Pembrolizumab Enhances the Anti-Leukemia Activity of Antigen Specific Cytotoxic T Lymphocytes

https://openworks.mdanderson.org/sumexp23/1074/thumbnail.jp

A novel TCR-like CAR with specificity for PR1/HLA-A2 effectively targets myeloid leukemia in vitro when expressed in human adult peripheral blood and cord blood T cells

Background aims The PR1 peptide, derived from the leukemia-associated antigens proteinase 3 and neutrophil elastase, is overexpressed on HLA-A2 in acute myeloid leukemia (AML). We developed a T-cell receptor (TCR)-like monoclonal antibody (8F4) that binds the PR1/HLA-A2 complex on the surface of AML cells, efficiently killing them in vitro and eliminating them in preclinical models. Humanized 8F4 (h8F4) with high affinity for the PR1/HLA-A2 epitope was used to construct an h8F4- chimeric antigen receptor (CAR) that was transduced into T cells to mediate anti-leukemia activity. Methods Human T cells were transduced to express the PR1/HLA-A2-specific CAR (h8F4-CAR-T cells) containing the scFv of h8F4 fused to the intracellular signaling endo-domain of CD3 zeta chain through the transmembrane and intracellular costimulatory domain of CD28. Results Adult human normal peripheral blood (PB) T cells were efficiently transduced with the h8F4-CAR construct and predominantly displayed an effector memory phenotype with a minor population (12%) of central memory cells in vitro. Umbilical cord blood (UCB) T cells could also be efficiently transduced with the h8F4-CAR. The PB and UCB-derived h8F4-CAR-T cells specifically recognized the PR1/HLA-A2 complex and were capable of killing leukemia cell lines and primary AML blasts in an HLA-A2-dependent manner. Conclusions Human adult PB and UCB-derived T cells expressing a CAR derived from the TCR-like 8F4 antibody rapidly and efficiently kill AML in vitro. Our data could lead to a new treatment paradigm for AML in which targeting leukemia stem cells could transfer long-term immunity to protect against relapse

Vaccination of metastatic renal cell carcinoma patients with autologous tumour-derived vitespen vaccine: clinical findings

The aim of this study was to evaluate the clinical efficacy as determined by time to progression and response rate (RR) of autologous vitespen (formerly HSPPC-96; Oncophage, Antigenics Inc., New York, NY, USA) with and without interleukin-2 (IL-2; Proleukin: Chiron, Emoryville, CA, USA) in stage IV metastatic renal cell carcinoma (RCC) patients undergoing nephrectomy. Eighty-four patients were enrolled on study, and then underwent nephrectomy and harvest of tumour tissue for use in autologous vaccine manufacture. Initial treatment schedule started approximately 4 weeks after surgery and consisted of six injections: once weekly for 4 weeks, then two injections biweekly (vaccines administered at weeks 1, 2, 3, 4, 6, 8), followed by restaging at or around week 10. Patients who had stable or responsive disease continued to receive vaccine, with four more vaccinations biweekly (at weeks 10, 12, 14, 16). Patients who had progressive disease at week-10 evaluation received four consecutive 5-day-per-week courses of 11 × 106 U of IL-2 subcutaneously (weeks 10, 11, 12, 13), with four doses of vitespen at 2-week intervals (at weeks 10, 12, 14, 16). At the next evaluation (week 18), patients with a complete response received two further cycles of vitespen (with IL-2 if also received during prior cycle) or until vaccine supply was exhausted. Patients with stable disease or partial response repeated their prior cycle of therapy. Disease progressors who had not yet received IL-2 began IL-2 treatment, and progressors who had already received IL-2 came off study. Of 60 evaluable patients, 2 demonstrated complete response (CR), 2 showed partial response (PR), 7 showed stable disease, and 33 patients progressed. Sixteen patients had unconfirmed stable disease. Two patients who progressed on vaccine alone experienced disease stabilisation when IL-2 was added. Treatment with vitespen did not result in a discernable benefit in the majority of patients with metastatic RCC treated in this study. Use in combination with immunoregulatory agents may enhance the efficacy of vitespen

Peptide/MHC Tetramer-Based Sorting of CD8+ T Cells to a Leukemia Antigen Yields Clonotypes Drawn Nonspecifically from an Underlying Restricted Repertoire

Testing of T cell-based cancer therapeutics often involves measuring cancer antigen-specific T-cell populations with the assumption that they arise from in vivo clonal expansion. This analysis, using peptide/MHC tetramers, is often ambiguous

Recent developments in immunotherapy of acute myeloid leukemia

The advent of new immunotherapeutic agents in clinical practice has revolutionized cancer treatment in the past decade, both in oncology and hematology. The transfer of the immunotherapeutic concepts to the treatment of acute myeloid leukemia (AML) is hampered by various characteristics of the disease, including non-leukemia-restricted target antigen expression profile, low endogenous immune responses, and intrinsic resistance mechanisms of the leukemic blasts against immune responses. However, considerable progress has been made in this field in the past few years. Within this manuscript, we review the recent developments and the current status of the five currently most prominent immunotherapeutic concepts: (1) antibody-drug conjugates, (2) T cell-recruiting antibody constructs, (3) chimeric antigen receptor (CAR) T cells, (4) checkpoint inhibitors, and (5) dendritic cell vaccination. We focus on the clinical data that has been published so far, both for newly diagnosed and refractory/relapsed AML, but omitting immunotherapeutic concepts in conjunction with hematopoietic stem cell transplantation. Besides, we have included important clinical trials that are currently running or have recently been completed but are still lacking full publication of their results. While each of the concepts has its particular merits and inherent problems, the field of immunotherapy of AML seems to have taken some significant steps forward. Results of currently running trials will reveal the direction of further development including approaches combining two or more of these concepts

Integrated In Silico Prediction of Minor Histocompatibility Antigen Peptides in HLA-Matched Allogeneic Stem Cell Transplantation for Acute Myeloid Leukemia

Abstract Background and Rationale: T-cell responses to minor histocompatibility antigens (mHA) are important drivers of the beneficial graft versus leukemia (GvL) effect and harmful graft versus host disease (GvHD) pathology following HLA-matched allogeneic stem cell transplantation (alloSCT). Despite their importance, Genome Wide Association Studies (GWAS) have failed to elicit a prognostic set of individual mHA associated with the clinically observed GvL and GvH effects of alloSCT [Sato-Otsubo et al. Blood 2015]. This is likely due to a lack of public mHA shared across the global set of donor/recipient pairs (DRPs). Even an optimally frequent single nucleotide polymorphism (SNP) would result in a recipient restricted genetic variant in only 24% of DRPs with a matched unrelated donor (MUD) or 17% of DRPs with a matched related donor (MRD) [Armistead et al. PLoS One 2011]. Moreover, even when DRPs do share a recipient restricted genetic variant, any resulting peptide would have to bind a MHC molecule within the recipient for presentation to T-cells. Methods: To evaluate the role of mHA in alloSCT without requiring public mHA, we developed a bioinformatics pipeline to predict mHA peptides based on SNP differences taking into account peptide/MHC binding estimated by netMHCpan [Nielson et al. Genome Med 2016] and expected GvL vs GvH tissue expression derived from mRNA sequencing data from acute myeloid leukemia (AML) and normal hematopoietic, hepatobiliary, skin, and gastrointestinal tract tissues. In order to understand the distribution of mHA in HLA-matched alloSCT drawn from a diverse pool of DRPs, we applied this analysis to putative DRPs drawn from healthy individuals who underwent whole-exome sequencing as part of the 1000 Genomes Project (n = 1,916) [1000 Genomes Project Consortium et al. Nature 2015]. To evaluate the association of mHA with AML relapse and GvHD incidence following alloSCT, we predicted mHA from SNP data using clinical information from an earlier study [Armistead et al. PLoS One 2011]. Results: To determine a baseline for the number of predicted mHA in an alloSCT, we considered every possible pair of samples in the 1000 Genomes data set as a theoretical alloSCT (n = 3,669,140). We determined each sample's HLA type using PHLAT [Bai et al. BMC Genomics 2014] and then performed mHA predictions for all theoretical transplants with a 10 out of 10 HLA match (n = 10). Within each ethnicity represented in the 1000 Genomes data, the degree of HLA matching was greater than that of all ethnicities pooled, with the lowest HLA diversity in the Finnish, Chinese, and Japanese populations. The number of predicted mHA binding MHC with Kd &lt; 500nM ranged from 6,217 to 13,545 in the 1000 Genomes theoretical HLA-matched DRPs, with mHA contained in genes selectively expressed in AML versus those selectively expressed in GvH target organs numbering 213 to 610 and 367 to 1,135, respectively. HLA-A*02:01 restricted mHA were predicted for 37 actual DRPs in the context of MUD alloSCT and 97 DRPs from MRD alloSCT [Armistead et al. PLoS One 2011]. There were significantly more predicted mHA in MUD transplants (Figure 1). Taking into account both predicted peptide/MHC binding and tissue expression, the number of predicted GvL mHA was significantly associated with remission and the aggregate number of predicted GvH mHA was significantly associated with grade 2-4 GvHD incidence in MUD transplants (Figure 2). Conclusions: Prediction of mHA based on whole-exome sequencing data is feasible and can be used to discover associations of mHA distribution features with clinical outcomes including AML remission and GvHD incidence. Future work in larger datasets will be required to validate these predicted associations and guide development of mHA-directed therapeutics. Disclosures Molldrem: Astellas Pharma: Patents &amp; Royalties. </jats:sec

Post-Hematopoietic Stem Cell Transplantation (HSCT) Outcomes in Patients With AML Transplanted Prior to Achieving Platelet Recovery

n/