MDM4 amplification in atypical lipomatous tumors/well-differentiated liposarcoma: Private event or alternative oncogenic mechanism?

Adipocytic tumors are the most common mesenchymal tumors in soft tissues. Among them, a diagnostic challenge relies in the distinction between lipoma and atypical lipomatous tumor (ALT)/well differentiated liposarcoma (WDLPS), as both entities are often undistinguishable not only from a radiological point of view, but also at the microscopic level and particularly when dealing with small tumor specimen. Thus, detection of recurrent MDM2 amplifications may be the only criteria to discriminate malignant tumors from lipomas. In this study, we report the case of a patient diagnosed with a well differentiated, adipocytic tumor located in the inferior limb and lacking MDM2 amplification, whose diagnosis was reclassified for ALT/WDLPS after identification of an alternative MDM4 amplification by comparative genomic hybridization profiling, whole exome sequencing and fluorescence in situ hybridization (FISH). Screening of a cohort of 37 large, deep-seated, well-differentiated adipocytic tumors previously classified as lipomas using RT-qPCR and FISH failed to detect other cases of MDM4-amplified ALT/WDLPS. This report shows that MDM4 amplification is an exceptional molecular event alternative to MDM2 amplification in ALT/WDLPS. This alteration should be considered and looked for in suspicious adipocytic tumors to optimize their surgical management.

Tumor Growth Rate as a Predictive Marker for Recurrence and Survival After Liver Resection in Patients with Liver Metastases of Uveal Melanoma.

BACKGROUND: Surgical management of liver metastases of uveal melanoma (LMUM) is associated with the best survival rates, especially for patients with a low tumor burden in the liver. The aim was to determine whether the tumor growth rate (TGR0) before liver resection helps predict survival in patients with resectable LMUM. METHODS: This retrospective study included 99 patients with LMUM treated with liver resection between November 2007 and November 2020. TGR0 was expressed as the percentage change in tumor volume over 1 month according to two pretreatment imaging scans. Multivariate Cox analyses identified independent predictors of disease-free survival (DFS) and overall survival (OS). RESULTS: DFS and OS had a statistically significant positive linear relationship (Spearman correlation r = 0.68, p < 0.001). A disease-free interval (DFI) > 24 months and a TGR0 ≤ 50%/month were independent factors associated with better DFS and OS. The 2-component model including TGR0 and DFI had a mean time-dependent area under the curve (AUC) of 0.81 (95% CI, 0.75-0.86) and 0.77 (95% CI, 0.67-0.87), respectively, for predicting DFS and OS. DFI with TGR0 defined three kinetic risk groups that had distinct DFS and OS outcomes (p < 0.001). Cytogenetic alterations at baseline were partially predictive factors of the kinetic risk score based on TGR0 and DFI. DISCUSSION: The assessment of TGR0 improves prognostic stratification by identifying patients at high risk of recurrence and poor survival after liver resection. TGR0 and DFI, reflecting tumor aggressivity, have the potential to be important markers for systemic adjuvant decisions.

Patient Derived Xenografts (PDX) Models as an Avatar to Assess Personalized Therapy Options in Uveal Melanoma: A Feasibility Study.

Uveal melanoma is the most common primary intraocular malignancy in adults. Up to 50% of UM patients develop metastatic disease, usually in the liver. When metastatic, the prognosis is poor, and few treatment options exist. Here, we investigated the feasibility of establishing patient-derived xenografts (PDXs) from a patient's tumor in order to screen for therapies that the patient could benefit from. Samples obtained from 29 primary tumors and liver metastases of uveal melanoma were grafted into SCID mice. PDX models were successfully established for 35% of primary patient tumors and 67% of liver metastases. The tumor take rate was proportional to the risk of metastases. PDXs showed the same morphology, the same GNAQ/11, BAP1, and SF3B1 mutations, and the same chromosome 3 and 8q status as the corresponding patient samples. Six PDX models were challenged with two compounds for 4 weeks. We show that, for 31% of patients with high or intermediate risk of metastasis, the timing to obtain efficacy results on PDX models derived from their primary tumors was compatible with the selection of the therapy to treat the patient after relapse. PDXs could thus be a valid tool ("avatar") to select the best personalized therapy for one third of patients that are most at risk of relapse.

Prognostic Implications of MRI Melanin Quantification and Cytogenetic Abnormalities in Liver Metastases of Uveal Melanoma.

To evaluate the prognostic implications of melanin quantification assessed by magnetic resonance imaging (MRI) with respect to the clinical, pathological, and genetic features of liver metastases of uveal melanoma (LMUM). This single-center retrospective cohort study included 63 patients eligible for margin-free resection of LMUM between 2007 and 2018. Comparative genomic hybridization of resected liver metastases on microarrays was performed for genetic risk classification. Metastases exhibiting monosomy 3 with any type of gain of chromosome 8 (M3/8g) were considered high-genetic-risk. MRI melanin quantification using the mean T1 signal (mT1s) in liver metastases was assessed quantitatively on preoperative imaging examination and compared to that of gross pathological evaluation. The association between MRI melanin quantification and overall survival (OS) was assessed by multivariate analysis using the Cox proportional hazards model. Gross pathological assessment of melanin content and MRI melanin quantification were strongly correlated (r = 0.8, p < 0.001). Independent prognostic factors associated with OS were disease-free interval ≤ 24 months (HR = 3.1; 95% CI, 1.6-6.0; p < 0.001), high-genetic-risk (HR = 2.2; 95% CI, 1.1-4.8; p = 0.04), mT1s > 1.1 (HR = 2.3; 95% CI, 1.2-4.7; p = 0.019), and complete hepatic resection (HR = 0.3; 95% CI, 0.2-0.7; p = 0.004). In patients with high-genetic-risk, mT1s showed a significant association with OS (HR = 3.7; 95% CI, 1.5-9.3; p = 0.006). The median OS was 17.5 months vs. 27 months for >1.1 and ≤1.1 mT1s tumors, respectively (p = 0.003). We showed that the level of pigmentation in M3/8g LMUM identified two subsets that were correlated with distinct clinical outcomes.

Association of Partial Chromosome 3 Deletion in Uveal Melanomas With Metastasis-Free Survival.

Importance: Studies on uveal melanomas (UMs) have demonstrated the prognostic value of 8q gain and monosomy 3, but the prognosis of UMs with partial deletion of chromosome 3 remains to be defined. Objective: To examine the association of partial chromosome 3 deletion in UMs with metastasis-free survival. Design, Setting, and Participants: This retrospective cohort study of 1088 consecutive comparative genomic hybridization arrays performed from May 1, 2006, to July 31, 2015, assessed patients presenting with UMs with and without partial loss of chromosome 3 at a referral center. Data analysis was performed from September 1, 2017, to November 30, 2017. Exposure: Uveal melanoma with or without partial loss of chromosome 3. Main Outcomes and Measures: Metastasis-free survival and overall survival at 60 months. Results: Of the 1088 consecutive comparative genomic hybridization arrays that were performed, 43 UMs (4.0%) in 43 patients (median age, 58 years [range, 12-79 years]; 22 [51%] female) carried partial deletions of chromosome 3. Median follow-up was 66 months (range, 1.2-126.2 months). Metastasis-free survival at 60 months was 33.6% (95% CI, 15.8%-71.4%) for UMs that carried a deletion of the BAP1 (BRCA1 associated protein 1) locus (BAP1del; 24 tumors) and 80.5% (95% CI, 64.8%-100%) for UMs without the loss of the BAP1 locus (BAP1 normal [BAP1nl]; 19 tumors) (log-rank P = .001). Overall survival at 60 months was 64.5% (95% CI, 43.5%-95.8%) in the BAP1del group vs 84.1% (95% CI, 69.0%-100%) in the BAP1nl group (log-rank P < .001). In these 43 cases, metastasis-free survival at 60 months was 100% for UMs without loss of the BAP1 locus or 8q gain, 70.0% (95% CI, 50.5%-96.9%) for UMs that carried 1 of these alterations, and 12.5% (95% CI, 2.1%-73.7%) for those that carried both (log-rank P < .001). Similarly, overall survival at 60 months was 100% for UMs without loss of the BAP1 locus or 8q gain, 80.8% (95% CI, 63.3%-100%) for UMs that carried 1 of these alterations, and 46.7% (95% CI, 23.3%-93.6%) for those that carried both (log-rank P < .001). Conclusions and Relevance: These findings suggest that partial deletion of chromosome 3 encompassing the BAP1 locus is associated with poor prognosis. A cytogenetic classification of UMs could be proposed based on the status of the BAP1 locus instead of the chromosome 3 locus, while also taking chromosome 8q into account.

Comparative Cytogenetic Abnormalities in Paired Choroidal Melanoma Samples Obtained Before and After Proton Beam Irradiation by Transscleral Fine-Needle Aspiration Biopsy and Endoresection.

This study compared the cytogenetic profiles of choroidal melanoma samples retrieved before and after proton beam irradiation. Twenty-four consecutive patients who underwent both fine-needle aspiration biopsy (FNAB) during tantalum clip positioning, and endoresection within three months of irradiation, were retrospectively included. Chromosome alterations were explored by array comparative genomic hybridization. Age at diagnosis was 50 ± 14 years, tumor thickness was 8.6 ± 1.7 mm and tumor diameter was 12.4 ± 2.3 mm. Six FNAB samples were non-contributive (25%), versus one endoresection sample (4%) (p = 0.049). Among 17 cases with paired contributive samples, the profiles of chromosomes 3 and 8 were identical in all cases, except one with partial chromosome 3 loss on the FNAB sample only. Three cases presented additional discordant aberrations on chromosomes other than 3 or 8q. Overall, we identified monosomy 3 in two cases, 8q gain in six cases, and both alterations in three cases. All cases presented GNAQ or GNA11 mutations assessed by a custom next-generation sequencing panel. Among the six cases with non-contributive initial FNAB, three cases presented abnormal 3 or 8q chromosomes detected on the endoresection material. These results demonstrate the higher rentability of endoresection material for cytogenetic analysis compared to FNAB, and provide clinical evidence of tumor heterogeneity in choroidal melanoma.

Iris melanoma relapsing sixteen years after proton-beam therapy: The importance of lifelong follow-up.

PURPOSE: To report a case of locally recurrent spindle-cell iris amelanotic melanoma 16 years after proton-beam therapy. OBSERVATIONS: In 2001, a 45-year-old man presented with an amelanotic iris melanoma, extending from the 5 to 10 o'clock positions on his left eye. High-frequency ultrasonography showed extension of melanoma into the ciliary body. He was initially managed with proton-beam therapy (60 Gy delivered in four fractions over four consecutive days) and underwent ocular and systemic examination at regular intervals over the following years. Local tumor control was achieved, and the patient did not develop metastasis during sixteen consecutive years. In 2017, 16 years after he received proton-beam therapy, the patient developed a focal amelanotic lesion strongly suggestive of a local recurrence of iris melanoma, although it extended from the 1 to 6 o'clock positions. He also presented with treatment-resistant glaucoma with an intraocular pressure (IOP) of 37 mmHg, despite maximal topical IOP-lowering therapy. Since a second irradiation of the anterior segment was contraindicated, the eye was enucleated. Pathological analysis confirmed the diagnosis of iris melanoma and demonstrated iridocorneal angle invasion extending from the initial site to the recurrent tumor location. CONCLUSIONS AND IMPORTANCE: Regular ophthalmological surveillance for life with gonioscopy and high-frequency ultrasonography is recommended in patients with iris melanoma, due to the possibility of delayed local recurrence more than a decade after the initial treatment.

Evolutionary Routes in Metastatic Uveal Melanomas Depend on MBD4 Alterations.

PURPOSE: Uveal melanomas (UM) are genetically simple tumors carrying few copy number alterations (CNA) and a low mutation burden, except in rare MBD4-deficient, hypermutated cases. The genomics of uveal melanoma metastatic progression has not been described. We assessed the genetic heterogeneity of primary and metastatic MBD4-proficient and -deficient uveal melanomas.Experimental Design: We prospectively collected 75 metastatic and 16 primary samples from 25 consecutive uveal melanoma patients, and performed whole-exome sequencing. RESULTS: MBD4-proficient uveal melanomas contained stable genomes at the nucleotide level, acquiring few new single nucleotide variants (SNVs; 16 vs. 13 in metastases and primary tumors, respectively), and no new driver mutation. Five CNAs were recurrently acquired in metastases (losses of 1p, 6q, gains of 1q, 8q, and isodisomy 3). In contrast, MBD4-deficient uveal melanomas carried more than 266 SNVs per sample, with high genetic heterogeneity and TP53, SMARCA4, and GNAS new driver mutations. SNVs in MBD4-deficient contexts were exploited to unveil the timeline of oncogenic events, revealing that metastatic clones arose early after tumor onset. Surprisingly, metastases were not enriched in monosomy 3, a previously defined metastatic risk genomic feature. Monosomy 3 was associated with shorter metastatic-free interval compared with disomy 3 rather than higher rate of relapse. CONCLUSIONS: MBD4-proficient uveal melanomas are stable at the nucleotide level, without new actionable alterations when metastatic. In contrast, MBD4 deficiency is associated with high genetic heterogeneity and acquisition of new driver mutations. Monosomy 3 is associated with time to relapse rather than rate of relapse, thus opening avenues for a new genetic prognostic classification of uveal melanomas.

Does ATRX germline variation predispose to osteosarcoma? Three additional cases of osteosarcoma in two ATR-X syndrome patients.

Osteosarcoma is the most common malignant bone tumor in adolescents and young adults. Most osteosarcomas are sporadic but the risk of osteosarcoma is also increased by germline variants in TP53, RB1 and RECQL4 genes. ATRX germline variations are responsible for the rare genetic disorder X-linked alpha-thalassemia mental retardation (ATR-X) syndrome characterized by severe developmental delay and alpha-thalassemia but no obvious increased risk of cancer. Here we report two children with ATR-X syndrome who developed osteosarcoma. Notably, one of the children developed two osteosarcomas separated by 10 years. Those two cases raise the possibility that ATRX germline variant could be associated with an increased risk of osteosarcoma.