Paul Neeson

Mechanism of action of immunomodulatory drugs (IMiDS) in multiple myeloma

Immunomodulatory drugs (IMiDs) are thalidomide analogues, which possess pleiotropic anti-myeloma properties including immune-modulation, anti-angiogenic, anti-inflammatory and anti-proliferative effects. Their development was facilitated by an improved understanding in myeloma (MM) biology and initiated a profound shift in the therapeutic approach towards MM. Despite the diverse effects of IMiDs in vitro, the relative contribution of each effect towards their ultimate anti-MM activity is still unclear. Based on in vitro data, it appears that anti-proliferative effects and downregulation of crucial cytokines are their most important anti-MM attributes. Although the co-stimulatory effects on T and NK cells have been heralded as a unique and important property of IMiDs towards enhancing anti-MM immune activity, these in vitro effects have yet to be firmly corroborated in vivo. Much is yet to be elucidated regarding the complex interplay of immunomodulatory cytokines that occurs in vivo, which ultimately dictates the net effects of IMiDs in MM—the understanding of which is necessary to facilitate optimal manipulation of these drugs in future MM management.

Persistence and Efficacy of Second Generation CAR T Cell Against the LeY Antigen in Acute Myeloid Leukemia

In a phase I study of autologous chimeric antigen receptor (CAR) anti-LeY T-cell therapy of acute myeloid leukemia (AML), we examined the safety and postinfusion persistence of adoptively transferred T cells. Following fludarabine-containing preconditioning, four patients received up to 1.3 × 109 total T cells, of which 14-38% expressed the CAR. Grade 3 or 4 toxicity was not observed. One patient achieved a cytogenetic remission whereas another with active leukemia had a reduction in peripheral blood (PB) blasts and a third showed a protracted remission. Using an aliquot of In111-labeled CAR T cells, we demonstrated trafficking to the bone marrow (BM) in those patients with the greatest clinical benefit. Furthermore, in a patient with leukemia cutis, CAR T cells infiltrated proven sites of disease. Serial PCR of PB and BM for the LeY transgene demonstrated that infused CAR T cells persisted for up to 10 months. Our study supports the feasibility and safety of CAR-T-cell therapy in high-risk AML, and demonstrates durable in vivo persistence.

The immunostimulatory effect of lenalidomide on NK-cell function is profoundly inhibited by concurrent dexamethasone therapy

Lenalidomide combined with dexamethasone is an effective treatment for refractory/relapsed multiple myeloma (MM). Lenalidomide stimulates natural killer (NK) cells and enhances antitumor responses. We assessed NK cell number and function in 25 patients with MM participating in a clinical trial of lenalidomide and dexamethasone. NK cell numbers increased from a mean of 2.20 ± 0.05 × 10(5)/mL (baseline) to a mean of 3.90 ± 0.03 × 10(5)/mL (cycle 6; P = .05); however, in vitro NK-cell-mediated cytotoxicity decreased from 48.9% ± 6.8% to 27.6% ± 5.1% (P = .0028) and could not be rescued by lenalidomide retreatment. Lenalidomide increased normal donor NK-cell cytotoxicity in vitro from 38.5% to 53.3%, but this was completely abrogated by dexamethasone. Dexamethasone suppression of NK cell-mediated cytotoxicity was partially reversed by a 3-day washout, but these cells remained refractory to lenalidomide-induced enhanced function. Lymphocyte subset depletion experiments revealed that lenalidomides enhancement of NK cell-mediated cytotoxicity was mediated by CD4(+) T-cell production of interleukin 2 and that dexamethasone acted by suppressing interleukin-2 production. Similarly, the reduced ability of NK cells from patients with MM to respond to lenalidomide was also due to impaired CD4 T-cell function. Our findings indicate that lenalidomide immunostimulatory effects on patient NK cells are severely blunted by concurrent dexamethasone administration.

A high rate of durable responses with romidepsin, bortezomib, and dexamethasone in relapsed or refractory multiple myeloma

We report results from a study exploring the combination of romidepsin, bortezomib, and dexamethasone for the treatment of patients with multiple myeloma (MM) previously treated with > 1 prior therapy. The primary objective was to determine the maximum tolerated dose (MTD) of the combination using a novel accelerated dose-escalation schedule in patients with relapsed or refractory MM. The secondary objective was to determine overall response (OR), time to progression (TTP), and overall survival (OS). The MTD identified was bortezomib 1.3 mg/m(2) (days 1, 4, 8, and 11), dexamethasone 20 mg (days 1, 2, 4, 5, 8, 9, 11, and 12), and romidepsin 10 mg/m(2) (days 1, 8, and 15) every 28 days. Thrombocytopenia (64%) was the most common ≥ grade 3 hematologic toxicity. Peripheral neuropathy occurred in 76% of patients (n = 19) (≥ grade 3, 8%; 95% confidence interval [CI] 1%-26%). Maintenance romidepsin 10 mg/m(2) (on days 1 and 8 of a 28-day cycle) proved feasible, with 12 patients receiving a median of 7.5 cycles (range: 1-29). An OR (M-protein) of > minor response (MR) was seen in 18 of 25 patients (72%); 2 (8%) had complete remissions (CRs) and 13 (52%) had partial responses (PRs), including 7 (28%) with very good PRs (VGPRs). The median TTP was 7.2 (95% CI: 5.5-19.6) months, and the median OS was > 36 months. This regimen shows activity with manageable toxicity and warrants further evaluation. This trial was registered at www.clinicaltrials.gov as NCT00431990.

Gene-modified T cells as immunotherapy for multiple myeloma and acute myeloid leukemia expressing the Lewis Y antigen.

We have evaluated the carbohydrate antigen LewisY (LeY) as a potential target for T-cell immunotherapy of hematological neoplasias. Analysis of 81 primary bone marrow samples revealed moderate LeY expression on plasma cells of myeloma patients and myeloblasts of patients with acute myeloid leukemia (AML) (52 and 46% of cases, respectively). We developed a retroviral vector construct encoding a chimeric T-cell receptor that recognizes the LeY antigen in a major histocompatibility complex-independent manner and delivers co-stimulatory signals to achieve T-cell activation. We have shown efficient transduction of peripheral blood-derived T cells with this construct, resulting in antigen-restricted interferon-γ secretion and cell lysis of LeY-expressing tumor cells. In vivo activity of gene-modified T cells was demonstrated in the delayed growth of myeloma xenografts in NOD/SCID mice, which prolonged survival. Therefore, targeting LeY-positive malignant cells with T cells expressing a chimeric receptor recognizing LeY was effective both in vitro and in a myeloma mouse model. Consequently, we plan to use T cells manufactured under Good Manufacturing Practice conditions in a phase I immunotherapy study for patients with LeY-positive myeloma or AML.

CMTM6 maintains the expression of PD-L1 and regulates anti-tumour immunity

Cancer cells exploit the expression of the programmed death-1 (PD-1) ligand 1 (PD-L1) to subvert T-cell-mediated immunosurveillance. The success of therapies that disrupt PD-L1-mediated tumour tolerance has highlighted the need to understand the molecular regulation of PD-L1 expression. Here we identify the uncharacterized protein CMTM6 as a critical regulator of PD-L1 in a broad range of cancer cells, by using a genome-wide CRISPR–Cas9 screen. CMTM6 is a ubiquitously expressed protein that binds PD-L1 and maintains its cell surface expression. CMTM6 is not required for PD-L1 maturation but co-localizes with PD-L1 at the plasma membrane and in recycling endosomes, where it prevents PD-L1 from being targeted for lysosome-mediated degradation. Using a quantitative approach to profile the entire plasma membrane proteome, we find that CMTM6 displays specificity for PD-L1. Notably, CMTM6 depletion decreases PD-L1 without compromising cell surface expression of MHC class I. CMTM6 depletion, via the reduction of PD-L1, significantly alleviates the suppression of tumour-specific T cell activity in vitro and in vivo. These findings provide insights into the biology of PD-L1 regulation, identify a previously unrecognized master regulator of this critical immune checkpoint and highlight a potential therapeutic target to overcome immune evasion by tumour cells.

Tumor Ablation by Gene-Modified T Cells in the Absence of Autoimmunity

Adoptive immunotherapy involving genetic modification of T cells with antigen-specific, chimeric, single-chain receptors is a promising approach for the treatment of cancer. To determine whether gene-modified T cells could induce antitumor effects without associated autoimmune pathology, we assessed the ability of T cells expressing an anti-Her-2 chimeric receptor to eradicate tumor in Her-2 transgenic mice that express human Her-2 as a self-antigen in brain and mammary tissues. In adoptive transfer studies, we demonstrated significant improvement in the survival of mice bearing Her-2(+) 24JK tumor following administration of anti-Her-2 T cells compared with control T cells. The incorporation of a lymphoablative step prior to adoptive transfer of anti-Her-2 T cells and administration of IL-2 were both found to further enhance survival. The reduction in tumor growth was also correlated with localization of transferred T cells at the tumor site. Furthermore, an antigen-specific recall response could be induced in long-term surviving mice following rechallenge with Her-2(+) tumor. Importantly, antitumor effects were not associated with any autoimmune pathology in normal tissue expressing Her-2 antigen. This study highlights the therapeutic potential of using gene-engineered T cells as a safe and effective treatment of cancer.

Tumor sensitivity to IFN-γ is required for successful antigen-specific immunotherapy of a transplantable mouse tumor model for HPV-transformed tumors

Purpose: Many human tumors lose responsiveness to IFN-γ, providing a possible mechanism for the tumor to avoid immune recognition and destruction. Here we investigate the importance of tumor responsiveness to IFN-γ in the successful immunotherapy of TC1 tumors that were immortalized with human papillomavirus proteins E6 and E7. Methods: To investigate the role of IFN-γ in vivo, we constructed a variant of TC1, TC1.mugR, that is unresponsive to IFN-γ due to overexpression of a dominant negative IFN-γ receptor. Results: Using recombinant Listeria monocytogenes that express HPV-16 E7 (Lm-LLO-E7) to stimulate an antitumor response, we demonstrate that sensitivity to IFN-γ is required for therapeutic efficacy in that Lm-LLO-E7 induces regression of TC1 tumors but not TC1.mugR. In addition, we show that tumor sensitivity to IFN-γ is not required for inhibition of tumor angiogenesis by Lm-LLO-E7 or for trafficking of CD4+ and CD8+ T cells to the tumor. However, it is required for penetration of lymphocytes into the tumor mass in vivo. Conclusions: Our findings identify a role for IFN-γ in immunity to TC1 tumors and show that loss of tumor responsiveness to IFN-γ poses a challenge to antigen-based immunotherapy.

The level of glycolytic metabolism in acute myeloid leukemia blasts at diagnosis is prognostic for clinical outcome

This research investigated the level of glycolytic metabolism in leukemic blasts as a prognostic marker in AML. Using an in vitro dye‐reduction assay, we determined the level of glycolytic metabolism in 26 BM samples taken from 23 adult patients with newly diagnosed (n=19) or relapsed (n=4) AML, and AML blasts stratified into two distinct cohorts of moderate (<70%) or high (>80%) levels of glycolytic metabolism. All samples taken at relapse were moderately glycolytic. However, nine of the 19 samples taken at diagnosis were highly glycolytic, and 10 were moderately glycolytic. Three patients had paired samples taken at diagnosis and relapse, and the glycolytic metabolism of these samples did not alter between the two time‐points. The level of glycolytic metabolism did not correlate with the percentage of marrow blasts, patient age, or CG/molecular risk group. Highly glycolytic AML blasts were more resistant to apoptosis induced by ATRA and/or ATO in vitro, suggesting potential resistance to induction chemotherapy, as has been observed in solid tumors. Despite this, high levels of glycolytic metabolism at diagnosis were predictive of a significantly improved duration of CR1 and OS following AML remission induction chemotherapy. In conclusion, we found that the extent of myeloblast glycolysis may be an effective and easily applied method to determine the pretreatment prognosis of AML.

CD3 bright signals on γδ T cells identify IL-17A-producing Vγ6Vδ1 + T cells

Interleukin‐17A (IL‐17A) is a pro‐inflammatory cytokine that has an important role at mucosal sites in a wide range of immune responses including infection, allergy and auto‐immunity. γδ T cells are recognized as IL‐17 producers, but based on the level of CD3 expression, we now define the remarkable ability of a CD3bright γδ T‐cell subset with an effector memory phenotype to rapidly produce IL‐17A, but not interferon‐γ. CD3bright γδ T cells uniformly express the canonical germline encoded Vγ6/Vδ1+ T‐cell receptor. They are widely distributed with a preferential representation in the lungs and skin are negatively impacted in the absence of retinoic acid receptor‐related orphan receptor gammat expression or endogenous flora. This population responded rapidly to various stimuli in a mechanism involving IL‐23 and NOD‐like receptor family, pyrin domain containing 3 (NLRP3)‐inflammasome‐dependent IL‐1β. Finally, we demonstrated that IL‐17‐producing CD3bright γδ T cells responded promptly and strongly to pneumococcal infection and during skin inflammation. Here, we propose a new way to specifically analyze IL‐17‐producing Vγ6/Vδ1+ T cells based on the level of CD3 signals. Using this gating strategy, our data reinforce the crucial role of this γδ T‐cell subset in respiratory and skin disorders.