Abstract
2584 Background: The bispecific antibody catumaxomab (anti-EpCAM x anti-CD3) which is approved for the treatment of malignant ascites (MA) patients (pts) in the EU elicits a humoral immune response against tumor-associated antigens. Here we present follow up data analyzing the influence of this antibody response on puncture free (PFS) and overall survival (OS). Methods: In the course of the phase IIIb study CASIMAS, MA pts with EpCAM positive tumors were treated with/without prednisolone premedication by 4 infusions of 10, 20, 50 and 150 µg of catumaxomab over 11 days (d). EpCAM and HER2-specific antibody responses in plasma samples of 23 pts were measured by ELISA. Additionally, samples of 5 pts receiving a second treatment cycle were analyzed. Pts with significant increase (≥ 2) or de novo development of anti-tumor antibodies within 38 d after treatment start were defined as responders (R). Non responders (NR) showed no humoral response by d 38 or died before. PFS and OS of R and NR were compared by Kaplan Meier analysis. Results: 11 of 23 pts (48%) showed an anti-EpCAM response and 14 of 23 pts (61%) developed HER2-specific antibodies. 6 pts (26%) reacted positive against both antigens, 4 pts (17%) had neither response. In contrast to the EpCAM R group where 73% of pts displayed detectable antibodies prior to therapy, antibodies against HER2 developed de novo. Of note, 4 of 5 individuals who received a second treatment cycle after recurring MA demonstrated an anti-HER2 Ig booster reaction which was stronger and faster in comparison to pts who received only one treatment cycle (median values at d 18: 65 vs. 11 ng/ml). Most important, there was an almost 6 fold increase in median PFS between the HER2 R and NR group (68 vs 12 d, p = 0.044 (log-rank). There was also a trend towards improved OS for pts showing either anti-HER2 and/or anti-EpCAM responses (n=19) in comparison to pts with no response at all (n=4; 143 vs. 67 d, median, p = 0.054). Conclusions: The results indicate that active anti-tumor immunization triggered by catumaxomab treatment in MA pts is associated with improved clinical outcome. Further investigations of these vaccine-like effects with higher pts numbers are warranted.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
