Genetics of adnexal tumors: An update

Cutaneous adnexal tumors form a vast heterogeneous group that include frequent entities that are mostly benign, as well as rare tumors that are occasionally malignant. In contrast to cutaneous tumors arising from the interfollicular epidermis that develop as a result of accumulation of UV-induced DNA damage (basal cell carcinoma, squamous cell carcinoma), the oncogenesis of adnexal tumors is related to a broad spectrum of genetic mechanisms (e.g., point mutation, fusion genes, viral integration, etc.). In this setting, specific and recurrent genetic alterations have been progressively reported, and these allow better classification of these entities. For certain of them, immunohistochemical tools are now available, enabling precise integrated histological and molecular diagnosis since certain entities are linked to well-defined alterations. In this context, we aim in this review to summarize the main molecular tools currently available for the classification of adnexal tumors.

Natural history and treatment efficacy in an ambispective case series of NTRK-rearranged mesenchymal tumors

BACKGROUND

Apart for infantile fibrosarcoma (IFS), very little is known about NTRK-rearranged mesenchymal tumors (NMTs). The objective of this study is to describe the distribution, characteristics, natural history, and prognosis of NMT.

PATIENTS AND METHODS

This study was carried out as a translational research program, retrospectively from a cohort of 500 soft tissue sarcoma (STS; excluding IFS) and prospectively both in routine practice and from the RNASARC molecular screening program (N = 188; NCT03375437).

RESULTS

Using RNA-sequencing, NTRK fusion was detected in 16 patient tumors diagnosed as STS: 8 samples of sarcoma with simple genomics (4 NTRK-rearranged spindle cell neoplasm, 3 ALK/ROS wild-type inflammatory myofibroblastic tumor, and 1 quadruple Wild-type gastrointestinal stromal tumor) and 8 samples of sarcomas with complex genomics (dedifferentiated liposarcoma, intimal sarcoma, leiomyosarcoma, undifferentiated pleomorphic sarcoma, high-grade uterine sarcoma, malignant peripheral nerve sheath tumor). Among the eight patients with simple genomics, four were treated with tyrosine receptor kinase inhibitor (TRKi) at different stages of the disease and all benefited from the treatment, including one complete response. Among the eight other patients, six evolved with metastatic spreading and the median metastatic survival was 21.9 months, as classically reported in these tumor types. Two of them received a first-generation TRKi without objective response.

CONCLUSIONS

Our study confirms low frequency and histotype diversity of NTRK fusion in STS. While the activity of TRKi in simple genomics NMT is confirmed, our clinical data encourage subsequent studies focusing on the biological relevance of NTRK fusions in sarcomas with complex genomics together with the efficacy of TRKi in this population.

P14.127 From next generation sequencing and comparative genomic hybridization to personalised medicine for adult primary brain tumors: the profiler trial

BACKGROUND

Personalized anti-tumoral therapies may currently be proposed on the basis of immuno-histochemistry, but also next-generation sequencing and comparative genomic hybridization. ProfiLER trial explored the feasibility, efficacy and the impact of molecular profiling for patients with solid or hematological advanced cancers including brain tumors.

MATERIAL AND METHODS

Patients with primary brain tumors, pre-treated with at least one line of anti-cancer treatment, could be included in this multicentric prospective trial. A molecular profile (next-generation sequencing and comparative genomic hydridization) was established on fresh or archived sample. Weekly molecular tumor board analysed results to propose as far as possible a molecular targeted therapy.

RESULTS

between February 2013 and December 2015, 141 patients with primary brain tumor were enrolled. One hundred five samples were further analyzed as 30 samples were excluded, and 6 are on-going. The rate of screen failure was 16/33 for stereotactic biopsy (49%) versus 11/104 (11%) for removal. The main representative histologic type of tumors were glioblastoma (n=46, 43,8%), low grade glioma (n=26, 24,8%), high grade glioma (n=12, 11,4%) and atypical and anaplastic meningioma (n=8, 7,6%). Median delay between the diagnostic of the primitive tumor and the inclusion in ProfiLER study was 2.7 years (0.2 - 29 years). Median delay between the consent and the results of the multidisciplinary meeting was 2.8 months (1–7.1 months). Forty-three patients (41%) presented at least one “druggable molecular alteration”. The most frequently altered genes were CDKN2A (n=18, 29%), EGFR (n=12, 20%), PDGFRa (n=8, 13%), PTEN (n=8, 13%), CDK4 (n=7, 11%), KIT (n=6, 10%), PIK3CA (n=5, 8%), MDM2 (n=3, 5%). Sixteen patients could not have a proposition of specific treatment due to death before MBT (n=5, 31.3%), lack of available clinical trials (n=9, 56%), or ambiguous results (n=2, 12.5%). Among the 27 patients (26%) for whom a specific therapy has been proposed, only six patients ultimately received a medical targeted therapy (everolimus n=3, erlotinib n=1, ruloxitinib n=1, sorafenib n=1). Four patients discontinued the treatment for toxicity, the 2 others for clinical progression.

CONCLUSION

routine high-throughput sequencing is feasible for brain tumors but delays should be reduced to be able to propose targeted therapies to patients fit enough to benefit from experimental treatment. Macroscopic surgery is the best way to obtain workable samples. Specific panel genes for neurologic tumors should be developed, as well as change of practices concerning exclusion criteria in clinical trials.

JS1.1 Specific genetic alterations of breast tumors lead to Yo paraneoplastic cerebellar syndromes

BACKGROUND

Paraneoplastic cerebellar degenerations with anti-Yo antibodies (Yo-PCD) are rare syndromes associated with ovarian or breast cancers and caused by an auto-immune response against neuronal antigens expressed by tumor cells. We previously demonstrated in Yo-PCD ovarian cancers an association between massive infiltration of ovarian tumors by activated immune effector cells and recurrent gains and/or mutations of onconeural Yo genes (CDR2L and CDR2), suggesting that such genetic alterations in ovarian tumor cells may trigger immune tolerance breakdown and initiation of the auto-immune reaction against Purkinje cells.

MATERIAL AND METHODS

We pursued the characterization of Yo-PCD tumors and specifically studied breast cancer by IHC, FISH, CGH array and RNA sequencing analysis of 17 breast Yo-PCD tumors and by comparing their genetic characteristics with 10 sporadic breast tumors and public databases.

RESULTS

We confirmed that specific genetic alterations were also present in breast cancers associated with Yo-PCD. Moreover, this study provides additional evidence for a role of tumor cell specificities in PCD immunopathology by revealing peculiarities in Yo-PCD breast tumors compared to Yo-PCD ovarian cancer. Indeed, not only the CDR2L Yo gene was amplified in 8/9 breast Yo-PCD cancers but also the Erb2/Her2 gene in 15/16 (both genes are on chromosome 17q). In addition to this original Her2 and Yo antigen amplification confirmed by FISH, we observed an overexpression of these proteins by IHC analysis. These Yo-PCD breast cancers are also all negative for hormone receptors (HR). Thus, Yo-PCD breast tumors seem to belong to the molecularly and clinically distinct class of HR-negative and Her2-enriched breast cancers, which represents less than 10 % of breast cancers in the general population. Transcriptomic analysis confirmed that breast Yo-PCD tumors differ by their expression programs from classical breast cancers molecular subtypes.

CONCLUSION

Understanding the tumor genetic features leading to the immune breakdown and anti-tumor immune response as well as nervous tissue attack remains challenging and seems to be specific according to the tumor subtypes. Herein, our results suggest that, despite sharing common genetic alterations (copy number variations and mutations affecting Yo genes), the Yo-PCD immunopathogenesis of breast and ovarian cancers differ by involving different tumor-specific molecular pathways.

Molecular screening program to select molecular-based recommended therapies for metastatic cancer patients: analysis from the ProfiLER trial

BACKGROUND

Antitumor activity of molecular-targeted agents is guided by the presence of documented genomic alteration in specific histological subtypes. We aim to explore the feasibility, efficacy and therapeutic impact of molecular profiling in routine setting.

PATIENTS AND METHODS

This multicentric prospective study enrolled adult or pediatric patients with solid or hematological advanced cancer previously treated in advanced/metastatic setting and noneligible to curative treatment. Each molecular profile was established on tumor, relapse or biopsies, and reviewed by a molecular tumor board (MTB) to identify molecular-based recommended therapies (MBRT). The main outcome was to assess the incidence rate of genomic mutations in routine setting, across specific histological types. Secondary objectives included a description of patients with actionable alterations and for whom MBRT was initiated, and overall response rate.

RESULTS

Four centers included 2579 patients from February 2013 to February 2017, and the MTB reviewed the molecular profiles achieved for 1980 (76.8%) patients. The most frequently altered genes were CDKN2A (N = 181, 7%), KRAS (N = 177, 7%), PIK3CA (N = 185, 7%), and CCND1 (N = 104, 4%). An MBRT was recommended for 699/2579 patients (27%), and only 163/2579 patients (6%) received at least one MBRT. Out of the 182 lines of MBRT initiated, 23 (13%) partial responses were observed. However, only 0.9% of the whole cohort experienced an objective response.

CONCLUSION

An MBRT was provided for 27% of patients in our study, but only 6% of patients actually received matched therapy with an overall response rate of 0.9%. Molecular screening should not be used at present to guide decision-making in routine clinical practice outside of clinical trials.This trial is registered with ClinicalTrials.gov, number NCT01774409.

Genomic alterations and radioresistance in breast cancer: an analysis of the ProfiLER protocol

BACKGROUND

Breast cancer (BC) patients with comparable prognostic features have heterogeneous outcomes, party related to a possible radiotherapy resistance leading to local-regional recurrences (LRR). The objective of the present study was to identify predictive molecular biomarkers of LRR of BC.

PATIENTS AND METHODS

Genetic profile of 146 BC patients' tumours included in the ProfiLER clinical trial (NC01774409) between 2013 and 2016 were analysed using next-generation-sequencing and comparative-genomic-hybridization tests. Patients and tumour characteristics were retrospectively collected and analysed for association with genomic rearrangements (mutations, amplification, deletions). Only gene alterations observed in >3% of the tumours were selected.

RESULTS

A total of 193 genomic rearrangements were identified, and 16 were observed in >3% of tumours. One was statistically correlated to the risk of local relapse. A median loco-regional progression-free survival (LRPFS) of 23.6 years was reported for PIK3CA mutation carriers (n = 31, 21.2%) versus 9.9 years for PIK3CA wild-type patients (HR 0.27, 95% CI 0.12-0.65, P = 0.002 in univariate analysis). PIK3CA mutation was identified as an independent protective factor on LRR using multivariate analysis (HR 0.29, 95% CI 0.09-0.99, P = 0.047). All other mutations, amplifications or deletions were not found associated with LRPFS.

CONCLUSION

PIK3CA mutation was associated with a lower risk of local relapse in this population of BCs. This is consistent with recent studies suggesting PIK3CA to be part of biological pathways impacting the radiosensitivity.

Response to chemotherapy is not related to chromosome instability in synovial sarcoma

BACKGROUND

Synovial sarcoma (SS) is an aggressive soft-tissue tumor. Despite being considered as a chemosensitive disease, the real impact of perioperative chemotherapy on metastasis-free survival (MFS) is controversial. We have shown that metastatic relapse of SS is strongly associated with genomic complexity. There are no data regarding the potential correlation between genomic complexity and response to chemotherapy.

PATIENTS AND METHODS

The study population included 65 SS patients diagnosed between 1991 and 2013 and with available tissue material. Genomic profiling was carried out by using array-CGH. Forty-five SS out of the 65 patients were treated with neoadjuvant anthracycline/ifosfamide-based chemotherapy. Radiological response was assessed according to RECIST criteria. Histological response was defined by the percentage of recognizable tumor cells on the surgical specimen.

RESULTS

Genomic complexity was significantly associated with MFS. However, there was no statistically significant association between radiological or histological response and genomic complexity.

CONCLUSION

The absence of significant association between response to chemotherapy and genomic complexity suggests that the prognostic value of chromosome instability in SS is independent of response to chemotherapy; mechanisms leading to metastatic relapse of SS are intrinsic to the biology of the tumor and current cytotoxic drugs are only poorly efficient to prevent it.