Randomized phase 2 trial of ixazomib and dexamethasone in relapsed multiple myeloma not refractory to bortezomib.

Proteasome inhibitors have become an integral part of myeloma therapy. Considerable efforts have gone into optimizing this therapeutic approach to obtain maximal proteasome inhibition with least toxicity. Ixazomib is the first oral proteasome inhibitor to enter the clinic and has been studied as a single agent as well as in various combinations. The current trial was designed to examine the efficacy and toxicity of combining 2 different doses of ixazomib (4 mg and 5.5 mg given weekly for 3 of 4 weeks) with 40 mg weekly of dexamethasone, in relapsed myeloma. Seventy patients were enrolled, 35 patients randomly assigned to each ixazomib dose. Overall, 30 (43%; 95% confidence interval, 31-55) of the patients achieved a confirmed partial response or better, with 31% achieving a response with 4 mg and 54% with 5.5 mg of ixazomib. The median event-free survival (EFS) for the entire study population was 8.4 months; 1-year overall survival was 96%. The EFS was 5.7 months for patients with prior bortezomib exposure and 11.0 months for bortezomib-naïve patients. A grade 3 or 4 adverse event considered at least possibly related to treatment was seen in 11 (32%) patients at 4 mg and in 21 (60%) at 5.5 mg. Dose reductions were more frequent with 5.5 mg dose. Overall, the ixazomib with dexamethasone has good efficacy in relapsed myeloma, is well-tolerated and with higher response rate at 5.5 mg, albeit with more toxicity. This study was registered at www.clinicaltrials.gov as #NCT01415882.

Diagnosis and Management of Genetic Iron Overload Disorders.

Iron overload disorders lead to excess iron deposition in the body, which can occur as a result of genetic or secondary causes. Genetic iron overload, referred to as hereditary hemochromatosis, may present as a common autosomal recessive mutation or as one of several uncommon mutations. Secondary iron overload may result from frequent blood transfusions, exogenous iron intake, or certain hematological diseases such as dyserythropoietic syndrome or chronic hemolytic anemia. Iron overload may be asymptomatic, or may present with significant diseases of the liver, heart, endocrine glands, joints, or other organs. If treated appropriately prior to end-organ damage, life expectancy has been shown to be similar compared to matched populations. Alongside clinical assessment, diagnostic studies involve blood tests, imaging, and in some cases liver biopsy. The mainstay of therapy is periodic phlebotomy, although oral chelation is an option for selected patients.

A phase 1/2, open-label study evaluating twice-daily administration of momelotinib in myelofibrosis.

Momelotinib, a small-molecule inhibitor of Janus kinase 1 and Janus kinase 2, has demonstrated efficacy in myelofibrosis patients with 300 mg, once-daily dosing. This open-label, non-randomized, phase 1/2 study evaluated the safety and therapeutic benefit of momelotinib with twice-daily dosing. A total of 61 subjects with primary myelofibrosis or post-polycythemia vera/post-essential thrombocythemia myelofibrosis with intermediate- or high-risk disease received momelotinib. A phase 1 dose escalation identified 200 mg twice daily as the optimal dose to be expanded in phase 2. The most frequent adverse events were diarrhea (45.9%), peripheral neuropathy (44.3%), thrombocytopenia (39.3%), and dizziness (36.1%), the latter primarily due to a first-dose effect. The response assessment according to the 2006 International Working Group criteria (≥8 weeks duration at any time point) demonstrated spleen response by palpation of 72% (36/50) and anemia response of 45% (18/40). Spleen response by magnetic resonance imaging obtained at 24 weeks was 45.8% (27/59) for all subjects and 54.0% (27/50) for those with palpable splenomegaly at baseline. The symptoms of myelofibrosis were improved in most subjects. Cytokine analysis showed a rapid decline in interleukin-6 with momelotinib treatment, and a slower reduction in other inflammatory cytokines. In the subgroup of subjects with the JAK2V617F mutation at baseline (n=41), momelotinib significantly reduced the allele burden by 21.1% (median) at 24 weeks. These results provide evidence of tolerability and a potential therapeutic activity of momelotinib for subjects that support further evaluation in ongoing, phase 3 randomized trials. (clinicaltrials. gov identifier:01423058).

AT-101 downregulates BCL2 and MCL1 and potentiates the cytotoxic effects of lenalidomide and dexamethasone in preclinical models of multiple myeloma and Waldenström macroglobulinaemia.

Multiple myeloma, the second most common haematological malignancy in the U.S., is currently incurable. Disruption of the intrinsic apoptotic pathway by BCL2 and MCL1 upregulation is observed in >80% of myeloma cases and is associated with an aggressive clinical course. Remarkably, there is no approved drug with the ability to target BCL2 or MCL1. Thus, we investigated the anti-tumour effects of a pan-BCL2 inhibitor, AT-101, which has high binding specificity for BCL2 and MCL1 in preclinical models of plasma cell cancers (Multiple myeloma and Waldenström macroglobulinaemia). Gene expression and immunoblot analysis of six plasma cell cancer models showed upregulation of BCL2 family members. AT-101 was able to downregulate BCL2 and MCL1 in all plasma cell cancer models and induced apoptotic cell death in a caspase-dependent manner by altering mitochondrial membrane permeability. This cytotoxic effect and BCL2 downregulation were further potentiated when AT-101 was combined with lenalidomide/dexamethasone (LDA). NanoString nCounter mRNA quantification and Ingenuity Pathways Analysis revealed differential changes in the CCNA2, FRZB, FYN, IRF1, PTPN11 genes in LDA-treated cells. In summary, we describe for the first time the cellular and molecular events associated with the use of AT-101 in combination with lenalidomide/dexamethasone in preclinical models of plasma cell malignancy.

The investigational agent MLN2238 induces apoptosis and is cytotoxic to CLL cells in vitro, as a single agent and in combination with other drugs.

Chronic lymphocytic leukaemia (CLL) is the most common haematological malignancy in the U.S. The course of the disease has been shown to be negatively impacted by increased levels of BCL2. Strategies to downregulate BCL2 and shift the balance towards cellular demise are actively being explored. Therefore, we examined whether the investigational agent MLN2238 could inhibit the proteasomal machinery and induce CLL cell death while also downregulating BCL2. MLN2238-induced cell death was studied in peripheral blood mononuclear cells from 28 CLL patients. MLN2238 produced a dose-dependent reduction in BCL2 and CLL cell viability with maximum cell death observed at a 50 nmol/l concentration by 48 h. Annexin-V staining, PARP1 and caspase-3 cleavage along with an increase in mitochondrial membrane permeability were noted after cells were treated with MLN2238; however, apoptosis was only partially blocked by the pan-caspase inhibitor z-VAD.fmk. Furthermore, we observed enhanced anti-CLL effects in tumour cells treated with either a combination of MLN2238 and the BH3 mimetic AT-101 or MLN2238 and fludarabine. Together, our data suggest the potential for proteasome inhibitor based therapy in CLL and the rationale design of drug combination strategies based on CLL biology.

Acquired Factor VII Deficiency Associated With Chronic Myeloid Leukemia Blast Crisis.

Factor VII (FVII) is an important, vitamin K-dependent clotting factor. Acquired FVII deficiency is a rare entity that is associated with serious bleeding complications. We report a case of acquired FVII deficiency in a patient with recurrent chronic myeloid leukemia in blast crisis who developed bilateral retinal hemorrhages. The coagulopathy was corrected with the initiation of chemotherapy and subsequent reduction in peripheral blast count.

Real-world experience with ponatinib therapy in chronic phase chronic myeloid leukemia: impact of depth of response on survival and prior exposure to nilotinib on arterial occlusive events.

We surveyed the performance of ponatinib, as salvage therapy, in a real-world setting of chronic phase chronic myeloid leukemia (CML-CP). Among 55 consecutive patients (median age 49 years) with relapsed/refractory CML-CP, 35 (64%) had failed ≥3 tyrosine kinase inhibitors (TKIs), 35 (64%) were pre-treated with nilotinib, and 14 (28%) harbored ABL1T315I. At start of ponatinib (median dose 30 mg/day), 40 patients were already in complete hematologic (CHR), 4 in complete cytogenetic (CCyR), 3 in major molecular (MMR) remission, while 8 had not achieved CHR (NR). Ponatinib improved the depth of response in 13 (33%), 3 (75%), 2 (66%), and 4 (50%) patients with CHR, CCyR, MMR, and NR, respectively (p = 0.02). At a median follow-up of 42 months, 13 (23%) deaths, 5 (9%) blast transformations, and 25 (45%) allogeneic transplants were recorded. Five/10-year post-ponatinib survival was 77%/58% with no significant difference when patients were stratified by allogeneic transplant (p = 0.94), ponatinib-induced deeper response (p = 0.28), or a post-ponatinib ≥CCyR vs CHR remission state (p = 0.25). ABL1T315I was detrimental to survival (p = 0.04) but did not appear to affect response. Prior exposure to nilotinib was associated with higher risk of arterial occlusive events (AOEs; 11% vs 0%; age-adjusted p = 0.04). Ponatinib starting/maintenance dose (45 vs 15 mg/day) did not influence either treatment response or AOEs. Our observations support the use of a lower starting/maintenance dose for ponatinib in relapsed/refractory CML-CP but a survival advantage for deeper responses was not apparent and treatment might not overcome the detrimental impact of ABL1T315I on survival. The association between prior exposure to nilotinib and a higher risk of post-ponatinib AOEs requires further validation.

Resolution of acute pulmonary embolism using anticoagulation therapy alone in coronavirus disease 2019.

OBJECTIVE: To investigate the radiographic resolution of acute pulmonary embolism (PE) using contrast-enhanced computed tomography (CECT) examinations in patients diagnosed with acute PE while hospitalized with coronavirus disease 2019 (COVID-19) and to understand the mid-term and long-term implications of anticoagulation therapy. METHODS: We identified patients with acute PE per CECT and at least one follow-up CECT from March 11, 2020, to May 27, 2021, using a prospective registry of all hospitalized patients with COVID-19 infection receiving care within a multicenter Health System. Initial and follow-up CECT examinations were reviewed independently by two radiologists to evaluate for PE resolution. The Modified Miller Score was used to assess for thrombus burden at diagnosis and on follow-up. RESULTS: Of the 6070 hospitalized patients with COVID-19 infection, 5.7% (348/6070) were diagnosed with acute PE and 13.5% (47/348) had a follow-up CECT examination. The mean ± standard deviation time to follow-up imaging was 44 ± 48 days (range, 3-161 days). Of 47 patients, 47 (72.3%) had radiographic resolution of PE, with a mean time to follow-up of 48 ± 43 days (range, 6-239 days). All patients received anticoagulation monotherapy for a mean of 149 ± 95 days and this included apixaban (63.8%), warfarin (12.8%), and rivaroxaban (8.5%), among others. The mean Modified Miller Score at PE diagnosis and follow-up was 4.8 ± 4.2 (range, 1-14) and 1.4 ± 3.3 (range, 0-16; P < .0001), respectively. Nine patients (19%) died at a mean of 13 ± 8 days after follow-up CECT (range, 1-27 days) and at a mean of 28 ± 16 days after admission (range, 11-68 days). Seen of the nine deaths (78%) deaths were associated with progression of COVID-19 pneumonia. CONCLUSIONS: Hospitalized patients with COVID-19 have a clinically apparent 5.7% rate of developing PE. In patients with follow-up imaging, 72.3% had radiographic thrombus resolution at a mean of 44 days while on anticoagulation. Prospective studies of the natural history of PEs with COVID-19 that include systematic follow-up imaging are warranted to help guide anticoagulation recommendations.

Hemophagocytic Lymphohistiocytosis for the Internist and Other Primary Care Providers.

Hemophagocytic lymphohistiocytosis (HLH) syndrome is a hyperinflammatory state that leads to life-threatening, disproportionate activation of the immune system and may be confused for and concomitantly exist with sepsis. However, its treatment differs from sepsis, requiring early initiation of immunosuppressive treatment. While HLH syndrome is more commonly diagnosed in children, internists and other primary care providers must be familiar with the diagnosis and treatment of adult patients with HLH in the hospital and outpatient setting. In this article, we review the essentials that an internist and other primary care providers managing adult HLH patients should know.

Deep vein thrombosis in the setting of Klippel-Trenaunay syndrome and sirolimus treatment.

Klippel-Trenaunay syndrome (KTS) is a congenital vascular disorder characterized by the triad of cutaneous capillary malformation, lymphatic and venous anomalies, and soft tissue and bone overgrowth. Sirolimus is a mechanistic target of rapamycin inhibitor used as an immunosuppressive drug. It has also been used to improve and treat vascular malformations that can predispose to intravascular coagulopathy. We have described the case of a patient with KTS receiving a therapeutic anticoagulation dose, for whom sirolimus was initiated, and who had presented with an extensive venous thromboembolism. Correlations between the use of sirolimus in patients with KTS are limited, and cautious use and monitoring could be necessary.

V.I.T.A.M. in COVID 19: A Systematic Approach to a Global Pandemic.

INTRODUCTION: In the unprecedented era of COVID-19, ongoing research and evolution of evidence has led to ever-changing guidelines for clinical monitoring and therapeutic options. Formulating treatment protocols requires the understanding and application of the evolving research. OBJECTIVE: The primary objective of this study is to present a systematic evidence-based approach to synthesize the necessary data in order to optimize the management of COVID-19. METHODS: At Mayo Clinic Florida, we developed a multidisciplinary centralized COVID Treatment Review Panel (TRP) of expert pulmonologists, intensivists, infectious disease specialists, anesthesiologists, hematologists, rheumatologists, and hospitalists that in real-time reviews the latest evidence in peer-reviewed journals, the available clinical trials, and help guide the rapid application of therapeutics or interventions to the patient and the bedside provider. RESULTS/CONCLUSIONS: The multi-disciplinary team approach of synthesizing clinical data and coordinating care is effective in responding to rapidly evolving and changing evidence. Systematic data collection and evidence-based treatment algorithms enable physicians to rapidly translate the current literature to clinical practice, and improve care and outcomes of patients.

Deep vein thrombosis and pulmonary embolism among hospitalized coronavirus disease 2019-positive patients predicted for higher mortality and prolonged intensive care unit and hospital stays in a multisite healthcare system.

OBJECTIVE: We assessed the incidence of deep vein thrombosis (DVT) and pulmonary embolism (PE) in hospitalized patients with coronavirus disease 2019 (COVID-19) compared with that in a matched cohort with similar cardiovascular risk factors and the effects of DVT and PE on the hospital course. METHODS: We performed a retrospective review of prospectively collected data from COVID-19 patients who had been hospitalized from March 11, 2020 to September 4, 2020. The patients were randomly matched in a 1:1 ratio by age, sex, hospital of admission, smoking history, diabetes mellitus, and coronary artery disease with a cohort of patients without COVID-19. The primary end point was the incidence of DVT/PE and the odds of developing DVT/PE using a conditional logistic regression model. The secondary end point was the hospitalization outcomes for COVID-19 patients with and without DVT/PE, including mortality, intensive care unit (ICU) admission, ICU stay, and length of hospitalization (LOH). Multivariable regression analysis was performed to identify the variables associated with mortality, ICU admission, discharge disposition, ICU duration, and LOH. RESULTS: A total of 13,310 patients had tested positive for COVID-19, 915 of whom (6.9%) had been hospitalized across our multisite health care system. The mean age of the hospitalized patients was 60.8 ± 17.0 years, and 396 (43.3%) were women. Of the 915 patients, 82 (9.0%) had had a diagnosis of DVT/PE confirmed by ultrasound examination of the extremities and/or computed tomography angiography of the chest. The odds of presenting with DVT/PE in the setting of COVID-19 infection was greater than that without COVID-19 infection (0.6% [5 of 915] vs 9.0% [82 of 915]; odds ratio [OR], 18; 95% confidence interval [CI], 8.0-51.2; P < .001). The vascular risk factors were not different between the COVID-19 patients with and without DVT/PE. Mortality (P = .02), the need for ICU stay (P < .001), duration of ICU stay (P < .001), and LOH (P < .001) were greater in the DVT/PE cohort than in the cohort without DVT/PE. On multivariable logistic regression analysis, the hemoglobin (OR, 0.71; 95% CI, 0.46-0.95; P = .04) and D-dimer (OR, 1.0; 95% CI, 0.33-1.56; P = .03) levels were associated with higher mortality. Higher activated partial thromboplastin times (OR, 1.1; 95% CI, 1.00-1.12; P = .03) and higher interleukin-6 (IL-6) levels (OR, 1.0; 95% CI, 1.01-1.07; P = .05) were associated with a greater risk of ICU admission. IL-6 (OR, 1.0; 95% CI, 1.00-1.02; P = .05) was associated with a greater risk of rehabilitation placement after discharge. On multivariable gamma regression analysis, hemoglobin (coefficient, -3.0; 95% CI, 0.03-0.08; P = .005) was associated with a prolonged ICU stay, and the activated partial thromboplastin time (coefficient, 2.0; 95% CI, 0.003-0.006; P = .05), international normalized ratio (coefficient, -3.2; 95% CI, 0.06-0.19; P = .002) and IL-6 (coefficient, 2.4; 95% CI, 0.0011-0.0027; P = .02) were associated with a prolonged LOH. CONCLUSIONS: A significantly greater incidence of DVT/PE occurred in hospitalized COVID-19-positive patients compared with a non-COVID-19 cohort matched for cardiovascular risk factors. Patients affected by DVT/PE were more likely to experience greater mortality, to require ICU admission, and experience prolonged ICU stays and LOH compared with COVID-19-positive patients without DVT/PE. Advancements in DVT/PE prevention are needed for patients hospitalized for COVID-19 infection.

Racial/ethnic differences in patients with anemia and folate deficiency.

OBJECTIVE: To determine the presence of racial/ethnic differences in patients with anemia and serum folate deficiency. METHODS: We performed a retrospective analysis of data from patient samples collected from January 2010 to October 2018. Reference laboratory ranges were determined by Mayo Clinic Reference Laboratories. Race and ethnicity were classified according to National Institutes of Health categories. RESULTS: The analysis comprised 197 974 samples. Hemoglobin, hematocrit, and SF results were available for 173 337, 173 056, and 129 760 samples, respectively. Of the samples, 46 505 (26.8%) showed anemia, with a higher prevalence among American Indian/Alaskan Natives (AI/AN) 42.9% and African Americans (AA) 47.2% (P < .001). SF deficiency was present in 897 (0.7%), with a higher prevalence among AI/AN (9, [1.4%]) and AA (78, [1.2%]) and a lower prevalence in non-Hispanic whites (NHW) (758, [0.7%]), Hispanics (40, [0.6%]), and Asians (8, [0.3%]). In multivariable analysis, the prevalence of anemia was higher in all non-NHW racial/ethnic groups: AA (OR, 3.67, [95%CI: 3.47-3.88, P < .001]), AI/AN (OR, 3.25, [95%CI: 2.71-3.90, P < .001]), Asians (OR, 1.62, [95%CI: 1.47-1.77, P < .001]), and Hispanics (OR, 1.41, [95%CI: 1.32-1.50, P < .001]). SF deficiency was more common in AA (OR, 1.48, [95%CI: 1.17-1.88, P.001]) and less common in Asians (OR, 0.35, [95%CI: 0.17-0.70, P = .003]), compared with NHW. CONCLUSIONS: We showed significant racial/ethnic differences in anemia and SF deficiency. Differences were observed especially among NHW, AA, and Asians. We believe that these differences may be explained by social determinants of health. More research is needed regarding the causes of these differences and their clinical implications at a population level.

ACVR1/JAK1/JAK2 inhibitor momelotinib reverses transfusion dependency and suppresses hepcidin in myelofibrosis phase 2 trial.

Momelotinib (MMB) is a JAK1/2 and ACVR1 inhibitor with demonstrated clinical activity in all 3 hallmarks of myelofibrosis (MF): anemia, constitutional symptoms, and splenomegaly. In this phase 2 open-label translational biology study (NCT02515630) of 41 transfusion-dependent patients with MF, we explored mechanisms underlying the favorable activity of MMB on MF-associated iron-restricted anemia, including its impact on serum hepcidin levels, and markers of iron storage and availability, erythropoiesis, and inflammation. A transfusion-independent response (TI-R), defined as red blood cell transfusion independence (TI) ≥12 weeks at any time on study, occurred in 17 patients (41%; 95% confidence interval [CI], 26%-58%), including 14 patients (34%; 95% CI, 20%-51%) who achieved TI-R by week 24. In addition, 78% of TI nonresponse (TI-NR) patients achieved a ≥50% decrease in transfusion requirement for ≥8 weeks. Adverse events (AEs) were consistent with previous studies of MMB in MF, with cough, diarrhea, and nausea as the most common. Twenty-one patients experienced grade ≥3 AEs, most commonly anemia and neutropenia. Consistent with preclinical data, daily MMB treatment led to an acute and persistent decrease in blood hepcidin associated with increased iron availability and markers of erythropoiesis. Baseline characteristics associated with TI-R were lower inflammation and hepcidin as well as increased markers of erythropoiesis and bone marrow function. Overall, the study demonstrates that MMB treatment decreases hepcidin in conjunction with improving iron metabolism and erythropoiesis, suggesting a mechanistic explanation for the reduced transfusion dependency observed in transfusion-dependent MF patients treated with MMB, thereby addressing the key unmet medical need in the MF population.

Anticoagulation in COVID-19: A Systematic Review, Meta-analysis, and Rapid Guidance From Mayo Clinic.

A higher risk of thrombosis has been described as a prominent feature of coronavirus disease 2019 (COVID-19). This systematic review synthesizes current data on thrombosis risk, prognostic implications, and anticoagulation effects in COVID-19. We included 37 studies from 4070 unique citations. Meta-analysis was performed when feasible. Coagulopathy and thrombotic events were frequent among patients with COVID-19 and further increased in those with more severe forms of the disease. We also present guidance on the prevention and management of thrombosis from a multidisciplinary panel of specialists from Mayo Clinic. The current certainty of evidence is generally very low and continues to evolve.

Clinical outcomes of adults with hemophagocytic lymphohistiocytosis treated with the HLH-04 protocol: a retrospective analysis.

Hemophagocytic lymphohistiocytosis (HLH) is a rare syndrome of pathologic immune activation in children that is increasingly being recognized in adults. Efficacy data for the HLH-04 protocol in adults is lacking. This study retrospectively analyzed 31 adult patients, median age 46 years, who received HLH-04 from 1/1/2004 to 5/1/2018. HLH etiology included malignancy (n = 9), autoimmune (n = 8), infection (n = 8), and idiopathic (n = 6). Eighteen patients were evaluable for response at week 4 with 7 having no response, 11 reaching partial response, and 0 reaching complete response (CR). Six patients eventually achieved CR at a median 195 days. The 1-year overall survival (OS) was 35% and median OS was 3.2 months. Univariate analysis showed shorter survival for hemoglobin <9 g/dL (HR 4.29, p = 0.003), platelets <100 × 109/L (HR 4.06, p = 0.027), ANC <1 × 109/L (HR 5.24, p = 0.001), and total bilirubin >1.2 mg/dL (HR 3.30, p = 0.022). Outcomes of adults treated with HLH-04 remain dismal and newer treatment modalities are needed.

Sequence of Splenectomy and Rituximab for the Treatment of Steroid-Refractory Immune Thrombocytopenia: Does It Matter?

OBJECTIVE: To evaluate the impact of the sequence of treatment with rituximab and/or splenectomy on time to relapse for patients with steroid-refractory immune thrombocytopenia (ITP). PATIENTS AND METHODS: Patients 18 years or older with steroid-refractory immune thrombocytopenia who underwent treatment with splenectomy or rituximab from January 1, 2002, through December 31, 2015, at Mayo Clinic. Evaluation included freedom from relapse (FFR) and response rates after treatment with rituximab or splenectomy as single or sequential interventions. RESULTS: A total of 218 eligible patients with ITP who were treated according to standard of care were included in this analysis. Patients failing steroids treated with splenectomy had a higher 5-year FFR than did those treated with rituximab (67.4% vs 19.2%; P<.001, propensity-score matched). Patients who failed splenectomy and were then treated with rituximab had a 2-year FFR similar to that of patients who failed rituximab and were then treated with splenectomy (73.4% vs 59.9%; P=.52). Patients treated with rituximab after splenectomy had a longer 2-year FFR than did patients treated with rituximab as a second-line treatment (73.4% vs 29.0%; P<.001). CONCLUSION: For patients with ITP that relapse after treatment with steroids, splenectomy provides longer FFR than rituximab as a second-line therapy. Among patients who fail second-line treatment with splenectomy or rituximab, those who end up receiving sequential splenectomy-rituximab or rituximab-splenectomy therapy seem to derive similar benefit in the long term. Patients who received rituximab after splenectomy seem to derive superior benefit than do those who are treated with rituximab with an intact spleen.

Post-transplant erythrocytosis refractory to ACE inhibitors and angiotensin receptor blockers.

Post-transplant erythrocytosis (PTE) is a condition with elevated haematocrit (hct) in renal allograft recipients. The mainstay of treatment is ACE inhibitors (ACEi) or angiotensin II receptor blockers (ARB), but seldom phlebotomy. PTE must be recognised early to prevent major thromboembolic events. We present a case of PTE that was refractory to blockade of renin-angiotensin system (RAS) by ACEi and ARB and required phlebotomy for control of hct. Our review of medical literature about prevalence and pathophysiology of PTE suggests that approximately 22% of patients with PTE are refractory to ACEi/ARB treatment. There are four plausible pathways that appear to play a role in causing PTE: disruption of erythropoietin regulation, mitogenic effect of the RAS on erythroid lineage, insulin-like growth factor 1 and androgenic stimulation. Presently, there is no unifying hypothesis involving these factors, but refractoriness to ACEi/ARB may represent a distinct subcategory of PTE.