1787. The Safety and Efficacy of an Oral Penicillin Rechallenge Program in Cancer Patients: A Pilot Multicenter Study

BACKGROUND: Patient-reported antibiotic allergies (so-called antibiotic allergy labels [AALs]) are found in one in four cancer patients and significantly impact patient outcomes. Whilst 85% of AALs can be removed by skin testing, the role of simple point-of-care oral penicillin rechallenge in this cohort remains unknown. We report on a novel penicillin rechallenge program in cancer patients. METHODS: An oral penicillin rechallenge program was implemented at Austin Health (Melb, Aus) and Peter MacCallum Cancer Centre (Melb, Aus) on May 31, 2017. Patients were prospectively identified by Infectious Diseases and antimicrobial stewardship (AMS) services at both sites and reviewed by the conjoint Antibiotic Allergy Service for suitability as per the criteria outlined in Figure 1. Patients underwent supervised challenge with oral penicillin VK 250 mg or amoxicillin 250 mg, dependent on reported index allergy, and observed for 2-hours post. Patients were followed for up to 12 months post for adverse events and antibiotic usage. Figure 1. Selection algorithm for oral penicillin rechallenge program. RESULTS: Twenty-nine patients underwent penicillin oral challenge between May 31, 2017 to April 30, 2018, 15 with cancer. Of those with cancer, 8 (53%) were male, median age 56 years (IQR 44, 67), 15 (100%) avoiding penicillin, and 7 (47%) penicillins and cephalosporins. The penicillin–amoxicillin AAL phenotypes were “rash” in 73% (11/15) and “unknown” in 27% (4/15). Patients were challenged with penicillin VK or amoxicillin, based on their reported penicillin allergy with no positive challenges or adverse events noted in those with (n = 15) and without (n = 14) cancer. In the follow-up period, 88% (14/16) patients that were prescribed antibiotics received a narrow-spectrum β-lactam. CONCLUSION: A pilot penicillin oral rechallenge program was safe in cancer patients. This program serves as a future model for active “de-labelling” in carefully selected cancer patients, without formal allergy services, aiding AMS programs. DISCLOSURES: All authors: No reported disclosures.