Biological implications of whole-brain radiotherapy versus stereotactic radiosurgery of multiple brain metastases

OBJECT

The efficacy and safety of treatment with whole-brain radiotherapy (WBRT) or with stereotactic radiosurgery (SRS) for multiple brain metastases (> 10) are topics of ongoing debate. This study presents detailed dosimetric and biological information to investigate the possible clinical outcomes of these 2 modalities.

METHODS

Five patients with multiple brain metastases (n = 11-23) underwent SRS. Whole-brain radiotherapy plans were retrospectively designed with the same MR image set and the same structure set for each patient, using the standard opposing lateral beams and fractionation (3 Gy × 10). Physical radiation doses and biologically effective doses (BEDs) in WBRT and SRS were calculated for each lesion target and for the normal brain tissues for comparison of the 2 modalities in the context of clinical efficacy and published toxicities.

RESULTS

The BEDs targeted to the tumor were higher in SRS than in WBRT by factors ranging from 2.4- to 3.0- fold for the mean dose and from 3.2- to 5.3-fold for the maximum dose. In the 5 patients, mean BEDs in SRS (calculated as percentages of BEDs in WBRT) were 1.3%-34.3% for normal brain tissue, 0.7%-31.6% for the brainstem, 0.5%-5.7% for the chiasm, 0.2%-5.7% for optic nerves, and 0.6%-18.1% for the hippocampus.

CONCLUSIONS

The dose-volume metrics presented in this study were essential to understanding the safety and efficacy of WBRT and SRS for multiple brain metastases. Whole-brain radiotherapy results in a higher incidence of radiation-related toxicities than SRS. Even in patients with > 10 brain metastases, the normal CNS tissues receive significantly lower doses in SRS. The mean normal brain dose in SRS correlated with the total volume of the lesions rather than with the number of lesions treated.

Potent and selective small-molecule MCL-1 inhibitors demonstrate on-target cancer cell killing activity as single agents and in combination with ABT-263 (navitoclax)

The anti-apoptotic protein MCL-1 is a key regulator of cancer cell survival and a known resistance factor for small-molecule BCL-2 family inhibitors such as ABT-263 (navitoclax), making it an attractive therapeutic target. However, directly inhibiting this target requires the disruption of high-affinity protein-protein interactions, and therefore designing small molecules potent enough to inhibit MCL-1 in cells has proven extremely challenging. Here, we describe a series of indole-2-carboxylic acids, exemplified by the compound A-1210477, that bind to MCL-1 selectively and with sufficient affinity to disrupt MCL-1-BIM complexes in living cells. A-1210477 induces the hallmarks of intrinsic apoptosis and demonstrates single agent killing of multiple myeloma and non-small cell lung cancer cell lines demonstrated to be MCL-1 dependent by BH3 profiling or siRNA rescue experiments. As predicted, A-1210477 synergizes with the BCL-2/BCL-XL inhibitor navitoclax to kill a variety of cancer cell lines. This work represents the first description of small-molecule MCL-1 inhibitors with sufficient potency to induce clear on-target cellular activity. It also demonstrates the utility of these molecules as chemical tools for dissecting the basic biology of MCL-1 and the promise of small-molecule MCL-1 inhibitors as potential therapeutics for the treatment of cancer.

Overview of dosimetric and biological perspectives on radiosurgery of multiple brain metastases in comparison with whole brain radiotherapy

PURPOSE

Treatment option of stereotactic radiosurgery versus whole brain radiotherapy for multiple brain metastases (>10) is an ongoing debate. Detailed dosimetric and biological information are presented in this study to investigate the possible clinical outcomes.Materials and Methods: Nine patients with multiple brain metastases (11-25) underwent stereotactic radiosurgery. Whole brain radiotherapy plans are retrospectively designed with the same MR image set and the same structure set for each patient using the standard opposing lateral beams and fractionation (3 Gy × 10).Physical doses and biologically effective doses are calculated for each lesion target and the CNS normal tissues and they are compared between whole brain radiotherapy and stereotactic radiosurgery in the context of clinical efficacy and published toxicities.

RESULTS

Tumor biologically effective dose is higher in radiosurgery than in whole brain radiotherapy by factors of 3.2-5.3 in maximum dose and of 2.4-3.1 in mean dose. Biologically effective mean dose in radiosurgery is 1.3-34.3% for normal brain, 0.7-31.6% for brainstem, 0.5-5.7% for chiasm, 0.2-5.7% for optic nerves and 0.6-18.1% for hippocampus of that in whole brain radiotherapy over nine cases presented here. We also presented the dose-volume relationship for normal brain to address the dosimetric concerns in radiosurgery.

CONCLUSIONS

Dose-volume metrics presented in this study are essential to understanding the safety and efficacy of whole brain radiotherapy and/or radiosurgery for multiple brain metastases. Whole brain radiotherapy has resulted in higher incidence of radiation-related toxicities than radiosurgery. Even for patients with more than 10 brain metastases, the CNS normal tissues receive significantly lower doses in radiosurgery. Mean normal brain dose in SRS is found to correlate with the total volume of lesions rather than the number of lesions treated.

Paradoxical immune reconstitution inflammatory syndrome associated with cryptococcal meningitis in China: a 5-year retrospective cohort study

We performed a retrospective cohort study of hospitalised cryptococcal meningitis (CM) patients at a single centre to evaluate the clinical epidemiological features of paradoxical cryptococcal-related immune reconstitution inflammatory syndrome (CM-IRIS) in a setting in China. A total of 154 AIDS patients with CM were involved, and 17.5% experienced IRIS at a median of 27 days after initiation of antiretroviral therapy (ART). Overall, 3 deaths were directly attributed to IRIS. The occurrences of CM-IRIS were independently associated with the pre-ART CD4+count, pre-C-reactive protein level, and the timing of ART initiation.

Correlation research of carotid arterial sclerosis and left ventricular diastolic function in hyperthyroidism

AIM

This study aims to investigate the correlation of carotid arterial sclerosis and left ventricular diastolic function in hyperthyroidism.

METHODS

A total of 70 patients with newly-diagnosed hyperthyroidism, including 32 patients clinically cured or improved after I131 therapy, were compared with 74 healthy cases in the control group. Bilateral carotid ultrasound and echocardiography were performed in all subjects. The carotid sclerosis index B, compliance coefficient CC, pulse wave velocity (PWV) and left ventricular diastolic function parameters (mitral valve diastolic peak velocity ratio E/A, mitral annulus tissue Doppler diastolic peak velocity ratio e/a and E/e) were obtained.

RESULTS

The B, CC, PWV and E/e exhibited correlation. Pre-treatment CC was negatively correlated with E/e (r=-0.325, P<0.01), whereas B and PWV were positively correlated with E/e (r=0.270 and 0.297, P < 0.05). Post-treatment CC was negatively correlated with E/e (r=-0.462, P<0.01), whereas B and PWV were positively correlated with E/e (r=0.513 and 0.479, P<0.01).

CONCLUSION

Carotid artery function and left ventricular diastolic function of hyperthyroid patients were damaged before the treatment and recovered after the treatment. Thus, a correlation existed between them. The early detection of carotid artery function could help the early detection of cardiovascular disease in the hyperthyroid patients.

Benzo(a)pyrene-7,8-diol-9,10-epoxide induced p53-independent necrosis via the mitochondria-associated pathway involving Bax and Bak activation

Benzo(a)pyrene-7,8-diol-9,10-epoxide (BPDE) is a highly reactive DNA damage agent and can induce cell death through both p53-independent and -dependent pathways. However, little is known about the molecular mechanisms of p53-independent pathways in BPDE-induced cell death. To understand the p53-independent mechanisms, we have now examined BPDE-induced cytotoxicity in p53-deficient baby mouse kidney (BMK) cells. The results showed that BPDE could induce Bax and Bak activation, cytochrome c release, caspases activation, and necrotic cell death in the BMK cells. Bax and Bak, two key molecules of mitochondrial permeability transition pore, were interdependently activated by BPDE, with Bax and Bak translocation to and Bax/Bak homo-oligomerization in mitochondria, release of cytochrome c was induced. Importantly, cytochrome c release and necrotic cell death were diminished in BMK cells (Bax−/−), BMK cells (Bak−/−), and BMK cells (Bax−/−/Bak−/−). Furthermore, overexpression of Bcl-2 could ameliorate BPDE-induced cytochrome c release and necrosis. Together the findings suggested that BPDE-induced necrosis was modulated by the p53-independent pathway, which was related to the translocation of Bax and Bak to mitochondria, release of cytochrome c, and activation of caspases.

Family functioning in Asian families raising children with autism spectrum disorders: the role of capabilities and positive meanings

BACKGROUND

There has been increasing interest in exploring the factors contributing to successful adaptation and family functioning in ethnically and culturally diverse families who raise children with autism spectrum disorders (ASD), in order to inform more appropriate strength-based family support services. This pilot study used the Family Adjustment and Adaptation Response (FAAR) model as a theoretical framework to investigate the role of families' capabilities (coping strategies and resources of support) and positive meanings in raising a child with ASD in family functioning in an Asian context.

METHODS

Sixty-five Singaporean parents of 3- to 11-year-old children with ASD completed a series of questionnaires on demands, coping strategies, social support, positive meanings and family functioning.

RESULTS

Families reported a number of helpful coping strategies. Coping through family integration/optimism was most helpful, followed by understanding the condition and by developing esteem and psychological stability. Reported capabilities, but not positive meanings, mediated the relationship between demands and family functioning.

CONCLUSION

The findings are discussed in relation to existing literature, possible specific cultural issues, and the strengths and limitations of the study. Implications for supporting families of children with ASD in different social and cultural contexts are also discussed.

Epigenetic synergies between biotin and folate in the regulation of pro-inflammatory cytokines and repeats

The protein biotin ligase, holocarboxylase synthetase (HLCS), is a chromatin protein that interacts physically with the DNA methyltransferase DNMT1, the methylated cytosine-binding protein MeCP2 and the histone H3 K9-methyltransferase EHMT1, all of which participate in folate-dependent gene repression. Here we tested the hypothesis that biotin and folate synergize in the repression of pro-inflammatory cytokines and long-terminal repeats (LTRs), mediated by interactions between HLCS and other chromatin proteins. Biotin and folate supplementation could compensate for each other's deficiency in the repression of LTRs in Jurkat and U937 cells. For example, when biotin-deficient Jurkat cells were supplemented with folate, the expression of LTRs decreased by >70%. Epigenetic synergies were more complex in the regulation of cytokines compared with LTRs. For example, the abundance of TNF-α was 100% greater in folate- and biotin-supplemented U937 cells compared with biotin-deficient and folate-supplemented cells. The NF-κB inhibitor curcumin abrogated the effects of folate and biotin in cytokine regulation, suggesting that transcription factor signalling adds an extra layer of complexity to the regulation of cytokine genes by epigenetic phenomena. We conclude that biotin and folate synergize in the repression of LTRs and that these interactions are probably mediated by HLCS-dependent epigenetic mechanisms. In contrast, synergies between biotin and folate in the regulation of cytokines need to be interpreted in the context of transcription factor signalling.