Efficacy of a third BNT162b2 mRNA COVID-19 vaccine dose in patients with CLL who failed standard 2-dose vaccination.

Patients with chronic lymphocytic leukemia (CLL) have an impaired antibody response to coronavirus disease 2019 (COVID-19) vaccination. Here, we evaluated the antibody response to a third BNT162b2 mRNA vaccine in patients with CLL/small lymphocytic lymphoma (SLL) who failed to achieve a humoral response after standard 2-dose vaccination regimen. Anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies were measured 3 weeks after administration of the third dose. In 172 patients with CLL, the antibody response rate was 23.8%. Response rate among actively treated patients (12.0%; n = 12/100) was lower compared with treatment-naïve patients (40.0%; n = 16/40; OR = 4.9, 95% CI 1.9-12.9; P < .001) and patients off-therapy (40.6%; n = 13/32; OR = 5.0, 95% CI 1.8-14.1; P < .001), (P < .001). In patients actively treated with Bruton's tyrosine kinase (BTK) inhibitors or venetoclax ± anti-CD20 antibody, response rates were extremely low (15.3%, n = 9/59, and 7.7%, n = 3/39, respectively). Only 1 of the 28 patients (3.6%) treated with anti-CD20 antibodies <12 months prior to vaccination responded. In a multivariate analysis, the independent variables that were associated with response included lack of active therapy (OR = 5.6, 95% CI 2.3-13.8; P < .001) and serum immunoglobulin A levels ≥80 mg/dL (OR = 5.8, 95% CI 2.1-15.9; P < .001). In patients with CLL/SLL who failed to achieve a humoral response after standard 2-dose BNT162b2 mRNA vaccination regimen, close to a quarter responded to the third dose of vaccine. The antibody response rates were lower during active treatment and in patients with a recent exposure (<12 months prior to vaccination) to anti-CD20 therapy. This trial was registered at www.clinicaltrials.gov as #NCT04862806.

Safety and efficacy of the BNT162b mRNA COVID-19 vaccine in patients with chronic lymphocytic leukemia.

Patients with chronic lymphocytic leukemia (CLL) have a suboptimal humoral response to vaccination. Recently, BNT162b2, an mRNA COVID-19 vaccine with a high efficacy of 95% in immunocompetent individuals, was introduced. We investigated the safety and efficacy of the BNT162b2 mRNA COVID-19 vaccine in patients with CLL from nine medical centers in Israel, Overall 400 patients were included, of whom 373 were found to be eligible for the analysis of antibody response. The vaccine appeared to be safe and only grade 1-2 adverse events were seen in 50% of the patients. Following the second dose, an antibody response was detected in 43% of the cohort. Among these CLL patients, 61% of the treatment-na ve patients responded to the vaccine, while responses developed in only 18% of those with ongoing disease, 37% of those previously treated with a BTK inhibitor and 5% of those recently given an anti-CD20 antibody. Among patients treated with BCL2 as monotherapy or in combination with anti-CD20, 62% and 14%, respectively, developed an immune response. There was a high concordance between neutralizing antibodies and positive serological response to spike protein. Based on our findings we developed a simple seven-factor score including timing of any treatment with anti-CD20, age, treatment status, and IgG, IgA, IgM and hemoglobin levels. The sum of all the above parameters can serve as a possible estimate to predict whether a given CLL patient will develop sufficient antibodies. In conclusion, the BNT162b2 mRNA COVID-19 vaccine was found to be safe in patients with CLL, but its efficacy is limited, particularly in treated patients.

Polatuzumab-based regimen or CAR T cell for patients with refractory/relapsed DLBCL-a matched cohort analysis.

Polatuzumab (Pola)-based regimens and chimeric antigen receptor T (CAR T) cells provide superior outcome compared to conventional chemoimmunotherapy in patients with relapsed/refractory diffuse large B cell lymphoma (R/R DLBCL). Choosing between these strategies remains controversial. The efficacy of CAR T versus Pola-rituximab(R) /Pola-bendamustine(B)-R in R/R DLBCL patients after failing ≥2 lines of treatment was compared in a retrospective, 'real-world' study. Propensity score matching, for age, lymphoma category (de-novo/transformed), number of prior lines, Eastern Cooperative Oncology Group performance status and lactate dehydrogenase level, was applied to control for differences in patients' characteristics. Response rate, progression-free survival (PFS) and overall survival (OS) were analyzed. A total of 82 patients, treated with CAR T (n=41) or Pola-based regimens (n=41), were included. No treatment-related deaths occurred with CAR T vs. 3 (7.3%) with Pola. The overall and complete response rates were 83% and 58% with CAR T vs. 66% and 44% with Pola-based-regimens (p=0.077 and p=0.18, respectively). At a median follow-up of 9 months (range 1-19.2) and 16 months (range 0.7-25.3) for the CAR T and Pola arm respectively, the median PFS has not been reached for CAR T vs. 5.6 months for Pola (95% CI 3.6-7.6, p=0.014). Median OS has not been reached for CAR T vs. 10.8 months (95% CI 2.2-19.4) for Pola (p=0.026). To conclude, in a real-world setting, treatment with CAR T achieved superior PFS and OS compared to Pola-based regimens in patients with R/R DLBCL.

Management and Outcome of Venous Thrombosis in Patients with Myeloproliferative Neoplasms: Data from the Israeli MPN Working Group.

The BCR-ABL-negative myeloproliferative neoplasms (MPN) are associated with high incidence of venous thrombosis and a significant rate of recurrent events, but there is no consensus regarding their management. In this retrospective study, we analyzed 96 patients with MPN-related venous thrombosis. The index venous thrombosis occurred at a median age of 58 years (IQR 37-71), with 58% of the events involving unusual sites. Patients who were on antiplatelet agents at the time of index thrombosis tended to be older than patients who were not receiving antiplatelets at the time of index thrombosis. The majority of index thromboses occurring after the diagnosis of MPN had uncontrolled blood counts at the time of event and were not receiving antithrombotic agents. Following the thrombotic episode, 75% of patients received long-term anticoagulation. At a median follow-up of 3.4 years, the recurrence rate was 14%. Thrombophilia was significantly more prevalent among patients with recurrent thrombosis compared to patients without recurrence (p < 0.01). Patients who developed a recurrent event early were more likely to have thrombophilia (either inherited or antiphospholipid antibodies), and controlled blood counts, and were likely to receive anticoagulation at the time of recurrence compared to patients with later recurrences. Thrombophilia may contribute to venous thrombosis recurrence, especially early after the index venous thrombosis. Suboptimal anticoagulation and blood count control are factors associated with late venous thrombosis recurrence.

Willingness and concerns of transfusion-dependent hematological patients toward the option of home transfusion therapy.

BACKGROUND: One of the main obstacles of providing home-based palliative care to transfusion-dependent hematology patients is the lack of home transfusions services. While healthcare professionals are concerned with safety and cost of home transfusions, the attitude of the patients toward home transfusions are mostly unknown. AIM: To obtain quantitative data regarding the willingness and concerns of transfusion-dependent patients with hematological diseases toward the option of home transfusions. DESIGN: A cross sectional survey including a self-administered questionnaire in one of the three main spoken languages in Israel was administered to patients in 17 hospital hematology outpatient clinics between May 2019 and March 2020. RESULTS: About 52% of 385 patients that participated in the survey preferred home transfusions to hospital transfusions. Gender, age, education, or type of disease were not associated with preference for home transfusions, nor were hospital location or its size. The likelihood to prefer home transfusions was significantly higher among the Hebrew-speakers and those who had not experienced adverse effects previously. The most significant factor associated with preference of home transfusions was a perceived negative effect of hospital-based transfusion on quality of life. The main reason to reject home transfusions was fear of possible adverse effects and concerns over losing contact with the medical staff at the treating hospital. CONCLUSION: These data suggest that a significant portion of transfusion-dependent patients in Israel view home transfusions as a preferred treatment option and that its successful implementation requires maintaining ongoing contact with the treating hospital.

Characteristics and outcomes of young adults with Philadelphia-negative myeloproliferative neoplasms.

OBJECTIVE: Approximately 10% of Philadelphia (Ph)-negative myeloproliferative neoplasms (NPM) are diagnosed at young adulthood. We aim to define the features of this group. METHODS: A multicenter retrospective study, including patients 18-45 years of age, diagnosed with Ph-negative MPN between 1985 and 2017. RESULTS: One hundred nine patients were included, 37 with polycythemia vera (34%), 54 with essential thrombocytosis (50%), 15 with primary myelofibrosis (PMF) (14%), and 3 with MPN unclassifiable (3%). Median age was 33 years and 62 (57%) were females. During a median follow-up of 8 years, 39 patients (37%) had at least one thrombotic event. 30/39 of events were venous (77%), 23/30 of which were splanchnic (77%). In 14/39 (36%), thrombosis preceded MPN diagnosis. In a multivariable analysis, only splenomegaly predicted for thrombosis (HR 5.6, CI: 1.4-22). The 10-year risk for secondary myelofibrosis was similar for ET and PV (0.13 vs 0.19, P = 0.51). The 10-year risk for leukemic transformation or mortality was significantly higher for PMF (0.3, P = 0.04). CONCLUSIONS: The risks of mortality and of progression to MF/leukemia in young adults are similar to older population. Thrombotic events are frequently a presenting sign with a high incidence of venous, in particular splanchnic, events.

A New Take on a Resource-Based Model of Quality of Life in Hemato-Oncological Patients: Demographic, Personal, and Social Factors.

This study tests a new comprehensive model accounting for the role of demographic, personal, and social factors in quality of life (QOL) among a sample of hematological cancer patients. We hypothesized that positive and negative affect would mediate the associations between these factors and QOL. Seventy-two patients were recruited at an outpatient hematological clinic in a midsized medical center in northern Israel. They completed measures of QOL, social support, positive and negative affect, and emotional intelligence (EI). Diagnostic and demographic information was retrieved from their files. Path analysis supported a model in which positive and negative affect mediated the association between income level, social support, EI, and QOL. This study presents a model accounting for QOL among hematological patients that for the first time pertains to demographic, personal, and interpersonal factors. This model may guide future research as well as future interventions to empower and support this fragile target population.

[PREGNANCY RELATED ACQUIRED HEMOPHILIA A].

INTRODUCTION: Acquired hemophilia A is a rare disease. The incidence has been estimated to be 1.3-1.5 cases per 1 million persons per year. The etiology of acquired hemophilia A varies. It may develop in patients with autoimmune disorders, hematologic and solid cancers or in women during pregnancy or following childbirth. In about half of the cases no underlying disease can be found. The clinical picture is dominated by severe soft tissue hematomas especially in the cases of pregnancy-related acquired hemophilia A. Unlike congenital hemophilia A, bleeding into joints is rare. Pregnancy-related acquired hemophilia A may develop following any pregnancy but is observed more often in primigravidas. In most cases it arises in the postpartum period, most commonly 1-4 months after delivery. If factor VIII inhibitors develop during pregnancy or labor, they are frequently associated with severe uterine bleeding. The prognosis of pregnancy-related acquired hemophilia A is good with a high percentage of spontaneous remissions especially if the inhibitor was detected postpartum. Patients with acquired inhibitors do not usually have personal or family history of bleeding tendency, thus it is the presence of bleeding at multiple sites with prolonged activated partial thromboplastin time not corrected by incubation with normal plasma (mixing study) that raises the suspicion of inhibitor. Prompt diagnosis and treatment achieved by close collaboration among gynecologists and hematologists may improve the prognosis and prevent severe bleeding.

Analysis of the First 100 Patients From the Syrian Civil War Treated in an Israeli District Hospital.

OBJECTIVE: An analysis of the injuries and treatment of the first 100 patients from the Syrian civil war was conducted to monitor quality of care and outcome. SUMMARY BACKGROUND DATA: As reports of the collapse of health care systems in regions within Syria reach the media, patients find themselves crossing the border into Israel for the treatment of war injuries. Among these patients are combatants, noncombatants, women, and children. Treatment, that is free at the point of care, is a humanitarian imperative for war wounded, and this paper reports the care in an Israeli district hospital of the first 100 patients received. METHODS: With ethics committee approval, data from the Trauma Registry and electronic patient records were collected and analyzed. No identifying data are presented. RESULTS: Most patients (94) were male. Seventeen patients were younger than the age of 18 years; 52 patients were in their twenties. Most injuries were the results of gunshot or blast injury (50 and 29 patients, respectively). Two multiple-trauma patients died, 8 were transferred for specialist care, and 90 patients returned from Ziv Hospital to Syria after discharge. CONCLUSIONS: The experience of the care of patients across a hostile border has been unprecedented. Hospital protocols required adjustment to deliver quality clinical and social care to patients suffering from both the acute and chronic effects of civil war.

Outcomes of light-chain amyloidosis patients treated with first-line bortezomib: a collaborative retrospective multicenter assessment.

Light-chain amyloidosis (AL) is associated with low survival rates, particularly in patients with cardiac involvement. We evaluated the outcome of 73 consecutive, non-selected 'real-world' AL patients, treated with first-line bortezomib-based induction, focusing on the benefit of concurrent administration of alkylating agents. Most patients had renal (77%), cardiac (66%), or multiorgan (74%) involvement. Sixty-eight per cent (n = 50) received alkylating agent (mostly cyclophosphamide). Severe adverse events were seen in 45%, most evident in patients with cardiac involvement, with no increased toxicity in patients receiving an alkylator agent. Hematological response (HemR) was obtained in 77% of patients, including 33% very good partial responses and 19% complete responses. Age <70 yr, lack of cardiac and peripheral neurologic involvement, and co-administration of an alkylating agent were associated with significantly improved HemR. NYHA cardiac failure staging was the only independent factor affecting overall survival. Administration of an alkylating agent and the achievement of both HemR and organ response were associated with a statistically significant improved survival in those surviving the first 6 months of induction. First-line bortezomib-based regimen resulted in favorable response and survival in newly diagnosed patients. Co-administration of an alkylating agent improved outcome without increasing treatment-related toxicity.

[MICROANGIOPATHIC HEMOLYTIC ANEMIA AS PRESENTING SYMPTOM OF GASTRIC ADENOCARCINOMA].

Metastatic adenocarcinoma presenting as microangiopathic hemolytic anemia (MAHA) is a rare finding. We report the case of a young patient who presented with MAHA as the initial symptom of metastatic gastric adenocarcinoma. Cancer-related microangiopathic hemolytic anemia is a paraneoplastic syndrome characterized by Coombs-negative hemolytic anemia with schistocytes and thrombocytopenia. A high index of suspicion and prompt diagnosis can prevent ulterior deterioration, especially when chemotherapy is the optimal treatment in these cases, which can stop the hemolysis.

Efficacy and safety of Apixaban in the treatment of cerebral venous sinus thrombosis: a multi-center study.

Background: Information regarding the safety and efficacy of specific direct oral anticoagulants (DOAC) in the treatment of cerebral sinus and venous thrombosis (CSVT) is scarce. Apixaban is one of the most frequently prescribed DOACs. Therefore, we aimed to compare the safety and efficacy of Apixaban with those of vitamin k antagonists (VKA) in patients with CSVT. Methods: Prospective CSVT databases from seven academic medical centers were retrospectively analyzed. Patients treated with Apixaban were compared to those treated with VKA. Data on demographics, clinical presentations, risk factors, radiological and outcome parameters were studied. Results: Overall, 403 patients were included in the analysis. Of them, 48 (12%) were treated with Apixaban, and 355 (88%) were treated with VKA. Rates of coagulopathies were significantly higher in the VKA-treated patients but no other differences between the groups were found in baseline characteristics and underlying etiology. No significant differences were found between groups in efficacy or safety parameters including the rates of recanalization, favorable outcomes, one-year mortality, seizures, intracranial hemorrhage or CSVT recurrences. Conclusion: Our data suggests that Apixaban may be safe and effective for patients with CSVT. These results should be tested in prospective randomized clinical studies.

Predicting infections in high-risk patients with myelodysplastic syndrome/acute myeloid leukemia treated with azacitidine: a retrospective multicenter study.

Hypomethylating agents have become the standard therapy for patients with high-risk myelodysplastic syndrome (MDS). In Israel, azacitidine (AZA) is routinely used. Yet, infectious complications are common during AZA therapy. The current study was aimed to evaluate the incidence and predisposing risk factors for infections in AZA-treated patients. This retrospective study included patients treated with AZA in 18 Israeli medical institutions between 2008 and 2011. Data on 184 patients [157 high-risk MDS and 27 acute myeloid leukemia (AML)], with a median age of 71.6 (range 29-92) were recorded. Overall, 153 infectious events were reported during 928 treatment cycles (16.5%) administered to 100 patients. One hundred fourteen, 114/153 (75%) events required hospitalization and 30 (19.6%) were fatal. In a univariate analysis, unfavorable cytogenetics, low neutrophil, hemoglobin (Hb) and platelet (PLT) counts were found to be associated with infections (24.4% vs. 12.9%, P < 0.0001; 27% vs. 13.5%, P < 0.0001; 20.4% vs. 11%, P < 0.0001 and 29.2% vs. 14.2%, P < 0.0001, respectively). In multivariate analysis, only low Hb level, low PLT count, and unfavorable cytogenetics remained significant. Prior to therapy, poor cytogenetics, PLT count below 20 × 109/L and neutrophil count below 0.5 × 109/L were predictive of the risk of infection during the first two cycles of therapy. In conclusion, patients with unfavorable cytogenetics, presenting with low neutrophil and PLT counts, are susceptible to infections. Evaluation of infection risk should be repeated prior to each cycle. Patients with poor cytogenetics in whom AZA is prescribed despite low PLT count are particularly at high risk for infections and infection prophylaxis may be considered.

Ethnic disparities in presentation but not outcome in multiple myeloma patients: a multicenter retrospective study in Northern Israel.

Several studies showed ethnic disparities in multiple myeloma (MM) incidence and prognosis. In order to compare prognosis and overall survival between different ethnic groups, a multicenter retrospective study was conducted in Northern Israel. A total of 145 patients suffering from MM were included (72% Jewish, and 28% Arabs) who were treated between 2008-2018. A difference was found in the stage of the disease at the time of diagnosis, patients of Arab origin were diagnosed at a more advanced stage (III), (53.7% vs. 33.7%, respectively). A mortality rate of 48.9% was found in the study, regardless of population ethnic origin. No significant differences in rates of MGUS, MM symptoms, treatments, or progression-free survival (PFS) and overall survival (OS) were observed between ethnic groups. This suggests that raising awareness of MM may result in an earlier diagnosis, especially among patients of Arab origin, preventing unnecessary suffering from these patients.

MDS-Related Anemia Is Associated with Impaired Quality of Life but Improvement Is Not Always Achieved by Increased Hemoglobin Level.

Quality of life is impaired in MDS, but the role of hemoglobin level is unclear. To study the Hb-QoL correlation at diagnosis and 1 year later, patients filled out the EQ-5D questionnaire, assessing their mobility, self care, daily activities, pain/discomfort, and anxiety/depression, using scores of 0 (normal), 1 (mild/moderate), or 2 (poor). They also evaluated their health using a visual analogue scale, scoring from 0 (poor) to 100 (excellent). The anemia subgroups were: none/normal (Hb ≥ 12.5 g/dL), mild (10 ≤ Hb < 12.5), moderate (9 ≤ Hb < 10), severe (8 ≤ Hb < 9), or very severe (Hb < 8). LR-MDS patients (n = 127) and inpatient controls (n = 141) participated. The anemic patients had a poor QoL and the MDS patients had a lower QoL with a lower Hb. The controls had no QoL difference among the various anemia subgroups. In addition, the MDS QoL sharply decreased with an Hb of < 9. The MDS patients showed a wide QoL variability, i.e., different QoL scores in the same Hb subgroup, suggesting that other factors affect QoL (e.g., age and comorbidities). After 1 year (n = 61), the QoL was still poor for most MDS patients (including 27 patients with an increased Hb). In summary: (1) a poor QoL in MDS-anemia is non-linear, suggesting other influencing factors on QoL. (2) The sharp QoL drop with Hb < 9 g/dL challenges the transfusion Hb threshold. (3) The QoL in anemic MDS patients might differ from that in non-MDS patients. (4) Raising Hb, while recommended, does not guarantee an improved QoL.

Differentiating ischemic from non-ischemic chest pain using white blood cell-surface inflammatory and coagulation markers.

Chest pain is one of the most common complaints seen in emergency departments (ED), up to 5-8 % of all ED visits. About 50-60 % of chest pain patients presenting to the ED are hospitalized. Seventy percentage of those patients not discharged from the ED are subsequently shown to not have acute cardiac disease. It has been estimated that emergency physician miss 2-6 % of acute coronary syndrome (ACS) that present to ED. While admitting a non-ACS patient is a financial burden on the medical system, releasing to home an undiagnosed ACS patient has life-threatening consequences. This study used flow cytometry to evaluate a panel of mononuclear cells, neutrophils, cytokines and fibrinolytic activation markers in patients presenting in ED with acute chest pain. The goal was to add diagnostic tools to the differentiation between true ischemic cardiac and non-ischemic chest pain in the process of triage. The study population consisted of 74 consecutive patients presenting with acute chest pain to the emergency department of Ziv Medical Center and were admitted to Intensive Cardiac Care Unit or Internal Wards of our hospital during the period September 2009 to February 2010. ACS has been clearly associated with a decrease in CD89+/CD62L+ population, an increase in percentage of cytotoxic T-cell subset, and an increase in platelet marker. Differences in thrombin receptor surface expression were also noted. The combination of multiple biomarkers may help to enhance diagnostic accuracy.

Non-immune Hemolysis in Gaucher Disease and Review of the Literature.

Gaucher disease (GD) is an autosomal recessive disease characterized by the buildup of glucocerebrosides in macrophages, resulting in the formation of "Gaucher cells." These cells predominantly infiltrate the liver, spleen, and bone marrow leading to hepatosplenomegaly, cytopenia, and bone pain. Anemia in GD is typically considered to result from non-hemolytic processes. Although rare, a higher rate of hemolytic anemia of the autoimmune type has been reported in GD than in the general population. The literature on non-immune hemolytic anemia in GD is scarce. We review the literature on hemolytic anemia in GD and report on a case of non-immune hemolytic anemia secondary to GD. We believe this is the first description of a patient with confirmed GD and symptomatic non-immune hemolytic anemia that responded to GD-specific treatment.

Identification of resistance pathways and therapeutic targets in relapsed multiple myeloma patients through single-cell sequencing.

Multiple myeloma (MM) is a neoplastic plasma-cell disorder characterized by clonal proliferation of malignant plasma cells. Despite extensive research, disease heterogeneity within and between treatment-resistant patients is poorly characterized. In the present study, we conduct a prospective, multicenter, single-arm clinical trial (NCT04065789), combined with longitudinal single-cell RNA-sequencing (scRNA-seq) to study the molecular dynamics of MM resistance mechanisms. Newly diagnosed MM patients (41), who either failed to respond or experienced early relapse after a bortezomib-containing induction regimen, were enrolled to evaluate the safety and efficacy of a daratumumab, carfilzomib, lenalidomide and dexamethasone combination. The primary clinical endpoint was safety and tolerability. Secondary endpoints included overall response rate, progression-free survival and overall survival. Treatment was safe and well tolerated; deep and durable responses were achieved. In prespecified exploratory analyses, comparison of 41 primary refractory and early relapsed patients, with 11 healthy subjects and 15 newly diagnosed MM patients, revealed new MM molecular pathways of resistance, including hypoxia tolerance, protein folding and mitochondria respiration, which generalized to larger clinical cohorts (CoMMpass). We found peptidylprolyl isomerase A (PPIA), a central enzyme in the protein-folding response pathway, as a potential new target for resistant MM. CRISPR-Cas9 deletion of PPIA or inhibition of PPIA with a small molecule inhibitor (ciclosporin) significantly sensitizes MM tumor cells to proteasome inhibitors. Together, our study defines a roadmap for integrating scRNA-seq in clinical trials, identifies a signature of highly resistant MM patients and discovers PPIA as a potent therapeutic target for these tumors.

A C5a-Immunoglobulin complex in chronic lymphocytic leukemia patients is associated with decreased complement activity.

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in the Western world. The therapeutic approach to CLL includes chemotherapeutic regimens and immunotherapy. Complement-mediated cytotoxicity, which is one of the mechanisms activated by the therapeutic monoclonal antibodies, depends on the availability and activity of the complement (C) system. The aim was to study the structure of circulating C components and evaluate the importance of C5 structural integrity for C activity in CLL patients. Blood samples were collected from 40 naïve CLL patients and 15 normal controls (NC). The Western blot analysis showed abnormal C5 pattern in some CLL patients, while patterns of C3 and C4 were similar in all subjects. Levels of the C activation markers sC5b-9 and C5a were quantified before and after activation via the classical (CP) and alternative (AP) pathways. In patients with abnormal C5, basal levels of sC5b-9 and C5a were increased while activities of the CP and of the CP C5-convertase, the immediate C5-upstream complex, were decreased compared to NC and to patients with normal C5. The data indicate a link between CP activation and apparent C5 alterations in CLL. This provides a potential prognostic tool that may personalize therapy by identifying a sub-group of CLL patients who display an abnormal C5 pattern, high basal levels of sC5b-9 and C5a, and impaired CP activity, and are likely to be less responsive to immunotherapy due to compromised CP activity.