Tumor-infiltrating Lymphocytes Therapy Research Articles

Abstract LB150: Clinical Feasibility and Treatment Outcomes with Unselected Autologous Tumor Infiltrating Lymphocyte Therapy in Patients with Advanced Cutaneous Melanoma

Abstract Introduction: A minority of patients (pts) with advanced melanoma achieve long-term survival with immunotherapy and those who relapse following immune checkpoint inhibition (ICI) or BRAFi have limited treatment options. The intrinsic anti-tumor activity and broad neoantigen-specific TCR repertoire of unselected autologous TIL may provide advantages over other treatments in solid tumors, including ICI-refractory melanoma. Methods: This is a retrospective analysis of a single-center experience of TIL for treatment of advanced cutaneous melanoma. Unselected autologous young TIL derived from digested tumor tissue were manufactured under a MHRA Manufacturing Specials license. Pts with advanced cutaneous melanoma and no other treatment options received non-myeloablative lymphodepleting chemotherapy (cyclophosphamide 60 mg/kg/d x 2d, fludarabine 25 mg/m2/d x 5 d [Cy/Flu]), followed by TIL infusion and post-TIL high-dose (HD) IL-2 (600,000-720,000 IU/Kg) on a compassionate use basis. Efficacy for 15 imaging-evaluable pts was reported by investigator assessment of CT/MRI per RECIST 1.1; 6 additional pts were followed using non-RECIST 1.1 imaging (PET) and clinical monitoring. Clinically significant adverse events (AEs) with onset post-TIL infusion were reported for all treated pts. Data cutoff date: 31-DEC-2019. Results: Between OCT-2011 and AUG-2019, 21 pts with advanced cutaneous melanoma were treated with Cy/Flu, TIL (median 31.9 x109 cells infused), and HD IL-2 (median 8 doses). All had high-risk metastatic disease (median 4 sites, stage IV M1d [38%]), an average of 3 prior therapies (any ICI [91%], PD-1 [57%], BRAFi [52%], and MEKi [24%]). With a median follow up of 52.2 mos, the response rate in imaging-evaluable pts (n=15) was 53% with a CR rate of 13%; DCR was 73% including 3 (20%) pts with stable disease. Additional durable responses were observed in the 6 pts followed by PET and clinical monitoring. Responses were generally consistent across subgroups including age, number of disease sites, tumor burden, brain metastases, number of prior lines of therapies, prior PD-1 blockade, prior BRAFi, and prior MEKi. For all treated pts, the median survival was 21.3 mos. Toxicity was generally self-limited and consistent with Cy/Flu and HD IL-2. Common AEs (≥20%, any grade) were thrombocytopenia (62%), pyrexia (57%), rigors (43%), neutropenia (29%), tachycardia (29%), pulmonary edema (24%), and vascular leak (24%); no treatment-related deaths were observed. Conclusion: The high response rate observed in this series exceeds the 41% ORR estimated for TIL in advanced cutaneous melanoma (meta-analysis by Dafni et al. Ann Oncol., 2019) and highlights the successful bench-to-bedside application of unselected autologous TIL to address unmet medical need in advanced melanoma. Use of tumor digests as starting material for manufacturing of TIL demonstrates feasibility of this approach. A multicenter Phase 2 trial of this therapy in advanced melanoma is planned for 2021. Citation Format: Robert E. Hawkins, Yizhou Jiang, Paul C. Lorigan, Fiona C. Thistlethwaite, Manon Pillai, Martine Thomas, Natalia Kirilova, John S. Bridgeman, Gray Kueberuwa, Ryan S. Guest, Zachary J. Roberts. Clinical Feasibility and Treatment Outcomes with Unselected Autologous Tumor Infiltrating Lymphocyte Therapy in Patients with Advanced Cutaneous Melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB150.

Clinical efficacy of T-cell therapy after short-term BRAF-inhibitor priming in patients with checkpoint inhibitor-resistant metastatic melanoma

PurposeDespite impressive response rates following adoptive transfer of autologous tumor-infiltrating lymphocytes (TILs) in patients with metastatic melanoma, improvement is needed to increase the efficacy and broaden the applicability of this...

Stem cell properties of GT101, a tumor infiltrating lymphocyte (TIL) product with multiple indications.

e14506 Background: Tumor infiltrating lymphocyte (TIL) is a kind of adoptive T cell therapy that has demonstrated clinical benefits in several types of solid tumors. GT101 is an autologous TIL therapy for the treatment of multiple solid tumors. Previous studies showed that in vitro expansion resulted in over 80% terminally differentiated effector T cells in the final TIL products, which may show good cytotoxicity but weak capability of persistence and proliferation in vivo. Herein we present phenotype and function characterization of our TIL product GT101 with a focus on its stemness attributes. Methods: We have produced more than 30 batches of GT101 TIL samples from 10 different cancer indications and analyzed their proliferation, cytokine production and phenotype at preREP and/or REP stage. Results: GT101 products keep a consistent T cell phenotype and good proliferation capacity, and are capable of secreting large amounts of cytokines after stimulation by anti-CD3/CD28 antibody, reflecting its good functionality. The residues in the final products, such as feeder cells and tumor cells, are below the detection limit. In contrast to equivalent TIL products previously reported across the world, we find that GT101 features a manufacturing process that preserves the stem cell characteristics of T cells. Analysis of all the 30 GT101 TIL samples demonstrates that the average percentage of central memory T cells (Tcm) and naïve T cells is 40-50% and 10-20% respectively in both CD8+ and CD4+ populations at the end of preREP stage. Meanwhile, CD8+TCF1+ cells are close to 50%, mainly in the form of PD-1-. In the phase of REP, the stemness of T cell is still well maintained—the average proportion of both Tcm and naïve T cells only decreases by about 5%, and that of CD8+TCF1+ cells down by about 10%. Conclusions: In general, GT101 demonstrates good stemness with a higher percentage of Tcm and TCF1+ than equivalent products previously reported across the world, suggesting better performance in persistence and proliferation in clinic.

In-depth immune and molecular profiling of melanoma patients receiving adoptive T-cell therapy reveals biomarkers of efficacy in ATATIL study.

2533 Background: Adoptive cell therapy (ACT) using tumor-infiltrating lymphocytes (TIL) has demonstrated a curative potential for patients with metastatic melanoma (MM). Nevertheless, activity remains unsatisfactory in many patients, requiring development of biomarkers that predict therapeutic efficacy. We report results of a single-center phase I study to assess feasibility, safety and efficacy of TIL-ACT in MM patients (NCT03475134). Methods: Patients with MM refractory to at least one prior line of therapy received TIL therapy with lymphodepleting chemotherapy before T-cell infusion, followed by high-dose interleukin-2. RDG- and FDG-PET imaging was performed before and after TIL infusion. Multispectral immuno-fluorescence (mIF) imaging and bulk-RNA sequencing (Seq) were performed on tumor samples pre-ACT and post-ACT (day+30 and upon progression). Single-cell RNA-Seq and TCR-Seq were performed on pre-ACT tumor and ACT product, as well as on tumor-reactive and neoantigen-specific TILs and on longitudinal blood samples. Results: As of 02/02/2021, thirteen patients (enrolled between March 2018 and December 2020) have successfully completed TIL-ACT therapy, with a median follow-up of 9.5 months (IQR 3.0 -24.6). Median age was 53 years (range 20-69) and all were previously treated with PD-1 based blockade. Median number of TILs infused was 55.0 x109 cells (range 12.8-84.7). The best overall response rate by RECIST 1.1 and disease control rate in evaluable patients was 41.7% (5/12) and 50% (6/12) respectively at 3 months. Two patients have an ongoing near-complete response at 3 years. Up to data cut-off, 10 patients have progressed by RECIST v1.1, with median PFS of 4.8 months (95% CI 1.5 - 9.6), while median OS is not reached. mIF revealed biomarkers of response, which may allow proper identification of patients in subsequent studies. In addition, deep sequencing of bulk and neoepitope-specific TIL clonotypes highlighted transcriptomic signatures revealing cell programs regulating in vitro expansion, in vivo blood persistence as well as tumor infiltration post-ACT. RGD-PET data will also be presented. Conclusions: We demonstrate reproducibility of TIL-ACT in our center, consistently with previous reports. Comprehensive translational studies reveal immune correlates of clinical responses that contribute to the understanding of mechanisms of TIL potency and will guide the development of next-generation cell products. Clinical trial information: NCT03475134.

Lifileucel, a Tumor-Infiltrating Lymphocyte Therapy, in Metastatic Melanoma.

PURPOSEEffective treatment options are limited for patients with advanced (metastatic or unresectable) melanoma who progress after immune checkpoint inhibitors and targeted therapies. Adoptive cell therapy using tumor-infiltrating lymphocytes has demonstrated efficacy in advanced melanoma. Lifileucel is an autologous, centrally manufactured tumor-infiltrating lymphocyte product.METHODSWe conducted a phase II open-label, single-arm, multicenter study in patients with advanced melanoma who had been previously treated with checkpoint inhibitor(s) and BRAF ± MEK targeted agents. Lifileucel was produced from harvested tumor specimens in central Good Manufacturing Practice facilities using a streamlined 22-day process. Patients received a nonmyeloablative lymphodepletion regimen, a single infusion of lifileucel, and up to six doses of high-dose interleukin-2. The primary end point was investigator-assessed objective response rate (ORR) per RECIST, version 1.1.RESULTSSixty-six patients received a mean of 3.3 prior therapies (anti–programmed death 1 [PD-1] or programmed death ligand 1 [PD-L1]: 100%; anticytotoxic T-lymphocyte-associated protein-4: 80%; BRAF ± MEK inhibitor: 23%). The ORR was 36% (95% CI, 25 to 49), with two complete responses and 22 partial responses. Disease control rate was 80% (95% CI, 69 to 89). Median duration of response was not reached after 18.7-month median study follow-up (range, 0.2-34.1 months). In the primary refractory to anti–PD-1 or PD-L1 therapy subset, the ORR and disease control rate were 41% (95% CI, 26 to 57) and 81% (95% CI, 66 to 91), respectively. Safety profile was consistent with known adverse events associated with nonmyeloablative lymphodepletion and interleukin-2.CONCLUSIONLifileucel demonstrated durable responses and addresses a major unmet need in patients with metastatic melanoma with limited treatment options after approved therapy, including the primary refractory to anti–PD-1 or PD-L1 therapy subset.

Randomized phase II trial of lymphodepletion plus adoptive cell transfer of tumor-infiltrating lymphocytes, with or without dendritic cell vaccination, in patients with metastatic melanoma

BackgroundThe adoptive transfer of tumor-infiltrating lymphocytes (TIL) has demonstrated robust efficacy in metastatic melanoma patients. Tumor antigen–loaded dendritic cells (DCs) are believed to optimally activate antigen-specific T lymphocytes. We hypothesized...

Systemic Delivery of Oncolytic Adenovirus to Tumors Using Tumor-Infiltrating Lymphocytes as Carriers.

Immunotherapy with tumor-infiltrating lymphocytes (TIL) or oncolytic adenoviruses, have shown promising results in cancer treatment, when used as separate therapies. When used in combination, the antitumor effect is synergistically potentiated due oncolytic adenovirus infection and its immune stimulating effects on T cells. Indeed, studies in hamsters have shown a 100% complete response rate when animals were treated with oncolytic adenovirus coding for TNFa and IL-2 (Ad5/3-E2F-D24-hTNFa-IRES-hIL2; TILT-123) and TIL therapy. In humans, one caveat with oncolytic virus therapy is that intratumoral injection has been traditionally preferred over systemic administration, for achieving sufficient virus concentrations in tumors, especially when neutralizing antibodies emerge. We have previously shown that 5/3 chimeric oncolytic adenovirus can bind to human lymphocytes for avoidance of neutralization. In this study, we hypothesized that incubation of oncolytic adenovirus (TILT-123) with TILs prior to systemic injection would allow delivery of virus to tumors. This approach would deliver both components in one self-amplifying product. TILs would help deliver TILT-123, whose replication will recruit more TILs and increase their cytotoxicity. In vitro, TILT-123 was seen binding efficiently to lymphocytes, supporting the idea of dual administration. We show in vivo in different models that virus could be delivered to tumors with TILs as carriers.

CD8+CD39+ T Cells Mediate Anti-Tumor Cytotoxicity in Bladder Cancer.

IntroductionAlthough immunotherapy works well in parts of patients with bladder cancer (BLCA), its overall response rate of anti-PD-1 inhibitors remains unsatisfactory. Besides, growing evidence shows that tumor-infiltrating lymphocytes (TILs) immunotherapy has demonstrated excellent efficacy in various cancers. Considering the huge heterogeneity and low overall survival rate of BLCA, it is urgent to explore the new immune checkpoints (ICs) or TILs therapy to improve the survival prognosis for BLCA patients.Materials and MethodsThe public bioinformatics databases were used to explore the prognostic value of 5 potential ICs targets (TIM-3, LAG-3, OX40, 4–1BB and CD39). A total of 46 BLCA patients undergoing surgical treatment at our hospital from May 2020 to October 2020 were enrolled in this study. The expressions of PD-1, TIM-3, LAG-3, OX40, 4–1BB, and CD39 in T cells of BLCA patients were explored by flow cytometry, and the correlation between different subgroups of T cells and clinicopathological parameters was analyzed. Besides, the mouse CD4+CD39+ T cells, CD4+CD39- T cells, CD8+CD39+ T cells, and CD8+CD39- T cells were sorted and co-cultured with MB49 bladder cancer cell lines in vitro to investigate the potential biomarker of tumor-reactive TILs.ResultsPublic bioinformatics databases analyses show that only the high expression of CD39 was significantly associated with advanced tumor stage (P < 0.001) and tend to result in a worse survival rate. In our study, the elevated expression of CD39 in CD4+/CD8+ T cells were significantly associated with the pathological T stage (pT <2, P = 0.041) and papillary tumor (P = 0.038). Moreover, the CD8+CD39+ T cells showed a stronger tumor-killing effect and produced a higher level of IFN-γ than other T cell populations.ConclusionCD39 may be a potential prognostic marker in BLCA, and CD8+CD39+ T cells may be selected as tumor-reactive and killing T cells for TILs therapy.

The Glutaminase Inhibitor CB-839 (Telaglenastat) Enhances the Antimelanoma Activity of T-Cell-Mediated Immunotherapies.

Immune-checkpoint inhibitors and adoptive tumor-infiltrating lymphocyte (TIL) therapies have profoundly improved the survival of patients with melanoma. However, a majority of patients do not respond to these agents, and many responders experience disease relapse. Although numerous innovative treatments are being explored to offset the limitations of these agents, novel therapeutic combinations with immunotherapies have the potential to improve patient responses. In this study, we evaluated the antimelanoma activity of immunotherapy combinations with Telaglenastat (CB-839), a potent glutaminase inhibitor (GLSi) that has favorable systemic tolerance. In in vitro TIL:tumor coculture studies, CB-839 treatment improved the cytotoxic activity of autologous TILs on patient-derived melanoma cells. CB-839 treatment decreased the conversion of glutamine to alpha-ketoglutarate (αKGA) more potently in tumor cells versus TILs in these cocultures. These results suggest that CB-839 may improve immune function in a tumor microenvironment by differentially altering tumor and immune cell metabolism. In vivo CB-839 treatment activated melanoma antigen-specific T cells and improved their tumor killing activity in an immune-competent mouse model of adoptive T-cell therapy. Additionally, the combination of CB-839 with anti-PD1 or anti-CTLA4 antibodies increased tumor infiltration by effector T cells and improved the antitumor activity of these checkpoint inhibitors in a high mutation burden mouse melanoma model. Responsiveness to these treatments was also accompanied by an increase of interferon gamma (IFNγ)-associated gene expression in the tumors. Together, these results provide a strong rationale for combining CB-839 with immune therapies to improve efficacy of these treatments against melanoma.

The Factors Affecting Expansion of Reactive Tumor Infiltrating Lymphocytes (TIL) From Bladder Cancer and Potential Therapeutic Applications.

Tumor infiltrating lymphocytes (TIL) therapy was shown to provide durable objective response in patients with metastatic melanoma. As a fundamental first step to bring TIL therapy to clinical use, identification of patients whose tumors yield optimal numbers of reactive TIL is indispensable. We have previously shown that expansion of tumor reactive TIL from primary bladder tumors and lymph node metastases is feasible. Here, we performed TIL harvesting from additional surgical specimens (additional 31 primary tumors and 10 lymph nodes) to generate a heterogenous cohort of 53 patients with bladder cancer (BC) to evaluate the tumor characteristics that lead to tumor-reactive TIL expansion. Among a total of 53 patients, overall TIL growth from tumor samples were 37/53 (69.8%) and overall anti-tumor reactive TIL were 26/35 (74.3%). Mixed urothelial carcinoma is associated with higher anti-tumor reactivity of expanded TIL than pure urothelial carcinoma (89.5% vs. 56.3%, p=0.049). The anti-tumor reactivity of expanded TIL from primary tumors previously treated with BCG immunotherapy were lower (33.3% vs. 82.6%, p=0.027) although T-cell phenotype (CD3+, CD4+, CD8+, and CD56+) was similar regardless prior of BCG therapy. Addition of agonistic 4-1BB antibody in culture media with IL-2 improved the number of expanded TIL from primary tumors previously treated with BCG immunotherapy. There was no significant difference between basal and luminal subtype tumors in terms of viable and reactive TIL growth. Our study demonstrates that TIL expansion is feasible across all BC patients and BC subtypes, and we suggest that TIL therapy can be a reasonable treatment strategy for various manifestations of BC.

Cytokine-Coding Oncolytic Adenovirus TILT-123 Is Safe, Selective, and Effective as a Single Agent and in Combination with Immune Checkpoint Inhibitor Anti-PD-1.

Oncolytic viruses provide a biologically multi-faceted treatment option for patients who cannot be cured with currently available treatment options. We constructed an oncolytic adenovirus, TILT-123, to support T-cell therapies and immune checkpoint inhibitors in solid tumors. Adenoviruses are immunogenic by nature, are easy to produce in large quantities, and can carry relatively large transgenes. They are the most commonly used gene therapy vectors and are well tolerated in patients. TILT-123 expresses two potent cytokines, tumor necrosis factor alpha and interleukin-2, to stimulate especially the T-cell compartment in the tumor microenvironment. Before entering clinical studies, the safety and biodistribution of TILT-123 was studied in Syrian hamsters and in mice. The results show that TILT-123 is safe in animals as monotherapy and in combination with an immune checkpoint inhibitor anti-PD-1. The virus treatment induces acute changes in circulating immune cell compartments, but the levels return to normal by the middle of the treatment period. The virus is rapidly cleared from healthy tissues, and it does not cause damage to vital organs. The results support the initiation of a phase 1 dose-escalation trial, where melanoma patients receiving a tumor-infiltrating lymphocyte therapy are treated with TILT-123 (NCT04217473).

The mutational load and a T-cell inflamed tumour phenotype identify ovarian cancer patients rendering tumour-reactive T cells from PD-1+ tumour-infiltrating lymphocytes

BackgroundAdoptive immunotherapy with tumour-infiltrating lymphocytes (TIL) may benefit from the use of selective markers, such as PD-1, for tumour-specific T-cell enrichment, and the identification of predictive factors that help identify those patients capable of rendering tumour-reactive TILs. We have investigated this in ovarian cancer (OC) patients as candidates for TIL therapy implementation.MethodsPD-1− and PD-1+ CD8 TILs were isolated from ovarian tumours and expanded cells were tested against autologous tumour cells. Baseline tumour samples were examined using flow cytometry, multiplexed immunofluorescence and Nanostring technology, for gene expression analyses, as well as a next-generation sequencing gene panel, for tumour mutational burden (TMB) calculation.ResultsTumour-reactive TILs were detected in half of patients and were exclusively present in cells derived from the PD-1+ fraction. Importantly, a high TIL density in the fresh tumour, the presence of CD137+ cells within the PD-1+CD8+ TIL subset and their location in the tumour epithelium, together with a baseline T-cell-inflamed genetic signature and/or a high TMB, are features that identify patients rendering tumour-reactive TIL products.ConclusionWe have demonstrated that PD-1 identifies ovarian tumour-specific CD8 TILs and has uncovered predictive factors that identify OC patients who are likely to render tumour-specific cells from PD-1+ TILs.

T cells expanded from renal cell carcinoma display tumor-specific CD137 expression but lack significant IFN-γ, TNF-α or IL-2 production

ABSTRACT Metastatic renal cell carcinoma (RCC) has a poor prognosis. Recent advances have shown beneficial responses to immune checkpoint inhibitors, such as anti-PD-1/PD-L1 antibodies. As only a subset of RCC patients respond, alternative strategies should be explored. Patients refractory to anti-PD-1 therapy may benefit from autologous tumor-infiltrating lymphocyte (TIL) therapy. Even though efficient TIL expansion was reported from RCC lesions, it is not well established how many RCC TIL products are tumor-reactive, how well they produce pro-inflammatory cytokines in response to autologous tumors, and whether their response correlates with the presence of specific immune cells in the tumor lesions. We here compared the immune infiltrate composition of RCC lesions with that of autologous kidney tissue of 18 RCC patients. Tcell infiltrates were increased in the tumor lesions, and CD8+ Tcell infiltrates were primarily of effector memory phenotype. Nine out of 16 (56%) tested TIL products we generated were tumor-reactive, as defined by CD137 upregulation after exposure to autologous tumor digest. Tumor reactivity was found in particular in TIL products originating from tumors with ahigh percentage of infiltrated Tcells compared to autologous kidney, and increased CD25 expression on CD8+ Tcells. Importantly, although TIL products had the capacity to produce the key effector cytokines IFN-γ, TNF-α or IL-2, they failed to produce significant amounts in response to autologous tumor digests. In conclusion, TIL products from RCC lesions contain tumor-reactive Tcells. Their restricted tumor-specific cytokine production requires further investigation of immunosuppressive factors in RCC and subsequent optimization of RCC-derived TIL culture conditions.

Bilateral Optic Neuropathy Secondary to Toxicity From Tumor-Infiltrating Lymphocytes Therapy Combined With Checkpoint Blockade.

Bilateral Optic Neuropathy Secondary to Toxicity From Tumor-Infiltrating Lymphocytes Therapy Combined With Checkpoint Blockade.

Systemic and intravesical adoptive cell therapy of tumor-reactive T cells can decrease bladder tumor growth in vivo

BackgroundThe therapeutic armamentarium of bladder cancer has been recently enriched with the introduction of new therapies including immune checkpoint inhibitors, receptor tyrosine kinase inhibitors and antibody drug conjugates, however treatment...

1022MO Clinical potential of adoptive cell therapy with tumour infiltrating lymphocytes therapy in combination with checkpoint inhibitors in non-melanoma patients

1022MO Clinical potential of adoptive cell therapy with tumour infiltrating lymphocytes therapy in combination with checkpoint inhibitors in non-melanoma patients

1052P Genetic modification of Iovance’s TIL through TALEN-mediated knockout of PD-1 as a strategy to empower TIL therapy for cancer

Iovance’s autologous tumor-infiltrating lymphocyte (TIL) product has reported efficacy results in metastatic melanoma and cervical cancer patients that reflect an ORR of 36.4% and 44%, respectively. While this appears superior to standard of care, we seek further improvements by creating a new generation of TIL. One potential limitation of TIL therapy is inactivation by the PD-1/PD-L1 pathway, which provides rationale for combining TIL with PD-1 blockade. Here, we abrogate PD-1 within the TIL product to reduce PD-L1-dependent TIL inactivation.

The Outcome of Ex Vivo TIL Expansion Is Highly Influenced by Spatial Heterogeneity of the Tumor T-Cell Repertoire and Differences in Intrinsic In Vitro Growth Capacity between T-Cell Clones.

During our efforts to develop tumor-infiltrating lymphocyte (TIL) therapy to counter the devastating recurrence rate in patients with primary resectable pancreatic ductal adenocarcinoma (PDA), we found that PDA TILs can readily be expanded in vitro and that the majority of resulting TIL cultures show reactivity against the autologous tumor. However, the fraction of tumor-reactive T cells is low. We investigated to which extent this was related to the in vitro expansion. We compared the clonal composition of TIL preparations before and after in vitro expansion using T-cell receptor (TCR) deep sequencing. Our findings for PDA were benchmarked to experiments with melanoma TILs. We found that the TIL TCR repertoire changes dramatically during in vitro expansion, leading to loss of tumor- dominant T-cell clones and overgrowth by newly emerging T-cell clones that are barely detectable in the tumor. These changes are primarily driven by differences in the intrinsic in vitro expansion capacity of T-cell clones. Single-cell experiments showed an association between poor proliferative capacity and expression of markers related to antigen experience and dysfunction. Furthermore, we found that spatial heterogeneity of the TIL repertoire resulted in TCR repertoires that are greatly divergent between TIL cultures derived from distant tumor samples of the same patient. Culture-induced changes in clonal composition are likely to affect tumor reactivity of TIL preparations. TCR deep sequencing provides important insights into the factors that govern the outcome of in vitro TIL expansion and thereby a path toward optimization of the production of TIL preparations with high therapeutic efficacy.See related commentary by Lozano-Rabella and Gros, p. 4177.

Abstract 2175: KSQ-001: A CRISPR/Cas9-engineered tumor infiltrating lymphocyte (eTILTM) therapy for solid tumors

Abstract Adoptive cell therapy (ACT) with ex vivo expanded tumor infiltrating lymphocytes (TIL) offers a potentially transformative treatment for treatment refractory solid tumors. However, the immunosuppressive tumor microenvironment (TME) limits the effectiveness of TIL therapy. To systematically identify targets that have the potential to improve T-cell function in the TME, we conducted two genome-wide CRISPR/Cas9 functional screens of immune cells using our proprietary CRISPRomics® platform. The first screen employed primary mouse T cells and assessed in vivo T cell infiltration into tumors by measuring sgRNA guide enrichment. Notably, this screen identified clinically active targets, such as PD-1, and identified multiple targets, including Cell Therapy-1 (CT-1), that demonstrated anti-tumor T-cell function superior to PD-1. The potential of inactivating CT-1 for ACT was subsequently validated in both PD-1 sensitive and insensitive syngeneic tumor models in the absence of any additional conditioning regimens. CT-1 edited T cells established durable anti-tumor memory characterized by a T central memory state. A second genome-wide screen employed human TIL and assessed the impact of gene inactivation on human TIL expansion under standard manufacturing conditions. This screen also identified CT-1 as a top target. We therefore prioritized the development of KSQ-001, an engineered TIL (eTILTM) therapy, created via CRISPR/Cas9-mediated editing of CT-1. Potent and selective sgRNAs targeting CT-1 were identified and characterized, and manufacturing methods to engineer human TIL with high efficiency have been developed. Together, these data demonstrate that our CRISPRomics® platform enables comprehensive target identification and validation of compelling new targets for the development of robust eTILTM therapies, and support the clinical evaluation of KSQ-001 as a next generation adoptive cell therapy in a variety of treatment-refractory solid tumors. Citation Format: Mike Schlabach, Nick Colletti, Anja Hohmann, Christopher Wrocklage, Hugh Gannon, Alejandra Falla, Noah Tubo, Robert A. LaMothe, Caroline Bullock, Pete T. Mitchell, Nafeeza Hafeez, Suphinya Sathithloetsakun, Paula E. Grasberger, Isabelle Le Mercier, Tracy E. Garrett, Sean Keegan, Sol Shenker, Charlotte Franco, Frank Stegmeier, Gregory V. Kryukov, Louise Cadzow, Micah Benson. KSQ-001: A CRISPR/Cas9-engineered tumor infiltrating lymphocyte (eTILTM) therapy for solid tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2175.

Sirt2 Inhibition Enhances Metabolic Fitness and Effector Functions of Tumor-Reactive T Cells

Dysregulated metabolism is a key driver of maladaptive tumor-reactive T lymphocytes within the tumor microenvironment. Actionable targets that rescue the effector activity of antitumor Tcells remain elusive. Here, we report that the Sirtuin-2 (Sirt2) NAD+-dependent deacetylase inhibits Tcell metabolism and impairs Tcell effector functions. Remarkably, upregulation of Sirt2 in human tumor-infiltrating lymphocytes (TILs) negatively correlates with response to TIL therapy in advanced non-small-cell lung cancer. Mechanistically, Sirt2 suppresses Tcell metabolism by targeting key enzymes involved in glycolysis, tricarboxylic acid-cycle, fatty acid oxidation, and glutaminolysis. Accordingly, Sirt2-deficient murine Tcells exhibit increased glycolysis and oxidative phosphorylation, resulting in enhanced proliferation and effector functions and subsequently exhibiting superior antitumor activity. Importantly, pharmacologic inhibition of Sirt2 endows human TILs with these superior metabolic fitness and effector functions. Our findings unveil Sirt2 as an unexpected actionable target for reprogramming Tcell metabolism to augment a broad spectrum of cancer immunotherapies.