Value of hemophagocytosis in the diagnosis of hemophagocytic lymphohistiocytosis in critically ill patients.

BACKGROUND: Ferritin is an established biomarker in the diagnosis of secondary hemophagocytic lymphohistiocytosis (HLH), which is diagnosed by the HLH-2004 criteria. Among these criteria, detection of hemophagocytosis through invasive procedures may delay early life saving treatment. Our aim was to investigate the value of hemophagocytosis in diagnosing HLH in critically ill patients. METHODS: In this secondary analysis of a retrospective observational study, we included all patients aged ≥18 years and admitted to any adult ICU at Charité-Universitätsmedizin Berlin between January 2006 and August 2018, who had hyperferritinemia (≥500 µg/L) and underwent bone marrow biopsy during their ICU course. RESULTS: Two hundred fifty-two patients were included, of whom 31 (12.3%) showed hemophagocytosis. In multivariable logistic regression analysis, maximum ferritin was independently associated with hemophagocytosis. By removing hemophagocytosis from HLH-2004 criteria and HScore, prediction accuracy for HLH diagnosis was only marginally decreased compared to the original scores. CONCLUSIONS: Our results strengthen the diagnostic value of ferritin and underline the importance of considering HLH diagnosis in patients with high ferritin but only four fulfilled HLH-2004 criteria, when hemophagocytosis was not assessed or not detectable. Proof of hemophagocytosis is not required for a reliable HLH diagnosis.

Final Results from RIBBIT: A Randomized Phase III Study to Evaluate Efficacy and Quality of Life in Patients with Metastatic Hormone Receptor-Positive, HER2-Negative Breast Cancer Receiving Ribociclib in Combination with Endocrine Therapy or Chemotherapy with or without Bevacizumab in the First-Line Setting.

Background: We investigated the efficacy and health-related quality of life (HRQoL) in patients receiving either ribociclib plus endocrine therapy (ET) or chemotherapy with/without bevacizumab as first-line treatment of metastatic hormone receptor (HR)-positive, HER2-negative breast cancer (BC). Patients and Methods: In this randomized, phase III study (RIBBIT), 38 patients diagnosed with metastatic HR-positive, HER2-negative BC with presence of visceral metastases recruited between May 2018 and December 2020 were randomly assigned in a 1:1 ratio to either arm A (ribociclib + ET) or arm B (chemotherapy with/without bevacizumab) at 12 sites in Germany. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall response rate (ORR), overall survival (OS), patient-reported HRQoL, and frequency and type of adverse events. During study conduction, the recruitment rate was persistently and considerably lower than originally expected. Therefore, the recruitment was ended prematurely. The study was initially designed to enroll and randomize 158 patients. Results: Median [95% CI] PFS was 27.3 months [19.1 - NA, parameter not estimable] in arm A and 15.8 months [8.2 - NA] in arm B. Complete responses were achieved only in arm A (n = 2, 10.5%). The ORR [95% CI] between arm A (57.9% [33.5-79.7]) and arm B (52.6% [28.9-75.6]) was comparable. Median OS [95% CI] was not reached in arm A, while in arm B median OS was 28.4 months [25.0 - NA]. Patients in arm A reported less burden by side-effects. No new safety signals emerged. Conclusion: Treatment of patients with visceral metastatic HR-positive, HER2-negative BC with ribociclib in combination with ET showed a tendency toward a more favorable clinical outcome. Despite small numbers of patients and sites, this head-to-head comparison with chemotherapy supports the use of ribociclib with ET in patients with visceral metastasis at risk of fast disease progression.

Lymphoma-associated hemophagocytic lymphohistiocytosis (LA-HLH): a scoping review unveils clinical and diagnostic patterns of a lymphoma subgroup with poor prognosis.

Hemophagocytic lymphohistiocytosis (HLH) is a severe hyperinflammatory syndrome driven by pathologic activation of cytotoxic T-lymphocytes and macrophages. Despite advances in diagnostics and management, adult patients with lymphoma-associated HLH (LA-HLH) harbor particularly poor prognosis and optimal treatment remains challenging. As systematic data on LA-HLH are scarce, we aimed to synthesize research evidence by thorough analysis of the published literature in PubMed (MEDLINE-database) within the context of a scoping review. Of 595 search results, 132 articles providing information on 542 patients were reviewed and analyzed. Median patient age was 60 years (range, 18-98) with male predominance (62.7%). B- and T-NHL were equally represented (45.6% and 45.2%), Hodgkin's lymphoma was reported in 8.9% of the cases. The majority of patients (91.6%) presented in Ann-Arbor-Stages III and IV, and bone marrow infiltration was observed in a significant proportion of patients (61.5%). Soluble CD25 levels were markedly elevated (median 10,000 U/ml), with levels beyond 10,000 U/ml indicating unfavorable prognosis for 30-day and overall survival. 66.8% of the patients died after median 5.1 months. LA-HLH remains a clinical challenge requiring specialized management. Timely diagnosis and appropriate lymphoma-specific treatment are of utmost importance to enhance patient outcomes.

A prospective observational study of real-world treatment and outcome in secondary CNS lymphoma.

BACKGROUND: Secondary central nervous system lymphoma (SCNSL) confers a dismal prognosis and treatment advances are constrained by the lack of prospective studies and real-world treatment evidence. METHODS: Patients with SCNSL of all entities were included at first diagnosis and patient characteristics, treatment data, and outcomes were prospectively collected in the Secondary CNS Lymphoma Registry (SCNSL-R) (NCT05114330). FINDINGS: 279 patients from 47 institutions were enrolled from 2011 to 2022 and 243 patients (median age: 66 years; range: 23-86) were available for analysis. Of those, 49 (20 %) patients presented with synchronous (cohort I) and 194 (80 %) with metachronous SCNSL (cohort II). The predominant histology was diffuse large B-cell lymphoma (DLBCL, 68 %). Median overall survival (OS) from diagnosis of CNS involvement was 17·2 months (95 % CI 12-27·5), with longer OS in cohort I (60·6 months, 95 % CI 45·5-not estimable (NE)) than cohort II (11·4 months, 95 % CI 7·8-17·7, log-rank test p < 0.0001). Predominant induction regimens included R-CHOP/high-dose MTX (cohort I) and high-dose MTX/cytarabine (cohort II). Rituximab was used in 166 (68 %) of B-cell lymphoma. Undergoing consolidating high-dose therapy and autologous hematopoietic stem cell transplantation (HDT-ASCT) in partial response (PR) or better was associated with longer OS (HR adjusted 0·47 (95 % CI 0·25-0·89), p = 0·0197). INTERPRETATION: This study is the largest prospective cohort of SCNSL patients providing a comprehensive overview of an international real-world treatment landscape and outcomes. Prognosis was better in patients with SCNSL involvement at initial diagnosis (cohort I) and consolidating HDT-ASCT was associated with favorable outcome in patients with PR or better.

Addendum to the German Consensus Recommendations on Ponatinib in the Treatment of Chronic Myeloid Leukemia.

BACKGROUND: Based on the new data from the primary analysis of the OPTIC (Optimizing Ponatinib Treatment in CP-CML) trial on dose optimization of ponatinib in patients with chronic phase (CP)-CML, the German consensus paper on ponatinib published in 2020 (Saussele S et al., Acta Haematol. 2020) has been updated in this addendum. SUMMARY: Focus is on the update of efficacy and safety of ponatinib, reflecting the new data set, as well as the update of the benefit-risk assessment and recommendations for ponatinib starting dose in CP-CML - provided that the decision to use ponatinib has already been made. Furthermore, based on OPTIC and additional empirical data, the expert panel collaborated to develop a decision tree for ponatinib dosing, specifically for intolerant and resistant patients. The recommendations on cardiovascular management have also been updated based on the most recent 2021 guidelines of the European Society of Cardiology (ESC) on cardiovascular disease prevention in clinical practice. KEY MESSAGES: The OPTIC data confirm the high efficacy of ponatinib in patients with CP-CML and provide the basis for individualized dose adjustment during the course of treatment.

[Treatment of hemophagocytic lymphohistiocytosis in patients in the intensive care unit]. / Behandlung der hämophagozytischen Lymphohistiozytose bei Patienten auf der Intensivstation.

Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome characterized by hyperferritinemia. A differentiation is made between hereditary and acquired forms. In contrast to children, almost all cases in adult patients consist of acquired secondary HLH. Infections, malignancies and autoimmune diseases are frequent triggers of secondary HLH. More recently, cases of HLH have also been described in association with immunotherapy, e.g., when using chimeric antigen receptor (CAR) T­cell treatment. In critically ill patients in the intensive care unit (ICU), sepsis represents the major differential diagnosis of HLH due to the frequently similar clinical presentation. Sometimes both sepsis and HLH are present at the same time. An early diagnosis and timely initiation of immunosuppressive treatment are essential for the further course and prognosis of HLH. Therefore, HLH should be considered as a possible diagnosis in critically ill patients with persistent fever and additional compatible symptoms (e.g., splenomegaly, neurological symptoms) or laboratory parameters (e.g., hyperferritinemia, cytopenia of two or three cell lines, increased transaminases). The diagnosis of HLH is made on the basis of the HLH-2004 criteria. The HScore can be used to estimate the probability of the presence of HLH. Corticosteroids given at high doses are the cornerstone of HLH treatment. Furthermore, immunoglobulins, etoposide, anakinra or ruxolitinib can complement treatment depending on the HLH trigger. The course of HLH depends on the timely initiation of treatment, the underlying trigger and the response to treatment. Despite progress in terms of diagnostics and targeted treatment, the prognosis of critically ill HLH patients is still poor.

[Paraneoplastic hyperleukocytosis in lung cancer]. / Paraneoplastische Hyperleukozytose bei Lungenkarzinom.

Paraneoplastic leukocytosis in solid tumors is associated with poor prognosis. While mild leukocytosis is common, paraneoplastic hyperleukocytosis is extremely rare. The case of a 73-year-old male diagnosed with an adenocarcinoma of the lung and a peak white blood cell count of 178,000/µl is reported. The patient succumbed to the disease after two cycles of immunochemotherapy only 2 months after first hospital admission. Specific treatment options are still under investigation and have not been reported in clinical use.

Hemophagocytic Syndrome-Associated Intravascular Large B-cell Lymphoma With Dialysis-Dependent End-Stage Renal Disease Treated With Autologous Stem Cell Transplantation Using a Modified TEAM Regimen.

Due to the low incidence and the large number of postmortem diagnoses, treatment recommendations for intravascular large B-cell lymphoma (IVLBCL) are largely based on retrospective studies and case reports. There is little data on autologous stem cell transplantation (ASCT) in dialysis-dependent patients and choosing an adequate regimen and dosing is difficult. Here, we report the treatment of a patient with relapsed IVLBCL and end-stage renal disease caused by lymphoma-associated renal AA amyloidosis using a modified TEAM (thiotepa, etoposide, cytarabine, and melphalan) regimen and ASCT. A 42-year-old female had an early relapse of hemophagocytic syndrome-associated intravascular large B-cell lymphoma resulting in terminal renal disease with dialysis dependency. Because of comorbidities (AA amyloidosis with severe hypoalbuminemia and end-stage renal disease), a modified, dose-reduced TEAM regimen was used as a high-dose conditioning regimen based on clinical pharmacologic considerations. The patient developed grade three mucositis and grade four febrile neutropenia as adverse events after transplantation. A modified TEAM regimen is feasible in a patient with end-stage renal disease with manageable toxicity. This is the first report of treatment with thiotepa in a dialysis-dependent patient.

Long-term efficacy, safety and neurotolerability of MATRix regimen followed by autologous transplant in primary CNS lymphoma: 7-year results of the IELSG32 randomized trial.

219 HIV-negative adults ≤70 years with primary CNS lymphoma (PCNSL) were enrolled in the randomized IELSG32 trial. Enrolled patients were randomly assigned to receive methotrexate-cytarabine (arm A), or methotrexate-cytarabine-rituximab (B), or methotrexate-cytarabine-thiotepa-rituximab (MATRix; arm C). A second randomization allocated patients with responsive/stable disease to whole-brain irradiation (WBRT) or carmustine-thiotepa-conditioned autologous transplantation (ASCT). First results, after a median follow-up of 30 months, showed that MATRix significantly improves outcome, with both WBRT and ASCT being similarly effective. However, sound assessment of overall survival (OS), efficacy of salvage therapy, late complications, secondary tumors, and cognitive impairment requires longer follow-up. Herein, we report the results of this trial at a median follow-up of 88 months. As main findings, MATRix was associated with excellent long-lasting outcome, with a 7-year OS of 21%, 37%, and 56% respectively for arms A, B, and C. Notably, patients treated with MATRix and consolidation had a 7-year OS of 70%. The superiority of arm B on arm A suggests a benefit from the addition of rituximab. Comparable efficacy of WBRT and ASCT was confirmed. Salvage therapy was ineffective; benefit was recorded only in patients with late relapse re-treated with methotrexate. Eight (4%) patients developed a second cancer. Importantly, MATRix and ASCT did not result in higher non-relapse mortality or second tumors incidence. Patients who received WBRT experienced impairment in attentiveness and executive functions, whereas patients undergoing ASCT experienced improvement in these functions as well as in memory and quality of life.

Consensus-Based Guidelines for the Recognition, Diagnosis, and Management of Hemophagocytic Lymphohistiocytosis in Critically Ill Children and Adults.

OBJECTIVE: Hemophagocytic lymphohistiocytosis is a hyperinflammatory syndrome that often requires critical care support and remains difficult to diagnose. These guidelines are meant to aid in the early recognition, diagnosis, supportive care, and treatment of patients with hemophagocytic lymphohistiocytosis in ICUs. DATA SOURCES: The literature searches were performed with PubMed (MEDLINE). STUDY SELECTION: Keywords and medical subject headings terms for literature search included "macrophage activation syndrome," hemophagocytic lymphohistiocytosis," and "hemophagocytic syndrome." DATA EXTRACTION: The Histiocyte Society developed these consensus recommendations on the basis of published reports and expert opinions with level of evidence provided for each recommendation. They were endorsed by the Society of Critical Care Medicine. DATA SYNTHESIS: Testing for hemophagocytic lymphohistiocytosis should be initiated promptly in all patients admitted to ICUs with an unexplained or disproportionate inflammatory response, especially those with rapid clinical deterioration. Meeting five or more of eight hemophagocytic lymphohistiocytosis 2004 diagnostic criteria serves as a valuable diagnostic tool for hemophagocytic lymphohistiocytosis. Early aggressive critical care interventions are often required to manage the multisystem organ failure associated with hemophagocytic lymphohistiocytosis. Thorough investigation of the underlying triggers of hemophagocytic lymphohistiocytosis, including infections, malignancies, and autoimmune/autoinflammatory diseases, is essential. Early steroid treatment is indicated for patients with familial hemophagocytic lymphohistiocytosis and is often valuable in patients with acquired hemophagocytic lymphohistiocytosis (i.e., secondary hemophagocytic lymphohistiocytosis) without previous therapy, including macrophage activation syndrome (hemophagocytic lymphohistiocytosis secondary to autoimmune/autoinflammatory disease) without persistent or relapsing disease. Steroid treatment should not be delayed, particularly if organ dysfunction is present. In patients with macrophage activation syndrome, whose disease does not sufficiently respond, interleukin-1 inhibition and/or cyclosporine A is recommended. In familial hemophagocytic lymphohistiocytosis and severe, persistent, or relapsing secondary macrophage activation syndrome, the addition of prompt individualized, age-adjusted etoposide treatment is recommended. CONCLUSIONS: Further studies are needed to determine optimal treatment for patients with hemophagocytic lymphohistiocytosis in ICUs, including the use of novel and adjunct therapies.

Differential Diagnosis of Hyperferritinemia in Critically Ill Patients.

BACKGROUND: Elevated serum ferritin is a common condition in critically ill patients. It is well known that hyperferritinemia constitutes a good biomarker for hemophagocytic lymphohistiocytosis (HLH) in critically ill patients. However, further differential diagnoses of hyperferritinemia in adult critically ill patients remain poorly investigated. We sought to systematically investigate hyperferritinemia in adult critically ill patients without HLH. METHODS: In this secondary analysis of a retrospective observational study, patients ≥18 years admitted to at least one adult intensive care unit at Charité-Universitätsmedizin Berlin between January 2006 and August 2018, and with hyperferritinemia of ≥500 µg/L were included. Patients with HLH were excluded. All patients were categorized into non-sepsis, sepsis, and septic shock. They were also classified into 17 disease groups, based on their ICD-10 codes, and pre-existing immunosuppression was determined. Uni- and multivariable linear regression analyses were performed in all patients. RESULTS: A total of 2583 patients were analyzed. Multivariable linear regression analysis revealed positive associations of maximum SOFA score, sepsis or septic shock, liver disease (except hepatitis), and hematological malignancy with maximum ferritin. T/NK cell lymphoma, acute myeloblastic leukemia, Kaposi's sarcoma, acute or subacute liver failure, and hepatic veno-occlusive disease were positively associated with maximum ferritin in post-hoc multivariable linear regression analysis. CONCLUSIONS: Sepsis or septic shock, liver disease (except hepatitis) and hematological malignancy are important differential diagnoses in hyperferritinemic adult critically ill patients without HLH. Together with HLH, they complete the quartet of important differential diagnoses of hyperferritinemia in adult critically ill patients. As these conditions are also related to HLH, it is important to apply HLH-2004 criteria for exclusion of HLH in hyperferritinemic patients. Hyperferritinemic critically ill patients without HLH require quick investigation of differential diagnoses.

[Hemophagocytic lymphohistiocytosis in critically ill patients]. / Die hämophagozytische Lymphohistiozytose bei kritisch kranken Patienten.

Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammation syndrome. In adults, secondary HLH is mostly observed. HLH is often triggered by infections, malignancies or autoimmune disorders. However, HLH cases in association with immunotherapies have been described recently. HLH in critically ill patients is often difficult to differentiate from sepsis. Both conditions can also be present at the same time. Early diagnosis and timely initiation of an adequate immunosuppressive therapy are essential for the further course and the prognosis of HLH. Therefore, HLH should represent a differential diagnosis in critically ill patients with persistent fever and additional symptoms (e.g. enlarged spleen, neurologic symptoms) or laboratory parameters (e.g. hyperferritinemia, cytopenia, increased transaminases) compatible with HLH. The diagnosis of HLH is made using the HLH-2004 criteria. The probability of the presence of HLH can be calculated using the HScore. High-dose corticosteroids represent the cornerstone of HLH treatment. Etoposide, immunoglobulins, anakinra or other drugs are added depending on the trigger. The course of HLH is influenced by the time of treatment initiation, the underlying trigger and the response to treatment. Generally, the prognosis of critically ill HLH patients is poor.

The mTOR Inhibitor Temsirolimus Added to Rituximab Combined With Dexamethasone, Cytarabine, and Cisplatinum (R-DHAP) for the Treatment of Patients With Relapsed or Refractory DLBCL - Results From the Phase-II STORM Trial.

There is a high need for novel treatment options in relapsed and refractory diffuse large B-cell lymphoma. Single agent mammalian target of rapamycin (mTOR) inhibitor treatment has shown promising efficacy in this entity. Here, we report on the results of the mTOR-inhibitor temsirolimus combined to standard rituximab-DHAP salvage regimen in a prospective, multicenter, phase II, open-label study. The STORM regimen consisted of rituximab 375 mg/m2 (day 2) and DHAP (dexamethasone 40 mg day 3-6, cisplatinum 100 mg/m2 day 3, cytarabine 2 × 2 g/m2 day 4) with temsirolimus added on day 1 and 8 of a 21-day cycle, with 2 to 4 cycles planned. In part I, dose levels of 25, 50, 75, and 100 mg for temsirolimus were predefined. Based on the observed toxicity profile, a temsirolimus dose of 25 mg was defined as recommended dose for the part II extension cohort of the trial. The intention-to-treat cohort comprised 53 patients. Median age was 63 years and median number of prior regimen was 1. All but 1 patient had prior rituximab exposure. Temsirolimus dose was 50 mg on day 1 and 8 in 6 patients from the part I of the trial and 25 mg in the remaining 47 patients. In general, treatment was well tolerated with leucopenia and thrombocytopenia as most frequent severe adverse events. The overall response rate after the last cycle of temsirolimus R-DHAP was 66% with 24% complete responses. The ability to mobilize stem cells was not impaired by the treatment regimen. Twenty-eight patients received consolidation treatment with high-dose therapy (HDT) and stem cell transplantation. Median duration of response was not reached. The total 2-year progression-free survival (PFS) and overall survival (OS) were 53% and 59%. Patients who were consolidated with HDT achieved a 2-year PFS and a 2-year OS of 77.8% and 82.1%, respectively. We conclude that temsirolimus can be safely added to rituximab and DHAP with promising activity.

Influence of transfusions, hemodialysis and extracorporeal life support on hyperferritinemia in critically ill patients.

BACKGROUND: Ferritin is the major iron storage protein and an acute phase reactant. Hyperferritinemia is frequently seen in the critically ill where it has been hypothesized that not only underlying conditions but also factors such as transfusions, hemodialysis and extracorporeal life support (ECLS) lead to hyperferritinemia. This study aims to investigate the influence of transfusions, hemodialysis, and ECLS on hyperferritinemia in a multidisciplinary ICU cohort. METHODS: This is a post-hoc analysis of a retrospective observational study including patients aged ≥ 18 years who were admitted to at least one adult ICU between January 2006 and August 2018 with hyperferritinemia ≥ 500 µg/L and of ≥ 14 days between two ICU ferritin measurements. Patients with hemophagocytic lymphohistiocytosis (HLH) were excluded. To identify the influence of transfusions, hemodialysis, and ECLS on ferritin change, multivariable linear regression analysis with ferritin change between two measurements as dependent variable was performed. RESULTS: A total of 268 patients was analyzed. Median duration between measurements was 36 days (22-57). Over all patients, ferritin significantly increased between the first and last measurement (p = 0.006). Multivariable linear regression analysis showed no effect of transfusions, hemodialysis, or ECLS on ferritin change. Changes in aspartate aminotransferase (ASAT) and sequential organ failure assessment (SOFA) score were identified as influencing factors on ferritin change [unstandardized regression coefficient (B) = 2.6; (95% confidence interval (CI) 1.9, 3.3); p < 0.001 and B = 376.5; (95% CI 113.8, 639.1); p = 0.005, respectively]. Using the same model for subgroups of SOFA score, we found SOFA platelet count to be associated with ferritin change [B = 1729.3; (95% CI 466.8, 2991.9); p = 0.007]. No association of ferritin change and in-hospital mortality was seen in multivariable analysis. CONCLUSIONS: The present study demonstrates that transfusions, hemodialysis, and ECLS had no influence on ferritin increases in critically ill patients. Hyperferritinemia appears to be less the result of iatrogenic influences in the ICU thereby underscoring its unskewed diagnostic value. TRIAL REGISTRATION: The study was registered with www.ClinicalTrials.gov (NCT02854943) on August 1, 2016.

Case Report: Hemophagocytic Lymphohistiocytosis and Non-Tuberculous Mycobacteriosis Caused by a Novel GATA2 Variant.

Hemophagocytic lymphohistiocytosis (HLH) is a disorder of uncontrolled immune activation with distinct clinical features including fever, cytopenia, splenomegaly, and sepsis-like symptoms. In a young adolescent patient a novel germline GATA2 variant (NM_032638.5 (GATA2): c.177C>G, p.Tyr59Ter) was discovered and had resulted in non-tuberculous mycobacterial (NTM) infection and aggressive HLH. Strikingly, impaired degranulation of cytotoxic T-lymphocytes (CTL) and natural killer (NK)-cells was detected in CD107a-analyses. The affected patient was treated with HLA-matched unrelated alloHSCT, and subsequently all hematologic and infectious abnormalities including HLH and NTM resolved. This case supports early alloHSCT in GATA2 deficiencies as curative approach regardless of active NTM infection. Future studies on GATA2 c.177C>G, p.Tyr59*Ter might unravel its potential role in cytotoxic effector cell function and its contribution to HLH pathogenesis.

Combination of Lenvatinib and Pembrolizumab Is an Effective Treatment Option for Anaplastic and Poorly Differentiated Thyroid Carcinoma.

Background: Anaplastic thyroid carcinoma (ATC) and metastatic poorly differentiated thyroid carcinomas (PDTCs) are rare aggressive malignancies with poor overall survival (OS) despite extensive multimodal therapy. These tumors are highly proliferative, with frequently increased tumor mutational burden (TMB) compared with differentiated thyroid carcinomas, and elevated programmed death ligand 1 (PD-L1) levels. These tumor properties implicate responsiveness to antiangiogenic and antiproliferative multikinase inhibitors such as lenvatinib, and immune checkpoint inhibitors such as pembrolizumab. Patients and Methods: In a retrospective study, we analyzed six patients with metastatic ATC and two patients with PDTC, who received a combination therapy of lenvatinib and pembrolizumab. Lenvatinib was started at 14-24 mg daily and combined with pembrolizumab at a fixed dose of 200 mg every three weeks. Maximum treatment duration with this combination was 40 months, and 3 of 6 ATC patients are still on therapy. Patient tumors were characterized by whole-exome sequencing and PD-L1 expression levels (tumor proportion score [TPS] 1-90%). Results: Best overall response (BOR) within ATCs was 66% complete remissions (4/6 CR), 16% stable disease (1/6 SD), and 16% progressive disease (1/6 PD). BOR within PDTCs was partial remission (PR 2/2). The median progression-free survival was 17.75 months for all patients, and 16.5 months for ATCs, with treatment durations ranging from 1 to 40 months (1, 4, 11, 15, 19, 25, 27, and 40 months). Grade III/IV toxicities developed in 4 of 8 patients, requiring dose reduction/discontinuation of lenvatinib. The median OS was 18.5 months, with three ATC patients being still alive without relapse (40, 27, and 19 months) despite metastatic disease at the time of treatment initiation (UICC and stage IVC). All patients with long-term (>2 years) or complete responses (CRs) had either increased TMB or a PD-L1 TPS >50%. Conclusions: Our results implicate that the combination of lenvatinib and pembrolizumab might be safe and effective in patients with ATC/PDTC and can result in complete and long-term remissions. The combination treatment is now being systematically examined in a phase II clinical trial (Anaplastic Thyroid Carcinoma Lenvatinib Pembrolizumab [ATLEP]) in ATC/PDTC patients.