Sung W. Choi

ST2 as a Marker for Risk of Therapy-Resistant Graft-versus-Host Disease and Death

BACKGROUNDnNo plasma biomarkers are associated with the response of acute graft-versus-host disease (GVHD) to therapy after allogeneic hematopoietic stem-cell transplantation.nnnMETHODSnWe compared 12 biomarkers in plasma obtained a median of 16 days after therapy initiation from 10 patients with a complete response by day 28 after therapy initiation and in plasma obtained from 10 patients with progressive GVHD during therapy. The lead biomarker, suppression of tumorigenicity 2 (ST2), was measured at the beginning of treatment for GVHD in plasma from 381 patients and during the first month after transplantation in three independent sets totaling 673 patients to determine the association of this biomarker with treatment-resistant GVHD and 6-month mortality after treatment or transplantation.nnnRESULTSnOf the 12 markers, ST2 had the most significant association with resistance to GVHD therapy and subsequent death without relapse. As compared with patients with low ST2 values at therapy initiation, patients with high ST2 values were 2.3 times as likely to have treatment-resistant GVHD (95% confidence interval [CI], 1.5 to 3.6) and 3.7 times as likely to die within 6 months after therapy (95% CI, 2.3 to 5.9). Patients with low ST2 values had lower mortality without relapse than patients with high ST2 values, regardless of the GVHD grade (11% vs. 31% among patients with grade I or II GVHD and 14% vs. 67% among patients with grade III or IV GVHD, P<0.001 for both comparisons). Plasma ST2 values at day 14 after transplantation were associated with 6-month mortality without relapse, regardless of the intensity of the conditioning regimen.nnnCONCLUSIONSnST2 levels measured at the initiation of therapy for GVHD and during the first month after transplantation improved risk stratification for treatment-resistant GVHD and death without relapse after transplantation. (Funded by the National Institutes of Health.)

Elafin is a biomarker of graft-versus-host disease of the skin.

Plasma elafin concentrations correlate with graft-versus-host disease of the skin and long-term survival. Progress toward biomarker commercialization requires the discovery, qualification, verification, optimization, and clinical validation of a candidate before it is incorporated into existing therapeutic diagnostic platforms. The tremendous value that could be derived from the advancement of methods to detect disease at earlier and more treatable stages puts this pipeline approach at the forefront of biomarker development. However, to date there are no clear success stories in which discovery proteomics has led to a deployed protein biomarker. There is no polymerase chain reaction equivalent available to detect, quantify, and amplify proteins. Rather, proteomics-based biomarker discovery across a wide assortment of diseases is enabled by technologies such as mass spectrometry to sift through a large span of complex analytes at variable concentrations. Now, Paczesny and colleagues use a mass spectrometry–based technique to unambiguously identify candidate plasma biomarkers of skin acute graft-versus-host disease (GVHD)—the primary cause of nonrelapse mortality after bone marrow transplantation (BMT). Rashes are common after BMT and can be caused by a variety of reasons, but because the consequences of GVHD are serious, physicians initiate treatment of suspected GVHD without a bona fide confirmed diagnosis. In the discovery set of this work, the authors examined plasma samples from patients who had received BMT with and without clinical diagnosis of skin GVHD, and found that in patients with skin GVHD, the concentration of one lead marker, elafin, was three times as high. In a follow-up independent validation of 492 BMT patients, skin biopsies stained with elafin stratified the patients consistently according to GVHD parameters, and elafin plasma concentrations were concordantly higher in patients with GVHD. The specificity and sensitivity of elafin relative to other markers revealed that it was the single best discriminator for the diagnosis of GVHD in BMT patients with a rash, and was correlated with the severity of the disease. Elafin concentrations also correlated with the eventual maximum grade of GVHD and with nonrelapse mortality. These results show that elafin concentrations may serve as a noninvasive diagnostic test as well as a prognostic marker in determining GVHD grading in the clinic. Graft-versus-host disease (GVHD), the major complication of allogeneic bone marrow transplantation, affects the skin, liver, and gastrointestinal tract. There are no plasma biomarkers specific for any acute GVHD target organ. We used a large-scale quantitative proteomic discovery procedure to identify biomarker candidates of skin GVHD and validated the lead candidate, elafin, with enzyme-linked immunosorbent assay in samples from 492 patients. Elafin was overexpressed in GVHD skin biopsies. Plasma concentrations of elafin were significantly higher at the onset of skin GVHD, correlated with the eventual maximum grade of GVHD, and were associated with a greater risk of death relative to other known risk factors (hazard ratio, 1.78). We conclude that elafin has significant diagnostic and prognostic value as a biomarker of skin GVHD.

Frequency of CD4+CD25hiFOXP3+ Regulatory T Cells Has Diagnostic and Prognostic Value as a Biomarker for Acute Graft-versus-Host-Disease

The relationship between regulatory T cells (Tregs) and acute graft-versus-host disease (aGVHD) in clinical allogeneic bone marrow transplantation (BMT) recipients is not well established. We conducted a prospective analysis of peripheral blood Tregs as determined by the frequency of CD4(+)CD25(hi)FOXP3(+) lymphocytes in 215 BMT patients. Autologous BMT patients (N = 90) and allogeneic BMT patients without GVHD (N = 65) had similar Treg frequencies, whereas allogeneic patients with GVHD (N = 60) had Treg frequencies that were 40% less than those without GVHD. Treg frequencies decreased linearly with increasing grades of GVHD at onset, and correlated with eventual maximum grade of GVHD (P < .001). In addition, frequency of Tregs at onset of GVHD predicted the response to GVHD treatment (P = .003). Patients with Treg frequencies less than the median had higher nonrelapse mortality (NRM) than patients with Tregs greater than the median, but experienced equivalent relapse mortality, resulting in an inferior survival at 2 years (38% versus 63%, P = .03). Treg frequency may therefore have important prognostic value as a biomarker of aGVHD.

Change in plasma tumor necrosis factor receptor 1 levels in the first week after myeloablative allogeneic transplantation correlates with severity and incidence of GVHD and survival

Acute graft-versus-host disease (GVHD) remains a significant cause of mortality after hematopoietic cell transplantation (HCT). Tumor necrosis factor-alpha (TNF-alpha) mediates GVHD by amplifying donor immune responses to host tissues and by direct toxicity to target organs. We measured TNF receptor 1 (TNFR1) as a surrogate marker for TNF-alpha in 438 recipients of myeloablative HCT before transplantation and at day 7 after transplantation. Increases in TNFR1 levels more than or equal to 2.5 baseline correlated with eventual development of GVHD grade 2 to 4 (58% vs 32%, P < .001) and with treatment-related mortality (39% vs 17%, P < .001). In a multivariate analysis including age, degree of HLA match, donor type, recipient and donor sex, disease, and status at HCT, the increase in TNFR1 level at day 7 remained a significant predictor for outcome. Measurement of TNFR1 levels early after transplantation provides independent information in advance of important clinical outcomes, such as GVHD and death.

Pathogenesis and Management of Graft-versus-Host Disease

Allogeneic hematopoietic cell transplantation (HCT) is an important therapeutic option for various malignant and nonmalignant conditions. As allogeneic HCT continues to increase, greater attention is given to improvements in supportive care, infectious prophylaxis, immunosuppressive medications, and DNA-based tissue typing. However, graft versus host disease (GVHD) remains the most frequent and serious complication following allogeneic HCT and limits the broader application of this important therapy. Recent advances in the understanding of the pathogenesis of GVHD have led to new approaches to its management, including using it to preserve the graft versus leukemia effect following allogeneic transplant. This article reviews the important elements in the complex immunologic interactions involving cytokine networks, chemokine gradients, and the direct mediators of cellular cytotoxicity that cause clinical GVHD, and discusses the risk factors and strategies for management of GVHD.

Plasma biomarkers of lower gastrointestinal and liver acute GVHD

The lower gastrointestinal tract (LGI) and liver are the GVHD target organs most associated with treatment failure and nonrelapse mortality. We recently identified regenerating islet-derived 3-α (REG3α) as a plasma biomarker of LGI GVHD. We compared REG3α with 2 previously reported GI and liver GVHD diagnostic biomarkers, hepatocyte growth factor (HGF) and cytokeratin fragment 18, in 954 hematopoietic cell transplantation patients. All 3 biomarkers were significantly elevated in LGI GVHD compared with non-GVHD diarrhea; REG3α discerned LGI GVHD from non-GVHD diarrhea better than HGF and cytokeratin fragment 18. Although all 3 biomarkers predicted nonresponse to therapy at day 28 in LGI GVHD patients, only REG3α and HGF concentrations predicted 1-year nonrelapse mortality (P = .01 and P = .02, respectively). Liver GVHD without GI involvement at GVHD onset and non-GVHD liver complications were uncommon; all 3 biomarkers were elevated in liver GVHD, but did not distinguish GVHD from other causes of hyperbilirubinemia.

Acute graft-versus-host disease: new treatment strategies.

Purpose of reviewGraft-versus-host disease (GVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation (HCT), despite improvements in our understanding of its pathophysiology as well as the generation of new monoclonal antibodies, immunomodulatory chemotherapy, cellular therapeutics and supportive care. Herein, we review therapies that have proven effective as well as newer agents that have recently improved GVHD response rates and survival following HCT. Recent findingsNovel approaches to prevent or treat GVHD are often based on evidence from experimental models. Our understanding of the pathophysiology of GVHD may lead to the development of innovative strategies that target both soluble and cellular effectors. Among such agents are sirolimus, anti-tumor necrosis factor antibodies, anti-LFA-3–IgG fusion protein, extracorporeal photopheresis, mesenchymal stem cells and regulatory T cells. SummaryObstacles to the improvement of HCT include the tight linkage between GVHD toxicity and the beneficial graft-versus-leukemia (GVL) effect, as well as the impairment of immune reconstitution by immunomodulatory drugs leading to life-threatening infections. The design of newer phase I/II clinical trials are underway. Future therapies are likely to include modulation of cell types that play key roles in the GVH process, including regulatory T cells, dendritic cells, natural killer T cells and B cells.

Extramedullary relapse of acute myeloid leukemia following allogeneic hematopoietic stem cell transplantation: incidence, risk factors and outcomes

Extramedullary relapse after allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia is a contributor to post-transplant mortality but risk factors for, and outcomes of, this condition are not well characterized. We analyzed 257 consecutive patients undergoing allogeneic stem cell transplantation for acute myeloid leukemia at our institution to characterize extramedullary relapse, identify predictive variables and assess outcomes. The 5-year cumulative incidence of isolated extramedullary or bone marrow relapse was 9% and 29%, respectively. Extramedullary relapse occurred later than marrow relapse and most frequently involved skin and soft tissue. Factors predictive of extramedullary relapse after transplantation included previous extramedullary disease, French-American-British classification M4/M5 leukemia, high risk cytogenetics, and advanced disease status at the time of transplantation. Children were more likely than adults to develop extramedullary relapse, a finding probably explained by an overrepresentation of extramedullary disease prior to transplantation and M4/M5 leukemia in children. Acute graft-versus-host disease was not protective against relapse. Unlike medullary relapse, chronic graft-versus-host disease was not protective against extramedullary relapse. The survival rate after extramedullary relapse was 30% at 1 year and 12% at 2 years. Extramedullary relapse is a significant contributor to mortality after allogeneic transplantation for acute myeloid leukemia and appears to be resistant to the immunotherapeutic effect of allogeneic grafting. Effective strategies for patients with extramedullary relapse are needed to improve outcomes after transplantation.

TNF-Inhibition with Etanercept for Graft-versus-Host Disease Prevention in High-Risk HCT: Lower TNFR1 Levels Correlate with Better Outcomes

Graft-versus-host disease (GVHD) causes most non-relapse mortality (NRM) after alternative donor (unrelated and mismatched related) hematopoietic cell transplant (HCT). We previously showed that increases in day +7 TNF-receptor-1 (TNFR1) ratios (posttransplantation day +7/pretransplantation baseline) after myeloablative HCT correlate with outcomes including GVHD, NRM, and survival. Therefore, we conducted a phase II trial at 2 centers, testing whether the addition of the TNF-inhibitor etanercept (25 mg twice weekly from start of conditioning to day +56) to standard GVHD prophylaxis would lower TNFR1 levels, reduce GVHD rates, and improve NRM and survival. Patients underwent myeloablative HCT from a matched unrelated donor (URD; N = 71), 1-antigen mismatched URD (N = 26), or 1-antigen mismatched related donor (N = 3) using either total body irradiation (TBI)-based conditioning (N = 29) or non-TBI-based conditioning (N = 71). Compared to historical controls, the increase in posttransplantation day +7 TNFR1 ratios was not altered in patients who received TBI-based conditioning, but was 40% lower in patients receiving non-TBI-based conditioning. The latter group experienced relatively low rates of severe grade 3 to 4 GVHD (14%), 1-year NRM (16%), and high 1-year survival (69%). These findings suggest that (1) the effectiveness of TNF-inhibition with etanercept may depend on the conditioning regimen, and (2) attenuating the expected rise in TNFR1 levels early posttransplantation correlates with good outcomes.

Hematopoietic stem cell transplantation for severe congenital neutropenia

Purpose of reviewHematopoietic stem cell transplantation (HCT) is the only curative option for patients with severe congenital neutropenia (SCN). Transplant success is dependent on identifying at-risk patients and proceeding to transplant before the development of severe infections or malignant transformation. This review focuses on recent advancements in risk stratification of SCN patients, indications for HCT, and review of published transplant studies. Recent findingsPatients with poor neutrophil response despite high doses of granulocyte colony-stimulating factor (G-CSF) are at greatest risk for malignant transformation. Other studies demonstrate elevated risk with mutations in the G-CSF receptor gene and a specific mutation in the ELANE gene. These patients are at high-risk of sepsis or leukemia development and should proceed to transplant with best available donor. As recent published studies demonstrate, HCT is highly successful in patients without leukemia and, therefore, may be considered in selected low-risk patients given the life-long risk of malignancy and infection. SummaryThe decision whether to proceed to HCT in healthy patients maintained on G-CSF is difficult. As transplant-related mortality continues to decrease, the role of transplant in SCN is likely to expand to more patients.