Frequency of hepatitis B virus mutant in asymptomatic hepatitis B virus carriers receiving prophylactic lamivudine during chemotherapy for hematologic malignancies.

Hepatitis B virus (HBV) reactivation is a potentially fatal complication of chemotherapy in asymptomatic HBV carriers. Prophylactic lamivudine has proven effective for its prevention, but the potential emergence of lamivudine-resistant HBV YMMD mutants, as shown in patients treated for chronic hepatitis, may limit its use. To evaluate the frequency of HBV YMMD mutant and its clinical significance, we have analysed 32 courses of primary lamivudine prophylaxis given to HBV carriers with haematologic malignancies, from the start until 1-5 months after the end of chemotherapy. Lamivudine was used for a median of 6 months (range 2-24+) and median follow-up was 19.5 months (range 5-40). Four episodes of HBV reactivation with mild hepatitis and no evidence of mutant strain occurred after chemotherapy completion and after lamivudine withdrawal. At follow-up YMMD mutant was detected in one patient with normal transaminase levels, who had been on continuous lamivudine for 20 months. In conclusion, among HBV carriers treated with chemotherapy for haematologic malignancies, the emergence of HBV YMMD mutant occurred in 3.1% of prophylactic lamivudine courses and was of little clinical relevance.