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Exposure to ionizing radiation increases the risk of myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN), but such risks are not known in well-differentiated thyroid cancer (WDTC) patients treated with radioactive iodine (RAI). A total of 148 215 WDTC patients were identified from Surveillance, Epidemiology and End Results registries between 1973 and 2014, of whom 54% underwent definitive thyroidectomy and 46% received adjuvant RAI. With a median follow-up of 6.6 years, 77 and 66 WDTC patients developed MDS and MPN, respectively. Excess absolute risks for MDS and MPN from RAI treatment when compared to background rates in the US population were 6.6 and 8.1 cases per 100 000 person-years, respectively. Compared to background population rates, relative risks of developing MDS (3.85 (95% confidence interval, 1.7–7.6); P=0.0005) and MPN (3.13 (1.1–6.8); P=0.012) were significantly elevated in the second and third year following adjuvant RAI therapy, but not after thyroidectomy alone. The increased risk was significantly associated with WDTC size ⩾2 cm or regional disease. Development of MDS was associated with shorter median overall survival in WDTC survivors (10.3 vs 22.5 years; P<0.001). These data suggest that RAI treatment for WDTC is associated with increased risk of MDS with short latency and poor survival.

The biology, clinical phenotype and progression rate of chronic myelomonocytic leukemia (CMML) are highly variable due to diverse initiating and secondary clonal genetic events. To determine the effects of molecular features including clonal hierarchy in CMML, we studied whole-exome and targeted next-generation sequencing data from 150 patients with robust clinical and molecular annotation assessed cross-sectionally and at serial time points of disease evolution. To identify molecular lesions unique to CMML, we compared it to the related myeloid neoplasms (N=586), including juvenile myelomonocytic leukemia, myelodysplastic syndromes (MDS) and primary monocytic acute myeloid leukemia and discerned distinct molecular profiles despite similar pathomorphological features. Within CMML, mutations in certain pathways correlated with clinical classification, for example, proliferative vs dysplastic features. While most CMML patients (59%) had ancestral (dominant/co-dominant) mutations involving TET2, SRSF2or ASXL1genes, secondary subclonal hierarchy correlated with clinical phenotypes or outcomes. For example, progression was associated with acquisition of new expanding clones carrying biallelic TET2mutations or RASfamily, or spliceosomal gene mutations. In contrast, dysplastic features correlated with mutations usually encountered in MDS (for example, SF3B1and U2AF1). Classification of CMML based on hierarchies of ancestral and subclonal mutational events may correlate strongly with clinical features and prognosis.

To minimize adverse events (AEs) unrelated to drugs and maximize the likelihood of drug approvals, eligibility criteria for randomized controlled trials (RCTs) may be overly restrictive. The purpose of this study was to determine if RCTs in hematologic malignancies exclude patients irrespective of known toxicities or observed AEs. MEDLINE was searched from 1/2010 to 1/2015 for RCTs published in high-impact journals. Of 97 trials, 33% were conducted in leukemia, 28% in lymphoma, 34% in multiple myeloma and 5% in myelodysplastic syndromes or myelofibrosis. Expected toxicities at thresholds of ⩾10%, ⩾5% and <5% were not correlated with cardiac, hepatic or renal eligibility criteria (logistic regression). To explore this lack of correlation we tested the concordance of expected toxicities and eligibility criteria using a modified version of McNemar’s test: at each threshold, hepatic, renal and cardiac expected toxicities were significantly discordant with eligibility criteria. Hepatic and renal eligibility criteria were also not correlated with observed AEs, P=0.69 and P=0.77, respectively, but a significant correlation was detected between cardiac eligibility criteria and observed AEs, P=0.02. Thus, the analyzed RCTs excluding patients with organ dysfunction do not reflect expected toxicities, based on prescription drug labels/prior experience, or reported AEs on the trials.

The Revised International Prognostic Scoring System (IPSS-R) was developed for untreated myelodysplastic syndrome (MDS) patients based on clinical data. We created and validated a new model that incorporates mutational data to improve the predictive capacity of the IPSS-R in treated MDS patients. Clinical and mutational data from treated MDS patients diagnosed between January 2000 and January 2012 were used to develop the new prognostic system. A total of 508 patients were divided into training (n=333) and validation (n=175) cohorts. Independent significant prognostic factors for survival included age, IPSS-R, EZH2, SF3B1and TP53. Weighted coefficients for each factor were used to build the new linear predictive model, which produced four prognostic groups: low, intermediate-1, intermediate-2 and high with a median overall survival of 37.4, 23.2, 19.9 and 12.2 months, respectively, P<0.001. Significant improvement in the C-index of the new model (0.73) was observed compared with the IPSS-R (0.69). The new model predicted outcome both in a separate validation cohort and in another cohort of patients with paired samples at different time points during their disease course. The addition of mutational data to the IPSS-R makes it dynamic and enhances its predictive ability in treated MDS patients regardless of their initial or subsequent therapies.

Genetic and epigenetic aberrations contribute to the initiation and progression of acute myeloid leukemia (AML). GFI1, a zinc-finger transcriptional repressor, exerts its function by recruiting histone deacetylases to target genes. We present data that low expression of GFI1is associated with an inferior prognosis of AML patients. To elucidate the mechanism behind this, we generated a humanized mouse strain with reduced GFI1expression (GFI1-KD). Here we show that AML development induced by onco-fusion proteins such as MLL-AF9 or NUP98-HOXD13 is accelerated in mice with low human GFI1expression. Leukemic cells from animals that express low levels of GFI1show increased H3K9 acetylation compared to leukemic cells from mice with normal human GFI1expression, resulting in the upregulation of genes involved in leukemogenesis. We investigated a new epigenetic therapy approach for this subgroup of AML patients. We could show that AML blasts from GFI1-KDmice and from AML patients with low GFI1levels were more sensitive to treatment with histone acetyltransferase inhibitors than cells with normal GFI1expression levels. We suggest therefore that GFI1 has a dose-dependent role in AML progression and development. GFI1 levels are involved in epigenetic regulation, which could open new therapeutic approaches for AML patients.

Risks of acute myeloid leukemia (AML) and/or myelodysplastic syndromes (MDS) are known to increase after cancer treatments. Their rise-and-fall dynamics and their associations with radiation have, however, not been fully characterized. To improve risk definition we developed SEERaBomb R software for Surveillance, Epidemiology and End Results second cancer analyses. Resulting high-resolution relative risk (RR) time courses were compared, where possible, to results of A-bomb survivor analyses. We found: (1) persons with prostate cancer receiving radiation therapy have increased RR of AML and MDS that peak in 1.5–2.5 years; (2) persons with non-Hodgkin lymphoma (NHL), lung and breast first cancers have the highest RR for AML and MDS over the next 1–12 years. These increased RR are radiation specific for lung and breast cancer but not for NHL; (3) AML latencies were brief compared to those of A-bomb survivors; and (4) there was a marked excess risk of acute promyelocytic leukemia in persons receiving radiation therapy. Knowing the type of first cancer, if it was treated with radiation, the interval from first cancer diagnosis to developing AML or MDS, and the type of AML, can improve estimates of whether AML or MDS cases developing in this setting are due to background versus other processes.

Can qualitative metabolite time course predictions be inferred from measured mRNA expression patterns? Speaking against this possibility is the large number of 'decoupling' control points that lie between these variables, i.e. translation, protein degradation, enzyme inhibition and enzyme activation. Speaking for it is the notion that these control points might be coordinately regulated such that action exerted on the mRNA level is informative of action exerted on the protein and metabolite levels. A simple kinetic model of sphingoid base metabolism in yeast is postulated. When the enzyme activities in this model are modulated proportional to mRNA expression levels measured in heat shocked yeast, the model yields a transient rise and fall in sphingoid bases followed by a permanent rise in ceramide. This finding is in qualitative agreement with experiments and is thus consistent with the aforementioned coordinated control system hypothesis. Copyright © 2001 John Wiley & Sons, Ltd.

Abstract: Radiation-induced human papillary thyroid cancer (PTC) is associated with chromosomal inversions that involve the genetic loci H4 and RET on chromosome 10. Recently, experimental data has shown that these loci lie in very close spatial proximity in a high proportion of adult human thyroid cells. Applying the generalized formulation of dual radiation action to this H4-to-RET geometric distance data, we predict here the radiation dose-response of H4-RET induction. The predicted H4-RET dose-response has a linear-to-quadratic transition dose of ∼7 Gy, suggesting the validity of linear risk extrapolations to very low doses for H4-RET mediated radiation-induced PTC. In conjunction with A-bomb survivor data, the predicted H4-RET dose- response yields estimates of the number of PTC target cells that are of the order of ∼106 to ∼107 cells, i.e. considerably less than the total number of follicular cells in the thyroid gland.

Abstract: Chronic myeloid leukemia (CML) invites biologically based radiation risk modeling because CML is simultaneously well-understood, homogeneous and prevalent. CML is known to be caused by a translocation involving the ABL and BCR genes, almost all CML patients have the BCR-ABL translocation, and CML is prevalent enough that its induction is unequivocally detected among Hiroshima A-bomb survivors. In a previous paper, a linear-quadratic-exponential (LQE) dose- response model was used to estimate the lifetime excess risk of CML in the limit of low doses of γ-rays, R γ. This estimate assumed that BCR-ABL translocation dose- response curves in stem cells for both neutrons and γ-rays, differ only by a common proportionality constant from dicentric aberration dose-response curves in lymphocytes. In the present paper we challenge this assumption by predicting the BCR-ABL dose response. The predictions are based on the biophysical theory of dual radiation action (TDRA) as it applies to recent BCR-to-ABL distance data in G0 human lymphocytes; this data shows BCR and ABL geometric distributions that are not uniform and not independent, with close association of the two genes in some cells. The analysis speaks against the previous proportionality assumption. We compute 11 plausible LQE estimates of R γ, 2 based on the proportionality assumption and 9 based on TDRA predictions. For each estimate of R γ we also compute an associated estimate of the number of CML target cells, N; the biological basis of the LQE model allows us to form such estimates. Consistency between N and hematological considerations provides a plausibility check of the risk estimates. Within the group of estimates investigated, the most plausible lifetime excess risk estimates tend to lie near R γ=0.01 Gy–1, substantially higher than risk estimates based on the proportionality assumption.

Abstract: The Sax-Markov binary eurejoining/misrejoining (SMBE) model is a stochastic representation of Sax’s breakage-and-reunion mechanism of misrejoining DNA double-strand breaks (DSBs). In this model, to approximate DSB misrejoining probabilities that decrease with increasing distance, the nucleus is treated as a collection ofη isolated nuclear subvolumes called sites; DSB free ends within the same site interact with a probability that is independent of distance, and DSB free ends within different sites never interact. In our previous work, SMBE steady-state solutions were used to estimateη from a combination of high-dose PFGE (pulsed-field gel electrophoresis) data and moderate-dose chromosomal aberration data. Here, analytic SMBE transient solutions (i.e., time courses of DSBs and misrejoinings) are derived and used to estimateη from various sets of misrejoining DSB kinetic data. The time courses are multiexponentials with rate constantsκ, 6κ, 15κ, ... j(2j–1)κ corresponding to different nuclear site states and not different types of DSBs. For example, theκ component corresponds to nuclear sites with two DSB free ends and thus only one possible rejoining interaction, and the 6κ component corresponds to sites with four DSB free ends and thus six (four choose two) potential rejoining interactions – four of these six potential interactions lead to a final state of two misrejoinings and the other two of six lead to a final state of correct repair (unrejoinable DSBs are not represented in the SMBE model). The SMBE time course solutions provide site number estimates that fall in the range ofη≈10–100 for premature chromosome condensation (PCC) data andη≈1000 for PFGE data.

Modern methods of genomics have produced an unprecedented amount of raw data. The interpretation and explanation of these data constitute a major, well-recognized challenge.

Abstract: Estimation of the number of hematopoietic stem cells capable of causing chronic myeloid leukemia (CML) is relevant to the development of biologically based risk models of radiation-induced CML. Through a comparison of the age structure of CML incidence data from the Surveillance, Epidemiology, and End Results (SEER) Program and the age structure of chromosomal translocations found in healthy subjects, the number of CML target stem cells is estimated for individuals above 20 years of age. The estimation involves three steps. First, CML incidence among adults is fit to an exponentially increasing function of age. Next, assuming a relatively short waiting time distribution between BCR-ABL induction and the appearance of CML, an exponential age function with rate constants fixed to the values found for CML is fitted to the translocation data. Finally, assuming that translocations are equally likely to occur between any two points in the genome, the parameter estimates found in the first two steps are used to estimate the number of target stem cells for CML. The population-averaged estimates of this number are found to be 1.86×108 for men and 1.21×108 for women; the 95% confidence intervals of these estimates are (1.34×108, 2.50×108) and (0.84×108, 1.83×108), respectively.