Background In a phase 1 dose-escalation study, combined inhibition of T-cell checkpoint pathways by nivolumab and ipilimumab demonstrated a high objective response rate, including complete responses in patients with advanced melanoma. Methods In this double-blind study, 142 treatment-naïve patients with metastatic melanoma were randomized 2:1 to receive ipilimumab 3 mg/kg combined with either nivolumab 1 mg/kg or placebo every 3 weeks for 4 doses, followed by nivolumab 3 mg/kg or placebo every 2 weeks until disease progression. The primary endpoint was investigator-assessed objective response in BRAF wild-type patients. Results Among BRAF wild-type patients, the confirmed objective response rate was 61.1% (44/72) in the nivolumab and ipilimumab combination group versus 10.8% (4/37) in the ipilimumab monotherapy group (P<0.001), with complete responses reported in 16 (22.2%) patients in the combination group; none in the ipilimumab group. Median duration of response was not reached with either treatment. Median progression-free survival was not reached for the combination versus 4.4 months for ipilimumab monotherapy (hazard ratio 0.40, 95% CI 0.23 to 0.68; P<0.001). Similar results for response and progression-free survival were also observed in 33 BRAF mutation-positive patients. Grade 3–4 drug-related adverse events were reported in 54.3% of patients receiving the combination compared with 23.9% with ipilimumab monotherapy. Select adverse events of immunological etiology were consistent with phase 1 reports, and most resolved with immune-modulating medication. Conclusion Nivolumab combined with ipilimumab significantly improved objective response rate and progression-free survival compared with ipilimumab monotherapy in treatment-naïve patients with advanced melanoma, and had a manageable safety profile. (ClinicalTrials.gov number, NCT01927419)

Summary Background Previously reported results of phase 2 and phase 3 trials showed a significant improvement in the rate of objective response and progression-free survival with nivolumab (anti-PD-1 antibody) plus ipilimumab (anti-CTLA-4 antibody) vs ipilimumab alone in patients with advanced melanoma. To our knowledge, this is the first report of overall survival data from a randomised, controlled trial evaluating the combination of nivolumab and ipilimumab in advanced melanoma. Methods In this phase 2 trial (CheckMate 069), 142 patients aged ≥18 years with previously untreated, unresectable stage III or IV melanoma, with an Eastern Cooperative Oncology Group performance status of 0 or 1, were randomly assigned 2:1 to receive an intravenous infusion of nivolumab 1 mg/kg plus ipilimumab 3 mg/kg or ipilimumab 3 mg/kg plus placebo, every 3 weeks for 4 doses, followed by nivolumab 3 mg/kg or placebo, respectively, every 2 weeks until disease progression or unacceptable toxicity. Randomisation was done by an interactive voice response system with a permuted block schedule and stratification by BRAF mutation status. The primary endpoint (previously reported) was the rate of investigator-assessed objective response among patients with BRAF V600 wild-type melanoma. Overall survival was an exploratory endpoint. Efficacy analyses were done on the intention-to-treat population, where safety was evaluated in all treated patients. This study is registered with ClinicalTrials.gov, number NCT01927419, and is ongoing but no longer enrolling patients. Findings Between September 16, 2013, and February 6, 2014, we screened 179 patients, randomly allocating 95 patients to nivolumab plus ipilimumab and 47 to ipilimumab (72 [76%] and 37 [79%] patients with BRAF V600 wild-type tumors, respectively). At a median follow-up of 24 months, overall survival rates in all randomized patients were 63·8% (95% CI 53·3–72·6) for nivolumab plus ipilimumab vs 53·6% (95% CI 38·1–66·8) for ipilimumab alone; median overall survival had not been reached in either group (hazard ratio 0·74, 95% CI 0·43–1·26; p=0.26). Grade 3–4 adverse events related to nivolumab plus ipilimumab were reported in 51 [54%] of 94 patients vs 9 [20%] of 46 patients related to ipilimumab alone. The most common treatment-related grade 3–4 adverse events in the combination group were colitis (12 [13%] of 94 patients) and increased alanine aminotransferase (10 [11%]), and for ipilimumab alone, were diarrhoea (five [11%] of 46 patients) and hypophysitis (two [4%]). Serious grade 3–4 adverse events related to nivolumab plus ipilimumab were reported in 34 [36%] of 94 patients vs 4 [9%] of 46 patients related to ipilimumab alone, which included colitis (10 [11%]) and diarrhoea (5 [5%]) in the combination group and diarrhoea (2 [4%]), colitis (1 [2%]), and hypophysitis (1[2%]) in the ipilimumab alone group. Interpretation While follow-up of the patients continues, the results of this analysis suggest that the combination of first-line nivolumab plus ipilimumab may lead to a h...

Given its significant role in the maintenance of genomic stability, histone methylation has been postulated to regulate DNA repair. Histone methylation mediates localization of 53BP1 to a DNA double-strand break (DSB) during homologous recombination repair, but a role in DSB repair by nonhomologous end-joining (NHEJ) has not been defined. By screening for histone methylation after DSB induction by ionizing radiation we found that generation of dimethyl histone H3 lysine 36 (H3K36me2) was the major event.Using a novel human cell system that rapidly generates a single defined DSB in the vast majority of cells, we found that the DNA repair protein Metnase (also SETMAR), which has a SET histone methylase domain, localized to an induced DSB and directly mediated the formation of H3K36me2 near the induced DSB. This dimethylation of H3K36 improved the association of early DNA repair components, including NBS1 and Ku70, with the induced DSB, and enhanced DSB repair. In addition, expression of JHDM1a (an H3K36me2 demethylase) or histone H3 in which K36 was mutated to A36 or R36 to prevent H3K36me2 formation decreased the association of early NHEJ repair components with an induced DSB and decreased DSB repair. Thus, these experiments define a histone methylation event that enhances DNA DSB repair by NHEJ.double-strand break | I-Sce-I | chromatin immunoprecipitation | MRN complex | mathematical modeling H istone methylation is highly regulated by a family of proteins termed histone methylases, which usually share a SET domain (1-3). Histone methylation plays a key role in chromatin remodeling and as such regulates transcription, replication, cell differentiation, genome stability, and apoptosis (1-3). Because of its role in replication and genome stability, histone methylation has been hypothesized to play an important role in DNA repair. DNA double-strand breaks (DSBs) are a cytotoxic form of DNA damage that disrupts many of the cellular functions regulated by histone methylation described above (4-6). Previous reports indicate that histone methylation may be important in DNA DSB repair by homologous recombination: The DSB repair component 53BP1, which is required for proper homologous recombination, is recruited to sites of damage by methylated histone H3 lysine 79 (H3K79) and histone H4 lysine 20 (H4K20) (7-9). However, neither H3K79 nor H4K20 methylation is induced by DNA damage (9), so other histone methylation events at sites of DNA damage have been sought. In addition, a mechanism by which histone methylation might regulate NHEJ DSB repair has yet to be defined. In this study, a survey of histone methylation events after DSB induction revealed that the major immediate H3 methylation event is H3K36me2.Metnase is a DNA DSB repair component that is a fusion of a SET histone methylase domain with a nuclease domain and a domain from a member of the transposase/integrase family (10-14). We showed previously that Metnase enhances nonhomologous end-joining (NHEJ) repair of, and survival after, DNA DSBs, and that its SET dom...

Agents that modulate immune checkpoint proteins, such as cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed death receptor-1 (PD-1), have become a mainstay in cancer treatment. The clinical benefit afforded by immune checkpoint inhibitors can be accompanied by immune-related adverse events (irAE) that affect the skin, gastrointestinal tract, liver, and endocrine system. The types of irAEs associated with immune checkpoint inhibitors are generally consistent across tumor types. Immune-related endocrine events can affect the pituitary, thyroid, and adrenal glands, as well as other downstream target organs. These events are unique when compared with other irAEs because the manifestations are often irreversible. Immune-related endocrine events are typically grade 1/2 in severity and often present with non-specific symptoms, making them difficult to diagnose. The mechanisms underlying immune-related target organ damage in select individuals remain mostly undefined. Management includes close patient monitoring, appropriate laboratory testing for endocrine function, replacement of hormones, and consultation with an endocrinologist when appropriate. An awareness of the symptoms and management of immune-related endocrine events may aid in the safe and appropriate use of immune checkpoint inhibitors in clinical practice.

Because cancer at its origin must acquire permanent genomic mutations, it is by definition a disease of DNA repair. Yet for cancer cells to replicate their DNA and divide, which is the fundamental phenotype of cancer, multiple DNA repair pathways are required. This produces a paradox for the cancer cell, where its origin is at the same time its weakness. To overcome this difficulty, a cancer cell often becomes addicted to DNA repair pathways other than the one that led to its initial mutability. The best example of this is in breast or ovarian cancers with mutated BRCA1 or 2, essential components of a repair pathway for repairing DNA double-strand breaks. Because replicating DNA requires repair of DNA doublestrand breaks, these cancers have become reliant on another DNA repair component, PARP1, for replication fork progression. The inhibition of PARP1 in these cells results in catastrophic doublestrand breaks during replication, and ultimately cell death. The exploitation of the addiction of cancer cells to a DNA repair pathway is based on synthetic lethality and has wide applicability to the treatment of many types of malignancies, including those of hematologic origin. There is a large number of novel compounds in clinical trials that use this mechanism for their antineoplastic activity, making synthetic lethality one of the most important new concepts in recent drug development.

Stromal cell-derived factor-1 (SDF-1/CXCL12) enhances survival of myeloid progenitor cells. The two main questions addressed by us were whether these effects on the progenitors were direct-acting and if SDF-1/CXCL12 enhanced engrafting capability of competitive, repopulating mouse stem cells subjected to short-term ex vivo culture with other growth factors. SDF-1/CXCL12 had survival-enhancing/antiapoptosis effects on human bone marrow (BM) and cord blood (CB) and mouse BM colony-forming units (CFU)-granulocyte macrophage, burst-forming units-erythroid, and CFU-granulocyte-erythroid-macrophage-megakaryocyte with similar dose responses. The survival effects were direct-acting, as assessed on colony formation by single isolated human BM and CB CD34(+++) cells. Effects were mediated through CXCR4 and G(alpha)i proteins. Moreover, SDF-1/CXCL12 greatly enhanced the engrafting capability of mouse long-term, marrow-competitive, repopulating stem cells cultured ex vivo with interleukin-6 and steel factor for 48 h. These results extend information on the survival effects mediated through the SDF-1/CXCL12-CXCR4 axis and may be of relevance for ex vivo expansion and gene-transduction procedures.

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DNA replication produces tangled, or catenated, chromatids, that must be decatenated prior to mitosis or catastrophic genomic damage will occur. Topoisomerase IIα (Topo IIα) is the primary decatenating enzyme. Cells monitor catenation status and activate decatenation checkpoints when decatenation is incomplete, which occurs when Topo IIα is inhibited by chemotherapy agents such as the anthracyclines and epididophyllotoxins. We recently demonstrated that the DNA repair component Metnase (also called SETMAR) enhances Topo IIα-mediated decatenation, and hypothesized that Metnase could mediate resistance to Topo IIα inhibitors. Here we show that Metnase interacts with Topo IIα in breast cancer cells, and that reducing Metnase expression significantly increases metaphase decatenation checkpoint arrest. Repression of Metnase sensitizes breast cancer cells to Topo IIα inhibitors, and directly blocks the inhibitory effect of the anthracycline adriamycin on Topo IIα-mediated decatenation in vitro. Thus, Metnase may mediate resistance to Topo IIα inhibitors, and could be a biomarker for clinical sensitivity to anthracyclines. Metnase could also become an important target for combination chemotherapy with current Topo IIα inhibitors, specifically in anthracycline-resistant breast cancer.