Feasibility of a Novel Academic BCMA-CART (HBI0101) for the Treatment of Relapsed and Refractory AL Amyloidosis

PURPOSE

AL amyloidosis (AL) treatments are generally based on those employed for multiple myeloma. Anti-B-cell maturation antigen (BCMA) chimeric antigen receptor T (CART)-cell therapy, already approved for multiple myeloma, might be too toxic for patients with AL.

EXPERIMENTAL DESIGN

Here we describe the ex vivo applicability of a novel in-house, academic anti-BCMA CAR construct on AL primary cells, as well as the safety and efficacy in 4 patients with relapsed/refractory (RR) primary AL, treated in a phase I clinical trial (NCT04720313).

RESULTS

Three had MAYO stage IIIa cardiac involvement at enrollment. The treatment proved relatively safe, with a short and manageable grade 3 cytokine release syndrome evident in 2 patients and no neurotoxicity in any. Cardiac decompensations, observed in 2 patients, were also short and manageable. The overall hematologic response and complete response rates were observed in all patients with an organ response evident in all four. Within a median follow-up period of 5.2 (2.5-9.5) months, all 4 patients maintained their responses.

CONCLUSIONS

BCMA-CART cells provide a first proof-of-concept that this therapy is safe enough and highly efficacious for the treatment of patients with advanced, RR AL.

Multifunctional nanoprobe for real-time in vivo monitoring of T cell activation

Genetically engineered T cells are a powerful new modality for cancer immunotherapy. However, their clinical application for solid tumors is challenging, and crucial knowledge on cell functionality in vivo is lacking. Here, we fabricated a nanoprobe composed of dendrimers incorporating a calcium sensor and gold nanoparticles, for dual-modal monitoring of engineered T cells within a solid tumor. T cells engineered to express a melanoma-specific T-cell receptor and loaded with the nanoprobe were longitudinally monitored within melanoma xenografts in mice. Fluorescent imaging of the nanoprobe's calcium sensor revealed increased intra-tumoral activation of the T cells over time, up to 24 h. Computed tomography imaging of the nanoprobe's gold nanoparticles revealed the cells' intra-tumoral distribution pattern. Quantitative analysis revealed the intra-tumoral T cell quantities. Thus, this nanoprobe reveals intra-tumoral persistence, penetration and functional status of genetically engineered T cells, which can advance T cell-based immunotherapy and promote next-generation live cell imaging.

Preclinical evaluation and structural optimization of anti-BCMA CAR to target multiple myeloma

Chimeric antigen receptor (CAR) T-cell based immunotherapy has become a promising treatment mainly for hematological malignancies. Following the major success of CD19-targeted CAR, new potential targets for other malignancies are required. As such, B-cell maturation antigen (BCMA) is an attractive tumor-associated antigen to be targeted in multiple myeloma (MM). Herein, we aimed at assessing the function and optimal configuration of different BCMA-specific CAR, based on the same targeting moiety but with a different hinge and co-stimulatory domain. We compared their function to that of a previously characterized BCMA-CAR used in clinical trials. All constructs were expressed at high levels by primary human T cells and could trigger cytokine production and cytotoxicity upon co-culture with multiple myeloma targets. Nonetheless, critical differences were observed in off-target activation, exhaustion, and activation marker expression and in vivo anti-tumoral activity mediated by these different constructs. Interestingly, we noted that CD8-based hinge, combined with a 4-1BB intracellular domain, proved superior compared to IgG4-connecting regions, and/or a CD28-signaling moiety respectively. Overall, this study emphasizes the influence of CAR primary structure on its function and led to the identification of a highly efficient BCMA-specific CAR, namely H8BB, which displayed superior anti-tumoral activity both in vitro and long-term in vivo efficacy.

Adoptive T-cell Immunotherapy: Perfecting Self-Defenses

As an important part of the immune system, T lymphocytes exhibit undoubtedly an important role in targeting and eradicating cancer. However, despite these characteristics, their natural antitumor response may be insufficient. Numerous clinical trials in terminally ill cancer patients testing the design of novel and efficient immunotherapeutic approaches based on the adoptive transfer of autologous tumor-specific T lymphocytes have shown encouraging results. Moreover, this also led to the approval of engineered T-cell therapies in patients. Herein, we will expand on the development and the use of such strategies using tumor-infiltrating lymphocytes or genetically engineered T-cells. We will also comment on the requirements and potential hurdles encountered when elaborating and implementing such treatments as well as the exciting prospects for this kind of emerging personalized medicine therapy.

Noninvasive Tracking of Natural Killer Cells Using Gold Nanoparticles

Natural killer (NK)-cell-based immunotherapy is emerging as an attractive approach for cancer treatment. However, to facilitate and expedite clinical implementation, important questions must be answered regarding the in vivo functionality and trafficking patterns of the transferred cells. We have recently developed a noninvasive cell-tracking technique, based on gold nanoparticles (GNPs) as cell-labeling and contrast agents for whole-body computed tomography (CT) imaging. Herein, we report the implementation of this technique for longitudinal and quantitative tracking of NK cell kinetics, the migration and biodistribution in tumor-bearing mice. NK cells were successfully labeled with GNPs, without impairing their biological function, as assessed both in vitro, by cytokine release and cytotoxicity assays, and in vivo, using a xenograft model of human tumors. Using CT, we longitudinally tracked the migration of intravenously injected NK cells and observed an accumulation of effector cell clusters at the tumor site, up to 72 h. Fluorescence imaging of the cells over time correlated with ex vivo quantitative analysis of gold content in the tumor, validating the accuracy and reliability of our technique. Our cell-tracking approach thus offers a valuable tool for preclinical studies, as well as for clinical applications, to elucidate the fate of NK cells and promote the implementation of NK-cell-based immunotherapy.

Combined presentation and immunogenicity analysis reveals a recurrent RAS.Q61K neoantigen in melanoma

Neoantigens are now recognized drivers of the antitumor immune response. Recurrent neoantigens, shared among groups of patients, have thus become increasingly coveted therapeutic targets. Here, we report on the data-driven identification of a robustly presented, immunogenic neoantigen that is derived from the combination of HLA-A*01:01 and RAS.Q61K. Analysis of large patient cohorts indicated that this combination applies to 3% of patients with melanoma. Using HLA peptidomics, we were able to demonstrate robust endogenous presentation of the neoantigen in 10 tumor samples. We detected specific reactivity to the mutated peptide within tumor-infiltrating lymphocytes (TILs) from 2 unrelated patients, thus confirming its natural immunogenicity. We further investigated the neoantigen-specific clones and their T cell receptors (TCRs) via a combination of TCR sequencing, TCR overexpression, functional assays, and single-cell transcriptomics. Our analysis revealed a diverse repertoire of neoantigen-specific clones with both intra- and interpatient TCR similarities. Moreover, 1 dominant clone proved to cross-react with the highly prevalent RAS.Q61R variant. Transcriptome analysis revealed a high association of TCR clones with specific T cell phenotypes in response to cognate melanoma, with neoantigen-specific cells showing an activated and dysfunctional phenotype. Identification of recurrent neoantigens and their reactive TCRs can promote "off-the-shelf" precision immunotherapies, alleviating limitations of personalized treatments.

A novel role for an old target: CD45 for breast cancer immunotherapy

Breast cancer subtypes have not shown significant response to current immunomodulatory therapies. Although most subtypes are treatable, triple negative breast cancer (TNBC), an aggressive highly metastatic cancer, comprising 10-20% of breast cancers, remains an unmet medical need. New strategies are needed in order to overcome flaws in the responsiveness to current TNBC therapies. Our aims were: first, to determine the efficacy of a novel immunomodulatory peptide, C24D, on TNBC and second, to elucidate the molecular mechanism by which C24D induces immune-modulating tumor killing. Using mass spectrometry analysis, we identified CD45 as the C24D binding receptor. In vitro and in vivo TNBC models were used to assess the efficacy of C24D in reversing TNBC-induced immunosuppression and in triggering immune-modulated tumor cell killing. The CD45 signal transduction pathway was evaluated by western blot and FACS analyses. We revealed that addition of PBMCs from healthy female donors to TNBC cells results in a cascade of suppressive CD45 intracellular signals. On binding to CD45's extra-cellular domain on TNBC-suppressed leukocytes, the C24D peptide re-activates the Src family of tyrosine kinases, resulting in specific tumor immune response. In vitro, immune reactivation by C24D results in an increase of CD69+ T and CD69+ NK cells, triggering specific killing of TNBC cells. In vivo, C24D induced CD8+ and activated CD56+ tumor infiltrated cells, resulting in tumor apoptosis. Our results should renew interest in molecules targeting CD45, such as the C24D peptide, as a novel strategy for TNBC immunotherapy.

Out of the bitter came forth sweet: Activating CD28-dependent co-stimulation via PD-1 ligands

Programmed cell death 1 (PDCD1, best known as PD-1) is a central negative regulator of effector T cells that is involved in the etiology of chronic inflammatory conditions, viral diseases, and cancer. We have recently sought to improve T-cell functions by means of a novel chimeric co-stimulatory molecule that could divert the negative signals normally transmitted by PD-1 into positive ones. Human T cells transduced to express a fusion protein encompassing the extracellular domain of PD-1 and the intracellular portion of the co-stimulatory molecule CD28, which we named PD-1/28, exhibited an increase in cytokine secretion, the upregulation of activation markers, an improved proliferative potential and superior antineoplastic activity in xenograft models of human melanoma.

Downregulation of CD45 Signaling in COVID-19 Patients Is Reversed by C24D, a Novel CD45 Targeting Peptide

CD45, the predominant transmembrane tyrosine phosphatase in leukocytes, is required for the efficient induction of T cell receptor signaling and activation. We recently reported that the CD45-intracellular signals in peripheral blood mononuclear cells (PBMCs) of triple negative breast cancer (TNBC) patients are inhibited. We also reported that C24D, an immune modulating therapeutic peptide, binds to CD45 on immune-suppressed cells and resets the functionality of the immune system via the CD45 signaling pathway. Various studies have demonstrated that also viruses can interfere with the functions of CD45 and that patients with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are immune-suppressed. Given the similarity between the role of CD45 in viral immune suppression and our findings on TNBC, we hypothesized that the C24D peptide may have a similar "immune-resetting" effect on PBMCs from COVID-19 patients as it did on PBMCs from TNBC patients. We tested this hypothesis by comparing the CD45/TCR intracellular signaling in PBMCs from ten COVID-19 patients vs. PBMCs from ten healthy volunteers. Herein, we report our findings, demonstrating the immune reactivating effect of C24D via the phosphorylation of the tyrosine 505 and 394 in Lck, the tyrosine 493 in ZAP-70 and the tyrosine 172 in VAV-1 proteins in the CD45 signaling pathway. Despite the relatively small number of patients in this report, the results demonstrate that C24D rescued CD45 signaling. Given the central role played by CD45 in the immune system, we suggest CD45 as a potential therapeutic target.

A TIGIT-based chimeric co-stimulatory switch receptor improves T-cell anti-tumor function

Background

Tumors can employ different mechanisms to evade immune surveillance and function. Overexpression of co-inhibitory ligands that bind to checkpoint molecules on the surface of T-cells can greatly impair the function of latter. TIGIT (T cell immunoreceptor with Ig and ITIM domains) is such a co-inhibitory receptor expressed by T and NK cells which, upon binding to its ligand (e.g., CD155), can diminish cytokine production and effector function. Additionally, the absence of positive co-stimulation at the tumor site can further dampen T-cell response.

Methods

As T-cell genetic engineering has become clinically-relevant in the recent years, we devised herein a strategy aimed at enhancing T-cell anti-tumor function by diverting T-cell coinhibitory signals into positive ones using a chimeric costimulatory switch receptor (CSR) composed of the TIGIT exodomain fused to the signaling domain of CD28.

Results

After selecting an optimized TIGIT-28 CSR, we co-transduced it along with tumor-specific TCR or CAR into human T-cells. TIGIT-28-equipped T-cells exhibited enhanced cytokine secretion and upregulation of activation markers upon co-culture with tumor cells. TIGIT-28 enhancing capability was also demonstrated in an original in vitro model of T-cell of hypofunction induction upon repetitive antigen exposure. Finally, we tested the function of this molecule in the context of a xenograft model of established human melanoma tumors and showed that TIGIT-28-engineered human T-cells demonstrated superior anti-tumor function.

Conclusion

Overall, we propose that TIGIT-based CSR can substantially enhance T-cell function and thus contribute to the improvement of engineered T cell-based immunotherapy.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0721-y) contains supplementary material, which is available to authorized users.

Level of neo-epitope predecessor and mutation type determine T cell activation of MHC binding peptides

BACKGROUND

Targeting epitopes derived from neo-antigens (or "neo-epitopes") represents a promising immunotherapy approach with limited off-target effects. However, most peptides predicted using MHC binding prediction algorithms do not induce a CD8 + T cell response, and there is a crucial need to refine the predictions to readily identify the best antigens that could mediate T-cell responses. Such a response requires a high enough number of epitopes bound to the target MHC. This number is correlated with both the peptide-MHC binding affinity and the number of peptides reaching the ER. Beyond this, the response may be affected by the properties of the neo-epitope mutated residues.

METHODS

Herein, we analyzed several experimental datasets from cancer patients to elaborate better predictive algorithms for T-cell reactivity to neo-epitopes.

RESULTS

Indeed, potent classifiers for epitopes derived from neo-antigens in melanoma and other tumors can be developed based on biochemical properties of the mutated residue, the antigen expression level and the peptide processing stage. Among MHC binding peptides, the present classifiers can remove half of the peptides falsely predicted to activate T cells while maintaining the absolute majority of reactive peptides.

CONCLUSIONS

The classifier properties further highlight the contribution of the quantity of peptides reaching the ER and the mutation type to CD8 + T cell responses. These classifiers were then validated on neo-antigens obtained from other datasets, confirming the validity of our prediction. Algorithm Availability: http://peptibase.cs.biu.ac.il/Tcell_predictor/ or by request from the authors as a standalone code.

T-cells "à la CAR-T(e)" - Genetically engineering T-cell response against cancer

The last decade will be remembered as the dawn of the immunotherapy era during which we have witnessed the approval by regulatory agencies of genetically engineered CAR T-cells and of checkpoint inhibitors for cancer treatment. Understandably, T-lymphocytes represent the essential player in these approaches. These cells can mediate impressive tumor regression in terminally-ill cancer patients. Moreover, they are amenable to genetic engineering to improve their function and specificity. In the present review, we will give an overview of the most recent developments in the field of T-cell genetic engineering including TCR-gene transfer and CAR T-cells strategies. We will also elaborate on the development of other types of genetic modifications to enhance their anti-tumor immune response such as the use of co-stimulatory chimeric receptors (CCRs) and unconventional CARs built on non-antibody molecules. Finally, we will discuss recent advances in genome editing and synthetic biology applied to T-cell engineering and comment on the next challenges ahead.

Increased RNA Editing May Provide a Source for Autoantigens in Systemic Lupus Erythematosus

RNA-editing mechanisms, which induce nucleotide substitution in the RNA, increase transcript and protein diversities. Editing dysregulation has been shown to lead to grave outcomes, and transcriptome-wide aberrant RNA editing has been found in tumors. However, little is known about the involvement of editing in other diseases. Systemic lupus erythematosus (SLE) is a multisystemic autoimmune disease characterized by a loss of tolerance for autoantigens from various tissues and the production of multiple autoantibodies. Here, we show that blood samples from individuals with SLE have abnormally high levels of RNA editing, some of which affect proteins and potentially generate novel autoantigens. We suggest that elevated RNA editing, either by ADARs or APOBECs, may be involved in the pathophysiology of SLE, as well as in other autoimmune diseases, by generating or increasing the autoantigen load, a key requisite for the progression of autoimmunity.

Fast Image-Guided Stratification Using Anti-Programmed Death Ligand 1 Gold Nanoparticles for Cancer Immunotherapy

Cancer immunotherapy has made enormous progress in offering safer and more effective treatments for the disease. Specifically, programmed death ligand 1 antibody (αPDL1), designed to perform immune checkpoint blockade (ICB), is now considered a pillar in cancer immunotherapy. However, due to the complexity and heterogeneity of tumors, as well as the diversity in patient response, ICB therapy only has a 30% success rate, at most; moreover, the efficacy of ICB can be evaluated only two months after start of treatment. Therefore, early identification of potential responders and nonresponders to therapy, using noninvasive means, is crucial for improving treatment decisions. Here, we report a straightforward approach for fast, image-guided prediction of therapeutic response to ICB. In a colon cancer mouse model, we demonstrate that the combination of computed tomography imaging and gold nanoparticles conjugated to αPDL1 allowed prediction of therapeutic response, as early as 48 h after treatment. This was achieved by noninvasive measurement of nanoparticle accumulation levels within the tumors. Moreover, we show that the nanoparticles efficiently prevented tumor growth with only a fifth of the standard dosage of clinical care. This technology may be developed into a powerful tool for early and noninvasive patient stratification as responders or nonresponders.

A novel lncRNA, GASL1, inhibits cell proliferation and restricts E2F1 activity

The human genome encodes thousands of unique long non-coding RNAs (lncRNAs), many of which are emerging as critical regulators of cell fate. However, their functions as well as their transcriptional regulation are only partially understood. The E2F1 transcription factor induces both proliferation and apoptosis, and is a critical downstream target of the tumor suppressor, RB. Here, we provide evidence that a novel lncRNA named GASL1 is transcriptionally regulated by E2F1; GASL1 levels are elevated upon activation of exogenous E2F1 or endogenous E2Fs. Inhibition of GASL1 expression induced cell cycle progression, and in particular, G1 exit. Moreover, GASL1 silencing enhanced cell proliferation, while, conversely, its ectopic expression inhibited proliferation. Knockdown of GASL1 also enhanced E2F1-induced apoptosis, suggesting the existence of an E2F/GASL1 negative feedback loop. In agreement with this notion, silencing of GASL1 led to increased levels of phosphorylated pRB and loss of Rb impaired the effect of GASL1 silencing on G1 exit. Importantly, xenograft experiments demonstrated that GASL1 deletion enhances tumor growth. Moreover, low levels of GASL1 are associated with decreased survival of liver cancer patients. Taken together, our data identify GASL1 as a novel lncRNA regulator of cell cycle progression and cell proliferation with a potential role in cancer.

Targeting Multiple Tumors Using T-Cells Engineered to Express a Natural Cytotoxicity Receptor 2-Based Chimeric Receptor

Recent developments in cancer treatment are demonstrating the increasing and powerful potential of immunotherapeutic strategies. In this regard, the adoptive transfer of tumor-specific T-lymphocytes approaches can lead to tumor regression in cancer patients. More recently, the use of T-cells genetically engineered to express cancer-specific receptors such as the anti-CD19 chimeric antigen receptor (CAR) continues to show promise for the treatment of hematological malignancies. Still, there is a crucial need to develop efficient CAR-T cell approaches for the treatment of solid tumors. It has been shown that other lymphocytes such as natural killer (NK) cells can demonstrate potent antitumor function—nonetheless, their use in immunotherapy is rather limited due to difficulties in expanding these cells to therapeutically relevant numbers and to suppression by endogenous inhibitory mechanisms. Cancer recognition by NK cells is partly mediated by molecules termed natural cytotoxicity receptors (NCRs). In the present study, we hypothesize that it is possible to endow T-cells with an NK recognition pattern, providing them with a mean to recognize tumor cells, in a non-MHC restricted way. To test this, we genetically modified human T-cells with different chimeric receptors based on the human NCR2 molecule and then assessed their antitumor activity in vitro and in vivo. Our results show that expression in primary lymphocytes of an NCR2-derived CAR, termed s4428z, confers T-cells with the ability to specifically recognize heterogeneous tumors and to mediate tumor cytotoxicity in a mouse model. This study demonstrates the benefit of combining tumor recognition capability of NK cells with T cell effectiveness to improve cancer immunotherapy.

The mutational status of p53 can influence its recognition by human T-cells

p53 was reported to be an attractive immunotherapy target because it is mutated in approximately half of human cancers, resulting in its inactivation and often accumulation in tumor cells. Peptides derived from p53 are presented by class I MHC molecules and may act as tumor-associated epitopes which could be targeted by p53-specific T cells. Interestingly, it was recently shown that there is a lack of significant correlation between p53 expression levels in tumors and their recognition by p53-TCR transduced T cells. To better understand the influence of the mutational status of p53 on its presentation by the MHC system and on T cell antitumor reactivity, we generated several mutant p53 constructs and expressed them in HLA-A2+/p53- cells. Upon co-culture with p53-specific T cells, we measured the specific recognition of p53-expressing target cells by means of cytokine secretion, marker upregulation and cytotoxicity, and in parallel determined p53 expression levels by intracellular staining. We also examined the relevance of antigen presentation components on p53 recognition and the impact of mutant p53 expression on cell-cycle dynamics. Our results show that selected p53 mutations altering protein stability can modulate p53 presentation to T cells, leading to a differential immune reactivity inversely correlated with measured p53 protein levels. Thus, p53 may behave differently than other classical tumor antigens and its mutational status should therefore be taken into account when elaborating immunotherapy treatments of cancer patients targeting p53.

MHC-multimer guided isolation of neoepitopes specific T cells as a potent-personalized cancer treatment strategy

Analysis of genomic data from patient tumors provides valuable information as to potential T-cell targets such as neoepitopes. We developed an approach to characterize, isolate and utilize neoantigens-specific T cells using MHC/peptide tetramers from fresh tumor digests and peripheral blood. This bears important implications for the implementation of T cell-based immunotherapy.

Durable Complete Response from Metastatic Melanoma after Transfer of Autologous T Cells Recognizing 10 Mutated Tumor Antigens

Immunotherapy treatment of patients with metastatic cancer has assumed a prominent role in the clinic. Durable complete response rates of 20% to 25% are achieved in patients with metastatic melanoma following adoptive cell transfer of T cells derived from metastatic lesions, responses that appear in some patients to be mediated by T cells that predominantly recognize mutated antigens. Here, we provide a detailed analysis of the reactivity of T cells administered to a patient with metastatic melanoma who exhibited a complete response for over 3 years after treatment. Over 4,000 nonsynonymous somatic mutations were identified by whole-exome sequence analysis of the patient's autologous normal and tumor cell DNA. Autologous B cells transfected with 720 mutated minigenes corresponding to the most highly expressed tumor cell transcripts were then analyzed for their ability to stimulate the administered T cells. Autologous tumor-infiltrating lymphocytes recognized 10 distinct mutated gene products, but not the corresponding wild-type products, each of which was recognized in the context of one of three different MHC class I restriction elements expressed by the patient. Detailed clonal analysis revealed that 9 of the top 20 most prevalent clones present in the infused T cells, comprising approximately 24% of the total cells, recognized mutated antigens. Thus, we have identified and enriched mutation-reactive T cells and suggest that such analyses may lead to the development of more effective therapies for the treatment of patients with metastatic cancer. Cancer Immunol Res; 4(8); 669-78. ©2016 AACR.

Stable, Nonviral Expression of Mutated Tumor Neoantigen-specific T-cell Receptors Using the Sleeping Beauty Transposon/Transposase System

Neoantigens unique to each patient's tumor can be recognized by autologous T cells through their T-cell receptor (TCR) but the low frequency and/or terminal differentiation of mutation-specific T cells in tumors can limit their utility as adoptive T-cell therapies. Transfer of TCR genes into younger T cells from peripheral blood with a high proliferative potential could obviate this problem. We generated a rapid, cost-effective strategy to genetically engineer cancer patient T cells with TCRs using the clinical Sleeping Beauty transposon/transposase system. Patient-specific TCRs reactive against HLA-A*0201-restriced neoantigens AHNAK(S2580F) or ERBB2(H473Y) or the HLA-DQB*0601-restricted neoantigen ERBB2IP(E805G) were assembled with murine constant chains and cloned into Sleeping Beauty transposons. Patient peripheral blood lymphocytes were coelectroporated with SB11 transposase and Sleeping Beauty transposon, and transposed T cells were enriched by sorting on murine TCRβ (mTCRβ) expression. Rapid expansion of mTCRβ(+) T cells with irradiated allogeneic peripheral blood lymphocytes feeders, OKT3, interleukin-2 (IL-2), IL-15, and IL-21 resulted in a preponderance of effector (CD27(-)CD45RA(-)) and less-differentiated (CD27(+)CD45RA(+)) T cells. Transposed T cells specifically mounted a polyfunctional response against cognate mutated neoantigens and tumor cell lines. Thus, Sleeping Beauty transposition of mutation-specific TCRs can facilitate the use of personalized T-cell therapy targeting unique neoantigens.

Engineering T-Cell Specificity Genetically to Generate Anti-melanoma Reactivity

Melanoma tumors are known to harbor a high number of mutations leading to the expression of neo-antigens which can be recognized by the patient adaptive immune system. In this regard, immunotherapies involving adoptive cell transfer (ACT) of tumor-specific T-cells constitute a promising approach to treat melanoma. However, these cells do not always preexist in the patient or are difficult to isolate and/or expand. Thus, as the specificity of T-lymphocytes is determined by their T-cell receptor (TCR), it is possible to convert peripheral T-cells into cancer specific lymphocytes by transducing them to express a receptor that recognizes a defined tumor epitope. To this end, retroviral vectors can be used to efficiently transduce actively dividing cells such as proliferating T cells, while being relatively safe to the user. As we show herein, this approach is powerful and can be easily implemented, paving the way to the development of advanced research tools and potent clinical immunotherapeutic strategies.

Isolation of neoantigen-specific T cells from tumor and peripheral lymphocytes

Adoptively transferred tumor-infiltrating T lymphocytes (TILs) that mediate complete regression of metastatic melanoma have been shown to recognize mutated epitopes expressed by autologous tumors. Here, in an attempt to develop a strategy for facilitating the isolation, expansion, and study of mutated antigen-specific T cells, we performed whole-exome sequencing on matched tumor and normal DNA isolated from 8 patients with metastatic melanoma. Candidate mutated epitopes were identified using a peptide-MHC-binding algorithm, and these epitopes were synthesized and used to generate panels of MHC tetramers that were evaluated for binding to tumor digests and cultured TILs used for the treatment of patients. This strategy resulted in the identification of 9 mutated epitopes from 5 of the 8 patients tested. Cells reactive with 8 of the 9 epitopes could be isolated from autologous peripheral blood, where they were detected at frequencies that were estimated to range between 0.4% and 0.002%. To the best of our knowledge, this represents the first demonstration of the successful isolation of mutation-reactive T cells from patients' peripheral blood prior to immune therapy, potentially providing the basis for designing personalized immunotherapies to treat patients with advanced cancer.

Nanomedicine for Cancer Immunotherapy: Tracking Cancer-Specific T-Cells in Vivo with Gold Nanoparticles and CT Imaging

Application of immune cell-based therapy in routine clinical practice is challenging due to the poorly understood mechanisms underlying success or failure of treatment. Development of accurate and quantitative imaging techniques for noninvasive cell tracking can provide essential knowledge for elucidating these mechanisms. We designed a novel method for longitudinal and quantitative in vivo cell tracking, based on the superior visualization abilities of classical X-ray computed tomography (CT), combined with state-of-the-art nanotechnology. Herein, T-cells were transduced to express a melanoma-specific T-cell receptor and then labeled with gold nanoparticles (GNPs) as a CT contrast agent. The GNP-labeled T-cells were injected intravenously to mice bearing human melanoma xenografts, and whole-body CT imaging allowed examination of the distribution, migration, and kinetics of T-cells. Using CT, we found that transduced T-cells accumulated at the tumor site, as opposed to nontransduced cells. Labeling with gold nanoparticles did not affect T-cell function, as demonstrated both in vitro, by cytokine release and proliferation assays, and in vivo, as tumor regression was observed. Moreover, to validate the accuracy and reliability of the proposed cell tracking technique, T-cells were labeled both with green fluorescent protein for fluorescence imaging, and with GNPs for CT imaging. A remarkable correlation in signal intensity at the tumor site was observed between the two imaging modalities, at all time points examined, providing evidence for the accuracy of our CT cell tracking abilities. This new method for cell tracking with CT offers a valuable tool for research, and more importantly for clinical applications, to study the fate of immune cells in cancer immunotherapy.

Enhanced antitumor activity mediated by human 4-1BB-engineered T cells

4-1BB (CD137) is a costimulatory molecule transiently expressed on the T-cell surface after TCR engagement, whereas its ligand 4-1BBL can be found on professional antigen-presenting cells, but more importantly, also on tumor cells. As the role of the 4-1BB/4-1BBL pathway has emerged central to CD8(+) T-cell responses and survival, we sought to test its relevance in the context of genetically modified human T cells. To that end, T cells purified from healthy donors and from vaccinated-melanoma patients were transduced to express high levels of constitutive 4-1BB. 4-1BB-transduced T cells were cocultured with melanoma tumor lines and exhibited enhanced cytokine secretion, upregulation of activation markers as well as increased cytotoxicity in a chick-chorioallantoic membrane model of human melanoma tumors. In addition, these cells expanded and proliferated at a higher rate, expressed heightened levels of the antiapoptotic molecule Bcl(XL) and were also relatively insensitive to immunosuppression mediated by transforming growth factor-β, compared to control cells. We also show that 4-1BBL expression on the target cell is essential to 4-1BB-mediated functional improvement. Overall, we conclude that the modification of human T cells with 4-1BB yields enhanced antitumor function which may have important applications in therapies based on the genetic modification of patient lymphocytes.

CXCR1 as a novel target for directing reactive T cells toward melanoma: implications for adoptive cell transfer immunotherapy

Adoptive cell transfer therapy with reactive T cells is one of the most promising immunotherapeutic modalities for metastatic melanoma patients. Homing of the transferred T cells to all tumor sites in sufficient numbers is of great importance. Here, we seek to exploit endogenous chemotactic signals in order to manipulate and enhance the directional trafficking of transferred T cells toward melanoma. Chemokine profiling of 15 melanoma cultures shows that CXCL1 and CXCL8 are abundantly expressed and secreted from melanoma cultures. However, the complimentary analysis on 40 melanoma patient-derived tumor-infiltrating lymphocytes (TIL) proves that the corresponding chemokine receptors are either not expressed (CXCR2) or expressed at low levels (CXCR1). Using the in vitro transwell system, we demonstrate that TIL cells preferentially migrate toward melanoma and that endogenously expressing CXCR1 TIL cells are significantly enriched among the migrating lymphocytes. The role of the chemokines CXCL1 and CXCL8 is demonstrated by partial abrogation of this enrichment with anti-CXCL1 and anti-CXCL8 neutralizing antibodies. The role of the chemokine receptor CXCR1 is validated by the enhanced migration of CXCR1-engineered TIL cells toward melanoma or recombinant CXCL8. Cytotoxicity and IFNγ secretion activity are unaltered by CXCR1 expression profile. Taken together, these results mark CXCR1 as a candidate for genetic manipulations to enhance trafficking of adoptively transferred T cells. This approach is complimentary and potentially synergistic with other genetic strategies designed to enhance anti-tumor potency.

How (specific) would like your T-cells today? Generating T-cell therapeutic function through TCR-gene transfer

T-cells are central players in the immune response against both pathogens and cancer. Their specificity is solely dictated by the T-cell receptor (TCR) they clonally express. As such, the genetic modification of T lymphocytes using pathogen- or cancer-specific TCRs represents an appealing strategy to generate a desired immune response from peripheral blood lymphocytes. Moreover, notable objective clinical responses were observed in terminally ill cancer patients treated with TCR-gene modified cells in several clinical trials conducted recently. Nevertheless, several key aspects of this approach are the object of intensive research aimed at improving the reliability and efficacy of this strategy. Herein, we will survey recent studies in the field of TCR-gene transfer dealing with the improvement of this approach and its application for the treatment of malignant, autoimmune, and infectious diseases.

Incorporation of transmembrane hydrophobic mutations in the TCR enhance its surface expression and T cell functional avidity

TCR-gene transfer represents an effective way to redirect the specificity of T lymphocytes for therapeutic purposes. Recent successful clinical trials have underscored the potential of this approach in which efficient expression of the exogenous TCR has been directly linked to the efficacy of T cell activity. It has been also demonstrated that the TCR exhibits a lack of stability associated with the presence of positively charged residues in its transmembrane (TM) region. In this study, we designed an original approach selectively to improve exogenous TCR stability by increasing the hydrophobic nature of the TCRα TM region. Incorporation of hydrophobic residues at evolutionarily permissive positions resulted in an enhanced surface expression of the TCR chains, leading to an improved cellular avidity and anti-tumor TCR activity. Furthermore, this strategy was successfully applied to different TCRs, enabling the targeting of human tumors from different histologies. We also show that the combination of these hydrophobic mutations with another TCR-enhancing approach further improved TCR expression and function. Overall, these findings provide information regarding TCR TM composition that can be applied for the improvement of TCR-gene transfer-based treatments.

Human γδ T lymphocytes are licensed for professional antigen presentation by interaction with opsonized target cells

Activated human blood γδ T cells have also been previously demonstrated to behave as professional APCs, although the processes that control APC function have not been characterized. n this study, we show that the acquisition of potent APC function by human blood γδ T cells is achieved after physical interaction with an Ab-coated target cell, a process that we refer to as licensing. In cancer models, licensing of γδ T cells by tumor-reactive mAbs promotes the uptake of tumor Ags and professional presentation to tumor-reactive αβ T cells. We propose that licensing by Ab is a mechanism whereby the adaptive properties of γδ T cells are induced by their innate functions in a spatially and temporally controlled manner.

Evidence of genetic association between TNFRSF1A encoding the p55 tumour necrosis factor receptor, and ankylosing spondylitis in UK Caucasians

OBJECTIVES

To replicate the possible genetic association between ankylosing spondylitis (AS) and TNFRSF1A.

METHODS

TNFRSF1A was re-sequenced in 48 individuals with AS to identify novel polymorphisms. Nine single nucleotide polymorphisms (SNPs) in TNFRSF1A and 5 SNPs in the neighbouring gene SCNN1A were genotyped in 1604 UK Caucasian individuals with AS and 1019 matched controls. An extended study was implemented using additional genotype data on 8 of these SNPs from 1400 historical controls from the 1958 British Birth Cohort. A meta-analysis of previously published results was also undertaken.

RESULTS

One novel variant in intron 6 was identified but no new coding variants. No definite associations were seen in the initial study but in the extended study there were weak associations with rs4149576 (p=0.04) and rs4149577 (p=0.007). In the meta-analysis consistent, somewhat stronger associations were seen with rs4149577 (p=0.002) and rs4149578 (p=0.006).

CONCLUSIONS

These studies confirm the weak genetic associations between AS and TNFRSF1A. In view of the previously reported associations of TNFRSF1A with AS, in Caucasians and Chinese, and the biological plausibility of this candidate gene, replication of this finding in well powered studies is clearly indicated.

Genetically modulating T-cell function to target cancer

The adoptive transfer of tumor-specific T-lymphocytes holds promise for the treatment of metastatic cancer. Genetic modulation of T-lymphocytes using TCR transfer with tumor-specific TCR genes is an attractive strategy to generate anti-tumor response, especially against large solid tumors. Recently, several clinical trials have demonstrated the therapeutic potential of this approach which lead to impressive tumor regression in cancer patients. Still, several factors may hinder the clinical benefit of this approach, such as the type of cells to modulate, the vector configuration or the safety of the procedure. In the present review we will aim at giving an overview of the recent developments related to the immune modulation of the anti-tumor adaptive response using genetically engineered lymphocytes and will also elaborate the development of other genetic modifications to enhance their anti-tumor immune response.

Enhanced receptor expression and in vitro effector function of a murine-human hybrid MART-1-reactive T cell receptor following a rapid expansion

Peripheral blood lymphocytes (PBL) genetically modified to express T cell receptors (TCR) specific to known melanoma antigens, such as melanoma antigen recognized by T cells-1 (MART-1), and gp100 can elicit objective tumor regression when administered to patients with metastatic melanoma. It has also been demonstrated that modifications within the constant regions of a fully human TCR can enhance surface expression and stability without altering antigen specificity. In this study, we evaluated the substitution of murine constant regions for their human counterpart within the DMF5 MART-1-specific TCR. Unlike previous studies, all modified TCRs were inserted into retroviral vectors and analyzed for expression and function following a clinical transduction protocol. PBL were transduced with retroviral supernatant generated from stable packaging lines encoding melanoma-specific TCRs. This protocol resulted in high levels of antigen-specific T cells without the need for additional peptide stimulation and selection. Both the human and murinized TCR efficiently transduced PBL; however, the murinized TCR exhibited significantly higher tetramer binding, mean fluorescence intensity, as well as, increased in vitro effector function following our clinical transduction and expansion protocol. Additional TCR modifications including insertion of a second disulfide bond or the linker modifications evaluated herein did not significantly enhance TCR expression or subsequent in vitro effector function. We conclude that the substitution of a human constant region with a murine constant region was sufficient to increase receptor expression and tetramer binding as well as antitumor activity of the DMF5 TCR and could be a tool to augment other antigen-specific TCR.

Potential mechanisms of endogenous retroviral-mediated genomic instability in human cancer

Malignancy results from a complex combination of genetic and epigenetic changes, the full effects of which are still largely unknown. Here we summarize current knowledge of the origin, retrotranspositional activity, epigenetic state, and transcription of human endogenous retroviruses (HERVs), and then discuss the potential effects of their deregulation in cancer. Evidence suggests that cancer-associated epigenetic changes most likely underlie potential HERV-mediated effects on genome and transcriptome instability and may play a role in malignancy. Despite our currently limited understanding of the importance of HERVs or other transposable elements in cancer development, we believe that the emerging era of high-throughput sequencing of cancer genomes, epigenomes, and transcriptomes will provide unprecedented opportunities to investigate these roles in the future.

Relationship of p53 overexpression on cancers and recognition by anti-p53 T cell receptor-transduced T cells

Tumor suppressor p53 is reported to be an attractive immunotherapy target because it is mutated in approximately half of human cancers, resulting in inactivation and often an accumulation of the protein in the tumor cells. Only low amounts of protein are detectable in normal tissues. The differential display of antigen in normal versus tumor tissues has been reported to create an opportunity to target p53 by immunotherapy. We sought to determine the relationship between p53 expression and its recognition by cognate T cells in human tumors including common epithelial malignancies. Inasmuch as nonsense or missense p53 mutations may disrupt processing and presentation, we studied tumors with either identified wild-type or mutated p53, based on our gene-sequencing studies or published data. T cells transduced with a high-affinity, p53(264-272)-reactive T cell receptor (TCR) derived from HLA-A2.1 transgenic mice recognized a wide panel of human tumor lines. There was no significant correlation between p53 expression in tumors and recognition by the anti-p53 TCR-transduced T cells. This conclusion was based on the study of 48 cell lines and is in contrast to several prior studies that used only a limited number of selected cell lines. A panel of normal cells was evaluated for recognition, and some of these populations were capable of stimulating anti-p53 T cells, albeit at low levels. These studies raise doubts concerning the suitability of targeting p53 in the immunotherapy of cancer patients.

Lentiviral vector design for optimal T cell receptor gene expression in the transduction of peripheral blood lymphocytes and tumor-infiltrating lymphocytes

Lentiviral vectors containing promoters of distinct origins, that is, strong viral promoters (cytomegalovirus [CMV] and murine stem cell virus [MSCV]), a cellular promoter (phosphoglycerate kinase [PGK]), and two composite promoters (CAG [a composite promoter sequence comprised of the CMV enhancer and portions of the chicken beta-actin promoter and the rabbit beta-globin gene] and SV40/CD43), were used to evaluate green fluorescent protein (GFP) reporter gene expression in human primary peripheral blood lymphocytes (PBLs) and tumor-infiltrating lymphocytes (TILs). In PBLs, vectors containing the MSCV promoter were found to be optimal for expression in both minimally stimulated and highly activated lymphocytes. The stability of gene expression was monitored for up to 7 weeks in culture and the MSCV promoter-containing vector was found to be comparable to the cellular PGK promoter-containing vector. The MSCV promoter-containing lentiviral vector was also the most active in transduced TILs and these cells retained biological activity as measured by antimelanoma antigen reactivity. Using the knowledge gained in comparing individual promoters, a series of two-gene-containing lentiviral vectors was constructed in an attempt to produce the alpha and beta chains of antitumor antigen T cell receptors (TCRs). Dual-promoter or internal ribosome entry site (IRES)-containing vector designs were evaluated and found to be unable to produce both chains of the TCR in amounts that led to significant biological activity. In contrast, if the alpha and beta chains were linked by a 2A ribosomal skip peptide, both proper TCR chain pairing and biologically activity were observed. This paper emphasizes the need to optimize both promoter function and protein synthesis in constructs that require stoichiometric production of multiple protein subunits.

Efficient nonviral Sleeping Beauty transposon-based TCR gene transfer to peripheral blood lymphocytes confers antigen-specific antitumor reactivity

Genetically engineered lymphocytes hold promise for the treatment of genetic disease, viral infections and cancer. However, current methods for genetic transduction of peripheral blood lymphocytes rely on viral vectors, which are hindered by production and safety-related problems. In this study, we demonstrated an efficient novel nonviral platform for gene transfer to lymphocytes. The Sleeping Beauty transposon-mediated approach allowed for long-term stable expression of transgenes at approximately 50% efficiency. Utilizing transposon constructs expressing tumor antigen-specific T-cell receptor genes targeting p53 and MART-1, we demonstrated sustained expression and functional reactivity of transposon-engineered lymphocytes on encountering target antigen presented on tumor cells. We found that transposon- and retroviral-modified lymphocytes had comparable transgene expression and phenotypic function. These results demonstrate the promise of nonviral ex vivo genetic modification of autologous lymphocytes for the treatment of cancer and immunologic disease.

Risk for opportunistic disease and death after reinitiating continuous antiretroviral therapy in patients with HIV previously receiving episodic therapy: a randomized trial

BACKGROUND

Episodic use of antiretroviral therapy guided by CD4+ cell counts is inferior to continuous antiretroviral therapy.

OBJECTIVE

To determine whether reinitiating continuous antiretroviral therapy in patients who received episodic treatment reduces excess risk for opportunistic disease or death.

DESIGN

Randomized, controlled trial.

SETTING

Sites in 33 countries.

PATIENTS

5472 HIV-infected individuals with CD4(+) cell counts greater than 0.350 x 10(9) cells/L enrolled from January 2002 to January 2006.

INTERVENTION

Episodic or continuous antiretroviral therapy initially, followed by continuous therapy in participants previously assigned to episodic treatment.

MEASUREMENTS

Opportunistic disease or death was the primary outcome.

RESULTS

Eighteen months after the recommendation to reinitiate continuous therapy, mean CD4+ cell counts were 0.152 x 10(9) cells/L (95% CI, 0.136 to 0.167 x 10(9) cells/L) less in participants previously assigned to episodic treatment (P < 0.001). The proportion of follow-up time spent with CD4+ cell counts of 0.500 x 10(9) cells/L or more and HIV RNA levels of 400 copies/mL or less was 29% for participants initially assigned to episodic therapy and 66% for those assigned to continuous therapy. Participants who reinitiated continuous therapy experienced rapid suppression of HIV RNA levels (89.7% with HIV RNA levels < or =400 copies/mL after 6 months), but CD4+ cell counts after 6 months remained 0.140 x 10(9) cells/L below baseline. The hazard ratio (episodic versus continuous treatment) for opportunistic disease or death decreased after the recommendation to reinitiate continuous therapy (from 2.5 [CI, 1.8 to 3.5] to 1.4 [CI, 1.0 to 2.0]; P = 0.033 for difference). The residual excess risk was attributable to failure to reinitiate therapy by some participants and slow recovery of CD4+ cell counts for those who reinitiated therapy.

LIMITATION

Follow-up was too short to assess the full effect of switching from episodic to continuous antiretroviral therapy.

CONCLUSION

Reinitiating continuous antiretroviral therapy in patients previously assigned to episodic treatment reduced excess risk for opportunistic disease or death, but excess risk remained. Episodic antiretroviral therapy, as used in the SMART study, should be avoided.

Enhanced antitumor activity of murine-human hybrid T-cell receptor (TCR) in human lymphocytes is associated with improved pairing and TCR/CD3 stability

Little is known about the biology of murine T-cell receptors (TCR) expressed in human cells. We recently observed that a murine anti-human p53 TCR is highly functional when expressed in human lymphocytes. Herein, we compare human and mouse TCR function and expression to delineate the molecular basis for the apparent superior biological activity of murine receptors in human T lymphocytes. To this end, we created hybrid TCRs where we swapped the original constant regions with either human or mouse ones, respectively. We showed that murine or "murinized" receptors were overexpressed on the surface of human lymphocytes compared with their human/humanized counterparts and were able to mediate higher levels of cytokine secretion when cocultured with peptide-pulsed antigen-presenting cells. Preferential pairing of murine constant regions and improved CD3 stability seemed to be responsible for these observations. These enhanced biological properties translated into significantly greater antitumor response mediated by TCR with mouse constant regions. Furthermore, we were able to circumvent the natural low avidity of class I MHC TCR in CD4(+) cells by introducing the murinized TCR into CD4(+) lymphocytes, giving them the ability to recognize melanoma tumors. These findings have implications for human TCR gene transfer therapy and may provide new insights into the biology of the TCR/CD3 complex.

Enhanced antitumor activity of T cells engineered to express T-cell receptors with a second disulfide bond

Adoptive transfer of genetically T-cell receptor (TCR)-modified lymphocytes has been recently reported to cause objective cancer regression. However, a major limitation to this approach is the mispairing of the introduced chains with the endogenous TCR subunits, which leads to reduced TCR surface expression and, subsequently, to their lower biological activity. We here show that it is possible to improve TCR gene transfer by adding a single cysteine on each receptor chain to promote the formation of an additional interchain disulfide bond. We show that cysteine-modified receptors were more highly expressed on the surface of human lymphocytes compared with their wild-type counterparts and able to mediate higher levels of cytokine secretion and specific lysis when cocultured with specific tumor cell lines. Furthermore, cysteine-modified receptors retained their enhanced function in CD4(+) lymphocytes. We also show that this approach can be employed to enhance the function of humanized and native murine receptors in human cells. Preferential pairing of cysteine-modified receptor chains accounts for these observations, which could have significant implications for the improvement of TCR gene therapy.

Extrathymic generation of tumor-specific T cells from genetically engineered human hematopoietic stem cells via Notch signaling

Adoptive cell transfer (ACT) of tumor-reactive lymphocytes has been shown to be an effective treatment for cancer patients. Studies in murine models of ACT indicated that antitumor efficacy of adoptively transferred T cells is dependent on the differentiation status of the cells, with lymphocyte differentiation inversely correlated with in vivo antitumor effectiveness. T-cell in vitro development technologies provide a new opportunity to generate naive T cells for the purpose of ACT. In this study, we genetically modified human umbilical cord blood-derived hematopoietic stem cells (HSCs) to express tumor antigen-specific T-cell receptor (TCR) genes and generated T lymphocytes by coculture with a murine cell line expressing Notch-1 ligand, Delta-like-1 (OP9-DL1). Input HSCs were differentiated into T cells as evidenced by the expression of T-cell markers, such as CD7, CD1a, CD4, CD8, and CD3, and by detection of TCR excision circles. We found that such in vitro differentiated T cells expressed the TCR and showed HLA-A2-restricted, specific recognition and killing of tumor antigen peptide-pulsed antigen-presenting cells but manifested additional natural killer cell-like killing of tumor cell lines. The genetic manipulation of HSCs has broad implications for ACT of cancer.

Cytokine-independent growth and clonal expansion of a primary human CD8+ T-cell clone following retroviral transduction with the IL-15 gene

Malignancies arising from retrovirally transduced hematopoietic stem cells have been reported in animal models and human gene therapy trials. Whether mature lymphocytes are susceptible to insertional mutagenesis is unknown. We have characterized a primary human CD8(+) T-cell clone, which exhibited logarithmic ex vivo growth in the absence of exogenous cytokine support for more than 1 year after transduction with a murine leukemia virus-based vector encoding the T-cell growth factor IL-15. Phenotypically, the clone was CD28(-), CD45RA(-), CD45RO(+), and CD62L(-), a profile consistent with effector memory T lymphocytes. After gene transfer with tumor-antigen-specific T-cell receptors, the clone secreted IFN-gamma upon encountering tumor targets, providing further evidence that they derived from mature lymphocytes. Gene-expression analyses revealed no evidence of insertional activation of genes flanking the retroviral insertion sites. The clone exhibited constitutive telomerase activity, and the presence of autocrine loop was suggested by impaired cell proliferation following knockdown of IL-15R alpha expression. The generation of this cell line suggests that nonphysiologic expression of IL-15 can result in the long-term in vitro growth of mature human T lymphocytes. The cytokine-independent growth of this line was a rare event that has not been observed in other IL-15 vector transduction experiments or with any other integrating vector system. It does not appear that the retroviral vector integration sites played a role in the continuous growth of this cell clone, but this remains under investigation.

Gene transfer of tumor-reactive TCR confers both high avidity and tumor reactivity to nonreactive peripheral blood mononuclear cells and tumor-infiltrating lymphocytes

Cell-based antitumor immunity is driven by CD8(+) cytotoxic T cells bearing TCR that recognize specific tumor-associated peptides bound to class I MHC molecules. Of several cellular proteins involved in T cell:target-cell interaction, the TCR determines specificity of binding; however, the relative amount of its contribution to cellular avidity remains unknown. To study the relationship between TCR affinity and cellular avidity, with the intent of identifying optimal TCR for gene therapy, we derived 24 MART-1:27-35 (MART-1) melanoma Ag-reactive tumor-infiltrating lymphocyte (TIL) clones from the tumors of five patients. These MART-1-reactive clones displayed a wide variety of cellular avidities. alpha and beta TCR genes were isolated from these clones, and TCR RNA was electroporated into the same non-MART-1-reactive allogeneic donor PBMC and TIL. TCR recipient cells gained the ability to recognize both MART-1 peptide and MART-1-expressing tumors in vitro, with avidities that closely corresponded to the original TCR clones (p = 0.018-0.0003). Clone DMF5, from a TIL infusion that mediated tumor regression clinically, showed the highest avidity against MART-1 expressing tumors in vitro, both endogenously in the TIL clone, and after RNA electroporation into donor T cells. Thus, we demonstrated that the TCR appeared to be the core determinant of MART-1 Ag-specific cellular avidity in these activated T cells and that nonreactive PBMC or TIL could be made tumor-reactive with a specific and predetermined avidity. We propose that inducing expression of this highly avid TCR in patient PBMC has the potential to induce tumor regression, as an "off-the-shelf" reagent for allogeneic melanoma patient gene therapy.

CD4+ count-guided interruption of antiretroviral treatment

BACKGROUND

Despite declines in morbidity and mortality with the use of combination antiretroviral therapy, its effectiveness is limited by adverse events, problems with adherence, and resistance of the human immunodeficiency virus (HIV).

METHODS

We randomly assigned persons infected with HIV who had a CD4+ cell count of more than 350 per cubic millimeter to the continuous use of antiretroviral therapy (the viral suppression group) or the episodic use of antiretroviral therapy (the drug conservation group). Episodic use involved the deferral of therapy until the CD4+ count decreased to less than 250 per cubic millimeter and then the use of therapy until the CD4+ count increased to more than 350 per cubic millimeter. The primary end point was the development of an opportunistic disease or death from any cause. An important secondary end point was major cardiovascular, renal, or hepatic disease.

RESULTS

A total of 5472 participants (2720 assigned to drug conservation and 2752 to viral suppression) were followed for an average of 16 months before the protocol was modified for the drug conservation group. At baseline, the median and nadir CD4+ counts were 597 per cubic millimeter and 250 per cubic millimeter, respectively, and 71.7% of participants had plasma HIV RNA levels of 400 copies or less per milliliter. Opportunistic disease or death from any cause occurred in 120 participants (3.3 events per 100 person-years) in the drug conservation group and 47 participants (1.3 per 100 person-years) in the viral suppression group (hazard ratio for the drug conservation group vs. the viral suppression group, 2.6; 95% confidence interval [CI], 1.9 to 3.7; P<0.001). Hazard ratios for death from any cause and for major cardiovascular, renal, and hepatic disease were 1.8 (95% CI, 1.2 to 2.9; P=0.007) and 1.7 (95% CI, 1.1 to 2.5; P=0.009), respectively. Adjustment for the latest CD4+ count and HIV RNA level (as time-updated covariates) reduced the hazard ratio for the primary end point from 2.6 to 1.5 (95% CI, 1.0 to 2.1).

CONCLUSIONS

Episodic antiretroviral therapy guided by the CD4+ count, as used in our study, significantly increased the risk of opportunistic disease or death from any cause, as compared with continuous antiretroviral therapy, largely as a consequence of lowering the CD4+ cell count and increasing the viral load. Episodic antiretroviral therapy does not reduce the risk of adverse events that have been associated with antiretroviral therapy. (ClinicalTrials.gov number, NCT00027352 [ClinicalTrials.gov].).

Recognition of fresh human tumor by human peripheral blood lymphocytes transduced with a bicistronic retroviral vector encoding a murine anti-p53 TCR

The p53 protein is markedly up-regulated in a high proportion of human malignancies. Using an HLA-A2 transgenic mouse model, it was possible to isolate high-avidity murine CTLs that recognize class I-restricted human p53 epitopes. We isolated the alpha- and beta-chain of a TCR from a highly avid murine CTL clone that recognized the human p53(264-272) epitope. These genes were cloned into a retroviral vector that mediated high efficiency gene transfer into primary human lymphocytes. Efficiencies of >90% for gene transfer into lymphocytes were obtained without selection for transduced cells. The p53 TCR-transduced lymphocytes were able to specifically recognize with high-avidity, peptide-pulsed APCs as well as HLA-A2.1+ cells transfected with either wild-type or mutant p53 protein. p53 TCR-transduced cells demonstrated recognition and killing of a broad spectrum of human tumor cell lines as well as recognition of fresh human tumor cells. Interestingly, both CD8+ and CD4+ subsets were capable of recognizing and killing target cells, stressing the potential application of such a CD8-independent TCR molecule that can mediate both helper and cytotoxic responses. These results suggest that lymphocytes genetically engineered to express anti-p53 TCR may be of value for the adoptive immunotherapy of patients with a variety of common malignancies.

High-efficiency transfection of primary human and mouse T lymphocytes using RNA electroporation

The use of nonviral gene transfer methods in primary lymphocytes has been hampered by low gene transfer efficiency and high transfection-related toxicity. In this report, high gene transfection efficiency with low transfection-related toxicity was achieved by electroporation using in vitro-transcribed mRNA. Using these methods, >90% transgene expression with >80% viable cells was observed in stimulated primary human and murine T lymphocytes transfected with GFP or mCD62L. Electroporation of unstimulated human PBMCs or murine splenocytes with GFP RNA yielded 95 and 56% GFP+ cells, respectively. Electroporation of mRNA for NY-ESO-1, MART-1, and p53 antigen-specific TCRs into human T lymphocytes redirected these lymphocytes to recognize melanoma cell lines in an MHC-restricted manner. The onset of gene expression was rapid (within 30 min) and durable (up to 7 days postelectroporation) using both GFP and TCR-mediated recognition of target cells. There was no adverse effect observed on the T lymphocytes subjected to RNA electroporation evaluated by cell growth rate, annexin-V staining of apoptotic cells, BrdU incorporation, tumor antigen-specific recognition or antigen-specific TCR affinity. The results of this study indicate that mRNA electroporation provides a powerful tool to introduce genes into both human and murine primary T lymphocytes.

The second-look operation improves survival in suboptimally debulked stage III ovarian cancer patients

In a single-institution retrospective cohort study, 230 patients were treated for stage III primary ovarian cancer and 175 became eligible for second-look operations by virtue of a complete clinical response after primary surgical cytoreduction and platinum-based combination chemotherapy. Of these, 109 underwent a second-look operation. Optimal primary cytoreduction was defined as residual disease < or =1 cm. Median follow-up was 68.3 months. Five-year survival for all the 230 stage III ovarian cancers was 43.4%. Among all eligible patients (n = 175), there was no survival difference (P = 0.67) in those having second look (57.3%, 5-year survival) versus no second look (48.7%). In those patients with optimal primary cytoreduction (n = 118), there was no survival advantage to second look (69% versus 61%, P = 0.7). However, in those with suboptimal primary cytoreduction (n = 47), 5-year survival was 36% in those having second look versus only 13% in those refusing second look (P < 0.05). Multivariate analysis identified second-look surgery as the only significant independent prognostic variable affecting survival (RR = 0.321, P < 0.04). Patients with suboptimal debulking at primary surgery for stage III ovarian cancer appear to achieve a survival benefit from second-look surgical procedures, presumably from the early identification and treatment of residual disease.