Cancer is a global problem with no sign that incidences are reducing. The great costs associated with curing cancer, through developing novel treatments and applying patented therapies, is an increasing burden to developed and developing nations alike. These financial and societal problems will be alleviated by research efforts into prevention, or treatments that utilise off-patent or repurposed agents. Phytosterols are natural components of the diet found in an array of seeds, nuts and vegetables and have been added to several consumer food products for the management of cardio-vascular disease through their ability to lower LDL-cholesterol levels. In this review, we provide a connected view between the fields of structural biophysics and cellular and molecular biology to evaluate the growing evidence that phytosterols impair oncogenic pathways in a range of cancer types. The current state of understanding of how phytosterols alter the biophysical properties of plasma membrane is described, and the potential for phytosterols to be repurposed from cardio-vascular to oncology therapeutics. Through an overview of the types of biophysical and molecular biology experiments that have been performed to date, this review informs the reader of the molecular and biophysical mechanisms through which phytosterols could have anti-cancer properties via their interactions with the plasma cell membrane. We also outline emerging and under-explored areas such as computational modelling, improved biomimetic membranes and ex vivo tissue evaluation. Focus of future research in these areas should improve understanding, not just of phytosterols in cancer cell biology but also to give insights into the interaction between the plasma membrane and the genome. These fields are increasingly providing meaningful biological and clinical data but iterative experiments between molecular biology assays, biosynthetic membrane studies and computational membrane modelling improve and refine our understanding of the role of different sterol components of the plasma membrane.

Background: Patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) often have a poor prognosis despite therapies using second-line chemoimmunotherapy. Achievement of CR with second-line therapy is associated with improved long-term outcomes. Unfortunately, only 25-35% of patients achieve complete response (CR) with RICE chemotherapy alone. The addition of novel targeted agents such as Bruton Tyrosine Kinase inhibitors (BTKi) to second-line therapy may offer improved treatment responses given the importance of B-cell receptor (BCR) signaling in DLBCL. BTK has been shown to be essential for BCR-mediated activation of the NF- κB/Rel family of transcription factors and BCR signaling has been recognized as a key pathway in the pathogenesis of DLBCL. Moreover, NF-κB activity relies upon chronic active BCR signaling in activated B-cell-like DLBCL, which can be potentially blocked by kinase inhibitors targeting BTK. The goal of this study is to examine the feasibility and efficacy of adding the BTKi, acalabrutinib, to standard second-line therapy as a means to improve disease response. Establishing the feasibility of combining acalabrutinib with RICE chemotherapy in autologous hematopoietic cell transplantation (HCT) eligible and HCT ineligible patients with R/R DLBCL may provide the foundation for a larger study of efficacy and long-term outcomes of the combination therapy for patients with R/R DLBCL. Study Design and Methods: The primary objective of this phase 2 trial is to evaluate the tolerability, feasibility, and efficacy of combining acalabrutinib with RICE as second line therapy in R/R DLBCL patients. There are two study cohorts. Cohort A is open to R/R DLBCL patients who are eligible for autologous HCT. Cohort B is open to R/R DLBCL patients who are considered medically ineligible for autologous HCT. The primary endpoint for cohort A is to estimate the confirmed CR rate (RECIL 2017 criteria) prior to HCT in patients undergoing second-line therapy. The primary endpoint for cohort B is defined as the estimate of one-year progression-free survival in patients undergoing second-line induction and maintenance acalabrutinib therapy. Secondary endpoints include assessment of the proportion of patients completing 3 cycles of acalabrutinib with RICE and proceeding with HCT or 2 additional cycles of maintenance acalabrutinib for HCT ineligible patients, overall response rate, incidence of Grade 3/4 adverse events, and incidence of SAEs. Patients in cohort A receive 2 cycles of standard RICE salvage chemoimmunotherapy in combination with acalabrutinib, 100mg BID day 1-21 of a 21 day cycle. After 2 cycles of therapy, patients in cohort A undergo autologous stem cell mobilization and collection. Patients then receive a 3rd cycle of RICE in combination with acalabrutinib. PET-CT (PET3) is performed 14-21 days after day 1 of cycle 3 to assess response. Those patients with CR or partial response (PR) after PET3 proceed to autologous HCT with BEAM conditioning within 28-42 days of PET3. After adequate hematopoietic recovery, patients restart acalabrutinib 100mg BID as maintenance therapy for a period of 12 additional months. Patients in cohort B receive 3 cycles of RICE salvage chemoimmunotherapy in combination with acalabrutinib 100mg BID day 1-21 of a 21-day cycle followed by PET-CT (PET3) 14-21 days after start of Cycle 3. Patients without progressive disease at PET3 continue with acalabrutinib maintenance up to 12 additional cycles until disease progression or unacceptable toxicity. Patients demonstrating progressive disease are withdrawn from study treatment but their outcomes continue to be recorded and will be included in the final data analysis. Historical outcomes from completed, published prospective clinical trials using RICE chemoimmunotherapy serve as a reference for statistical calculations. This trial is currently ongoing and additional information can be found on clinicaltrials.gov NCT listing NCT03736616 Disclosures Bensinger: BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Amgen: Consultancy, Honoraria, Research Funding, Speakers Bureau; GSK: Consultancy, Honoraria, Research Funding, Speakers Bureau; Regeneron: Consultancy, Honoraria, Research Funding, Speakers Bureau. Mawad:Abbvie: Speakers Bureau; Adaptive Biotechnologies: Speakers Bureau. Glennie:Pharmacyclics: Speakers Bureau; Janssen: Speakers Bureau. Patel:Pharmacyclics: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Kite: Consultancy; AstraZeneca: Consultancy, Research Funding, Speakers Bureau; Adaptive Biotechnologies: Consultancy; Genentech: Consultancy, Speakers Bureau; Celgene/BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; BeiGene: Consultancy. OffLabel Disclosure: Acalabrutinib is used an investigational agent for DLBCL in this study.

For Triple Negative Breast Cancer (TNBC) patients, treatment commonly consists of surgery, local radiotherapy and systemic chemotherapy. Prognosis following metastatic relapse (which indicates failure of systemic chemotherapy) is poor as fewer than 1 in 10 of these patients survive longer than two-years. The 2017 WCRF Breast Cancer Continuous Update Project(1) reported convincing risk factors for BCa that are common comorbidities with hypercholesterolemia (e.g. obesity, waist-hip-ratio). At the nutrient-gene interaction level this is intriguing because cholesterol is hydroxylated into oxysterols (OHCs), a group of potent signaling molecules that drive TNBC metastasis through the Liver X Receptor (LXR) (2) and are elevated in serum at metastatic relapse (3) . Dietary (4) and pharmacological (5) interventions that lower circulating concentrations of cholesterol and oxysterols, also improve BCa disease free survival. Dietary phytosterols in particular not only reduce circulating cholesterol and OHC concentrations, but their structural similarity to OHCs suggests they are modulators of the LXR-OHC axis. The aims of this study were to evaluate i) if the LXR-OHC axis confers chemoresistance in BCa, and ii) if phytosterols antagonise this pathway.Pretreatment of TNBC cells in culture with LXR specific ligands led to altered intra-cellular retention of the fluorescent anthracycline, epirubicin (Fig 1) and altered epirubicin induced cell death in colony forming assays (Fig 2). To test if phytosterols could impair the oxysterol-LXR axis, stable LXR-reporter cell lines were generated. Transactivation of LXR was inhibited in the presence of Sitosterol or the synthetic LXR antagonist GSK2033 (Fig 3). Sitosterol treatment was also found to significantly impair TNBC mammosphere formation (Fig 4).Targeting LXR transcriptional capacity with highly specific ligands led to changes in retention of epirubicin and tumour cell survival. Phytosterol treatment impaired the ability of an endogenous OHC to transactivate LXR and for TNBC cells to form mammospheres. We have now begun measuring OHC and phytosterol content of primary tumours to evaluate if intra-tumoural concentrations of OHCs are sufficient to transactivate LXR and if they are functional biomarkers of tumour relapse. Giventhe ease with which phytosteorls could be adopted into therapeutic nutritional advice we propose they should be evaluated as modifiers of the chemoresponse in TNBC patients, particularly those who present with elevated circulating cholesterol. Fig. 2. Colony Forming Assay show LXR activity modifies cellular survival in response to epirubucin. Fig. 3. Transactivation of LXR by OHC is impaired by synthetic antagonist and Sitosterol (SIT). Fig. 4. Mammopshere formation is impaired by Sitosterol. All data show mean of 2-5 independent biological replicates. Student's t-test or ANOVA were used to assess statistical significance.