A phase I clinical trial of PSMA-directed/TGFβ-insensitive CAR-T cells in metastatic castration-resistant prostate cancer.

2020 ◽  
Vol 38 (6_suppl) ◽  
pp. TPS269-TPS269
Author(s):  
Vivek Narayan ◽  
Whitney Gladney ◽  
Gabriela Plesa ◽  
Neha Vapiwala ◽  
Erica L. Carpenter ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Clinical Trial ◽  
T Cells ◽  
Single Dose ◽  
Peripheral Blood ◽  
Therapeutic Potential ◽  
Dominant Negative ◽  
Therapeutic Window ◽  
Car T Cells ◽  
Car T

TPS269 Background: Adoptive immunotherapy with Chimeric Antigen Receptor (CAR)-T cells is a novel approach for the treatment of prostate cancer. However, the prostate cancer immunosuppressive microenvironment, including high levels of TGFβ, may limit the therapeutic potential of re-directed T cells upon tumor infiltration. The inhibition of TGFβ signaling via co-expression of a dominant negative TGFβ receptor (TGFβRdn) can enhance antitumor immunity. Co-expression of TGFβRdn on PSMA-redirected CAR-T cells in in vivo disseminated tumor models led to increased T cell proliferation, enhanced cytokine secretion, resistance to exhaustion, long-term persistence, and greater induction of tumor eradication. Methods: We are conducting a first-in-human phase 1 clinical trial evaluating the safety and preliminary efficacy of lentivirally-transduced PSMA-redirected/TGFβ-insensitive CAR-T cells (CART-PSMA-TGFβRdn) in metastatic CRPC (NCT03089203). In a 3+3 dose-escalation design, patients received a single dose of 1-3 x 107/m2 (Cohort 1) or 1-3 x 108/m2 (Cohort 2) CART-PSMA-TGFβRdn cells without lymphodepleting chemotherapy. In Cohort 3, 1-3 x 108/m2 CART-PSMA-TGFβRdn cells are administered following a lymphodepleting chemotherapy regimen of cyclophosphamide and fludarabine (cy/flu). A currently accruing modified protocol seeks to optimize the therapeutic window with CART-PSMA-TGFβRdn (CAR-T dose of 1-3 x 107/m2 following lymphodepleting cy/flu). Eight patients have received a single dose of CART-PSMA-TGFβRdn. CAR-T expansion and persistence in peripheral blood and trafficking to target tissues is evaluated via quantitative PCR of CART-PSMA-TGFβRdn DNA. Bioactivity of CAR-T cells in peripheral blood is evaluated via multiplex immunoassays. Additional correlative analyses will interrogate the therapeutic contribution of TGFβRdn, as well as early markers of response and resistance to CART-PSMA-TGFβRdn therapy. Clinical trial information: NCT03089203.

A phase I clinical trial of PSMA-directed/TGFβ-insensitive CAR-T cells in metastatic castration-resistant prostate cancer.

2019 ◽  
Vol 37 (7_suppl) ◽  
pp. TPS347-TPS347 ◽  
Author(s):  
Vivek Narayan ◽  
Whitney Gladney ◽  
Gabriela Plesa ◽  
Neha Vapiwala ◽  
Erica Carpenter ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Clinical Trial ◽  
T Cells ◽  
T Cell ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Phase 1 ◽  
Dominant Negative ◽  
Car T Cells ◽  
Car T

TPS347 Background: Adoptive immunotherapy with Chimeric Antigen Receptor (CAR)-T cells has transformative potential for the treatment of cancer. However, a primary challenge to the success of these therapies in prostate cancer is the immunosuppressive microenvironment, including high levels of Transforming Growth Factor-beta (TGFβ), encountered by re-directed T cells upon tumor infiltration. Importantly, these immunosuppressive functions of TGFβ can be abrogated in T cells using a dominant negative TGFβ receptor (TGFβRdn), thereby enhancing antitumor immunity. In in vivo disseminated prostate cancer models, co-expression of TGFβRdn on PSMA-redirected CAR-T cells led to increased T cell proliferation, enhanced cytokine secretion, resistance to exhaustion, long-term persistence, and greater tumor eradication. Methods: We initiated a first-in-human phase 1 clinical trial to evaluate the safety and preliminary efficacy of lentivirally-transduced PSMA-directed/TGFβ-insensitive CAR-T cells (CART-PSMA-TGFβRdn) in men with metastatic CRPC. In preliminary dose-escalation cohorts, patients received a single dose of 1-3 x 107/m2 (Cohort 1) or 1-3 x 108/m2 (Cohort 2) CART-PSMA-TGFβRdn cells without lymphodepleting chemotherapy in a 3+3 design. In Cohort 3, patients will receive the MTD of CART-PSMA-TGFβRdn following a lymphodepleting regimen of cyclophosphamide and fludarabine. All patients provide newly obtained metastatic tumor biopsies at baseline, as well as on day +10 following the CAR-T cell infusion and at disease progression. CAR-T expansion and persistence in peripheral blood and trafficking to target tissues is evaluated via quantitative PCR of CART-PSMA-TGFβRdn DNA. Bioactivity of CART-PSMA-TGFβRdn cells is evaluated via multiplex immunoassays. Additional correlative studies include enumeration and phenotyping of circulating tumor cells and DNA. Cohorts 1 and 2 have been completed without observed DLT. Interestingly, a reversible cytokine release syndrome has been observed that is responsive to tocilizumab. Enrollment in Cohort 3 began in September 2018. Cohort expansions will examine serial CART-PSMA-TGFβRdn re-treatment strategies. Clinical trial information: NCT03089203.

A phase I clinical trial of PSMA-directed/TGFβ-insensitive CAR-T cells in metastatic castration-resistant prostate cancer.

2021 ◽  
Vol 39 (6_suppl) ◽  
pp. 125-125
Author(s):  
Vivek Narayan ◽  
Julie Barber-Rotenberg ◽  
Joseph Fraietta ◽  
Wei-Ting Hwang ◽  
Simon F. Lacey ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Clinical Trial ◽  
T Cells ◽  
Cell Expansion ◽  
Castration Resistant Prostate Cancer ◽  
Car T Cells ◽  
Castration Resistant ◽  
Car T ◽  
Tumor Biopsies ◽  
Dose Dependent

125 Background: Prostate specific membrane antigen (PSMA) is a highly expressed tumor-associated antigen potentially amenable to chimeric antigen receptor-modified T (CAR-T) cell therapy for castration-resistant prostate cancer (CRPC). However, a primary challenge to the success of CAR-T therapy in CRPC is the immunosuppressive microenvironment, characterized by high levels of TGFβ. The immunosuppressive functions of TGFβ can be inhibited in T cells using a dominant negative TGFβ receptor (TGFβRdn), thereby enhancing antitumor immunity. Methods: We conducted a first-in-human phase 1 clinical trial to evaluate the feasibility, safety and preliminary efficacy of PSMA-directed/TGFβ-insensitive CAR-T cells (CART-PSMA-TGFβRdn) in patients with metastatic CRPC (NCT03089203). In a 3+3 dose-escalation design, patients received a single dose of 1-3 x 107/m2 (Cohort 1) or 1-3 x 108/m2 (Cohort 2) CART-PSMA-TGFβRdn cells without lymphodepleting (LD) chemotherapy. In Cohort 3, one patient received 1-3 x 108/m2 CART-PSMA-TGFβRdn cells following a LD chemotherapy regimen of cyclophosphamide and fludarabine (Cy/Flu). In Cohort -3, three patients received 1-3 x 107/m2 CART-PSMA-TGFβRdn cells following Cy/Flu. Patients underwent metastatic tumor biopsies at baseline and on day 10 following treatment. Quantitative PCR of CART-PSMA-TGFβRdn DNA was performed at serial timepoints to evaluate for CAR-T expansion and persistence in peripheral blood and trafficking to target tissues. Multiplex cytokine analysis assessed CART-PSMA-TGFβRdn bioactivity. Results: Ten patients received CART-PSMA-TGFβRdn therapy across dose-level cohorts. All CART-PSMA-TGFβRdn infusion products met target transduction efficiency. Evaluation of CAR-T cellular kinetics demonstrated dose-dependent peripheral blood T cell expansion, as well as tumor tissue trafficking in post-treatment tumor biopsies. At Cohort 2 and above, 5 of 7 treated patients developed grade ≥2 cytokine release syndrome (CRS). Marked increases in inflammatory cytokines (IL-6, IL-15, IL-2, IFNγ) correlated with high-grade CRS events. One grade 5 adverse event (sepsis) occurred in Cohort 3. PSA decline was observed in 6 of 10 patients (median decline -33.2%, range -11.6% to -98.3%), and PSA30 response occurred in 4 of 10 patients (including one patient achieving PSA < 0.1 ng/mL). Conclusions: Adoptive cellular therapy with CART-PSMA-TGFβRdn is safe and feasible in patients with metastatic CRPC. A dose-dependent and lymphodepletion chemotherapy-dependent relationship was observed with CART-PSMA-TGFβRdn cell expansion, cytokine expression, CRS, and anti-tumor effect. Correlative cell trafficking and paired tumor Nanostring analyses will be presented. Future clinical investigations seek to enhance anti-tumor efficacy, while optimizing the therapeutic window. Clinical trial information: NCT03089203.

Dominant negative PD1 armored CART cells to induce remission in relapsed or refractory non-Hodgkin lymphoma (NHL) patients.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. e15028-e15028 ◽  
Author(s):  
Chengfei Pu ◽  
Liansheng Huang ◽  
Yang Su ◽  
Tianling Ding ◽  
Xibin Xiao ◽  
...  
Keyword(s):  
Clinical Trial ◽  
T Cells ◽  
Tumor Microenvironment ◽  
B Cell ◽  
Hodgkin Lymphoma ◽  
Dominant Negative ◽  
Car T Cells ◽  
Non Hodgkin Lymphoma ◽  
Car T ◽  
Tumor Killing

e15028 Background: The chimeric antigen receptor (CAR) T cell treatment has been demonstrated as an effective therapy to treat relapsed/refractory B cell malignancy. However, tumor microenvironment influences and affects the efficacy of CAR T treatment. For example, programmed death ligand 1/2 (PDL1/2) may inhibit the CAR T cells via interaction with up-regulated programmed cell death protein 1 (PD1) after T cells activation, suppressing the tumor-killing capability of the CAR T cells. Thus, blockade of the PD1-PDL1/2 interaction may enhance the anti-tumor efficacy of CAR T therapy. Methods: Here, we generated CAR T expressed an anti-CD19 CAR molecule and a dominant-negative PD1 molecule. Compared with conventional CART cells, these “armored” CART cells showed the enhanced capability of tumor-killing and more “memory-like” phenotypes after multiple-round tumor challenging. These results suggest dominant-negative PD1 molecules may protect CART cells from exhaustion in the tumor microenvironment. Results: Further, we reported the findings of a clinical trial for six relapsed or refractory B-cell non-Hodgkin lymphoma (NHLs) patients treated using our armored CAR T cells. These six patients failed multiple rounds of chemotherapy and radiotherapy. In the clinical trial, the patients were infused with autologous CAR T cells range from1×106/kg to 8×106/kg. PET/CT showed significant tumor shrinkage and SUV max declines in all six patients, and the ongoing responses were monitored. The best overall response rate (ORR)was 100%. Conclusions: The results of these six patients in the clinical trial showed that our armored CAR T cells achieved the significant anti-bulky lymphoma response while causing limited and tolerated cytokine release syndrome and central nervous system toxicity. Thus, dominant-negative PD1 molecules may increase CAR T cells persistence in patients, enhancing the efficacy of CAR T cells for treating blood cancer. Finally, dominant-negative PD1 can be used as a platform technology and may be applied to other adoptive cellular immunotherapies such as TCR-T or TIL in the treatment of solid tumors. We are continuing to monitor current patients and recruit more patients for the clinical trial.

109 Dominant-negative TGFβ receptor 2 enhances GPC3-targeting CAR-T cell efficacy against hepatocellular carcinoma

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A121-A121
Author(s):  
Nina Chu ◽  
Michael Overstreet ◽  
Ryan Gilbreth ◽  
Lori Clarke ◽  
Christina Gesse ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Dominant Negative ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

BackgroundChimeric antigen receptors (CARs) are engineered synthetic receptors that reprogram T cell specificity and function against a given antigen. Autologous CAR-T cell therapy has demonstrated potent efficacy against various hematological malignancies, but has yielded limited success against solid cancers. MEDI7028 is a CAR that targets oncofetal antigen glypican-3 (GPC3), which is expressed in 70–90% of hepatocellular carcinoma (HCC), but not in normal liver tissue. Transforming growth factor β (TGFβ) secretion is increased in advanced HCC, which creates an immunosuppressive milieu and facilitates cancer progression and poor prognosis. We tested whether the anti-tumor efficacy of a GPC3 CAR-T can be enhanced with the co-expression of dominant-negative TGFβRII (TGFβRIIDN).MethodsPrimary human T cells were lentivirally transduced to express GPC3 CAR both with and without TGFβRIIDN. Western blot and flow cytometry were performed on purified CAR-T cells to assess modulation of pathways and immune phenotypes driven by TGFβ in vitro. A xenograft model of human HCC cell line overexpressing TGFβ in immunodeficient mice was used to investigate the in vivo efficacy of TGFβRIIDN armored and unarmored CAR-T. Tumor infiltrating lymphocyte populations were analyzed by flow cytometry while serum cytokine levels were quantified with ELISA.ResultsArmoring GPC3 CAR-T with TGFβRIIDN nearly abolished phospho-SMAD2/3 expression upon exposure to recombinant human TGFβ in vitro, indicating that the TGFβ signaling axis was successfully blocked by expression of the dominant-negative receptor. Additionally, expression of TGFβRIIDN suppressed TGFβ-driven CD103 upregulation, further demonstrating attenuation of the pathway by this armoring strategy. In vivo, the TGFβRIIDN armored CAR-T achieved superior tumor regression and delayed tumor regrowth compared to the unarmored CAR-T. The armored CAR-T cells infiltrated HCC tumors more abundantly than their unarmored counterparts, and were phenotypically less exhausted and less differentiated. In line with these observations, we detected significantly more interferon gamma (IFNγ) at peak response and decreased alpha-fetoprotein in the serum of mice treated with armored cells compared to mice receiving unarmored CAR-T, demonstrating in vivo functional superiority of TGFβRIIDN armored CAR-T therapy.ConclusionsArmoring GPC3 CAR-T with TGFβRIIDN abrogates the signaling of TGFβ in vitro and enhances the anti-tumor efficacy of GPC3 CAR-T against TGFβ-expressing HCC tumors in vivo, proving TGFβRIIDN to be an effective armoring strategy against TGFβ-expressing solid malignancies in preclinical models.Ethics ApprovalThe study was approved by AstraZeneca’s Ethics Board and Institutional Animal Care and Use Committee (IACUC).

PSMA targeted armored chimeric antigen receptor (CAR) T-cells in patients with advanced mCRPC: A phase I experience.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. 2534-2534
Author(s):  
Matthew H. Carabasi ◽  
Meredith McKean ◽  
Mark N. Stein ◽  
Michael Thomas Schweizer ◽  
Jason J. Luke ◽  
...  
Keyword(s):  
T Cells ◽  
Dose Level ◽  
Chimeric Antigen Receptor ◽  
Antigen Receptor ◽  
Dominant Negative ◽  
Car T Cells ◽  
Car T ◽  
Level 1 ◽  
Immune Toxicity

2534 Background: CART-PSMA-TGFβRDN cells are autologous T cells engineered via lentiviral transduction to express a dominant negative form of TGFβRII (TGFβRDN) and a chimeric antigen receptor (CAR) with specificity to prostate specific membrane antigen (PSMA). The TGFβRDN renders CAR T cells resistant to TGFβ-mediated immunosuppression. CART-PSMA-02 is a multi-center, open-label, Phase 1 study evaluating the safety and feasibility of dosing patients with metastatic castration resistant prostate cancer (mCRPC) with CART-PSMA-TGFβRDN (NCT04227275). Methods: This is a 3+3 dose escalation study to determine the recommended phase 2 dose and schedule of CART-PSMA-TGFβRDN cells following lymphodepleting chemotherapy with cyclophosphamide and fludarabine. Single and fractionated doses are being evaluated. A cohort expansion will enroll patients to further explore the safety of the selected dose and schedule. Results: As of January 2021, 6 patients (pts) have been treated. Two pts were treated in the first dose level (1-3 x107 transduced T cells (TDN)). Four pts were treated in the second dose level (1-3 x 108 TDN with fractionated dosing). AEs occurring in ≥50 % of pts included cytokine release syndrome (CRS), anemia, thrombocytopenia, increased creatinine, nausea, fatigue, pyrexia and dehydration. No DLTs occurred in the 1st dose level. Four pts in the 2nd dose level developed CRS (3 Gr 1 and 1 Gr 2). One pt developed rapid G2 CRS that progressed to Gr 5 encephalopathy and Gr 5 multi-organ failure. Ferritin levels peaked at 56,974 ng/ml (baseline 2,903 ng/mL) despite aggressive immunosuppressive therapy including tocilizumab, dexamtheasone and anakinra. The post infusion cytokine profile indicated elevations in IL-1RA, TNF-alpha, VEGF, IL-10, MIP-1b, IFN-gamma, GM-CSF and notably lower levels of IL6 compared to published reports of CD19 CART-mediated CRS. Autopsy findings were consistent with HLH/MAS, confirming overactivity of the monocyte/macrophage compartment. Based on these observations, a modified immune toxicity management strategy that includes prophylactic anakinra (an IL1R antagonist) was instituted. Preliminary evidence of clinical activity of CART-PSMA-TGFβRDN was noted in the 2nd dose level. Two of 3 pts with 1 month follow-up demonstrated PSA decreases from baseline (1 with >95% decrease, 1 with >50% decrease). Both pts had stable disease per RECIST v1.1. A third pt with only 1 week follow-up had a 40% PSA decrease. Additional data analyses from all infused patients are ongoing and data from pts managed with modified immune toxicity management will be presented. Conclusions: Initial data indicates a unique immune toxicity profile and the potential for anti-tumor activity in mCRPC pts treated with CART-PSMA-TGFβRDN. Modified immune toxicity management could lead to identification of a manageable safety profile and therapeutically active dose. Clinical trial information: NCT04227275.

scholarly journals 121 ICAM-1-specific affinity tuned CAR T cells expressing SSTR2 for real-time imaging

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A130-A130
Author(s):  
Jingmei Hsu ◽  
Eric von Hofe ◽  
Michael Hsu ◽  
Koen Van Besien ◽  
Thomas Fahey ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Phase I ◽  
Tumor Cells ◽  
Somatostatin Receptor ◽  
Laboratory Animals ◽  
Therapeutic Window ◽  
Car T Cells ◽  
Car T

BackgroundThe use of CAR T cells for solid tumors has a number of challenges, such as lack of tumor-specific targets, CAR T cell exhaustion, and the immunosuppressive tumor microenvironment. To address these challenges, AffyImmune has developed technologies to affinity tune and track CAR T cells in patients. The targeting moiety is affinity tuned to preferentially bind to tumor cells overexpressing the target while leaving normal cells with low basal levels untouched, thereby increasing the therapeutic window and allowing for more physiological T cell killing. The CAR T cells are designed to express SSTR2 (somatostatin receptor 2), which allows for the tracking of CAR T cells in vivo via PET/CT scan using FDA-approved DOTATATE.MethodsAIC100 was generated by affinity tuning the I-domain of LFA-1, the physiological ligand to ICAM-1. Various mutants with 106-fold difference in affinity were evaluated for affinity. This allowed structure activity relationships to be conducted using CAR T cells expressing the various affinity mutants against targets with varying antigen densities. The variant with micromolar affinity was clearly the most effective in non-clinical animal models. AIC100 is currently being evaluated to assess safety, CAR T expansion, tumor localization, and preliminary activity in patients with advanced thyroid cancer in a phase I study (NCT04420754). Our study uses a modified toxicity probability interval design with three dosage groups of 10 x 106, 100 x 106, and 500 x 106 cells.ResultsPreclinical studies demonstrated greater in vivo anti-tumor activity and safety with lower affinity CAR T cells. A single dose of AIC100 resulted in tumor elimination and significantly improved survival of animals. AIC100 activity was confirmed in other high ICAM-1 tumor models including breast, gastric, and multiple myeloma. In a Phase I patient given 10-million CAR T cells, near synchronous imaging of FDG and DOTATATE revealed preliminary evidence of transient CAR T expansion and tumor reduction at multiple tumor lesions, with the peak of CAR T density coinciding with the spike in CAR T numbers in blood.ConclusionsWe have developed affinity tuned CAR T cells designed to selectively target ICAM-1 overexpressing tumor cells and to spatiotemporally image CAR T cells. Near-synchronous FDG and DOTATATE scans will enhance patient safety by early detection of off-tumor CAR T activity and validation of tumor response. We anticipate that our ‘tune and track’ technology will be widely applicable to developing potent yet safe CAR T cells against hard-to-treat solid cancers.Trial RegistrationNCT04420754Ethics ApprovalIRB number19-12021154IACUC (animal welfare): All animal experiments were performed in accordance with the National Institute of Health’s Guide for the Care and Use of Laboratory Animals. Animal handling protocols were approved by the Institutional Laboratory Animal Use and Care Committee of Weill Cornell Medicine (Permit Number: 2012–0063).

scholarly journals 548 Phase 2 study of FLX475 in combination with ipilimumab in advanced melanoma

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A578-A578
Author(s):  
Rakesh Goyal ◽  
Nicole Nasrah ◽  
Dan Johnson ◽  
William Ho
Keyword(s):  
Clinical Trial ◽  
T Cells ◽  
Antitumor Activity ◽  
Regulatory T Cells ◽  
Response Rate ◽  
Advanced Melanoma ◽  
Phase 2 ◽  
Car T Cells ◽  
Phase 2 Study ◽  
Car T

BackgroundRegulatory T cells (Treg) can dampen antitumor immune responses in the tumor microenvironment (TME) and have been shown to correlate with poor clinical outcome. Translational studies have demonstrated an accumulation of Treg in tumors after treatment with immunotherapies including CAR-T cells and anti-CTLA-4, which could potentially reflect a mechanism of adaptive immune resistance.1–2 CCR4, the receptor for the chemokines CCL17 and CCL22, is the predominant chemokine receptor on human Treg and is responsible for the migration and accumulation of Treg in the TME. Preclinical studies with orally available CCR4 antagonists have demonstrated potent inhibition of Treg migration into tumors, an increase in the intratumoral Teff/Treg ratio, and antitumor efficacy as a single agent and in combination with checkpoint inhibitors, including anti-CTLA-4.3 In a first-in-human trial conducted in healthy volunteers, the oral CCR4 antagonist FLX475 was demonstrated to be well tolerated with outstanding pharmacokinetic and pharmacodynamic properties.4 An ongoing Phase 1/2 clinical trial of FLX475 is examining the safety and preliminary antitumor activity of FLX475 as monotherapy and in combination with pembrolizumab in subjects with several types of advanced cancer.5 Given the preclinical data demonstrating a significant enhancement of the antitumor activity of anti-CTLA-4 when combined with FLX475, a Phase 2 study investigating the combination of FLX475 and ipilimumab is now being conducted in subjects with advanced melanoma.MethodsThis clinical trial is a Phase 2, multicenter, open-label, single-arm study to determine the antitumor activity of FLX475 in combination with ipilimumab in subjects with advanced melanoma previously treated with an anti-PD-1 or anti-PD-L1 agent. The primary objectives of the study are to evaluate objective response rate, and the safety and tolerability of this combination. The study will first examine the safety of the combination of the 100 mg PO QD recommended Phase 2 dose of FLX475 and the approved 3 mg/kg IV Q3W dose of ipilimumab as part of a safety run-in phase, prior to examining the degree of antitumor activity in approximately 20 subjects. Evidence of an overall response rate (ORR) notably greater than the expected ORR of ipilimumab monotherapy alone in such subjects, which has been shown to be approximately 14%,6 would provide preliminary clinical evidence in support of the clinical hypothesis that CCR4 blockade by FLX475 can significantly enhance the antitumor activity of an anti-CTLA-4 checkpoint inhibitor.Trial RegistrationClinicalTrials.gov Identifier: NCT04894994ReferencesO’Rourke D, Nasrallah M, Desai A, Melenhorst J, Mansfield K, Morrissette J, Martinez-Lage M, Brem S, Maloney E, Shen A, Isaacs R, Mohan S, Plesa G, Lacey S, Navenot J, Zheng Z, Levine B, Okada H, June C, Brogdon J, Maus M. A single dose of peripherally infused EGFRvIII-directed CAR T cells mediates antigen loss and induces adaptive resistance in patients with recurrent glioblastoma. Sci Transl Med 2017;9:eaaa0984. doi: 10.1126/scitranslmed.aaa0984.Sharma A, Subudhi S, Blando J, Vence L, Wargo J, Allison JP, Ribas A, Sharma P. Anti-CTLA-4 immunotherapy does not deplete FOXP3+ regulatory T cells (Tregs) in human cancers-Response. Clin Cancer Res 2019;25:1233–1238.Marshall L, Marubayashi S, Jorapur A, Jacobson S, Zibinsky M, Robles O, Hu D, Jackson J, Pookot D, Sanchez J, Brovarney M, Wadsworth A, Chian D, Wustrow D, Kassner P, Cutler G, Wong B, Brockstedt D, Talay O. Tumors establish resistance to immunotherapy by regulating Treg recruitment via CCR4. J Immunother Cancer 2020;8:e000764.van Marle S, van Hoogdalem E, Johnson D, Okal A, Kassner P, Wustrow D, Ho W, Smith S. Pharmacokinetics, pharmacodynamics, and safety of FLX475, an orally-available, potent, and selective small-molecule antagonist of CCR4, in healthy volunteers. J Immunother Cancer 2018; 6(Suppl 1):P484(SITC 2018).Powderly J, Chmielowski B, Brahmer J, Piha-Paul S, Bowyer S, LoRusso P, Catenacci D, Wu C, Barve M, Chisamore M, Nasrah N, Johnson D, Ho W. Phase I/II dose-escalation and expansion study of FLX475 alone and in combination with pembrolizumab in advanced cancer. Journal of Clinical Oncology 2020;38(15_suppl): TPS3163 (ASCO 2020).Long G, Mortier L, Schachter J, Middleton M, Neyns B, Sznol M, Zhou H, Ebbinghaus S, Ibrahim N, Arance A, Ribas A, Blank C and Robert C. Society for Melanoma Research 2016 Congress. Pigment Cell & Melanoma Research 2017;30:76–156.Ethics ApprovalThis study has been approved by the Institutional Review Board at each investigational site.

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