Christos Kosmas

Follicular lymphoma immunoglobulin κ light chains are affected by the antigen selection process, but to a lesser degree than their partner heavy chains

Follicular lymphoma cells carry surface immunoglobulin whose heavy chain variable (VH) regions exhibit considerable divergence from the aminoacid sequence predicted by the germline nucleotide sequence as a result of the somatic hypermutation process. The present study examined the extent of somatic hypermutation in follicular lymphoma κ light chain variable region (Vκ) genes about which the available data is limited. DNA extracted from fresh frozen lymph node tissue of 14 patients with follicular lymphoma at diagnosis was subjected to polymerase chain reaction (PCR) amplification aimed at detecting clonal VH and VL (L; light chain) gene rearrangements. Clonal Vκ gene rearrangements were detected in 10/14 cases. Amplified VH and Vκ genes of these 10 cases were directly sequenced by the dideoxy‐chain termination method. In all cases, rearranged VH genes demonstrated numerous mutations clustering in the complementarity determining regions (CDRs), in keeping with previous reports. The degree of divergence of the rearranged Vκ genes from the closest homologous germline Vκ genes varied significantly. Furthermore, two patterns of mutations were observed: (i) in six cases (60%), mutations were most often of the replacement (R) type (changing the aminoacid sequence of the encoded polypeptide) in the CDRs and of the silent (S) type (leaving the aminoacid sequence of the encoded polypeptide unchanged) in the framework regions (FWRs) resulting in R:S ratios significantly greater than would have occurred by chance; (ii) in four cases (40%), very few or no mutations were observed and the distribution of mutations as well as the R:S mutation ratios did not differ significantly from what would have occurred by chance alone. These findings imply that, compared to their partner heavy chains, the κ light chains of follicular lymphoma neoplastic B‐cells surface immunoglobulin (sIg): (i) are less affected by somatic hypermutation; (ii) play a less significant role in the antigen selection process.

Somatic hypermutation of immunoglobulin variable region genes: focus on follicular lymphoma and multiple myeloma

Summary: Analysis of the rearranged immunoglobulin variable region gene hypermutation has provided important information concerning the clonal history and ontogenetic origin of various B‐cell lymphoproliferative disorders. Under the selective pressure of antigen, mutational events in immunoglobulin genes will fine tune survival of B‐cell clones bearing immunoglobulin with high affinity for antigen. Our studies aimed at analyzing neoplastic disorders originating from germinal and post‐germinal center B‐cells: follicular lymphoma and multiple myeloma. respectively. Despite the already acknowledged evidence for a selectable distribution of mutations within the clonal immunoglobulin variable heavy chain genes, very little is known about the contribution of light chains in the process of antigen selection. In follicular lymphoma. a more limited pattern of somatic mutation with less evidence of antigen selection was observed in variable K light chain genes (40%) than in their partner heavy chain genes (80%). In myeloma, hypermutation of variable light chain genes, with a distribution suggestive of antigen selection, was frequently observed. Based on these data and recent reports it appears that the light chain expressed by the clonogenic myeloma B‐cells plays a pivotal role in the antigen selection process. Additionally, abortive K light chain variable region genes in X‐expressing myeloma carried a significant number of somatic mutations indicating that the cell of origin is open to the hypermutation machinery at that particular developmental stage irrespective of antigen selection.

Analysis of the κ light chain variable region in multiple myeloma

The study of immunoglobulin heavy chain gene rearrangements in multiple myeloma has revealed extensive divergence from the germline sequences, but no intraclonal diversity with disease evolution. Our study investigated the state of the rearranged κ light chain variable region (Vκ) gene segments, as well as abortive Vκ family gene usage in cases of multiple myeloma expressing λ light chain. We studied 11 cases of κ and five cases of λ light chain‐expressing multiple myeloma. Total cellular RNA was extracted from the bone marrow of patients with overt disease and subjected to reverse transcription‐polymerase chain reaction (RT‐PCR) analysis to amplify clonally rearranged variable region sequences. Direct nucleotide sequencing by the dideoxy‐chain termination method was performed on the RT‐PCR products. We did not observe preferential usage of certain Vκ gene families. Mutation frequencies of the Vκ segments varied in number. In the majority of cases, extensive somatic mutations occurred within the complementarity determining regions (CDRs) of Vκ, whereas only a limited degree of divergence from the germline was observed in others. In all cases studied, replacement mutations tended to cluster in the CDRs, a finding compatible with an antigen‐driven somatic hypermutation process. In 3/5 cases of λ light‐chain expressing multiple myeloma, abortively rearranged Vκ gene segments were amplified from genomic DNA; in two cases a non‐templated nucleotide insertion rendering the Vκ sequences out‐of‐frame was observed, and in the third a stop codon was identified in the open reading frame of the Vκ sequence. Somatic mutations were observed in all cases of abortive Vκ genes studied; however, their distribution does not suggest selection by antigen.

Molecular analysis of bcl‐1/IgH junctional sequences in mantle cell lymphoma: potential mechanism of the t(11;14) chromosomal translocation

Mantle cell lymphoma (MCL) is characterized by the t(11;14) translocation that juxtaposes the bcl‐1 locus to immunoglobulin (Ig) gene sequences and leads to deregulation of cyclin D1 gene. t(11;14) is thought to result from an error of the recombinase during D‐JH Ig gene assembly; however, data on the underlying mechanism and candidate recombination‐targeting motifs in the major translocation cluster (MTC) of the bcl‐1 gene are lacking.

t(14;18) chromosomal translocation in follicular lymphoma: an event occurring with almost equal frequency both at the D to JH and at later stages in the rearrangement process of the immunoglobulin heavy chain gene locus

bcl‐2/IgH fusion is considered a genetic error which occurs at the diversity (D) to joining (JH) stage of the gene rearrangement process in the immunoglobulin heavy chain (IgH) gene locus. Translocations of the bcl‐2 protooncogene to the IgH locus at ontogenetically later IgH gene rearrangements are thought to represent exceptions. In the present study we analysed the junctional nucleotide sequence of 18 bcl‐2/IgH fusion genes identifiable by polymerase chain reaction performed on DNA extracted from diagnostic lymph node tissue of 14 follicular lymphoma patients. In all clones studied, segments of variable length were found interposed between bcl‐2 and JH gene sequences. Nucleotide sequence data analysis and comparisons performed with the corresponding germline sequences using the GenBank/EMBL database revealed the presence of D segments in most of the bcl‐2/IgH fusion genes under study (13/18). By the same kind of computer‐aided analysis, previously unrecognized D segments were identified in many published junctional sequences. These results suggest that bcl‐2/IgH fusion events are very prevalent in rather more differentiated stages in B‐cell ontogeny than previously recognized.

Survival in patients with stage IV noncardia gastric cancer - the influence of DNA ploidy and Helicobacter Pylori infection

BackgroundPalliative surgery followed by postoperative chemotherapy is a challenging approach in the treatment of stage IV gastric cancer yet patients must be carefully selected on the basis of likely clinical benefit.MethodsThe records of 218 patients with histological diagnosis of gastric adenocarcinoma who underwent palliative surgery followed by postoperative chemotherapy were retrospectively reviewed. Twelve potential prognostic variables including tumour DNA index and serum IgG anti- Helicobacter pylori (HP) antibodies were evaluated for their influence on overall survival by multivariate analysis.ResultsThe median survival was 13.25u2009months [95% Confidence Interval (CI) 12.00, 14.50]. Three factors were found to have an independent effect on survival: performance status (PS) [PS 60–70 vs. 90–100 Hazard Ratio (HR) 1.676; CI 1.171-2.398, pu2009=u20090.005], liver metastases (HR 1.745; CI 1.318-2.310, pu2009<u20090.001), and DNA Index as assessed by Image cytometry (2.2-3.6 vs. >3.6 HR 3.059; CI 2.185-4.283, pu2009<u20090.001 and <2.2 vs. >3.6 HR; 4.207 CI 2.751-6.433 <0.001). HP infection had no statistically significant effect on survival by either univariate or multivariate analysis.ConclusionPoor pre-treatment PS, the presence of liver metastasis and high DNA Index were identified factors associated with adverse survival outcome in patients with Stage IV gastric cancer treated with palliative gastrectomy and postoperative chemotherapy. HP infection had no influence on survival of these patients.

A unique case of splenic marginal zone-cell lymphoma with synchronous clonal T-cell large granular lymphocyte proliferation: an immunologic, immunohistochemical and genotypic study

We describe a case of synchronous splenic marginal zone-cell lymphoma (SMZL) and T-cell large granular lymphocyte leukemia involving the spleen, liver, bone marrow and peripheral blood. The synchronous occurrence of these two processes was documented by morphological, immunophenotypical and molecular (PCR) analyses of all affected tissues. The pathogenetic mechanisms which may be responsible for the concomitant appearance of these two rather infrequent entities in the same anatomic sites are discussed.

Evaluation of DNA ploidy in relation with established prognostic factors in patients with locally advanced (unresectable) or metastatic pancreatic adenocarcinoma: a retrospective analysis

BackgroundMost patients with ductal pancreatic adenocarcinoma are diagnosed with locally advanced (unresectable) or metastatic disease. The aim of this study was to evaluate the prognostic significance of DNA ploidy in relation with established clinical and laboratory variables in such patients.MethodsTwo hundred and twenty six patients were studied retrospectively. Twenty two potential prognostic variables (demographics, clinical parameters, biochemical markers, treatment modality) were examined.ResultsMean survival time was 38.41 weeks (95% c.i.: 33.17–43.65), median survival 27.00 weeks (95% c.i.: 23.18–30.82). On multivariate analysis, 10 factors had an independent effect on survival: performance status, local extension of tumor, distant metastases, ploidy score, anemia under epoetin therapy, weight loss, pain, steatorrhoea, CEA, and palliative surgery and chemotherapy. Patients managed with palliative surgery and chemotherapy had 6.7 times lower probability of death in comparison with patients without any treatment. Patients with ploidy score > 3.6 had 5.0 times higher probability of death in comparison with patients with ploidy score < 2.2 and these with ploidy score 2.2–3.6 had 6.3 times higher probability of death in comparison with patients with ploidy score < 2.2.ConclusionAccording to the significance of the examined factor, survival was improved mainly by the combination of surgery and chemotherapy, and the presence of low DNA ploidy score.

Leucovorin + 5-fluorouracil plus dipyridamole in leucovorin + 5-fluorouracil-pretreated patients with advanced colorectal cancer: a pilot study of three different dipyridamole regimens.

Dipyridamole, an inhibitor of nucleoside transport, increases the activity of 5-fluorouracil in a dose-dependent manner. The purpose of the present study was to determine whether dipyridamole with 5-fluorouracil and leucovorin gave an improved therapeutic outcome. Sixty patients entered in the present pilot study had previously received 5-fluorouracil (450 mg/m2) and leucovorin (100 mg/m2), every week, and relapsed during this treatment, which ended at least 6 weeks prior to study entry. Dipyridamole was administered at three different dosing schedules (DS) and methods of administration in three groups of patients. DS I: dipyridamole, 30 mg/m2 in normal saline solution, in 90 min iv infusion, followed by leucovorin, 100 mg/m2 iv push, followed by 5-fluorouracil, 450 mg/m2 in normal saline solution, in 60 min iv infusion, dipyridamole tablets (75 mg) every 12 hrs, continuously during the time of chemotherapy. DS II: dipyridamole, 50 mg/m2 in normal saline solution, in 90 min iv infusion, and the rest was the same as DS I. DS III: without oral dipyridamole, patients received dipyridamole (50 mg/m2) iv in the same manner as in DS I and II. Treatment was continued until tumor progression or unacceptable toxicity. All patients (n = 60) entered in the present study were assessable for response and toxicity. No complete response was observed. No patient at DS I responded, whereas 2 patients at DS II and 3 at DS III had a partial response (P <0.1). Stable disease was found with DS I (n = 1), DS II (n = 8) and DS III (n = 9) (P <0.01). More patients progressed at DS I (n = 19) than at DS II (n = 10) and DS III (n = 8) (P <0.0007). The median duration of response was 11 weeks (range, 8-16). Time to progression was 17 weeks for DS I, 15 weeks (range, 10-19) for DS II, and 14 weeks (range, 11-21) for DS III (P = 0.43). Median survival did not differ significantly between DS I (29 weeks; range, 14-48), DS II (31.5 weeks; range, 17-63) and DS III (36 weeks; range, 16-58) (P = 0.2). Neutropenia was most severe with DS I (grade 2, P <0.01) and DS II (grade 1, P <0.05) and nausea/vomiting with DS I (grade 0, P < 0.0005, grade 1, P <0.0002, grade 2, P <0.02) and DS III (grade 3, P <0.0009). Diarrhea was most severe in DS II (grade 3, P <0.005). Mucositis was increased in DS II (grade 0, P <0.008), anorexia in DS II (grade 0, P <0.032) and fatigue in DS I (grade 0, P <0.003). More patients in DS I than with the other two DS experienced headache (P <0.044). According to the response achieved at DS III (15% partial response and 45% stable disease) and the toxicity which was well tolerated mainly in this DS (except for nausea and vomiting grade 3, P <0.009), it can be stated that DS III is the appropriate dose and the simplest schedule of administration (administration of dipyridamole during therapy only). In conclusion, it appears that dipyridamole might still have a role in enhancing the clinical activity of drugs involved in the inhibition of the thymidylate synthetase biochemical pathway and its activity in combination with these agents (5-fluorouracil + leucovorin) as frontline treatment should therefore be explored in future phase II studies.