Perspectives in Melanoma: meeting report from the Melanoma Bridge (December 3rd-5th, 2020, Italy)

Advances in immune checkpoint therapy and targeted therapy have led to improvement in overall survival for patients with advanced melanoma. Single agent checkpoint PD-1 blockade and combination with BRAF/MEK targeted therapy demonstrated benefit in overall survival (OS). Superior response rates have been demonstrated with combined PD-1/CTLA-4 blockade, with a significant OS benefit compared with single-agent PD-1 blockade. Despite the progress in diagnosis of melanocytic lesions, correct classification of patients, selection of appropriate adjuvant and systemic therapies, and prediction of response to therapy remain real challenges in melanoma. Improved understanding of the tumor microenvironment, tumor immunity and response to therapy has prompted extensive translational and clinical research in melanoma. Development of novel biomarker platforms may help to improve diagnostics and predictive accuracy for selection of patients for specific treatment. There is a growing evidence that genomic and immune features of pre-treatment tumor biopsies may correlate with response in patients with melanoma and other cancers but they have yet to be fully characterized and implemented clinically. Overall, the progress in melanoma therapeutics and translational research will help to optimize treatment regimens to overcome resistance and develop robust biomarkers to guide clinical decision-making. During the Melanoma Bridge meeting (December 3rd–5th, 2020, Italy) we reviewed the currently approved systemic and local therapies for advanced melanoma and discussed novel biomarker strategies and advances in precision medicine

Topo IV is the topoisomerase that knots and unknots sister duplexes during DNA replication

DNA topology plays a crucial role in all living cells. In prokaryotes, negative supercoiling is required to initiate replication and either negative or positive supercoiling assists decatenation. The role of DNA knots, however, remains a mystery. Knots are very harmful for cells if not removed efficiently, but DNA molecules become knotted in vivo. If knots are deleterious, why then does DNA become knotted? Here, we used classical genetics, high-resolution 2D agarose gel electrophoresis and atomic force microscopy to show that topoisomerase IV (Topo IV), one of the two type-II DNA topoisomerases in bacteria, is responsible for the knotting and unknotting of sister duplexes during DNA replication. We propose that when progression of the replication forks is impaired, sister duplexes become loosely intertwined. Under these conditions, Topo IV inadvertently makes the strand passages that lead to the formation of knots and removes them later on to allow their correct segregation

Melanoma central nervous system metastases: current approaches, challenges, and opportunities

Melanoma central nervous system metastases are increasing, and the challenges presented by this patient population remain complex. In December 2015, the Melanoma Research Foundation and the Wistar Institute hosted the First Summit on Melanoma Central Nervous System (CNS) Metastases in Philadelphia, Pennsylvania. Here, we provide a review of the current status of the field of melanoma brain metastasis research; identify key challenges and opportunities for improving the outcomes in patients with melanoma brain metastases; and set a framework to optimize future research in this critical area

Neutrophils in cancer: neutral no more

Neutrophils are indispensable antagonists of microbial infection and facilitators of wound healing. In the cancer setting, a newfound appreciation for neutrophils has come into view. The traditionally held belief that neutrophils are inert bystanders is being challenged by the recent literature. Emerging evidence indicates that tumours manipulate neutrophils, sometimes early in their differentiation process, to create diverse phenotypic and functional polarization states able to alter tumour behaviour. In this Review, we discuss the involvement of neutrophils in cancer initiation and progression, and their potential as clinical biomarkers and therapeutic targets

Acute rhabdomyolysis with severe polymyositis following ipilimumab-nivolumab treatment in a cancer patient with elevated anti-striated muscle antibody

BACKGROUND: Immune checkpoint inhibitors have revolutionized cancer therapy since these drugs target inhibitory pathways on T cells, which result in durable anti-tumor immune responses and significant overall survival for a subset of cancer patients. These drugs can also lead to toxicities, which require additional research to identify mechanisms of toxicities and biomarkers that can help to identify patients who will develop immune-related adverse events. CASE PRESENTATION: We describe the first case, to our knowledge, of a patient with metastatic urothelial carcinoma who developed acute rhabdomyolysis with severe polymyositis after treatment with combination immunotherapy consisting of ipilimumab plus nivolumab (Trial registration: NCT01928394. Registered: 8/21/2013). We found that this patient had an elevated pre-existing anti-striated muscle antibody titer, which was likely exacerbated with the immunotherapy treatment thereby resulting in the presentation of acute rhabdomyolysis and severe polymyositis. CONCLUSIONS: This case suggests that immune-related adverse events may be linked to subclinical autoimmune conditions which highlights the need for additional studies to identify patients who are at risk for toxicities

Phase Ib/II Trial of Ribociclib in Combination with Binimetinib in Patients with NRAS-Mutant Melanoma

Purpose: Enhanced MAPK pathway signaling and cell-cycle checkpoint dysregulation are frequent in NRAS-mutant melanoma and, as such, the regimen of the MEK inhibitor binimetinib and the selective CDK4/6 inhibitor ribociclib is a rational combination. Patients and Methods: This is a phase Ib/II, open-label study of ribociclib þ binimetinib in patients with NRAS-mutant melanoma (NCT01781572). Primary objectives were to estimate the MTD/ recommended phase II dose (RP2D) of the combination (phase Ib) and to characterize combination antitumor activity at the RP2D (phase II). Tumor genomic characterization and pharmacokinetics/ pharmacodynamics were also evaluated. Results: Ten patients (16.4%) experienced dose-limiting toxicities in cycle 1 of phase Ib. Overall response rate in the phase II cohort (n ¼ 41) for the selected RP2D (binimetinib 45 mg twice daily þ ribociclib 200 mg once daily, 21 days on/7 days off) was 19.5% [8/41; 95% confidence interval (CI), 8.8–34.9]. The response rate was 32.5% (13/40; 95% CI, 20.1–48.0) in patients with NRAS mutation with concurrent alterations of CDKN2A, CDK4, or CCND1. Median progression-free survival was 3.7 months (95% CI, 3.5–5.6) and median overall survival was 11.3 months (95% CI, 9.3–14.2) for all patients. Common treatment-related toxicities included creatine phosphokinase elevation, rash, edema, anemia, nausea, diarrhea, and fatigue. Pharmacokinetics and safety were consistent with single-agent data, supporting a lack of drug–drug interaction. Conclusions: Ribociclib þ binimetinib can be safely administered and is clinically active in patients with NRAS-mutant melanoma. Co-mutations of cell-cycle genes may define a population with greater likelihood of treatment benefit

Replication Fork Reversal after Replication–Transcription Collision

Replication fork arrest is a recognized source of genetic instability, and transcription is one of the most prominent causes of replication impediment. We analyze here the requirement for recombination proteins in Escherichia coli when replication–transcription head-on collisions are induced at a specific site by the inversion of a highly expressed ribosomal operon (rrn). RecBC is the only recombination protein required for cell viability under these conditions of increased replication-transcription collisions. In its absence, fork breakage occurs at the site of collision, and the resulting linear DNA is not repaired and is slowly degraded by the RecJ exonuclease. Lethal fork breakage is also observed in cells that lack RecA and RecD, i.e. when both homologous recombination and the potent exonuclease V activity of the RecBCD complex are inactivated, with a slow degradation of the resulting linear DNA by the combined action of the RecBC helicase and the RecJ exonuclease. The sizes of the major linear fragments indicate that DNA degradation is slowed down by the encounter with another rrn operon. The amount of linear DNA decreases nearly two-fold when the Holliday junction resolvase RuvABC is inactivated in recB, as well as in recA recD mutants, indicating that part of the linear DNA is formed by resolution of a Holliday junction. Our results suggest that replication fork reversal occurs after replication–transcription head-on collision, and we propose that it promotes the action of the accessory replicative helicases that dislodge the obstacle

Peripheral blood clinical laboratory variables associated with outcomes following combination nivolumab and ipilimumab immunotherapy in melanoma

Both the combination of nivolumab + ipilimumab and single-agent anti-PD- 1 immunotherapy have demonstrated survival benefit for patients with advanced melanoma. As the combination has a high rate of serious side effects, further analyses in randomized trials of combination versus anti-PD- 1 immunotherapy are needed to understand who benefits most from the combination. Clinical laboratory values that were routinely collected in randomized studies may provide information on the relative benefit of combination immunotherapy. To prioritize which clinical laboratory factors to ultimately explore in these randomized studies, we performed a single-center, retrospective analysis of patients with advanced melanoma who received nivolumab + ipilimumab either as part of a clinical trial (n = 122) or commercial use (n = 87). Baseline routine laboratory values were correlated with overall survival (OS) and overall response rate (ORR). Kaplan–Meier estimation and Cox regression were performed. Median OS was 44.4 months, 95% CI (32.9, Not Reached). A total of 110 patients (53%) responded (CR/PR). Significant independent variables for favorable OS included the following: high relative eosinophils, high relative basophils, low absolute monocytes, low LDH, and a low neutrophil-to- lymphocyte ratio. These newly identified factors, along with those previously reported to be associated with anti-PD- 1 monotherapy outcomes, should be studied in the randomized trials of nivolumab + ipilimumab versus anti-PD- 1 monotherapies to determine whether they help define the patients who benefit most from the combination versus anti-PD- 1 alone

A genome-wide IR-induced RAD51 foci RNAi screen identifies CDC73 involved in chromatin remodeling for DNA repair

To identify new regulators of homologous recombination repair, we carried out a genome-wide short-interfering RNA screen combined with ionizing irradiation using RAD51 foci formation as readout. All candidates were confirmed by independent short-interfering RNAs and validated in secondary assays like recombination repair activity and RPA foci formation. Network analysis of the top modifiers identified gene clusters involved in recombination repair as well as components of the ribosome, the proteasome and the spliceosome, which are known to be required for effective DNA repair. We identified and characterized the RNA polymerase II-associated protein CDC73/Parafibromin as a new player in recombination repair and show that it is critical for genomic stability. CDC73 interacts with components of the SCF/Cullin and INO80/NuA4 chromatin-remodeling complexes to promote Histone ubiquitination. Our findings indicate that CDC73 is involved in local chromatin decondensation at sites of DNA damage to promote DNA repair. This function of CDC73 is related to but independent of its role in transcriptional elongation