Erratum: Immortalized human myoblast cell lines for the delivery of therapeutic proteins using encapsulated cell technology

[This corrects the article DOI: 10.1016/j.omtm.2022.07.017.].

Engineering a versatile and retrievable cell macroencapsulation device for the delivery of therapeutic proteins

Encapsulated cell therapy holds a great potential to deliver sustained levels of highly potent therapeutic proteins to patients and improve chronic disease management. A versatile encapsulation device that is biocompatible, scalable, and easy to administer, retrieve, or replace has yet to be validated for clinical applications. Here, we report on a cargo-agnostic, macroencapsulation device with optimized features for protein delivery. It is compatible with adherent and suspension cells, and can be administered and retrieved without burdensome surgical procedures. We characterized its biocompatibility and showed that different cell lines producing different therapeutic proteins can be combined in the device. We demonstrated the ability of cytokine-secreting cells encapsulated in our device and implanted in human skin to mobilize and activate antigen-presenting cells, which could potentially serve as an effective adjuvant strategy in cancer immunization therapies. We believe that our device may contribute to cell therapies for cancer, metabolic disorders, and protein-deficient diseases.

Abstract 2721: Sustained delivery of low-dose anti-CTLA-4 by genetically engineered encapsulated cells to the tumor microenvironment drives tumor response and prolongs survival in a colorectal cancer model

Introduction: Systemic therapy with CTLA-4 blocking antibody (aCTLA-4) restores endogenous antitumor immunity and induces remarkable long-term clinical benefits in patients with melanoma. Yet immune-related side effects remain a major hurdle to extending its label to many more types of cancer. Intra- and peritumoral administration of aCTLA-4 has recently emerged as a means to optimize its dose/efficacy ratio while preventing its off-target, systemic toxicities. Sustained peritumoral delivery of low-dose aCTLA-4 by genetically engineered encapsulated cells could offer a promising option for cancer treatment addressing the shortcomings of systemic therapy.

Material and Methods: The efficacy of sustained, low-dose aCTLA-4 delivered by genetically engineered encapsulated cells was assessed in human CTLA4 knock-in mice subcutaneously engrafted with MC38 colon adenocarcinoma cells. In a therapeutic model, mice were treated with either encapsulated human myoblast cells secreting aCTLA-4 (MVX-3) in the vicinity of the tumor, or i.p. injections of Ipilimumab (10mg/kg BIW x 4). Encapsulated wild-type cells (WT) and PBS were used as respective controls. A subgroup of mice was terminated at day 7 post-treatment for early pharmacological characterization. Tumor size and survival were measured to evaluate the efficacy. Secretion of aCTLA-4 by MVX-3 and aCTLA-4 titer in plasma was quantified by ELISA. Tumors, spleens, and draining lymph nodes were collected for flow cytometry analyses.

Results: Peritumoral administration of MVX-3 induced durable complete tumor rejection (2/7) and tumor growth control (4/7) when administered at doses 1’000 times lower than i.p ipilimumab, whereas rapid tumor growth without any tumor rejection was observed in mice treated with control vehicles. I.p. ipilimumab induced durable complete tumor rejection (9/12), while treatment-related toxicities upon dosing led to premature mice termination (3/12). MVX-3 was found as equally effective as i.p. ipilimumab in decreasing the proportion of CTLA4+ helper and regulatory T cells in the tumor at Day 7 post-treatment. Survival was also improved by MVX-3 compared to control vehicles.

Conclusions: These findings suggest that sustained delivery of low-dose aCTLA-4 by genetically engineered encapsulated cells to the tumor microenvironment could achieve similar therapeutic benefits as systemic therapy, without the commonly associated toxicities. The safety and biological efficacy profile of MVX-3 encourage further preclinical and clinical explorations.

Citation Format: Julien Grogg, Emily Charrier, Remi Vernet, Muriel Urwyler, Olivier Von Rohr, Valentin Saingier, Fabien Courtout, Aurelien Lathuiliere, Adrien Engel, Nicolas Mach. Sustained delivery of low-dose anti-CTLA-4 by genetically engineered encapsulated cells to the tumor microenvironment drives tumor response and prolongs survival in a colorectal cancer model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2721.

Immortalized human myoblast cell lines for the delivery of therapeutic proteins using encapsulated cell technology

Despite many promising results obtained in previous preclinical studies, the clinical development of encapsulated cell technology (ECT) for the delivery of therapeutic proteins from macrocapsules is still limited, mainly due to the lack of an allogeneic cell line compatible with therapeutic application in humans. In our work, we generated an immortalized human myoblast cell line specifically tailored for macroencapsulation. In the present report, we characterized the immortalized myoblasts and described the engineering process required for the delivery of functional therapeutic proteins including a cytokine, monoclonal antibodies and a viral antigen. We observed that, when encapsulated, the novel myoblast cell line can be efficiently frozen, stored, and thawed, which limits the challenge imposed by the manufacture and supply of encapsulated cell-based therapeutic products. Our results suggest that this versatile allogeneic cell line represents the next step toward a broader development and therapeutic use of ECT.

A Quantitative ELISA Protocol for Detection of Specific Human IgG against the SARS-CoV-2 Spike Protein

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a worldwide pandemic with at least 3.8 million deaths to date. For that reason, finding an efficient vaccine for this virus quickly became a global priority. The majority of vaccines now marketed are based on the SARS-CoV-2 spike protein that has been described as the keystone for optimal immunization. In order to monitor SARS-CoV-2 spike-specific humoral responses generated by immunization or infection, we have developed a robust and reproducible enzyme-linked immunosorbent assay (ELISA) protocol. This protocol describes a method for quantitative detection of IgG antibodies against the SARS-CoV-2 spike protein using antigen-coated microtiter plates. Results showed that antibodies could be quantified between the range of 1.953 ng/mL to 500 ng/mL with limited inter- and intra-assay variability.

MVX-ONCO-1 in advanced refractory cancers: Safety, feasibility, and preliminary efficacy results from all HNSCC patients treated in two ongoing clinical trials

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Background: MVX-ONCO-1 is an active, personalized cancer immunotherapy combining irradiated autologous tumor cells and encapsulated, genetically engineered allogeneic cells producing GM-CSF. The immunostimulant cytokine is released locally in a sustained manner over one week at the immunization site. All cancer types are potential candidates and more than 40 patients have been treated in two clinical trials. Here we report the data on all HNSCC patients treated, as of 31st January 2021. Methods: Eleven (11) patients with locally advanced/metastatic HNSCC relapsing after at least one line of systemic therapy were enrolled in 2 open-label, single-arm clinical trials (NCT02193503 and NCT02999646) evaluating the safety, feasibility and efficacy of MVX-ONCO-1. All patients were treated with at least 5 administrations of MVX-ONCO-1 over 8 weeks (W1,2,3,4,6,8). Each administration consists of the subcutaneous implantation in healthy skin of 2 capsules containing each 8x105 cells, producing > 20ng/24h of GM-CSF, and an injection of 4x106 irradiated autologous tumor cells between the 2 capsules. Results: Eleven (11) patients are evaluable for safety and feasibility. Ten patients (91%) with at least 6 months, respectively 9 patients (82%) with 12 months follow-up are evaluable for efficacy analysis. Eight patients (80%) failed both Cisplatin based chemotherapy and anti-PD1 therapies prior to enrolment. The most common treatment-related adverse event (AE) was local hematoma at implantation site in 3 patients (27%). None experienced > grade 2 treatment-related AE. Overall Survival is 70% (7/10pts) at 6 months, and 56% (5/9pts) at 12 months. Eight patients (80%) presented some degree of disease control with 4SDs, 2PRs and 2CRs. Both CRs are longstanding, with both patients not any longer on anticancer therapy for 24 and 6 months respectively. While 1 PR was observed on MVX-ONCO-1, 1PR and 1CR were observed on subsequent Nivolumab therapy (both CPS0), and 1 CR was observed after carboplatin-cetuximab. Two patients had progressive disease as best overall response. Conclusions: Treatment with MVX-ONCO-1 is feasible, safe and well tolerated. Preliminary efficacy data shows an encouraging rate of tumor control including prolonged CR in patients subsequently treated with nivolumab or chemotherapy. Efficacy of the concurrent use of anti-PD-1 and MVX-ONCO will be assessed in a planned clinical trial. Clinical trial information: NCT02999646.

Local Sustained GM-CSF Delivery by Genetically Engineered Encapsulated Cells Enhanced Both Cellular and Humoral SARS-CoV-2 Spike-Specific Immune Response in an Experimental Murine Spike DNA Vaccination Model

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a worldwide pandemic with recurrences. Therefore, finding a vaccine for this virus became a priority for the scientific community. The SARS-CoV-2 spike protein has been described as the keystone for viral entry into cells and effective immune protection against SARS-CoV-2 is elicited by this protein. Consequently, many commercialized vaccines focus on the spike protein and require the use of an optimal adjuvant during vaccination. Granulocyte-macrophage colony-stimulating factor (GM-CSF) has demonstrated a powerful enhancement of acquired immunity against many pathogens when delivered in a sustained and local manner. In this context, we developed an encapsulated cell-based technology consisting of a biocompatible, semipermeable capsule for secretion of GM-CSF. In this study, we investigated whether murine GM-CSF (muGM-CSF) represents a suitable adjuvant for SARS-CoV-2 immunization, and which delivery strategy for muGM-CSF could be most beneficial. To test this, different groups of mice were immunized with intra-dermal (i.d.) electroporated spike DNA in the absence or presence of recombinant or secreted muGM-CSF. Results demonstrated that adjuvanting a spike DNA vaccine with secreted muGM-CSF resulted in enhancement of specific cellular and humoral immune responses against SARS-CoV-2. Our data also highlighted the importance of delivery strategies to the induction of cellular and humoral-mediated responses.