Chordoma is the second most common primary malignant tumor of the spine. These tumors rarely metastasize but are considered malignant and, when present in younger individuals, can be aggressive. In the setting of unresectable primary, recurrent, or metastatic tumors the current armamentarium of adjuvant therapy for this condition is very limited. Recent research, however, has identified potential targets for immunotherapy, including the tumor associate antigens High Molecular Weight Melanoma Associated Antigen (HMW-MAA) and B7H3. The goal of this investigation was to correlate expression of B7H3 and HMW-MAA in chordoma tumors with disease severity and clinical outcome. Tissue MicroArrays (TMA) were constructed using an automated arrayer to include 70 conventional chordoma tumors obtained from archives at our institution. Triplicate cores (0.6 mm in diameter) from each sample were created and two sets of cores were created for each chordoma specimen. One triplicate sample was incubated in a closed humid chamber with a pool of HMW-MAA-specific mAb, while the other was incubated with mAb specific for B7H3. Samples were washed in PBS and incubated with a secondary antibody for one hour. Staining was evaluated independently by two researchers and scored using validated systems. A retrospective chart review was performed for each chordoma specimen to determine demographic data, disease course, disease status at final follow-up and mortality. Clinical outcomes were then correlated to the expression of HMW-MAA and B7H3 within the chordoma lesions. Kaplan-Meier curves and Cox proportional hazard regression analysis were utilized to facilitate comparisons. Chordoma tumors from 70 patients were included in this study. Average age at the time of presentation was 57.4 years (31–88 years). Average follow-up was 5.5 years (3.6 months-21 years). Forty-three patients developed recurrences and 10 had metastatic disease. Twenty-three patients (33%) had died of disease at the time of final follow-up. Ninety-seven percent of chordoma tumors stained positive for B7H3 while 44% stained positive for HMW-MAA. No correlation could be drawn between clinical course, recurrence rate, or mortality and tumor expression of B7H3 and HMW-MAA. Kaplan-Meier analysis did demonstrate a shorter survival time for patients whose tumors stained positive for HMW-MAA compared to those whose tumors were negative for the antigen. The goal of this investigation was to correlate expression of B7H3 and HMW-MAA in chordoma tumorswith disease severity and clinical outcome. Results indicate that expression of HMW-MAA may be predictive of more aggressive disease and shorter survival. HMW-MAA and especially B7H3, in light of its near universal expression in the chordoma tumors studied here, may serve as potential targets for adjuvant immunotherapy.
