Could BMI predict mRCC treatment outcomes?

November 7, 2018

Body mass index appears to be a prognostic factor for treatment outcomes in patients with metastatic renal cell carcinoma, but the direction of the association might vary across treatment modalities.

Body mass index (BMI) appears to be a prognostic factor for treatment outcomes in patients with metastatic renal cell carcinoma (mRCC), but the direction of the association might vary across treatment modalities, according to research presented at the European Society for Medical Oncology annual congress in Munich, Germany.

In a retrospective study that included data for a total of 379 patients diagnosed with mRCC between 2009 and 2017, higher BMI was found to be associated with better overall survival in patients treated with vascular endothelial growth factor tyrosine kinase inhibitors (VEGF-TKIs) or mammalian target of rapamycin (mTOR) inhibitors. An opposite trend was observed, however, among patients who were treated with an immune checkpoint inhibitor as those with normal BMI had a longer overall survival than their counterparts who were overweight.

“Our finding for the patient group receiving VEGF-TKI is in alignment with previously reported information in the literature that suggests better survival in mRCC patients with high BMI. With immunotherapy, we found that overall survival was longer in patients with lower BMI, although the difference between BMI subgroups did not achieve statistical significance,” said Nazli Dizman, MD, of City of Hope Comprehensive Cancer Center, Duarte, CA.

Also see: Ablative RT could be alternative for solitary-kidney RCC

“Our study, however, included a small cohort of patients receiving immunotherapy, and we are planning to look at this issue again in the future in a larger sample. Reassessment in a larger prospective setting would help enhance our understanding of the associations between BMI and treatment outcomes for patients with mRCC as well as potential mechanisms,” added Dr. Dizman, working with Sumanta K. Pal, MD, and colleagues.

Patients included in the study were diagnosed with mRCC at a City of Hope location and had received treatment with a VEGF-TKI, mTOR inhibitor, or immunotherapy as first- or second-line treatment. Of the 379 patients included in the study, 230 were treated with a VEGF-TKI, 85 received an mTOR inhibitor, and 64 received immunotherapy.

An association between BMI and treatment outcome was analyzed by dividing patients into normal weight and overweight subgroups using a cutoff of 25 kg/m2. The majority of patients in the VEGF-TKI, mTOR inhibitor, and immunotherapy groups were in the overweight category(68%, 56%, and 72%, respectively).

Continue to the next page for more.Overall survival was analyzed using the Kaplan-Meier method. In the VEGF-TKI treatment group, median OS for the normal weight and overweight patients was 23.0 months vs. 36.0 months (p=.01). The results were similar for the mTOR inhibitor group where median OS was 18.0 months for normal weight patients and 24.0 months for overweight patients (p=.02). Among patients receiving immunotherapy, overall survival was 55.0 months in the normal weight subgroup and 22.9 months in the overweight patients (p=.19).

Dr. Dizman noted that more research is also needed to understand mechanism(s) underlying possible prognostic associations between BMI and mRCC treatment outcomes using different therapeutic modalities.

Read: Germline mutation prevalence high in RCC subset

“Comprehensive understanding of this association might point to new therapeutic targets,” he told Urology Times.

“We anticipate that a difference between targeted therapies and immunotherapies might be related to differences in their effects on an alternative pathway, perhaps involving fatty acid metabolism that is affected by targeted therapies but not by immunotherapies. But definitely there is more to learn about immunologic, genomic, and metabolic features of different BMI subgroups to answer the questions on pathophysiological basis of our clinical findings.” Dr. Dizman told Urology Times.