SMC complexes differentially compact mitotic chromosomes according to genomic context

Structural maintenance of chromosomes (SMC) protein complexes are key determinants of chromosome conformation. Using Hi-C and polymer modelling, we study how cohesin and condensin, two deeply conserved SMC complexes, organize chromosomes in the budding yeast Saccharomyces cerevisiae. The canonical role of cohesin is to co-align sister chromatids, while condensin generally compacts mitotic chromosomes. We find strikingly different roles for the two complexes in budding yeast mitosis. First, cohesin is responsible for compacting mitotic chromosome arms, independently of sister chromatid cohesion. Polymer simulations demonstrate that this role can be fully accounted for through cis-looping of chromatin. Second, condensin is generally dispensable for compaction along chromosome arms. Instead, it plays a targeted role compacting the rDNA proximal regions and promoting resolution of peri-centromeric regions. Our results argue that the conserved mechanism of SMC complexes is to form chromatin loops and that distinct SMC-dependent looping activities are selectively deployed to appropriately compact chromosomes

Oxaliplatin, irinotecan and capecitabine (OCX) for first-line treatment of advanced/metastatic colorectal cancer: a phase I trial (SAKK 41/03)

BACKGROUND: A phase I multicentre trial was conducted to define the recommended dose of capecitabine in combination with oxaliplatin and irinotecan (OCX) in metastatic colorectal cancer. PATIENTS AND METHODS: Patients with performance status (PS) < 2 and adequate haematological, renal and liver function received oxaliplatin 70 mg/m(2) on days 1 and 15, irinotecan 100 mg/m(2) on days 8 and 22 and one of five dose levels (DL 1-5, between 800 and 1,600 mg/ m(2)) of capecitabine on days 1-29 every 5 weeks. RESULTS: 23 patients received a median of 3 cycles. 3 dose-limiting toxicities occurred (DL 1: grade 3 (G3) elevated alkaline phosphatase; DL 5: 1 patient G4 hyperglycaemia/G3 diarrhoea and 1 sudden death). The most common severe adverse event was G3 diarrhoea (13%). Severe haematotoxicity was rare. Therapy was stopped mainly due to metastasectomy or tumour progression (7 patients each). 8 patients reached a partial response. Median time to progression and overall survival (OS) were 8.0 and 21.9 months, respectively. CONCLUSIONS: The recommended capecitabine dose in this schedule is 1,400 mg/m(2) daily. The OCX regimen is well tolerated. The response rate was surprisingly low with progression-free survival (PFS) and OS within the range of a triple combination. Further studies in combination with targeted agents are warranted

Adjuvant treatment recommendations for patients with ER-positive/HER2-negative early breast cancer by Swiss tumor boards using the 21-gene recurrence score (SAKK 26/10)

BACKGROUND: To evaluate the effect of Recurrence Score® results (RS; Oncotype DX® multigene assay ODX) on treatment recommendations by Swiss multidisciplinary tumor boards (TB). METHODS: SAKK 26/10 is a multicenter, prospective cohort study of early breast cancer patients: Eligibility: R0-resection, ≥10% ER+ malignant cells, HER2-, pN0/pN1a. Patients were stratified into low-risk (LR) and non-low-risk (NLR) groups based on involved nodes (0 vs 1-3) and five additional predefined risk factors. Recommendations were classified as hormonal therapy (HT) or chemotherapy plus HT (CT + HT). Investigators were blinded to the statistical analysis plan. A 5%/10% rate of recommendation change in LR/NLR groups, respectively, was assumed independently of RS (null hypotheses). RESULTS: Two hundred twenty two evaluable patients from 18 centers had TB recommendations before and after consideration of the RS result. A recommendation change occurred in 45 patients (23/154 (15%, 95% CI 10-22%) in the LR group and 22/68 (32%, 95% CI 22-45%) in the NLR group). In both groups the null hypothesis could be rejected (both p < 0.001). Specifically, in the LR group, only 5/113 (4%, 95% CI 1-10%) with HT had a recommendation change to CT + HT after consideration of the RS, while 18/41 (44%, 95% CI 28-60%) of patients initially recommended CT + HT were subsequently recommended only HT. In the NLR group, 3/19 (16%, 95% CI 3-40%) patients were changed from HT to CT + HT, while 19/48 (40%, 95% CI 26-55%) were changed from CT + HT to HT. CONCLUSION: There was a significant impact of using the RS in the LR and the NLR group but only 4% of LR patients initially considered for HT had a recommendation change (RC); therefore these patients could forgo ODX testing. A RC was more likely for NLR patients considered for HT. Patients considered for HT + CT have the highest likelihood of a RC based on RS

Early metabolic responses in temozolomide treated low-grade glioma patients

Amino acid transport and protein synthesis are important steps of tumor growth. We investigated the time course of tumor metabolism in low-grade gliomas (LGG) during temozolomide chemotherapy, and compared metabolic responses as measured with positron emission tomography (PET) with volume responses as revealed by magnetic resonance imaging (MR). A homogeneous population of 11 patients with progressive non-enhancing LGG was prospectively studied. Imaging was done at 6-months intervals starting six months, and in a second series starting three months after treatment initiation. F-18 fluoro-ethyl-l-tyrosine (FET) uptake was quantified with PET as metabolically active tumor volume, and was compared with the tumor volume on MR. Response was defined as ≥10% reduction of the initial tumor volume. Eight patients showed metabolic responses. Already 3 months after start of chemotherapy the active FET volumes decreased in 2 patients to a mean of 44% from baseline. First MR volume responses were noted at 6 months. Responders showed a volume reduction to 31 ± 23% (mean ± SD) from baseline for FET, and to 73 ± 26% for MR. The time to maximal volume reduction was 8.0 ± 4.4 months for FET, and 15.0 ± 3.0 months for MR. The initial metabolic response correlated with the best volume response on MR (Spearman Rank P = 0.011). Deactivation of amino acid transport represents an early indicator of chemotherapy response in LGG. Response assessment based on MR only has to be reconsidered. The time window obtained from PET may assist for individual treatment decisions in LGG patients