Chlamydia psittaci (Cp)-eradicating therapy with doxycycline is an active treatment against ocular adnexa MALT lymphoma (OAML): Final results of a multicentre prospective trial

Abstract

7559 Background: An association between OAML and Cp infection has been reported. Preliminary data suggest that patients (pts) with Cp-related OAML could achieve lymphoma regression after eradicating therapy with doxycycline, while data on the activity of this strategy in Cp-negative OAML are not available. Methods: In this multicentre prospective trial, 27 consecutive pts with OAML and measurable disease, at diagnosis (n = 15) or relapse, were treated with doxycycline 100 mg, bid orally, for 3 weeks. Objective response was the primary endpoint. The presence of Cp DNA in lymphoma samples was evaluated by TETR-PCR. Results: Tolerability was excellent in all pts but one. At a median follow-up of 13 mo. (range 3–45), response was complete (CR) in 6 pts and partial in 7 (ORR = 48%; 95% CI:30%-66%); three pts had a response <50%, 9 had stable disease (3–13 mo.), two had progressive disease. Response was slow; 5 pts achieved the best response only after one year of follow-up (median time to the best response: 6 mo.). TETR-PCR resulted positive in 11 (41%) pts and negative in 16. Lymphoma regression was observed in both PCR-positive and -negative pts (64% vs. 38%; p = 0.25), with a CR rate of 36% and 13% (p = 0.18), respectively. Response rate was similar between pts with conjunctival and intra-orbital lymphomas (43% vs. 54%, p = 0.71). The three pts with regional lymphadenopathies and three of the 5 pts with bilateral OAL achieved objective response (4 CRs), which lasted 3+, 13+, 16+, 22+, 26+, and 37 mo. In relapsed pts, objective response was observed in 3 of 5 previously irradiated pts and in 5 of 7 non-irradiated pts (p = 0.99). Twenty pts are failure-free, with a 2-yr FFS of 66±12%. Conclusions: Doxycycline is a fast, cheap and safe therapy, able to induce durable regression in 64% of Cp-related OAML. This antibiotic is a valid alternative against OAML, even in pts with multiple failures, involving previously irradiated areas or regional lymph nodes. We report for the first time responses also in PCR-negative OAML; this finding stimulates the development of more sensitive and specific methods for Cp detection and the study of potential associations with other infectious agents responsive to doxycycline. No significant financial relationships to disclose.