Nevala, Wendy K.

Abstract The peripheral blood absolute lymphocyte count (ALC) on day 15 after autologous stem cell transplantation (ASCT) has been shown to be an independent predictor for overall survival (OS) for many malignancies including acute myelogenous leukemia (AML), breast cancer, multiple myeloma (MM), primary systemic amyloidosis, and Hodgkin’s and non-Hodgkin’s lymphoma (NHL). A recent report (Dean et al. BMT2005; 36, 1049–1052) suggested that infused autograft dendritic cells (DC) affect survival post-ASCT in NHL. Thus, DC recovery at day 15 post-ASCT was assessed and correlated with OS. Preliminary data from an ongoing prospective study of 28 NHL patients post-ASCT are reported. Absolute DC at day 15 was analyzed by four color flow cytometry using antibodies to CD3, CD14, CD16, and CD19. In this approach lymphocytes and DCs were initially gated by their similar forward and side light scatter characteristics; DCs were then identified as cells in this gate that lacked staining for the lymphocyte antigens CD3, CD16, and CD19 and the monocyte antigen CD14. The percentage of antigen negative cells cells in the lymphocyte gate was then multiplied by the coincident peripheral blood absolute lymphocyte to determine the absolute DC count. Survival was then analyzed using the Kaplan-Meier method. With a median follow-up of 18 months, patients recovering a DC of 10 cells/μl or above experienced superior median OS versus those who did not (not reached vs 21 months, p < 0.02, Figure 1). This study shows that an immunocompetent immune system at day 15 (not only ALC recovery, but also DC recovery) correlates with survival in NHL patients undergoing ASCT. Figure Figure

Abstract The peripheral blood absolute lymphocyte count (ALC) on day 15 after autologous stem cell transplantation (ASCT) has been shown to be an independent predictor for overall survival (OS) for many malignancies including acute myelogenous leukemia (AML), breast cancer, multiple myeloma (MM), primary systemic amyloidosis, and Hodgkin’s and non-Hodgkin’s lymphoma (NHL). However, due to the retrospective nature of previous studies, the peripheral blood lymphocyte subpopulations that predict survival are unknown. To prospectively correlate peripheral blood lymphocyte subpopulations after ASCT and progression free survival, peripheral blood lymphocytes collected from patients before and on day 15 after ASCT were analyzed by four color flow cytometry for CD3, CD4, CD8, CD16, CD 19, and CD56. Patients were then dichotomized into two groups: patients achieving normal numbers of lymphocyte subset (i.e. CD4, CD8, CD19, CD16/56) count versus those who did not. Progression free survival was then analyzed by the Kaplan-Mier method. In our cohort of 14 patients, 9 were male and 5 were female. Nine patients were diagnosed with diffuse large cell B cell lymphoma, two with mantle cell, two with follicular, and one with peripheral T cell lymphoma. On presentation, one patient had stage I, four patients had stage II, four had stage III, and five patients had stage IV disease. The median age at ASCT was 53 years (range: 26–70). The preliminary data from this ongoing prospective study of 14 patients shows that on day 15 after ASCT, 4/14 (29%) of patients achieved a normal CD3 count (median 321, range: 69–2069 cells/ml) 3/14 (21%) achieved a normal CD4 count (median 206, range: 31–1091 cells/ml), 6/14 (43%) achieved a normal CD 8 count (median 88.5, range: 13–813 cells/ml) 1/14 (7%) achieved a normal CD19 count (median 2, range:0–227 cells/ml), and 8/14 (57%) achieved a normal CD16/56 count (median 85.5, range: 10–744 cells/ml). The median follow-up was 12 months (range: 3–45 months). On univariate analysis, patients achieving an absolute NK cell count of ≥ 80 cells/μ on day 15 had significantly improved progression free survival compared to those who did not (not reached vs 3 months, p<0.006, respectively). Similar analysis evaluating the absolute CD3, CD4, CD8, and CD 19 count was not significant (p=0.1, p=0.258, p= 0.06, and p=0.55, respectively). To our knowledge, this is the first report detailing the critical role of NK cell immune reconstitution after ASCT in progression free survival. Figure Figure

Abstract Abstract Our group recently reported a Phase III clinical trial (Porrata et al. Biology of Blood and Marrow Transplantation 2016; 22: 1017-1023) demonstrating that the infusion of the autograft-absolute lymphocyte count (A-ALC) and autograft natural killer cells (A-NKC) are survival prognostic factors in non-Hodgkin lymphoma (NHL) patients treated with autologous peripheral blood hematopoietic stem cell transplantation (APBHSCT). A limitation of our Phase III clinical trial was the short-term follow-up of just two years. Therefore, we evaluated longer follow-up and assessed the role of the infused A-ALC, infused A-NKC, and peripheral blood absolute natural killer cell count (ANKC) recovery on survival post-APBHSCT. Of the 122 patients that participated in the Phase III trial, 111 patients were able to complete APBHSCT and included in the current study. With a median follow-up of 57.2 months (range: 2.1-84.6 months), superior overall survival (OS) and progression-free survival (PFS) was observed in patients infused with an A-ALC ≥ 0.5 x 109 lymphocytes/kg [OS: HR = 0.429, 95%CI, 0.128-0.828, p < 0.01; and PFS: HR = 0.456, 95% CI, 0.177-0.863, p < 0.01] and an A-NKC ≥ 0.09 x 109 cells/kg [OS: HR = 1.58e-3, 95% CI, 1.046e-6-0.179, p < 0.003; and PFS: HR= 1.58e-3, 95% CI, 7.81e-7-0.064, p < 0.003]. Furthermore, patients that maintained an ANKC ≥ 250 cells/µl at 3 months, 6 months, 9 months and 12 months post-APBHSCT also experienced superior OS (Figure 1A) and PFS (Figure 1B)[OS and PFS times in months were evaluated from infusion date of stem cells]. In the multivariate analysis a sustained ANKC ≥ 250 cells/µl was an independent predictor for OS (HR = 0.013, 95% CI, 0.001-0.063, p < 0.0001) and PFS (HR = 0.014, 95% CI, 0.001-0.067, p < 0.0001). This study is an extension of our Phase III clinical trial showing that sustained innate immunity by measuring the ANKC correlated with superior clinical outcomes; thus providing a platform to develop innate immunity immunotherapeutic strategists directing to improve clinical outcomes post-APBHSCT in NHL patients. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 464 Myeloid-derived suppressor cells (MDSC) are important, albeit incompletely characterized, immune regulatory cells which suppress host anti-tumor immunity in malignancies like melanoma. We sought to address 3 outstanding questions in the present study: i) does tumor burden drive the expansion of MDSC; ii) do MDSC express immunosuppressive B7-H family members,;iii) are MDSC depleted following chemotherapy administration. As MDSC expand in response to tumor-derived factors, including those elevated in melanoma patients, we hypothesized that the frequency of MDSC present in the peripheral blood of melanoma patients may be dependent on tumor stage. Therefore, PBMC were obtained from both normal donors and melanoma patients with all stages of disease (stage I, n=10; stage II, n=10; stage III, n=10; stage IV, n=47). A discreet population of CD14+HLA-DR-/lo MDSC was appreciated in samples obtained from melanoma patients, but was largely absent in normal donors. Approximately 0.5% of PBMC were CD14+HLA-DR-/lo in normal donors. In contrast, the frequency of these cells progressively increased with tumor stage in melanoma. While a two-fold increase in CD14+HLA-DR-/lo MDSC was observed in stage I patients, this difference did not reach statistical significance. In contrast, a significant increase in CD14+HLA-DR-/lo MDSC was observed in patients with stage II-IV disease (2.2% Stage II, p<.01; 3.4% stage III, p<.001; 13.2% stage IV, p<.001). While the observed range (range: 0.8-66.3%) in frequency of CD14+HLA-DR-/lo MDSC was broad in stage IV melanoma, these cells comprised more than 10% of total PBMC in the majority of patients. Various B7 homologues (e.g. B7-H1, B7-H2, B7-H3 and B7-H4) may inhibit T-cell activation, proliferation and cytokine production or promote the induction of T-cell apoptosis and unresponsiveness. Due to their immunosuppressive affects, and expression by tumor cells or immune regulatory cells (e.g. Treg, MDSC), these B7-H members are associated with adverse outcomes in multiple human malignancies. As the expression of these important immunoregulatory molecules on MDSC is unknown, we sought to determine whether CD14+HLA-DR-/lo MDSC in melanoma may express B7-H family members. Therefore, PBMC from patients with metastatic melanoma were stained with either an isotype control or antibodies against B7-H1, B7-H2, B7-H3 or B7-H4. In all cases, B7-H family members were more highly expressed on CD14+HLA-DR-/lo MDSC when compared with the expression observed on CD14+ cells from normal donors. While B7-H1 (p<.01), B7-H2 (p<.001) and B7-H4 (p<.01) were preferentially expressed on HLA-DR-/lo cells in melanoma patients, B7-H3 was more highly expressed on both HLA-DR+ (p<.05) and HLA-DR-/lo (p<.001) CD14+ cells. Serial blood samples, both at baseline and at least 12 weeks after therapy, were availabel for 10 patients with metastatic melanoma undergoing therapy wither either carboplatin and nanoparticle albumin bound paclitaxel (nab paclitaxel; n=6) or carboplatin, paclitaxel and bevacizumab (n=4). The frequency of both CD14+HLA-DR-/lo MDSC and conventional CD14+HLA-DR+ monocytes was determined both before and after chemotherapy. An approximately 50% reduction in the frequency of CD14+HLA-DR-/lo MDSC was observed following chemotherapy (p=.004), with no significant reduction in the frequency of conventional HLA-DR+ monocytes (p=.08). Collectively, the data presented implicates multiple B7-H family members in MDSC-mediated immune suppression and demonstrates that the expansion of B7-H+CD14+HLA-DR-/lo MDSC in melanoma is directly associated with the tumor burden, but may be abrogated by the administration of taxane-based chemotherapy. Disclosures: No relevant conflicts of interest to declare.

e21058 Background: Recent clinical advances in cancer immuno-therapeutics underscore the need for improved understanding of the complex relationship between cancer and the multiple, multi-functional, inter-dependent, cellular and humoral mediators/regulators of the human immune system. This will lead to improvements in the efficacy of existing immune therapies (patient selection; drug combinations) and insight into new therapeutic targets that may significantly reduce the time to new therapeutics discoveries capable of meaningful clinical impacts. Methods: A systems analysis approach (Cancer Immune Control Dynamics, CICD) attempts to identify the differences between systemic immune homeostasis of healthy volunteers versus patients with metastatic malignant melanoma based on serial measurements of a set of conventional peripheral blood biomarkers of immune function (15 cell subsets and 35 cytokines) assessed daily over 7-10 days. The modeling strategy takes aerospace engineering control theory and system identification algorithms to analyze the state of an individual’s immune system based on the biomarkers’ dynamic non-linear oscillatory behaviors. The analysis framework builds on the classical predator-prey equations commonly used to model biological system dynamics. Tens of thousands of biologically possible biomarker interactions are modeled by a set of matrix equations that creates a system interaction model. CICD quantifies the system equations with biomarker values and solves it to measure the interactions. Results: Quantification of thousands of unique biomarker relationships per participant enables classification based on their immune profile rather than their clinical diagnosis and a basis for a visualization of a person’s immunity state. Conclusions: Results provide initial evidence that a model-based analysis of serially collected biomarker data can lead to biological insights into human immunity, of potential benefit in clinical decisions. It is anticipated that CICD-based capabilities will provide tools to specifically address cancer and treatment modulated (immune checkpoint inhibitors) parameters of human immunity, revealing clinically relevant biological interactions.

Abstract Despite unprecedented successes with immune checkpoint blockade in advanced cancers, these agents provide durable clinical benefit in only a subset of patients. In addition, the clinical management of patients receiving immune checkpoint blockade remains quite challenging due to the unpredictable and kinetically heterogeneous responses which can manifest as late responses, pseudoprogression, or hyperprogression in subsets of patients. The dynamics and heterogeneity of programmed cell death protein ligand 1 (PD-L1, aka B7-H1) expression confound its use as a predictive biomarker in cancer immunotherapy, but blood-based biomarkers have the potential to predict responders and detect mechanisms of resistance to immunotherapy. We previously reported that Bim (BH3-only protein) is a downstream signaling molecule of the PD-1 pathway, and that Bim levels in circulating tumor-reactive T-cells reflected patient responses to anti-PD-1 therapy in melanoma. We also discovered the existence of soluble PD-L1 (sPD-L1) in the plasma of cancer patients and showed a correlation of sPD-L1 with cancer stages in renal cell carcinoma and with prognosis in metastatic melanoma. Here we evaluated the frequency of tumor-reactive T cells with Bim expression along with effector memory profile and sPD-L1 as biomarkers of response in a new cohort of patients with metastatic melanoma and lung cancer undergoing anti-PD-1 therapy. We recruited 100 cancer patients treated with anti-PD-1 therapy who had peripheral blood collected at baseline and at each subsequent radiographic tumor evaluation. Frequencies of Bim+ and effector memory CD8+ T cells were measured by flow cytometry in gated tumor-reactive CD11a high PD1+ CD8+ T cells. We also measured levels of sPD-L1 in plasma at baseline and serially during treatment with ELISA. Baseline T cell markers and sPD-L1 levels and their percent changes in patients who had a radiographic response were compared to those who had progressive disease (PD). We found that patients with objective response after 4 cycles of anti-PD-1 therapy had higher frequency of Bim+ CD8+ T cells at baseline compared to patients with PD (mean 43% vs. 30%, P=0.0484). The frequencies of Bim+ T cells decreased significantly after the first 3 months of treatment in responders compared with progressors (mean -16% vs. + 40% P=0.0111). The frequency of effector memory CD8+ T cells also dramatically increased in responders in 3-6 months after anti-PD-1 therapy (mean 89% vs. 9.56%, p=0.002). High baseline sPD-L1 was associated with progression on anti-PD-1 therapy (mean 2.8 ng/mL vs. 0.7 ng/mL, p=0.07) or development of immune-related toxicities and the levels increased by 12 weeks in patients progressing on therapy. Conclusion: Measurements of T cell biomarkers (Bim and effector memory) and sPD-L1 levels provide a new noninvasive way to predict and monitor patient responses to anti-PD-1 monotherapy in melanoma and lung cancers. Note: This abstract was not presented at the conference. Citation Format: Roxana S. Dronca, Aaron Mansfield, Xin Liu, Susan Harrington, Elizabeth Enninga, Svetomir Markovic, Lisa Kottschade, Rob Mcwilliams, Matthew Block, Wendy Nevala, Michael Thompson, Haidong Dong. Blood-based T cell biomarkers and soluble PD-L1 predict responses and immune-related toxicity to PD-1 blockade in melanoma and lung cancer [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2017 Oct 1-4; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2018;6(9 Suppl):Abstract nr A38.

A vaccine that could expand melanoma-specific T cells might reduce the risk of recurrence of resected melanoma and could provide an alternative or adjunct to standard immunotherapy options. We tested the safety and immunogenicity of a vaccine coupling a melanoma-associated peptide with a xenogenic peptide (to promote epitope spreading) and/or resiquimod (to activate antigen-presenting cells). HLA-A2-positive patients with resected stage II, III, and IV melanoma were assigned to treatment on one of three schedules. All patients received three subcutaneous doses of the peptide MART-1a mixed with Montanide. In addition, patients on schedule 1 received the xenoantigen peptide Gag267–274, patients on schedule 2 received topical resiquimod, and patients on schedule 3 received both Gag267–274 and resiquimod. Blood samples were tested for the frequency of antigen-specific T cells by tetramer assay, as well as immune cell subtypes and plasma cytokine levels. Patients enrolled from October 2012 to December 2014, with 10 patients enrolling to each schedule. The most common adverse events were injection site reaction (26 patients) and fatigue (15 patients). Tetramer analysis revealed antigen-specific responses (defined as doubling of MART-1a-specific T cells from pretreatment to post-treatment) in 20, 60, and 40% of patients treated on schedules 1, 2, and 3, respectively. Vaccine treatment consisting of MART-1a peptide, Gag267–274, Montanide, and topical resiquimod was well-tolerated. The addition of the Gag267–274 xenoantigen was not associated with an increase in the response to MART-1a, whereas use of topical resiquimod was associated with a higher frequency of MART-1a-specific T-cell responses that did not meet statistical significance.