The upcoming 5th edition of the World Health Organization (WHO) Classification of Haematolymphoid Tumours is part of an effort to hierarchically catalogue human cancers arising in various organ systems within a single relational database. This paper summarizes the new WHO classification scheme for myeloid and histiocytic/dendritic neoplasms and provides an overview of the principles and rationale underpinning changes from the prior edition. The definition and diagnosis of disease types continues to be based on multiple clinicopathologic parameters, but with refinement of diagnostic criteria and emphasis on therapeutically and/or prognostically actionable biomarkers. While a genetic basis for defining diseases is sought where possible, the classification strives to keep practical worldwide applicability in perspective. The result is an enhanced, contemporary, evidence-based classification of myeloid and histiocytic/dendritic neoplasms, rooted in molecular biology and an organizational structure that permits future scalability as new discoveries continue to inexorably inform future editions.

We herein present an overview of the upcoming 5th edition of the World Health Organization Classification of Haematolymphoid Tumours focussing on lymphoid neoplasms. Myeloid and histiocytic neoplasms will be presented in a separate accompanying article. Besides listing the entities of the classification, we highlight and explain changes from the revised 4th edition. These include reorganization of entities by a hierarchical system as is adopted throughout the 5th edition of the WHO classification of tumours of all organ systems, modification of nomenclature for some entities, revision of diagnostic criteria or subtypes, deletion of certain entities, and introduction of new entities, as well as inclusion of tumour-like lesions, mesenchymal lesions specific to lymph node and spleen, and germline predisposition syndromes associated with the lymphoid neoplasms.

Key Points Adult patients with ETP-ALL/LBL have poor long-term outcomes. Novel therapies are urgently needed for adult patients with ETP-ALL/LBL.

Elucidation of tumor-DNA virus associations in many cancer types has enhanced our knowledge of fundamental oncogenesis mechanisms and provided a basis for cancer prevention initiatives. RNA-Seq is a novel tool to comprehensively assess such associations. We interrogated RNA-Seq data from 3,775 malignant neoplasms in The Cancer Genome Atlas database for the presence of viral sequences. Viral integration sites were also detected in expressed transcripts using a novel approach. The detection capacity of RNA-Seq was compared to available clinical laboratory data. Human papillomavirus (HPV) transcripts were detected using RNA-Seq analysis in head-and-neck squamous cell carcinoma, uterine endometrioid carcinoma, and squamous cell carcinoma of the lung. Detection of HPV by RNA-Seq correlated with detection by in situ hybridization and immunohistochemistry in squamous cell carcinoma tumors of the head and neck. Hepatitis B virus and Epstein-Barr virus (EBV) were detected using RNA-Seq in hepatocellular carcinoma and gastric carcinoma tumors, respectively. Integration sites of viral genes and oncogenes were detected in cancers harboring HPV or hepatitis B virus but not in EBV-positive gastric carcinoma. Integration sites of expressed viral transcripts frequently involved known coding areas of the host genome. No DNA virus transcripts were detected in acute myeloid leukemia, cutaneous melanoma, low-and high-grade gliomas of the brain, and adenocarcinomas of the breast, colon and rectum, lung, prostate, ovary, kidney, and thyroid. In conclusion, this study provides a large-scale overview of the landscape of DNA viruses in human malignant cancers. While further validation is necessary for specific cancer types, our findings highlight the utility of RNA-Seq in detecting tumor-associated DNA viruses and identifying viral integration sites that may unravel novel mechanisms of cancer pathogenesis.

Background The combination of chemotherapy with a tyrosine kinase inhibitor (TKI) is effective in the treatment of Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL). Ponatinib is a more potent BCR-ABL1 inhibitor and selectively suppresses the resistant T315I clones. We examined the efficacy and safety of combining chemotherapy with ponatinib for patients with Ph+ ALL in this ongoing Phase II prospective trial. Methods Adult patients with newly diagnosed Ph+ ALL and good performance and organ status received 8 cycles of hyper-CVAD alternating with high dose methotrexate/cytarabine every 21 days. Ponatinib was given at 45 mg daily for the first 14 days of cycle 1 then continuously for the subsequent cycles. Patients in complete remission (CR) received maintenance with ponatinib 45 mg daily with vincristine/prednisone monthly for 2 years followed by ponatinib indefinitely. The primary endpoint for this study was the improvement of median event-free survival from 24 to 36 months. The trial was registered on clinicaltrials.gov with the identifier NCT01424982. Results Thirty-seven patients with a median age of 51 years were treated. The overall complete cytogenetic response, major molecular response, and complete molecular response rates were 32/32 (100%), 35/37 (95%), and 29/37 (78%), respectively. By multiparameter flow cytometry, 35 patients (95%) had no detectable minimal residual disease after a median of 3 weeks of therapy. Grade ≥ 3 toxicity included infections during induction (20 patients), increased liver functional tests (14 patients), thrombotic events (3 patients), myocardial infarction (3 patients), hypertension (6 patients), skin rash (8 patients), and pancreatitis (6 patients). Two potentially related deaths from myocardial infarction were observed. Nine patients underwent allogeneic stem cell transplantation. With a median follow up of 26 months, 29 patients (78%) remain alive and in CR. The 2-year event-free and overall survival rates are 81% and 80%, respectively. Conclusion The first results of this ongoing trial indicate that the combination of chemotherapy with ponatinib is highly effective in achieving early sustained remissions in patients with newly diagnosed Ph+ ALL. New strategies, including dosing titration of ponatinib and optimized control of vascular risk factors may further improve outcomes. ARIAD Pharmaceuticals Inc. provided free drug and financial support from the ARIAD Investigator Sponsored Trial program.