Evaluation of toxic effects following administration of monoclonal antibody MBr1 in patients with breast cancer.

Twelve patients with disseminated breast cancer were injected with monoclonal antibody MBr1 at the National Cancer Institute of Milan, Italy, from January 1983 to March 1985. The first seven patients had advanced disease and the remaining five operable breast cancer. In the first seven patients the initial dosage of MBr1 was 0.5 mg and was doubled in the next patient up to 16 mg. The last five women received 10 mg of MBr1. No general side effects such as bronchospasm, hypotension, immediate or delayed allergic reactions were observed. Four patients who were injected with 10 mg or more experienced fever, shudder and vague abdominal and articular pain. The following tests were monitored: R.B.C., W.B.C., percentage of lymphocytes, blood glucose, urea nitrogen and creatinine, serum levels of Na+, K+, Cl-, total proteins levels, albumins and globulins, bilirubin, GOT, GPT, alkaline phosphatase, LDH, amylase, gamma GT and CPK. No major modifications were observed: a limited increase of the transaminases, LDH and gamma GT was evident at the last check. An early temporary alteration of CPK was observed in the four patients who had symptoms. Serum levels of MBr1 are detectable immediately after injection starting from 4 mg, and all sera were negative 48 hours later. It is concluded that the scanty toxicity allows to continue clinical investigations to verify the linkage between MBr1 and Ca-MBr1 "in vivo" after a single injection of no more than 16 mg of the MoAb. The increase of this dosage as well as multiple injections do not seem safe at present.