Langerhans cell histiocytosis (LCH) can affect children and adults with a wide variety of clinical manifestations, including unifocal, single-system multifocal, single-system pulmonary (smoking-associated), or multisystem disease. The existing paradigms in the management of LCH in adults are mostly derived from the pediatric literature. Over the last decade, the discovery of clonality and MAPK-ERK pathway mutations in most cases led to the recognition of LCH as a hematopoietic neoplasm, opening the doors for treatment with targeted therapies. These advances have necessitated an update of the existing recommendations for the diagnosis and treatment of LCH in adults. This document presents consensus recommendations that resulted from the discussions at the annual Histiocyte Society meeting in 2019, encompassing clinical features, classification, diagnostic criteria, treatment algorithm, and response assessment for adults with LCH. The recommendations favor the use of 18F-Fluorodeoxyglucose positron emission tomography-based imaging for staging and response assessment in the majority of cases. Most adults with unifocal disease may be cured by local therapies, while the first-line treatment for single-system pulmonary LCH remains smoking cessation. Among patients not amenable or unresponsive to these treatments and/or have multifocal and multisystem disease, systemic treatments are recommended. Preferred systemic treatments in adults with LCH include cladribine or cytarabine, with the emerging role of targeted (BRAF and MEK inhibitor) therapies. Despite documented responses to treatments, many patients struggle with a high symptom burden from pain, fatigue, and mood disorders that should be acknowledged and managed appropriately.

Background: Azacitidine is the treatment backbone for patients with acute myeloid leukemia, myelodysplastic syndromes and chronic myelomonocytic leukemia who are considered unfit for intensive chemotherapy. Detailed reports on adverse events in a real-world setting are lacking. Aims: To analyze the frequency of adverse events in the Austrian Registry of Hypomethylating agents. To compare real-world data with that of published randomized clinical trials. Results: A total of 1406 patients uniformly treated with a total of 13,780 cycles of azacitidine were analyzed. Hematologic adverse events were the most common adverse events (grade 3–4 anemia 43.4%, grade 3–4 thrombopenia 36.8%, grade 3–4 neutropenia 36.1%). Grade 3–4 anemia was significantly more common in the Registry compared to published trials. Febrile neutropenia occurred in 33.4% of patients and was also more common in the Registry than in published reports. Other commonly reported adverse events included fatigue (33.4%), pain (29.2%), pyrexia (23.5%), and injection site reactions (23.2%). Treatment termination due to an adverse event was rare (5.1%). Conclusion: The safety profile of azacitidine in clinical trials is reproducible in a real-world setting. With the use of prophylactic and concomitant medications, adverse events can be mitigated and azacitidine can be safely administered to almost all patients with few treatment discontinuations.

(1) Background: mRNA COVID-19 vaccines are effective but show varied efficacy in immunocompromised patients, including allogeneic hematopoietic stem cell transplant (HSCT) recipients. (2) Methods: A retrospective study on 167 HSCT recipients assessed humoral response to two mRNA vaccine doses, using the manufacturer cut-off of ≥7.1 BAU/mL, and examined factors affecting non-response. (3) Results: Twenty-two percent of HSCT recipients failed humoral response. Non-responders received the first vaccine a median of 10.2 (2.5–88.9) months post-HSCT versus 35.3 (3.0–215.0) months for responders (p < 0.001). Higher CD19 (B cell) counts favored vaccination response (adjusted odds ratio (aOR) 3.3 per 100 B-cells/microliters, p < 0.001), while ongoing mycophenolate mofetil (MMF) immunosuppression hindered it (aOR 0.04, p < 0.001). By multivariable analysis, the time from transplant to first vaccine did not remain a significant risk factor. A total of 92% of non-responders received a third mRNA dose, achieving additional 77% seroconversion. Non-converters mostly received a fourth dose, with an additional 50% success. Overall, a cumulative seroconversion rate of 93% was achieved after up to four doses. (4) Conclusion: mRNA vaccines are promising for HSCT recipients as early as 3 months post-HSCT. A majority seroconverted after four doses. MMF usage and low B cell counts are risk factors for non-response.

Background: Despite major treatment advances, multiple myeloma remains incurable. The outcome of patients who are refractory to immunomodulatory agents, proteasome inhibitors, and anti-CD38 monoclonal antibodies is poor, and improved treatment strategies for this difficult-to-treat patient population are an unmet medical need. Methods: This retrospective, unicentric analysis included 38 patients with relapsed/refractory multiple myeloma or plasma cell leukemia who underwent allogeneic stem cell transplantation (allo-HSCT) between 2013 and 2022. Survival outcomes, relapse incidence, and non-relapse mortality were calculated according to remission status, date of allo-HSCT, cytogenetic risk status, timing, and number of previous autologous HSCTs. Results: The median PFS was 13.6 months (95% CI, 7.7–30.4) and the median OS was 51.4 months (95% CI, 23.5–NA) in the overall cohort. The cumulative incidence of relapse at 3 years was 57%, and non-relapse mortality was 16%. The median PFS and OS were significantly longer in patients with very good partial remission (VGPR) or better compared to patients with less than VGPR at the time of allo-HSCT (mPFS 29.7 months (95% CI, 13.7–NA) vs. 6.5 months (95% CI, 2.6–17.0); p = 0.009 and mOS not reached vs. 18.6 months (95% CI, 7.0–NA); p = 0.006). Conclusion: For selected patients, allo-HSCT may result in favorable overall survival, in part by providing an appropriate hemato-immunological basis for subsequent therapies.

Background: T-prolymphocytic leukemia (T-PLL) is a rare lymphoid neoplasm with particularly poor prognosis. Although it is no longer recognized as a distinct entity by the World Health Organization (WHO), B-prolymphocytic leukemia (B-PLL) comprises conditions with unfavorable outcomes. Both diseases most frequently affect patients in the seventh decade of their lives. Allogeneic hematopoietic stem cell transplantation (alloHSCT) significantly improves outcomes for selected PLL cases, as shown by several, mostly retrospective, analyses. Methods: In this article, we provide a review of existing PLL analyses, followed by a summary of cases treated at our center. We describe outcomes of six T-PLL and three B-PLL cases receiving alloHSCT at our institution between 2015 and 2022. Results: Despite a post-transplant 4-year cumulative relapse incidence of 61% in our T-PLL series, the median OS was 78 months, because relapse therapy was remarkably successful. All B-PLL patients are alive and relapse-free, with a median follow-up of 54 (range of 11–74) months. A poor pre-transplant Karnofsky performance status (KPS) (≤ 80%) and an HCT comorbidity index (HCT-CI) of ≥3 were significantly associated with post-transplant mortality. Conclusions: The comparatively favorable outcomes in our case series underline the increasing value of alloHSCT in PLL in the current era, as it offers a prospect of cure in selected patients with otherwise very poor prognosis.