Purpose: To assess the performance and potential clinical impact of a totally human monoclonal antibody, 88BV59 (HumaSPECT) (INTRACEL, Corp, Rockville, MD), in 202 assessable presurgical patients with recurrent, metastatic, or occult colorectal cancer.
Methods: 88BV59, labeled with technetium Tc 99m (99mTc) (HumaSPECT-Tc), was injected intravenously, and planar and single photon emission tomography (SPECT) images were obtained 14 to 20 hours postinjection. Surgical and pathologic verification of tumor were used as the standard against which the performance of HumaSPECT-Tc imaging and computed tomography (CT) analysis were evaluated.
Results: All patients entered onto the recurrent disease study had at least one tumor site defined on CT. The sensitivity of HumaSPECT-Tc in those CT-positive patients was 87%. The specificity of HumaSPECT-Tc was 57% compared with 17% for CT and the difference was statistically significant (P < .001). The diagnostic information provided by HumaSPECT-Tc significantly (P < .001) improved the accuracy of the identification of resectable and nonresectable disease over that of CT (80% v 62%). HumaSPECT-Tc scans resulted in a significant (P < .001) reduction versus CT in terms of the proportion of patients understaged (27% v 41%) and overstaged (4% v 26%). In patients with occult disease (increasing carcinoembryonic antigen [CEA] titer, negative diagnostic work-up, negative CT), HumaSPECT-Tc correctly identified disease in 15 of 22 (68%) patients. HumaSPECT-Tc images provided additional clinical data that would have affected patient management decisions in 40 of 202 (19.8%) patients. In 365 patients who received 88BV59, only a single detectable human anti-human antibody (HAHA) response (90 ng/mL) at 9 weeks postinfusion was observed.
Conclusion: HumaSPECT-Tc can provide important and accurate information about the presence and location of disease in patients with a high clinical suspicion of metastatic or recurrent colorectal cancer and either positive (known disease) or negative (occult disease) CT scans.