Radiographic myosteatosis is prognostic and predictive of ipilimumab outcomes in melanoma

Background

Fatty infiltration of muscle appears as low radiographic density (also called skeletal muscle density, SMD) on computed tomography (CT) imaging. Its presence is prognostic of outcomes across cancers. SMD in malignant melanoma (MM) has not been investigated in the immunotherapy era. This retrospective study examined the prognostic ability of SMD in ipilimumab-treated MM patients.

Methods

In this single center, retrospective study, advanced/metastatic MM patients (pts) treated with ipilimumab from 2009-2014 were reviewed. Pre-treatment CT images were used to determine body composition at the third lumbar vertebrae (L3) given its very accurate approximation of total body muscle and fat. SMD at L3 was measured and expressed in Hounsfield Units (HU). Cutpoint analysis determined whether a particular level of SMD demonstrated differences in progression free (PFS) and overall survival (OS). Secondary endpoints included objective response rates (ORR) and toxicities.

Results

Of 121 identified, 97 pts were evaluable. Baseline demographics included: 56 years median age, 58 male (60%), and 23 with BRAF mutations (23.7%). Cutpoint analysis found a prognostically significant difference between pts with SMD 

Conclusions

Low SMD is prognostic of melanoma outcomes in the immunotherapy era. SMD may relate to an underlying inflammatory state and therefore predict who may or may not respond to such therapy. It may also therefore point toward to immunotherapy resistance mechanisms.

Clinical trial identification

Not a clinical trial.

Legal entity responsible for the study

University of Alberta

Funding

N/A

Disclosure

All authors have declared no conflicts of interest.