Pre-operative radiotherapy is associated with superior local relapse-free survival in advanced synovial sarcoma.

PURPOSE: Optimization of local therapies in synovial sarcoma (SS) considered unresectable at diagnosis is needed. We evaluated the effects of neoadjuvant versus adjuvant radiation versus surgery only on long-term outcomes. METHODS: Patients with macroscopic SS tumors before chemotherapy (IRS-group-III) in the trials CWS-81, CWS-86, CWS-91, CWS-96, CWS-2002-P and SoTiSaR-registry were analyzed. Local therapies were scheduled after 3 neoadjuvant chemotherapy cycles. RESULTS: Median age of 145 patients was 14.5 years. 106 survivors had median follow-up of 7.0 years. Tumor site was 96 extremities, 19 head-neck, 16 shoulder/hip, 14 trunk. Tumors were < 3 cm in 16, 3-5 cm in 28, 5-10 cm in 55, > 10 cm in 34 patients. In a secondary resection during chemotherapy, R0-status was accomplished in 82, R1 in 30, R2 in 21 (12 missing). Radiotherapy was administered to 115 (R0 61, R1 29, R2 20, missing 5), thereof 57 before and 52 after tumor resection. 23 were treated with surgery only. For all patients, 5 year event-free (EFS) and overall survival (OS) was 68.9% ± 7.6 (95%CI) and 79.1% ± 6.9. To establish independent significance, tumor site, size, surgical results and sequencing of local therapies were analyzed in a Cox regression analysis. Variables associated with EFS and OS are site, size and sequencing of local therapies. Variables associated with local recurrence are site, surgical results and sequencing of local therapies. The only variable associated with suffering metastatic recurrence is tumor size. CONCLUSION: Differences in sequencing of local therapy procedures are independently associated with outcomes. Best local control is achieved when tumors are irradiated pre-operatively and undergo R0 or R1 resection thereafter.

Mutations in ALK signaling pathways conferring resistance to ALK inhibitor treatment lead to collateral vulnerabilities in neuroblastoma cells.

BACKGROUND: Development of resistance to targeted therapies has tempered initial optimism that precision oncology would improve poor outcomes for cancer patients. Resistance mechanisms, however, can also confer new resistance-specific vulnerabilities, termed collateral sensitivities. Here we investigated anaplastic lymphoma kinase (ALK) inhibitor resistance in neuroblastoma, a childhood cancer frequently affected by activating ALK alterations. METHODS: Genome-wide forward genetic CRISPR-Cas9 based screens were performed to identify genes associated with ALK inhibitor resistance in neuroblastoma cell lines. Furthermore, the neuroblastoma cell line NBLW-R was rendered resistant by continuous exposure to ALK inhibitors. Genes identified to be associated with ALK inhibitor resistance were further investigated by generating suitable cell line models. In addition, tumor and liquid biopsy samples of four patients with ALK-mutated neuroblastomas before ALK inhibitor treatment and during tumor progression under treatment were genomically profiled. RESULTS: Both genome-wide CRISPR-Cas9-based screens and preclinical spontaneous ALKi resistance models identified NF1 loss and activating NRASQ61K mutations to confer resistance to chemically diverse ALKi. Moreover, human neuroblastomas recurrently developed de novo loss of NF1 and activating RAS mutations after ALKi treatment, leading to therapy resistance. Pathway-specific perturbations confirmed that NF1 loss and activating RAS mutations lead to RAS-MAPK signaling even in the presence of ALKi. Intriguingly, NF1 loss rendered neuroblastoma cells hypersensitive to MEK inhibition. CONCLUSIONS: Our results provide a clinically relevant mechanistic model of ALKi resistance in neuroblastoma and highlight new clinically actionable collateral sensitivities in resistant cells.

Detection and Validation of Circular DNA Fragments Using Nanopore Sequencing.

Occurrence of extra-chromosomal circular DNA is a phenomenon frequently observed in tumor cells, and the presence of such DNA has been recognized as a marker of adverse outcome across cancer types. We here describe a computational workflow for identification of DNA circles from long-read sequencing data. The workflow is implemented based on the Snakemake workflow management system. Its key step uses a graph-theoretic approach to identify putative circular fragments validated on simulated reads. We then demonstrate robustness of our approach using nanopore sequencing of selectively enriched circular DNA by highly sensitive and specific recovery of plasmids and the mitochondrial genome, which is the only circular DNA in normal human cells. Finally, we show that the workflow facilitates detection of larger circular DNA fragments containing extrachromosomal copies of the MYCN oncogene and the respective breakpoints, which is a potentially useful application in disease monitoring of several cancer types.

The effect of adjuvant therapies on long-term outcome for primary resected synovial sarcoma in a series of mainly children and adolescents.

BACKGROUND: The benefit of adjuvant therapy in synovial sarcoma (SS) treatment is under debate. Long-term follow-up data are missing. METHODS: SS patients treated in the consecutive trials CWS-81, CWS-86, CWS-91, CWS-96, CWS-2002-P, and the SoTiSaR-registry till 2013 were analyzed. RESULTS: Median age of 185 patients was 13.9 years (0.1-56)-with median follow-up of 7.4 years for 163 survivors. Most tumors (76%) were located in extremities. Size was < 3 cm in 58 (31%), 3-5 cm in 59 (32%), 5-10 cm in 42 (23%), and > 10 cm in 13 (7%) (13 missing). In 84 (45%) tumors, first excision was complete (R0 corresponding to IRS-I-group) and in 101 (55%) marginal (R1 corresponding to IRS-II-group). In a subsequent surgical intervention during chemotherapy, R0-status was accomplished in 23 additional IRS-II-group patients with secondary surgery. Radiotherapy was administered to 135 (73%), thereof 62 with R0-status and 67 R1-status (6 missing information). Adjuvant chemotherapy was administered to all but six patients. 5-year event-free (EFS) and overall survival (OS) was 82.9% ± 5.7 (95%CI) and 92.5% ± 3.9. Local and metastatic relapse-free survival was 91.3% ± 4.3 and 92.3% ± 4.1 at 5 years, respectively. In the multivariate analysis, tumor size and no chemotherapy were independently associated with EFS. Size and site were associated with OS. In a detailed analysis of local and metastatic events, tumor size was associated with an independent risk for developing metastases. No independent factor for suffering local recurrence could be identified. DISCUSSION: Omission of chemotherapy in a non-stratified way seems not justified. Size governs survival due to high linear association with risk of suffering metastatic recurrence in a granular classification.