Unum Therapeutics Research Articles

LBA45 - Health-related quality of life (HRQoL) impact of pembrolizumab (P) versus chemotherapy (C) as first-line (1L) treatment in PD-L1–positive advanced gastric or gastroesophageal junction (G/GEJ) adenocarcinoma

LBA45 - Health-related quality of life (HRQoL) impact of pembrolizumab (P) versus chemotherapy (C) as first-line (1L) treatment in PD-L1–positive advanced gastric or gastroesophageal junction (G/GEJ) adenocarcinoma

LBA44 - Pembrolizumab with or without chemotherapy vs chemotherapy in patients with advanced G/GEJ cancer (GC) including outcomes according to Microsatellite Instability-High (MSI-H) status in KEYNOTE-062

LBA44 - Pembrolizumab with or without chemotherapy vs chemotherapy in patients with advanced G/GEJ cancer (GC) including outcomes according to Microsatellite Instability-High (MSI-H) status in KEYNOTE-062

A Phase 1 Study of Two Investigational Agents, ACTR087, an Autologous T Cell Product Expressing an Antibody-Coupled T Cell Receptor, in Combination with SEA-BCMA, a Novel Non-Fucosylated Monoclonal Antibody, in Subjects with Relapsed or Refractory Multiple Myeloma

Background: B cell maturation antigen (BCMA) has recently emerged as a promising candidate antigen for therapeutic targeting in multiple myeloma (MM), with several targeted agents in clinical studies including antibody-drug conjugates and bispecific T cell engagers as well as CAR T cells. The Antibody-Coupled T cell Receptor (ACTR) platform is a universal, engineered autologous T cell therapy developed to mediate anti-tumor activity in combination with tumor-targeting antibodies. The ACTR construct is composed of the ectodomain of CD16 fused to intracellular co-stimulatory and CD3ζ signaling domains (Kudo et al., Cancer Res. 2014), which allow ACTR T cells to exert antibody-dependent cell-mediated cytotoxicity, a function otherwise physiologically limited to CD16-expressing natural killer cells and macrophages.ACTR087 expresses a 4-1BB-containing receptor and has been evaluated in combination with rituximab in subjects with relapsed or refractory (R/R) CD20+ B cell lymphoma as previously reported (Akard et al., Blood 2017). SEA-BCMA is a novel, humanized non-fucosylated anti-BCMA IgG1 antibody that has been demonstrated pre-clinically to bind to ACTR087 T cells to mediate ACTR T cell activation, cytotoxicity, cytokine release, and proliferation in the presence of BCMA-expressing MM cell lines. These functional activities were demonstrated to be BCMA-specific and SEA-BCMA dose-dependent (Cheema et al., AACR 2017). Here we present preliminary findings from the first 2 single-subject cohorts of the ATTCK-17-01 study (NCT03266692), an ongoing Phase 1 study of ACTR087 in combination with the first-in-human administration of SEA-BCMA.Methods: ATTCK-17-01 is a multicenter, Phase 1, dose-escalation study of ACTR087 in combination with SEA-BCMA. The primary objectives are to characterize the safety and to determine the recommended Phase 2 dose of ACTR087 in combination with SEA-BCMA in subjects with R/R MM. The secondary objectives include evaluation of anti-myeloma activity, ACTR T cell persistence, cytokines, and SEA-BCMA pharmacokinetics (PK); exploratory objectives include the anti-myeloma activity of SEA-BCMA alone. Subjects must have measurable disease and must have received at least 3 prior lines of therapy including treatment with a proteasome inhibitor and an immunomodulatory agent, and hematopoietic stem cell transplant (HSCT) for HSCT-eligible subjects. BCMA expression on MM cells was not a condition of eligibility. Dose escalation of the 2 investigational agents, ACTR087 and SEA-BCMA, is determined according to adaptive design principles.After study enrollment and leukapheresis, subjects receive SEA-BCMA by IV infusion once every 3 weeks until disease progression or treatment discontinuation. After the third dose of SEA-BCMA and lymphodepleting chemotherapy (cyclophosphamide 300 mg/m2 and fludarabine 30 mg/m2, each daily for 3 days), subjects receive a single dose of ACTR087.Results: Two subjects enrolled and received ACTR087 at the first dose level in combination with the first 2 dose levels of SEA-BCMA. First-in-human dosing of SEA-BCMA was well tolerated, with no reported SEA-BCMA-related adverse events (AEs) or dose-limiting toxicities (DLTs).Following ACTR087 infusion, ACTR+ T cells were detectable in the peripheral blood and demonstrated expansion post-infusion. No DLTs were observed with the combination of ACTR087 and SEA-BCMA in the first 2 cohorts. Grade 3 or higher treatment-emergent AEs experienced by at least 1 subject, regardless of causality assessment, include cytopenias, increased ALT, and bone pain.Conclusions: ACTR087 in combination with SEA-BCMA was well tolerated in the first 2 subjects treated, with no DLTs or AEs leading to treatment discontinuation. These results support the continued dose escalation of ACTR087 in combination with SEA-BCMA. Enrollment in Cohort 3 is ongoing. Updated data, including SEA-BCMA PK, biomarkers, and preliminary Cohort 3 data, will be presented. DisclosuresHolmes:Unum: Research Funding; Seattle Genetics: Research Funding, Speakers Bureau; Novartis: Research Funding; Genentech: Research Funding; Celgene: Research Funding; Rigel: Consultancy; Gilead: Consultancy, Research Funding, Speakers Bureau; Bayer: Consultancy. Hari:Kite Pharma: Consultancy, Honoraria; Janssen: Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Amgen Inc.: Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Spectrum: Consultancy, Research Funding; Sanofi: Honoraria, Research Funding. Sachs:Unum Therapeutics Inc.: Employment. Exter:Unum Therapeutics Inc.: Employment. Ranger:Unum Therapeutics Inc.: Employment. Cheema:Unum Therapeutics Inc.: Employment. Sienczylo:Unum Therapeutics Inc.: Employment. O'Meara:Seattle Genetics: Employment, Equity Ownership. Sussman:Seattle Genetics: Employment. Akard:Gilead: Speakers Bureau; Celgene: Speakers Bureau; Takeda: Speakers Bureau; Novartis: Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau.

Preliminary Clinical Results of a Phase 1 Study Evaluating the Safety and Anti-Tumor Activity of ACTR707 in Combination with Rituximab in Subjects with Relapsed or Refractory CD20+ B-Cell Lymphoma

Preliminary Clinical Results of a Phase 1 Study Evaluating the Safety and Anti-Tumor Activity of ACTR707 in Combination with Rituximab in Subjects with Relapsed or Refractory CD20+ B-Cell Lymphoma

Senescent CD8+ T Cells in Myeloma Patients: Implications for Cellular Therapies

▪Background: For autologous engineered T cell therapies such as CAR-T cells, the characteristics of the input donor-derived T cells impact the final T cell product. Early less-experienced T cells are thought to generate a T cell product with optimal functions whereas, terminally differentiated T cells, displaying features of cellular senescence, are unlikely to generate an ineffective product. An increase in senescence within the CD8+ T cell population has been described in multiple myeloma (MM) (Leukemia 2016;30:1716). To better understand the challenges that may be encountered in the production of engineered T cells in MM, we evaluated the overall T cell frequency and features of senescence in the CD8+ T cells in the peripheral blood of 14 MM patients. For those patients who underwent stem cell mobilization (n = 11) we assessed the impact of this procedure on the characteristics of the T cells collected.Methods: Peripheral blood samples were collected during treatment from patients in steady-state. Patients who subsequently underwent stem cell mobilization (G-CSF/plerixafor or Cyclophosphamide) as part of their clinical care and provided a second blood sample on the day of stem cell collection (mobilized sample).PBMCs were isolated and characterized by flow cytometry using the BD ACCURI C6 flow cytometer. Staining of surface antigens was performed by using fluorescently labeled CD3, CD8, CD28, CD57, and KLRG. Senescent T cells were defined as CD3+/CD8+CD28-/CD57+, and also as CD28-/KLRG+. Statistical analyses were performed with MedCalc.Summary of Results: Steady-state samples were collected from 14 MM patients (10M, 4F) with a median age of 66.5 years (range, 52-82) and a median time from diagnosis of 7.5 months (3-72). All patients had been treated with a proteasome inhibitor, an IMiD, and dexamethasone, and 4 were receiving daratumumab. At the time of sample collection, disease response was variable with 5 PR, 7 VPGR, 1 CR, and 1 refractory disease.In the steady state PBMC, CD3+ T cells were 49.1% and CD3+/CD8+ 5.1%. Median numbers of CD28-/CD57+ and CD28-/KLRG+ T cells within the CD8+ population were 24.1% (2.5-74.4) and 31% (2.9-73%) respectively. Two subgroups of MM patients were observed. Four patients had a significantly increased frequency of senescence within the CD8+ T cells (53-74% CD28-) and 10 had a much lower frequency of senescence (2.5%-25.9%). The group with elevated senescence within the CD8+ T cells included the oldest patient in the cohort (82 years), the patient with the longest duration of disease (6 years), a heavily pre-treated patient on daratumumab with severe lymphopenia, and a patient whose myeloma was a post-transplant lymphoproliferative disorder occurring a year after heart transplant on chronic immunosuppression with tacrolimus and prednisone.Following mobilization, the percentage of T cells within the PBMCs dropped significantly from 49.1% to 8.3%. Mobilization particularly impacted the CD8+ T cell population which dropped from a median 5.4% of PBMCs in the steady-state sample to 0.8%. In the paired samples, we did not observe a consistent impact on frequency of CD28- or CD57+ (senescent) cells within the CD8+ T cells (19.1% vs 21.1%).Conclusions: A subset of MM patients exhibited a significant increase in markers of senescence within the peripheral CD8+ T cells. Older patients, those on chronic immunosuppression, and those treated for an extended time appeared to be at increased risk. T cells from such patients may be suboptimal for manufacture of engineered T cell therapies. Further, stem cell mobilization resulted in a significant decrease in T cell frequency, particularly in CD8+ T cells although senescence markers were not consistently changed. Thus, mobilized blood collections may not be optimal starting material either. DisclosuresLee:Unum Therapeutics: Research Funding. Ma:Tufts Medical Center: Patents & Royalties: Patent: 9593332.

2-Year Follow-up and High-Risk Subset Analysis of Zuma-1, the Pivotal Study of Axicabtagene Ciloleucel (Axi-Cel) in Patients with Refractory Large B Cell Lymphoma

2-Year Follow-up and High-Risk Subset Analysis of Zuma-1, the Pivotal Study of Axicabtagene Ciloleucel (Axi-Cel) in Patients with Refractory Large B Cell Lymphoma

Outcomes, Causes of Discontinuation and Mutation Profile of Patients with Mantle Cell Lymphoma Who Progressed on Acalabrutinib

Introduction: Acalabrutinib is a Bruton tyrosine kinase (BTK) inhibitor approved for treatment of relapsed patients (pts) with mantle cell lymphoma. We have reported previously that ibrutinib refractory MCL pts have poor survival. However, outcomes, causes of discontinuation, management and the genomic landscape of MCL in pts who discontinued acalabrutinib are rarely reported. Method: We reviewed charts from all MCL pts treated with single agent acalabrutinib (n=28) in the relapsed setting and identified 15 pts who discontinued acalabrutinib and who are described in this analysis. Outcome after discontinuing acalabrutinib is reported. Whole-exome sequencing (WES) with SureSelect Human All Exon V6 was performed on 10 tumor specimens and 5 matched germline samples collected from 9 pts whose MCL progressed on acalabrutinib; among these pts 4 tumors were collected at baseline and 6 were collected after disease progression. One patient had sufficient DNAs available for both time points (baseline and progression). Results: The median duration on treatment with acalabrutinib was 6.5 months (1 to 29 months) and the median number of cycles of acalabrutinib treatment was 6 (range, 1-30). Seven pts had complete remission (CR) as their best response on acalabrutinib, 5 were primary refractory and 3 achieved partial remission. In 12 pts (80%) acalabrutinib was discontinued due to disease progression (2 pts transformed from classic to blastoid and pleomorphic type at progression) and 3 pts were discontinued due to intolerance (one for fatigue and idiopathic encephalopathy, one due to unrelated severe aortic stenosis and another for cytopenias secondary to therapy related myelodysplasia; all three pts were in CR). Nine pts had classic and 3 pts each had blastoid or pleomorphic features before starting acalabrutinib. Overall, median Ki-67 expression was 50% (range, 5-100) and all pts had high a MIPI score. The median number of prior treatments was 1 (range, 1-3); all chemo-immunotherapy (10 pts were previously treated with rituximab-hyper-CVAD) and none with ibrutinib. Two pts who transformed on acalabrutinib received acalabrutinib for a median duration of 12 months (range, 8-16.5). Median follow up after discontinuation was 27 months and the median survival was 25 months (26 months for progression and 1.5 months for intolerance; p Recurrently mutated genes in these tumors included ATM (6/10; 60%), TP53 (4/10; 40%), KMT2C (3/10), MYCN (2/10), NOTCH1 (2/10), NOTCH3 (2/10), and MEF2B (2/10) (Fig. 1B). We did not detect any mutation or copy number alterations in BTK, PLCG2, TRAF2/3 and MYD88 that have been reported previously to be associated with ibrutinib resistance. Compared to tumors at baseline, ATM was mutated at a higher frequency in samples at progression (67% vs. 50%; p=NS). To investigate the mutation evolution on acalabrutinib treatment, mutation profiles, particularly the mutation variant allelic fractions (VAFs), were compared between the baseline and progression samples from pt-1 (Fig. 1C). Mutation of MYCN, MEF2B, ATM, and NOTCH1 were identified in both tumors at similar VAFs, whereas mutation of CARD11 (two mutations), NLRC5 and B2M were detected only at progression. In pt-1, both the NLRC5 and β2M mutations acquired at disease progression were truncating, suggesting loss-of-function alterations. Copy number analysis reveals frequent whole-genome doubling and intensive copy number alterations in all tumors, including recurrent losses of chromosome 9p, 17p, and chromosome 13, indicating chromosomal instability as a driver of disease progression. Conclusion: Patients who progress on acalabrutinib have a poor outcome, and newer therapies are required for their treatment. In this small cohort, we observed non-BTK mutations associated with acalabrutinib resistance and disease progression. Disclosures Nastoupil:Genentech: Honoraria, Research Funding; TG Therappeutics: Research Funding; Spectrum: Honoraria; Gilead: Honoraria; Merck: Honoraria, Research Funding; Janssen: Research Funding; Celgene: Honoraria, Research Funding; Karus: Research Funding; Novartis: Honoraria; Juno: Honoraria. Neelapu:Celgene: Consultancy, Membership on an entity9s Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; Poseida: Research Funding; Merck: Consultancy, Membership on an entity9s Board of Directors or advisory committees, Research Funding; Acerta: Research Funding; Karus: Research Funding; Bristol-Myers Squibb: Research Funding; Unum Therapeutics: Membership on an entity9s Board of Directors or advisory committees; Kite/Gilead: Consultancy, Membership on an entity9s Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity9s Board of Directors or advisory committees. Fowler:Janssen: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding. Wang:Acerta Pharma: Honoraria, Research Funding; MoreHealth: Consultancy; AstraZeneca: Consultancy, Research Funding; Kite Pharma: Research Funding; Celgene: Honoraria, Membership on an entity9s Board of Directors or advisory committees, Research Funding; Dava Oncology: Honoraria; Juno: Research Funding; Pharmacyclics: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity9s Board of Directors or advisory committees, Research Funding; Novartis: Research Funding.

Evaluating Hematologist's Knowledge of CAR T-Cell Therapy in Hematologic Malignancies

Background: The objective of this study was to assess current clinical practices of hematologist/oncologist (hem/onc) specialists related to chimeric antigen receptor (CAR) T-cell therapy in hematologic malignancies, in order to identify knowledge, competency, and practice gaps and barriers to optimal care.Methods: A continuing medical education (CME)-certified clinical practice assessment consisting of 25 multiple choice questions was developed to measure knowledge, skills, attitudes, and competence of hem/onc specialists regarding CAR T-cell therapy. The survey instrument was made available online to physicians without monetary compensation or charge. Respondent confidentiality was maintained, and responses were de-identified and aggregated prior to analyses. The activity launched on December 22, 2017 with global distribution, and participant responses are still being collected at the time of abstract submission.Results: At the time of this report there are 192 hem/onc activity participants, collection is on-going. Demographics are listed in Table 1 and levels of confidence and barriers to incorporating CAR T-cell therapy are listed in Table 2.•Foundational Knowledge•Sub-optimal knowledge was demonstrated in the area of CAR components, dosing, and FDA-approved indications.•Over half (61%) could not correctly identify the components of a CAR construct (antigen-specific domain and the signaling domain).•Almost half (45%) of the participants did not recognize that currently approved CAR T-cell therapies are dosed as a single infusion.•25% demonstrated inaccurate knowledge by recommending patients wait 4 weeks after CAR T-cell infusion before driving.•Over half (62%) of participants could not identify the FDA-approved indication for axicabtagene ciloleucel.Knowledge of Clinical Trial Data•Very low awareness of efficacy data seen with various CAR T-cell products used to treat R/R B-cell ALL (ELIANA trial), R/R DLBCL (ZUMA-1, JULIET, TRANSCEND trials).•Only 32% identified the correct CR/CRi rate seen with tisagenlecleucel in the ELIANA trial.•Only 25% correctly identified the CR rate seen with axicabtagene ciloleucel in the ZUMA-1 trial.•Only 32% demonstrated knowledge of the 6-month DFS rate for patients in the JULIET trial that had a CR at 3 months.•Only 25% identified the association between the dose of JCAR017 and response rates from the TRANSCEND trial.Knowledge and Competence Managing Adverse Events•Lack of competence recognizing and treating CAR T-cell associated adverse events such as cytokine release syndrome (CRS) and neurotoxicity.•Almost half (44%) could not identify signs of CRS associated with CAR T-cell therapy and 43% lack knowledge that elevated serum C-reactive protein (CRP) is associated with the highest level of CRS (in patients with lymphoma receiving axicabtagene ciloleucel).•41% could not identify that the mechanism of tocilizumab is to block IL-6 signaling.•Over a third (35%) were unable to identify signs/symptoms/causes of neurotoxicity associated with CAR T-cell therapy.•More than half of the learners (54%) could not identify the appropriate role of corticosteroid therapy after CAR T-cell administration in managing CRS and neurotoxicity.Conclusions: This activity found knowledge and competence deficits for hem/onc practitioners related to using CAR T-cell therapy for the treatment of patients with hematologic malignancies. Additionally, the activity demonstrated large gaps in confidence discussing CAR T-cell therapy with patients/families and managing adverse events. There is sub-optimal awareness of CAR T-cell foundational knowledge, clinical trial data, and recognition of common therapy related adverse events and management strategies. Additional education is needed to improve the knowledge, competence, and confidence of academic and community hem/onc specialists who care for patients with hematologic malignancies receiving CAR T-cell therapy as well as strategies for integrating novel agents into clinical practice. [Display omitted] DisclosuresNeelapu:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; Poseida: Research Funding; Merck: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta: Research Funding; Karus: Research Funding; Bristol-Myers Squibb: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Unum Therapeutics: Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Clinical and Genomic Characteristics in De Novo Blastoid/Pleomorphic (dnMCL) and Transformed Blastoid/Pleomorphic (t-MCL) Mantle Cell Lymphoma (MCL) in the Ibrutinib Era: Comprehensive Analysis of 168 Patients

Clinical and Genomic Characteristics in De Novo Blastoid/Pleomorphic (dnMCL) and Transformed Blastoid/Pleomorphic (t-MCL) Mantle Cell Lymphoma (MCL) in the Ibrutinib Era: Comprehensive Analysis of 168 Patients

Safety and Efficacy of Ibrutinib in Combination with Rituximab and Lenalidomide in Previously Untreated Subjects with Follicular and Marginal Zone Lymphoma: An Open Label, Phase II Study

IntroductionGiven the relapsing nature of indolent non-Hodgkin lymphomas (iNHL), the prolonged natural history suggests many patients will undergo multiple lines of therapy over the course of their disease. Combination approaches with rational selection of synergistic mechanisms of action are desirable to improve outcomes and minimize overlapping toxicity. Rituximab and lenalidomide (R2) has resulted in favorable efficacy and manageable toxicity in phase II and III studies (Fowler et al, Lanc Oncol 2014; Fowler et al, ASCO abstract 2018) in untreated iNHL. Ibrutinib, a BTK inhibitor and active B-cell receptor signaling pathway inhibitor, is an attractive agent to build upon R2 given the therapeutic activity in the microenvironment via enhanced T cell activation and function, reduction in inflammatory cytokines, and diminished interaction with macrophages (Niemann et al, Clin Can Res 2015). We hypothesized that the addition of ibrutinib to R2 (IR2) would result in enhanced efficacy; the concern from the Phase I study was the potential for excess grade 3 rash (Ujjani et al, Blood 2016). In an attempt to reduce the incidence of grade 3 rash observed in the phase 1 study, an alteration in the cycle 1 dose of lenalidomide was done to assess the efficacy and safety of IR2 in untreated follicular (FL) and marginal zone lymphoma (MZL) in an open-label phase II, single center study.MethodsIn this phase II study, adults with untreated stage II, III, or IV FL (grade 1, 2, or 3a) or MZL, who were in need of therapy, received an initial cycle of lenalidomide 15mg/day (days 1-21 of a 28 day cycle), ibrutinib 560mg/day, and 4 weekly doses of rituximab (375mg/m2). For cycles 2-12, patients received 20mg of lenalidomide on days 1-21, 560mg of ibrutinib daily, and rituximab (375mg/m2) on day 1 of each cycle. The primary endpoint was progression-free survival (PFS) at 2 years. Secondary endpoints include: complete response (CR), partial response (PR), overall response (ORR), duration of response (DOR) and overall survival (OS).ResultsForty-eight patients with FL (N=38) and MZL (N=10; nodal MZL N=4; splenic ZML N=3; MALT N=3) were enrolled. Median age was 60 years (range 37-81), 67% were male (N=32), 3 (6%) had stage II disease, 12 (25%) stage III, and the remainder had stage IV disease (69%). With a median follow up of 19 months, the estimated 2 year PFS rate was 76% (95% CI: 60-96%). Among FL patients, the ORR according to Lugano criteria was 97%, with a CR rate of 78%. Among MZL patients, the ORR was 80% with a CR rate of 60%.No deaths have been observed to date. Seven (15%) subjects discontinued therapy due to treatment related adverse events (AEs), 3 due to recurrent grade 3 rash, 2 due to pneumonitis (1 grade 2, 1 grade 3), 1 due to pneumonia (grade 3), and 1 due to ventricular arrhythmia (grade 4). The most common grade ≥3 AEs were rash (46%), neutropenia (15%), and diarrhea (13%). The majority of patients with grade 3 rash were managed with interruption in study drugs and antihistamines with successful re-challenge. The most common grade 2 AEs included fatigue (23%), diarrhea (15%), myalgias (17%), rash and edema (each 10%). One patient experienced atrial fibrillation (grade 2) and 1 had an upper GI bleed (grade 3); both successfully resumed treatment without dose reduction. Correlative and minimal residual disease studies are currently underway and will be presented at the meeting.ConclusionsIbrutinib in combination with rituximab and lenalidomide for untreated FL and MZL was associated with promising efficacy. The toxicity profile was manageable. Modification of lenalidomide dose did not significantly impact the incidence of grade 3 or higher rash. Biomarkers are underway to identify patients most likely to benefit from triplet therapy. DisclosuresNastoupil:Merck: Honoraria, Research Funding; Janssen: Research Funding; TG Therappeutics: Research Funding; Celgene: Honoraria, Research Funding; Gilead: Honoraria; Novartis: Honoraria; Spectrum: Honoraria; Genentech: Honoraria, Research Funding; Karus: Research Funding; Juno: Honoraria. Westin:Celgen: Membership on an entity's Board of Directors or advisory committees; Apotex: Membership on an entity's Board of Directors or advisory committees; Novartis Pharmaceuticals Corporation: Membership on an entity's Board of Directors or advisory committees; Kite Pharma: Membership on an entity's Board of Directors or advisory committees. Samaniego:ADC Therapeutics: Research Funding. Neelapu:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; Poseida: Research Funding; Merck: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta: Research Funding; Karus: Research Funding; Bristol-Myers Squibb: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Unum Therapeutics: Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Fowler:Janssen: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding.

ACTR087, Autologous T Lymphocytes Expressing Antibody Coupled T-Cell Receptors (ACTR), Induces Complete Responses in Patients with Relapsed or Refractory CD20-Positive B-Cell Lymphoma, in Combination with Rituximab

Background: Autologous T cells engineered to express the universal ACTR chimeric receptor kill tumors through interactions with tumor-targeting antibodies [Kudo, Cancer Res. 2014]. Preclinical findings with ACTR+ T cells, which bind immunoglobulin Fc via CD16V158 and signal via CD3ζ and 4-1BB (ACTR087), demonstrate markedly enhanced target- and antibody-specific tumor cell cytotoxicity, as evidenced by CD20+ B cell lymphoma killing in combination with rituximab, compared with rituximab alone. Preclinical data also demonstrate rituximab dose-dependent effects in combination with ACTR087, suggesting that the therapeutic index of ACTR087 in combination with rituximab may be affected by rituximab dose or schedule and present an advantage over chimeric antigen receptor (CAR) T cell therapies [Huet H, Blood 2016]. Study UT-201501 (ATTCK-20-2) is the first clinical trial of ACTR087 in combination with rituximab in patients with relapsed or refractory CD20+ B cell lymphoma previously treated with rituximab (NCT02776813). We report data from the 7 patients treated with ACTR087 in the first dose level of the ATTCK-20-2 study.Methods: This is a multicenter Phase 1 dose escalation study. The primary objective is to evaluate the safety of the combination of ACTR087 and rituximab, and the key secondary objective is to evaluate antitumor efficacy. Exploratory objectives include measurement of ACTR T cell persistence, cytokines, and rituximab pharmacokinetics. Eligible patients must have histologically confirmed relapsed/refractory aggressive CD20+ B cell lymphoma of DLBCL, MCL, PBMCL, Gr3b FL, or transformed FL subtype and have received prior anti-CD20 mAb in combination with anthracycline-containing chemotherapy. In the first dose level, patients received lymphodepleting chemotherapy (cyclophosphamide 500 mg/m2 and fludarabine 30 mg/m2) for 3 days, followed by rituximab (375 mg/m2) and ACTR087 (0.5x106 ACTR+ T cells/kg). Up to 7 additional doses of rituximab are then administered, one dose every 3 weeks in the absence of disease progression.Results: Seven patients received ACTR087 in combination with rituximab at the first dose level. Median age was 64 years (range: 36-71), 57.1% were male, all had ECOG PS 1, 86% were treated with ≥ 3 lines of prior therapy, and 86% were refractory to the immediate prior therapy. ACTR087 was successfully manufactured for all subjects. ACTR+ T cells were detectable in the peripheral blood and demonstrated expansion post-infusion. One patient had a dose-limiting toxicity of grade 4 thrombocytopenia for > 14 days that later resolved. At the first dose level, there were no SAEs or deaths related to ACTR087 and no AEs of special interest, including cytokine-release syndrome, neurotoxicity, or autoimmune events. Cytopenias were the most common ≥ grade 3 AEs (neutropenia n=7, leukopenia n=5). Rituximab pharmacokinetics were not affected by ACTR087 administration. Independently-confirmed objective responses were observed in patients evaluable for response (n=6), including 2 ongoing complete responses (CR) and 1 partial response (PR). One of the CRs continues 6+ months after a single dose of ACTR087.Conclusions:In the first dose level studied in patients with relapsed/refractory aggressive CD20+ B cell lymphoma, ACTR087 in combination with rituximab induced complete responses with no serious AEs, AEs leading to treatment discontinuation, cytokine-release syndrome, or neurotoxicity. ACTR+ T cells were detectable in all patients and ACTR+ T cells persisted in the presence of continued rituximab administration. These results support the continued dose escalation of ACTR087 in combination with rituximab; dose level 2 enrollment is ongoing and updated data, including correlative biomarkers, will be presented. DisclosuresJaglowski:Novartis Pharmaceuticals Corporation: Consultancy, Research Funding; Kite Pharma: Consultancy, Research Funding; Unum Therapeutics: Research Funding; Pharmacyclics Inc: Research Funding. McKinney:Kite Pharma: Other: advisory comittee. Vasconcelles:Unum Therapeutics Inc: Employment. Huet:Unum Therapeutics Inc: Employment. Ettenberg:Unum Therapeutics Inc.: Employment. Ranger:Unum Therapeutics Inc: Employment. Abramson:Seattle Genetics: Consultancy; Genentech: Consultancy; Gilead: Consultancy; Kite Pharma: Consultancy; Abbvie: Consultancy; Celgene: Consultancy; LAM Therapeutics: Research Funding; Novartis: Consultancy.

Enhancing the Efficacy of CAR T Cells

The impressive response rates of chimeric antigen receptor (CAR) modified T cells in B-ALL and high grade B cell lymphomas illustrate their remarkable capacity to kill chemoresistant cancer. However, much work remains to be done if CAR T cells are to cure a high fraction of patients with B cell malignancies and if this potency is to be extended to other chemoresistant cancers. Experience in B cell malignancies has identified primary mechanisms of resistance to CAR T cells as antigen escape and T cell failure, which are generally mutually exclusive, such that antigen escape occurs in cases where CAR T cells persist whereas antigen positive recurrence is associated with disappearance of CAR T cells. A significant factor driving antigen escape is a requirement for high antigen density for CAR T cell function. Unlike natural T cells which are activated by low antigen density (e.g. ~10 peptides/cell), CAR T cells require high antigen density for activation, estimated to be ~10,000 antigens/cell. This is most well illustrated by experience with the CD22-CARs for B-ALL. CD22-CARs induce high response rates in both CD19+ and CD19neg/lo B-ALL, however this is followed by a significant rate of relapse associated with expression of CD22lo B-ALL. The basis for the CAR T cell requirement for high antigen density remains incompletely understood and efforts are underway to lower the antigen density required for CAR T cell activation. But this property could be leveraged to provide a therapeutic window for targeting antigens with low level expression on normal tissues, which may be useful for extending the efficacy of CAR T cells to solid tumors. Furthermore, acknowledgement of the CAR requirement for high antigen density as well as the general property of tumor heterogeneity leads to the prediction that monospecific CAR T cells are unlikely to eradicate most cancers. We have therefore focused efforts on optimizing approaches to develop bispecific CAR T cells and are currently testing bivalent, bispecific CD19/22-CAR T cells capable of activating in response to CD19 and/or CD22 expression. We hypothesize that simultaneous targeting of two antigens will lower the risk of antigen loss escape in B cell malignancies. The second major cause of resistance following CAR T cell therapy is T cell failure, most commonly as a result of T cell exhaustion. Current understanding of the biology of human T cell exhaustion remains incomplete. My laboratory has developed a model of "T cell exhaustion in a dish", which uses a synthetic biology model of tonically signaling CAR T cells to induce excessive TCR zeta phosphorylation and drive T cell exhaustion. We have observed that temporary cessation of TCR zeta phosphorylation using a small molecule based system to regulate CAR protein expression levels leads to remarkable rejuvenation of exhausted T cells. The rejuvenation induced via temporary cessation of zeta phosphorylation is significantly more potent than that induced by PD-1 blockade. These results suggest that regulatable CAR expression systems could prevent and/or reverse T cell exhaustion by attacking the "root cause", namely excessive or prolonged zeta phosphorylation. Disclosures Mackall: Vor Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Adapt immune: Membership on an entity's Board of Directors or advisory committees; Glaxo-Smith-Kline: Membership on an entity's Board of Directors or advisory committees; Unum Therapeutics: Membership on an entity's Board of Directors or advisory committees; Juno Therapeutics: Patents & Royalties: CD22-CAR; Bluebird Bio: Research Funding.

Patient-Reported Quality of Life (QoL) Following CTL019 Infusion in Adult Patients (pts) with Relapsed/Refractory (r/r) Diffuse Large B-Cell Lymphoma (DLBCL)

Patient-Reported Quality of Life (QoL) Following CTL019 Infusion in Adult Patients (pts) with Relapsed/Refractory (r/r) Diffuse Large B-Cell Lymphoma (DLBCL)

Targeting CD20+ Relapsed Refractory B Cell Lymphoma with ACTR087, Antibody-Coupled T-Cell Receptor (ACTR) Engineered Autologous T Cells, in Combination with Rituximab

The Antibody-Coupled T-cell Receptor (ACTR) platform is a universal engineered T cell therapy developed to mediate anti-tumor activity in combination with tumor-targeting antibodies. The ACTR construct is composed of the extracellular domain of CD16 (FCGR3A; high-affinity V158 variant) linked to CD3ζ signaling and 41BB co-stimulatory domains. ACTR-expressing T cells recognize antibodies bound to antigen on the surface of target cells, and this receptor engagement results in T cell activation, proliferation, and cytotoxic attack of target cells. Previous preclinical research has demonstrated that ACTR T cells elicit tumor cell cytotoxicity in combination with rituximab, trastuzumab, and hu14.18K322A against CD20, HER2, and GD2 expressing tumor cell lines, respectively (Kudo et al., Cancer Res 2014; 74:93-103). The safety of ACTR T cells in combination with rituximab for subjects with B-cell malignancies is currently being explored in a pilot phase 1 clinical study (ATTCK-20) sponsored by National University Hospital, Singapore. Electroporation of mRNA is being used to deliver the ACTR transgene to study subjects’ T-cells, creating a transiently active form of the therapy.In this study, we present non-clinical data supporting the first-in-human clinical trial of ACTR087, the ACTR transgene (CD16V-41BB-CD3ζ) delivered by γ-retrovirus to human T cells, in combination with rituximab in relapsed refractory B cell lymphoma (NCT02776813). In vitro data demonstrate that in the absence of rituximab or in the presence of non-targeting antibodies, no increase in cytotoxicity is observed, demonstrating that ACTR signaling is target- and antibody-specific. ACTR T cells proliferate in response to rituximab-bound lymphoma cells, but this proliferation is antibody-dependent and self-limiting in the absence of antibody. In vivo efficacy and pharmacokinetic studies further support the dependence on adequate rituximab exposure for ACTR T cell response, suggesting that ACTR T cell activity can be modulated by antibody dose and schedule, which is a potential advantage over other chimeric antigen receptor (CAR) T cell therapies.Additional in vitro studies were conducted to explore the effects of potential interventional antibody therapies used to mitigate adverse events reported for CAR-T therapies in similar patient populations. These include tocilizumab, used to treat cytokine release syndrome (CRS), and intravenous immunoglobulin (IVIG), used to treat hypogammaglobulinemia complicated by recurrent sinopulmonary infections. At therapeutically relevant doses, rituximab was able to compete with substantial excess IVIG to induce a CD20-specific ACTR T cell response. Importantly, IVIG did not induce greater cytokine release from ACTR T cells. Likewise, tocilizumab did not mediate ACTR T cell activation or cytotoxicity of IL-6R+ target cells, consistent with reports that tocilizumab is ADCC-deficient. These data illustrate an important principal of Fc receptor biology: not all IgG1 antibodies mediate ADCC despite binding to CD16, and support the considered use in the presence of ACTR T cells under certain circumstances. Taken together, these non-clinical data demonstrate the specificity and versatility of the ACTR T cell therapeutic approach to target diverse cancer antigens.The Phase 1 study (ATTCK20-2, ClinicalTrial.gov No. NCT02776813) of ACTR087 plus rituximab in subjects with relapsed or refractory CD20-positive B cell lymphoma is a multi-center, single-arm, open-label study evaluating the safety and efficacy of an autologous T-cells, culture expanded and transduced ex vivo with a γ-retrovirus containing an ACTR expression construct (CD16V-41BB-CD3ζ). Subjects who meet eligibility requirements with histologically-confirmed relapsed or refractory CD20+ B-cell lymphoma of one of the following types are eligible for the study: DLBCL, MCL, PMBCL, Gr3b-FL, TH-FL. Following a conditioning regimen with fludarabine and cyclophosphamide, and prior to ACTR087 infusion, subjects will receive rituximab at the standard IV clinical dose, 375 mg/m2. Subjects may receive up to 7 additional cycles of rituximab 375 mg/m2 at 3-week intervals and continuing as long as they show evidence of response. DisclosuresHuet:Unum Therapeutics: Employment. Judge:Unum Therapeutics: Employment. Barnitz:Unum Therapeutics: Employment. Boomer:Unum Therapeutics: Employment. McGinness:Unum Therapeutics: Employment. Shin:Unum Therapeutics: Employment. Cheema:Unum Therapeutics: Employment. Whiteman:Unum Therapeutics: Employment. Schultes:Unum Therapeutics: Employment. Ranger:Unum Therapeutics: Employment. Cao:Unum Therapeutics: Employment. Hodge:Unum Therapeutics: Employment. Vasconcelles:Unum Therapeutics: Employment. Ettenberg:Unum Therapeutics: Employment.

A First-in-Human Study of Autologous T Lymphocytes with Antibody-Dependent Cell Cytotoxicity (ADCC) in Patients with B-Cell Non-Hodgkin Lymphoma (NHL)

Recent trials in patients with B-cell malignancies have demonstrated the clinical potential of chimeric antigen receptor (CAR)-directed T cells. We developed a chimeric receptor (antibody-coupled T-cell receptor, ACTR) consisting of high affinity CD16 V158, CD8α transmembrane domain, 4-1BB and CD3ζ (Kudo et al. Cancer Res 2014). Expression of ACTR conferred ADCC capacity to T cells. In vitro and in immunodeficient mice, ACTR T cells specifically killed B-NHL and chronic lymphocytic leukemia cells tagged with the anti-CD20 antibody rituximab. Trastuzumab induced ACTR-mediated T cell killing of breast and gastric cancer cells, and anti-GD2 of neuroblastoma and osteosarcoma cells. Thus, infusion of ACTR T cells might significantly augment the anti-tumor potential of immunotherapeutic antibodies, and expand options for cell therapy of cancer.To assess the safety of this strategy and explore its efficacy, we began a pilot study in patients with relapsed/refractory CD20+ B-NHL (ATTCK20; ClinicalTrials.gov No. NCT02315118). In this first-in-human study, ACTR expression is achieved by mRNA electroporation and, hence, is transient. In Phase 1a, 3 subjects receive one dose of autologous ACTR T cells (0.5 x 106/kg) 2 days after rituximab (500 mg/m2); a second dose of ACTR T cells at 0.5 x 107/kg 28 days later is allowed if there is no toxicity and evidence of response. Interleukin-2 (IL-2) is given subcutaneously at 1 million IU/m2/d x 3 during the first week after infusion. Phase 1b plans up to 4 infusions of ACTR T cells (0.5 x 107/kg) at 10 day intervals, each preceded by rituximab at 375 mg/m2; IL-2 (as in Phase1a) is given after the first 2 infusions only.Six subjects have been enrolled to date (3 in Phase 1a, 3 in Phase 1b) and received a total of 14 ACTR T cell infusions. All had advanced CD20+ B-NHL (2 diffuse large B cell lymphoma, 2 primary mediastinal B cell lymphoma, 1 mantle cell lymphoma, and 1 mediastinal grey zone lymphoma) and had failed multiple lines of therapy. As a lymphodepleting regimen prior to the first ACTR T cell infusion, 5 of the 6 patients received fludarabine (25 mg/m2/d x 5) plus cyclophosphamide (60 mg/kg/d x 1, n=3; 900 mg/m2/d x 1, n=2); the remaining patient received bendamustine (90 mg/m2/d x 2).After leukapheresis, T cells were cultured under cGMP conditions with anti-CD3 and -CD28 antibodies, and IL-2. After 10 days, cells were electroporated with ACTR mRNA using the MaxCyte GT system. The next day, median ACTR expression in T cells, as shown by flow cytometry, was 95.8% (range, 82.8%-99.3%; n=14). With Rituximab, this produced a median cytotoxicity of 77.5% (67.6%-97.6%; n=14) against CD20+ Daudi cells at a 4:1 effector : target ratio in 4 hours. As expected, ACTR expression in vitro remained high for the first 3-4 days, declining thereafter.We met or exceeded the estimated minimum target levels of CD3+ ACTR+ cells in 13 of the 14 infused cell products. CD3+ ACTR+ cells (mostly CD8+) were detectable in peripheral blood 1 day after infusion and reached their peak on day 3-4 when they represented 0.43-11.20 (median, 1.27) cells per µL. They became undetectable after day 6, reflecting the kinetics of ACTR expression in vitro.As of July 2016, 5 of the 6 patients are evaluable, with a median follow-up of 60 weeks (range, 6-83) after the last ACTR-T cell infusion; the remaining patient has received 3 of the 4 scheduled cycles. The main toxicities were grade 3-4 cytopenias: these were observed in all patients and likely due to the lymphodepleting regimen. There was no non-hematologic toxicity, nor evidence of cytokine release syndrome. In Phase 1a, 2 patients had progressive disease (PD) and 1 had stable disease (SD) on CT scan following the first and second infusions, with PET-CT showing reduced FDG avidity and central areas of photopenia suggestive of necrosis. Of the 2 Phase 1b patients evaluable for response, 1 had PD after the third infusion and was taken off study; the other had SD 1 month after 4 ACTR-T infusions; the 2nd month assessment was interpreted as PD.The initial results of this ongoing trial using autologous T cells with transient ACTR expression are encouraging and warrant additional studies with more potent formulations of this technology. To this end, a clinical trial for patients with relapsed/refractory CD20+ B-NHL in which ACTR is permanently expressed in autologous T cells via viral vector transduction is planned (ClinicalTrials.gov No. NCT02776813). DisclosuresCampana:Unum Therapeutics: Consultancy, Equity Ownership, Patents & Royalties; Juno Therapeutics: Patents & Royalties; Nkarta Therapeutics: Consultancy, Equity Ownership, Patents & Royalties.