Journal of Clinical Oncology, Vol 6, 203-212, Copyright © 1988 by American Society of Clinical Oncology
Protein A immunoadsorption in the treatment of malignant disease
GL Messerschmidt, DH Henry, HW Snyder Jr, J Bertram, A Mittelman, S Ainsworth, J Fiore, MV Viola, J Louie and E Ambinder
Protein A Clinical Trial Group, Wilford Hall USAF Medical Center, San Antonio, TX.
Circulating immune complexes (CIC) are known to be present in cancer
patients and are responsible for much of the cancer-associated
immunosuppression. Removal or modulation of these "blocking factors" can
reverse the immunosuppression. Protein A from Staphylococcus aureus has the
unusual property of binding to CIC with high avidity. Use of protein A as
an immunoadsorbent in extracorporeal immunotherapy affinity columns has
resulted in antitumor and antiviral responses in animals. Our group
developed a multicenter trial to assess toxicity and antitumor response
with this biologic response modifier alone. Overall, 24% (21 of 87
patients) had objective tumor regressions including both partial responses
(PR) and less than PR. No complete responses (CR) were observed. Responses
were observed in acquired immune deficiency syndrome (AIDS)-related
Kaposi's sarcoma (six of 17 PR; two of 17 less than PR; overall, 47%),
breast adenocarcinoma (five of 22 PR; three of 22 less than PR; overall
response, 36%), colon adenocarcinoma, (one PR, one less than PR; overall
response, 11%), and non-oat cell lung carcinoma (two of seven less than
PR). The procedure was well tolerated and could be performed on an
outpatient basis. No adverse reaction was observed in 735 of 1,113
treatments (66%). The most common adverse effect was an "influenza-like"
syndrome consisting of fever and chills. Pain was present in 12% of the
patients. There were no study-related deaths. Serum IgG and CIC levels did
not statistically change due to therapy in responding or nonresponding
patients. Complement levels remained within the normal range. Liver and
renal tests remained stable throughout the study. In summary, protein A
immunoadsorption of plasma is well tolerated in the outpatient clinic, has
demonstrated antitumor activity in resistant solid tumors, and functions as
a biologic response modifier.