Stargardt disease: towards developing a model to predict phenotype

Stargardt disease is an ABCA4-associated retinopathy, which generally follows an autosomal recessive inheritance pattern and is a frequent cause of macular degeneration in childhood. ABCA4 displays significant allelic heterogeneity whereby different mutations can cause retinal diseases with varying severity and age of onset. A genotype–phenotype model has been proposed linking ABCA4 mutations, purported ABCA4 functional protein activity and severity of disease, as measured by degree of visual loss and the age of onset. It has, however, been difficult to verify this model statistically in observational studies, as the number of individuals sharing any particular mutation combination is typically low. Seven founder mutations have been identified in a large number of Caucasian Afrikaner patients in South Africa, making it possible to test the genotype–phenotype model. A generalised linear model was developed to predict and assess the relative pathogenic contribution of the seven mutations to the age of onset of Stargardt disease. It is shown that the pathogenicity of an individual mutation can differ significantly depending on the genetic context in which it occurs. The results reported here may be used to identify suitable candidates for inclusion in clinical trials, as well as guide the genetic counselling of affected individuals and families.     

Lymphocyte transformation test detects a response to Campylobacter jejuni antigens in patients with Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is an immune-mediated polyneuropathy. Campylobacter jejuni-associated gastrointestinal infection is identified as a major precipitating agent of GBS; however, a standard test to diagnose this infection in patients with GBS is lacking. The aim of the present study was to evaluate an outer membrane protein (OMP)-based lymphocyte transformation test (LTT) for the diagnosis of C. jejuni infection in GBS. Forty patients with GBS, age and gender matched 52 healthy controls (HC) and 46 disease controls (DC) were analyzed for C. jejuni infection by culture, polymerase chain reaction (PCR) and LTT. Lymphocytes at concentration of 1 × 10⁶/well isolated from GBS patients and controls were stimulated with 20 μg/ml of C. jejuni OMP, and ³H-thymidine was incorporated to measure cell proliferation. LTT detected significantly higher C. jejuni infection compared to culture (77.5 vs. 2.5%; P < 0.05) and PCR (77.5 vs. 22.5%; P < 0.05). The cutoff value of lymphocyte proliferation by receiver operating characteristic (ROC) curve of 2.5 had 77.5% sensitivity and 96.5% specificity. Area under ROC curve was 0.92. The mean SI of the cell proliferation for GBS cases was significantly higher than the controls (GBS vs. HC; P < 0.001, GBS vs. DC; P < 0.001). LTT appears to be a sensitive tool for detecting preceding C. jejuni infection in GBS patients with reasonable sensitivity and specificity. It is possible that the activated lymphocytes might play role in the pathogenesis of neuronal damage in GBS.     

Lenalidomide plus dexamethasone vs. lenalidomide plus melphalan and prednisone: a retrospective study in newly diagnosed elderly myeloma

Background: The goal of this retrospective study was to compare the efficacy and toxicity of lenalidomide–dexamethasone (len/dex) vs. melphalan–prednisone–lenalidomide (MPR) as upfront therapy for newly diagnosed elderly patients with myeloma. Methods: Data from 51 patients enrolled in an Italian phase I/II trial and treated with MPR were analyzed and compared with data from 38 patients, seen at the Mayo Clinic, treated with len/dex and enrolled in phase II/III trials. Results: On intention‐to‐treat analysis, time to progression (median: 24.7 vs. 27.5 months in MPR and len/dex groups, respectively, P = 0.903), progression‐free survival (median: 24.7 vs. 27.5 months in MPR and len/dex groups, respectively, P = 0.926), and overall survival (2‐yr overall survival: 86.2% in MPR vs. 89.1% in len/dex, P = 0.730) were not significantly different between the two groups. Results were confirmed when the analysis was restricted to MPR and len/dex matched pair mates. Hematologic grade 3–4 toxicities were more common with MPR (neutropenia: 66.7% vs. 21.1%, P < 0.001; thrombocytopenia: 31.4% vs. 2.6%, P < 0.001). Grade 3–4 gastrointestinal events (13.2% vs. 3.9%, P = 0.132), thrombotic events (13.2% vs. 5.9%, P = 0.279), and fatigue (10.5% vs. 3.9%, P = 0.395) were more common with len/dex. Conclusions: Results show that both MPR and len/dex are efficacious regimens for elderly patients with myeloma. Randomized trials are needed to confirm these results.     

Idiotype‐pulsed antigen presenting cells following autologous transplantation for multiple myeloma may be associated with prolonged survival

Vaccines are attractive as consolidation therapy after autologous stem cell transplantation (ASCT) for multiple myeloma (MM). We report the results of a phase II trial of the immunotherapeutic, APC8020 (Mylovenge?), given after ASCT for MM. We compared the results with that of other patients with MM who underwent ASCT at Mayo Clinic during the same time period. Twenty‐seven patients were enrolled on the trial between July, 1998 and June, 2001, and the outcomes were compared to that of 124 consecutive patients transplanted during the same period, but not enrolled on the trial. The median (range) follow‐up for patients still alive from the vaccine trial is 6.5 (2.9–8 years), and 7.1 (6–8 years) in the control group. The median age was 57.4 range (36.1–71.3) in the DB group and 56.4 (range, 30–69) in the trial group. Known prognostic factors including PCLI, B2M, and CRP were comparable between the groups. The median overall survival for the trial patients was 5.3 years (95% CI: 4.0 years—N/A) compared to 3.4 years (95% CI: 2.7–4.6 years) for the DB group (P = 0.02). The median time to progression and progression‐free survival for the trial group was similar to the DB group. Although not a controlled trial, the vaccines given after ASCT appear to be associated with improved overall survival compared to historical controls. This approach warrants further investigation to confirm this and define the role of vaccine therapy in myeloma. Am. J. Hematol. 2009. © 2009 Wiley‐Liss, Inc.     

Impact of lenalidomide therapy on stem cell mobilization and engraftment post-peripheral blood stem cell transplantation in patients with newly diagnosed myeloma.

While initial therapies have become highly effective with introduction of lenalidomide and bortezomib and patients may opt for delayed stem cell transplantation, it is important to collect stem cells for future transplant. Given its increasing use as initial therapy, we examined if lenalidomide had any impact on the ability to collect peripheral blood stem cells (PBSC). We studied the entire cohort of patients with myeloma undergoing PBSC mobilization at our institution during a 5-year period, comparing the results between patients receiving different initial therapies. Among those mobilized with granulocyte-colony stimulating factor (G-CSF) alone, there was a significant decrease in total CD34(+) cells collected (P<0.001), average daily collection (P<0.001), day 1 collection (P<0.001) and increased number of aphereses (P=0.004) in patients treated with lenalidomide compared to those receiving dexamethasone, thalidomide-dexamethasone or VAD. A similar trend was seen in those mobilized with chemotherapy and G-CSF. A trend was seen towards decreased PBSC yield with increasing duration of lenalidomide therapy as well as increasing age (P=0.002). There was no effect on quality of PBSC collected based on similar engraftment across all groups. We recommend collection of PBSC within 6 months of initiation of therapy with lenalidomide containing regimens to minimize the risk of mobilization failures.     

Evidence for a functional association between phosphatidylinositol 3-kinase and c-src in the spreading response of osteoclasts to colony-stimulating factor-1

Osteoclasts are bone-resorbing cells whose normal function depends in part upon their ability to migrate over the bone surface to initiate new sites of bone resorption. The growth factor/cytokine, colony-stimulating factor-1 (CSF-1), potently stimulates osteoclast motility, in a c-src-dependent fashion. The intracellular signaling molecules that participate with c-src in CSF-1-induced remodeling of the osteoclast cytoskeleton have not been identified. Here we demonstrate, using the inhibitors wortmannin and LY294002, that activation of phosphatidylinositol 3-kinase (PI3-K) is required for CSF-1-induced spreading in osteoclasts. After CSF-1 treatment of osteoclast-like cells, PI3-K activity associated with the CSF-1 receptor c-fms, is increased, and the 85-kDa regulatory subunit of PI3-K and c-src coimmunoprecipitate. CSF-1 induces redistribution of PI3-K to the periphery of the cell. The association between p85 and c-src is due in part to a direct interaction between the proline-rich sequences of p85 and the SH3 domain of c-src. In vitro, the c-src SH3 domain stimulates PI3-K activity. Taken together, the current data suggest that c-src, via its SH3 domain, may participate in CSF-1-induced activation of PI3-K and that PI3-K and c-src are in the signaling pathway that subserves CSF-1-induced cytoskeletal changes in osteoclasts.