Lipid nanoparticles delivering constitutively active STING mRNA as a novel anti-cancer therapeutic approach

Treating immunosuppressive tumors represents a major challenge in cancer therapies. Activation of STING signaling has shown remarkable potential to invigorate the immunologically 'cold' tumor microenvironment (TME). However, we and others have shown that STING is silenced in many cancers, including pancreatic ductal adenocarcinoma (PDAC) and Merkel cell carcinoma (MCC), both of which are associated with an immune-dampened TME. In this study, we applied mRNA lipid nanoparticles (LNP) to deliver a permanently active gain-of-function STINGR284S mutant into PDAC and MCC cells. Expression of STINGR284S induces cytokines and chemokines crucial for promoting intratumoral infiltration of CD8+ T cells and, importantly, also leads to robust cancer cell death while avoiding T cell entry and toxicity. Our studies demonstrated that mRNA-LNP delivery of STINGR284S could be explored as a novel therapeutic tool to reactivate antitumor response in an array of STING-deficient cancers while overcoming the toxicity and limitations of conventional STING agonists.

Modern possibilities of therapy for primary cutaneous T-cell lymphomas: the first results of the use of brentuximab vedotin in the Russian Federation

Background. Primary cutaneous T-cell lymphomas are rare heterogeneous group of lymphoproliferative diseases characterized by primarily involving skin and subcutaneous adipose tissue. Half of these cases are mycosis fungoides (MF), for about 25% are cutaneous CD30+ lymphoproliferative diseases (CD30+ LPD): primary cutaneous anaplastic large cell lymphoma (pcALCL) and lymphomatoid papulosis (LyP). During the initiating treatment of patients with MF and Szary syndrome (SS), carried out on the territory of the Russian Federation, for about 30% of patients are resistant to various therapeutic effects, especially in the later stages. The problem of the treatment of CD30+ LPD is extracutaneous dissemination in case of pcALCL, steadily relapsing course of LyP without symptom-free intervals. These characteristics of the therapy of cutaneous lymphomas demand for the need to search for new treatment options. Brentuximab vedotin, according to the results of the international randomized ALCANZA trial, has shown high efficiency in the treatment of cutaneous T-cell lymphoproliferative diseases. Aim. To evaluate the efficacy of brentuximab vedotin application in patients with cutaneous T-cell lymphomas in adverse risk group received at least one line of systemic therapy. Materials and methods. The study included 21 patients: 16 men and 5 women. The diagnosis of MF was verified in 8 patients, SS in 5 patients, cutaneous CD30+ LPD in 6 patients (5 patients pcALCL, 1 patient LyP) and a primary cutaneous peripheral T-cell lymphoma, unspecified in 2 patients. The diagnosis of cutaneous T-cell lymphoma was verified on the basis of the anamnesis of the disease, on the character of cutaneous lesions, on histological, immunohistochemical and in some cases on molecular genetic testing of the biopted sample of the skin (the assessment of T-cell receptor gene rearrangement). Results. The late stages of the disease were diagnosed in 12 of 13 patients with MF/SS. Extracutaneous lesions were diagnosed in 57% of cases. The median of prior lines therapy was 3 (18 variants of treatment). The overall response to the treatment was achieved in 91% of cases (in 19 of 21 patients): the complete remission was obtained in 53% of cases, very good partial remission in 31% of cases and partial remission in 16% of cases. The progression of the disease was determined in 2 patients (after the first and fourth cycles). Some patients with partial remission as a result of therapy using brentuximab vedotin had the additional therapy (radiation therapy, interferon , the cycles of systemic therapy) and these acts gave an option of achieving deeper antitumor response. The early relapse was diagnosed in 2 of 19 patients who had responded to the treatment. The treatment tolerability was acceptable, and the toxicity did not exceed the already known one described in earlier studies. Thus, the stable overall antitumor response had been persisting in 89% of patients (the median of the observation was 10 months). Conclusion. The use of targeted therapy with brentuximab vedotin gave an option of achieving high treatment results in group of patients with advanced stages of the disease and inefficiency of several lines of therapy.

Interventional Radiology Image-Guided Locoregional Therapies (LRTs) and Immunotherapy for the Treatment of HCC

Image-guided locoregional therapies (LRTs) are a crucial asset in the treatment of hepatocellular carcinoma (HCC), which has proven to be characterized by an impaired antitumor immune status. LRTs not only directly destroy tumor cells but also have an immunomodulating role, altering the tumor microenvironment with potential systemic effects. Nevertheless, the immune activation against HCC induced by LRTs is not strong enough on its own to generate a systemic significant antitumor response, and it is incapable of preventing tumor recurrence. Currently, there is great interest in the possibility of combining LRTs with immunotherapy for HCC, as this combination may result in a mutually beneficial and synergistic relationship. On the one hand, immunotherapy could amplify and prolong the antitumoral immune response of LRTs, reducing recurrence cases and improving outcome. On the other hand, LTRs counteract the typical immunosuppressive HCC microenvironment and status and could therefore enhance the efficacy of immunotherapy. Here, after reviewing the current therapeutic options for HCC, we focus on LRTs, describing for each of them the technique and data on its effect on the immune system. Then, we describe the current status of immunotherapy and finally report the recently published and ongoing clinical studies testing this combination.

Effect of MAGE-C1 Gene Expression on Prognosis and Effectiveness of Bortezomib-Containing Courses in Multiple Myeloma

Introduction. The group of genes, encoding cancer-testis antigens is actively studied as a new markers of refractory in some diseases, including multiple myeloma (MM). It is suggested that the MAGE-C1 gene in MM may be considered as an additional marker predicting the effectiveness of therapy. Purpose. Determine of MAGE-C1 gene expression by quantitative real-time polymerase chain reaction (qRT-PCR) in MM patients and assess the correlation of expression with some laboratory parameters and response on bortezomib-containing therapy. Patients and methods. A prospective study from February 2019 to July 2021 included 76 MM patients (43 men and 33 women) aged 35 to 82 years (median 58). The level of MAGE-C1 gene expression by qPCR-PCR in bone marrow samples, enriched with CD138+ cells, was determined for all patients. Quantity of MAGE-C1 expression was calculated with 2ΔCt method relative to housekeeping gene expression. Plasma cell content ranged from 1 to 89% (median 26%), monoclonal paraprotein secretion vary from 2.1 to 82.1 g/l, Bence-Jones protein in urine (from trace values to 12.54 g/day) was determined in 50 patients. High - risk cytogenetic [t(4; 14)(p16; q32), del17p] was documented in 22 patients, bone plasmocytomas - in 36 patients, myeloma nephropathy - in 17. All patients recieved induction with bortezomib - containing courses. Median follow-up duration: 14 months (1-22 months). As a control, similar bone marrow cells of 7 healthy donors were investigated. Results. The average value of MAGE-C1 expression in donors was 0.01 ± 0.007, a range of values vary from 0.0003 to 0.06. Gene expression MAGE-C1 index > 0.06 is accepted as increased expression. High serum lactate dehydrogenase (LDH) level (higher than the upper limit of reference values) was observed in patients with high MAGE-C1 gene expression [median - 0.35], normal LDH-level (≤ 260 U/L) was observed in patients with lower MAGE-C1 gene expression [median - 0.04]; p < 0.0001 (Figure 1). Negative correlation was found between the content of hemoglobin (Hb) and level of MAGE-C1 expression: Hb ≥ 12.0 g/dl was observed in patients with increased MAGE-C1 expression [median - 0.27], and Hb 5.5-11.8 g/dl - in patients with lower expression indices [median 0.1]; p=0,034. Antitumor response was evaluated after induction therapy in 51 patients. In 100% of patients with MAGE-C1 expression of ≤ 0.06 ≥ partial response (PR) was achieved, while in patients with MAGE-C1 expression of 0.07-1.0 ≥ PR was achieved in 84.6% of cases, and in patients with MAGE-C1 expression of > 1.0 - in 58%; p > 0.05. Besides, patients with ≥ PR had a level of MAGE-C1 expression lower than patients with a refractory to bortezomib [median 0.17 vs 1.14]; p = 0.04 (Figure 2). Conclusions. High MAGE-C1 gene expression in MM patients is associated with an increase in LDH, which corresponds to stage III by R-ISS. Probability of achievement of the antitumor response ≥ PR on the bortezomib-containing induction is reliable above at patients with low MAGE-C1 expression while the hyperexpression of this gene is followed by a refractory to a bortezomib therapy. Further study of MAGE-C1 gene expression may promote a personalized approach in the choice of antitumor therapy. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

432 Nemvaleukin alfa, a novel engineered IL-2 cytokine, in combination with the anti-PD-1 antibody pembrolizumab in patients with recurrent/metastatic head and neck squamous cell carcinoma (ION-01 study)

BackgroundNemvaleukin alfa (nemvaleukin, ALKS 4230) is a novel engineered cytokine that selectively binds to the intermediate-affinity IL-2R to preferentially activate and expand anti-tumor CD8+ T and NK cells with minimal expansion of regulatory T cells (Treg), thereby leveraging antitumor effects of the IL-2 pathway while mitigating potential toxicity that limits use.1 Nemvaleukin single-agent activity has been demonstrated in checkpoint inhibitor-experienced patients, and deep and durable responses have been achieved in combination with pembrolizumab in multiple tumor types (eg, breast, head and neck, gastrointestinal, genitourinary, gynecological).2MethodsION-01 (NCT04144517) is a nonrandomized trial in adult patients with histologically/cytopathologically confirmed diagnosis of metastatic/recurrent head and neck squamous cell carcinoma. Eligible patients have progressive disease after ≥8 weeks on anti-PD-(L)1 therapy. The primary endpoint is the rate of new or improved antitumor response after the addition of nemvaleukin. Secondary objectives include characterization of the antitumor response and evaluation of safety and tolerability of the combination regimen. Patients receive intravenous nemvaleukin (3 μg/kg) once daily for the first 5 days and pembrolizumab (200 mg) on day 1 of each 21-day cycle. Tumor imaging and biopsies were performed at baseline and at pre-specified times. We present preliminary safety and antitumor activity (RECIST v1.1) data as of June 2021.ResultsFourteen patients with progressive disease received combination therapy with nemvaleukin and pembrolizumab; 8 had no prior response to pembrolizumab, 6 had previous best response of stable disease or partial response. Mean (± SD) age was 62 ± 12 years, 86% were male, and all were Caucasian. Prior anti-cancer therapy included radiotherapy (93%) and surgery (50%). ECOG performance status was 0 (14%) and 1 (86%) at baseline. Treatment-related adverse events of any grade in ≥30% of patients were chills (64.3%), pyrexia (57.1%), fatigue (42.9%), and nausea (35.7%). Five patients had stable disease as best response. One patient achieved a partial response (complete response in the target lesion) and remains on treatment (8+ cycles). Expansion of CD8+ T and NK cells with minimal Treg expansion was observed.ConclusionsNemvaleukin and pembrolizumab combination therapy was generally well tolerated; adverse events were consistent with those observed with intravenous nemvaleukin in ARTISTRY studies [2]. Peripheral immune cell expansion profiles are comparable to that observed with the same regimen in the ARTISTRY 1 phase 1 study. Emerging data from pretreatment and on-treatment paired biopsies will further characterize specific antitumor effects of nemvaleukin and pembrolizumab in this patient population.AcknowledgementsThe authors would like to thank all the patients who are participating in this study and their families. The study is sponsored by Alkermes, Inc. Medical writing and editorial support was provided by Parexel, and funded by Alkermes, Inc.Trial RegistrationClinicalTrials.gov NCT04144517ReferencesLopes JE, Fisher JL, Flick HL, et al. ALKS 4230: a novel engineered IL-2 fusion protein with an improved cellular selectivity profile for cancer immunotherapy. J Immunother Cancer 2020;8:e000673. doi: 10.1136/jitc-2020-000673.Boni V, Winer IS, Gilbert L, et al. ARTISTRY-1: Nemvaleukin alfa monotherapy and in combination with pembrolizumab in patients (pts) with advanced solid tumors. J Clin Oncol 2021;39(Suppl 15):abstr 2513.Ethics ApprovalThis study was approved by Quorum Review IRB (now Advarra IRB), approval number QR 33752.

PENTOXIFYLLINE ENHANCES IN VITRO T-CELL ANTITUMOR RESPONSE IN BREAST CANCER PATIENTS

The NF-κB transcription factor controls the expression of genes responsible for cell cycle, apoptosis, and other immunoregulatory functions. Some nonspecific NF-κB inhibitors were found after discovering the possibility of blocking tumor growth through suppression of NF-κB activity, but their use was complicated by multiple side effects, such as interleukin-1β-related systemic inflammation or non-immunerelated complications, which may be due to inhibition of the p65 NF-κB subunit that plays a central role in organogenesis and inflammation. Inhibition of the c-Rel subunit leads to tumor growth restriction by modulating the T-regulatory cell activity.In 2017, Grinberg-Bleyer and co-authors checked the hypothesis that selective inhibition of the c-Rel subunit can be performed using pentoxifylline and will effectively regulate Treg activity during tumor growth. The authors showed that pentoxphylline, an FDA-approved drug, could indeed induce selective degradation of c-Rel without affecting p65, and suggested that such an effect could be effective in suppressing tumor growth. In this regard, we aimed to investigate in vitro how pentoxifylline affect the functional activity and antitumor cytotoxic potential of T-cells in cancer patients.The objects of the study were peripheral blood mononuclear cells from 25 patients with primary breast cancer (no metastases), 15 patients with metastatic breast cancer, and 25 healthy women without breast pathology. Informed consent was obtained from all donors and patients. The study was approved by the local ethics committee.Here we showed that pentoxifylline treatment in vitro enhances the pro-apoptotic and cytotoxic antitumor response via increasing the expression of TRAIL on T-lymphocytes, mainly in healthy donors and patients with metastatic breast cancer, both on intact T-cells and in response to the cells of the tumor line of human breast carcinoma ZR-75-1. In healthy donors, in the presence of pentoxifylline, a population of highly expressing TRAIL CD4 and CD8 T-cells appears.

Semi-mechanistic Model for the Antitumor Response of a Combination Cocktail of Immuno-Modulators in Non-inflamed (Cold) Tumors

Immune checkpoint inhibitors, administered as single agents, have demonstrated clinical efficacy. However, when treating cold tumors, different combination strategies are needed. This work aims to develop a semi-mechanistic model describing the antitumor efficacy of immunotherapy combinations in cold tumors. Tumor size of mice treated with TC-1/A9 non-inflamed tumors and the drug effects of an antigen, a toll-like receptor-3 agonist (PIC), and an immune checkpoint inhibitor (anti-programmed cell death 1 antibody) were modeled using Monolix and following a middle-out strategy. Tumor growth was best characterized by an exponential model with an estimated initial tumor size of 19.5 mm3 and a doubling time of 3.6 days. In the treatment groups, contrary to the lack of response observed in monotherapy, combinations including the antigen were able to induce an antitumor response. The final model successfully captured the 23% increase in the probability of cure from bi-therapy to triple-therapy. Moreover, our work supports that CD8+ T lymphocytes and resistance mechanisms are strongly related to the clinical outcome. The activation of antigen-presenting cells might be needed to achieve an antitumor response in reduced immunogenic tumors when combined with other immunotherapies. These models can be used as a platform to evaluate different immuno-oncology combinations in preclinical and clinical scenarios.

Novel potent anti-STEAP1 bispecific antibody to redirect T cells for cancer immunotherapy

BackgroundThe prognosis for metastatic Ewing sarcoma family of tumors (EFT) is still poor despite high-dose chemotherapy and radiation treatment. Immunotherapies hold promise, but cancer antigen-targeting immunotherapies have largely failed to induce effective T cell receptor-mediated antitumor response. However, T cell-engaging bispecific antibodies (T-BsAbs) have yet to be adequately explored.MethodsRehumanized STEAP1-IgG was used to build T-BsAb (named BC261) using the 2+2 IgG-[L]-scFv platform carrying the anti-CD3 huOKT3 scFv as the second specificity. Its binding epitope mapping, species cross-reactivity, tumor cell line staining, and in vitro cytotoxicity were investigated thoroughly. Its potency in driving tumor-infiltrating lymphocytes (TILs) was quantified using bioluminescence, correlated with in vivo antitumor response against cell line-derived or patient-derived xenografts (CDXs or PDXs) and compared with anti-STEAP1 T-BsAbs built on representative antibody platforms.ResultsBC261 binding epitope was mapped to its second extracellular domain of STEAP1 shared among canine and primate orthologs. BC261 induced potent cytotoxicity against panels of EFT, prostate cancer, and canine osteosarcoma cell lines despite their low antigen density. BC261 drove significantly more TILs into tumors (30-fold) and exerted superior antitumor effects compared with the other standard BsAb platforms. The antitumor efficacy of BC261 was consistent against EFT and prostate cancer CDXs and PDXs.ConclusionsBC261 was highly efficient in driving T cell infiltration and tumor ablation. Either as stand-alone therapeutics or for ex vivo armed T cells, this novel anti-STEAP1 T-BsAb BC261 has therapeutic potential.