Steve Hazell

Development of synchronous VHL syndrome tumors reveals contingencies and constraints to tumor evolution

BackgroundGenomic analysis of multi-focal renal cell carcinomas from an individual with a germline VHL mutation offers a unique opportunity to study tumor evolution.ResultsWe perform whole exome sequencing on four clear cell renal cell carcinomas removed from both kidneys of a patient with a germline VHL mutation. We report that tumors arising in this context are clonally independent and harbour distinct secondary events exemplified by loss of chromosome 3p, despite an identical genetic background and tissue microenvironment. We propose that divergent mutational and copy number anomalies are contingent upon the nature of 3p loss of heterozygosity occurring early in tumorigenesis. However, despite distinct 3p events, genomic, proteomic and immunohistochemical analyses reveal evidence for convergence upon the PI3K-AKT-mTOR signaling pathway. Four germline tumors in this young patient, and in a second, older patient with VHL syndrome demonstrate minimal intra-tumor heterogeneity and mutational burden, and evaluable tumors appear to follow a linear evolutionary route, compared to tumors from patients with sporadic clear cell renal cell carcinoma.ConclusionsIn tumors developing from a germline VHL mutation, the evolutionary principles of contingency and convergence in tumor development are complementary. In this small set of patients with early stage VHL-associated tumors, there is reduced mutation burden and limited evidence of intra-tumor heterogeneity.

Tracking Cancer Evolution Reveals Constrained Routes to Metastases: TRACERx Renal

Summary Clear-cell renal cell carcinoma (ccRCC) exhibits a broad range of metastatic phenotypes that have not been systematically studied to date. Here, we analyzed 575 primary and 335 metastatic biopsies across 100 patients with metastatic ccRCC, including two cases sampledat post-mortem. Metastatic competence was afforded by chromosome complexity, and we identify 9p loss as a highly selected event driving metastasis and ccRCC-related mortality (p = 0.0014). Distinct patterns of metastatic dissemination were observed, including rapid progression to multiple tissue sites seeded by primary tumors of monoclonal structure. By contrast, we observed attenuated progression in cases characterized by high primary tumor heterogeneity, with metastatic competence acquired gradually and initial progression to solitary metastasis. Finally, we observed early divergence of primitive ancestral clones and protracted latency of up to two decades as a feature of pancreatic metastases.

Deterministic Evolutionary Trajectories Influence Primary Tumor Growth: TRACERx Renal

Summary The evolutionary features of clear-cell renal cell carcinoma (ccRCC) have not been systematically studied to date. We analyzed 1,206 primary tumor regions from 101 patients recruited into the multi-center prospective study, TRACERx Renal. We observe up to 30 driver events per tumor and show that subclonal diversification is associated with known prognostic parameters. By resolving the patterns of driver event ordering, co-occurrence, and mutual exclusivity at clone level, we show the deterministic nature of clonal evolution. ccRCC can be grouped into seven evolutionary subtypes, ranging from tumors characterized by early fixation of multiple mutational and copy number drivers and rapid metastases to highly branched tumors with >10 subclonal drivers and extensive parallel evolution associated with attenuated progression. We identify genetic diversity and chromosomal complexity as determinants of patient outcome. Our insights reconcile the variable clinical behavior of ccRCC and suggest evolutionary potential as a biomarker for both intervention and surveillance.

Timing the Landmark Events in the Evolution of Clear Cell Renal Cell Cancer: TRACERx Renal

Summary Clear cell renal cell carcinoma (ccRCC) is characterized by near-universal loss of the short arm of chromosome 3, deleting several tumor suppressor genes. We analyzed whole genomes from 95 biopsies across 33 patients with clear cell renal cell carcinoma. We find hotspots of point mutations in the 5′ UTR of TERT, targeting a MYC-MAX-MAD1 repressor associated with telomere lengthening. The most common structural abnormality generates simultaneous 3p loss and 5q gain (36% patients), typically through chromothripsis. This event occurs in childhood or adolescence, generally as the initiating event that precedes emergence of the tumor’s most recent common ancestor by years to decades. Similar genomic changes drive inherited ccRCC. Modeling differences in age incidence between inherited and sporadic cancers suggests that the number of cells with 3p loss capable of initiating sporadic tumors is no more than a few hundred. Early development of ccRCC follows well-defined evolutionary trajectories, offering opportunity for early intervention.

Sarcomatoid carcinoma of the prostate: ERG fluorescence in-situ hybridization confirms epithelial origin†

mutations), with a read depth of 1220. The discovery of somatic mutations associated with particular lesions and clinical phenotypes, such as Ollier disease, has improved our understanding of the pathogenesis of disease. For example, somatic mutations in IDH1 and IDH2 occur in gliomas and acute myeloid leukaemia (AML), and the observation that some of these patients also develop multiple enchondromas led to the discovery that IDH1/2 mutations also occur in conventional central and periosteal cartilaginous neoplasms, with a frequency of 56%. In view of the occasional occurrence of SCSTs in individuals with Ollier disease, and our previous finding of an IDH1 mutation in an ovarian fibroma in such a patient, we screened a cohort of ovarian SCSTs for IDH1 and IDH2 mutations. However, unlike the association of IDH mutations with Ollier disease and sporadic cartilaginous lesions, gliomas and AML, no mutations in IDH1 or IDH2 were detected in our cohort of SCSTs. Although we only analysed the DNA from one block it is unlikely that tumour heterogeneity accounts for the failure to detect the mutations, as these genetic variants appear to be ‘driver mutations’ in other tumours in which these mutations are detected. Ovarian SCSTs account for approximately 5% of ovarian neoplasms and 7% of malignancies. At a molecular level, SCSTs are a heterogeneous group of neoplasms that has yet to be characterized fully. However, there have been some recent significant developments in our understanding of the pathogenesis of SCSTs, namely that FOXL2 mutations occur in more than 95% of adult granulosa cell tumours but not in other SCSTs, and that Sertoli–Leydig cell tumours harbour DICER1 missense mutations. Targeted NGS is a technology which is highly sensitive and also a timeand cost-efficient approach to screen for known mutations. However, a more comprehensive NGS approach using exome or whole-genome sequencing is more likely to accelerate our understanding of the pathogenesis of ovarian SCSTs.

Preoperative imaging in patients undergoing trachelectomy for cervical cancer: Validation of a combined T2- and diffusion-weighted endovaginal MRI technique at 3.0 T

Aim The aim of this study is to validate high-resolution endovaginal T2- and diffusion-weighted MRI measurements (tumour size, volume and length of uninvolved cervical canal) against histology in patients undergoing trachelectomy. Patients/interventions 55 consecutive patients 25–44 years with cervical cancer being considered for trachelectomy were prospectively assessed with endovaginal T2-W and diffusion-weighted MRI. Two independent observers blinded to histology recorded maximum tumour dimension, volume and distance from the superior aspect of the tumour to the internal os. Following trachelectomy, pathologist-outlined tumour sections were photographed with a set scale and similar measurements were recorded. Results Fifteen of 45 patients subsequently treated with fertility-sparing surgery had residual tumour (median histological volume: 0.28 cm3, IQR = 0.14–1.06 cm3). Sensitivity, specificity, positive and negative predictive values for detecting tumour: Observer1: 86.7%, 80.0%, 68.4%, and 92.3%, respectively; Observer2: 86.7%, 90.0%, 81.0%, and 93.1%, respectively. Size and volume correlated between observers (r = 0.96, 0.84, respectively, p < 0.0001). Size correlated between each observer and histology (observer 1 r = 0.91, p < 0.0001; observer 2 r = 0.93, p < 0.0001), volume did not (observer 1: r = 0.08, p = 0.6; observer 2: r = 0.21, p = 0.16); however, differences between observer measurements and histology were not significant (size p = 0.09, volume p = 0.15). Differences between MRI and histology estimates of endocervical canal length were not significant (p = 0.1 both observers). Conclusion In subcentimetre cervical cancers, endovaginal MRI correlates with pathology and is invaluable in assessing patients for fertility-sparing surgery.

Melanoma with rhabdomyosarcomatous differentiation: two further cases of a rare pathologic pitfall.

We describe 2 new cases of malignant melanoma with divergent rhabdomyoblastic differentiation occurring in adult patients. The patients were women aged 67 and 51 years with primary cutaneous and uterine cervical melanoma, respectively. Rhabdomyoblastic differentiation in melanoma is very rare in adult patients, and to our knowledge, only 7 such cases have been described in the world literature, of which only 4 have conclusive documentation of the presence of rhabdomyoblastic differentiation. We present the fifth and sixth cases of adult melanomas with conclusive divergent rhabdomyoblastic differentiation, including the first noncutaneous (cervical) case; we also review the literature and highlight the potential for underrecognition of this phenomenon.

Rhabdomyosarcoma with Pseudolipoblasts Arising in Ovarian Carcinosarcoma: A Distinctive Postchemotherapy Morphologic Variant Mimicking Pleomorphic Liposarcoma

We describe a case of ovarian carcinosarcoma occurring in a 60-year-old female. The neoplasm was excised after neoadjuvant chemotherapy and contained a predominant heterologous pleomorphic rhabdomyosarcomatous component in which there were numerous multivacuolated rhabdomyoblasts that strongly mimicked lipoblasts. The clear cell variant of rhabdomyosarcoma is rarely documented, but this case shows a highly unusual finding in which the rhabdomyoblasts show the prominent multivacuolation with nuclear indentation characteristic of and indistinguishable from pleomorphic lipoblasts. This appears to represent a posttreatment phenomenon. As this finding might conceivably occur in other rhabdomyosarcomas after chemotherapy, we highlight the potential for diagnostic confusion with pleomorphic liposarcoma, which is usually diagnosed by morphology so that immunohistochemistry for muscle markers might not be performed.

Indolent peritoneal mesothelioma: PI3K-mTOR inhibitors as a novel therapeutic strategy

Peritoneal mesothelioma (MPeM) is a scarce abdominal-pelvic malignancy that presents with non-specific features and exhibits a wide clinical spectrum from indolent to aggressive disease. Due to it being a rare entity, there is a lack of understanding of its molecular drivers. Most treatment data are from limited small studies or extrapolated from pleural mesothelioma. Standard treatment includes curative surgery or pemetrexed-platinum palliative chemotherapy. To date, the use of novel targeted agents has been disappointing. Described is the management of two young women with papillary peritoneal mesothelioma with widespread recurrence having received platinum-pemetrexed chemotherapy. Both patients obtained symptomatic and disease benefit with apitolisib, a dual phosphoinositide 3-kinase-mammalian target of rapamycin (PI3K-mTOR) inhibitor for subsequent relapses, with one patient having a partial response for almost 3 years. Both are alive and well 10–13 years from diagnosis. Conclusion These case presentations highlight a subgroup of rare MPeM that behave indolently that is compatible with long-term survival. This series identifies the use of targeted therapies with PI3K-mTOR-based inhibitors as a novel approach, warranting further clinical assessment. Development of prognostic biomarkers is essential to aid identify tumour aggressiveness, help stratify patients and facilitate treatment decisions.