Incident Kaposi sarcoma during the expansion of antiretroviral therapy eligibility in Nigeria: a retrospective cohort study

INTRODUCTION

The expansion of antiretroviral therapy (ART) eligibility could lead to earlier initiation of Human Immunodeficiency Virus (HIV) treatment and consequently reduce the risk of HIV-associated Kaposi Sarcoma (KS). We investigated the impact of changes in the Nigerian HIV treatment guidelines on KS incidence among adults enrolled in HIV care in Nigeria.

METHODS

We analyzed data of adults who enrolled for HIV care from January 2006 to December 2016 at one of Nigeria's largest HIV treatment centers. Based on changes in HIV treatment guidelines, we classified 2006-2009 as the pre-expansion period and 2010-2016 as the post-expansion period. We used Kaplan Meier curves to compare the incidence of KS in the pre-expansion to the post-expansion period. We used Cox regression models to assess the hazard for incident KS between the two periods after adjusting for potential confounders.

RESULTS

Among 14,479 patients with HIV, the overall KS incidence was 2.35; 95% CI 2.01-2.74/1,000 person-years. The incidence of KS decreased from 2.53 to 1.58 per 1,000 person-years from 2006 to 2009 to 2010-2016. In models adjusting for age, sex, CD4-T cell count, and ART use, the risk for KS remained lower in 2010-2016 compared to 2006-2009. In analyses restricted to time on ART, there was no significant difference in KS incidence between HIV patients who enrolled in 2006-2009 and 2010-2016 after adjusting for age, sex, and CD4 T-cell count.

CONCLUSION

The expansion of ART eligibility was associated with a reduced incidence of HIV-associated KS among adults initiating HIV care in Jos, Nigeria. The reduction was likely driven by earlier enrollment for HIV care and ART initiation.

Targeting the metabolic plasticity of multiple myeloma with FDA-approved ritonavir and metformin

PURPOSE

We have previously demonstrated that ritonavir targeting of glycolysis is growth inhibitory and cytotoxic in a subset of multiple myeloma cells. In this study, our objective was to investigate the metabolic basis of resistance to ritonavir and to determine the utility of cotreatment with the mitochondrial complex I inhibitor metformin to target compensatory metabolism.

EXPERIMENTAL DESIGN

We determined combination indices for ritonavir and metformin, impact on myeloma cell lines, patient samples, and myeloma xenograft growth. Additional evaluation in breast, melanoma, and ovarian cancer cell lines was also performed. Signaling connected to suppression of the prosurvival BCL-2 family member MCL-1 was evaluated in multiple myeloma cell lines and tumor lysates. Reliance on oxidative metabolism was determined by evaluation of oxygen consumption, and dependence on glutamine was assessed by estimation of viability upon metabolite withdrawal in the context of specific metabolic perturbations.

RESULTS

Ritonavir-treated multiple myeloma cells exhibited increased reliance on glutamine metabolism. Ritonavir sensitized multiple myeloma cells to metformin, effectively eliciting cytotoxicity both in vitro and in an in vivo xenograft model of multiple myeloma and in breast, ovarian, and melanoma cancer cell lines. Ritonavir and metformin effectively suppressed AKT and mTORC1 phosphorylation and prosurvival BCL-2 family member MCL-1 expression in multiple myeloma cell lines in vitro and in vivo.

CONCLUSIONS

FDA-approved ritonavir and metformin effectively target multiple myeloma cell metabolism to elicit cytotoxicity in multiple myeloma. Our studies warrant further investigation into repurposing ritonavir and metformin to target the metabolic plasticity of myeloma to more broadly target myeloma heterogeneity and prevent the reemergence of chemoresistant aggressive multiple myeloma.

Investigating and targeting chronic lymphocytic leukemia metabolism with the human immunodeficiency virus protease inhibitor ritonavir and metformin

Chronic lymphocytic leukemia (CLL) remains fatal due to the development of resistance to existing therapies. Targeting abnormal glucose metabolism sensitizes various cancer cells to chemotherapy and/or elicits toxicity. Examination of glucose dependency in CLL demonstrated variable sensitivity to glucose deprivation. Further evaluation of metabolic dependencies of CLL cells resistant to glucose deprivation revealed increased engagement of fatty acid oxidation upon glucose withdrawal. Investigation of glucose transporter expression in CLL reveals up-regulation of glucose transporter GLUT4. Treatment of CLL cells with human immunodeficiency (HIV) protease inhibitor ritonavir, which inhibits GLUT4, elicits toxicity similar to that elicited upon glucose deprivation. CLL cells resistant to ritonavir are sensitized by co-treatment with metformin, potentially targeting compensatory mitochondrial complex 1 activity. Ritonavir and metformin have been administered in humans for the treatment of diabetes in patients with HIV, demonstrating the tolerance to this combination in humans. Our studies strongly substantiate further investigation of Food and Drug Administration approved ritonavir and metformin for CLL.

Cancer metabolism as a therapeutic target

Cancer is now recognized to be a disease arising from both genetic and metabolic abnormalities. In the mid-1900s, Otto Warburg described the phenomenon of elevated glucose consumption and aerobic glycolysis, and the dependence of cancer cells on this phenomenon for proliferation and growth. The Warburg effect has formed the basis of such diagnostic and prognostic imaging modalities as positron emission tomography (PET); however, we have not yet capitalized on this phenomenon for therapy. Several mechanisms have now been shown to contribute to the Warburg effect.Ongoing studies are attempting to understand the reasons that tumor cells engage in aerobic glycolysis in lieu of oxidative phosphorylation, and the advantages that accrue to them as a result. In this review, we discuss known benefits to tumor cells from this metabolic switch, and we highlight key enzymes that play a role in aerobic glycolysis. We also describe novel therapeutic options targeting glucose metabolism and the importance of continuing to understand the metabolic plasticity of cancer.