Prognostic Role of Minimal Disseminated Disease and NOTCH1/FBXW7 Mutational Status in Children with Lymphoblastic Lymphoma: The AIEOP Experience

NOTCH1/FBXW7 (N/F) mutational status at diagnosis is employed for T-cell lymphoblastic lymphoma (T-LBL) patients’ stratification in the international protocol LBL 2018. Our aim was to validate the prognostic role of Minimal Disseminated Disease (MDD) alone and in combination with N/F mutational status in a large retrospective series of LBL pediatric patients. MDD was analyzed in 132 bone marrow and/or peripheral blood samples by flow cytometry. Mutations in N/F genes were analyzed on 58 T-LBL tumor biopsies. Using the previously established cut-off of 3%, the four-year progression-free survival (PFS) was 57% for stage I–III patients with MDD ≥ 3% versus 80% for patients with MDD inferior to cut-off (p = 0.068). We found a significant worsening in the four-year PFS for nonmutated (51 ± 12%) compared to mutated patients (100%, p = 0.0013). Combining MDD and N/F mutational status in a subgroup of available cases, we found a statistically significant difference in the four-year PFS for different risk groups (p = 0.0012). Overall, our results demonstrate that N/F mutational status has a more relevant prognostic value than MDD at diagnosis. However, the combination of N/F mutations with MDD analysis could identify patients with very aggressive disease, which might benefit from a more intensive treatment.

Brentuximab Vedotin in Combination with Chemotherapy for Pediatric Patients with ALK+ALCL: Results of COG Trial ANHL12P1

Approximately 30% of pediatric patients with ALCL relapse. While brentuximab vendotin has demonstrated excellent activity in ALCL, it has not been used for newly diagnosed patients. Children's Oncology Group trial ANHL12P1 determined the toxicity and efficacy of brentuximab vedotin with chemotherapy in children with newly diagnosed, non-localized, ALK+/CD30+ ALCL. From 2013 to 2017, 68 children with ALK+ ALCL were enrolled and received brentuximab vedotin (Arm BV). All patients received five-day prophase followed by six cycles of chemotherapy at 21-day intervals. Brentuximab vedotin was given on day 1 of each of the six cycles. Of the 67 eligible patients for toxicity evaluation, 66 completed all six cycles of chemotherapy resulting in 399 cycles evaluable. There were no toxic deaths, no cases of progressive multifocal leukoencephalopathy syndrome, and no cases of grade 3 or 4 neuropathy. The two-year EFS is 79.1% (95% CI, 67.2% to 87.1%). The two-year OS is 97.0% (95% CI, 88.1% to 99.2%). Fourteen patients relapsed and were the only events contributing to EFS. 11 of 14 (79%) relapses occurred within ten months of initial diagnosis, with only one patient (1.5%) having relapsed during therapy. Quantitative RT-PCR for NPM-ALK at baseline (minimal disseminated disease) demonstrated prognostic value and impacted 2-year EFS (P=0.0004). Overall, the addition of brentuximab vedotin to standard chemotherapy does not add significant toxicity, nor does it alter the desired interval between cycles. The addition of brentuximab vedotin prevented relapses during therapy and the overall and event-free survival estimates compare favorably with results obtained using conventional chemotherapy.

Towards molecular stratification of pediatric T-cell lymphoblastic lymphomas based on Minimal Disseminated Disease and NOTCH1/FBXW7 mutational status: the French EURO-LB02 experience

While outcome for pediatric T lymphoblastic lymphoma (T-LBL) has improved with Acute Leukemia-type therapy, survival after relapse remains rare. Few prognostic markers have been identified and the value of Minimal Residual Disease (MRD) is less clear than in T-ALL. Mutations of NOTCH1 and/or FBXW7 (N/F) identify good prognosis T-LBL and both MRD and high-level Minimal Disseminated Disease (MDD) are reported to be of poor prognosis. We evaluated MDD status by 8-color flow cytometry (MFC) and/or digital droplet PCR (ddPCR) in 86 French pediatric T-LBL, of which N/F status was known for 65 (61 treated on the Euro-LB02 protocol). Both techniques gave identical results for MDD/MRD values above 0.1%, allowing compilation. While an MDD threshold of 1% had no prognostic significance, the 54% (44/82) of protocol-treated patients with MDD ≥0.1% had a relatively favorable outcome (overall survival/OS; p=0.026). MDD 0.1% status had no prognostic significance in the 68% of patients with N/F mutations, whereas low/negative MDD status (9/61) identified N/F germline patients at a high risk of relapse (5-year OS of 44.4% vs 90% for MDD ≥0.1%, p=0.014; and a 5-year DFS of 50% vs 90.9% respectively, p=0.041). Combining oncogenetic and MDD status allows identification of 85% of patients with an excellent outcome (5-year OS 91.9% and DFS 95%) and 15% of N/F germline/MDD<0.1% patients who clearly require early alternative treatment (5-year OS 44.4%; p<0.0001 and DFS 50%; p=0.0001).

Minimal disseminated disease evaluation and outcome in trilateral retinoblastoma

Trilateral retinoblastoma (TRb) presents a management challenge, since intracranial tumours are seldom times resectable and quickly disseminate. However, there are no risk factors to predict the final outcome in each patient.ObjectiveTo evaluate minimal disseminated disease (MDD) in the bone marrow (BM) and the cerebrospinal fluid (CSF) at diagnosis and during follow-up and reviewing its potential impact in the outcome of patients with TRb.Methods and analysisWe evaluated MDD in five patients with TRb, detecting the mRNA of CRX and/or GD2, in samples from BM and CSF, obtained at diagnosis, follow-up and relapse.ResultsTreatment involved intensive systemic chemotherapy in four patients, one did not receive this treatment and died of progression of the disease. Two patients underwent stem cell rescue. Three patients had leptomeningeal relapse and died. One patient remains disease-free for 84 months. RB1 mutations were identified in the five patients, all of them were null mutations. At diagnosis, one patient had tumour cells in the CSF, and none had the BM involved. Only one case of four presented MDD during follow-up in the CSF, without concomitant detection in the BM. On leptomeningeal relapse, no case had MDD in the BM. In all these cases, cells in the CSF were positive for GD2 and/or CRX.ConclusionCSF dissemination always concluded in the death of the patient, without concomitant systemic dissemination denoting the importance of increasing treatment directed to the CSF compartment. The MDD presence could indicate a forthcoming relapse.