Advancements in cell membrane camouflaged nanoparticles: A bioinspired platform for cancer therapy.

Cancer is still a major disease that is currently difficult for humans to overcome. When the expression of the cluster of differentiation 47 (CD47) is upregulated, tumor cells interact with the macrophage inhibitory receptor signal regulatory protein α (SIRPα) to transmit the "Don't eat me" signal, thereby avoiding phagocytosis by the macrophages. Therefore, when the CD47-SIRPα axis is inhibited, the macrophages' phagocytic function can be restored and can also exert antitumor effects. This Review mainly introduces recent advances in tumor therapy targeted on the CD47-SIRPα axis, including the antibody and fusion protein, small molecule, gene therapy, cell therapy, and drug delivery system, to inhibit the function of CD47 expressed on tumor cells and promote tumor phagocytosis by macrophages. In addition, this Review also summarizes the current approaches to avoid anemia, a common side effect of CD47-SIRPα inhibitions, and provides ideas for clinical transformation.

Recent Advances of Tumor Therapy Based on the CD47-SIRPα Axis.

Simple Summary Immunotherapy aims to engage various immune cells in the elimination of cancer cells. Neutrophils are the most abundant leukocytes in the circulation and have unique mechanisms by which they can kill cancer cells opsonized by antibodies. However, neutrophil effector functions are limited by the inhibitory receptor SIRPα, when it interacts with CD47. The CD47 protein is expressed on all cells in the body and acts as a ‘don’t eat me’ signal to prevent tissue damage. Cancer cells can express high levels of CD47 to circumvent tumor elimination. Thus, blocking the interaction between CD47 and SIRPα may enhance anti-tumor effects by neutrophils in the presence of tumor-targeting monoclonal antibodies. In this review, we discuss CD47-SIRPα as an innate immune checkpoint on neutrophils and explore the preliminary results of clinical trials using CD47-SIRPα blocking agents. Abstract In the past 25 years, a considerable number of therapeutic monoclonal antibodies (mAb) against a variety of tumor-associated antigens (TAA) have become available for the targeted treatment of hematologic and solid cancers. Such antibodies opsonize cancer cells and can trigger cytotoxic responses mediated by Fc-receptor expressing immune cells in the tumor microenvironment (TME). Although frequently ignored, neutrophils, which are abundantly present in the circulation and many cancers, have demonstrated to constitute bona fide effector cells for antibody-mediated tumor elimination in vivo. It has now also been established that neutrophils exert a unique mechanism of cytotoxicity towards antibody-opsonized tumor cells, known as trogoptosis, which involves Fc-receptor (FcR)-mediated trogocytosis of cancer cell plasma membrane leading to a lytic/necrotic type of cell death. However, neutrophils prominently express the myeloid inhibitory receptor SIRPα, which upon interaction with the ‘don’t eat me’ signal CD47 on cancer cells, limits cytotoxicity, forming a mechanism of resistance towards anti-cancer antibody therapeutics. In fact, tumor cells often overexpress CD47, thereby even more strongly restricting neutrophil-mediated tumor killing. Blocking the CD47-SIRPα interaction may therefore potentiate neutrophil-mediated antibody-dependent cellular cytotoxicity (ADCC) towards cancer cells, and various inhibitors of the CD47-SIRPα axis are now in clinical studies. Here, we review the role of neutrophils in antibody therapy in cancer and their regulation by the CD47-SIRPα innate immune checkpoint. Moreover, initial results of CD47-SIRPα blockade in clinical trials are discussed.

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Targeting the CD47-SIRPα Innate Immune Checkpoint to Potentiate Antibody Therapy in Cancer by Neutrophils

Chronic unresolving inflammation is emerging as a key underlying pathological feature of many if not most diseases ranging from autoimmune conditions to cardiometabolic and neurological disorders. Dysregulated immune and inflammasome activation is thought to be the central driver of unresolving inflammation, which in some ways provides a unified theory of disease pathology and progression. Inflammasomes are a group of large cytosolic protein complexes that, in response to infection- or stress-associated stimuli, oligomerize and assemble to generate a platform for driving inflammation. This occurs through proteolytic activation of caspase-1-mediated inflammatory responses, including cleavage and secretion of the proinflammatory cytokines interleukin (IL)-1β and IL-18, and initiation of pyroptosis, an inflammatory form of cell death. Several inflammasomes have been characterized. The most well-studied is the nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3) inflammasome, so named because the NLRP3 protein in the complex, which is primarily present in immune and inflammatory cells following activation by inflammatory stimuli, belongs to the family of nucleotide-binding and oligomerization domain (Nod) receptor proteins. Several NLRP3 inflammasome inhibitors are in development, all with multi-indication activity. This review discusses the current status, known mechanisms of action, and disease-modifying therapeutic potential of RRx-001, a direct NLRP3 inflammasome inhibitor under investigation in several late-stage anticancer clinical trials, including a phase 3 trial for the treatment of third-line and beyond small cell lung cancer (SCLC), an indication with no treatment, in which RRx-001 is combined with reintroduced chemotherapy from the first line, carboplatin/cisplatin and etoposide (ClinicalTrials.gov Identifier: NCT03699956). Studies from multiple independent groups have now confirmed that RRx-001 is safe and well tolerated in humans. Additionally, emerging evidence in preclinical animal models suggests that RRx-001 could be effective in a wide range of diseases where immune and inflammasome activation drives disease pathology. 

https://link.springer.com/content/pdf/10.1007/s40265-023-01838-z.pdf

A Review of RRx-001: A Late-Stage Multi-Indication Inhibitor of NLRP3 Activation and Chronic Inflammation

No Food and Drug Administration-approved intervention exists for oral mucositis (OM) from chemoradiotherapy (CRT) used to treat head and neck cancers. RRx-001 is a hypoxia-activated, cysteine-directed molecule that affects key pathways involved in OM pathogenesis. This phase 2a, multi-institutional trial was designed to assess the safety and feasibility of 3 schedules of a fixed concentration of RRx-001; a standard-of-care arm was included to identify potential signals of efficacy for further study.This study enrolled patients with oral cavity and oropharynx squamous cell carcinoma receiving definitive or postoperative cisplatin-based CRT. Patients were randomized into 4 cohorts. In arms 1 to 3, RRx-001 was coinfused with patients' blood at differing intervals. Arm 4 was a control cohort of patients treated with CRT alone. Trained evaluators assessed OM using a standardized data collection instrument twice weekly during treatment and then until resolution. OM severity was scored centrally using World Health Organization criteria. Safety outcomes were assessed using National Cancer Institute - Common Terminology Criteriav4 benchmarks. Long-term tumor response was defined by Response evaluation criteria in solid tumors v1.1 criteria.Fifty-three patients were enrolled, with 46 and 45 individuals contributing safety and efficacy data, respectively. There were no severe adverse events attributed to the study drug. Across all 3 active arms, the study drug was infused fully per protocol in 86% of patients. All 3 RRx-001 treatment cohorts appeared to demonstrate a similar or lower OM duration relative to control; arm 1 had the lowest median duration of severe oral mucositis (SOM), 8.5 days versus 24 days in controls among patients who developed at least 1 day of SOM. There were no locoregional failures in any patient.Our results support the safety and feasibility of RRx-001 as an intervention to mitigate SOM. Additional studies are planned to confirm its efficacy. 

http://www.redjournal.org/article/S0360301622036835/pdf

PREVLAR: Phase 2a randomized trial to assess the safety and efficacy of RRx-001 in the attenuation of oral mucositis in patients receiving head and neck chemoradiotherapy.

After extensive screening of aerospace compounds in an effort to source a novel anticancer agent, RRx-001, a first-in-class dinitroazetidine small molecule, was selected for advancement into preclinical and clinical development. RRx-001 is a minimally toxic small molecule with a distinct chemical structure and mechanism of action. The paradox of RRx-001 is that it mediates both antitumor cytotoxicity and normal tissue protection. The question of exactly how RRx-001 does this, and by means of what mechanism(s), depending on the route of delivery, intravenous or intratumoral, are explored. RRx-001 is currently in phase 2 and 3 clinical trials for the treatment of multiple solid tumor malignancies and as a supportive care drug.

Discovery of RRx-001, a Myc and CD47 Downregulating Small Molecule with Tumor Targeted Cytotoxicity and Healthy Tissue Cytoprotective Properties in Clinical Development.

For close to 40 years small-cell lung cancer (SCLC) was adrift, as listless, and as idle as a painted ship on a painted ocean, with nary a breeze to blow in the direction of clinical progress or change. The preferred decades-old first line regimen was etoposide-platinum, to which ≥50% of patients respond, followed by decades-old, tired topotecan in second line for platinum sensitive patients, full stop, because there were no approved therapeutic options (nor generally any compelling experimental ones) in third line or beyond. In 2012 SCLC was designated by the U.S. Congress as a “recalcitrant” tumor type and for good reason: because most patients relapse, after the generally favorable response in first line, respond poorly, if at all to subsequent therapies, and rarely survive beyond 1 year. A significant sea change occurred in 2018 with the approval of nivolumab followed by pembrolizumab and atezolizumab in 2019, durvalumab in 2020, accelerated approval for lurbinectedin in 2020 and trilaciclib in 2021 for myelosuppression. In 2021, the US indications for nivolumab and pembrolizumab were withdrawn. Suddenly, a tumor type, whose name was virtually synonymous with stalled progress and movement, and which was much less well studied and funded than its more prevalent cousin, non-small cell lung cancer (NSCLC), finds itself in the eye of the storm, that is, at the epicenter of an intense flurry and ferment of activity, not all of it positive. This review surveys approved drugs and select up-and-coming ones in development for extensive stage SCLC.

A 2022 Update on Extensive Stage Small-Cell Lung Cancer (SCLC)

Gastric cancer is the second most prevalent cancer and the second leading cause of cancer-related death in China. The prognosis of metastatic gastric cancer is poor with a median overall survival of 8–10 months. Apatinib, an oral small-molecule, selective vascular endothelial growth factor receptor-2 tyrosine kinase inhibitor, is approved as third-line or subsequent therapy for gastric cancer in China. Several recent small-scale studies and case reports showed that it may be great help in improvement of prognosis as second-line treatment in patients with advanced or metastatic gastric cancer. Here, we present a case of advanced gastric adenocarcinoma with multiple hepatic metastases who was treated with apatinib plus paclitaxel as second-line therapy, realized a long progression-free survival of 37 months. Until 29 January 2022, the disease remains an efficacy of partial response. We believe that the good outcome of this case is not an accident, because of the typically hyper-vascular of his liver metastases, the treatment toxicities of hypertension and proteinuria, all may be potential predictive biomarkers for anti-angiogenic treatments.

Case report: Long-term partial response of apatinib plus paclitaxel as second-line therapy in a patient with metastatic gastric cancer

RRx-001, a CD47 antagonist via its inhibition of MYC and the γ-subtype of the peroxisome proliferator-activated receptor (PPAR) has been associated to date with minimal toxicity. The aim of this post-hoc analysis was to evaluate the toxicity and efficacy of RRx-001 in Asian patients since RRx-001, in the context of multiple Phase 3 studies, will be administered in China and Chinese territories as well as potentially throughout the rest of Asia. Patients received 4 mg of RRx-001 in three different antitumor clinical trials with chemotherapy and/or radiation and a retrospective subset efficacy and toxicity analysis was conducted for patients with Asian ancestry in comparison to patients with other ethnic backgrounds. The toxicity and efficacy data from these studies were similar between Asians and the rest of the treated patients. While the sample sizes are too small to draw definitive conclusions, at a dose of 4 mg, when RRx-001 is combined with chemotherapy, no apparent differences in terms of safety and efficacy are observed in cancer patients with Asian ancestry.

Xiaohui Wang

Papers

Discovery of RRx-001, a Myc and CD47 Downregulating Small Molecule with Tumor Targeted Cytotoxicity and Healthy Tissue Cytoprotective Properties in Clinical Development.

A 2022 Update on Extensive Stage Small-Cell Lung Cancer (SCLC)

Case report: Long-term partial response of apatinib plus paclitaxel as second-line therapy in a patient with metastatic gastric cancer

Subset analysis of safety and efficacy in asian patients treated with RRx-001 across three clinical trials.