Primary mediastinal large B-cell lymphoma: Outcome of a series of pediatric patients treated with high-dose methotrexate and cytarabine plus anti-CD20.

Between 2007 and 2013, 13 children diagnosed with primary mediastinal large B-cell lymphoma (PMLBL) were treated according to a modified version of AIEOP (Associazione Italiana Ematologia Oncologia Pediatrica) LNH-97 protocol based on high-dose methotrexate, anthracyclines, and addition of anti-CD20. Ten patients achieved a continuous complete remission with front-line therapy. The overall 5-year survival was 91.7%, and event-free survival was 83.9%, with only one patient dying of progressive disease. Despite the few cases, these results demonstrate that this therapy, which includes anti-CD20, given in a multicenter setting, is feasible with acceptable toxicity in children with PMLBL.

Use of minimal disseminated disease and immunity to NPM-ALK antigen to stratify ALK-positive ALCL patients with different prognosis.

We studied the prognostic value of minimal disseminated disease (MDD) and anti-ALK immune response in children with NPM-ALK-positive anaplastic-large cell lymphoma (ALCL) and evaluated their potential for risk stratification. NPM-ALK transcripts were analyzed by RT-PCR in bone marrow/peripheral blood of 128 ALCL patients at diagnosis, whereas ALK antibody titers in plasma were assessed using an immunocytochemical approach. MDD was positive in 59% of patients and 96% showed an anti-ALK response. Using MDD and antibody titer results, patients could be divided into three biological risk groups (bRG) with different prognosis: high risk (bHR): MDD-positive and antibody titer ≤ 1/750, 26/128 (20%); low risk (bLR): MDD negative and antibody titer >1/750, 40/128 (31%); intermediate risk (bIR): all remaining patients, 62/128 (48%). Progression-free survival was 28% (s.e., 9%), 68% (s.e., 6%) and 93% (s.e., 4%) for bHR, bIR and bLR, respectively (P<0.0001). Survival was 71% (s.e., 9%), 83% (s.e., 5%) and 98% (s.e., 2%) for bHR, bIR and bLR (P=0.02). Only bHR and histology other than common type were predictive of higher risk of failure (hazard ratio 4.9 and 2.7, respectively) in multivariate analysis. Stratification of ALCL patients based on MDD and anti-ALK titer should be considered in future ALCL trials to optimize treatment.

Consequences of heat shock protein 72 (Hsp72) expression and activity on stress-induced apoptosis in CD30+ NPM-ALK+ anaplastic large-cell lymphomas.

Understanding the mechanisms that control stress-induced apoptosis is critical to explain how tumours respond to treatment, as cancer cells frequently escape drug toxicity by regulating stress response through heat shock protein (HSP) expression. The overexpression of Hsp72, in particular, results in increased incidence of cell transformation, and correlates with poor prognosis in a wide range of cancers. We have shown that Hsp72 assists folding of oncogenic NPM-ALK kinase in anaplastic large-cell lymphomas (ALCLs), but its role in the maintenance of the malignant phenotype remains uncertain. Therefore, we assessed Hsp72 expression in ALCLs, investigating more in detail the mechanisms that regulate its status and activity. We found that Hsp72 is unique among the HSPs involved in tumourigenesis to be overexpressed in ALK(+) tumours and cell lines and to be induced by stress. Different from other HSPs, Hsp72 prevents cell injury, Bax activation and death by apoptosis in ALK(+) cells, acting both upstream and downstream of mitochondria. Conversely, Hsp72 is underexpressed in ALK(-) ALCL cells, and it is unable to protect cells from apoptosis under stress. Moreover, when Hsp72 expression is reduced following NPM-ALK inhibition, lymphoma cells undergo apoptosis, demonstrating the importance of Hsp72 in regulating ALCL stress response and drug sensitivity.

Prevalence and clinical implications of bone marrow involvement in pediatric anaplastic large cell lymphoma.

Anaplastic large cell lymphoma (ALCL) harbors the reciprocal chromosomal translocation t(2;5)(p23;q35) in approximately 80% of the cases. The genes involved are nucleophosmin (NPM) and anaplastic lymphoma kinase (ALK) and the resulting chimeric NPM-ALK protein is thought to play a key role in the pathogenesis of t(2;5) positive ALCL. Few data on bone marrow (BM) involvement in ALCL have been published and they mostly rely on morphological examination of BM smears. We studied 52 ALCL for NPM-ALK expression by RT-PCR: 47/52 biopsies were positive. In 41 of the 47 cases we obtained the BM at diagnosis and investigated the prevalence of minimal BM infiltration by RT-PCR and real-time PCR. Minimal disseminated disease was positive in 25/41 patients (61%), of whom six had morphologically infiltrated BM. Survival analysis demonstrated a 5-year progression-free survival of 41 +/- 11% for patients with molecularly positive BM vs 100% for patients with negative BM (P = 0.001). These results suggest that minimal BM involvement at diagnosis is a common event in pediatric ALCL and that minimal BM disease monitoring could identify patients at risk of relapse.

Prospective analysis of minimal bone marrow infiltration in pediatric Burkitt's lymphomas by long-distance polymerase chain reaction for t(8;14)(q24;q32).

The chromosomal translocation t(8;14)(q24;q32) represents a characteristic marker for Burkitt's lymphoma (BL). This translocation involves the MYC oncogene on chromosome 8 and the immunoglobulin heavy-chain (IgH) locus on chromosome 14. Since the translocation does not produce a fusion gene, we established a long-distance polymerase chain reaction (LD-PCR) assay that can detect the t(8;14) at the genomic level. The sensitivity of the LD-PCR was 10(-4). We used the LD-PCR assay to prospectively study 78 BL patients and found a specific PCR product in 52 of them. Among the 52 positive patients, we could test both the tumor and the bone marrow (BM) at diagnosis in 33 and determined the prevalence of minimal disseminated disease (MDD) at diagnosis. In 12/33 patients, BM was positive by LD-PCR and in 10 of them we conducted a study of minimal residual disease (MRD). Eight out of 10 children showed a clearance of MRD after one cycle of chemotherapy. The only two patients who did not achieve a negative MRD status died of disease progression. The comparative analysis of sensitivity of BM aspirate, BM biopsy and LD-PCR in t(8;14)-positive patients demonstrated a superiority of the molecular method in the assessment of MDD. The LD-PCR for t(8;14) is an important tool to study minimal BM infiltration at diagnosis and to determine its response kinetics in BL.