOBLASTOMA: A PHASE II TRIAL

Abstract GBM standard treatment is associated with poor survival. Adjunctive therapy with patient-specific vaccines may improve outcomes by enhancing anti-GBM immune responses. A multi-institutional phase II clinical trial was designed with a primary objective of 75% survival 15 months after intent-to-treat enrollment. IL-4 and GM-CSF were used to generate dendritic cells (DC) from monocytes. DC were incubated with autologous tumor antigens (ATA) from the lysate of cultured GBM cells to produce each patient-specific DC-ATA vaccine. Each dose was admixed with 500 mcg GM-CSF at the time of subcutaneous injections at weeks 1, 2, 3, 8, 12, 16, 20 and 24. Enrollment has been completed in April 2020 (n=60). Three patients withdrew from the study prior to starting treatment leaving 57 patients for whom data is available. So far 57 patients have received 344 doses; 27 have completed all 8 doses, 11 received fewer than 8 doses at the time they discontinued treatment, 19 are currently in treatment. No patient has discontinued treatment because of toxicity. 9 pt had died and the preliminary 12 months overall survival is 74%. In a preliminary serologic analysis 12 of 16 patients (75%) had an increase in markers associated with Th1/NK, Th2/immunoglobulins, and Th2 hypersensitivity (eotaxins, IgE and IL17F) by week-3; 9 of 15 (60%) had a decrease in angiogenesis factors, growth factors, and tumor markers by week-8. Immunologic data for all 55 patients who received at least two injections will be available November 2020. This patient-specific DC-ATA immunotherapy approach is feasible, is associated with changes in serologic markers, and may be increasing intratumor inflammation that may be associated with on-target toxicity and efficacy. A interim survival analysis will be conducted in mid-October 2020, 15 months after the 28th patient was enrolled; results will be available November 2020 [Clinicaltrials.gov NCT03400917].

Abstract CT182: Adjunctive treatment of primary glioblastoma with patient-specific dendritic cell vaccines pulsed with antigens from self-renewing autologous tumor cells: A phase II trial

Abstract Standard treatment of primary glioblastoma (GBM) is associated with poor survival. Adjunctive therapy with patient-specific vaccines may improve outcomes by inducing or enhancing each patient's anti-GBM immune response. A multi-institutional phase II clinical trial was designed with a primary objective of 75% survival 15 months after intent-to-treat enrollment. Key eligibility criteria were: (1) primary GBM diagnosis, (2) age < 70 years at time of tumor resection, (3) successful cell culture of GBM cells in serum-free media, (4) successful monocyte collection by leukapheresis, and (5) KPS > 70 after recovery from surgery. IL-4 and GM-CSF were used to generate dendritic cells (DC) from monocytes. DC were incubated with autologous tumor antigens (ATA) from the lysate of cultured GBM cells to produce each patient-specific DC-ATA vaccine. Each dose was admixed with GM-CSF at the time of subcutaneous injections at weeks 1, 2, 3, 8, 12, 16, 20 and 24. At the time of this analysis, cell line success rate is 61/63 (97%); monocyte collection success rate is 53/55 (96%), but 10 patients required a second apheresis. 50 of a planned 55 patients have enrolled after recovery from surgery, just prior to starting standard concurrent radiation therapy (RT) and temozolomide (TMZ), with intent-to-treat after recovery from RT/TMZ. The 50 patients include 36 men and 14 women; median age is 58 years with a range of 27 to 70. Average KPS is 82.8. MGMT methylation has been documented in 22% of patients and IDH mutation in 14%. 37 patients have started treatment and received 231 doses. 16 have completed all 8 doses, 7 received fewer than 8 doses, and 14 are currently undergoing treatment. No patient has discontinued treatment because of toxicity, but 20 patients have experienced 35 treatment-emergent serious adverse events including hospitalizations for falls and/or increased focal weakness (12 episodes), seizures (10 episodes), or severe headaches or visual changes (3 episodes). 6-month actual survival rate is 96% for the 28 patients at risk 6 months or longer from enrollment. Serologic analyses show that 12 of 16 patients (75%) had an increase in markers associated with Th1/NK, Th2/immunoglobulins, and Th2 hypersensitivity (eotaxins, IgE and IL17F) by week-3; 9 of 15 (60%) had a decrease in angiogenesis factors, growth factors, and tumor markers by week-8. On serial MRI scans, 7 of 13 patients (54%) have exhibited an increase in T2 (tumor) and flare (edema) for several weeks after starting DC-ATA, followed by a slow gradual decrease in both. This patient-specific DC-ATA immunotherapy approach is feasible, is associated with changes in serologic markers, and may be increasing intratumor inflammation that may be associated with on-target toxicity and efficacy. Longer follow up is needed before the survival objective can be assessed. [Clinicaltrials.gov NCT03400917] Citation Format: Daniella A. Bota, Christopher M. Duma, Santosh Kesari, David E. Piccioni, Renato V. LaRocca, Robert T. O'Donnell, Robert D. Aiken, Jose A. Carrillo, Candace Hsieh, Chris J. Langford, Krystal Carta, Adrienne M. Wang, James A. Langford, Thomas H. Taylor, Gabriel I. Nistor, Robert O. Dillman. Adjunctive treatment of primary glioblastoma with patient-specific dendritic cell vaccines pulsed with antigens from self-renewing autologous tumor cells: A phase II trial [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT182.

Abstract CT189: Patient-specific dendritic cell vaccines with tumor antigens from self-renewing autologous tumor cells in the treatment of primary advanced ovarian cancer: A multi-institutional phase II clinical trial

Abstract Standard treatment of primary ovarian epithelial cancer has improved, but 5-year survival is only about 40% for the cohort of patients who present with stage 3 or 4 disease. Adjunctive therapy with patient-specific vaccines may improve outcomes by enhancing each patient's anti-cancer immune response. A multi-institutional, double- blinded randomized phase II clinical trial was designed with a primary objective of a 50% reduction in the risk of death compared to the control arm. Key eligibility criteria are: (1) primary diagnosis of stage 3 or 4 ovary epithelial cancer, (2) successful cell culture of ovarian cancer cells, (3) successful monocyte collection by leukapheresis, and (4) ECOG of 0 or 1 at the time of randomization. After completing primary systemic therapy, patients are stratified based on whether they have any residual evidence of disease and then randomized 2:1 to vaccine or control arms. Randomization occurs about 7 months after initial surgery. In the active arm IL-4 and GM-CSF are used to differentiate monocytes into dendritic cells (DC) which are incubated with the lysate of cultured ovary cancer cells as the source of autologous tumor antigens (ATA) to produce each patient-specific DC-ATA vaccine. Patients in the control arm receive cryopreserved autologous monocytes from their leukapheresis product. Each dose is admixed with 500 mcg GM-CSF at the time of subcutaneous injections at weeks 1, 2, 3, 8, 12, 16, 20 and 24. DC-ATA may be given alone or in combination with maintenance or salvage therapies. At the time of this analysis, cell line success rate is 35/35 (100%); monocyte collection success rate is 19/20 (95%), and 2 patients required a second apheresis to get a satisfactory product. 14 patients had primary ovarian, 2 fallopian tube, and 1 primary intraperitoneal cancer. 17 of a planned 99 have been randomized. At diagnosis 15 patients had stage 3 disease and two had stage 4; 15 had no evidence of disease at the time of randomization. Primary systemic therapy was adjuvant for 7 and neoadjuvant for 10. Ages of the randomized patients range from 39 to 80 years with a median of 61 years. ECOG status was 0 for 11 subjects, and 1 for 6 subjects. 13 patients have started treatment and received 92 injections; 9 have received all 8 doses and only 2 have stopped before 8 doses. No patient has discontinued treatment because of toxicity, but 1 patient was hospitalized after the 8th dose for refractory urticaria that resolved after high-dose corticosteroids followed by slow tapering. This patient-specific DC-ATA immunotherapy approach is feasible in patients with primary advanced ovarian cancer. The clinical trial is continuing as planned. [Clinicaltrials.gov NCT02033616] Citation Format: Lisa N. Abaid, Bradley R. Corr, James R. Mason, Richard L. Friedman, Ramez N. Eskander, Candace Hsieh, Chris J. Langford, Krystal Carta, Adrienne M. Wang, James A. Langford, Gabriel I. Nistor, Robert O. Dillman. Patient-specific dendritic cell vaccines with tumor antigens from self-renewing autologous tumor cells in the treatment of primary advanced ovarian cancer: A multi-institutional phase II clinical trial [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT189.

Abstract 4566: Performance of neoantigen prediction for the design of TG4050, a patient specific neoantigen cancer vaccine

Abstract The development of therapeutic cancer vaccines to immunize against tumor antigens constitutes a promising modality. Mutation associated antigens are considered major targets given their specificity to tumor cells. These mutations are specific to the patients and require a tailor-made vaccine targeting mutations identified in each tumor. Many mutations are identified in the tumoral genome in most patients, but only a small fraction (around 1%) is suitable as vaccine target. Herein, we report data documenting the prediction performance of the algorithm used for the design of TG4050, a clinical stage patient specific viral-based neoantigen vaccine. We have trained a set of independent machine learning algorithms to score each candidate neoantigen for several steps of the MHC antigen presentation pathway, including MHC binding, intracellular processing, similarity to self, and likelihood to elicit a T-cell response in peptide stimulated ELISPOT. Further, we have developed a novel graph neural network to combine all these scores to predict the likelihood that a neoantigen will elicit a T-cell response while also incorporating patient-specific factors, such as expression level and conservation of the mutation across different clones. To validate the system, we collected samples from 6 patients diagnosed with NSCLC, sequenced healthy and tumor tissue, identified mutations and ranked them using our algorithm; then, to evaluate immunogenicity, we focused our analysis on CD8+ T cell and measured the frequency of IFN γ+ cells against predicted peptides in autologous PBMC. Immunogenicity of peptides was assayed in 5 pools then deconvoluted against individual peptides. From 3339 to 4782 somatic variants were detected in tumor tissue samples. After applying technical filtering, removing synonymous mutations, and filtering on transcript expression we detected a median of 281 (192-471) expressed tumor mutations resulting in a median of 2767 candidate class I epitopes (1769 - 4573). The model resulted in high accuracy allowing us to identify peptides with pre-existing ex vivo immunogenic responses in 5 out of 6 patients. Immunogenicity of peptide pools was correlated with ranking by the algorithm. Immunogenicity of the 6 top ranking individual epitopes in each patient showed a median of 5 (2-6) immunogenic peptides resulting in a 77% of true positive rate (TP). It should be noted that when no response was detected, it cannot be excluded that a response could be primed by a vaccine. In a similar setting, the netMHC 4.0 algorithm yielded a TP of 30% and only identified 39% of positive calls of our algorithm. We demonstrate that the prediction algorithm is accurate in identifying immunogenic cancer mutations even among a large set of candidates. Ongoing TG4050 clinical studies (NCT03839524 and NCT04183166) will allow further validation of the antitumor activity of the elicited immune response. Citation Format: Brandon Malone, Caroline Tosch, Benoit Grellier, Kousuke Onoue, Timo Sztyler, Karola Rittner, Yoshiko Yamashita, Eric Quemeneur, Kaidre Bendjama. Performance of neoantigen prediction for the design of TG4050, a patient specific neoantigen cancer vaccine [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4566.

Cytokine network analysis of immune responses before and after autologous dendritic cell and tumor cell vaccine immunotherapies in a randomized trial

BackgroundIn a randomized phase II trial conducted in patients with metastatic melanoma, patient-specific autologous dendritic cell vaccines (DCV) were associated with longer survival than autologous tumor cell vaccines (TCV). Both vaccines presented antigens from cell-renewing autologous tumor cells. The current analysis was performed to better understand the immune responses induced by these vaccines, and their association with survival.Methods110 proteomic markers were measured at a week-0 baseline, 1 week before the first of 3 weekly vaccine injections, and at week-4, 1 week after the third injection. Data was presented as a deviation from normal controls. A two-component principal component (PC) statistical analysis and discriminant analysis were performed on this data set for all patients and for each treatment cohort.ResultsAt baseline PC-1 contained 64.4% of the variance and included the majority of cytokines associated with Th1 and Th2 responses, which positively correlated with beta-2-microglobulin (B2M), programmed death protein-1 (PD-1) and transforming growth factor beta (TGFβ1). Results were similar at baseline for both treatment cohorts. After three injections, DCV-treated patients showed correlative grouping among Th1/Th17 cytokines on PC-1, with an inverse correlation with B2M, FAS, and IL-18, and correlations among immunoglobulins in PC-2. TCV-treated patients showed a positive correlation on PC-1 among most of the cytokines and tumor markers B2M and FAS receptor. There were also correlative changes of IL12p40 with both Th1 and Th2 cytokines and TGFβ1. Discriminant analysis provided additional evidence that DCV was associated with innate, Th1/Th17, and Th2 responses while TCV was only associated with innate and Th2 responses.ConclusionsThese analyses confirm that DCV induced a different immune response than that induced by TCV, and these immune responses were associated with improved survival.Trial registration Clinical trials.gov NCT004936930 retrospectively registered 28 July 2009

Automated Flow Synthesis of Tumor Neoantigen Peptides for Personalized Immunotherapy

High-throughput genome sequencing and computation have enabled rapid identification of targets for personalized medicine, including cancer vaccines. Synthetic peptides are an established mode of cancer vaccine delivery, but generating the peptides for each patient in a rapid and affordable fashion remains difficult. High-throughput peptide synthesis technology is therefore urgently needed for patient-specific cancer vaccines to succeed in the clinic. Previously, we developed automated flow peptide synthesis technology that greatly accelerates the production of synthetic peptides. Herein, we show that this technology permits the synthesis of high-quality peptides for personalized medicine. Automated flow synthesis produces 30-mer peptides in less than 35 minutes and 15- to 16-mer peptides in less than 20 minutes. The purity of these peptides is comparable with or higher than the purity of peptides produced by other methods. This work illustrates how automated flow synthesis technology can enable customized peptide therapies by accelerating synthesis and increasing purity. We envision that implementing this technology in clinical settings will greatly increase capacity to generate clinical-grade peptides on demand, which is a key step in reaching the full potential of personalized vaccines for the treatment of cancer and other diseases.

Genomic, proteomic, and immunologic associations with a durable complete remission of measurable metastatic melanoma induced by a patient-specific dendritic cell vaccine

ABSTRACT This report describes efforts to understand the immune mechanism of action that led to a complete response in a patient with progressive, refractory, metastatic melanoma after treatment with a therapeutic vaccine consisting of autologous dendritic cells (DC) loaded with autologous tumor antigens (ATA) derived from cells that were self-renewing in cell culture. Her histocompatibility type proved to be HLA B27 with extensive mutations in the HLA-A locus. Exomic analysis of proliferating tumor cells revealed more than 2800 non-synonymous mutations compared to her leukocytes. Histology of resected tumor lesions showed no evidence of an existing or suppressed immune response. In in vitro mixed cell cultures, DC loaded with ATA induced increased IL-22 expression, and a four-fold increase in CD8 + T lymphocytes. Cryopreserved blood samples obtained at week-0, 1 week before the first of three-weekly vaccine injections, and at week-4, 1 week after the third dose, were analyzed by protein array and compared for 110 different serum markers. At baseline, she had marked elevations of amyloid A, IL-12p40, IL21, IL-22, IL-10, IL-16, GROa, TNF-alpha, IL-3, and IL-2, and a lesser elevation of IL-15. One week after 3 weekly vaccinations she had a further 80% increase in amyloid A, a further 66% increase in IL-22, a 92% decrease in IL12p40, a 45% decrease in TGF-β and 26% decrease in IL-10. The data suggested that by 3 weeks after the first DCV injection, vaccine-induced changes in this particular patient were most consistent with enhanced innate and Th1 immune responses rather than Th2 or Th17.

Maria-I: A Deep-Learning Approach for Accurate Prediction of MHC Class I Tumor Neoantigen Presentation

Background: Therapeutic cancer vaccines targeting neoantigens have shown promise in early phase clinical trials for inducing tumor-specific T-cell responses in diverse tumor types. Identification of the small number of optimal cancer vaccine targets is essential to limit cost and improve efficacy of patient-specific vaccine design. Therefore, there is a need to narrow neoantigen selection to those peptides with the highest potential to induce anti-tumor immune responses, and to maximize the associated clinical benefits. The presentation of these antigens by Major Histocompatibility Complex (MHC) class I is key for prioritizing candidates. Previous algorithms to predict antigen presentation have had limited success and have primarily been trained on in-vitro binding affinity assays, or are commercial platforms not widely available for use. Methods: We previously developed MARIA (MHC Analysis with Recurrent Integrated Architecture) as a method for predicting MHC-II neoantigens [Chen B et al. 2017 ASH, and Chen et al. 2019, Nature Biotechnology, in press]; here we adapt and develop the same MARIA design for MHC-I and benchmark its performance. Specifically, we used deep-learning for predicting the likelihood of neoantigen presentation trained on presented lymphoma peptides as identified by mass-spectrometry (LC-MS/MS). MARIA-I was initially trained on >47,000 ligands we previously identified by mass-spectrometry through antigen presentation profiling of patients with mantle cell lymphomas [Khodadoust et al. 2017, Nature]. Recurrent neural network (RNN) layers within MARIA-I integrate 4 key features: peptide sequence-MHC key residues relationship, peptide-MHC binding, peptide cleavage pattern, and gene expression. Results: We internally validated MARIA-I using 10-fold cross validation, where we observed an average AUC of 0.99 for the integrated model (Fig 1a); the peptide-MHC key residues relationships conferred the largest contribution to MARIA-I performance. We also further tested MARIA-I using an external dataset of ~19,000 diverse peptides from MHC-I antigen presentation profiles of four cancer cell lines (ACC1143, HCT116, HCC1937, and SUP-B15). MARIA-I maintains above 0.92 AUC across four diverse cancer types (AUC = 0.92, 0.92, 0.96, and 0.95, respectively). Since presentation of immunogenic peptides is essential for activation of T cell effector functions, we separately tested MARIA-I's ability to identify CD8 tumor infiltrating lymphocyte responses using corresponding data from 62 patients and 7587 neoantigens [Parkhurst et al. 2019, Cancer Discovery]. Despite MARIA-I not being trained on T cell reactivity data, neoantigens known to elicit positive T cell responses had significantly higher MARIA-I scores (Fig 1b, p=6.92e-5, Mann-Whitney U test). Conclusion: MARIA-I enables accurate prediction of neoantigen presentation for MHC class I at scale. Given its generalizability, we expect MARIA-I to yield insights for development of therapeutic cancer vaccines as well as applications in transplantation and autoimmune pathology. Figure 1. MARIA-I performance on antigen presentation and identifying immunogenic peptides. a) MARIA-I and sub-model predictors evaluated on 10% held-out validation set. Merging peptide sequence, gene expression, binding, and cleavage scores yielded improvements in performance as compared to each predictor's individual ability. b) MARIA-I assigns significantly higher scores to peptides known to elicit positive CD8 T cell response (p=6.92e-5, Mann-Whitney U test). Disclosures Khodadoust: Corvus Pharmaceuticals: Research Funding. Davis:Vir Biotechnology: Consultancy, Equity Ownership, Honoraria; PACT Bio: Consultancy, Equity Ownership, Honoraria; Adicet Inc: Consultancy, Equity Ownership, Honoraria; Chuga Pharmabody: Consultancy, Honoraria; Amgen: Consultancy, Research Funding; Atreca: Consultancy, Equity Ownership, Honoraria; Juno: Consultancy, Equity Ownership, Honoraria. Levy:Five Prime: Membership on an entity's Board of Directors or advisory committees; Corvus: Membership on an entity's Board of Directors or advisory committees; Quadriga: Membership on an entity's Board of Directors or advisory committees; BeiGene: Membership on an entity's Board of Directors or advisory committees; GigaGen: Membership on an entity's Board of Directors or advisory committees; Teneobio: Membership on an entity's Board of Directors or advisory committees; Sutro: Membership on an entity's Board of Directors or advisory committees; Checkmate: Membership on an entity's Board of Directors or advisory committees; Nurix: Membership on an entity's Board of Directors or advisory committees; Dragonfly: Membership on an entity's Board of Directors or advisory committees; Innate Pharma: Membership on an entity's Board of Directors or advisory committees; Abpro: Membership on an entity's Board of Directors or advisory committees; Apexigen: Membership on an entity's Board of Directors or advisory committees; Nohla: Membership on an entity's Board of Directors or advisory committees; Spotlight: Membership on an entity's Board of Directors or advisory committees; 47 Inc: Membership on an entity's Board of Directors or advisory committees; XCella: Membership on an entity's Board of Directors or advisory committees; Immunocore: Membership on an entity's Board of Directors or advisory committees; Walking Fish: Membership on an entity's Board of Directors or advisory committees. Altman:Personalis: Consultancy; Pfizer: Consultancy; Karius: Consultancy.

ATIM-28. PHASE II TRIAL OF AV-GBM-1 (AUTOLOGOUS DENDRITIC CELLS LOADED WITH TUMOR ASSOCIATED ANTIGENS) AS ADJUNCTIVE THERAPY FOLLOWING SURGERY PLUS CONCURRENT CHEMORADIATION IN NEWLY DIAGNOSED GBM PATIENTS

Abstract Newly-diagnosed glioblastoma (GBM) patients have a limited survival (18–24 months). In the last decade immunotherapy has improved survival for patients with other malignancies, but not GBM. Herein we present the design and initial enrollment results for the AV-GBM-1 single-arm phase 2 trial. The study enrolls patients with primary GBM who have undergone craniotomy, have a tumor cell culture established, and complete satisfactory leukapheresis prior to planned concurrent chemotherapy and radiation. Patients are scheduled to receive up to 8 vaccine injections at weeks 1, 2, 3, 8, 12, 16, 20 and 24. Blood samples are collected just prior to each injection. The primary endpoint is overall survival from date of enrollment for intent-to-treat with AV-GBM-1. The study has fully enrolled 26 of planned 55 patients. The cell line success rate is 30/32, with 6 in progress; successful completion of leukapheresis is 28/29. Two patients have completed all 8 doses, two discontinued after dose 3 and dose 6 because of progressive disease; 15 are currently in treatment, and 6 are about to start treatment. There have been seven SAE, all for hospitalizations related to GBM. For the first 8 treated patients, plasma samples from baseline and weeks 2, 3, and 8 have been analyzed for immune markers by RayBiotech Life Inc. using quantitative multiplex ELISA array. Markers reflecting Th1, Th2, Th17 pathways and B-cells, natural killer cells and cytotoxic T-lymphocytes increased in 7/8 patients. Principal component analysis demonstrates correlative marker groupings with early dominance of Th1/Th17 (weeks 1 and 2) followed by Th2/immunoglobulins at week 8. These findings show that these patient-specific dendritic cell vaccines are inducing pro-inflammatory responses similar to what was observed in a previous trial in melanoma. The study is progressing efficiently. Full enrollment data may be available for presentation at the time of the annual meeting.