Cetuximab use without chronic antihistamine premedication

13521

Background: Cetuximab is a human-murine chimeric monoclonal antibody against EGFR with approximately a 3% reported incidence of severe (≥ grade 3) anaphylactoid reactions. The overwhelming majority of such reactions have been reported with the initial dose of cetuximab. Diphenhydramine (Benedryl)or a related antihistamine is often given as a premedication for cetuximab, however this may cause fatigue or other side effects. Most early clinical trials of cetuximab permitted investigator discretion in use of premedication beyond the initial cetuximab dose. Methods: We obtained an IRB waiver of authorization to review the records of patients treated with cetuximab at Memorial Sloan Kettering Cancer Center for the first year of commercial availability of cetuximb (Feb, 2004 through Feb, 2005). Computerized pharmacy records were reviewed to identify all patients who were treated with cetuximab (outside of a clinical trial) and use of premedication was then evaluated. Records of institutional adverse event reports regarding chemotherapy administration were reviewed, and, any moderate or severe/life-threatening reactions were evaluated for presence or absence of concurrent premedication. Results: As per our institutional guidelines, all patients received 50 mg of diphenhydramine prior to the initial loading dose of cetuximab, and 25 mg of diphenhydramine prior to the second dose. While there was inconsistency in terms of cessation of diphenhydramine, overall a total of 115 patients received one or more doses of cetuximab without premedication. A total of 746 doses of cetuxmab without diphenhydramine premedication were given over this time period. No severe/life-threatening reactions to cetuximab occurred during these doses given without premedication. Conclusions: Omission of diphenhydramine premedication after the initial two doses of cetuximab is our current institutional practice, and appears not to alter the safety profile of cetuximab. Considering the side effects of diphenhydramine, routine long tern use of antihistamine premedication with cetuximab administration does not appear to be warranted.

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Simplification of bevacizumab (bev) administration: Do we need 90, 60, or even 30 minute infusion times?

3542

Background: Bev is a humanized monoclonal antibody that targets VEGF. Due to concerns of infusion related hypersensitivity reactions, phase I trials of bev used an initial 90 minute infusion of bev, a 60 minutes for on the next dose, and 30 minutes for all doses thereafter. This has remained the administration schedule throughout development and registration. No significant infusion-related toxicities were reported in the pivotal phase III registration trial. We postulated therefore that bev could be safely given without initially prolonged infusion times. Methods: We obtained an IRB waiver of authorization to review the records of patients at Memorial Sloan Kettering Cancer Center (MSKCC) who were treated with bev in the first 3 months of commercial availability (cut-off date 5/15/05). Our institutional adverse drug reaction reporting program was utilized to identify any infusion reactions related to bev. Additionally, patient medical records were reviewed for further confirmation. Results: Following initial commercial availability of bev in February 2004, 202 consecutive colorectal cancer (CRC) patients were treated with bev (5 mg/kg) at MSKCC starting as a 90 minute, then 60 minute, then 30 minute infusion. No hypersensitivity reactions were seen. A decision was then made to establish an institutional practice of using 30 minute infusion times for all doses, including initial doses, of bev. Subsequently, 212 consecutive CRC patients were treated with bev 5 mg/kg, initially as a 30 minute infusion. No infusion reactions were observed. Conclusions: Administration of the initial dose of bev over 30 minutes appears to be safe and well-tolerated. This has been the standard initial infusion time at MSKCC for 5 mg/kg, 10 mg/kg and 15 mg/kg doses of bev. Based on our favorable experience with 30 minute infusions of 15 mg/kg (0.5 mg/kg/minute), as of Nov ’05 we have changed our institutional guidelines such that all non-protocol patients receiving bev are initiated at the infusion rate of 0.5 mg/kg/minute. Thus, our standard 5 mg/kg doses of bev are given over 10 minutes, 10 mg/kg doses are given over 20 minutes, and 15 mg/kg doses are given over 30 minutes. Active quality assurance and safety monitoring are maintained throughout. Data will be updated for the meeting.

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Characterization of the haemolytic activity of Streptococcus equi

The haemolytic activity of Streptococcus equi, the cause of equine strangles, was characterized. Production of haemolysin in Todd Hewitt broth was dependent on an equine serum supplement and the logarithmic phase of growth after which activity declined sharply. RNA core also induced haemolysin production from cells harvested at the end of the logarithmic phase of growth. Haemolysis was not affected by cholesterol, was only slightly increased in reducing conditions and was completely inactivated by trypan blue, identifying the haemolytic activity as streptolysin S-like (SLS-like). Purification by hydroxyapatite and Sephacryl column chromatography yielded proteins of molecular weights of approximately 6000 and 17 000-22 000 Da with a 64-fold increase in specific activity. Low molecular weight proteins from the RNA core were still present in the purified toxin. Two non-haemolytic mutants were derived by conjugation with an Enterococcus faecalis-carrying transposon Tn916. Southern blots of HindIII digests of DNA revealed that one of the mutants contained three transposon insertions and the other just one. A lambda phage library of S. equi contained plaques whose haemolytic activity was enhanced by reducing conditions and inhibited by cholesterol, suggesting a streptolysin O-like (SLO-like) activity. However, haemolysin in culture sonicates of host E. coli in which the lambda phage insert was subcloned into plasmid (pUC18), was not affected by these conditions. Seven isolates of S. equi in medium without SLS-like inducers showed no SLO-like activity and no evidence for an SLO-like toxin could be found by immunoblotting with pneumolysin antiserum and monoclonal antibodies or by polymerase chain reaction with primers derived from sequences conserved between the SLO genes of Lancefield group A, C and G streptococci. S. equi does not appear to possess a streptolysin O but does make a streptolysin S-like toxin whose production can be interrupted at just one genetic locus.

The effect of decomplementation on Erysipelothrix rhusiopathiae infection in the mouse

The intraperitoneal administration of heat-aggregated sheep γ-globulin to mice caused a greater than sixfold decline in serum complement. Decomplementation significantly decreased the mean time to death of mice infected intraperitoneally with Erysipelothrix rhusiopathiae, but final mortality in normal and decomplemented groups of mice was similar. When the challenge bacteria were pretreated with fresh mouse serum, decomplementation had no effect and mice survived a lethal challenge of serum-treated organisms. This protective property was removed by heating the mouse serum to 56° for 30 minutes. Decomplementation did not affect the progress of Erysipelothrix infection in mice with acquired antibody. This suggests that complement protects by opsonization.