An Allogeneic Multiple Myeloma GM-CSF-Secreting Vaccine with Lenalidomide Induces Long-term Immunity and Durable Clinical Responses in Patients in Near Complete Remission.

PURPOSE: This proof-of-principle clinical trial evaluated whether an allogeneic multiple myeloma GM-CSF-secreting vaccine (MM-GVAX) in combination with lenalidomide could deepen the clinical response in patients with multiple myeloma in sustained near complete remission (nCR). PATIENTS AND METHODS: Fifteen patients on lenalidomide were treated with MM-GVAX and pneumococcal conjugate vaccine (PCV; Prevnar) at 1, 2, 3, and 6 months. RESULTS: Eight patients (53.3%) achieved a true CR. With a median follow-up of 5 years, the median progression-free survival had not been reached, and the median overall survival was 7.8 years from enrollment. MM-GVAX induced clonal T-cell expansion and measurable cytokine responses that persisted up to 7 years in all patients. At baseline, a higher minimal residual disease was predictive of early relapse. After vaccination, a lack of both CD27-DNAM1-CD8+ T cells and antigen-presenting cells was associated with disease progression. CONCLUSIONS: MM-GVAX, along with lenalidomide, effectively primed durable immunity and resulted in long-term disease control, as suggested by the reappearance of a detectable, fluctuating M-spike without meeting the criteria for clinical relapse. For patients in a nCR, MM-GVAX administration was safe and resulted in prolonged clinical responses.

Bifunctional immune checkpoint-targeted antibody-ligand traps that simultaneously disable TGFß enhance the efficacy of cancer immunotherapy.

A majority of cancers fail to respond to immunotherapy with antibodies targeting immune checkpoints, such as cytotoxic T-lymphocyte antigen-4 (CTLA-4) or programmed death-1 (PD-1)/PD-1 ligand (PD-L1). Cancers frequently express transforming growth factor-ß (TGFß), which drives immune dysfunction in the tumor microenvironment by inducing regulatory T cells (Tregs) and inhibiting CD8+ and TH1 cells. To address this therapeutic challenge, we invent bifunctional antibody-ligand traps (Y-traps) comprising an antibody targeting CTLA-4 or PD-L1 fused to a TGFß receptor II ectodomain sequence that simultaneously disables autocrine/paracrine TGFß in the target cell microenvironment (a-CTLA4-TGFßRIIecd and a-PDL1-TGFßRIIecd). a-CTLA4-TGFßRIIecd is more effective in reducing tumor-infiltrating Tregs and inhibiting tumor progression compared with CTLA-4 antibody (Ipilimumab). Likewise, a-PDL1-TGFßRIIecd exhibits superior antitumor efficacy compared with PD-L1 antibodies (Atezolizumab or Avelumab). Our data demonstrate that Y-traps counteract TGFß-mediated differentiation of Tregs and immune tolerance, thereby providing a potentially more effective immunotherapeutic strategy against cancers that are resistant to current immune checkpoint inhibitors.

Flow cytometric discrimination of seven lineage markers by using two fluorochromes.

Flow cytometry is the primary immunological technique used to analyze multiple parameters on complex cell populations. We present a staining method that identifies major human mononuclear lymphoid and myeloid populations (CD4+ and CD8+ T cells, γδ T cells, B cells, NK cells and monocytes), using only two fluorochromes and a minimal number of cells. Our approach increases the number of markers recordable on most flow cytometers allowing for a deeper and more comprehensive immunophenotyping.

High-dose granulocyte-macrophage colony-stimulating factor-producing vaccines impair the immune response through the recruitment of myeloid suppressor cells.

Tumor vaccines have shown promise in early clinical trials. Among them, tumor cells genetically engineered to secrete biologically active granulocyte-macrophage colony-stimulating factor (GM-CSF) can generate a systemic antitumor immune response. Although the minimal required GM-CSF dose produced by modified tumor cells to achieve a measurable antitumor effect is well known, no data examined whether an upper therapeutic limit may exist for this vaccination strategy. Because recent data demonstrate an immunosuppressive effect of GM-CSF produced by growing tumors, we thus sought to determine whether high GM-CSF doses administered in a vaccine formulation could impair antitumor immunity. Using a vaccine strategy involving a GM-CSF-producing bystander cell line (B78H1-GM) admixed with autologous tumor, we assessed the impact of varying doses of GM-CSF while maintaining a constant antigen dose. Our results defined a threshold above which a GM-CSF-based vaccine not only lost its efficacy, but more importantly for its clinical implications resulted in substantial immunosuppression in vivo. Above this threshold, GM-CSF induced Gr1+/CD11b+ myeloid suppressor cells that substantially impaired antigen-specific T-cell responses and adversely affected antitumor immune responses in vivo. The dual effects of GM-CSF are mediated by the systemic and not local concentration of this cytokine. Myeloid suppressor cell-induced immunosuppression is mediated by nitric oxide production via inducible nitric oxide synthase (iNOS) because the specific iNOS inhibitor, l-NMMA, restored antigen-specific T-cell responsiveness in vitro. Taken together, our data demonstrated the negative impact of supra-therapeutic vaccine doses of GM-CSF and underscored the importance of identifying these critical variables in an effort to increase the therapeutic efficacy of tumor vaccines.

Marrow-Infiltrating Lymphocytes - Role in Biology and Cancer Therapy.

The past several years have witnessed the acceptance of immunotherapy into the mainstream of therapies for patients with cancer. This has been driven by the clinical successes of antibodies to the checkpoint inhibitors, CTLA-4 and PD-1, capable of imparting long-term remissions in several solid tumors as well as Hodgkin's lymphoma (1) and the therapeutic successes of adoptive T-cell transfer with chimeric antigen receptors (2) or modified T-cell receptors (3) that have mostly utilized peripheral T-cells. One emerging area of therapeutic T cell intervention has been the utilization of marrow-infiltrating lymphocytes (MILs) - a novel form of adoptive T-cell therapy. This approach was initially developed to increase the likelihood of a precursor T-cell population with an enhanced tumor specificity in bone marrow (BM)-derived malignancies. However, the unique attributes of BM T-cells and their interaction with their microenvironment provide significant rationale to utilize these cells therapeutically in diseases that extend beyond hematologic malignancies.

Marrow Infiltrating Lymphocytes: Their Role in Adoptive Immunotherapy.

The clinical results achieved with immunotherapy in the past few years have now firmly established it within the cancer armamentarium. Our group has explored a novel approach to adoptive T-cell therapy utilizing marrow-infiltrating lymphocytes (MILs) initially developed with the concept of utilizing a population of T cells with a higher endogenous tumor specificity. Marrow-infiltrating lymphocytes are antigen-experienced T cells that home to and remain in the bone marrow (BM) because of the unique biology of the BM microenvironment. Marrow-infiltrating lymphocytes can easily be obtained from the BM and can be expanded to demonstrate enhanced antigen specificity. Current clinical trials utilize MILs for patients with myeloma as well as patients with relapsed disease following an allogeneic transplant. Ongoing preclinical work is currently evaluating MILs for use in solid cancers as well as pediatric cancers. The examination of a MIL as a source cell for chimeric antigen receptor T or transgenic cell receptor is also in the preclinical stages. Until now, for both chimeric antigen receptor T-cell therapy and transgenic cell receptor T-cell therapy, the target cell of choice has included peripheral blood. The unique antigen-experienced properties of MILs may make them the ideal source of cell for gene modification strategies. Therefore, MILs are a distinctive set of T cells that have been shaped by the unique BM microenvironment and may play a future role as a novel immunotherapy for hematologic malignancies.

Adoptive transfer of activated marrow-infiltrating lymphocytes induces measurable antitumor immunity in the bone marrow in multiple myeloma.

Successful adoptive T cell therapy (ACT) requires the ability to activate tumor-specific T cells with the ability to traffic to the tumor site and effectively kill their target as well as persist over time. We hypothesized that ACT using marrow-infiltrating lymphocytes (MILs) in multiple myeloma (MM) could impart greater antitumor immunity in that they were obtained from the tumor microenvironment. We describe the results from the first clinical trial using MILs in MM. Twenty-five patients with either newly diagnosed or relapsed disease had their MILs harvested, activated and expanded, and subsequently infused on the third day after myeloablative therapy. Cells were obtained and adequately expanded in all patients with anti-CD3/CD28 beads plus interleukin-2, and a median of 9.5 × 10(8) MILs were infused. Factors indicative of response to MIL ACT included (i) the presence of measurable myeloma-specific activity of the ex vivo expanded product, (ii) low endogenous bone marrow T cell interferon-γ production at baseline, (iii) a CD8(+) central memory phenotype at baseline, and (iv) the generation and persistence of myeloma-specific immunity in the bone marrow at 1 year after ACT. Achieving at least a 90% reduction in disease burden significantly increased the progression-free survival (25.1 months versus 11.8 months; P = 0.01). This study demonstrates the feasibility and efficacy of MILs as a form of ACT with applicability across many hematologic malignancies and possibly solid tumors infiltrating the bone marrow.

Tadalafil augments tumor specific immunity in patients with head and neck squamous cell carcinoma.

PURPOSE: To determine if phosphodiesterase 5 (PDE5) inhibitors can augment immune function in patients with head and neck cancer through inhibition of myeloid-derived suppressor cells (MDSC). EXPERIMENTAL DESIGN: We performed a randomized, prospective, double blinded, placebo controlled, phase II clinical trial to determine the in vivo effects of systemic PDE5 inhibition on immune function in patients with head and neck squamous cell carcinoma (HNSCC). RESULTS: Tadalafil augmented immune response, increasing ex vivo T-cell expansion to a mean 2.4-fold increase compared with 1.1-fold in control patients (P = 0.01), reducing peripheral MDSC numbers to mean 0.81-fold change compared with a 1.26-fold change in control patients (P = 0.001), and increasing general immunity as measured by delayed type hypersensitivity response (P = 0.002). Tumor-specific immunity in response to HNSCC tumor lysate was augmented in tadalafil-treated patients (P = 0.04). CONCLUSIONS: These findings demonstrate that tadalafil augments general and tumor-specific immunity in patients with HNSCC and has therapeutic potential in HNSCC. Evasion of immune surveillance and suppression of systemic and tumor-specific immunity is a significant feature of head and neck cancer development. This study demonstrates that a PDE5 inhibitor, tadalafil, can reverse tumor-specific immune suppression in patients with head and neck cancer, with potential for therapeutic application.

Targeting immune suppression with PDE5 inhibition in end-stage multiple myeloma.

Myeloid-derived suppressor cells (MDSC) play a significant role in tumor-induced immune suppression. Targeting their function could improve antitumor therapies. Previously, we demonstrated that phosphodiesterase 5 (PDE5) inhibition in MDSCs augmented antitumor immunity in murine models. Here, we show how the addition of the PDE5 inhibitor, tadalafil, in a patient with end-stage relapsed/refractory multiple myeloma reduced MDSC function and generated a dramatic and durable antimyeloma immune and clinical response. Strategies targeting MDSC function with PDE5 inhibitors represent a novel approach that can augment the efficacy of tumor-directed therapies.