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Abstract Introduction: The prognosis of patients (pts) with histological transformation (HT) of Waldenström macroglobulinemia (WM) remains dismal with standard chemoimmunotherapy. CD19-targeted chimeric antigen receptor T-cell therapies (CAR-T) can lead to durable responses in relapsed/refractory (R/R) large B-cell lymphoma (LBCL) and are approved in the second or third line settings. Pts with HT-WM were largely excluded from CAR-T trials. We previously reported high response rates in a series of 23 pts. The aim of the present study was to evaluate a larger cohort of pts with R/R HT-WM treated with CAR-T with a longer follow-up. Methods: We performed a multicenter retrospective study of pts with biopsy-proven transformed WM/lymphoplasmacytic lymphoma treated with CAR-T in the French DESCAR-T registry (NCT04328298), 4 centers from ECWM and 4 US centers. This study includes updated data from previously published cases (Durot et al, Blood, 2024). Responses were assessed according to the Lugano 2014 criteria. Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) were graded according to the ASTCT 2019 consensus criteria. Hematological toxicity and infections were graded according to the NCI CTCAE (version 5.0). Progression-free survival (PFS) and overall survival (OS) were calculated from the date of CAR-T infusion and estimated using the Kaplan-Meier method. Results: 50 pts were included (39 from DESCAR-T centers, 7 from US centers and 4 from ECWM centers). Median age was 60 (range: 32-72) and 68 (range: 42-82) years at WM diagnosis and CAR-T infusion, respectively. MYD88L265P and CXCR4 mutations were present in 79% (23/29) and 15% (2/13) of patients with available data, respectively. The median time from WM to HT diagnosis was 5.3 years (range: 0-32). Median prior lines of therapy was 1 (range: 0-9) for WM and 2 for HT (range: 0-4). Twenty (40%) pts previously received a BTK inhibitor for WM or HT, 12 (24%) underwent prior autologous SCT and 1 pt allogeneic SCT. 40% of pts presented primary refractory disease and 44% were refractory to last treatment before CAR-T. 40 pts (80%) received bridging therapy, of whom 17 (44%) responded (7 complete responses (CR)). 35 (70%), 10 (20%), and 5 (10%) pts received axicabtagene ciloleucel (axi-cel), tisagenlecleucel (tisa-cel), and lisocabtagene maraleucel (liso-cel), respectively. The best overall response rate (ORR) was 94%, with 44 (88%) pts reaching CR. With a median follow-up of 25.7 months (range: 1-69) from CAR-T infusion, the median PFS was 1.2 years (95% CI: 0.5-4.5) and median OS was 4.2 years (95% CI: 1.2-not reached). Median duration of response was 1.5 years (95% CI: 0.4-4.4), with a median of 4 years (95% CI: 1.5-NR) for pts still in CR at 6 months after CAR-T. 22 pts experienced relapse/progression after CAR-T, 19 related to LBCL and 3 to WM. Median survival after relapse was 7.9 months (95% CI: 3.8-25.3). At LBCL relapse after CAR-T, salvage therapy consisted of CD20xCD3 bispecific antibodies for 9 pts, lenalidomide +/- anti-CD20 or anti-CD19 antibody for 6 pts, and BTKi for 3 pts. Among 19 pts who died, 14 (74%) were due to progressive disease and 5 (26%) from infections. 37 (76%) pts experienced CRS, including 2 (4%) grade 3 events, and 22 (45%) had ICANS, with 2 (4%) ≥ grade 3 events. 17 (35%) pts presented infections, including 12 ≥ grade 3. 21 (43%) pts developed ≥ grade 3 prolonged cytopenias (ie, not resolved within 30 days post infusion). CNS involvement due to LBCL was present in 11 pts (22%) at the time of CAR-T. 6 of them had ICANS, with 1 grade 4. The best ORR was 91% (best CR 91%). Only 1 patient did not obtain a response, with stable disease at 1 month and progression at 3 months. The median PFS was 1.2 year (95% CI: 0.2-NR) and median OS was NR (95% CI: 0.5-NR). On univariate analysis, only elevated LDH was correlated with worse PFS (HR 2.5, p=0.04) and OS (HR 3.3, p=0.04). Other variables, including number of prior lines of therapy, MYD88 mutation status, primary refractory disease, refractory to last treatment, CNS involvement before CAR-T, response after bridging therapy and type of CAR-T received, were not associated with inferior PFS or OS. Conclusion: This cohort represents the largest series of pts with transformed WM treated with anti-CD19 CAR-T. We confirm the high efficacy previously reported with an acceptable safety profile, including for pts with CNS involvement due to LBCL at CAR-T infusion.

AbstractIdiopathic multicentric Castleman disease (iMCD) is a rare immunologic disorder characterized by systemic inflammation, multicentric lymphadenopathy, and organ dysfunction. Enlarged lymph nodes demonstrate a spectrum of characteristic but variable histopathologic features historically categorized into hyaline vascular (HV) (or hypervascular [HyperV] more recently), plasmacytic, or “mixed.” Though the etiology is unknown, a pro‐inflammatory cytokine storm, often involving interleukin‐6 (IL‐6), contributes to pathogenesis. Anti‐IL‐6 therapy with siltuximab is the only FDA‐ or EMA‐approved treatment based on efficacy and safety in multiple studies. Importantly, no patients considered to have HV histopathology achieved the primary endpoint in the Phase II study. NCCN currently recommends siltuximab first‐line for iMCD, except for patients considered to have HV histopathology. We investigated whether histopathologic subtype should guide siltuximab treatment decisions. Secondary analyses of clinical trial and real‐world data revealed similar clinical benefit across histopathologic subtypes. Notably, only 18 of 79 patients in the Phase II study were consistently classified into histopathologic subtype by three independent review panels, demonstrating limited reliability to guide treatment decisions. Real‐world data further demonstrate siltuximab's effectiveness in patients considered to have HV (or HyperV). Though histopathology is a critical component for diagnosis, there is insufficient evidence to guide treatment based solely on lymph node histopathologic subtype.

Abstract Castleman disease (CD) describes a group of heterogeneous hematologic disorders with characteristic histopathological features. CD can present with unicentric or multicentric (MCD) regions of lymph node enlargement. Some cases of MCD are caused by human herpesvirus-8 (HHV-8), whereas others are HHV-8–negative/idiopathic (iMCD). Treatment of iMCD is challenging, and outcomes can be poor because no uniform treatment guidelines exist, few systematic studies have been conducted, and no agreed upon response criteria have been described. The purpose of this paper is to establish consensus, evidence-based treatment guidelines based on the severity of iMCD to improve outcomes. An international Working Group of 42 experts from 10 countries was convened by the Castleman Disease Collaborative Network to establish consensus guidelines for the management of iMCD based on published literature, review of treatment effectiveness for 344 cases, and expert opinion. The anti–interleukin-6 monoclonal antibody siltuximab (or tocilizumab, if siltuximab is not available) with or without corticosteroids is the preferred first-line therapy for iMCD. In the most severe cases, adjuvant combination chemotherapy is recommended. Additional agents are recommended, tailored by disease severity, as second- and third-line therapies for treatment failures. Response criteria were formulated to facilitate the evaluation of treatment failure or success. These guidelines should help treating physicians to stratify patients based on disease severity in order to select the best available therapeutic option. An international registry for patients with CD (ACCELERATE, #NCT02817997) was established in October 2016 to collect patient outcomes to increase the evidence base for selection of therapies in the future.

AbstractObjectiveTo test the theoretical utility of incorporating nonavalent vaccination against HPV into a clinical setting.MethodsThe present retrospective study included data from consecutive patients who underwent HPV‐DNA testing between January 1, 1998, and December 31, 2015. Changes in the prevalence of different HPV types were assessed during three periods (T1, 1998–2003; T2, 2004–2009; and T3, 2010–2015) using XY analysis.ResultsThe study included a total of 13 665 patients. Overall, 1361, 5130, and 7174 patients were included in the T1, T2, and T3 periods, respectively. The quadrivalent vaccine would have potentially protected against HPV in 71.5% (973/1361), 46.5% (2385/5130), and 26.5% (1901/7174) of patients in T1, T2, and T3, respectively (P<0.001 for trend). The nonavalent vaccine could have protected against HPV in 92.5% (1259/1361), 72.3% (3709/5130), and 58.1% (4168/7174) of patients in T1, T2, and T3, respectively (P<0.001 for trend). The proportion of patients with genital dysplasia grade 2+ who did not have infections with HPV genotypes covered by the quadrivalent or nonavalent vaccines increased across the three periods (P<0.001 for trend). For all study periods, the protection provided by the nonavalent vaccine would have been superior to the quadrivalent vaccine (χ2 test P<0.001).ConclusionThe introduction of a nonavalent vaccine could improve protection against HPV infections and HPV‐related genital dysplasia.