A double-blind randomized-phase II trial comparing immunization with antiidiotype goat antibody vaccine SCV 106 versus unspecific goat antibodies in patients with metastatic colorectal cancer

This article reports on the first double-blind randomized clinical study wi th an antiidiotype antibody vaccine in patients with metastatic colorectal carcinoma. The study was performed to determine immunological parameters, e fficacy, and tolerability of the vaccine. Forty-two patients with metastati c colorectal cancer were randomly assigned to multiple immunizations with g oat IgG antiidiotype vaccine SCV 106 (n = 21) or unspecific goat IgG as con trols (n = 21). The antiidiotype vaccine mimicked the 17-1A glycoprotein an tigen associated with colorectal cancer. Of the 42 patients entered, 39 wer e evaluable for efficacy (SCV 106, n = 18; controls, n = 21). Twenty-nine p atients raised antibodies to the vaccines (immunological responders, SCV 10 6, n = 12; controls, n = 17). Only in the SCV 106 group was a significant i ncrease (p = 0.002) of titers with specificity of antitumor antibody 17-1A found. According to the International Union Against Cancer (UICC) criteria no tumor response was observed. However, in the SCV 106 group the relative increase of carcinoembryonic antigen (CEA) levels between entry and observe d disease progression was lower (p = 0.03) and disease progression was dete rmined less frequently by development of new metastases (p = 0.001). On an intention-to-treat basis, the sur vival time difference between the two gro ups was not significant. Comparison of immunological responders in both gro ups revealed a significant survival advantage of the SCV 106-treated patien ts compared with controls (mean 67 versus 39 weeks; p = 0.01). Immunization s were well tolerated. Vaccination of immunologically responding metastatic colorectal carcinoma patients with SCV 106 leads to slowed disease progres sion and tumor dissemination and significantly prolongs survival time.