ALBERT

Description: We have treated a total of 30 patients with autologous T cells genetically modified to express a chimeric antigen receptor (CAR) targeting the B-cell antigen CD19; 22 of 27 evaluable patients obtained either complete remissions (CR) or partial remissions (PR). Ten patients remain in ongoing CRs of 1 to 37 months duration. The CAR was encoded by a gammaretroviral vector and included the variable regions of an anti-CD19 antibody along with CD28 and CD3-zeta moieties. The first 21 patients treated on this protocol have been reported (Kochenderfer et al. Blood 2010, Blood 2012, and Journal of Clinical Oncology 2014). To enhance the activity of the transferred CAR T cells, T-cell infusions in the previously reported patients were preceded by a chemotherapy regimen of high-dose cyclophosphamide (60-120 mg/kg) plus fludarabine. In an attempt to reduce the overall toxicity of our anti-CD19 CAR treatment protocol, we substantially reduced the doses of chemotherapy administered before CAR T-cell infusions. This abstract communicates results from 9 patients with B-cell lymphoma who received a single infusion of 1x106 anti-CD19-CAR-expressing T cells/kg bodyweight preceded by a low-dose chemotherapy regimen consisting of cyclophosphamide 300 mg/m2 and fludarabine 30 mg/m2 (Table). Each chemotherapy agent was administered daily for 3 days. Eight of the 9 treated patients had DLBCL (diffuse large B-cell lymphoma) that was refractory to chemotherapy (chemo-refractory) or that had relapsed less than 1 year after autologous stem cell transplantation (ASCT). Both of these clinical situations carry a grim prognosis, with median overall survivals of only a few months. Despite the very poor prognoses of our patients, one patient with DLBCL obtained a CR and 4 DLBCL patients obtained PRs. In some patients, PRs included resolution of large lymphoma masses. Compared to our previous experience with anti-CD19 CAR T cells preceded by high-dose chemotherapy, toxicity was reduced when CAR T cells were infused after low-dose chemotherapy. None of the 9 patients treated with low-dose chemotherapy and CAR T cells required vasopressor drugs or mechanical ventilation, although some patients did have short-term neurological toxicity. Cytopenias were mild with a mean of only 1.4 days of blood neutrophils

Description: Key Points Gene expression in TCR-engineered cells resembles that of virus-reactive cells more than native tumor antigen-reactive cells. Persisting TCR gene–engineered T cells are sensitive to PD-L1–PD-1 interaction but CD160-associated impairment is ligand-independent.

Description: We have treated 20 patients and administered 23 total T-cell infusions on a clinical trial of autologous T cells genetically modified to express a chimeric antigen receptor (CAR) targeting the B-cell antigen CD19. This is the largest reported clinical trial of anti-CD19-CAR T cells. The first 9 CAR-T-cell treatments have been reported (Kochenderfer et al. Blood 2010 and Blood 2012). This abstract communicates unreported results from 14 patients who received anti-CD19-CAR T cells produced with a new 10-day culture process. These patients did not receive exogenous interleukin-2. Of these 14 patients, 5 obtained complete remissions (CR), and 6 obtained partial remissions (PR), (see table).TablePatientAge/GenderMalignancyNumberof priortherapiesTotal cyclo-phosphamidedose(mg/kg)Number ofCAR+ T cellsinfused(X106/kg)Response(timeafter cellinfusion inmonths)156/MSMZL41205PR (20+)243/FPMBCL4605CR (19+)361/MCLL2604CR (16+)430/FPMBCL31202.5NE563/MCLL41202.5CR (10+)648/MCLL1602.5CR (7+)742/MDLBCL5602.5CR (4+)844/FPMBCL10602.5PR (6+)938/MPMBCL31202.5SD (1)1057/FLow-grade NHL4601PR (4+)1158/FDLBCL from CLL13601PR (2)1260/FDLBCL3601SD (1+)1368/MCLL4601PR (2+)1443/MDLBCL2601PR (1+) The CAR used in this work is encoded by a gammaretrovirus and incorporates the variable regions of an anti-CD19 antibody, part of CD28, and part of CD3-zeta. A mean of 70.5% of the infused T cells expressed the CAR, and the infused cells produced cytokines and degranulated in a CD19-specific manner. Because prior chemotherapy has been shown to enhance the activity of adoptively-transferred T cells, patients received cyclophosphamide (total doses shown in table) plus fludarabine (25 mg/m2 daily for 5 days) before a single infusion of anti-CD19-CAR-transduced T cells. This is the first report of successful treatment of chemotherapy-refractory primary mediastinal B-cell lymphoma (PMBCL) and diffuse large B-cell lymphoma not otherwise specified (DLBCL) with anti-CD19-CAR T cells. All of the 8 treated patients with either PMBCL or DLBCL were chemotherapy-refractory, and 5 of these 8 patients obtained either a CR or PR on this trial. We defined chemotherapy-refractory as progression or no response 1 month after the end of the most recent chemotherapy. For example, Patient 2 had PMBCL that was refractory to 3 different chemotherapy regimens and that relapsed after radiation therapy. Patient 2 obtained a CR after infusion of anti-CD19 CAR T cells and remains in CR 19 months post-infusion. Blood B-cell depletion lasting more than 3 months occurred in 3 of 3 evaluable patients. Most patients were not evaluable for B-cell depletion due to B-cell depletion by prior treatments. One patient died suddenly of unknown etiology 16 days after infusion of CAR T cells. Acute toxicities including fever, hypotension, and delirium occurred after infusion of anti-CD19-CAR T cells. The toxicities resolved in less than 3 weeks after the cell infusion and were temporally associated with elevated serum interleukin-6 and interferon gamma levels in most patients. Peak blood levels of cells containing the CAR gene ranged from 2.3% to 66.5% of blood mononuclear cells. These results demonstrate the feasibility of treating patients with chemotherapy-refractory B-cell malignancies by using autologous anti-CD19 CAR T cells. The numerous remissions obtained should encourage further development of this approach. SMZL, splenic marginal zone lymphoma; PMBCL, primary mediastinal B-cell lymphoma; CLL, chronic lymphocytic leukemia; DLBCL, diffuse large B-cell lymphoma not otherwise specified. CR, complete remission; NE, not evaluable; PR, partial remission; SD, stable disease. (+) indicates an ongoing response. Disclosures: Rosenberg: Kite Pharma: Research Funding.

Description: During an analysis of T-cell responses against human renal cell carcinoma (RCC), we identified a CD4+ T-cell line that showed TCR-mediated recognition and lysis of nearly all RCC lines regardless of MHC type. We have now elucidated the nature of the ligand for this α/β TCR, and it contains no MHC-related moiety and does not involve classic peptide processing. First, matrix metalloproteinase 14 (MMP14) expressed on RCC cells releases membrane-bound TRAIL expressed by the T cell; then, soluble TRAIL binds to its receptor DR4 (TRAIL-R1), which is expressed on tumor cells, and this TRAIL-DR4 complex is recognized by the TCR through a complementarity-determining region 3α (CDR3α)–mediated interaction. Direct and specific antigen-TCR interaction was demonstrated when the immobilized recombinant TRAIL/DR4 complex stimulated the TCR. In addition, amino acid substitutions in the CDR3α of the TCR either obliterated or enhanced target-specific recognition. This description of the molecular nature of a non-MHC target structure recognized by a naturally occurring α/β TCR not only broadens our concept of what the TCR can recognize, but also raises the question of whether such a T cell could be of clinical utility against RCC.

Description: We conducted a clinical trial to assess adoptive transfer of T cells genetically modified to express an anti-CD19 chimeric Ag receptor (CAR). Our clinical protocol consisted of chemotherapy followed by an infusion of anti–CD19-CAR–transduced T cells and a course of IL-2. Six of the 8 patients treated on our protocol obtained remissions of their advanced, progressive B-cell malignancies. Four of the 8 patients treated on the protocol had long-term depletion of normal polyclonal CD19+ B-lineage cells. Cells containing the anti-CD19 CAR gene were detected in the blood of all patients. Four of the 8 treated patients had prominent elevations in serum levels of the inflammatory cytokines IFNγ and TNF. The severity of acute toxicities experienced by the patients correlated with serum IFNγ and TNF levels. The infused anti–CD19-CAR–transduced T cells were a possible source of these inflammatory cytokines because we demonstrated peripheral blood T cells that produced TNF and IFNγ ex vivo in a CD19-specific manner after anti–CD19-CAR–transduced T-cell infusions. Anti–CD19-CAR–transduced T cells have great promise to improve the treatment of B-cell malignancies because of a potent ability to eradicate CD19+ cells in vivo; however, reversible cytokine-associated toxicities occurred after CAR–transduced T-cell infusions. This trial was registered with ClinicalTrials.gov as NCT00924326.

Description: Gene therapy of human cancer using genetically engineered lymphocytes is dependent on the identification of highly reactive T-cell receptors (TCRs) with antitumor activity. We immunized transgenic mice and also conducted high-throughput screening of human lymphocytes to generate TCRs highly reactive to melanoma/melanocyte antigens. Genes encoding these TCRs were engineered into retroviral vectors and used to transduce autologous peripheral lymphocytes administered to 36 patients with metastatic melanoma. Transduced patient lymphocytes were CD45RA− and CD45RO+ after ex vivo expansion. After infusion, the persisting cells displayed a CD45RA+ and CD45RO− phenotype. Gene-engineered cells persisted at high levels in the blood of all patients 1 month after treatment, responding patients with higher ex vivo antitumor reactivity than nonresponders. Objective cancer regressions were seen in 30% and 19% of patients who received the human or mouse TCR, respectively. However, patients exhibited destruction of normal melanocytes in the skin, eye, and ear, and sometimes required local steroid administration to treat uveitis and hearing loss. Thus, T cells expressing highly reactive TCRs mediate cancer regression in humans and target rare cognate–antigen-containing cells throughout the body, a finding with important implications for the gene therapy of cancer. This trial was registered at www.ClinicalTrials.gov as NCI-07-C-0174 and NCI-07-C-0175.

Description: T cells expressing chimeric antigen receptors (CAR) that target B-cell maturation antigen (BCMA) recognize and eliminate multiple myeloma (MM). BCMA is expressed by nearly all cases of MM. BCMA has a restricted expression pattern on normal cells. To reduce the risk of recipient immune responses against CAR T cells, we used a novel, fully-human, heavy-chain-only anti-BCMA binding domain designated FHVH33 instead of a traditional single-chain variable fragment (scFv). The FHVH33 binding domain lacks the light chain, artificial linker sequence, and 2 associated junctions of a scFv. We constructed a CAR designated FHVH33-CD8BBZ. FHVH33-CD8BBZ was encoded by a γ-retroviral vector and incorporated FHVH33, CD8α hinge and transmembrane domains, a 4-1BB costimulatory domain, and a CD3ζ domain. T cells expressing FHVH33-CD8BBZ are designated FHVH-BCMA-T. On this clinical trial, patients received 300 mg/m2 of cyclophosphamide and 30 mg/m2 of fludarabine on days -5 to -3 followed by infusion of FHVH-BCMA-T on day 0. Twenty-one FHVH-BCMA-T infusions have been administered on 5 dose levels (DL), 0.75x106, 1.5x106, 3x106, 6x106 and 12 x106 CAR+ T cells/kg of bodyweight. DL4 (6 x 106 CAR+ T cells/kg) was identified as the maximum feasible dose (MFD) after weighing toxicity, efficacy and manufacturing factors. Patients are now being enrolled on an expansion phase to test the MFD. One patient (Patient 11) received 2 treatments. Four patients have been enrolled who were not ultimately treated. The median age of the patients enrolled is 64 (range 41-72). Patients received a median of 6 prior lines of therapy (range 3-12). Of the 20 FHVH-BCMA-T treatments evaluable for response, 18 (90%) resulted in objective responses (OR). Twelve treatments resulted in VGPR, complete remission (CR) or stringent complete remission (sCR). Ten patients (50%) have ongoing responses that range between 0-80 weeks (6 sCR/CRs, 3 VGPRs, 1 PR). At the highest two DLs (8 patients), 7 patients (88%) have ongoing responses (median duration 20 weeks, range 0+ to 35+ weeks); progressive MM occurred in only 1 patient who had evidence of spinal cord compression on day +5 due to a rapidly expanding plasmacytoma, which required early intervention with high-dose corticosteroid and radiation therapy. Of the 8 patients evaluated for response who had high-risk cytogenetics at baseline, 7 had ORs. Responses are ongoing in 2 patients with TP53 mutations and 1 patient with t(4;14) translocation. Ten treated patients came off study due to progressive MM (9 patients) or death from other causes (1 patient, influenza). Two of 4 patients who had plasmacytomas evaluated for BCMA expression at relapse had evidence of BCMA-negative MM. Four patients had bone marrow aspirates evaluated for BCMA-expression before treatment and at the time of relapse; 3 of these patients had evidence of loss of BCMA expression at relapse. Of 21 FHVH-BCMA-T treatments administered, 20 (95%) were followed by cytokine release syndrome (CRS) with 16 (76%) cases of grade 1 or 2 CRS, 4 cases (19%) of grade 3 CRS, and no cases of grade 4 CRS. Three patients received tocilizumab. The median peak C-reactive protein after all 21 treatments was 196.9 mg/L. Of 21 total treatments, 8 (38%) were followed by neurologic toxicity; there were 5 cases of grade 1-2 neurologic toxicity (headache, dysarthria, confusion, delirium), 2 cases of grade 3 neurologic toxicity (confusion), and 1 patient with grade 4 spinal cord compression due to progressive MM. Two patients received corticosteroids to manage neurologic toxicities. A median of 3.0% (range 0-95%) of bone marrow T cells were CAR+ when assessed by flow cytometry 14 days after FHVH-BCMA-T infusion. We assessed blood CAR+ cells by quantitative PCR. The median peak level of CAR+ cells was 121 cells/µl (range 3-359 cells/µl) and the median day post-infusion of peak blood CAR+ cell levels was 12 (range 7-14). The results from this phase 1 trial demonstrate that FHVH-BCMA-T cells can induce deep and durable responses of relapsed MM with manageable toxicities. Assessment of durability of responses at the maximum feasible dose is a critical future plan. Accrual to the expansion cohort continues. Table Disclosures Manasanch: Novartis: Research Funding; Adaptive Biotechnologies: Honoraria; GSK: Honoraria; JW Pharma: Research Funding; Merck: Research Funding; Quest Diagnostics: Research Funding; Takeda: Honoraria; Sanofi: Honoraria; BMS: Honoraria; Sanofi: Research Funding. Rosenberg:Kite, A Gilead Company: Consultancy, Patents & Royalties, Research Funding. Kochenderfer:Kite, a Gilead company: Patents & Royalties, Research Funding; Celgene: Patents & Royalties, Research Funding; bluebird, bio: Patents & Royalties. OffLabel Disclosure: cyclophosphamide 300 mg/m2 fludarabine 30 mg/m2 Conditioning chemotherapy prior to CAR T-cell infusion