Although radiation is widely used to treat cancers, resistance mechanisms often develop and involve activation of DNA repair and inhibition of apoptosis. Therefore, compounds that sensitize cancer cells to radiation via alternative cell death pathways are valuable. We report here that ferroptosis, a form of nonapoptotic cell death driven by lipid peroxidation, is partly responsible for radiation-induced cancer cell death. Moreover, we found that small molecules activating ferroptosis through system xc – inhibition or GPX4 inhibition synergize with radiation to induce ferroptosis in several cancer types by enhancing cytoplasmic lipid peroxidation but not increasing DNA damage or caspase activation. Ferroptosis inducers synergized with cytoplasmic irradiation, but not nuclear irradiation. Finally, administration of ferroptosis inducers enhanced the antitumor effect of radiation in a murine xenograft model and in human patient-derived models of lung adenocarcinoma and glioma. These results suggest that ferroptosis inducers may be effective radiosensitizers that can expand the efficacy and range of indications for radiation therapy.

SummaryThe use of peritoneal dialysis (PD) has become wide spread since the introduction of continuous ambulatory PD more than 25 years ago. Over this time, many advances have been made and PD is an alternative to hemodialysis (HD), with excellent comparable survival, lower cost, and improved quality of life. The percentage of prevalent PD patients in the United States is approximately 7%, which is significantly lower compared with the 15% PD prevalence from the mid-1980s. Despite comparable survival of HD and PD and improved PD technique survival over the last few years, the percentage of patients performing PD in the United States has declined. The increased numbers of in-center HD units, physician comfort with the modality, perceived superiority of HD, and reimbursement incentives have all contributed to the underutilization of PD. In addition to a higher transplantation rate among patients treated with PD in the United States, an important reason for the low PD prevalence is the transfer to HD. There are various reasons for the transfer (e.g., episodes of peritonitis, membrane failure, patient fatigue, etc.). This review discusses the various factors that contribute to PD underutilization and the rationale and strategies to implement "PD first" and how to maintain it. The PD first concept implies that when feasible, PD should be offered as the first dialysis modality. This concept of PD first and HD second must not be seen as a competition between therapies, but rather that they are complementary, keeping in mind the long-term goals for the patient.

In the proper context, radiotherapy can promote antitumor immunity. It is unknown if elective nodal irradiation (ENI), a strategy that irradiates tumor-associated draining lymph nodes (DLN), affects adaptive immune responses and combinatorial efficacy of radiotherapy with immune checkpoint blockade (ICB). We developed a preclinical model to compare stereotactic radiotherapy (Tumor RT) with or without ENI to examine immunologic differences between radiotherapy techniques that spare or irradiate the DLN. Tumor RT was associated with upregulation of an intratumoral T-cell chemoattractant chemokine signature (CXCR3, CCR5-related) that resulted in robust infiltration of antigen-specific CD8 effector T cells as well as FoxP3 regulatory T cells (Tregs). The addition of ENI attenuated chemokine expression, restrained immune infiltration, and adversely affected survival when combined with ICB, especially with anti-CLTA4 therapy. The combination of stereotactic radiotherapy and ICB led to long-term survival in a subset of mice and was associated with favorable CD8 effector-to-Treg ratios and increased intratumoral density of antigen-specific CD8 T cells. Although radiotherapy technique (Tumor RT vs. ENI) affected initial tumor control and survival, the ability to reject tumor upon rechallenge was partially dependent upon the mechanism of action of ICB; as radiotherapy/anti-CTLA4 was superior to radiotherapy/anti-PD-1. Our results highlight that irradiation of the DLN restrains adaptive immune responses through altered chemokine expression and CD8 T-cell trafficking. These data have implications for combining radiotherapy and ICB, long-term survival, and induction of immunologic memory. Clinically, the immunomodulatory effect of the radiotherapy strategy should be considered when combining stereotactic radiotherapy with immunotherapy. .

Elevated serum uric acid levels are a frequent finding in persons with obesity, hypertension, cardiovascular and kidney disease as well as in those with the cardiorenal metabolic syndrome (CRS). The increased consumption of a fructose-rich Western diet has contributed to the increasing incidence of the CRS, obesity and diabetes especially in industrialized populations. There is also increasing evidence that supports a causal role of high dietary fructose driving elevations in uric acid in association with the CRS. Animal and epidemiological studies support the notion that elevated serum uric acid levels play an important role in promoting insulin resistance and hypertension and suggest potential pathophysiological mechanisms that contribute to the development of the CRS and associated cardiovascular disease and chronic kidney disease. To this point, elevated serum levels of uric acid appear to contribute to impaired nitric oxide production/endothelial dysfunction, increased vascular stiffness, inappropriate activation of the renin-angiotensin-aldosterone system, enhanced oxidative stress, and maladaptive immune and inflammatory responses. These abnormalities, in turn, promote vascular, cardiac and renal fibrosis as well as associated functional abnormalities. Small clinical trials have suggested that uric acid-lowering therapies may be beneficial in such patients; however, a consensus on the treatment of asymptomatic hyperuricemia is lacking. Larger randomized controlled trials need to be performed in order to critically evaluate the beneficial effect of lowering serum uric acid in patients with the CRS and those with diabetes and/or hypertension.