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BACKGROUND:Multicentric Castleman disease (MCD) is a rare, systemic lymphoproliferative disorder driven by interleukin (IL)-6 overproduction. Siltuximab, an anti-IL-6 monoclonal antibody, has demonstrated durable tumor and symptomatic responses in a multinational, randomized, placebo-controlled study of MCD. METHODS:This preplanned safety analysis was conducted to evaluate the long-term safety of siltuximab treatment among 19 patients with MCD who had stable disease or better and were enrolled in a phase-1 study and subsequent ongoing, open-label, phase-2 extension study. Dosing was 11 mg/kg administered intravenously every 3 weeks, per protocol, or every 6 weeks at the investigator's discretion. Safety monitoring focused on potential risks associated with the anti-IL-6 mechanism of action. Investigator-assessed disease control status was also documented. RESULTS:Median treatment duration for the 19 patients was 5.1 (range 3.4, 7.2) years, with 14 (74%) patients treated for >4 years. Grade-≥ 3 adverse events (AEs) reported in >1 patient included hypertension (n = 3) and nausea, cellulitis, and fatigue (n = 2 each). Grade-≥ 3 AEs at least possibly attributed to siltuximab were leukopenia, lymphopenia, and a serious AE of polycythemia (n = 1 each). Hypertriglyceridemia and hypercholesterolemia (total cholesterol) were reported in 8 and 9 patients, respectively. No disease relapses were observed, and 8 of 19 patients were able to switch to an every-6-week dosing schedule. CONCLUSIONS:All MCD patients in this extension study have received siltuximab for a prolonged duration (up to 7 years) without evidence of cumulative toxicity or treatment discontinuations and with few serious infections. All patients are alive, demonstrate sustained disease control, and continue to receive siltuximab.

Introduction: Two phase 3 studies demonstrated superior efficacy of intravenous daratumumab (DARA IV) plus bortezomib/melphalan/prednisone (ALCYONE) or lenalidomide/dexamethasone (Rd; MAIA) versus standard-of-care regimens for transplant-ineligible newly diagnosed multiple myeloma. In these studies, patients could switch from DARA IV to subcutaneous daratumumab (DARA SC) while receiving daratumumab monotherapy in ALCYONE (as of Cycle 11) or daratumumab plus Rd in MAIA. The phase 3 COLUMBA study demonstrated noninferiority of DARA SC to DARA IV. DARA SC reduced administration time, allowing patients to spend less time in healthcare settings, a relevant practical consideration for patient care in the COVID-19 pandemic/settings of limited healthcare resources. Methods: DARA SC 1800 mg was administered every 4 weeks, per approved dosing schedules. We evaluated safety and patient-reported experience (ALCYONE only) among patients who switched from DARA IV to DARA SC. Results: Fifty-seven patients in ALCYONE and 135 in MAIA switched to DARA SC. Three (2.2%; MAIA) patients reported injection-site reactions, all of which were mild. No infusion-related reactions occurred with DARA SC. In ALCYONE, >80% of patients preferred DARA SC over DARA IV. Grade 3/4 treatment-emergent adverse events (TEAEs) occurred in 5.3% of patients in ALCYONE and 25.9% in MAIA; one (0.7%; MAIA) patient experienced a TEAE with an outcome of death. Conclusion: For transplant-ineligible newly diagnosed multiple myeloma, DARA SC (monotherapy/with Rd) was safe and preferred over DARA IV. ClinicalTrials.gov, NCT02195479/NCT02252172. [ABSTRACT FROM AUTHOR]