Association of HLA polymorphisms with post-transplant lymphoproliferative disorder in solid-organ transplant recipients

The association between HLA polymorphisms and PTLD was investigated in a case-control study, comparing 110 predominantly adult solid-organ transplant recipients who developed PTLD to 5601 who did not. Donor and recipient HLA were analyzed. We detected a significant association between recipient HLA-A26 and the development of PTLD (OR 2.74; p = 0.0007). In Caucasian recipients, both recipient and donor HLA-A26 were independently associated with development of PTLD (recipient A26 OR 2.99; p = 0.0004, donor A26 OR 2.81; p = 0.002). Analysis of HLA-A and -B haplotypes revealed that recipient HLA-A26, B38 haplotype was strongly correlated with a higher incidence of EBV-positive PTLD (OR 3.99; p = 0.001). The common ancestral haplotype HLA-A1, B8, DR3, when carried by the donor, was protective against PTLD (OR 0.41; p = 0.05). Several other HLA specificities demonstrated associations with clinical and pathological characteristics as well as survival. These findings demonstrate the importance of HLA polymorphisms in modulating the risk for PTLD, and may be useful in risk stratification and development of monitoring and prophylaxis strategies.

Reduction of immunosuppression as initial therapy for posttransplantation lymphoproliferative disorder(★)

Reduction of immunosuppression (RI) is commonly used to treat posttransplant lymphoproliferative disorder (PTLD) in solid organ transplant recipients. We investigated the efficacy, safety and predictors of response to RI in adult patients with PTLD. Sixty-seven patients were managed with RI alone and 30 patients were treated with surgical excision followed by adjuvant RI. The response rate to RI alone was 45% (complete response-37%, partial response-8%). The relapse rate in complete responders was 17%. Adjuvant RI resulted in a 27% relapse rate. The acute rejection rate following RI-containing strategies was 32% and a second transplant was feasible without relapse of PTLD. The median survival was 44 months in patients treated with RI alone and 9.5 months in patients who remained on full immunosuppression (p = 0.07). Bulky disease, advanced stage and older age predicted lack of response to RI. Survival analysis demonstrated predictors of poor outcome-age, dyspnea, B symptoms, LDH level, hepatitis C, bone marrow and liver involvement. Patients with none or one of these factors had a 3-year overall survival of 100% and 79%, respectively. These findings support the use of RI alone in low-risk PTLD and suggest factors that predict response and survival.

Effect of bexarotene on platelet counts in patients undergoing cancer treatment: An analysis of clinical trials in lung cancer and leukemia

e20533

Background: Bexarotene (Bex) is an oral retinoid X receptor agonist with activity against cutaneous T cell lymphoma and currently under investigation for other malignancies. In patients receiving this agent for acute myeloid leukemia (AML), we noted increases in platelet counts. We therefore reviewed the available clinical trial data on Bex and its effects on platelet counts. Methods: We analyzed platelet count data from 3 Bex clinical trials encompassing non-small cell lung cancer (NSCLC) and AML. Results: In two phase III trials of Bex in NSCLC, patients underwent carboplatin + paclitaxel (CarP, n=587) or cisplatin + vinorelbine (CisV, n=613) and were randomized to receive concurrent Bex or placebo. More patients on Bex than on placebo had an increase in platelet count of at least 50 K/uL (55% vs. 27% for CarP, p<0.0001; 81% vs. 66% for CisV, p<0.0001) over pre-treatment baseline. The median increase in platelet count was higher on Bex than on placebo (69 vs 0 K/uL for CarP, p<0.0001; 168 vs. 95 K/uL for CisV, p<0.0001) and was maintained while on treatment. In both NSCLC trials, the median time to platelet increase >50 K/uL on Bex was 22 days. Similar findings were seen in a phase I monotherapy trial in AML where 5/18 (28%) patients achieved platelet transfusion independence with peak platelet counts of 40–91 K/uL. Conclusions: Clinically significant increases in platelet counts were seen in all 3 clinical trials examined. These data suggest that Bex improves platelet counts in patients with a variety of cancer types, both as monotherapy and with concurrent chemotherapy. Its effect on megakaryopoiesis and its potential role as a supportive care measure should be further evaluated.

[Table: see text]

EBV PCR in the diagnosis and monitoring of posttransplant lymphoproliferative disorder: results of a two-arm prospective trial

While EBV PCR is used in the management of PTLD, the optimal primer set, relative importance of intracellular versus free plasma EBV, and the baseline profile in an organ transplant population remains unclear. We performed a prospective 2-arm trial utilizing an EBV PCR panel measuring LMP-1, EBER-1 and EBNA-1 in both free plasma as well as intracellular whole blood. Control Arm A consisted of 31 lung transplant patients and Arm B consisted of 35 transplant patients being evaluated for possible PTLD. In Arm A, 1/31 (3%) patients developed a transient plasma EBV load. Thirteen of 31 (42%) had detectable intracellular EBV. In Arm B, 17 (49%) patients were diagnosed with PTLD. Thirteen (76%) had EBV-positive PTLD with 12/13 (92%) having detectable EBV by PCR. The EBV PCR panel had a high sensitivity (92%), specificity (72%), positive predictive value (PPV) (71%) and negative predictive value (NPV) (93%) for diagnosing EBV-positive PTLD and followed patients' clinical course well (p < 0.001). Comparing the individual PCR assays, plasma EBNA PCR was superior with high sensitivity (77%), specificity (100%), PPV (100%) and NPV (86%). We conclude that EBV PCR is a useful test for managing PTLD patients. While plasma EBNA PCR is the best single assay for diagnosing and monitoring PTLD, the complete PCR panel is superior for ruling out its presence.

A phase I trial of bexarotene, a retinoid X receptor agonist, in non-M3 acute myeloid leukemia

7061

Background: In vitro, bexarotene inhibits the proliferation of non-M3 AML cell lines and induces differentiation of leukemic blasts. This phase I study was designed to evaluate the safety of escalating doses of bexarotene in patients with non-M3 AML and has completed enrollment. Methods: Bexarotene was administered daily until disease progression occurred. Dose escalation occurred in cohorts of 3–6 patients through 6 dose levels ranging from 100–400mg/m2. Results: 27 patients were enrolled: 19M/8F, median age 69 (range 51–82), 13 prior MDS, 12 primary refractory, median number of induction attempts 2, no prior chemotherapy 3, prior autologous stem cell transplant 5, 26 blood transfusion dependent, 18 platelet transfusion dependent, and 20 neutropenic. Despite prophylactic use of antihyperlipidemic agents, 4 patients developed grade ≥3 hypertriglyceridemia. Two patients developed a syndrome reminiscent of retinoic acid syndrome, consisting of dyspnea, pleural/pericardial effusions, and edema in the setting of a rising neutrophil count. This syndrome resolved with stopping bexarotene and initiating steroids. Evidence of activity was noted with bone marrow blasts decreasing to ≤5% in 4 patients. Seven patients showed evidence of neutrophil response (pretreatment median ANC 364/μL, range 28–1,242/μL, treatment ANC 3,540/μL, range 1,200–26,207/μL). Flow sorted peripheral blood neutrophils were collected from 3 of these patients and examined by FISH. Between 92–100% of neutrophils contained the patient's leukemic cytogenetic abnormality suggesting differentiation of the leukemic blasts. Eleven patients with platelet counts <100,000/μL had increases in their platelet counts >20,000/μL (peak range 40- 292x103/μL). Five of these patients with platelet counts <20,000/μL had improvement to 40–91,000/μL and became transfusion independent. Conclusions: Bexarotene is well tolerated at the dose levels studied. Evidence for clinical activity has been seen as exemplified by improvement in platelet counts, increased neutrophil counts and decreased bone marrow blasts. We postulate that bexarotene may induce leukemic blast differentiation in non-M3 AML and represent a novel non-cytotoxic treatment.

No significant financial relationships to disclose.

A two-arm prospective trial evaluating the ability of EBV PCR to diagnose and monitor posttransplant lymphoproliferative disorder

8057

Background: EBV PCR is known to be useful in the management of patients with PTLD. However, the optimal DNA target, relative importance of peripheral blood intracellular versus free plasma EBV, and baseline profile of these EBV PCR variations in a transplant population remains unclear. This study explored these issues as well as assessed the utility of a 6 assay EBV PCR panel in the management of patients with suspected PTLD. Methods: A prospective 2-arm study was performed. Arm A consisted of 31 patients who underwent lung transplantation. Arm B consisted of 35 patients evaluated for possible PTLD. All patients underwent an initial evaluation with EBV PCR and EBV VCA antibody titer. Arm B patients were evaluated for PTLD with CT scans and biopsies of lesions. All patients in Arm A and those in Arm B with documented PTLD were then followed. For the EBV PCR panel, peripheral blood was separated into plasma and whole blood cells and then DNA was purified. Real time EBV PCR was then performed on both samples using primer sets against LMP, EBER and EBNA. Results: No patients on control Arm A developed PTLD. Seventeen (49%) patients on Arm B were found to have PTLD. Thirteen of 17 (76%) had EBV(+) PTLD. Eighteen Arm B patients were given non-PTLD diagnoses. Of 62 patients evaluable for EBV antibody titers, 60 (97%) had IgG for EBV VCA. In Arm A, only 1/31 (3%) patients developed a transient positive low level plasma EBV load. Fourteen of 31 (42%) had detectable low-level intracellular EBV. In patients with EBV(+) PTLD, 11/13 had EBV in plasma and intracellular samples, 1 had intracellular EBV only and 1 patient with isolated CNS PTLD had a negative EBV panel. The EBV PCR panel had high sensitivity (92%) and specificity (67%) for diagnosing EBV(+) PTLD. Comparing the individual PCR assays, whole blood EBER had the best sensitivity (92%) and plasma EBNA & EBER had the best specificity (100%). The EBV PCR panel tracked patient's clinical course well (p=0.06) as they proceeded through treatment. EBV plasma (p=<0.01) and whole blood (p=0.04) copy numbers by EBNA PCR inversely correlated with EBV VCA IgG titers. Conclusion: Peripheral blood EBV PCR is useful in the diagnosis and monitoring of patients with EBV(+) PTLD.

No significant financial relationships to disclose.

Effect of rituximab (R) on clinical outcomes after autologous stem cell transplantation (ASCT) in pts with relapsed or refractory diffuse large B-cell lymphoma (DLBCL)

8122

Background: First-line chemotherapy cures ∼50% of pts with DLBCL, while salvage therapy followed by ASCT can cure another ∼30%. R significantly improves response rates to 1st line therapy. This retrospective study was designed to test the hypotheses that: 1) ASCT is effective in pts relapsed after R-chemotherapy and 2) addition of R to salvage improves outcomes after ASCT. Methods: We identified 84 pts with relapsed/refractory DLBCL who underwent ASCT at our institution between 1990 and 2006. In all, 32% received a R-chemo 1st line regimen and 27% received R with salvage. The median age at ASCT was 49 yrs and the median time from diagnosis to ASCT was 16 mos. High-dose regimens included BCV (48%), BEAM (8%) and alkylator/TBI (20%). Results: Overall response rate (ORR) after ASCT was 52%, with 37% of pts in CR by day 100. Among those in CR, 16% had a CR pre-ASCT, 72% had a lesser response, and 9% were chemo-resistant. The addition of R to salvage (23/84 pts) was favorably associated with ORR after ASCT (OR: 5.2, 95% CI: 1.1 - 25, p=0.029), even in pts who had failed a prior R regimen (p=0.013). Other factors favorably associated with ORR were response to salvage (p=0.046) and time to ASCT >12 mos (p=0.017). At last f/u (med: 22 mos, iqr: 7 - 55 mos), event-free (EFS) and overall survival (OS) were both 35%. The only factor associated with EFS and OS in univariate and multivariate analyses was ORR after ASCT (HR: 0.16, 95% CI: 0.07 - 0.37, p<0.001 and HR: 0.12, 95% CI: 0.05 - 0.28, p<0.001 respectively). Age at ASCT, time to ASCT, year of ASCT, mobilization/conditioning regimen, and failure of a R-chemo regimen were not associated with EFS or OS. Conclusions: Pts with DLBCL who have failed a R-chemo first-line regimen derive an equal benefit from ASCT as pts who are R-naïve, with significant long-term EFS and OS. Additionally, inclusion of R in salvage therapy prior to ASCT provides superior response rates, even after a failed prior R-chemo regimen. These results confirm the benefit of ASCT for pts with DLBCL in the rituximab era and argue for the incorporation of R and related agents in studies of high-dose therapy and ASCT.

No significant financial relationships to disclose.

Outpatient autologous stem cell transplants for selected patients with myeloma: Morbidity, mortality, and duration of hospitalization

7104

Background: High-dose melphalan with autologous stem cell support improves survival for patients with myeloma but often requires prolonged inpatient hospitalization. Short hospitalization with close follow-up may reduce complications, cost, and duration of total hospitalization for selected patients with good performance status and social support. Methods: We reviewed all initial autologous transplants for myeloma from 1/03–4/06, categorized by length of initial hospitalization as brief stay (≤4 days) or prolonged stay (≥5 days). Clinical selection for a brief stay had been based on a combination of age; cardiac, pulmonary, and renal function; performance status; availability of caregivers at home; distance from our medical center; and patient preference. We reviewed the post-transplant course to 100 days and calculated cumulative hospitalization by adding length of initial hospitalization to that of subsequent readmissions within 100 days. Results: 148 patients received an initial transplant for myeloma: 64 were selected for brief stay and 84 for prolonged stay. There were no significant differences in age or in renal function, Durie-Salmon stage, or B2-microglobulin at diagnosis. Brief stay patients were discharged home after stem cell reinfusion, with first follow-up scheduled 3–14 days later. Care at home included a nurse visit after discharge, intravenous fluids and ondansetron, and oral antibiotics, with blood work twice weekly. 46% of brief stay patients required readmission during the first 100 days and had a median of 8.5 cumulative hospital days post-transplant, as compared to 18 days for prolonged stay patients (p=0.0001). There were fewer documented infections among brief stay patients (29.7% vs 50.0%, p=0.01) and fewer admissions to intensive care units (0 vs 6.0%, p=0.047). The groups had similar rates of bleeding (1.6% vs 4.8%, p=0.3) and thrombosis (3.1% vs 8.3%, p=0.2). No patients in the brief stay group died within 100 days, while mortality in the prolonged stay group was 4.8% (p=0.08). Conclusion: Selected patients receiving an autologous stem cell transplant for treatment of myeloma can be managed with brief initial hospitalization and outpatient follow-up, with low morbidity and mortality.

No significant financial relationships to disclose.

A phase I trial of bexarotene, a retinoid X receptor agonist, in relapsed or refractory non-M3 acute myeloid leukemia (AML)

6567

Background: In vitro, bexarotene inhibits the proliferation of non-M3 AML cell lines and induces differentiation of leukemic blasts. This phase I study was designed to evaluate the safety of escalating doses of bexarotene in patients with relapsed or refractory non-M3 AML. Methods: Bexarotene was administered orally daily until disease progression occurred. Five dose levels ranging from 100 to 300 mg/m2 were planned. Dose escalation occurred in cohorts of 3–6 patients based on dose-limiting toxicity. Results: Fourteen patients have been enrolled in 4 dose cohorts (100–250 mg/m2) with enrollment demographics: 8M/6F, median age 63 (range 51–76), 6 prior MDS, 6 primary refractory, median number of induction attempts 2, prior autologous stem cell transplant 4, 14 blood transfusion dependent, 12 platelet transfusion dependent, and 12 neutropenic. Two patients developed hypothyroidism. Despite prophylactic use of antihyperlipidemic agents, 4 patients developed grade 2 or 3 hypertriglyceridemia. Two patients developed a syndrome reminiscent of retinoic acid syndrome, consisting of dyspnea/hypoxia, pleural/pericardial effusions, weight gain/edema and dry cough in the setting of a rapidly rising neutrophil count. This syndrome resolved within 48 hours of stopping bexarotene and initiating steroids. One patient had a WBC rise from 1.7×103/μL (ANC 1,037/μL, 18% blasts) pre-bexarotene to 23.9×103/μL (ANC 19,368/μL, 3% blasts) during this syndrome. Flow cell sorted peripheral blood neutrophils all contained this patient’s original t(8;21) by FISH, suggesting differentiation of the leukemic blasts. Bone marrow blasts decreased to ≤5% in two patients. Three platelet transfusion dependent patients had increases in their platelet counts to a peak count of 40–292×103/μL on bexarotene. Conclusion: Daily oral bexarotene is well tolerated at the dose levels studied to date. Early evidence for activity has been seen as exemplified by improvement in platelet counts, decreased bone marrow blast counts, blast differentiation and possible retinoic acid syndrome. Patient enrollment is ongoing.

[Table: see text]

Serum LDH predicts response rate, response duration, and survival of patients (pts) with relapsed/refractory non-Hodgkin’s lymphoma (NHL) treated with 131I-tositumomab (131I-Tab) or 90Y ibritumomab tiuxetan (90Y-Iab) radioimmunotherapy (RIT)

17520

Background: Although both 131I-Tab and 90Y-Iab are approved for treatment of pts with relapsed or refractory low-grade, follicular, or transformed NHL, a prospective randomized comparison of these two forms of RIT has not been performed. We retrospectively reviewed our experience using either agent in pts with NHL. Methods: Sixty-one pts with NHL who were treated with a single course of 131I-Tab (N = 22) or 90Y-Iab (N = 39) between 1999 and 2005 were included in this analysis. The median age was 61 y (range 21–83 y) and the median number of prior therapies was 5 (range 1–13). Overall, 27 pts had indolent NHL (20 follicular grade 1/2, 4 small lymphocytic, and 3 marginal zone), while 34 pts had aggressive NHL (22 diffuse large cell, 10 mantle cell, and 2 follicular grade 3). Among pts, 75% had stage III/IV disease, 52% had an elevated serum LDH, and 38% had bulky disease (>5 cm). These characteristics were similar for pts receiving either 131I-Tab or 90Y-Iab, with the exception of elevated serum LDH (64% vs. 33%, p = 0.02). Median follow up was 21 mos (range 3–55). Results: The overall response rate (ORR) was 44% with complete response (CR) in 21% of pts. The median time to progression (TTP) was 5 mos for all pts, 9 mos for responders, and 14 mos for CRs (range 4–55). Patients with indolent NHL had no difference in ORR, CR, or TTP from pts with aggressive NHL, but had a significantly longer OS (HR 0.37, p = 0.01). Elevated LDH was the only significant predictor of ORR (31% vs. 57%, p = 0.04). In multivariable analysis, elevated LDH was adversely associated with TTP (HR 2.0, p = 0.02) and OS (HR 2.7, p = 0.02) among both subgroups of NHL. We did not discern a difference in ORR, CR, TTP, or OS between 131I-Tab and 90Y-Iab, even when stratifying for serum LDH. Conclusions: RIT produced high response rates in heavily pre-treated pts with indolent or aggressive NHL. Elevated LDH is the most significant prognostic factor for ORR, TTP and OS in this population. Patients with an elevated LDH should be considered for alternative treatment approaches or clinical trials, including RIT in combination with chemotherapy or transplant.

[Table: see text]

Treatment of PTLD with rituximab or chemotherapy

Information regarding treatment of post-transplant lymphoproliferative disease (PTLD) beyond reduction in immunosuppression (RI) is limited. We retrospectively evaluated patients receiving rituximab and/or chemotherapy for PTLD for response, time to treatment failure (TTF) and overall survival (OS). Thirty-five patients met inclusion criteria. Twenty-two underwent rituximab treatment, with overall response rate (ORR) 68%. Median TTF was not reached at 19 months and estimated OS was 31 months. In univariable analysis, Epstein-Barr virus (EBV) positivity predicted response and TTF. LDH elevation predicted shorter OS. No patient died of rituximab toxicity and all patients who progressed underwent further treatment with chemotherapy. Twenty-three patients received chemotherapy. ORR was 74%, median TTF was 10.5 months and estimated OS was 42 months. Prognostic factors for response included stage, LDH and allograft involvement by tumor. These factors and lack of complete response (CR) predicted poor survival. Twenty-six percent of the patients receiving chemotherapy died of toxicity. Rituximab and chemotherapy are effective in patients with PTLD who fail or do not tolerate RI. While rituximab is well tolerated, toxicity of chemotherapy is marked. PTLD patients requiring therapy beyond RI should be considered for rituximab, especially with EBV-positive disease. Chemotherapy should be reserved for patients who fail rituximab, have EBV-negative tumors or need a rapid response.

Treatment of PTLD with rituximab or chemotherapy

Information regarding treatment of post-transplant lymphoproliferative disease (PTLD) beyond reduction in immunosuppression (RI) is limited. We retrospectively evaluated patients receiving rituximab and/or chemotherapy for PTLD for response, time to treatment failure (TTF) and overall survival (OS). Thirty-five patients met inclusion criteria. Twenty-two underwent rituximab treatment, with overall response rate (ORR) 68%. Median TTF was not reached at 19 months and estimated OS was 31 months. In univariable analysis, Epstein-Barr virus (EBV) positivity predicted response and TTF. LDH elevation predicted shorter OS. No patient died of rituximab toxicity and all patients who progressed underwent further treatment with chemotherapy. Twenty-three patients received chemotherapy. ORR was 74%, median TTF was 10.5 months and estimated OS was 42 months. Prognostic factors for response included stage, LDH and allograft involvement by tumor. These factors and lack of complete response (CR) predicted poor survival. Twenty-six percent of the patients receiving chemotherapy died of toxicity. Rituximab and chemotherapy are effective in patients with PTLD who fail or do not tolerate RI. While rituximab is well tolerated, toxicity of chemotherapy is marked. PTLD patients requiring therapy beyond RI should be considered for rituximab, especially with EBV-positive disease. Chemotherapy should be reserved for patients who fail rituximab, have EBV-negative tumors or need a rapid response.

Long-term event-free survivors after high-dose therapy and autologous stem-cell transplantation for low-grade follicular lymphoma

Although follicular lymphoma (FL) is generally responsive to conventional-dose chemotherapy, improved survival in patients with this disease has been difficult to demonstrate. High-dose chemo/radiotherapy followed by autologous stem-cell transplantation (ASCT) can improve response rates, although its effects on survival remain controversial. Between 1990 and 2003, we transplanted 49 patients with low-grade FL at our institution. Twenty-two patients (45%) had undergone histologic transformation at the time of ASCT. In all, 44 patients (90%) had relapsed disease and five patients (10%) were resistant to chemotherapy at the time of transplantation. After ASCT, 30 patients (61%) were in complete remission (CR). The median overall survival (OS) has not been reached, while the median event-free survival (EFS) is 2.4 years. At a median follow-up of 5.5 years (longest 12.4 years), a plateau has been reached with 56% of patients remaining alive, and 35% event-free. ASCT was well tolerated except for two (4%) treatment-related deaths. In multivariable analysis, CR after ASCT and age less than 60 years are the best predictors of EFS and OS. ASCT is thus a safe therapeutic approach in FL, resulting in long-term EFS and OS for some patients, even with transformed disease.

Intensive graft-versus-host disease prophylaxis is required after unrelated-donor nonmyeloablative stem cell transplantation

Nonmyeloablative stem cell transplantation (NST) harnesses the graft-versus-tumor effect while minimizing regimen-related toxicity, and can result in donor chimerism and remission. Acute graft-versus-host disease (GVHD) and infections are major complications after sibling NST. Toxicity of unrelated-donor (UD) NST and the most appropriate GVHD prophylaxis in this setting remain poorly defined. We describe 25 patients who received UD-NST conditioned with fludarabine and cyclophosphamide. The first six patients received cyclosporine (Cs) and mycophenolate mofetil (MMF) (n=5) or methotrexate (MTX) (n=1) as GVHD prophylaxis (group 1) and all developed grade III-IV acute GVHD. The next 19 patients received the same conditioning regimen with the addition of alemtuzumab, and all received Cs/MTX post-transplant. Engraftment and donor chimerism were achieved in all but one evaluable patient. In all, 15 patients died: five of six deaths in group 1 were attributable to acute GVHD, while deaths in group 2 were due to infection or progressive disease (P=0.05). The combination of Cs/MMF is inadequate GVHD prophylaxis for UD-NST. The use of Cs, MTX, and alemtuzumab eliminated severe acute GVHD; its impact on response merits further study.

Post-transplant lymphoproliferative disorder: a review

Post-transplant lymphoproliferative disorder (PTLD) represents a spectrum of Epstein-Barr virus-related (EBV) clinical diseases, from a benign mononucleosis-like illness to a fulminant non-Hodgkin's lymphoma. In the setting of hematopoietic stem cell transplantation, PTLD is an often-fatal complication occurring relatively early after transplant. Risk factors for the development of PTLD are well established, and include HLA-mismatching, T-cell depletion, and the use of antilymphocyte antibodies as conditioning or treatment of graft-versus-host disease. Early recognition of PTLD is particularly important in the SCT setting, because PTLD in these patients tends to be rapidly progressive. Familiarity with the clinical features of PTLD and a heightened level of suspicion are critical for making the diagnosis. Surveillance techniques with EBV antibody titers and/or polymerase chain reaction (PCR) may have a role in some high-risk settings. Immune-based therapies such as monoclonal anti-B-cell antibodies, interferon-alpha, and EBV-specific donor T cells, either as treatment for PTLD or as prophylaxis in high-risk patients, represent promising new directions in the treatment of this disease.

Gemtuzumab ozogamicin (Mylotarg) monotherapy for relapsed AML after hematopoietic stem cell transplant: efficacy and incidence of hepatic veno-occlusive disease

Gemtuzumab ozogamicin (GO) (Mylotarg, CMA-676) is a novel chemotherapeutic agent consisting of an anti-CD33 monoclonal antibody linked to calicheamicin, and is associated with a 30% response rate in patients with CD33-positive acute myeloid leukemia (AML) in first relapse. GO therapy has a 20% incidence of grade 3 or 4 hepatotoxicity, and has recently been associated with hepatic veno-occlusive disease (VOD). The efficacy and toxicity of GO in patients with AML who have relapsed after hematopoietic stem cell transplant (HSCT) is unknown, as this population was largely excluded from phase II studies. We reviewed the outcomes of eight consecutive patients with AML who received GO following relapse after HSCT. Two (25%) had responses to GO. One patient, who had had two previous HSCT and prior hyperbilirubinemia, developed severe VOD and died 14 days after GO therapy. The other seven patients did not meet diagnostic criteria for VOD. We conclude that GO can be safe and effective in patients who relapse following HSCT, but that caution is warranted in patients with multiple risk factors for VOD.

Reduction in immunosuppression as initial therapy for posttransplant lymphoproliferative disorder: analysis of prognostic variables and long-term follow-up of 42 adult patients

BACKGROUND

Posttransplant lymphoproliferative disorder (PTLD) is an Epstein-Barr virus-associated malignancy that occurs in the setting of pharmacologic immunosuppression after organ transplantation. With the increased use of organ transplantation and intensive immunosuppression, this disease is becoming more common. We explore reduction in immunosuppression as an initial therapy for PTLD.

METHODS

We analyzed our organ transplant patient database to identify patients with biopsy-proven PTLD who were initially treated with reduction of their immunosuppressive medications with or without surgical resection of all known disease.

RESULTS

Forty-two adult patients were included in this study. Thirty patients were treated with reduction in immunosuppression alone. Twelve patients were treated with both reduction in immunosuppression and surgical resection of all known disease. Thirty-one of 42 patients (73.8%) achieved a complete remission. Of those patients who were treated with reduction in immunosuppression alone, 19 of 30 (63%) responded with a median time to documentation of response of 3.6 weeks. Multivariable analysis showed that elevated lactate dehydrogenase (LDH) ratio, organ dysfunction, and multi-organ involvement by PTLD were independent prognostic factors for lack of response to reduction in immunosuppression. In patients with none of these poor prognostic factors, 16 of 18 (89%) responded to reduction in immunosuppression in contrast to three of five (60%) with one risk factor and zero of seven (0%) with two to three factors present. The analysis also showed that increased age, elevated LDH ratio, severe organ dysfunction, presence of B symptoms (fever, night sweats, and weight loss), and multi-organ involvement by PTLD at the time of diagnosis are independent prognostic indicators for poor survival. With median follow-up of 147 weeks, 55% of patients are alive with 50% in complete remission.

CONCLUSIONS

Reduction in immunosuppression is an effective initial therapy for PTLD. Clinical prognostic factors may allow clinicians to identify which patients are likely to respond to reduction in immunosuppression.

Progressive intermediate-grade non-Hodgkin's lymphoma after high-dose therapy and autologous peripheral stem-cell transplantation: changing the natural history with monoclonal antibody therapy

The prognosis of patients with progressive intermediate-grade non-Hodgkin's lymphoma (NHL) after high-dose chemotherapy and autologous peripheral stem-cell transplantation (PSCT) is poor, with survival measured in months. The advent of monoclonal antibody therapy for NHL has created new options for effective therapy with relatively mild side effects. We report on two patients with progressive intermediate-grade NHL after PSCT who were treated with monoclonal antibody therapy. Both patients initially received rituximab (unlabeled anti-CD20 monoclonal antibody) and were subsequently treated with (90)Y-epratuzumab (yttrium-90-labeled humanized anti-CD22 monoclonal antibody) at relapse. One patient received (90)Y-epratuzumab alone while the other was treated with higher doses in combination with autologous peripheral stem-cell infusion. Both patients achieved a rapid response to the radiolabeled antibody with minimal toxicity. Monoclonal antibody therapy may be an effective and tolerable treatment for progressive NHL after PSCT.

Stem cell transplantation for metastatic breast cancer: analysis of tumor contamination

The purpose of this study was to determine the efficacy, engraftment kinetics, effect of bone marrow tumor contamination, and safety of high-dose therapy and granulocyte-colony stimulating factor (G-CSF) mobilized peripheral blood progenitor cell (PBPC) support for patients with responding metastatic breast cancer. Forty two patients underwent G-CSF (10 microg/kg) stimulated PBPC harvest. PBPC and bone marrow aspirates were analyzed by histologic and immunocytochemical methods for tumor contamination. Thirty-seven patients received high-dose therapy consisting of cyclophosphamide 6 g/m2, thiotepa 500 mg/m2, and carboplatin 800 mg/m2 (CTCb) given as an infusion over 4 d followed by PBPC reinfusion and G-CSF (5 microg/kg) support. No transplant related deaths or grade 4 toxicity was recorded. CD34+ cells/kg infused was predictive of neutrophil and platelet recovery. With a median follow-up of 38 months, three year survival was 44% with relapse-free survival of 19%. Histological bone marrow involvement, found in 10 patients, was a negative prognostic factor and was associated with a median relapse-free survival of 3.5 months. Tumor contamination of PBPC by immunohistochemical staining was present in 22.5% of patients and found not to be correlated with decreased survival. G-CSF stimulated PBPC collection followed by a single course of high dose chemotherapy and stem cell infusion with G-CSF stimulated marrow recovery leads to rapid, reliable engraftment with low toxicity and promising outcome in women with responding metastatic breast cancer.

Combined radiation and chemotherapy in posttransplant lymphoproliferative disorder

The optimal treatment for posttransplant lymphoproliferative disorder which has progressed despite a reduction in immunosuppression has not been defined. We report on two patients with stage I posttransplant lymphoproliferative disorder who developed progressive disease despite a reduction in the level of immunosuppression. Both patients were treated with combined short course CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy followed by involved-field radiation therapy. In both patients, a rapid response was obtained followed by complete remission. Combined modality therapy can be utilized successfully in progressive limited stage posttransplant lymphoproliferative disorder.

Exploring molecular diversity with combinatorial shape libraries

Surface technologies based upon selection of ligands from combinatorial libraries herald a revolution in molecular research and drug discovery. Molecular diversity is generated by random combinations of monomeric building blocks to form polymeric conformers that constitute 'shape libraries'. The media for exploring surfaces of target molecules include synthetic or biological polymers consisting of natural or modified amino acids, nucleotides, carbohydrates and other organic materials. Targets can be any biological surface, including enzymes, antibodies, receptors and other regulatory molecules. The power of combinatorial selection is in finding conceptual leads for designing high-affinity ligands and effector molecules for the analysis and manipulation of biochemical interactions.

In vitro selection of RNA epitopes using autoimmune patient serum

Nucleotide-specific autoimmune epitopes have not been precisely defined despite the fact that certain kinds of DNA and RNA species are known to bind autoantibodies. Our laboratory has used nucleic acid epitope libraries, consisting of randomized RNA pools, to select specific RNA conformers recognized by antibodies, including a peptide-specific antibody. In the present study, serum from a patient with systemic lupus erythematosus was used to select ligands from an RNA epitope library. The selected RNA contained sequences that were found to be similar to regions within the U1 small nuclear RNA, previously shown to react with autoantibodies. Furthermore, the selected RNA epitopes were able to inhibit autoantibody reactivity with specific regions of U1 RNA, thus demonstrating their immunologic cross-reactivity with the natural RNA epitope. Although the origins of nucleic acid-binding autoantibodies are not understood, the identification of these defined U1 RNA epitopes, in regions of the RNA where cell proteins are not known to bind, is most compatible with models of immunologic cross-reactivity or with direct presentation to the immune system rather than with anti-Id models. These experiments demonstrate that RNA epitope libraries may be used to reveal the fine specificity of autoimmune recognition and provide a useful approach to study RNA-protein interactions.

In vitro selection of RNA epitopes using autoimmune patient serum

Nucleotide-specific autoimmune epitopes have not been precisely defined despite the fact that certain kinds of DNA and RNA species are known to bind autoantibodies. Our laboratory has used nucleic acid epitope libraries, consisting of randomized RNA pools, to select specific RNA conformers recognized by antibodies, including a peptide-specific antibody. In the present study, serum from a patient with systemic lupus erythematosus was used to select ligands from an RNA epitope library. The selected RNA contained sequences that were found to be similar to regions within the U1 small nuclear RNA, previously shown to react with autoantibodies. Furthermore, the selected RNA epitopes were able to inhibit autoantibody reactivity with specific regions of U1 RNA, thus demonstrating their immunologic cross-reactivity with the natural RNA epitope. Although the origins of nucleic acid-binding autoantibodies are not understood, the identification of these defined U1 RNA epitopes, in regions of the RNA where cell proteins are not known to bind, is most compatible with models of immunologic cross-reactivity or with direct presentation to the immune system rather than with anti-Id models. These experiments demonstrate that RNA epitope libraries may be used to reveal the fine specificity of autoimmune recognition and provide a useful approach to study RNA-protein interactions.

In vitro selection of an RNA epitope immunologically cross-reactive with a peptide

An antiserum raised against a peptide was used to select a unique RNA species from a degenerate pool of RNAs designed to resemble an autoantibody recognition site in U1 RNA. The peptide and the selected RNA epitope could compete for antibody binding, suggesting that both RNA and peptide epitopes occupy the same or overlapping antigen-combining sites. Thus, the RNA epitope functioned as a specific inhibitor of the antibody-antigen interaction. We demonstrate that the RNA epitope can be used to tag unrelated RNA molecules and also to detect the presence of the antibody. We propose that sequence-specific recognition of RNA by antibodies may involve protein-RNA contacts similar to those occurring in other nucleic acid-binding proteins. In addition, these findings are compatible with the suggestion that nucleic acid-binding autoantibodies may arise through immunological cross-reactivity between proteins and nucleic acids.

U1-snRNP-A protein selects a ten nucleotide consensus sequence from a degenerate RNA pool presented in various structural contexts

The U1snRNP-A (U1-A) protein was used to select specific RNA sequences from a degenerate pool of transcripts using direct RNA binding and polymerase chain reaction amplification (PCR). Sequences were randomized in loops of 10 or 13 nucleotides or as a linear stretch of 25 nucleotides. From all three structural contexts, an unpaired ten nucleotide consensus sequence was obtained. A selected stem-loop structure that resembled the natural U1-A protein binding site on loop II of U1 RNA demonstrated the highest affinity of binding in comparison with the other structural contexts. A data profile of selected sequences identified U1 RNA upon searching the GenBank database. Thus, this method was useful in determining the sequence specificity of an RNA binding protein and may complement the use of phylogenetic comparisons to predict conserved recognition elements. These findings also suggest that the evolutionary conservation of loop II of U1 RNA results from constraints imposed by protein binding.

Total lipid and cholesterol content in the blue crab, Callinectes sapidus Rathbun

Total lipid and cholesterol concentrations in hepatopancreas, gonad and muscle were analyzed for 70 blue crabs. The concentrations were highest in hepatopancreas, then gonad, and muscle was the lowest. In male crabs, the concentrations decreased from the immature stage (feeding and growth stage) to the mature stage (breeding stage), and from August to September (breeding period) in mature males. In female crabs, the concentrations were comparatively high for peelers (pre-molting stage) and mature females in October (pre-spawning migration period). The total lipid and cholesterol concentrations were significantly, positively correlated in both sexes. The total lipid and cholesterol concentrations were independent of both body weight and tissue weight. Exceptions were the immature females whose concentrations in hepatopancreas were negatively correlated with both body weight and hepatopancreas weight, and the mature females whose concentrations in gonads were positively correlated with gonad weight.