Spatial patterns of tumour growth impact clonal diversification in a computational model and the TRACERx Renal study.

Genetic intra-tumour heterogeneity fuels clonal evolution, but our understanding of clinically relevant clonal dynamics remain limited. We investigated spatial and temporal features of clonal diversification in clear cell renal cell carcinoma through a combination of modelling and real tumour analysis. We observe that the mode of tumour growth, surface or volume, impacts the extent of subclonal diversification, enabling interpretation of clonal diversity in patient tumours. Specific patterns of proliferation and necrosis explain clonal expansion and emergence of parallel evolution and microdiversity in tumours. In silico time-course studies reveal the appearance of budding structures before detectable subclonal diversification. Intriguingly, we observe radiological evidence of budding structures in early-stage clear cell renal cell carcinoma, indicating that future clonal evolution may be predictable from imaging. Our findings offer a window into the temporal and spatial features of clinically relevant clonal evolution.

Determinants of anti-PD-1 response and resistance in clear cell renal cell carcinoma.

ADAPTeR is a prospective, phase II study of nivolumab (anti-PD-1) in 15 treatment-naive patients (115 multiregion tumor samples) with metastatic clear cell renal cell carcinoma (ccRCC) aiming to understand the mechanism underpinning therapeutic response. Genomic analyses show no correlation between tumor molecular features and response, whereas ccRCC-specific human endogenous retrovirus expression indirectly correlates with clinical response. T cell receptor (TCR) analysis reveals a significantly higher number of expanded TCR clones pre-treatment in responders suggesting pre-existing immunity. Maintenance of highly similar clusters of TCRs post-treatment predict response, suggesting ongoing antigen engagement and survival of families of T cells likely recognizing the same antigens. In responders, nivolumab-bound CD8+ T cells are expanded and express GZMK/B. Our data suggest nivolumab drives both maintenance and replacement of previously expanded T cell clones, but only maintenance correlates with response. We hypothesize that maintenance and boosting of a pre-existing response is a key element of anti-PD-1 mode of action.

Selection of metastasis competent subclones in the tumour interior.

The genetic evolutionary features of solid tumour growth are becoming increasingly well described, but the spatial and physical nature of subclonal growth remains unclear. Here, we utilize 102 macroscopic whole-tumour images from clear cell renal cell carcinoma patients, with matched genetic and phenotypic data from 756 biopsies. Utilizing a digital image processing pipeline, a renal pathologist marked the boundaries between tumour and normal tissue and extracted positions of boundary line and biopsy regions to X and Y coordinates. We then integrated coordinates with genomic data to map exact spatial subclone locations, revealing how genetically distinct subclones grow and evolve spatially. We observed a phenotype of advanced and more aggressive subclonal growth in the tumour centre, characterized by an elevated burden of somatic copy number alterations and higher necrosis, proliferation rate and Fuhrman grade. Moreover, we found that metastasizing subclones preferentially originate from the tumour centre. Collectively, these observations suggest a model of accelerated evolution in the tumour interior, with harsh hypoxic environmental conditions leading to a greater opportunity for driver somatic copy number alterations to arise and expand due to selective advantage. Tumour subclone growth is predominantly spatially contiguous in nature. We found only two cases of subclone dispersal, one of which was associated with metastasis. The largest subclones spatially were dominated by driver somatic copy number alterations, suggesting that a large selective advantage can be conferred to subclones upon acquisition of these alterations. In conclusion, spatial dynamics is strongly associated with genomic alterations and plays an important role in tumour evolution.

Standard and Hypofractionated Dose Escalation to Intraprostatic Tumor Nodules in Localized Prostate Cancer: Efficacy and Toxicity in the DELINEATE Trial.

PURPOSE: To report a planned analysis of the efficacy and toxicity of dose escalation to the intraprostatic dominant nodule identified on multiparametric magnetic resonance imaging using standard and hypofractionated external beam radiation therapy. METHODS AND MATERIALS: DELINEATE is a single centre prospective phase 2 multicohort study including standard (cohort A: 74 Gy in 37 fractions) and moderately hypofractionated (cohort B: 60 Gy in 20 fractions) prostate image guided intensity modulated radiation therapy in patients with National Comprehensive Cancer Network intermediate- and high-risk disease. Patients received an integrated boost of 82 Gy (cohort A) and 67 Gy (cohort B) to lesions visible on multiparametric magnetic resonance imaging. Fifty-five patients were treated in cohort A, and 158 patients were treated in cohort B; the first 50 sequentially treated patients in cohort B were included in this planned analysis. The primary endpoint was late Radiation Therapy Oncology Group rectal toxicity at 1 year. Secondary endpoints included acute and late toxicity measured with clinician- and patient-reported outcomes at other time points and biochemical relapse-free survival for cohort A. Median follow-up was 74.5 months for cohort A and 52.0 months for cohort B. RESULTS: In cohorts A and B, 27% and 40% of patients, respectively, were classified as having National Comprehensive Cancer Network high-risk disease. The cumulative 1-year incidence of Radiation Therapy Oncology Group grade 2 or worse rectal and urinary toxicity was 3.6% and 0% in cohort A and 8% and 10% in cohort B, respectively. There was no reported late grade 3 rectal toxicity in either cohort. Within cohort A, 4 of 55 (7%) patients had biochemical relapse. CONCLUSIONS: Delivery of a simultaneous integrated boost to intraprostatic dominant nodules is feasible in prostate radiation therapy using standard and moderately hypofractionated regimens, with rectal and genitourinary toxicity comparable to contemporary series without an intraprostatic boost.

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

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.

Deterministic Evolutionary Trajectories Influence Primary Tumor Growth: TRACERx Renal.

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.

Tracking Cancer Evolution Reveals Constrained Routes to Metastases: TRACERx Renal.

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.

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.

Separation of type and grade in cervical tumours using non-mono-exponential models of diffusion-weighted MRI.

OBJECTIVES: Assessment of empirical diffusion-weighted MRI (DW-MRI) models in cervical tumours to investigate whether fitted parameters distinguish between types and grades of tumours. METHODS: Forty-two patients (24 squamous cell carcinomas, 14 well/moderately differentiated, 10 poorly differentiated; 15 adenocarcinomas, 13 well/moderately differentiated, two poorly differentiated; three rare types) were imaged at 3 T using nine b-values (0 to 800 s mm-2). Mono-exponential, stretched exponential, kurtosis, statistical, and bi-exponential models were fitted. Model preference was assessed using Bayesian Information Criterion analysis. Differences in fitted parameters between tumour types/grades and correlation between fitted parameters were assessed using two-way analysis of variance and Pearson's linear correlation coefficient, respectively. RESULTS: Non-mono-exponential models were preferred by 83 % of tumours with bi-exponential and stretched exponential models preferred by the largest numbers of tumours. Apparent diffusion coefficient (ADC) and diffusion coefficients from non-mono-exponential models were significantly lower in poorly differentiated tumours than well/moderately differentiated tumours. α (stretched exponential), K (kurtosis), f and D* (bi-exponential) were significantly different between tumour types. Strong correlation was observed between ADC and diffusion coefficients from other models. CONCLUSIONS: Non-mono-exponential models were preferred to the mono-exponential model in DW-MRI data from cervical tumours. Parameters of non-mono-exponential models showed significant differences between types and grades of tumours. KEY POINTS: • Non-mono-exponential DW-MRI models are preferred in the majority of cervical tumours. • Poorly differentiated cervical tumours exhibit lower diffusion coefficients than well/moderately differentiated tumours. • Non-mono-exponential model parameters α, K, f, and D* differ between tumour types. • Micro-structural features are likely to affect parameters in non-mono-exponential models differently.

Malignant Ovarian Germ Cell Tumors in Postmenopausal Patients: The Royal Marsden Experience and Literature Review.

BACKGROUND: Ovarian germ cell tumors (OGCT) account for 2-5% of ovarian malignancies, with an annual incidence of 1:100,000, and typically occur in young women and adolescents. The yolk sac tumor (YST) is the second most common subtype of OGCTs and has an aggressive phenotype. Their rarity in postmenopausal women has the potential to cause initial diagnostic uncertainty and lead to delayed or sub-optimal treatment. In this article, we report two cases. The first case is a 67-year-old woman with a pure YST and the second refers to a 59-year-old patient with YST with neuroendocrine differentiation. We also review and summarise the current literature. DISCUSSION: YSTs in older women, either in association with ovarian epithelial tumors or without an identifiable epithelial precursor, are a challenging clinical situation. The disease is aggressive and the outcome remains poor. Thirty-seven cases, including the two reported in this article, have been described in the literature to date. 12/ 37 described patients with malignant OGCTs died within 8 months of diagnosis. CONCLUSION: Ovarian cancer with a YST component in postmenopausal women has an aggressive behaviour and adjuvant platinum-based chemotherapy should be considered.

Exploiting altered patterns of choline kinase-alpha expression on human prostate tissue to prognosticate prostate cancer.

AIMS: Malignant transformation results in overexpression of choline-kinase (CHK) and altered choline metabolism, which is potentially detectable by immunohistochemistry (IHC). We investigated the utility of CHK-alpha (CHKA) IHC as a complement to current diagnostic investigation of prostate cancer by analysing expression patterns in normal (no evidence of malignancy) and malignant human prostate tissue samples. METHODS: As an initial validation, paraffin-embedded prostatectomy specimen blocks with both normal and malignant prostate tissue were analysed for CHKA protein and mRNA expression by western blot and quantitative reverse transcriptase PCR (qRT-PCR), respectively. Subsequently, 100 paraffin-embedded malignant prostate tumour and 25 normal prostate cores were stained for both Ki67 (labelling-index: LI) and CHKA expression. RESULTS: The validity of CHKA-antibody was verified using CHKA-transfected cells and siRNA knockdown. Immunoblotting of tissues showed good resolution of CHKA protein in malignant prostate, verifying use of the antibody for IHC. There was minimal qRT-PCR detectable CHKA mRNA in normal tissue, and conversely high expression in malignant prostate tissues. IHC of normal prostate cores showed mild (intensity) CHKA expression in only 28% (7/25) of samples with no Ki67 expression. In contrast, CHKA was expressed in all malignant prostate cores along with characteristically low proliferation (median 2% Ki67-LI; range 1-17%). Stratification of survival according to CHK intensity showed a trend towards lower progression-free survival with CHK score of 3. CONCLUSIONS: Increased expression of CHKA, detectable by IHC, is seen in malignant lesions. This relatively simple cost-effective technique (IHC) could complement current diagnostic procedures for prostate cancer and, therefore, warrants further investigation.

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

BACKGROUND: Genomic analysis of multi-focal renal cell carcinomas from an individual with a germline VHL mutation offers a unique opportunity to study tumor evolution. RESULTS: We 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. CONCLUSIONS: In 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.

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.

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 cm(3), IQR=0.14-1.06 cm(3)). Sensitivity, specificity, positive and negative predictive values for detecting tumour: Observer 1: 86.7%, 80.0%, 68.4%, and 92.3%, respectively; Observer 2: 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.

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.

Use of [11C]choline PET-CT as a noninvasive method for detecting pelvic lymph node status from prostate cancer and relationship with choline kinase expression.

PURPOSE: To evaluate the accuracy and biological basis for [(11)C]choline-PET-CT in the nodal staging of high risk localized prostate cancer patients. EXPERIMENTAL DESIGN: Twenty-eight patients underwent dynamic [(11)C]choline-PET-CT of the pelvis and lower abdomen prior to extended laparoscopic pelvic lymph node dissection (eLPL). The sensitivity and specificity of [(11)C]choline PET, [(11)C]choline PET-CT, and MRI for nodal detection were calculated. Average and maximal standardized uptake values (SUV(ave), SUV(max)) were compared with choline kinase alpha (CHKα) and Ki67 immunohistochemistry scores. RESULTS: Four hundred and six lymph nodes (LN), in 26 patients, were assessable. Twenty-seven (6.7%) involved pelvic nodes at eLPL were detected in 9 patients. Seventeen of the 27 involved nodes were subcentimeter. The sensitivity and specificity on a per nodal basis were 18.5% and 98.7%, 40.7% and 98.4%, and 51.9% and 98.4% for MRI, [(11)C]choline PET, and [(11)C]choline PET-CT, respectively. Sensitivity was higher for [(11)C]choline PET-CT compared with MRI (P = 0.007). A higher nodal detection rate, including subcentimeter nodes, was seen with [(11)C]choline PET-CT than MRI. Malignant lesions showed CHKα expression in both cytoplasm and nucleus. SUV(ave) and SUV(max) strongly correlated with CHKα staining intensity (r = 0.68, P < 0.0001 and r = 0.63, P = 0.0004, respectively). In contrast, Ki67 expression was generally low in all tumors. CONCLUSION: This study establishes the relationship between [(11)C]choline PET-CT uptake with choline kinase expression in prostate cancer and allows it to be used as a noninvasive means of staging pelvic LNs, being highly specific and more sensitive than MRI, including the detection of subcentimeter disease.