Measurable Residual Disease Monitoring in Lymphoma

PURPOSE OF REVIEW

The utility of analyzing circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), and disease in the bone marrow as an adjunctive tool in caring for hematologic cancer patients is expanding. This holds true for lymphoma where these biomarkers are being explored as a means of genotyping and quantifying disease. Regarding the latter, they can be used to monitor measurable residual disease (MRD) during and after treatment. This holds potential for aiding clinical decisions amidst treatment, detecting earlier relapse, and improving prognostication. Here, we review the evidence to support these applications in a variety of lymphoma subtypes.

RECENT FINDINGS

Numerous clinical trials across a variety of lymphomas have demonstrated value in MRD monitoring. MRD monitoring is often prognostic for progression free survival (PFS) and even overall survival (OS) at several time points in a disease course, particularly when utilizing serial measurements. With regards to tailoring treatment, there are a growing number of trials examining MRD-adaptive treatment strategies to intensify or de-escalate treatment to individualize care. Lastly, MRD monitoring has been utilized successfully in detecting earlier relapse when compared to more standard methods of clinical surveillance such as radiographic assessment. Although not routinely implemented into clinical practice, MRD monitoring in lymphoma is helping shape the future landscape of this disease by aiding in prognostication, guiding therapy, and detecting earlier relapse. Steps to standardize and further examine this technology prospectively are being taken to bring MRD monitoring to the forefront of the field.

Managing toxicities of Bruton tyrosine kinase inhibitors

Inhibition of Bruton's tyrosine kinase (BTK) has revolutionized the treatment landscape for patients with chronic lymphocytic leukemia (CLL). By targeting this critical kinase in proximal B-cell receptor signaling, BTK inhibitors (BTKis) impair cell proliferation, migration, and activation of NF-κB. Clinically, because indefinite inhibition is a mainstay of therapy, there is an extended period of exposure in which adverse effects can develop. Given the impressive efficacy and activity of BTKis in the treatment of patients with CLL, appropriate management of treatment-emergent adverse events (AEs) is of paramount importance. Here we review the BTKi landscape and present the available toxicity and safety data for each agent. The long-term toxicity profile of ibrutinib, a first-in-class inhibitor, is well characterized and includes a clinically significant incidence of cardiac arrhythmias, bleeding, infection, diarrhea, arthralgias, and hypertension. Acalabrutinib, the initial second-generation BTKi to earn approval from the US Food and Drug Administration, demonstrates improved kinase selectivity for BTK, with commonly observed adverse reactions including infection, headache, and diarrhea. Mediated by both on-target inhibition of BTK and variable off-target inhibition of other kinases including interleukin-2-inducible T-cell kinase (ITK), tyrosine-protein kinase (TEC), and endothelial growth factor receptor (EGFR), the toxicity profile of BTKis is closely linked to their pattern of kinase binding. Other emerging BTKis include second-generation agents with variable degrees of kinase selectivity and third-generation agents that exhibit reversible noncovalent binding to BTK. We also highlight critical considerations for the prevention and monitoring of AEs and offer practical management strategies for treatment-emergent toxicities.

Effects of the Bruton’s tyrosine kinase inhibitor ibrutinib on humoral immunity in patients with chronic lymphocytic leukemia (HUM1P.258)

Chronic lymphocytic leukemia (CLL) is characterized by immune dysregulation, often including hypogammaglobulinemia. Ibrutinib, a covalent inhibitor of Bruton’s tyrosine kinase (BTK), is highly active in B cell malignancies, including CLL. Inactivating mutations in BTK cause X-linked agammaglobulinemia. We evaluated the impact of ibrutinib on immunoglobulin (Ig) levels in CLL patients (pts) treated at NIH. Consistent with previous reports, IgG remained stable during the first 6 months, but decreased from a median of 707 mg/dL at baseline to 611 mg/dL at 24 months (17% reduction, n=25, p<0.0001). In contrast, there was a sustained increase in IgA and a transient increase in IgM. Next, we assessed serum free light chains (FLCs) to distinguish the effects on clonal from non-clonal B cells. In κ-clonal CLL cases, the clonal (κ) FLC decreased from a median of 6.71 to 1.42 mg/dL after 6 months (n=39, p<0.0001). Interestingly, the non-clonal (λ) FLC increased, suggesting the recovery of normal B cell function. Consistently, we found an increase in normal B cells in blood and bone marrow, including early B cell precursors. In comparison, CLL pts (n=16) treated with anti-CD20-based chemoimmunotherapy also showed a decrease in IgG at 24 months (12% reduction, p=0.0052), and surprisingly, an improvement in IgA levels, suggesting that the latter effect is not drug-specific but due to tumor reduction. The consequences of long-term BTK inhibition on immune function require further study.

Risk Factors for Catheter Associated Urinary Tract Infections in a Pediatric Institution

PURPOSE

Catheter associated urinary tract infections are an essential measure for health care quality improvement that affects reimbursement through hospital acquired condition reduction programs in adult patients. With the mounting importance of preventing such infections we evaluated risk factors for acquiring catheter associated urinary tract infections in pediatric patients.

MATERIALS AND METHODS

All catheter associated urinary tract infections were identified at 1 pediatric institution from September 2010 to August 2014 from a prospective database maintained by the infection control office. To identify risk factors patients with a catheter associated urinary tract infection were individually matched to control patients with a urinary catheter but without infection by age, gender, date and the hospital location of the infection in 1:2 fashion.

RESULTS

A total of 50 patients with catheter associated urinary tract infection were identified and matched to 100 control patients. Compared to controls the patients with infection were more likely to have a catheter in place for longer (2.9 days, OR 1.08, 95% CI 1.01, 1.15, p = 0.02). They were also more likely to be on contact precautions (OR 4.00, 95% CI 1.73, 9.26, p = 0.001), and have concurrent infections (OR 3.04, 95% CI 1.39, 6.28, p = 0.005) and a history of catheterization (OR 3.24, 95% CI 1.55, 6.77, p = 0.002). Using a conditional multivariate regression model the 3 most predictive variables were duration of catheter drainage, contact isolation status and history of catheterization.

CONCLUSIONS

Longer duration of urinary catheter drainage, positive contact precautions status and a history of catheterization appear to be associated with a higher risk of catheter associated urinary tract infection in hospitalized pediatric patients. Physicians should attempt to decrease the duration of catheterization, especially in patients who meet these criteria, to minimize the risk of catheter associated urinary tract infection.

Ibrutinib-induced lymphocytosis in patients with chronic lymphocytic leukemia: correlative analyses from a phase II study

Ibrutinib and other targeted inhibitors of B-cell receptor signaling achieve impressive clinical results for patients with chronic lymphocytic leukemia (CLL). A treatment-induced rise in absolute lymphocyte count (ALC) has emerged as a class effect of kinase inhibitors in CLL and warrants further investigation. We here report correlative studies in 64 patients with CLL treated with ibrutinib. We quantified tumor burden in blood, lymph nodes, spleen, and bone marrow, assessed phenotypic changes of circulating cells, and measured whole blood viscosity. With just one dose of ibrutinib the average increase in ALC was 66%, and in over 40% of patients the ALC peaked within 24 hours of initiating treatment. Circulating CLL cells on day 2 showed increased Ki67 and CD38 expression, indicating an efflux of tumor cells from the tissue compartments into the blood. The kinetics and degree of the treatment-induced lymphocytosis was highly variable; interestingly in patients with a high baseline ALC the relative increase was mild and resolution rapid. After two cycles of treatment the disease burden in lymph node, bone marrow, and spleen decreased irrespective of the relative change in ALC. Whole blood viscosity was dependent on both ALC and hemoglobin. No adverse events were attributed to the lymphocytosis.

Biology of chronic lymphocytic leukemia in different microenvironments: clinical and therapeutic implications

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of mature monoclonal B cells in peripheral blood, bone marrow, spleen, and lymph nodes. The trafficking, survival, and proliferation of CLL cells is tightly regulated by the surrounding tissue microenvironment and is mediated by antigenic stimulation, close interaction with various accessory cells and exposure to different cytokines, chemokines, and extracellular matrix components. In the last decade there have been major advances in the understanding of the reciprocal interactions between CLL cells and the various microenvironmental compartments. This article discusses the role of the microenvironment in the context of efforts to develop novel therapeutics that target the biology of CLL.

Abstract LB-141: Potent single agent activity of Ibrutinib (PCI-32765) in patients with chronic lymphocytic leukemia (CLL): clinical and translational results from an ongoing phase II study

Background: B-cell receptor (BCR) activation plays a pivotal role in the pathogenesis and for progression of CLL. Ibrutinib (PCI-32765), an irreversible inhibitor of Bruton's tyrosine kinase (BTK), can disrupt BCR signaling and has durable antitumor activity in CLL. We initiated a phase II single center trial to extend this experience and assess the impact of ibrutinib on tumor cells in vivo. Methods: Treatment naïve (TN) and relapsed/refractory (R/R) pts with CLL are treated with 420 mg ibrutinib daily. Pts are enrolled in 2 cohorts: 1) deletion (del) of chromosome 17p and 2) >65yo and treated until disease progression. Response is evaluated at 6 months (mo) and every 6 mo thereafter. 17p del was assessed by FISH cytogenetics. Spleen volume on computed tomography (CT) scans was computed using a General Electric Advanced Workstation Server. Results: With a median follow-up of 9 mo we report on the first 53 patients: for del 17p n=29; 15 TN, 14 R/R; and for >65yo n=24; 8 TN, 16 R/R. Estimated event free survival at 12 mo is 94%. Most adverse events were mild with non hematologic toxicities (regardless of causality) grade ≥3 in <13% of pts. Two deaths on study were not treatment related. At 6 mo 95% of pts (n=44 evaluable) had a nodal response (median reduction in lymph node size of 73%) and 52% of pts had a partial response (PR) by IWCLL criteria. One pt had progressive disease (presumed Richter's transformation). All pts had a decrease in splenomegaly. The median reduction of splenic volume computed from CTs was 55% (30-1716 ml). Tumor infiltration in bone marrow biopsies (n=26), decreased by a median 82% as assessed by immunohistochemistry for CD79a and the median ALC decreased from 79 k/µl (0.5-402) to 32 k/µl (0.8-167) at 6 mo for a median reduction of 62%. We evaluated the in vivo effects of ibrutinib using blood and tissue samples collected pre and during ibrutinib treatment. On treatment expression of genes known to be induced by B-cell receptor (BCR) activation (Herishanu et al 2011) was significantly reduced in CLL cells in the peripheral blood (PB) in all pts (n=15; median reduction 57%; P<.001). Consistent with inhibition of BCR signaling, we found concurrent reduction in PLCγ2 phosphorylation; a direct target of BTK. Patients also donated matched lymph node (LN) core biopsies pre-treatment and within the first 4 days on treatment. Ibrutinib inhibited BCR signaling in the LN (n=8, P=.004) to a similar degree as observed in the PB. Similarly, ibrutinib decreased expression of NF-κB target genes in PB and LN. In keeping with inhibition of BCR and NF-κB signaling surface markers of cellular activation such as CD38, CD69, and CD86 were significantly reduced by ibrutinib as measured by flow cytometry (P<.02). Finally, ibrutinib significantly reduced tumor proliferation as determined by the percentage of PB CLL cells expressing Ki67 (median reduction of 80%; P<.001). Conclusions: Ibrutinib as a single agent is well tolerated and highly effective in both TN and R/R pts achieving rapid disease control in blood, lymph nodes, spleen and bone marrow that is durable. Correlative studies on patient samples during ibrutinib treatment provide direct evidence for on target effects of ibrutinib in vivo demonstrating effective and sustained inhibition of BCR and NF-κB signaling in both PB and LNs. Ibrutinib deserves further investigation as targeted therapy for CLL.

We thank our patients for participation and donation of blood and tissue samples. Supported by the Intramural Research Program of NIH.

Citation Format: Adrian Wiestner, Sarah Herman, Rashida Mustafa, Janet Valdez, Jade Jones, Nakhle Saba, Andrew Lipsky, Diane C. Arthur, Gerald Marti, Francine Thomas, Irina Maric, Stefania Pittaluga, Xin Tian, Susan Soto, Georg Aue, Mohammed Z. Farooqui. Potent single agent activity of Ibrutinib (PCI-32765) in patients with chronic lymphocytic leukemia (CLL): clinical and translational results from an ongoing phase II study. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-141. doi:10.1158/1538-7445.AM2013-LB-141

Asymptomatic enlargement of the clavicle: a review of underlying aetiologies

An asymptomatic enlargement of the medial clavicle is a condition that is often both missed and misdiagnosed. We review the most common causes of an isolated and asymptomatic enlargement of the medial clavicle. Underlying aetiologies include osteoarthritis of the sternoclavicular joint, condensing osteitis, spontaneous dislocation of the sternoclavicular joint, and sternocostoclavicular hyperostosis. Key points in the history and physical examination as well as characteristic radiographic findings are sufficient for correct diagnoses. Treatment is conservative.

Combining flow cytometry and gfp reporter gene for quantitative evaluation of Pectpbacterium carotovorum ssp. carotovorum in Ornithogalum dubium plantlets

AIMS

Ornithogalum dubium is a natural host of the soft rot pathogen Pectobacterium carotovorum ssp. carotovorum (Pcc). The present study was aimed to develop a quantification system for Pcc expressing a gfp reporter gene, using fluorescent activated cell sorter (FACS) in planta.

METHODS AND RESULTS

Several calibration steps were required to distinctly gate the GFP-labelled bacteria at FL1 mode and count the bacteria. To validate the bacterial counts obtained by FACS analysis, an internal standard of polystyrene green fluorescent microsphere beads was employed, resulting in high correlation with serial dilutions and plate counting. This allowed quantification of the bacteria, with no further need to culture, dilute or plate the cells. Micropropagation tools were developed to produce uniform plantlets of O. dubium, which were either inoculated with increasing concentrations of Pcc or elicited for resistance towards Pcc using methyl jasmonate. The rapid counting procedure allowed recovering, gating and counting the bacterial population in planta, separately from the plant cells background and from the microsphere beads.

CONCLUSIONS

The FACS based quantification approach of Pcc was found accurate, reproducible and time saving, thus useful for counting bacteria in planta.

SIGNIFICANCE AND IMPACT OF THE STUDY

The combination of time- and cost-saving approach for Pcc quantification with efficient screening tools during early stages of micropropagation may facilitate the preliminary process of selection for resistant cultivars.

Association between fighting behavior and catecholamine biosynthetic enzyme activity in two inbred mouse sublines

Levels of three adrenal catecholamine synthesizing enzymes and isolation-induced fighting behavior were studied in two related sublines of the Balb/c inbred mouse strain. Enzyme levels were twice as high in the adrenals of Balb/cJ mice as in those of the Balb/cN mice; heterozygous progeny were intermediate between their parents in the levels of the three enzymes. These sublines also showed marked differences in their fighting behavior after a 2-week isolation period. Balb/cJ mice fought immediately after presentation of an intruder mouse, while Balb/cN mice did not fight at any time during the test. Heterozygous progeny behaved more like the Balb/cN (non-fighters). Analysis of F(2) mice suggested that the differences in fighting behavior were determined by a single gene, with fighting being recessive.