E3216. Patterns and Progression: Association Between Lipiodol (Guerbet) Deposition and Treatment Response in Metastatic Ocular Melanoma
  1. Aditi Patel; University of Iowa Hospitals and Clinics
  2. Mason Vaillancourt; University of Iowa Hospitals and Clinics
  3. Kayla Hietpas; OrthoCarolina Research Institute
  4. Chad Davis; University of Iowa Hospitals and Clinics; University of Missouri - Kansas City
Patients with hepatocellular carcinoma (HCC) who have conventional chemoembolization show a correlation between posttreatment Lipiodol (Guerbet) deposition and tumor treatment response. Immunoembolization for metastatic ocular melanoma is a similar procedure involving the intraarterial delivery of Lipiodol (Guerbet) plus immune stimulant (GM-CSF). It has yet to be studied if there is a correlation between Lipiodol (Guerbet) deposition and tumor response for these patients. The purpose of this study is to evaluate Lipiodol (Guerbet) deposition and tumor treatment response in patients with metastatic ocular melanoma.

Materials and Methods:
A retrospective review of eight patients (44 procedures) who underwent hepatic immunoembolization with Lipiodol (Guerbet) + GM-CSF for metastatic ocular melanoma was performed to evaluate overall tumor response utilizing M-RECIST criteria. Initial presentation, systemic chemotherapy, and tumor genetic profiles all were evaluated. The patients who underwent immunoembolization received one lobar treatment, and then 4 weeks later underwent contralateral lobar treatment. This continued until there was disease progression or multidisciplinary change in treatment plan such as enrollment in a clinical trial. For each patient, the three largest lesions were assessed at baseline and after each round (two separate lobar treatments) of treatment. The lesions were measured on CT or MRI per M-RECIST and Lipiodol (Guerbet) deposition was categorized as homogeneous, heterogenous, minimal, or peripheral. Images were reviewed by two evaluators independently and measurements were taken to check for changes in size compared to their baseline presentation and most recent prior imaging. Better response to treatment was only considered if the lesion showed stable size or size regression per M-RECIST criteria. Data was sorted into categories to evaluate for overall changes by a biostatistician.

There were 44 treatments (eight patients), where a treatment consisted of the left and right lobes of the liver, in the study that were measured. Of these, 25 treated lesions demonstrated peripheral Lipiodol (Guerbet) deposition, five had homogeneous deposition, nine demonstrated heterogenous deposition, and one demonstrated minimal deposition. The 25 lesions that demonstrated peripheral Lipiodol (Guerbet) deposition had variable responses to treatment; the majority did not decrease in size. The nine lesions with heterogeneous deposition did not have any regression/stable disease according to M-RECIST criteria. The lesions which demonstrated homogeneous deposition (5) showed three treatments that were stable or regressed in size.

Patients with HCC who undergo chemoembolization and have homogeneous deposition of Lipiodol (Guerbet) show better response to treatment. In the very limited patient population evaluated within this retrospective study, data suggest that homogeneous Lipiodol (Guerbet) deposition may also correlate with better treatment response in metastatic ocular melanoma.