Citations

Hereditary erythrocytosis is associated with high oxygen affinity hemoglobin variants (HOAs), 2,3‐bisphosphoglycerate deficiency and abnormalities in EPOR and the oxygen‐sensing pathway proteins PHD, HIF2α, and VHL. Our laboratory has 40 years of experience with hemoglobin disorder testing and we have characterized HOAs using varied protein and molecular techniques including functional assessment by p50 analysis. In addition, we have more recently commenced adding the assessment of clinically relevant regions of the VHL , BPGM, EPOR , EGLN1 (PHD2), and EPAS1 (HIF2A) genes in a more comprehensive hereditary erythrocytosis panel of tests. Review of our experience confirms a wide spectrum of alterations associated with erythrocytosis which we have correlated with phenotypic and clinical features. Through generic hemoglobinopathy testing, we have identified 762 patients with 81 distinct HOA Hb variants (61 β, 20 α), including 12 that were first identified by our laboratory. Of the 1192 cases received for an evaluation specific for hereditary erythrocytosis, approximately 12% had reportable alterations: 85 pathogenic/likely pathogenic mutations and 58 variants of unknown significance. Many have not been previously reported. Correlation with clinical and phenotypic data supports an algorithmic approach to guide economical evaluation; although, testing is expanded if the suspected causes are negative or of uncertain significance. Clinical features are similar and range from asymptomatic to recurrent headaches, fatigue, restless legs, chest pain, exertional dyspnea and thrombotic episodes. Many patients were chronically phlebotomized with reported relief of symptoms.

Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is a low-grade B-cell neoplasm and ∼2% to 9% patients develop an aggressive lymphoma, most commonly diffuse large B-cell lymphoma (Richter transformation, DLBCL-RT). Programmed death-1 (PD-1) pathway plays a crucial role in tumor host immunity evasion and its blockade has emerged as an effective anti-cancer immunotherapy. PD-L1 and PD-1 expression has shown predictive value in anti-PD cancer immunotherapy; however, it has not been well documented in CLL/SLL and DLBCL-RT. We evaluated PD-1 and PD-L1 expression by immunohistochemistry in 39 CLL/SLL, 15 DLBCL-RT, and 26 other DLBCL. In CLL/SLL, neoplastic B-cell PD-1 expression was weak and restricted to prolymphocytes/paraimmunoblasts within proliferation centers (PCs) and accentuated PCs of all sizes. Neoplastic B-cell PD-1 expression was highly prevalent and demonstrated increased intensity in DLBCL-RT, but in contrast was only rarely seen in other DLBCL (12/15 vs. 1/26; P<0.0001). An excellent correlation (90% concordance) was observed between neoplastic B-cell PD-1 immunohistochemistry positivity and molecularly defined CLL/SLL clonal relatedness in DLBCL-RT. PD-L1 expression was observed on the neoplastic B cells in rare DLBCL-RT and other DLBCL cases (1/15 vs. 1/26; P>0.05) as well as background histiocytes and dendritic cells. Overall survival of DLBCL-RT was significantly inferior to that of the other DLBCL (median, 16.9 vs. 106.1 mo; P=0.002). Our findings suggest a biological continuum from prolymphocytes/paraimmunoblasts in CLL/SLL PCs to the neoplastic B-cells in DLBCL-RT. The characteristic PD-1 expression in DLBCL-RT makes it a potential surrogate marker for determining clonal relatedness to CLL/SLL, which may have important prognostic and therapeutic implications.

AbstractWaldenström macroglobulinemia (WM) is an immunoglobulin M‐associated lymphoma, with majority of cases demonstrating MYD88 locus alteration, most commonly, MYD88L265P. Owing to low prevalence of the wild‐type (WT) MYD88 genotype in WM, clinically relevant data in this patient population are sparse, with one study showing nearly a 10‐fold increased risk of mortality in this subgroup compared to patients with MYD88L265P mutation. We studied a large cohort of patients with MYD88L265P and MYD88WT WM, evaluated at Mayo Clinic, Rochester, between 1995 and 2016, to specifically assess the impact of these genotypes on clinical course. Of 557 patients, MYD88L265P mutation status, as determined by allele‐specific polymerase chain reaction, was known in 219, and 174 (79%) of those exhibited MYD88L265P, 157 of 174 patients had active disease. Of 45 (21%) patients with MYD88WT genotype, 44 had active disease. The estimated median follow‐up was 7.0 years; median overall survival was 10.2 years (95% CI: 8.4‐16.5) for MYD88L265P versus 13.9 years (95% CI: 6.4‐29.3) for the MYD88WT (P = 0.86). The time‐to‐next therapy from frontline treatment and the presenting features were similar in the two patient populations. For patients with smoldering WM at diagnosis, the median time‐to‐progression to active disease was 2.8 years (95% CI: 2.2‐3.8) in the MYD88L265P cohort and 1.9 years (95% CI: 0.7‐3.1) in the MYD88WT cohort (P = 0.21). The frequency of transformation to high‐grade lymphoma, or the development of therapy‐elated myelodysplastic syndrome was higher in the MYD88WT cohort (16% versus 4% in the MYD88L265P, P = 0.009). In conclusion, MYD88L265P mutation does not appear to be a determinant of outcome, and its presence may not be a disease‐defining feature in WM. Our findings warrant external validation, preferably through prospective studies.

Key Points Pembrolizumab was first shown to be clinically active in CLL patients with RT. PD-1 and PD-L1 expression in tumor microenvironment are promising biomarkers to select RT patients for PD-1 blockade.

Abstract Objectives: Flow cytometry immunophenotyping has been suggested as an adjunctive technique in the evaluation of myeloid malignancies, especially in the myelodysplastic syndromes. However, its use has been limited due to complexity and cost restraints. The goal of this study is to attempt a simpler approach to flow cytometry immunophenotyping in myeloid neoplasms. Methods: We analyzed bone marrow specimens of 45 selected patients and an additional 99 consecutive random patients using a limited antibody panel. Results: Normal CD34-positive blasts show a characteristic pattern of CD13/HLA-DR expression, with three readily identifiable subpopulations. In contrast, myeloid neoplasms frequently show loss of this heterogeneity. Conclusions: Analysis of a limited antibody panel with a focus on CD13/HLA-DR expression provides relatively high specificity and sensitivity for the detection of myeloid neoplasms.

Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) patients with purine analog refractory disease or TP53 dysfunction still have limited treatment options and poor survival. Alemtuzumab‐containing chemoimmunotherapy regimens can be effective but frequently cause serious infections. We report a Phase II trial testing the efficacy and tolerability of a short‐duration regimen combining pentostatin, alemtuzumab, and low‐dose high‐frequency rituximab designed to decrease the risk of treatment‐associated infections and to limit the loss of CD20 expression by CLL cells. The study enrolled 39 patients with progressive CLL that was either relapsed/refractory (n = 36) or previously untreated with 17p13 deletion (17p13−) (n = 3). Thirteen (33%) patients had both 17p13− and TP53 mutations predicted to be dysfunctional, and eight patients had purine analog refractory CLL without TP53 dysfunction. Twenty‐six (67%) patients completed therapy, with only five (13%) patients having treatment‐limiting toxicity and no treatment‐related deaths. Twenty‐two (56%) patients responded to treatment, with 11 (28%) complete responses (four with incomplete bone marrow recovery). Median progression‐free survival was 7.2 months, time to next treatment was 9.1 months, and overall survival was 34.1 months. The majority of deaths (82%) were caused by progressive disease, including transformed diffuse large B‐cell lymphoma (n = 6). Correlative studies showed that low‐dose rituximab activates complement and natural killer cells without a profound and sustained decrease in expression of CD20 by circulating CLL cells. We conclude that pentostatin, alemtuzumab, and low‐dose high‐frequency rituximab is a tolerable and effective therapy for CLL and that low‐dose rituximab therapy can activate innate immune cytotoxic mechanisms without substantially decreasing CD20 expression. Am. J. Hematol. 89:757–765, 2014. © 2014 Wiley Periodicals, Inc.