The multi-kinase inhibitor Regorafenib, approved for the treatment of metastatic colorectal cancer, is poorly tolerated with a Grade 3/4 drug related adverse event rate of 54% resulting in frequent dose reductions and discontinuations. RRx-001 is a minimally toxic NLRP3 inhibitor small molecule with macrophage-repolarizing properties in Phase 3 clinical trials. Studies have demonstrated the inhibitory impact of M2 macrophages on the activity of tyrosine kinases, suggesting that the repolarization of macrophages by RRx-001 may enhance the activity of TKIs. The purpose of these experiments was to determine whether RRx-001 demonstrated in vitro and in vivo synergy with regorafenib in colorectal cancer and whether RRx-001 attenuated the toxicity of regorafenib. Tumor-bearing mice were randomized into four cohorts: RRx-001 alone, regorafenib alone, RRx-001 + regorafenib and control. RRx-001 demonstrated in vitro and in vivo synergy with regorafenib with attenuation of toxicity in colorectal cancer cell lines. These results provide a rationale to treat colorectal cancer with RRx-001 plus another tyrosine kinase inhibitor like regorafenib.

The goal of anticancer therapy is to selectively eradicate all malignant cells. Unfortunately for the majority of patients with metastatic disease, this goal is consistently thwarted by the nearly inevitable development of therapeutic resistance; the main driver of therapeutic resistance is a minority subpopulation of cancer cells called cancer stem cells (CSCs) whose mitotic quiescence essentially renders them non-eradicable. The Wnt signaling pathway has been widely implicated as a regulator of CSCs and, therefore, its inhibition is thought to result in a reversal of therapeutic resistance via loss of stem cell properties. RRx-001 is a minimally toxic redox-active epi-immunotherapeutic anticancer agent in Phase III clinical trials that sensitizes tumors to radiation and cytotoxic chemotherapies. In this article, as a potential mechanism for its radio- and chemosensitizing activity, we report that RRx-001 targets CD133 ⁺ /CD44 ⁺ cancer stem cells from three colon cancer cell-lines, HT-29, Caco-2, and HCT116, and inhibits Wnt pathway signalling with downregulation of c-Myc.

Few therapeutic options are available for T790M-negative non-small cell lung cancer (NSCLC) after failure of primary epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) and chemotherapy. This report presents the case of a 71-year-old Asian female never smoker with EGFR mutated T790M negative non squamous cell lung cancer (NSCLC) pre-treated with the experimental epi-immunotherapeutic agent, RRx-001, that re-responded to single agent carboplatin after failure of platinum doublets, TKIs, pemetrexed and nivolumab. The management of advanced EGFR mutation-positive NSCLC is briefly reviewed herein and the emerging paradigm of episensitization, which contradicts the long-standing and widely accepted tenet about the immutability of resistance and the futility of therapeutic rechallenge, is introduced as a strategy to avert treatment failure and thereby stave off deterioration and death.

Background

Bromonitrozidine (RRx-001) is a minimally toxic, NLRP3 inhibitor that has been observed, in experimental systems, to also downregulate CD47, repolarize tumor associated macrophages (TAMs) and normalize aberrant tumor perfusion. This phase 1 pilot study was undertaken to determine the safety and feasibility of RRx-001 and nivolumab in patients with advanced cancer and no standard options.

Methods

This single arm, single site, open-label pilot study (NCT02518958) called PRIMETIME was designed to evaluate the safety profile of RRx-001 and nivolumab in patients with advanced malignancies and no other standard therapeutic options. A 3 + 3 trial design was used to establish safety of the combination at each dose level and guide the decision to escalate dose. RRx-001 is infused once weekly while nivolumab is given at 3mg/kg once every 2 weeks. The RRx-001 starting dose was 2 mg IV weekly with 4 dose level escalations up to 16 mg IV weekly. From January 2015 to November 2015, twelve patients received treatment for only 4 cycles (total 12 weeks) with the combination due to unavailability of nivolumab, which was not supplied to the Sponsor. Treatment-emergent (all cause, TEAEs) and treatment-related (TRAEs) adverse events that occurred within 16 weeks of the first dose of RRx-001 and nivolumab were characterized according to CTCAE v4.03.

Results

Twelve patients received ≥1 dose of RRx-001 and nivolumab. One discontinuation occurred due to pneumonitis and one to voluntary withdrawal after a post-procedural infection. There were no DLTs. The main adverse event related to RRx-001 was infusion reaction (33.3%). The main adverse event related to the combination was pseudoprogression manifested by larger tumors in patients that were symptomatically improved (25%). The most common immune-related treatment-emergent AEs were pneumonitis (8.3%), and hypothyroidism (8.3%). The objective response rate at 12 weeks was 25% and the disease control rate (DCR) consisting of ≥SD was 67% by Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. 25% of the patients progressed on the combination.

Conclusions

The combination of RRx-001 and nivolumab was safe and well-tolerated with preliminary evidence of anti-cancer activity. Further clinical trials with RRx-001 and nivolumab are warranted.

Clinical trial registration

ClinicalTrials.gov identifier, NCT02518958.

RRx-001 is a shape shifting small molecule with Fast Track designation for the prevention/amelioration of chemoradiation-induced severe oral mucositis (SOM) in newly diagnosed Head and Neck cancer. It has been intentionally developed or engineered as a chimeric single molecular entity that targets multiple redox-based mechanisms. Like an antibody drug conjugate (ADC), RRx-001 contains, at one end a targeting moiety, which binds to the NLRP3 inflammasome and inhibits it as well as Kelch-like ECH-associated protein 1 (KEAP1), the negative regulator of Nrf2, and, at the other end, a conformationally constrained, dinitro containing 4 membered ring, which fragments under conditions of hypoxia and reduction to release therapeutically active metabolites i.e., the payload. This payload, which is delivered specifically to hypoperfused and inflamed areas, includes nitric oxide, nitric oxide related species and carbon-centered radicals. As observed with ADCs, RRx-001 contains a backbone amide linker attached to a binding site, which correlates with the Fab region of an antibody, and to the dinitroazetidine payload, which is microenvironmentally activated. However, unlike ADCs, whose large size impacts their pharmacokinetic properties, RRx-001 is a nonpolar small molecule that easily crosses cell membranes and the blood brain barrier (BBB) and distributes systemically. This short review is organized around the de novo design and in vivo pro-oxidant/pro-inflammatory and antioxidant/anti-inflammatory activity of RRx-001, which, in turn, depends on the reduced to oxidized glutathione ratio and the oxygenation status of tissues.

Small-cell lung cancer (SCLC), initially exquisitely sensitive to first-line cisplatin/etoposide, invariably relapses and acquires a multidrug chemoresistant phenotype that generally renders retreatment with first-line therapy both futile and counterproductive. This report presents the case of a 77-year-old Caucasian male with extensive-stage refractory SCLC who was restarted on platinum doublets as part of a clinical trial called TRIPLE THREAT (NCT02489903) involving pretreatment with the epi-immunotherapeutic agent RRx-001, and who achieved a partial response after only 4 cycles. The patient had received a platinum drug twice before, in 2009 for a diagnosis of non-small-cell lung cancer (squamous cell carcinoma) and in 2015 for SCLC, suggesting that RRx-001 pretreatment may sensitize or resensitize refractory SCLC patients to first-line chemotherapy.

Neuroendocrine tumors (NET) are a heterogeneous group of neoplasms defined by the presence of cells with secretory granules and the potential to produce and release high levels of vasoactive peptides into the circulation, leading to severe flushing and diarrhea, which may adversely affect quality of life. This report presents the case of a 64-year-old man with chronic refractory diarrhea due to pulmonary NET treated with the experimental anticancer agent RRx-001 in a phase II trial called TRIPLE THREAT with subsequent resolution of his diarrhea.

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.

In drug development a frequently used phrase is data-driven. Just as high-test gas fuels a car, so drug development runs on high-quality data; hence, good data management practices, which involve case report form design, data entry, data capture, data validation, medical coding, database closure, and database locking, are critically important. This review covers the essentials of clinical data management (CDM) for the United States. It is intended to demystify CDM, which means nothing more esoteric than the collection, organization, maintenance, and analysis of data for clinical trials. The review is written with those who are new to drug development in mind and assumes only a passing familiarity with the terms and concepts that are introduced. However, its relevance may also extend to experienced professionals that feel the need to brush up on the basics. For added color and context, the review includes real-world examples with RRx-001, a new molecular entity in phase III and with fast-track status in head and neck cancer, and AdAPT-001, an oncolytic adenovirus armed with a transforming growth factor-beta (TGF-β) trap in a phase I/II clinical trial with which the authors, as employees of the biopharmaceutical company, EpicentRx, are closely involved. An alphabetized glossary of key terms and acronyms used throughout this review is also included for easy reference.

RRx-001, an experimental systemically non-toxic epi-immunotherapeutic agent, which potentiates the resensitization of resistant cancer cells to formerly effective therapies, is under active investigation in several clinical trials that are based on sequential or concomitant rechallenge to resistant first- or second-line regimens. One of these trials is designated TRIPLE THREAT (NCT02489903), because it explores the conditioning or priming effect of RRx-001 on three tumor types - non-small cell lung cancer (NSCLC), small cell lung cancer and high-grade neuroendocrine tumors - prior to re-administration of platinum doublets. In follow-up to a recent case study, which describes early monotherapeutic benefit with RRx-001 in a refractory EGFR-mutated NSCLC tumor, we present subsequent evidence of a radiological partial response to reintroduced platinum doublets after RRx-001. For the 50% of patients with EGFR-mutated NSCLC who progress on EGFR-tyrosine kinase inhibitors (without evidence of a T790M mutations) as well as platinum doublets and pemetrexed/taxane, no other clinically established treatment options exist. A retrial of these therapies in EGFR-positive NSCLC patients via priming with epigenetic agents such as RRx-001 constitutes a strategy to 'episensitize' tumors (i.e. reverse resistance by epigenetic means) and to extend overall survival.