Uri Amit

BACKGROUND: Lymphopenia and high neutrophil-to-lymphocyte ratio are known negative prognostic factors in rectal cancer. Until recently, however, lymphopenia was regarded as a minor sequela following radiation therapy (RT). The immune system's influence on rectal cancer treatment outcomes led us to evaluate the impact of lymphopenia at various time points, before, during, and following radiotherapy. We hypothesized that chronic lymphopenia following radiotherapy might negatively influence the survival of patients, and pre-treatment lymphopenia may be predictive of poor outcomes. METHODS: This retrospective study involved 110 patients treated for rectal cancer between 2015 and 2019. The oncological outcomes are defined as alive without disease (AWOD), alive with disease (AWD), and death. These outcome probabilities tested against variables of lymphopenia before RT, during RT, and at several post-RT follow-up time points. RESULTS: At the end of the study, 69 patients were AWOD (63 %), 13 were AWD (12 %) and 28 had died (25 %). Treatment results were assessed with according level of lymphocytes measured one year following RT: 35 out of 39 patients (89.7 %) with normal values were AWOD. In 65 patients with sustained lymphopenia, 52 % were AWOD, 18.5 % AWD and 29 % died. A similar difference was found at all time-points up to 2 years following RT (p < 0.004). The results of our study shows that pre-existing lymphopenia (prior to RT) is associated with a 3 times greater chance of death compared to patients with normal lymphocyte levels prior to RT. The PFS significantly affected by lymphopenia at all time-points after RT. An NLR of more than 4 was associated with a 3-time higher risk of recurrence than lower NLR scores (p = 0.0054). CONCLUSION: Our results support the relevance of lymphopenia and NLR in the prognosis of rectal cancer. We believe this is the first study showing a negative correlation between sustained lymphopenia and OS following RT.

Abstract Aims Heart disease might be an independent risk factor for cancer (reverse cardio-oncology). The co-occurrence of these diseases worsens patients' prognoses and limits therapeutic options. However, the cellular and molecular mechanisms that link heart disease to cancer remain elusive. Therefore, we hypothesized that cardiac extracellular vesicles (cEVs) secreted by diseased hearts carry and disseminate factors that promote tumor growth. Methods and results We subjected female mice to myocardial infarction (MI) or sham-MI and 28 days of follow-up. Left ventricular remodeling and dysfunction were assessed by echocardiography. To determine the role of cEVs in tumor growth, we focused on cardiac mesenchymal stromal cells (cMSCs), which play a central role in cardiac repair, remodeling, and fibrosis. We isolated cMSCs from mice hearts 10 or 28 days after MI or sham MI and purified cMSC-EVs from the conditioned medium using size exclusion chromatography. cEVs were characterized by nanoparticle tracking analysis (NTA), the classical EV markers: CD81 and Tumor susceptibility gene 101, and electron microscopy. cMSCs after MI secreted more small EVs than cMSCs from sham-MI (Fig. 1A, p&amp;lt;0.0001). Proteomic and biological process analysis revealed a distinctive profile of cEVs after MI with more EV-encapsulated proteins related to inflammation, angiogenesis, and cell cycle (Fig. 1B). Purified cMSC-EVs were labeled with PKH26 dye and found to target both breast and lung cancer cells in vitro. Colorimetric proliferation assay showed that MI-cEVs facilitated cancer cells proliferation compared with sham-MI cEVs (n=7 in each group, p&amp;lt;0.0001). Furthermore, by scratch assay, MI-cEVs facilitated cancer cell migration two times faster than sham-MI cEVs (Fig. 1C, p=0.0002). Finally, we established 2 models of heart disease with cancer. Lung or breast cancer cells (750x103 or 250x103) were inoculated into the hind limb or mammary pad 10 days before or after MI. Serial ultrasound examinations monitored tumor growth. While MI significantly stimulated lung cancer growth, EV inhibition by GW4869 markedly attenuated the tumorigenic effect of MI and left ventricular (LV) dysfunction (Fig. 1D, p for GW4869 &amp;lt;0.0001). Moreover, we found an inverse correlation between LV ejection fraction (LVEF) and the volume of breast cancer tumors. cEV inhibition by GW4869 attenuated this inverse correlation (for vehicle group: n=14, r=−0.54 and p=0.04. for GW4869 group: n=13, r=−0.43, and p=0.14). Conclusions Our results suggest, for the first time, that cMSCs from the infarcted and failing heart secret EVs that target tumor cells and accelerate tumor growth. We propose cEVs as potential mediators and therapeutic targets in patients with concomitant heart disease and cancer. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Seymour Fefer Grant

Introduction: Chemokine (C-X3-C Motif) Receptor 1 (CX3CR1) is present in a subset of the immune cells in the tumor microenvironment (TME) and plays an essential and diverse role in cancer progression. However, its potential function in the irradiated TME remains unknown. Materials and Methods: A mouse lung cancer model was performed by subcutaneously inoculating Lewis Lung Carcinoma (LLC) cells expressing luciferase (Luc-2) and mCherry cells in CX3CR1GFP/GFP, CX3CR1DTR/+, and wild–type (WT) mice. Bioluminescence imaging, clonogenic assay, and flow cytometry were used to assess tumor progression, proliferation, and cell composition after radiation. Results: Radiation provoked a significant influx of CX3CR1-expressing immune cells, notably monocytes and macrophages, into the TME. Co-culturing irradiated LLC cells with CX3CR1-deficient monocytes, and macrophages resulted in reduced clonogenic survival and increased apoptosis of the cancer cells. Interestingly, deficiency of CX3CR1 in macrophages led to a redistribution of the irradiated LLC cells in the S-phase, parallel to increased expression of cyclin E1, required for cell cycle G1/S transition. In addition, the deficiency of CX3CR1 expression in macrophages altered the cytokine secretion with a decrease in interleukin 6, a crucial mediator of cancer cell survival and proliferation. Next, LLC cells were injected subcutaneously into CX3CR1DTR/+ mice, sensitive to diphtheria toxin (DT), and WT mice. After injection, tumors were irradiated with 8 Gy, and mice were treated with DT, leading to conditional ablation of CX3CR1-expressing cells. After three weeks, CX3CR1-depleted mice displayed reduced tumor progression. Furthermore, combining the S-phase-specific chemotherapeutic gemcitabine with CX3CR1 cell ablation resulted in additional attenuation of tumor progression. Conclusions: CX3CR1-expressing mononuclear cells invade the TME after radiation therapy in a mouse lung cancer model. CX3CR1 cell depletion attenuates tumor progression following radiation and sensitizes the tumor to S–phase-specific chemotherapy. Thus, we propose a novel strategy to improve radiation sensitivity by targeting the CX3CR1-expressing immune cells.

Abstract Introduction: Chemokine (C-X3-C Motif) Receptor 1 (CX3CR1) is present on a subset of the immune cells in the tumor microenvironment (TME) and plays an essential and diverse role in cancer progression. However, its potential function in the irradiated TME remains unknown. Materials and Methods: Mouse lung cancer model was performed by subcutaneously inoculating Lewis Lung Carcinoma (LLC) cells expressing luciferase (Luc-2) and mCherry cells in CX3CR1 GFP/GFP , CX3CR1 DTR/+ , and wild–type (WT) mice. Bioluminescence imaging, clonogenic assay, and flow cytometry were used to assess tumor progression, proliferation, and cell composition after radiation. Results: Radiation provoked a significant influx of CX3CR1-expressing immune cells, notably monocytes, into the TME. Co-culturing irradiated LLC cells with CX3CR1-deficient monocytes and macrophages resulted in reduced clonogenic survival and increased apoptosis of the cancer cells. Interestingly, depletion of CX3CR1 in macrophages led to a redistribution of the irradiated LLC cells in the S-phase, parallel to increased expression of cyclin E1, required for cell cycle G1/S transition. In addition, deletion of CX3CR1 expression in macrophages altered the cytokine secretion with a decrease of interleukin-6, a crucial mediator of cancer cell survival and proliferation. Next, LLC cells were injected subcutaneously into CX3CR1 DTR/+ mice, sensitive to diphtheria toxin (DT), and WT mice. After injection, tumors were irradiated with 8Gy, and mice were treated with DT, leading to conditional ablation of CX3CR1-expressing cells. After three weeks, CX3CR1 depleted mice displayed reduced tumor progression. Furthermore, combining the S-phase specific chemotherapy gemcitabine with CX3CR1 cell ablation resulted in additional attenuation of tumor progression. Conclusion: CX3CR1-expressing mononuclear cells invade the TME after radiation therapy in a mouse lung cancer model. CX3CR1 cell depletion attenuates tumor progression following radiation and sensitizes the tumor to S–phase-specific chemotherapy. Thus, we propose a novel strategy to improve radiation sensitivity by targeting the CX3CR1-expressing immune cells.