Long-term stability of clinical-grade lentiviral vectors for cell therapy

The use of lentiviral vectors in cell and gene therapy is steadily increasing, both in commercial and investigational therapies. Although existing data increasingly support the usefulness and safety of clinical-grade lentiviral vectors used in cell manufacturing, comprehensive studies specifically addressing their long-term stability are currently lacking. This is significant considering the high cost of producing and testing GMP-grade vectors, the limited number of production facilities, and lengthy queue for production slots. Therefore, an extended shelf life is a critical attribute to justify the investment in large vector lots for investigational cell therapies. This study offers a thorough examination of essential stability attributes, including vector titer, transduction efficiency, and potency for a series of clinical-grade vector lots, each assessed at a minimum of 36 months following their date of manufacture. The 13 vector lots included in this study were used for cell product manufacturing in 16 different clinical trials, and at the time of the analysis had a maximum storage time at -80°C of up to 8 years. The results emphasize the long-term durability and efficacy of GMP-grade lentiviral vectors for use in ex vivo cell therapy manufacturing.

Intrathecal bivalent CAR T cells targeting EGFR and IL13Rα2 in recurrent glioblastoma: phase 1 trial interim results

Recurrent glioblastoma (rGBM) remains a major unmet medical need, with a median overall survival of less than 1 year. Here we report the first six patients with rGBM treated in a phase 1 trial of intrathecally delivered bivalent chimeric antigen receptor (CAR) T cells targeting epidermal growth factor receptor (EGFR) and interleukin-13 receptor alpha 2 (IL13Rα2). The study's primary endpoints were safety and determination of the maximum tolerated dose. Secondary endpoints reported in this interim analysis include the frequency of manufacturing failures and objective radiographic response (ORR) according to modified Response Assessment in Neuro-Oncology criteria. All six patients had progressive, multifocal disease at the time of treatment. In both dose level 1 (1 ×107 cells; n = 3) and dose level 2 (2.5 × 107 cells; n = 3), administration of CART-EGFR-IL13Rα2 cells was associated with early-onset neurotoxicity, most consistent with immune effector cell-associated neurotoxicity syndrome (ICANS), and managed with high-dose dexamethasone and anakinra (anti-IL1R). One patient in dose level 2 experienced a dose-limiting toxicity (grade 3 anorexia, generalized muscle weakness and fatigue). Reductions in enhancement and tumor size at early magnetic resonance imaging timepoints were observed in all six patients; however, none met criteria for ORR. In exploratory endpoint analyses, substantial CAR T cell abundance and cytokine release in the cerebrospinal fluid were detected in all six patients. Taken together, these first-in-human data demonstrate the preliminary safety and bioactivity of CART-EGFR-IL13Rα2 cells in rGBM. An encouraging early efficacy signal was also detected and requires confirmation with additional patients and longer follow-up time. ClinicalTrials.gov identifier: NCT05168423 .

Anti-BCMA/CD19 CAR T Cells with Early Immunomodulatory Maintenance for Multiple Myeloma Responding to Initial or Later-Line Therapy

We conducted a phase I clinical trial of anti-BCMA chimeric antigen receptor T cells (CART-BCMA) with or without anti-CD19 CAR T cells (huCART19) in multiple myeloma (MM) patients responding to third- or later-line therapy (phase A, N = 10) or high-risk patients responding to first-line therapy (phase B, N = 20), followed by early lenalidomide or pomalidomide maintenance. We observed no high-grade cytokine release syndrome (CRS) and only one instance of low-grade neurologic toxicity. Among 15 subjects with measurable disease, 10 exhibited partial response (PR) or better; among 26 subjects responding to prior therapy, 9 improved their response category and 4 converted to minimal residual disease (MRD)-negative complete response/stringent complete response. Early maintenance therapy was safe, feasible, and coincided in some patients with CAR T-cell reexpansion and late-onset, durable clinical response. Outcomes with CART-BCMA + huCART19 were similar to CART-BCMA alone. Collectively, our results demonstrate favorable safety, pharmacokinetics, and antimyeloma activity of dual-target CAR T-cell therapy in early lines of MM treatment.

SIGNIFICANCE

CAR T cells in early lines of MM therapy could be safer and more effective than in the advanced setting, where prior studies have focused. We evaluated the safety, pharmacokinetics, and efficacy of CAR T cells in patients with low disease burden, responding to current therapy, combined with standard maintenance therapy. This article is highlighted in the In This Issue feature, p. 101.

431 First-in-human phase I clinical trial evaluating intraperitoneal administration of MOv19-BBz CAR T cells in patients with alpha folate receptor-expressing recurrent high grade serous ovarian cancer

Background

Most women with epithelial ovarian cancer develop uniformly incurable disease recurrence. Chimeric antigen receptor (CAR) T cells pair the MHC-independent tumor-recognition capabilities of monoclonal antibodies with the cytotoxicity of effector T cells. The success of CAR T cell therapy in solid tumors has been hindered by (1) difficulty identifying highly expressed, tumor-specific, cell surface target antigens; (2) limited trafficking and infiltration; and (3) suboptimal cytotoxic activity. Alpha folate receptor (FRα) is a transmembrane protein involved in cellular folate transport; expression has been reported in 80% of ovarian cancer, with limited physiologic expression on epithelial cells including bronchial, renal, and intestinal tissue. We hypothesize that intraperitoneal administration of alpha folate receptor (FRα) directed CAR T cells with dual 4-1BB and TCRzeta signaling domains will circumvent the above challenges and be safe, feasible, and elicit anti-tumor responses.

Methods

We initiated a first-in-human phase I clinical trial to evaluate the feasibility, safety and preliminary efficacy of intraperitoneal administration of FRα directed CAR T cells with and without antecedent lymphodepleting chemotherapy (LDC) in women with recurrent high grade serous ovarian cancer. The lentivirally-transduced CAR is composed of a MOv19 anti-FRα-specific single chain variable fragment fused to 4-1BB and TCRzeta signaling domains. Eligible patients have persistent or recurrent high grade serous epithelial ovarian, fallopian tube, or primary peritoneal carcinoma that is not platinum refractory and expresses ≥2+ FRα staining in ≥70% of tumor cells. Subjects must have an ECOG performance status 0–1, measurable disease, adequate hematologic and organ function, and must have progressed on at least two prior chemotherapy regimens for advanced disease. Patients undergo biopsy pre-infusion and Day +14 after infusion. After same-day placement of an intraperitoneal catheter by Interventional Radiology, CAR T cells are administered via a single infusion on three dose cohorts: Cohort 1 (starting cohort), 1–3x107/m2 cells without LDC; Cohort 2, 1–3x107/m2 CAR T cells after LDC; Cohort 3, 1–3x108/m2 cells after LDC. Catheter is removed after infusion. A 3+3 dose escalation design to determine maximum tolerated dose (MTD) yields approximately 9 to 18 subjects. The primary objective is safety and feasibility, and secondary objectives are anti-tumor response (endpoints: overall response rate based on RECIST v 1.1 and irRECIST when feasible, progression-free survival and overall survival). Correlative endpoints include CAR T cell engraftment and persistence in peripheral blood and body fluids examined via quantitative PCR of CAR T DNA, and bioactivity of CAR T cells. Enrollment is ongoing.

Trial Registration

This trial is registered at ClinicalTrials.gov (NCT03585764).

Ethics Approval

This study was approved by the Institutional Review Board at the University of Pennsylvania (IRB 830111). All subjects provided written informed consent prior to any study-related procedures.

Personalized gene therapy locks out HIV, paving the way to control virus without antiretroviral drugs

INTRODUCTION

Advances in adoptive immunotherapy have enabled gene therapy approaches to be tested in clinical trials that involve the transfer of engineered immune cells to specifically target HIV-infected cells or block HIV infection or transmission. Genetic editing through engineered targeted nucleases provides a method for producing cells that are permanently resistant to HIV.

AREAS COVERED

Here, we discuss current and developing gene therapy approaches aimed to confer resistance to HIV infection at the cellular level by targeting viral or cellular elements, with a focus on gene editing strategies that target viral entry. Human gene therapy trials in HIV infection are reviewed.

EXPERT OPINION

In concept, a single infusion of genetically modified cells could potentially reduce the need for lifelong medication by providing long-term control over the virus (functional immunity). While the dream of completely eliminating viral reservoirs (sterilizing immunity) is appealing, this presents a significant additional hurdle and may not be necessary to improve long-term health. A single infusion, or a small number of infusions, of engineered cells may be shown in confirmatory clinical trials to produce a meaningful biologic effect. These techniques have implications for targeted gene therapy in HIV and other diseases.

Therapeutic immunization with EBNA-1 elicits responses to novel T cell epitopes in latently Lymphocryptovirus infected rhesus macaques (P4323)

Epstein-Barr virus (EBV) is a gamma-Herpesvirus associated with lymphoma or nasopharyngeal carcinoma in immunocompromised patients. Lymphocryptovirus (LCV) infection of rhesus macaques replicates several characteristics of the human EBV infection. EBNA-1 is a nuclear virus protein expressed in all phases of EBV/LCV infections, essential for survival, malignant transformation, tumor progression and escape from host immune response. In spite of its importance for viral replication and survival, EBNA-1 is poorly immunogenic during lytic or latent infection. However, since protection against select experimental infections was achieved after enhancement of antigen immunogenicity through immunization, we hypothesized that eliciting EBNA-1-specific responses during chronic latent infection could increase control of EBV/LCV in vivo. We therefore attempted to enhance and broaden LCV EBNA-1 responses via immunization with an AdC68-LCV-EBNA-1 vector in groups of rhesus macaques that were latently infected with LCV but exhibiting low baseline responses. Following immunization, several CD4+ and CD8+ T cell epitopes were identified through IFN-g ELISPOT assays either as novel or markedly expanded responses. One such novel expanded CD8+ T cell epitope was mapped to a 9-mer peptide restricted by Mamu B*029, and a tetramer was developed for staining of specific CD8+ T cells. The study provides proof of concept that EBNA-1 may be a suitable vaccine target.

Day-4 myeloid dendritic cells pulsed with whole tumor lysate are highly immunogenic and elicit potent anti-tumor responses

“Day-7” myeloid DCs are commonly used in the clinic. However, there is a strong need to develop DCs faster that have the same potent immunostimulatory capacity as “Day-7” myeloid DCs and at the same time minimizing time, labor and cost of DC preparations. Although “2 days” DCs can elicit peptide-specific responses, they have not been demonstrated to engulf, process and present complex whole tumor lysates, which could be more convenient and personalized source of tumor antigens than defined peptides. In this preclinical study, we evaluated the T-cell stimulatory capacity of Day-2, Day-4, and Day-7 cultured monocyte-derived DCs loaded with SKOV3 cell whole lysate prepared by freeze-thaw or by UVB-irradiation followed by freeze-thaw, and matured with lipopolysaccharide (LPS) and interferon (IFN)-gamma. DCs were evaluated for antigen uptake, and following maturation with LPS and IFN-gamma, DCs were assessed for expression of CD80, CD40, CD86, ICAM-1 and CCR7, production of IL-12p70 and IP-10, and induction of tumor-specific T-cell responses. Day-4 and Day-7 DCs exhibited similar phagocytic abilities, which were superior to Day-2 DCs. Mature Day-7 DCs expressed the highest CD40 and ICAM-1, but mature Day-4 DCs produced the most IL-12p70 and IP-10. Importantly, Day-4 and Day-7 DCs derived from ovarian cancer patients stimulated equally strongly tumor-specific T-cell responses. This is the first study demonstrating the highly immunogenic and strong T-cell stimulatory properties of Day-4 myeloid DCs, and provided important preclinical data for rapid development of potent whole tumor lysate-loaded DC vaccines that are applicable to many tumor types.

Abstract 2410: Development of a genetically-optimized whole tumor cell vaccine for ovarian cancer using HSV-derived glycoprotein D

Background: Dendritic cell (DC) vaccines offer a promising addition to standard treatment for ovarian cancer with surgery and chemotherapy. We have previously shown that treatment of whole tumor cells with replication-deficient herpes simplex virus (HSV) results in a potent, specific T-Cell response to ovarian tumors. We sought to improve vaccine efficiency by isolating and comparing two specific components of HSV-treated SK-OV-3-pulsed DCs: glycoprotein D (gD) and IL12p70.

Methods: SK-OV-3 cells were treated with HSV1716 or transfected with HSV-1-derived gD engineered to express a similar amount of surface of gD. We further engineered these cells to express IL12p70 by lentiviral transduction. Theses cells were UVB-irradiated and pulsed with DCs. ELISA was used to measure the kinetics of the IL12p70 burst of each tumor-pulsed DC, as well as to compare the naïve, autologous lymphocyte priming responses of each cell line.

Results: IL12p70 was increased 3-fold with gD-SKOV3 compared to HSV-SKOV3, while following the same kinetic curve (646 ± 45.2 pg/mL v. 234 ± 24.2 pg/mL; p <0.01). gD-SKOV3 also resulted in a 2-fold higher priming response. Both the IL12p70 burst and priming response were blocked by treatment of SKOV3-gD cells with an antibody to gD. With the addition of IL12 to these cells, SKOV3-gD, but not SKOV3-HSV cells, resulted in significantly higher and more prolonged IL12 burst than that of SKOV3-IL12 cells alone.

Conclusions: Our in vitro results suggest a synergistic effect of IL12p70 and gD that is not seen with infection by intact HSV-1. We have isolated two key components from HSV, cytokine stimulation and gD-mediated blockade of immunosuppression, that in combination result in a more potent, specific immune response to ovarian cancer tumor cells. We can now utilize these key components to engineer a more efficient whole tumor cell vaccine for EOC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2410.