In vitro transcribed mRNA constitutes a versatile platform to encode antigens and to evoke CD8 T-cell responses. Systemic delivery of mRNA packaged into cationic liposomes (lipoplexes) has proven ...particularly powerful in achieving effective antitumor immunity in animal models. Yet, T-cell responses to mRNA lipoplexes critically depend on the induction of type I interferons (IFN), potent pro-inflammatory cytokines, which inflict dose-limiting toxicities. Here, we explored an advanced hybrid lipid polymer shell mRNA nanoparticle (lipopolyplex) endowed with a trimannose sugar tree as an alternative delivery vehicle for systemic mRNA vaccination. Like mRNA lipoplexes, mRNA lipopolyplexes were extremely effective in conferring antitumor T-cell immunity upon systemic administration. Conversely to mRNA lipoplexes, mRNA lipopolyplexes did not rely on type I IFN for effective T-cell immunity. This differential mode of action of mRNA lipopolyplexes enabled the incorporation of N1 methyl pseudouridine nucleoside modified mRNA to reduce inflammatory responses without hampering T-cell immunity. This feature was attributed to mRNA lipopolyplexes, as the incorporation of thus modified mRNA into lipoplexes resulted in strongly weakened T-cell immunity. Taken together, we have identified lipopolyplexes containing N1 methyl pseudouridine nucleoside modified mRNA as potent yet low-inflammatory alternatives to the mRNA lipoplexes currently explored in early phase clinical trials.
mRNA vaccines have recently proved to be highly effective against SARS-CoV-2. Key to their success is the lipid-based nanoparticle (LNP), which enables efficient mRNA expression and endows the ...vaccine with adjuvant properties that drive potent antibody responses. Effective cancer vaccines require long-lived, qualitative CD8 T cell responses instead of antibody responses. Systemic vaccination appears to be the most effective route, but necessitates adaptation of LNP composition to deliver mRNA to antigen-presenting cells. Using a design-of-experiments methodology, we tailored mRNA-LNP compositions to achieve high-magnitude tumor-specific CD8 T cell responses within a single round of optimization. Optimized LNP compositions resulted in enhanced mRNA uptake by multiple splenic immune cell populations. Type I interferon and phagocytes were found to be essential for the T cell response. Surprisingly, we also discovered a yet unidentified role of B cells in stimulating the vaccine-elicited CD8 T cell response. Optimized LNPs displayed a similar, spleen-centered biodistribution profile in non-human primates and did not trigger histopathological changes in liver and spleen, warranting their further assessment in clinical studies. Taken together, our study clarifies the relationship between nanoparticle composition and their T cell stimulatory capacity and provides novel insights into the underlying mechanisms of effective mRNA-LNP-based antitumor immunotherapy.
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Using design-of experiments methodology, mRNA-lipid-based nanoparticle compositions conferring strong antitumor CD8 T cell responses after systemic administration were identified. Increased immunogenicity depended on mRNA expression by splenic antigen-presenting cells and induction of type I interferon. The study provides novel insights into the underlying mechanisms of effective mRNA-based antitumor immunotherapy.
Improved understanding of cancer immunology has provided insight into the phenomenon of frequent tumor recurrence after initially successful immunotherapy. A delicate balance exists between the ...capacity of the immune system to control tumor growth and various resistance mechanisms that arise to avoid or even counteract the host's immune system. These resistance mechanisms include but are not limited to (i) adaptive expression of inhibitory checkpoint molecules in response to the proinflammatory environment and (ii) amplification of cancer stem cells, a small fraction of tumor cells possessing the capacity for self‐renewal and mediating treatment resistance and formation of metastases after long periods of clinical remission. Several individual therapeutic agents have so far been developed to revert T‐cell exhaustion or disrupt the cross‐talk between cancer stem cells and the tumor‐promoting microenvironment. Here, we demonstrate that a three‐arm combination therapy—consisting of an mRNA‐based vaccine to induce antigen‐specific T‐cell responses, monoclonal antibodies blocking inhibitory checkpoint molecules (PD‐1, TIM‐3, LAG‐3), and antibodies targeting IL‐6 and TGF‐β—improves the therapeutic outcome in subcutaneous TC‐1 tumors and significantly prolongs survival of treated mice. Our findings point to a need for a rational development of multidimensional anticancer therapies, aiming at the induction of tumor‐specific immunity and simultaneously targeting multiple resistance mechanisms.
What's new?
Tumors can become resistant to immunotherapy via multiple mechanisms, necessitating a search for new therapeutic approaches to combat recurrent tumor disease. Here, single combination therapy of an mRNA vaccine with inhibitors of either immune checkpoint molecules or the IL‐6/TGF‐β pathway was investigated in a TC‐1 tumor cell mouse model. The combination of mRNA vaccine with either of the other agents showed limited therapeutic efficacy in a long‐established TC‐1 tumor model. By contrast, the three approaches together—IL‐6/TGF‐β pathway disruption, concurrent blockade of three different immune checkpoint molecules, and mRNA‐based anticancer immunotherapy—significantly improved therapeutic control of long‐established tumors.
Messenger RNA (mRNA) has emerged as a promising therapeutic modality for various diseases. However, efficient delivery of mRNA into target cells remains a significant challenge. In this study, the ...combinatorial synthesis and characterization of a novel series of ionizable biscarbamate lipids (IBLs) for mRNA lipid nanoparticle (LNP) delivery are reported. A simplified and scalable method is developed, resulting in IBLs suitable for formulating mRNA into stable LNPs. Two generations of IBLs are synthesized and evaluated for their mRNA transfection capacity in vitro, using eGFP as a reporter protein, leading to the identification of S‐Ac7‐DOG as a lead IBL. Upon intramuscular vaccination, S‐Ac7‐DOG LNPs instigated robust antigen‐specific CD8+ T cell responses against an mRNA encoded viral oncoprotein and a tumor neo‐antigen. In comparison to MC3 LNPs, which are used as a benchmark, S‐Ac7‐DOG LNPs exhibit low reactogenicity, robust mRNA transfection, and a distinct biodistribution, with higher accumulation in draining lymph nodes and spleen. These findings highlight the potential of IBLs as a novel and promising class of ionizable lipids for mRNA delivery in vaccines and beyond.
This study reports on combinatorial synthesis of ionizable biscarbamate lipids (IBLs) for mRNA lipid nanoparticle (LNP) delivery. In vitro screenings identify S‐Ac7‐DOG as a lead IBL, with high mRNA transfection capacity. In vivo, S‐Ac7‐DOG mRNA LNPs combine low reactogenicity with high local transfection. S‐Ac7‐DOG LNPs encapsulating mRNA encoding for tumor antigen can mount protective T cell responses against a tumor challenge.
Improved understanding of cancer immunology has provided insight into the phenomenon of frequent tumor recurrence after initially successful immunotherapy. A delicate balance exists between the ...capacity of the immune system to control tumor growth and various resistance mechanisms that arise to avoid or even counteract the host's immune system. These resistance mechanisms include but are not limited to (
i
) adaptive expression of inhibitory checkpoint molecules in response to the proinflammatory environment and (
ii
) amplification of cancer stem cells, a small fraction of tumor cells possessing the capacity for self‐renewal and mediating treatment resistance and formation of metastases after long periods of clinical remission. Several individual therapeutic agents have so far been developed to revert T‐cell exhaustion or disrupt the cross‐talk between cancer stem cells and the tumor‐promoting microenvironment. Here, we demonstrate that a three‐arm combination therapy—consisting of an mRNA‐based vaccine to induce antigen‐specific T‐cell responses, monoclonal antibodies blocking inhibitory checkpoint molecules (PD‐1, TIM‐3, LAG‐3), and antibodies targeting IL‐6 and TGF‐β—improves the therapeutic outcome in subcutaneous TC‐1 tumors and significantly prolongs survival of treated mice. Our findings point to a need for a rational development of multidimensional anticancer therapies, aiming at the induction of tumor‐specific immunity and simultaneously targeting multiple resistance mechanisms.
What's new?
Tumors can become resistant to immunotherapy via multiple mechanisms, necessitating a search for new therapeutic approaches to combat recurrent tumor disease. Here, single combination therapy of an mRNA vaccine with inhibitors of either immune checkpoint molecules or the IL‐6/TGF‐β pathway was investigated in a TC‐1 tumor cell mouse model. The combination of mRNA vaccine with either of the other agents showed limited therapeutic efficacy in a long‐established TC‐1 tumor model. By contrast, the three approaches together—IL‐6/TGF‐β pathway disruption, concurrent blockade of three different immune checkpoint molecules, and mRNA‐based anticancer immunotherapy—significantly improved therapeutic control of long‐established tumors.
Pregnancy- and lactation-associated osteoporosis (PLO) is a rare form of osteoporosis, of which the pathogenesis and best treatment options are unclear. In this report, we describe the case of a ...34-year old woman diagnosed with severe osteoporosis and multiple vertebral fractures after her first pregnancy, who was subsequently treated with teriparatide (TPTD) and zoledronic acid (ZA). We describe the clinical features, imaging examination, and genetic analysis. Substantial improvements were observed in areal and volumetric bone mineral density (BMD), microarchitecture, and strength between 7 and 40 months postpartum as assessed by dual-energy X-ray absorptiometry at the total hip and spine and by high-resolution peripheral quantitative CT at the distal radius and tibiae. At the hip, spine, and distal radius, these improvements were mainly enabled by treatment with TPTD and ZA, while at the distal tibiae, physiological recovery and postpartum physiotherapy due to leg pain after stumbling may have played a major role. Additionally, the findings show that, despite the improvements, BMD, microarchitecture, and strength remained severely impaired in comparison with healthy age- and gender-matched controls at 40 months postpartum. Genetic analysis showed no monogenic cause for osteoporosis, and it is suggested that PLO in this woman could have a polygenic origin with possible susceptibility based on familiar occurrence of osteoporosis.
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