Checkpoint inhibitor immunotherapy has revolutionised cancer treatment. However, immunotoxicity due to dysregulated immune control can affect a range of non-cancer tissues causing dermatitis, colitis and endocrinopathies in up to 80% of exposed patients. Peripheral nerve neurotoxicity is rare (<5%) and described as GBS-like or CIDP-like in published case series. Here we present two cases of checkpoint inhibitor associated peripheral neuropathy suggesting this neuritis is a novel pathological entity. Case 1 55-year-old man treated with nivolumab and ipilimumab for renal cell carcinoma developed painful sensory predominant neuropathy after cycle 1. Gait impairment led to discontinuation by cycle 3. NCS revealed axonal loss and conduction slowing but no demyelinating features. He was treated with IVIg without response. Case 2 55-year-old woman with metastatic melanoma was treated with pembrolizumab for 16 months without complication. Within weeks of change to nivolumab she developed painful neuropathic symptoms causing difficulty walking. Neurophysiology was similar to case 1 but she improved to normal with high dose corticosteroids over 4 months. Both sural nerve biopsies showed active large fibre degeneration with diffuse, predominantly T cell inflam- matory infiltrate. No malignant cells. No evidence of a primary demyelinating pathology. This novel inflammatory neuropathy warrants recognition due to alternative treatment response.

The fifth edition of the WHO Blue Book on urological tumours, specifically in the bladder chapter, represents a refinement and update in the classification of bladder tumours building on the aggregate major changes made in previous editions. Progress in the molecular underpinnings of urothelial tumours, particularly with promising stratifiers for more precision‐based treatment approaches, have been made. Special attention has been paid to burning questions in bladder pathology, such as grading, heterogeneous lesions, inverted tumours and substaging. The concept of neuroendocrine tumours will be explained precisely.

The 5th edition of the WHO Classification of Tumours of the Urinary and Male Genital Systems contains relevant revisions and introduces a group of molecularly defined renal tumour subtypes. Herein we present the World Health Organization (WHO) 2022 perspectives on papillary and chromophobe renal cell carcinoma with emphasis on their evolving classification, differential diagnosis, and emerging entities. The WHO 2022 classification eliminated the type 1/2 papillary renal cell carcinoma (pRCC) subcategorization, given the recognition of frequent mixed tumour phenotypes and the existence of entities with a different molecular background within the type 2 pRCC category. Additionally, emerging entities such as biphasic squamoid alveolar RCC, biphasic hyalinising psammomatous RCC, papillary renal neoplasm with reverse polarity, and Warthin‐like pRCC are included as part of the pRCC spectrum, while additional morphological and molecular data are being gathered. In addition to oncocytomas and chromophobe renal cell carcinoma (chRCC), a category of ‘other oncocytic tumours’ with oncocytoma/chRCC‐like features has been introduced, including emerging entities, most with TSC/mTOR pathway alterations (eosinophilic vacuolated tumour and so‐called ‘low‐grade’ oncocytic tumour), deserving additional research. Eosinophilic solid and cystic RCC was accepted as a new and independent tumour entity. Finally, a highly reproducible and clinically relevant universal grading system for chRCC is still missing and is another niche of ongoing investigation. This review discusses these developments and highlights emerging morphological and molecular data relevant for the classification of renal cell carcinoma.

Despite recent advances in the treatment of advanced melanoma using immune checkpoint inhibitors (ICI), 5-year overall survival remains suboptimal. A clear understanding of the potential evolutionary trajectories of melanoma is needed in order to advance treatment and prognostic options. Here we present the Posthumous Evaluation of Advanced Cancer Environment (PEACE) study of advanced melanoma, revealing a diversity of evolutionary pathways to lethality. This interim analysis of our 50-patient cohort comprises 14 ICI-treated patients with a mixture of phenotypic subtypes, including cutaneous, acral, mucosal and melanoma of unknown primary. The sampling regime encompasses a broad range of visceral metastases from various organ sites, with a total of 573 tumor samples (an average of 40 samples per patient). Our data span a variety of modalities, including exomic, transcriptomic, panel sequencing, single cell sequencing, FISH, and radiological data. Clonal phylogenies of patients were diverse in structure: some followed a linear evolutionary trajectory with little to no branching, whereas others followed a branched evolutionary pattern. We also observed various patterns of metastatic seeding, with both monoclonal and polyclonal cases of seeding. In addition, patients treated with chemotherapy showed higher subclonal mutational burden than those without. As with previous literature, we found extensive copy number alterations in these advanced melanomas. In contrast, however, our data also reveal patients with no incidence of WGD, with previous work finding this to be a ubiquitous feature of advanced melanoma. In cases of WGD, the majority of copy number alterations were losses rather than gains. In terms of treatment resistance, we observed loss of heterozygosity in key genes of the antigen presentation pathway (most notably B2M), and little signal of neoantigen loss via immunoediting, indicating that these tumors develop resistance to ICI regardless of neoantigen burden. A further question of interest was the determination of lesion-level factors influencing response to ICI treatment using radiological data. MYC amplification was significantly associated with non-responding lesions, whilst PBX1, a promoter of natural killer cells, was shown to be significantly amplified in responding lesions. Our single-cell data reveal a case of polyclonal seeding at the level of whole-genome doubling. This has implications for sample-level phylogenies that are inferred from copy-number status, indicating that intra-tumor heterogeneity at the level of copy number could confound these trees. We also find a potentially novel driver of melanoma, PHF3. This gene has previously been associated with UV DNA-damage response, however here it was found in a non-sun damaged melanoma to have a clonal, focal 7n copy number gain in an otherwise diploid cancer, with corresponding upregulation of expression. In summary, our study comprises an extensive intra-patient, multi-lesion analysis of advanced melanoma, with important implications in both technical and clinical settings. Citation Format: Alexander Coulton, Irene Lobon, Lavinia Spain, Andrew Rowan, Desiree Shnidrig, Scott Shepherd, Ben Shum, Fiona Byrne, Lewis Au, Kim Edmonds, Ellie Carlyle, Alexandra Renn, Christina Messiou, Charlotte Spencer, Andreas M. Schmidt, Zayd Tippu, Aljosja Rogiers, Max Emmerich, Camille Gerard, Husayn Pallikonda, Cristina Naceur-Lombardelli, Floris Foijer, Hilda van den Bos, René Wardenaar, Diana Spierings, Kate Young, Lisa Pickering, Andrew Furness, Elaine Borg, Miriam Mitchison, David Moore, Mary Falzon, Ian Proctor, Ruby Stewart, Ula Mahadeva, Anna Green, James Larkin, Charles Swanton, Mariam Jamal-Hanjani, Kevin Litchfield, Samra Turajlic. Advanced melanoma exhibits a diversity of evolutionary routes to lethality [abstract]. In: Proceedings of the AACR Special Conference on the Evolutionary Dynamics in Carcinogenesis and Response to Therapy; 2022 Mar 14-17. Philadelphia (PA): AACR; Cancer Res 2022;82(10 Suppl):Abstract nr PR002.

This abstract is being presented as a short talk in the scientific program. A full abstract is available in the Proffered Abstracts section (PR002) of the Conference Proceedings. Citation Format: Alexander Coulton, Irene Lobon, Lavinia Spain, Andrew Rowan, Desiree Shnidrig, Scott Shepherd, Ben Shum, Fiona Byrne, Lewis Au, Kim Edmonds, Ellie Carlyle, Alexandra Renn, Christina Messiou, Charlotte Spencer, Andreas M. Schmidt, Zayd Tippu, Aljosja Rogiers, Max Emmerich, Camille Gerard, Husayn Pallikonda, Cristina Naceur-Lombardelli, Floris Foijer, Hilda van den Bos, René Wardenaar, Diana Spierings, Kate Young, Lisa Pickering, Andrew Furness, Elaine Borg, Miriam Mitchison, David Moore, Mary Falzon, Ian Proctor, Ruby Stewart, Ula Mahadeva, Anna Green, James Larkin, Charles Swanton, Mariam Jamal-Hanjani, Kevin Litchfield, Samra Turajlic. Advanced melanoma exhibits a diversity of evolutionary routes to lethality [abstract]. In: Proceedings of the AACR Special Conference on the Evolutionary Dynamics in Carcinogenesis and Response to Therapy; 2022 Mar 14-17. Philadelphia (PA): AACR; Cancer Res 2022;82(10 Suppl):Abstract nr A012.

Over the last decade, immune checkpoint inhibitors (ICIs) have revolutionised treatment and outcomes for an increasing number of cancer types. By ‘removing the breaks’ they boost the anti-tumour immune response, but their effect is non-specific, and a number of systemic toxicities may arise. Neurological toxicity occurs in 1–14% patients depending upon the ICI regime used (Spain et al., 2016). We have developed a collaborative neurotoxicty service with the Royal Marsden Hospital, and demonstrate that early involve- ment of the neurologist is paramount to ensuring effective and efficient care in this patient group. To date, we have received 24 referrals regarding neurological symptoms in patients receiving ICIs. While half were due to ICI-related neurotoxicity, the remainder were caused by cancer progression (2), neurologi- cal side-effects of either other drugs (3) or systemic immune toxicities (2), or worsening/new ‘conventional’ neurological disorders (5). Therefore in addition to identifying and managing neurological toxicity, the role of the neurologist is to identify where neurological toxicity has not occurred, thus enabling the patient to be treated appropriately, while continuing with potentially life-saving immune therapy. With increasing use of these drugs, more robust understanding of risk, patterns and mechanisms of neurological injury must be established through collaborative, cross-disciplinary work to optimise outcomes in this patient group. rachel.brown@ucl.ac.uk

The 5th edition of the World Health Organisation Blue Book was published recently and includes a comprehensive update on testicular tumours. This builds upon the work of the 4th edition, retaining its structure and main nomenclature, including the use of the term ‘germ cell neoplasia in situ’ (GCNIS) for the pre‐invasive lesion of most germ cell tumours and division from those not derived from GCNIS. While there have been important developments in understanding the molecular underpinnings of testicular cancer, this updated classification paradigm and approach remains rooted in morphology. Nomenclature changes include replacement of the term ‘primitive neuroectodermal tumour’ by ‘embryonic neuroectodermal tumour’ based on the non‐specificity of the former term and to separate these tumours clearly from Ewing sarcoma. Seminoma is placed in a germinoma family of tumours emphasising relation to those tumours at other sites. Criteria for the diagnosis of ‘teratoma with somatic transformation’ have been modified to not include variable field size assessments. The word ‘carcinoid’ has been changed to ‘neuroendocrine tumour’, with most examples in the testis now classified as ‘prepubertal type testicular neuroendocrine tumour’. For sex cord‐stromal tumours, the use of mitotic counts per high‐power field has been changed to per mm2 for malignancy assessments, and the new entities, ‘signet ring stromal tumour’ and ‘myoid gonadal stromal tumour’, are defined. Well‐differentiated papillary mesothelial tumour has now been defined as tumour type with a favourable prognosis. Sertoliform cystadenoma has been removed as an entity from testicular adnexal tumours and placed with Sertoli cell tumours.

Cancer is an evolutionary process that is characterized by the emergence of multiple genetically distinct populations or clones within the primary tumor. Intratumor heterogeneity provides a substrate for the selection of adaptive clones, such as those that lead to metastasis. Comparative molecular studies of primary tumors and metastases have identified distinct genomic features associated with the development of metastases. In this review, we discuss how these insights could inform clinical decision-making and uncover rational antimetastasis treatment strategies.

Abstract Renal cell carcinoma (RCC) occurs in a number of cancer predisposition syndromes, but the genetic architecture of susceptibility to RCC is not well defined. We investigated the frequency of pathogenic and likely pathogenic (P/LP) germline variants in cancer susceptibility genes (CSGs) within a large series of unselected RCC participants. Whole-genome sequencing data on 1336 RCC participants and 5834 controls recruited to the UK 100 000 Genomes Project, a nationwide multicentre study, was analyzed to identify rare P/LP short variants (single nucleotide variants and insertions/deletions ranging from 1 to 50 base pairs) and structural variants in 121 CSGs. Among 1336 RCC participants [mean: 61.3 years (±12 SD), range: 13–88 years; 64% male], 85 participants [6.4%; 95% CI (5.1, 7.8)] had one or more P/LP germline variant in a wider range of CSGs than previously recognized. A further 64 intragenic variants in CSGs previously associated with RCC were classified as a variant of uncertain significance (VUS) (24 ‘hot VUSs’) and were considered to be of potential clinical relevance as further evaluation might results in their reclassification. Most patients with P variants in well-established CSGs known to predispose to renal cell carcinoma (RCC-CSGs) were aged <50 years. Burden test analysis for filtered variants in CSGs demonstrated a significant excess of CHEK2 variants in European RCC participants compared with the healthy European controls (P = 0.0019). Approximately, 6% of the patients with RCC unselected for family history have a germline variant requiring additional follow-up analysis. To improve diagnostic yield, we suggest expanding the panel of RCC-CSGs tested to include CHEK2 and all SDHx subunits and raising the eligibility criteria for age-based testing.

Sequencing of cell-free DNA (cfDNA) in cancer patients' plasma offers a minimally-invasive solution to detect tumor cell genomic alterations to aid real-time clinical decision-making. The reliability of copy number detection decreases at lower cfDNA tumor fractions, limiting utility at earlier stages of the disease. To test a novel strategy for detection of allelic imbalance, we developed a prostate cancer bespoke assay, PCF_SELECT, that includes an innovative sequencing panel covering ∼25 000 high minor allele frequency SNPs and tailored analytical solutions to enable allele-informed evaluation. First, we assessed it on plasma samples from 50 advanced prostate cancer patients. We then confirmed improved detection of genomic alterations in samples with <10% tumor fractions when compared against an independent assay. Finally, we applied PCF_SELECT to serial plasma samples intensively collected from three patients previously characterized as harboring alterations involving DNA repair genes and consequently offered PARP inhibition. We identified more extensive pan-genome allelic imbalance than previously recognized in prostate cancer. We confirmed high sensitivity detection of BRCA2 allelic imbalance with decreasing tumor fractions resultant from treatment and identified complex ATM genomic states that may be incongruent with protein losses. Overall, we present a framework for sensitive detection of allele-specific copy number changes in cfDNA.