While the genetic evolutionary features of solid tumour growth are becoming increasingly described, the spatial and physical nature of subclonal growth remains unclear. Here we utilise 102 macroscopic whole tumour images from clear cell renal cell carcinoma (ccRCC) patients, with matched genetic and phenotypic data from 756 biopsies. Utilising a digital image processing pipeline the boundaries between tumour and normal tissue were marked by a renal pathologist, and positions of boundary line and biopsy regions were extracted to X- and Y-coordinates. The coordinates were then integrated with genomic data to map exact spatial subclone locations, revealing how genetically distinct subclones grow and evolve spatially. A phenotype of advanced and more aggressive subclonal growth was present in the tumour centre, characterised by an elevated burden of somatic copy number alterations, higher necrosis, proliferation rate and Fuhrman grade. Moreover, metastasising subclones were found to 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 heightened cellular turnover and greater opportunity for driver SCNAs to arise and expand due to selective advantage. Tumour subclone growth was found to be predominantly spatially contiguous in nature, with subclone dispersal a rare event found in two cases, which notably was associated with metastasis. In terms of genetic events, the largest subclones spatially were dominated by driver somatic copy number alterations, suggesting 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.

Background Immune-related diarrhoea/colitis (ir-D/C) is a common adverse event of immune checkpoint inhibitor (ICI) therapy. Guidelines recommend corticosteroid (CS) treatment; however, the average treatment duration for ir-D/C remains poorly defined. Methods All advanced melanoma patients treated with ICI therapy at the Royal Marsden Hospital between 2011 and 2016 were reviewed to identify ir-D/C cases alongside clinical variables. Results 117 any-grade ir-D/C episodes occurred in 109 (21%) patients out of a total of 519 patients treated (ipilimumab=77 episodes, anti-PD1=17 (nivolumab or pembrolizumab), ipilimumab and nivolumab=23 (ipi+nivo)) (seven patients had ir-D/C more than once on different lines of treatment) and >/=grade 3 ir-D/C occurred most frequently (63/519 patients (12%) vs 29/519 (5%) grade 1, and 25/519 (5%) grade 2). Median onset (days) of all-grade ir-D/C after starting ICI therapy was 41 for ipilimumab (IQR 24 to 59, n=77), 91 for anti-PD1 (IQR 46 to 355, n=17) and 45 for ipi+nivo (IQR 24 to 67, n=23). In 71/117 (61%) patients, ir-D/C episodes were treated with CS (17% grade 2; 79% grade 3/4): 54 being steroid-responsive; 17 being steroid-refractory and received additional anti-tumor necrosis factor (TNF) treatment. Median grade 3 ir-D/C CS duration was similar across treatments, averaging 58 days. Median overall CS duration (days) was longer in the grade 3/4 D/C steroid-refractory group (94 vs 45 days). Infection developed in 11/71 (15%) CS recipients and in 6/17 (35%) anti-TNF recipients. In 65/117 (55%) patients, ir-D/C episodes were investigated with flexible sigmoidoscopy. Of these patients, 38/65 (58%) had macroscopic colitis and 12/65 (18%) had microscopic colitis. The steroid-refractory group had more macroscopic changes, 13/17 (76%), than the steroid-responsive group, 22/41 (54%). Conclusion Rates of grade 3 ir-D/C were higher than reported in clinical trials. The 58-day median duration of CS therapy for grade 3 ir-D/C places a significant number of patients at risk of complications. We demonstrate that microscopic colitis is an important subgroup, advocating biopsies in ir-D/C even with macroscopically normal bowel.

Purpose Ipilimumab, a monoclonal antibody inhibiting CLTA-4, is an established treatment in metastatic melanoma, either alone or in combination with nivolumab, and results in immune mediated adverse events, including endocrinopathy. Hypophysitis is one of the most common endocrine abnormalities. An early recognition of hypophysitis may prevent life threatening consequences of hypopituitarism; therefore, biomarkers to predict which patients will develop hypophysitis would have clinical utility. Recent studies suggested that a decline in TSH may serve as an early marker of IH. This study was aimed at assessing the utility of thyroid function tests in predicting development of hypophysitis. Methods A retrospective cohort study was performed for all patients ( n  = 308) treated with ipilimumab either as a monotherapy or in combination with nivolumab for advanced melanoma at the Royal Marsden Hospital from 2010 to 2016. Thyroid function tests, other pituitary function tests and Pituitary MRIs were used to identify those with hypophysitis. Results and conclusions Ipilimumab-induced hypophysitis (IH) was diagnosed in 25 patients (8.15%). A decline in TSH was observed in hypophysitis cohort during the first three cycles but it did not reach statistical significance ( P  = 0.053). A significant fall in FT4 ( P  < 0.001), TSH index ( P  < 0.001) and standardised TSH index ( P  < 0.001) prior to cycles 3 and 4 in hypophysitis cohort was observed. TSH is not useful in predicting development of IH. FT4, TSH index and standardised TSH index may be valuable but a high index of clinical suspicion remains paramount in early detection of hypophysitis.

Although thousands of solid tumors have been sequenced to date, a fundamental under-sampling bias is inherent in current methodologies. This is caused by a tissue sample input of fixed dimensions (e.g., 6 mm biopsy), which becomes grossly under-powered as tumor volume scales. Here, we demonstrate representative sequencing (Rep-Seq) as a new method to achieve unbiased tumor tissue sampling. Rep-Seq uses fixed residual tumor material, which is homogenized and subjected to next-generation sequencing. Analysis of intratumor tumor mutation burden (TMB) variability shows a high level of misclassification using current single-biopsy methods, with 20% of lung and 52% of bladder tumors having at least one biopsy with high TMB but low clonal TMB overall. Misclassification rates by contrast are reduced to 2% (lung) and 4% (bladder) when a more representative sampling methodology is used. Rep-Seq offers an improved sampling protocol for tumor profiling, with significant potential for improved clinical utility and more accurate deconvolution of clonal structure.

The expectation for survival in patients with advanced melanoma now exceeds 50% at 5 years in patients treated with first-line combination ipilimumab and nivolumab, despite this regimen being associated with substantial toxicity. We discuss the latest updates from the Checkmate-067 study, framing the role of this combination in practice today.