Ana C. Parente-Pereira

Trafficking of CAR-Engineered Human T Cells Following Regional or Systemic Adoptive Transfer in SCID Beige Mice

Adoptive immunotherapy using chimeric antigen receptor-engrafted T cells is a promising emerging therapy for cancer. Prior to clinical testing, it is mandatory to evaluate human therapeutic cell products in meaningful in vivo pre-clinical models. Here, we describe the use of fused single-photon emission CT–CT imaging to monitor real-time migration of chimeric antigen receptor-engineered T cells in immune compromised (SCID Beige) mice. Following intravenous administration, human T cells migrate in a highly similar manner to that reported in man, but penetrate poorly into established tumors. By contrast, when delivered via intraperitoneal or subcutaneous routes, T cells remain at the site of inoculation with minimal systemic absorption—irrespective of the presence or absence of tumor. Together, these data support the validity of pre-clinical testing of human T-cell immunotherapy in SCID Beige mice. In light of their established efficacy, regional administration of engineered human T cells represents an attractive therapeutic option to minimize toxicity in the treatment of selected malignancies.

Preclinical In Vivo Modeling of Cytokine Release Syndrome Induced by ErbB-Retargeted Human T Cells: Identifying a Window of Therapeutic Opportunity?

The ErbB network is dysregulated in many solid tumors. To exploit this, we have developed a chimeric Ag receptor (CAR) named T1E28z that targets several pathogenetically relevant ErbB dimers. T1E28z is coexpressed with a chimeric cytokine receptor named 4αβ (combination termed T4), enabling the selective expansion of engineered T cells using IL-4. Human T4+ T cells exhibit antitumor activity against several ErbB+ cancer types. However, ErbB receptors are also expressed in several healthy tissues, raising concerns about toxic potential. In this study, we have evaluated safety of T4 immunotherapy in vivo using a SCID beige mouse model. We show that the human T1E28z CAR efficiently recognizes mouse ErbB+ cells, rendering this species suitable to evaluate preclinical toxicity. Administration of T4+ T cells using the i.v. or intratumoral routes achieves partial tumor regression without clinical or histopathologic toxicity. In contrast, when delivered i.p., tumor reduction is accompanied by dose-dependent side effects. Toxicity mediated by T4+ T cells results from target recognition in both tumor and healthy tissues, leading to release of both human (IL-2/IFN-γ) and murine (IL-6) cytokines. In extreme cases, outcome is lethal. Both toxicity and IL-6 release can be ameliorated by prior macrophage depletion, consistent with clinical data that implicate IL-6 in this pathogenic event. These data demonstrate that CAR-induced cytokine release syndrome can be modeled in mice that express target Ag in an appropriate distribution. Furthermore, our findings argue that ErbB-retargeted T cells can achieve therapeutic benefit in the absence of unacceptable toxicity, providing that route of administration and dose are carefully optimized.

Ovarian cancer immunotherapy using PD-L1 siRNA targeted delivery from folic acid-functionalized polyethylenimine: strategies to enhance T cell killing.

Adoptive T cell immunotherapy is a promising treatment strategy for epithelial ovarian cancer (EOC). However, programmed death ligand-1 (PD-L1), highly expressed on EOC cells, interacts with programmed death-1 (PD-1), expressed on T cells, causing immunosuppression. This study aims to block PD-1/PD-L1 interactions by delivering PD-L1 siRNA, using various folic acid (FA)-functionalized polyethylenimine (PEI) polymers, to SKOV-3-Luc EOC cells, and investigate the sensitization of the EOC cells to T cell killing. To enhance siRNA uptake into EOC cells, which over express folate receptors, PEI is modified with FA or PEG-FA so that siRNA is complexed into nanoparticles with folate molecules on the surface. PEI modification with a single functional group lowers the polymer cytotoxicity compared to unmodified PEI. FA-conjugated polymers increase siRNA uptake into SKOV-3-luc cells and decrease unspecific uptake into monocytes. All polymers result in 40% to 50% PD-L1 protein knockdown. Importantly, SKOV-3-Luc cells treated with either PEI-FA or PEI- polyethylene glycol (PEG)-FA/PD-L1 siRNA complexes are up to twofold more sensitive to T cell killing compared to scrambled siRNA treated controls. These findings are the first to demonstrate that PD-L1 knockdown in EOC cells, via siRNA/FA-targeted delivery, are able to sensitize cancer cells to T cell killing.

Synergistic Chemoimmunotherapy of Epithelial Ovarian Cancer Using ErbB-Retargeted T Cells Combined with Carboplatin

Epithelial ovarian cancer (EOC) remains the most lethal gynecologic malignancy, underscoring the need for better therapies. Adoptive immunotherapy using genetically targeted T cells represents a promising new treatment for hematologic malignancies. However, solid tumors impose additional obstacles, including the lack of suitable targets for safe systemic therapy and the need to achieve effective T cell homing to sites of disease. Because EOC undergoes transcœlomic metastasis, both of these challenges may be circumvented by T cell administration to the peritoneal cavity. In this study, we describe such an immunotherapeutic approach for EOC, in which human T cells were targeted against the extended ErbB family, using a chimeric Ag receptor named T1E28z. T1E28z was coexpressed with a chimeric cytokine receptor named 4αβ (combination termed T4), enabling the selective ex vivo expansion of engineered T cells using IL-4. Unlike control T cells, T4+ T cells from healthy donors and patients with EOC were activated by and destroyed ErbB+ EOC tumor cell lines and autologous tumor cultures. In vivo antitumor activity was demonstrated in mice bearing established luciferase-expressing SKOV-3 EOC xenografts. Tumor regression was accompanied by mild toxicity, manifested by weight loss. Although efficacy was transient, therapeutic response could be prolonged by repeated T cell administration. Furthermore, prior treatment with noncytotoxic doses of carboplatin sensitized SKOV-3 tumors to T4 immunotherapy, promoting enhanced disease regression using lower doses of T4+ T cells. By combining these approaches, we demonstrate that repeated administration of carboplatin followed by T4+ T cells achieved optimum therapeutic benefit in the absence of significant toxicity, even in mice with advanced tumor burdens.

Targeting of Aberrant αvβ6 Integrin Expression in Solid Tumors Using Chimeric Antigen Receptor-Engineered T Cells

Expression of the αvβ6 integrin is upregulated in several solid tumors. In contrast, physiologic expression of this epithelial-specific integrin is restricted to development and epithelial re-modeling. Here, we describe, for the first time, the development of a chimeric antigen receptor (CAR) that couples the recognition of this integrin to the delivery of potent therapeutic activity in a diverse repertoire of solid tumor models. Highly selective targeting αvβ6 was achieved using a foot and mouth disease virus-derived A20 peptide, coupled to a fused CD28+CD3 endodomain. To achieve selective expansion of CAR T cells ex vivo, an IL-4-responsive fusion gene (4αβ) was co-expressed, which delivers a selective mitogenic signal to engineered T cells only. In vivo efficacy was demonstrated in mice with established ovarian, breast, and pancreatic tumor xenografts, all of which express αvβ6 at intermediate to high levels. SCID beige mice were used for these studies because they are susceptible to cytokine release syndrome, unlike more immune-compromised strains. Nonetheless, although the CAR also engages mouse αvβ6, mild and reversible toxicity was only observed when supra-therapeutic doses of CAR T cells were administered parenterally. These data support the clinical evaluation of αvβ6 re-targeted CAR T cell immunotherapy in solid tumors that express this integrin.

Adoptive Immunotherapy of Epithelial Ovarian Cancer with Vγ9Vδ2 T Cells, Potentiated by Liposomal Alendronic Acid

Adoptive immunotherapy using γδ T cells harnesses their natural role in tumor immunosurveillance. The efficacy of this approach is enhanced by aminobisphosphonates such as zoledronic acid and alendronic acid, both of which promote the accumulation of stimulatory phosphoantigens in target cells. However, the inefficient and nonselective uptake of these agents by tumor cells compromises the effective clinical exploitation of this principle. To overcome this, we have encapsulated aminobisphosphonates within liposomes. Expanded Vγ9Vδ2 T cells from patients and healthy donors displayed similar phenotype and destroyed autologous and immortalized ovarian tumor cells, following earlier pulsing with either free or liposome-encapsulated aminobisphosphonates. However, liposomal zoledronic acid proved highly toxic to SCID Beige mice. By contrast, the maximum tolerated dose of liposomal alendronic acid was 150-fold higher, rendering it much more suited to in vivo use. When injected into the peritoneal cavity, free and liposomal alendronic acid were both highly effective as sensitizing agents, enabling infused γδ T cells to promote the regression of established ovarian tumors by over one order of magnitude. Importantly however, liposomal alendronic acid proved markedly superior compared with free drug following i.v. delivery, exploiting the “enhanced permeability and retention effect” to render advanced tumors susceptible to γδ T cell–mediated shrinkage. Although folate targeting of liposomes enhanced the sensitization of folate receptor–α+ ovarian tumor cells in vitro, this did not confer further therapeutic advantage in vivo. These findings support the development of an immunotherapeutic approach for ovarian and other tumors in which adoptively infused γδ T cells are targeted using liposomal alendronic acid.

Exploiting the Metal-Chelating Properties of the Drug Cargo for In Vivo Positron Emission Tomography Imaging of Liposomal Nanomedicines

The clinical value of current and future nanomedicines can be improved by introducing patient selection strategies based on noninvasive sensitive whole-body imaging techniques such as positron emission tomography (PET). Thus, a broad method to radiolabel and track preformed nanomedicines such as liposomal drugs with PET radionuclides will have a wide impact in nanomedicine. Here, we introduce a simple and efficient PET radiolabeling method that exploits the metal-chelating properties of certain drugs (e.g., bisphosphonates such as alendronate and anthracyclines such as doxorubicin) and widely used ionophores to achieve excellent radiolabeling yields, purities, and stabilities with 89Zr, 52Mn, and 64Cu, and without the requirement of modification of the nanomedicine components. In a model of metastatic breast cancer, we demonstrate that this technique allows quantification of the biodistribution of a radiolabeled stealth liposomal nanomedicine containing alendronate that shows high uptake in primary tumors and metastatic organs. The versatility, efficiency, simplicity, and GMP compatibility of this method may enable submicrodosing imaging studies of liposomal nanomedicines containing chelating drugs in humans and may have clinical impact by facilitating the introduction of image-guided therapeutic strategies in current and future nanomedicine clinical studies.

Intracavitary ‘T4 immunotherapy’ of malignant mesothelioma using pan-ErbB re-targeted CAR T-cells

Malignant mesothelioma remains an incurable cancer. We demonstrated that mesotheliomas expressed EGFR (79.2%), ErbB4 (49.0%) and HER2 (6.3%), but lacked ErbB3. At least one ErbB family member was expressed in 88% of tumors. To exploit ErbB dysregulation in this disease, patient T-cells were engineered by retroviral transduction to express a panErbB-targeted chimeric antigen receptor (CAR), co-expressed with a chimeric cytokine receptor that allows interleukin (IL)-4 mediated CAR T-cell proliferation. This combination is referred to as T4 immunotherapy. T-cells from mesothelioma patients were uniformly amenable to T4 genetic modification and expansion/enrichment thereafter using IL-4. Patient-derived T4+ T-cells were activated upon contact with a panel of four mesothelioma cell lines, leading to cytotoxicity and cytokine release in all cases. Adoptive transfer of T4 immunotherapy to SCID Beige mice with an established bioluminescent LO68 mesothelioma xenograft was followed by regression or eradication of disease in all animals. Despite the established ability of T4 immunotherapy to elicit cytokine release syndrome in SCID Beige mice, therapy was very well tolerated. These findings provide a strong rationale for the clinical evaluation of intracavitary T4 immunotherapy to treat mesothelioma.

CAR T-cell immunotherapy of MET-expressing malignant mesothelioma

ABSTRACT Mesothelioma is an incurable cancer for which effective therapies are required. Aberrant MET expression is prevalent in mesothelioma, although targeting using small molecule-based therapeutics has proven disappointing. Chimeric antigen receptors (CARs) couple the HLA-independent binding of a cell surface target to the delivery of a tailored T-cell activating signal. Here, we evaluated the anti-tumor activity of MET re-targeted CAR T-cells against mesothelioma. Using immunohistochemistry, MET was detected in 67% of malignant pleural mesotheliomas, most frequently of epithelioid or biphasic subtype. The presence of MET did not influence patient survival. Candidate MET-specific CARs were engineered in which a CD28+CD3ζ endodomain was fused to one of 3 peptides derived from the N and K1 domains of hepatocyte growth factor (HGF), which represents the minimum MET binding element present in this growth factor. Using an NIH3T3-based artificial antigen-presenting cell system, we found that all 3 candidate CARs demonstrated high specificity for MET. By contrast, these CARs did not mediate T-cell activation upon engagement of other HGF binding partners, namely CD44v6 or heparan sulfate proteoglycans, including Syndecan-1. NK1-targeted CARs demonstrated broadly similar in vitro potency, indicated by destruction of MET-expressing mesothelioma cell lines, accompanied by cytokine release. In vivo anti-tumor activity was demonstrated following intraperitoneal delivery to mice with an established mesothelioma xenograft. Progressive tumor regression occurred without weight loss or other clinical indicators of toxicity. These data confirm the frequent expression of MET in malignant pleural mesothelioma and demonstrate that this can be targeted effectively and safely using a CAR T-cell immunotherapeutic strategy.

Chemotherapy-induced apoptosis, autophagy and cell cycle arrest are key drivers of synergy in chemo-immunotherapy of epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is the most lethal of all gynecological malignancies in the UK. Recent evidence has shown that there is potential for immunotherapies to be successful in treating this cancer. We have previously shown the effective application of combinations of traditional chemotherapy and CAR (chimeric antigen receptor) T cell immunotherapy in in vitro and in vivo models of EOC. Platinum-based chemotherapy synergizes with ErbB-targeted CAR T cells (named T4), significantly reducing tumor burden in mice. Here, we show that paclitaxel synergizes with T4 as well, and look into the mechanisms behind the effectiveness of chemo-immunotherapy in our system. Impairment of caspase activity using pan-caspase inhibitor Z-VAD reveals this chemotherapy-induced apoptotic pathway as an essential factor in driving synergy. Mannose-6-phosphate receptor-mediated autophagy and the arrest of cell cycle in G2/M are also shown to be induced by chemotherapy and significantly contributing to the synergy. Increased expression of PD-1 on T4 CAR T cells occurred when these were in culture with ovarian tumor cells; on the other hand, EOC cell lines showed increased PD-L1 expression following chemotherapy treatment. These findings provided a rationale to look into testing PD-1 blockade in combination with paclitaxel and T4 immunotherapy. Combination of these three agents in mice resulted in significant reduction of tumor burden, compared to each treatment alone. In conclusion, the mechanism driving synergy in chemo-immunotherapy of EOC is multifactorial. A deeper understanding of such process is needed to better design combination therapies and carefully stratify patients.