Pre-conditioning Chemotherapy Research Articles

Abstract 35: In situ CAR T cell engineering using lipid nanoparticles for B cell lymphoma therapy

Abstract Chimeric antigen receptor (CAR)-T cell therapy represents a breakthrough in immunotherapy, offering promising outcomes in the management of hematological malignancies. Current CAR-T cell in vitro manufacturing routes involve T cell isolation, purification, activation, gene transduction and cell expansion. The process duration and the costs present significant barriers. Therefore, there is a need for innovative strategies to address these concerns. Herein, we developed lipid nanoparticles (LNPs) to deliver CAR-mRNA efficiently and safely to T cells in vivo, thereby enabling in situ CAR-T cell engineering. By optimizing their composition and introducing anti-CD5 as the targeting ligand, we were able to enhance mRNA delivery and T cell transfection efficiency while maintaining T cell function. Furthermore, to augment T cell responsiveness to exogenous genetic elements, we investigated the pretreatment of T cells with interleukin (IL-7), thereby modulating T cell homeostasis by enhancing survival and proliferation, and rendering the cells more receptive to exogenous genetic modifications. We tracked firefly luciferase (FLuc) in naïve Balb/c mice using in vivo and ex vivo bioluminescence imaging after intravenous injection of anti-CD5 FLuc-mRNA LNPs. We observed positive mRNA expression in lymphoid organs, particularly in the spleen. Additionally, we harvested the lymphoid organs, and performed immunophenotyping analysis using flow cytometry after the administration of anti-CD5 LNPs encapsulating mRNA encoded CD19-CAR with a flag tag. We showed enhanced LNP binding in 65.2% of T cells and CAR expression in 11.64% of T cells as compared with non-treated controls, anti-CD5 FLuc-mRNA LNPs, or IgG CAR-mRNA LNPs. In a CD19+ A20 tumor-bearing mouse model, treatment with CAR-LNPs resulted in a significant increase in chemoattractants (CCL2, CCL4, CCL5, CCL7 and CXCL10) and pro-inflammatory cytokines (TNF-α, IFN-γ, IL6, IL8 and IL15) in blood, and infiltration of T cells and other immune cells in tumors, compared to the non-treated control group over 48 hours post treatment. In vivo engineering allows simultaneous CAR T cell engineering and delivery, reducing the time between manufacturing and treatment, minimizing contamination risks, eliminating complex ex vivo processes, and reducing the need for high-dose preconditioning chemotherapy. In conclusion, the adoption of in situ CAR-T cell production holds promise for improving this therapeutic approach. The authors acknowledge the funding support from NIHR01CA253316 and Leukemia and Lymphoma Society (LLS, Grant ID: 8022-20) Citation Format: Nisi Zhang, Elise Robinson, Angelie Rivera-Rodriguez, James Wang, Yutong Guo, Bo Wu, Spencer K. Tumbale, Marina Raie, Mohammed Inayathullah, Debra K. Czerwinski, Ronald Levy, Katherine W. Ferrara. In situ CAR T cell engineering using lipid nanoparticles for B cell lymphoma therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 35.

Preclinical evaluation of cyclophosphamide and fludarabine combined with CD19 CAR-T in the treatment of B-cell hematologic malignancies in vivo.

Chimeric antigen receptor T (CAR-T) cell therapy has achieved marked therapeutic success in ameliorating hematological malignancies. However, there is an extant void in the clinical guidelines concerning the most effective chemotherapy regimen prior to chimeric antigen receptor T (CAR-T) cell therapy, as well as the optimal timing for CAR-T cell infusion post-chemotherapy. We employed cell-derived tumor xenograft (CDX) murine models to delineate the optimal pre-conditioning chemotherapy regimen and timing for CAR-T cell treatment. Furthermore, transcriptome sequencing was implemented to identify the therapeutic targets and elucidate the underlying mechanisms governing the treatment regimen. Our preclinical in vivo evaluation determined that a combination of cyclophosphamide and fludarabine, followed by the infusion of CD19 CAR-T cells five days subsequent to the chemotherapy, exerts the most efficacious therapeutic effect in B-cell hematological malignancies. Concurrently, RNA-seq data indicated that the therapeutic efficacy predominantly perturbs tumor cell metabolism, primarily through the inhibition of key mitochondrial targets, such as C-Jun Kinase enzyme (C-JUN). In summary, the present study offers critical clinical guidance and serves as an authoritative reference for the deployment of CD19 CAR-T cell therapy in the treatment of B-cell hematological malignancies.

Phase I Clinical Study of Humanized BCMA-Single-Domain Antibodies-Targeting CAR T (BCMA-CART) in Patients with Relapsed/Refractory Multiple Myeloma

Background:The CAR structure adopted by CART-BCMA is composed of a single-domain antibody targeting BCMA, CD8 hinge region, transmembrane region, 4-1BB co-stimulatory domain, and CD3-ζ T cell activation domain. In the phase I clinical study (NCT05346198) carried out in China, the safety and efficacy of CART-BCMA were initially evaluated through the dose escalation + dose expansion design, and the recommended dose (RD dose) for follow-up studies was determined as well. Method:Enrolled patients with relapsed and/or refractory multiple myeloma (RRMM) had previously received at least 3 lines of therapy including at least one proteasome inhibitor and one immune modulator. After lymphatic preconditioning chemotherapy (program: fludarabine 30mg/m 2/d and cyclophosphamide 300mg/m 2/d, -5, -4, -3, for 3 consecutive days), all patients received a single dose of CART-BCMA at 2.5×10 6, 5×10 6 and 7.5×10 6 CAR-positive T cells/kg (subject body weight), according to the dose level in which they were enrolled. R esults :Up to June 26, 2023, a total of 15 cases of RRMM received 2.5×10 6 CAR-positive T cells/kg (n=3), 5×10 6 CAR-positive T cells/kg (n=11) or 7.5×10 6 CAR-positive T cells/kg (n=1) dose level of CART-BCMA cell infusion therapy on the basis of the dose level in which they were enrolled. The median follow-up time was 14.42 months (range: 10.2-26.6 months). The median age of the subjects was 63.0 years old (range: 36-73 years old) (Table 1), 73.3% of the subjects (n=11) had previously received ≥4 lines of multiple myeloma therapy, and the median line of treatment was 5 lines (range: 3-9 lines), among which, 2 subjects (13.3%) had previously received autologous hematopoietic stem cell transplantation, and 4 subjects (26.7%) had relapsed/refractory diseases after previous treatment with proteasome inhibitors, immune modulators and CD38 monoclonal antibodies (three-drug relapsed/refractory). Nine subjects (60.0%) had high-risk cytogenetic abnormalities according to sMART 3.0 criteria, and 6 subjects (40.0%) had extramedullary plasmacytoma. The most common grade ≥3 adverse events were hematological toxicity, including decreased neutrophil count (n=13, 86.7%), decreased white blood cell count (n=12, 80.0%), decreased lymphocyte count (n=10, 66.7%), anemia (n=8, 53.3%), decreased platelet count (n=4, 26.7%). The first patient in the 7.5×10 6 CAR-positive T cells/kg dose group had a dose-limiting toxicity (DLT) event of grade 4 platelet count decrease, and no DLT event occurred in the other low-dose groups (2.5 and 5×10 6 CAR-positive T cells/kg). All 15 patients (100.0%) developed grade 1-2 cytokine release syndrome (CRS), no grade ≥3 CRS occurred, and the median time to CRS was 2.0 days (range: 1-13 days) , with a median duration of 7.0 days (range: 2 to 17 days). After the occurrence of CRS, all patients recovered without sequelae after supportive treatment, and 6 patients (40%) received tocilizumab (3 subjects received 2 doses, 3 subjects received 1 dose), 4 patients (26.7%) used glucocorticoids. There was no event of immune effector cell-associated neurotoxicity syndrome (ICANS), and no death event occurred. The median time to the first response (TTR) of the patients was 0.953 months (range: 0.92 to 2.23 months). All 15 patients who received CART-BCMA infusion achieved remission, and the overall remission rate (ORR) ( At least achieve PR or better efficacy) was 100% (95%CI, 78.20%-100.00%), as shown in Figure 1, among which, the best response of 9 patients (60%) was strict complete remission ( sCR), 5 patients (33.3%) achieved very good partial response (VGPR), and 1 patient (6.7%) achieved PR. All sCR patients achieved MRD negativity. The ORR of 6 patients with extramedullary plasmacytoma was 100%, of which 2 achieved sCR and 4 achieved VGPR. Notably, gradual deepening of remission was observed in 12 patients (80%), of which 10 patients (66.7%) further deepened the depth of remission on days 60-90 after infusion, and 2 patients (13.3%) were assessed sCR at day 360. Conclusion:Data from this phase 1 clinical study showed that CART-BCMA is well tolerated and highly efficacious in patients with RRMM. Patients with extramedullary plasmacytoma had the comparable response to those without extramedullary diseases. Notably, 12 patients (80%) patients elicted deeper response after 3 months of CART-BCMA infusion

Phase 1 trial of 4-1BB-based adoptive T-cell therapy targeting human telomerase reverse transcriptase in patients with advanced refractory solid tumors

Background aimsHuman telomerase reverse transcriptase (hTERT) is an attractive target for anti-cancer therapies. We developed an effective method for generating hTERT-specific CD8+ T cells (hTERT-induced natural T cells [TERTiNTs]) using peripheral blood mononuclear cells (PBMCs) from patients with solid cancers and investigated their feasibility and safety. MethodsThis was a single-center phase 1 trial using a 3 + 3 dose escalation design to evaluate six dose levels of TERTiNTs. PBMCs from each patient were screened using an hTERT peptide panel to select those that stimulated CD8+ T cells. The four most stimulatory peptides were used to produce autologous CD8+ T cells from patients refractory or intolerant to standard therapies. Eligible patients received a single intravenous infusion of TERTiNTs at different dose levels (4 × 108 cells/m2, 8 × 108 cells/m2 and 16 × 108 cells/m2). Pre-conditioning chemotherapy, including cyclophosphamide alone or in combination with fludarabine, was administered to induce lymphodepletion. ResultsFrom January 2014 to October 2019, a total of 24 patients with a median of three prior lines of therapy were enrolled. The most common adverse events were lymphopenia (79.2%), nausea (58.3%) and neutropenia (54.2%), mostly caused by pre-conditioning chemotherapy. The TERTiNT infusion was well tolerated, and dose-limiting toxicities were not observed. None of the patients showed objective responses. Seven patients (30.4%) achieved stable disease with a median progression-free survival of 3.9 months (range, 3.2–11.3). At the highest dose level (16 × 108 cells/m2), four of five patients showed disease stabilization. ConclusionsThe generation of TERTiNTs was feasible and safe and provided an interesting disease control rate in heavily pre-treated cancer patients.

Co-Expression of an shRNA Targeting MICA/Micb Improves the Clinical Activity of a NKG2D-Based CAR T in Patients with Relapsed / Refractory AML/MDS

While CAR T cell therapy has delivered impressive clinical efficacy in B cell malignancies, similar levels of clinical activity have not been demonstrated in acute myeloid leukemia (AML). One underlying reason for this lack of translation is the relative paucity of validated CAR T targets. Major Histocompatibility Complex Class 1 related proteins MICA and MICB along with the UL16 binding proteins 1-6 (ULBP1-6) are frequently over-expressed on AML and myelodysplastic syndrome (MDS) blasts. The Natural Killer Group 2D (NKG2D) is a single receptor able to bind MICA, MICB and ULBP1-6, thus providing a potentially powerful approach that could be exploited to target this family of targets thereby providing a novel CAR T approach for AML/MDS.Expressing the NKG2D receptor fused to the human CD3z cytoplasmic domain generates a CAR that, when expressed in primary T cells, generates a CAR T product (termed CYAD-01) that showed good anti-tumor activity in preclinical models. In clinical trials, CYAD-01 showed a good tolerability profile but with a disappointing level of clinical activity when combined with cyclophosphamide / fludarabine preconditioning (DEPLETHINK trial, NCT03466320).We hypothesised that the transient expression of MICA/MICB on the CAR T itself may inhibit the activity of the NKG2D CAR through self-targeting and consequent fratricide. We developed a single shRNA able to knockdown both MICA and MICB. Co-expression of this shRNA with the NKG2D CAR generated a second generation CAR T product termed CYAD-02 which was examined in a highly similar AML/MDS patient population and preconditioning regimen as employed in the DEPLETHINK trial.CYAD-02 was evaluated in the the first-in-human CYCLE-1 trial (NCT04167696) in patients with r/r AML/MDS. The dose-escalation phase evaluated three dose-levels (DL) (1x10 8, 3x10 8 and 1x10 9 total cells per infusion), administered as a single infusion after standard preconditioning chemotherapy (cyclophosphamide 300 mg/m²/day and fludarabine 30 mg/m²/day, daily for 3 days) according to a classic 3+3 design.As of July 2021, 11 patients have been treated with CYAD-02 at the different dose-levels (3 at each DL1 and 2 and 5 at DL3). In terms of safety and tolerability, there was no evidence of a differential safety profile of CYAD-02 within the CYCLE-1 trial as compared to that observed in the CYAD-01 clinical trial. Of note, five patients enrolled in all 3 DLs experienced Grade ≥ 3 adverse events (AE) at least possibly related to CYAD-02 (cytokine release syndrome, febrile neutropenia, white blood cell count decreased, infusion related reaction).With respect to clinical activity, seven patients in total achieved stable disease (2 at DL1, 3 at DL2 and 2 at DL3) with 4 demonstrating evidence of transient blast reduction or anti-leukemic activity (decrease of at least 50% of the bone marrow blasts). In addition, two MDS patients at DL3 achieved a marrow complete response. Overall, this suggests dose dependent response to CYAD-02. Furthermore, patients receiving CYAD-02 cells seem to display a greater duration of response and stronger blast reduction as compared to patients who received CYAD-01 in DEPLETHINK.Interestingly, peak engraftment levels were higher for CYAD-02 compared to CYAD-01 at the same dose (DEPLETHINK trial). At DL3, CYAD-02 cells could be readily detected in peripheral blood of 4/5 patients through month 2. In addition, and unlike what is reported in B cell CAR T-cells trials, there was very limited evidence of elevated homeostatic cytokines (IL-7/IL-15) following CyFlu administration with IL-15 not detected in any of the patients and IL-7 showing only a minor increase in 2 patients.The knockdown of MICA/MICB appears to have a positive contribution to the initial clinical activity of CYAD-02 as compared to that achieved with the first generation CYAD-01 CAR T, together with good safety and tolerability. The lack of homeostatic cytokines after preconditioning, likely limiting the engraftment and activity of CAR T cells, may be related to the biology of myeloid malignancies. One approach to further drive the potency of NKG2D-based CAR T cells would likely be armoring the CAR T through using the T cell as a vehicle to secrete cytokines alongside the CAR. Overall, shRNA knockdown technology provides a means to modify CAR T function and here shows that single shRNA can target two independent genes to enhance the phenotype of the CAR Ts. DisclosuresDeeren: Alexion: Consultancy; BMS: Consultancy; Incyte: Consultancy; Novartis: Consultancy; Sanofi: Consultancy, Research Funding; Sobi: Consultancy; Takeda: Consultancy. Lin: AbbVie, Aptevo Therapeutics, Astellas Pharma, Bio-Path Holdings, Celgene, Celyad, Genentech-Roche, Gilead Sciences, Incyte, Jazz Pharmaceuticals, Novartis, Ono Pharmaceutical, Pfizer, Prescient Therapeutics, Seattle Genetics, Tolero, Trovagene: Research Funding. Alcantar-Orozco: Celyad Oncology: Current Employment. Dheur: Celyad Oncology: Current Employment. Breman: Celyad Oncology: Current Employment. Braun: Celyad Oncology: Current Employment. Lonez: Celyad Oncology: Current Employment. Gilham: Celyad Oncology: Current Employment. Flament: Celyad Oncology: Current Employment. Lehmann: Celyad Oncology: Current Employment.

The Safety and Efficacy of a CRISPR/Cas9-Engineered Universal CAR-T Cell Product (CTA101) in Patients with Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia

Introduction Although autologous CAR-T therapy targeting CD19+ B-cell has proven efficacy in hematological malignancies. The challenges such as undesirable waiting time, possible manufacturing failures and high cost, remain to be solved. In addition, antigen-loss/downregulation leads to treatment failure after single-target CAR-T therapy. To tackle these issues, we developed a universal CD19/CD22-targeting CAR-T cell with the TRAC region and CD52 gene disrupted using CRISPR/Cas9 technology. Pre-clinical data demonstrated the safety of CRISPR gene editing and the anti-leukemia ability of CTA101. Method Pts with CD19+ or CD22+ r/r B-ALL received a single dose of CTA101 with traditional 3+3 dose escalation (dose level: 1, 3 and 6×106 CAR+ T cells/kg). Prior to CTA101 infusion, pts received pre-conditioning chemotherapy regimen consisting of cyclophosphamide, fludarabine and alemtuzumab. The primary endpoint is the frequency of DLTs and AEs and secondary endpoints including ORR, OS, cellular PK, etc. (NCT04227015) Results Characteristics of CTA101 CTA101 was manufactured by electroporation of ribonucleoprotein complexes (RNP) comprising Cas9 loaded with sgRNA targeting TRAC and CD52 followed by lentiviral transduction of the CAR transgene. All products were expanded above 100-folds after 10-12 days manufacturing (Fig.1a). CAR expression was detected by FCM staining, ranging from 40~80% (Fig.1b). The frequency of editing as determined by flow cytometry was consistently above 85% (88%-97%) for TRAC and above 65% (68%-83%) for CD52 (Fig.1c, 1d). The CD19/CD22 dual targeting universal CAR-T cells showed potent antigen specific cytotoxicity, and mitigated tumor antigen escape (Fig.1e). Whole genome sequencing was carried out to assess the on-target and off-target editing events. While most mutations were on target, a few off-target mutations were identified, which needed further investigation (Fig.2). QPCR assays identified no detectable rearrangements occurred with the simultaneous editing of four loci: TRAC and CD52 (TRAC-CD52) during the manufacture process. Residual Cas9 protein was quantified during the manufacturing process, showing declining levels that were 0.195 fg/cell (detection limit of sensitive ELISA) in the final product. Clinical result As of August 5th 2020, 8 adult pts were screened, and 6 adult pts were enrolled. All of 6 patients received one infusion of CTA101 (DL1: 3 pts; DL2: 3 pts), with no more than 8 days between enrollment and infusion. The median age of 6 pts was 49 years (range, 26 to 56), the median prior lines of therapies were 5 (range, 2 to 8), and the median marrow blast percentage was 52% (range, 1 to 82). 3 pts had hyperleukocytosis prior to enrollment with difficulties in apheresis for autologous CAR-T, 1 relapsed after autologous CD22 CAR-T, and 3 had high-risk genomic lesions (Table 1). All 6 pts were available for evaluation of safety and efficacy. No DLTs, GvHD, ICANS and death occurred to date. All pts experienced CRS (3 G1, 2 G2, 1 G3), and the G3 CRS recovered within 7 days with one dose of tocilizumab and glucocorticoids. Other common AEs were prolonged cytopenia (3 G3), virus reactivation/infections (CMV 1 G2, 2 G3; ADV 1 G1), bacterial pneumonia (1 G3), and fungal sepsis (1 G3). The majority of events recovered to date. No replication competent lentivirus (RCL) has been detected. On D28 after CTA101 infusion, 5/6 (83.3%) pts achieved CR/CRi, and 5/5 (100%) pts achieved MRD-. With a median follow-up of 85 days (range, 53 to 202), 4/5 pts remained MRD-, 1/5 had MRD+ CR (Fig. 3). Only 1 pt received HSCT in remission on D60. Expansion had been observed in all pts and peaked from D10 to D14 (Fig.4). The correlation among dose level, donor difference, tumor burden and degree of expansion could not be identified. The median duration of persistence was 42 days. The lowest peak expansion was detected by qPCR in the pt without response and whose T lymphocyte recovered within D7, while FCM did not detect CTA101 expansion in the pt. Conclusions CTA101 demonstrates manageable safety profile and deep response of high MRD- CR/CRi rate. No GvHD and CRISPR/Cas9 genome editing associated AEs occurred. Early data of cellular PK and efficacy illustrate that CRISPR gene editing does not curtail the expansion and anti-leukemia capacity of CAR-T. Updated data, including long term gene editing-related AEs, will be presented after further follow-up. Disclosures Zhou: Nanjing Bioheng Biotech Co., Ltd: Current Employment. Ge:Nanjing Bioheng Biotech Co., Ltd: Current Employment. Han:Nanjing Bioheng Biotech Co., Ltd: Current equity holder in private company. Wang:Nanjing Bioheng Biotech Co., Ltd: Current Employment. Zhang:Nanjing Bioheng Biotech Co., Ltd: Current Employment. Ren:Nanjing Bioheng Biotech Co., Ltd: Current equity holder in private company.

The Lymphoma Tumor Microenvironment Influences Toxicity after CD19 CAR T Cell Therapy

Introduction: Of patients receiving CD19 CAR T cell therapy for large B cell lymphoma (LBCL), approximately 1 in 10 experience severe cytokine release syndrome (CRS) and 1 in 3 experience severe neurotoxicity. While CAR T cells trigger the onset of these toxicities, CRS and neurotoxicity are thought to occur as a consequence of activated myeloid cells amplifying cytokine and catecholamine release, thereby stimulating inflammation both systemically and at the blood-brain barrier. However, patient and tumor-related factors that account for differences in the amount of toxicity remain poorly understood. Methods: Serum cytokine levels were measured on an ELLA point of care device prior to lymphodepleting chemotherapy and throughout inpatient treatment with CD19 CAR T cell therapy (axicabtagene ciloleucel) for LBCL. Catecholamine levels were measured as we have previously reported. Tumor biopsies were taken within 1 month prior to infusion of CAR T cells. RNA expression was measured by RNAseq and/or a Nanostring IO360 panel consisting of 770 genes found in the tumor microenvironment (TME) in cancer. Analysis used nSolver to identify cell types, GSEA and differential gene expression between groups. Mouse CAR T cell studies utilized mouse CD19-targeted CAR T cells derived from C57BL/6 splenocytes and cultured in vitro with myeloid cells and target cells to evaluate cytotoxicity and/or cytokine secretion. Elicited mouse macrophages were collected from peritoneal fluid 4 days after IP injection of 3% Brewer's thioglycollate medium. In vivo studies with mouse CD19-targeted CAR T cells were performed in IL2Ra-/- mice given cyclophosphamide as a pre-conditioning chemotherapy followed by adoptive transfer and analyses for CAR T cell and B cell persistence, as well as cytokines. Results: Of 58 patients undergoing CD19 CAR T cell therapy for LBCL, 8 (14%) had severe (grade 3 or higher) CRS and 16 (28%) had severe (grade 3 or higher) neurotoxicity. At baseline, peripheral blood levels of IL-6, IFN-γ, IL-15 and ferritin were significantly higher in patients who would subsequently experience severe CRS and severe neurotoxicity. Confirming our recent animal model of CRS we determined that peak serum catecholamine levels were higher in patients experiencing severe CRS. To identify if myeloid cells potentiate cytokine release we co-cultured CAR T cells with CD19 target and macrophages obtained from elicited mouse peritoneum. When these macrophages were added, IL-6 release from CAR T cells significantly increased compared to when macrophages were absent. Next, we studied the baseline TME in LBCL CAR T patients. Of 36 patients, 10 (27%) experienced severe neurotoxicity following CAR T cell therapy. By cell type score, the severe neurotoxicity group had a lower expression of genes associated with T cells overall and specifically Tregs. Also significantly lower in the severe neurotoxicity group were T cell genes including multiple subunits of CD3, CD3ζ, FOXP3, ICOS, CD62L and others. Association of increased T cell infiltration in the TME with low neurotoxicity raised the possibility that suppressive T cell subsets play a role in limiting toxicity post-CAR T cell therapy. To test this hypothesis, we injected CD19-targeted CAR T cells into an immune competent mouse model of Treg depletion (IL2Ra-/-) with established CD19+ leukemia. Treg deficient mice experienced a massive cytokine release after CAR T infusion and died prematurely due to CAR T toxicity compared to control mice with Tregs intact. Conclusions: Our observations suggest that the incidence of severe toxicity following CD19 CAR T cell therapy is influenced by baseline characteristics that are present prior to the infusion of CAR T cells. These include systemic inflammation characterized by high cytokine levels and a TME notable for a lack of infiltrating T cells. We posit a model whereby inflammation primes myeloid cells that are further activated upon CAR T cell infusion to release toxic amounts of cytokines and catecholamines. T cell subsets in the TME may modulate CAR T cells at the site of antigen encounter and prevent excessive CAR T activation. Reducing systemic inflammation or encouraging T cell infiltration into tumor prior to CAR T infusion are potential strategies for lowering the toxicity associated with CAR T therapy. Disclosures Jain: Kite/Gilead: Consultancy. Chavez:Kite Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Genentech: Speakers Bureau; Janssen Pharmaceuticals, Inc.: Speakers Bureau. Shah:Novartis: Honoraria; Spectrum/Astrotech: Honoraria; Celgene/Juno: Honoraria; Kite/Gilead: Honoraria; Incyte: Research Funding; Jazz Pharmaceuticals: Research Funding; Pharmacyclics: Honoraria; Adaptive Biotechnologies: Honoraria; AstraZeneca: Honoraria. Bachmeier:Kite/Gilead: Speakers Bureau. Mullinax:Iovance: Research Funding. Locke:Novartis: Other: Scientific Advisor; Cellular BioMedicine Group Inc.: Consultancy; Kite: Other: Scientific Advisor. Davila:Anixa: Consultancy; Precision Biosciences: Consultancy; Novartis: Research Funding; GlaxoSmithKline: Consultancy; Adaptive: Consultancy; Celgene: Research Funding; Atara: Research Funding; Bellicum: Consultancy.

Final report of a pilot trial combining ipilimumab and adoptive cell therapy.

147 Background: We previously confirmed the feasibility of adoptive cell therapy (ACT) with tumor infiltrating lymphocytes (TIL) for patients with advanced melanoma. Patients successfully treated had a 38% response rate, but patient attrition due to progression before ACT (21%) resulted in a response rate of only 26% based on intent to treat (IIT) analysis. We hypothesized that combination immunotherapy would decrease attrition due to progression. Here we present the final report of a pilot trial combining ipilimumab (IPI) and ACT. Methods: Thirteen patients with metastatic melanoma were accrued to an IRB-approved trial. All had >1 cm3 of soft tissue/nodal metastases amenable to resection leaving residual disease. Patients received 3 mg/kg of IPI two weeks prior to tumor resection for TIL generation. One week following resection, a second dose of IPI was administered. ACT included pre-conditioning chemotherapy and TIL infusion followed by IL-2. Two additional doses of IPI were given 2 and 5 weeks after ACT. Feasibility was a primary endpoint and considered achieved if ≥ 2 doses of IPI and TIL were infused to at least 60% of all patients. The clinical responses were assessed by RECIST 1.1 criteria at 12 weeks following TIL transfer. Results: All patients received at least 2 doses of IPI, and 12 of the 13 patients (92%) received TIL. One patient (7%) dropped out due to progression before TIL infusion. TIL were expanded from 47.2% of tumor fragments and 58.7% of these fragments generated TIL reactive to autologous tumor. Median number of infused TIL was 6.5e10 (2.29e10-1.04e11) and median 85% were CD8+ (27-99). At 12 weeks following infusion, of the 13 patients enrolled, there were 6 responders (46%). Median progression-free survival was 7.4 months (1.4-42.2). Grade ≥3 immune-related adverse events included colitis (1), uveitis (1), and hypothyroidism (1). Conclusions: IPI combined with ACT with TILs for patients with advanced melanoma is feasible with decreased attrition due to progression and is associated with promising clinical results based upon ITT analysis. This combination approach of TIL cell therapy and co-inhibitory blockade serves as a model for future efforts to improve the efficacy of immunotherapy for patients with cancer. Clinical trial information: NCT01701674.

Oncolytic Adenoviruses Armed with Tumor Necrosis Factor Alpha and Interleukin-2 Enable Successful Adoptive Cell Therapy

Adoptive cell therapy holds much promise in the treatment of cancer but results in solid tumors have been modest. The notable exception is tumor-infiltrating lymphocyte (TIL) therapy of melanoma, but this approach only works with high-dose preconditioning chemotherapy and systemic interleukin (IL)-2 postconditioning, both of which are associated with toxicities. To improve and broaden the applicability of adoptive cell transfer, we constructed oncolytic adenoviruses coding for human IL-2 (hIL2), tumor necrosis factor alpha (TNF-α), or both. The viruses showed potent antitumor efficacy against human tumors in immunocompromised severe combined immunodeficiency (SCID) mice. In immunocompetent Syrian hamsters, we combined the viruses with TIL transfer and were able to cure 100% of the animals. Cured animals were protected against tumor re-challenge, indicating a memory response. Arming with IL-2 and TNF-α increased the frequency of both CD4+ and CD8+ TILs in vivo and augmented splenocyte proliferation ex vivo, suggesting that the cytokines were important for T cell persistence and proliferation. Cytokine expression was limited to tumors and treatment-related signs of systemic toxicity were absent, suggesting safety. To conclude, cytokine-armed oncolytic adenoviruses enhanced adoptive cell therapy by favorable alteration of the tumor microenvironment. A clinical trial is in progress to study the utility of Ad5/3-E2F-d24-hTNFa-IRES-hIL2 (TILT-123) in human patients with cancer.

First pregnancies, live birth, and in vitro fertilization outcomes after transplantation of frozen-banked ovarian tissue with a human extracellular matrix scaffold using robot-assisted minimally invasive surgery

Ovarian tissue cryopreservation is an experimental fertility preservation method and the transplantation techniques are still evolving. We attempted to improve the technique with the utility of a human decellularized extracellular tissue matrix (ECTM) scaffold, robot-assisted minimally invasive surgery, and perioperative pharmacological support. We prospectively studied 2 subjects with hemophagocytic lymphohistiocytosis (patient A) and non-Hodgkin lymphoma (patient B) who underwent ovarian tissue cryopreservation at the age of 23 years, before receiving preconditioning chemotherapy for hematopoietic stem cell transplantation. Both experienced ovarian failure postchemotherapy and we transplanted ovarian cortical tissues to the contralateral menopausal ovary 7 and 12 years later, using a human ECTM scaffold and robotic assistance. The ECTM scaffold tissue compatibility was shown in preclinical studies. Patients also received estrogen supplementation and baby aspirin preoperatively to aid in the revascularization process. Ovarian follicle development was observed approximately 10 (patient A) and 8 (patient B) weeks after ovarian tissue transplantation. Following 8 and 7 cycles of invitro fertilization, 9 and 10 day-3 embryos were cryopreserved (patients A and B, respectively). While the baseline follicle-stimulating hormone (range 3.6-15.4 mIU/mL) levels near normalized by 7 months and remained steady postovarian transplantation in patient A, patient B showed improved but elevated follicle-stimulating hormone levels throughout (range 21-31 mIU/mL). Highest follicle yield was achieved 14 (8 follicles; patient A) and 11 (6 follicles; patient B) months postintervention. Patient A experienced a chemical pregnancy after the third frozen embryo transfer attempt. She then conceived following her first fresh invitro fertilization embryo transfer and the pregnancy is currently ongoing. Patient B conceived after the first frozen embryo transfer attempt and delivered a healthy girl at term. We report the first pregnancies after the minimally invasive transplantation of previously cryopreserved ovarian tissue with an ECTM scaffold. This approach seems to be associated with steady ovarian function after a follow-up of up to 2 years.

Early Experience with Clofarabine Pre-Conditioning Prior to Full Intensity or Reduced Toxicity Allogeneic Stem Cell Transplantation: A Promising New Therapy for the Treatment of Refractory Acute Leukaemia

AbstractAbstract 4511 Introduction:The outcome for patients with primary refractory or refractory relapse of acute leukaemia, particularly those with disease present at the time of transplant, remains very poor even using full intensity conditioning schedules. With the aim of improving outcome, we have employed the use of pre-conditioning chemotherapy prior to the delivery of both reduced toxicity (RTC) and full intensity transplants during the subsequent period of cytopenia. Initial results indicate feasibility and efficacy in this poor risk disease. The bi-halogen purine analogue Clofarabine has significant activity as a single agent for the treatment of ALL and AML and is well tolerated, characteristics suggesting Clofarabine is an ideal agent to use in pre-conditioning. Patients and methods:We have treated 11 patients with high-risk, refractory acute leukaemia or advanced myelodysplasia (MDS) using Clofarabine pre-conditioning to reduce disease burden before full intensity or RTC allogeneic transplantation. Patient characteristics for the two groups are shown below (Table 1).Table 1Median age (range)Sex (%)Underlying disease (%)MFPrimary refractory AMLRefractory Relapse of AMLRefractory MDS (RAEB2)Primary refractory Biphenotypic acute leukaemia33 (17–58)4 (36)7 (64)2 (18)7 (64)1 (9)1 (9)Clofarabine was administered as a single agent (40mg/m2/day for 5 days), five received RTC using Busulphan or Melphalan-containing transplant schedules; six full intensity total body irradiation (TBI) based conditioning. Indications for using Clofarabine included severe allergy to Cytarabine, heavy prior exposure to anthracycline or lack of response to other salvage agents. 10 of 11 patients had significant marrow involvement prior to administration of Clofarabine. Results:In this cohort we have not seen additional unexpected complications. One patient who received a RTC regimen, was treated for VOD on clinical suspicion but liver biopsy indicated grade 3–4 haemosiderosis only. Two patients who received TBI-based transplants suffered grade 3–4 mucositis. The extended period of pancytopenia compared with conventional transplant schedules was manageable, with no unexpected infectious complications. The median time to a neutrophil count of > 0.5 × 109/l was 18 days post stem cell infusion (range 12–33 days) and to a platelet count > 20 × 109/l was 13 days (range 11–32 days). All patients achieved ≥ 98% donor chimerism by day +30. 2 of 11 patients (18%) experienced grade 3–4 acute GvHD (1 cutaneous, 1 gut) which responded to additional immunosuppression. 9 of 10 patients with disease present at the time of Clofarabine achieved substantial bulk reduction or eradication of marrow leukaemic blasts following the Clofarabine. 5 of 11 patients died from disease relapse post allograft at 2–13 months post transplant, including the patient with Clofarabine-refractory disease. 6 patients are currently in CR at 1–77 months follow up.Overall survival for the 11 patients, using Kaplan-Meier analysis, is 48% with a median follow up of survivors of 26 months (range 1–77), shown below in figure 1: [Display omitted] Conclusions:The use of Clofarabine as a pre-conditioning agent prior to the administration of the transplant conditioning schedule is well tolerated with both full intensity and reduced toxicity protocols. This approach to allogeneic transplantation shows promise for the therapy of patients with high risk refractory acute leukaemia. Disclosures:Richardson:Genzyme: Advisory board Other, Research Funding. Off Label Use: Clofarabine is licensed for the treatment of relapsed/refractory ALL in paediatric and young adult patients. This paper includes discussion of use in the treatment of AML/high risk MDS for which the drug has orphan drug status in the EU.

The combination of cyclophosphamide and human T cells genetically engineered to target CD19 can eradicate established B‐cell lymphoma

T cells genetically engineered to express tumour-targeting receptors are attractive anti-cancer therapeutic agents. Human T cells engrafted with a chimeric receptor specific for the B-cell lymphoma antigen CD19 fused to the CD3zeta receptor (aCD19z) are functional in vitro. Current successful clinical protocols targeting melanoma use pre-conditioning chemotherapy in combination with T cells. This study demonstrated that interleukin-2 expanded aCD19z T cells combined with cyclophosphamide effectively treated five-day established Raji B-cell lymphoma in an immunocompromised model system with 50% of mice surviving >100 days. This observation strongly supports the combination of antibody targeted T cells with chemotherapy as a novel approach for the therapy of CD19(+) B-cell malignancies.

Spontaneous conceptions and live birth after heterotopic ovarian transplantation: is there a germline stem cell connection?

Ovarian cryopreservation and transplantation is an emerging technology to preserve fertility in women and children undergoing cancer treatment. Recent reports of live births after orthotopic transplantation raised hopes for the future success of this procedure. However, doubts remained whether the reported pregnancies were as a result of resumed function in the remaining ovary. We recently performed an autologous heterotopic ovarian transplantation in a 32-year-old Hodgkin lymphoma survivor who was menopausal for 2.5 years as a result of a preconditioning chemotherapy given before a hematopoietic stem cell transplant. Subsequent to the transplantation, the patient conceived twice within 3 months and delivered a healthy female child at 40 weeks of gestation. The occurrence of spontaneous pregnancies after heterotopic ovarian transplantation highlights the need for caution when interpreting the source of pregnancies in recipients with intact ovaries. On the other hand, the temporal relationship between the ovarian transplant and the spontaneous resumption of ovarian function and pregnancies in previously menopausal women is intriguing, especially in the light of recent reports of germ cell renewal and migration from the bone marrow to the ovary in rodents.

GASTROINTESTINAL (GI) ADENOVIRUS TREATED WITH ORAL RIBAVIRIN IN SEVERE COMBINED IMMUNODEFICIENCY (SCID). 53

JH presented at 5 months of age with FTT, and respiratory distress due to parainfluenza virus type III (PFIII). Our evaluation led to a diagnosis of SCID. Respiratory symptoms improved with long-term nebulized Ribavirin and supportive care, but GI tract adenovirus (AV) resulted in continuing management problems (cramps, diarrhea, FTT). For definitive therapy JH received a maternal-donor, T-cell-depleted bone marrow stem cell transplant(no pre-conditioning chemotherapy). T lymphocyte function reconstituted during the subsequent 3-4 months, with elimination of the PFIII. GVHD affecting the bone marrow developed, with ensuing life-threatening pancytopenia. Worsening GI symptoms and increase in stool AV were noted with anti-GVHD therapy(corticosteroids and cyclosporin A). We hypothesized that exacerbation of the AV infection was in part due to the immunosupressive treatment and, additionally, that the immune response generated against the AV was resulting in simultaneous activation of maternal T lymphocytes capable of causing and/or worsening the GVHD. Cognizance that systemic AV infections can be catastrophic in immunocompromised patients prompted us to escalate therapy. Recent studies indicating successful and less toxic usage of oral Ribavirin for the treatment of various viruses led us to consider this over parenteral therapy. Low dose therapy, 20 mg/kg/day was initiated, with equivocal results. One week later, dosing of 200 mg/kg/day resulted in immediate clinical improvement (reduction in vomiting, loose stools, abdominal cramping, and improved feeding). Stool AV was quantified by enumerating viral particles via electron microscopy. Post-treatment viral load was decreased to 20% of that of immediate pre-treatment levels. To our knowledge, this is the first report of oral Ribavirin therapy for GI tract AV infection. While long-term effects of Ribavirin remain unknown, clinical improvement in JH demonstrated that oral Ribavirin can be of benefit as anti-viral therapy in immunodeficient patients.

Treatment of advanced neuroblastoma with emphasis on intensive induction chemotherapy. A report from the study group of Japan

One hundred nine newly treated patients with advanced neuroblastoma were entered in this study between January 1985 and May 1989. The eligible patients included infants younger than 12 months of age with Stage IVA disease (bone cortex, distant lymph node, and/or remote organ metastases) and patients aged 12 months or older with Stage III or IV disease (IVA plus IVB with tumor crossing the mid-line and with metastases confined to bone marrow, liver, and skin). The patients first received six cyclic course of intensive chemotherapy (regimen A1), consisting of cyclophosphamide (1200 mg/m2), vincristine (1.5 mg/m2), tetrahydropyranyl adriamycin (pyrarubicin; 40 mg/m2), and cisplatin (90 mg/m2). Original tumors and the regional lymph node metastases were removed some time during these first six cycles of chemotherapy. The patients were further divided into three groups. Patients in course 1 received alternating treatment by regimen B (cyclophosphamide and ACNU) and intensified regimen A1, and those in course 2 were treated with alternating administration of regimen C (cyclophosphamide and DTIC) and intensified A1. Patients in course 3 were treated with bone marrow transplantation (BMT) preceded by high-dose preconditioning chemotherapy. Survival rates were 77% in Stage III and 54% in Stage IV at 2 years, and 70% in Stage III and 45% in Stage IV at 3 years. The major toxicities encountered were bone marrow suppression with leukocyte counts down to 100/mm3, mild cystitis, and hearing impairment. The 2-year survival rate was 78% in 21 patients who underwent BMT when complete remission was achieved. We concluded that our intensive induction chemotherapy is of significant value in increasing the rate of complete response, and in widening the indications for and achieving improved results of treatment with BMT.