Early Exploratory Analysis for Patient-reported Quality of Life and Dosimetric Correlates in Hypofractionated Stereotactic Body Radiation Therapy (SBRT) for Low-risk and Intermediate-risk Prostate Cancer: Interim Results from a Prospective Phase II Clinical Trial.

OBJECTIVES: Given the relative novelty of stereotactic body radiation therapy as a treatment modality low-risk and intermediate-risk prostate cancer, little data exist evaluating dosimetry and its impact on patient-reported quality of life (PR-QOL) metrics. Herein, we present an interim analysis of a phase II clinical trial of PR-QOL and dosimetric correlates. METHODS: Patients with biopsy-proven low-risk or intermediate-risk prostate cancer, prostate volume ≤100 cm, and life expectancy ≥10 years were enrolled. Expanded Prostate Cancer Index Composite (EPIC) scores were tabulated by domain and evaluated in relation to dosimetry. Paired t test was performed to compare differences in scores from baseline. Minimally important differences were established using the anchor-based approach and correlations made using the χ test. RESULTS: A total of 95 patients were analyzed with a median follow-up of 18.1 months (range, 3.0 to 76.9 mo). There were no cases of acute or late grade 3+ GI or GU toxicities. Expanded Prostate Cancer Index Composite scores in urinary obstructive/irritative domain at 1 month (-4.8, P=0.03) and bowel domain at 1, 6, and 12 months (-10.8, -6.1, and -5.2) were significantly different from pretreatment, with both returning to nonsignificant differences around 24 months. Higher bladder V37Gy (≥3.35%) was associated with both late urinary incontinence and obstructive/irritative declines. Both higher rectal D5% and rectal V36Gy >0.6 cm were correlated with an enhanced proportion of patients with late minimally important difference declines. CONCLUSIONS: Higher dose volumes for the bladder and rectum predicted for poorer PR-QOL. In contrast to prostate brachytherapy data, neither prostate volume nor urethral dosimetry at this dose schedule correlated with urinary symptoms.

Initial Results of a Prospective Study of Adjuvant Pancreatic Stereotactic Body Radiation Therapy for Close or Positive Margins.

PURPOSE: Patients with close or positive margins after surgery for pancreatic carcinoma are at a high risk for recurrence. Stereotactic body radiation therapy (SBRT) allows for safe dose escalation with great conformity and short duration of treatment. Herein, we report the initial results of a prospective observational study that evaluated the efficacy and safety of this treatment option. METHODS AND MATERIALS: Patients eligible for the study had pathologically proven T1-4N0-1M0 pancreatic adenocarcinoma with a positive margin (≤1 mm) or a close margin defined as <2.5 mm. Patients were treated with either neoadjuvant or adjuvant chemotherapy, if eligible for systemic therapy. All patients received 36 Gy in 3 fractions to the close or positive margin site. RESULTS: From February 2013 to January 2018, 50 patients were enrolled with 49 patients treated on protocol and included in the analysis. The median age was 71 years. The median clinical target volume was 11.3 cc and median planning target volume 22.0 cc. The median overall survival was 23.7 months (95% confidence interval, 13.6-33.8). Local progression-free survival at 1 and 2 years was 85% and 77%, respectively. Regional progression-free survival at 1 and 2 years was 73% and 73%, respectively. Distant metastases-free survival was 57% and 49% at 1 and 2 years, respectively. Grade 3+ radiation toxicity was only 4.1% and occurred in 2 patients. CONCLUSIONS: Adjuvant pancreatic SBRT was shown to be a safe and feasible treatment option for patients with high-risk pancreatic adenocarcinoma and close or positive margins. This is the first prospective study of SBRT in high-risk postoperative pancreatic cancer. Our results yielded significant local and regional control with low rates of acute toxicity. This technique does not interrupt the administration of systemically dosed multiagent chemotherapy and can be safely interdigitated between cycles because SBRT is only 1 week of treatment.

Is Multifocal Regression a Risk Factor for Ipsilateral Breast Tumor Recurrence in the Modern Era After Neoadjuvant Chemotherapy and Breast Conservation Therapy?

PURPOSE: Multifocal pattern of regression after neoadjuvant chemotherapy has been identified as a risk factor for ipsilateral breast tumor recurrence (IBTR). We aimed to determine the significance of multifocal regression as a predictor of IBTR after neoadjuvant chemotherapy and breast conservation therapy in the modern era. METHODS AND MATERIALS: We retrospectively reviewed 346 patients treated between November 2009 and June 2017. Pattern of regression was categorized as pathologic complete response (pCR), unifocal (tumor present as a cohesive mass), limited multifocal (single cells or clusters of cells concentrated in 1 portion of the fibrotic area), or diffuse multifocal (cells spread over entire fibrotic area). IBTR was defined as new ipsilateral invasive or noninvasive breast tumor after breast conservation therapy. Predictive factors were analyzed using Cox regression. RESULTS: Incidence of multifocal regression was 25.7% for the overall cohort and 12.2% for estrogen receptor (ER) negative/progesterone receptor (PR) negative/human epidermal growth factor receptor 2 (HER2) positive, 17.5% for triple-negative, 36.9% for ER+ or PR+/HER2-, and 38.5% for triple-positive (P < .001). With a median follow-up of 41.1 months, 4-year IBTR-free survival after pCR or unifocal regression versus multifocal regression was 94.1% versus 90.9% (P = .411). Pattern of regression (P = .010; compared to pCR, hazard ratio [HR] of 11.2 for diffuse multifocal regression, 1.65 for limited multifocal regression, and 3.81 for unifocal regression), phenotype (P = .001; compared to ER+ or PR+/HER2-, HR of 30.67 for ER-/PR-/HER2+, 25.30 for triple-negative, and 1.60 for triple-positive), and lack of nodal pCR (P = .004; HR of 3.78) predicted for IBTR on multivariate Cox regression. On multivariate subset analysis, pattern of regression and lymphovascular space invasion predicted for IBTR in hormone receptor-negative patients, but pattern of regression was not associated with IBTR for hormone receptor-positive patients. CONCLUSIONS: Multifocal regression, hormone receptor-negative phenotype, and lack of nodal pCR predict for increased risk of IBTR after neoadjuvant chemotherapy. Although more common in hormone receptor-positive disease, multifocal regression was associated with worse outcome only in hormone receptor-negative patients.

Prognostic Factors for Elderly Patients Treated With Stereotactic Body Radiation Therapy for Pancreatic Adenocarcinoma.

Introduction: Pancreatic ductal adenocarcinoma (PDAC) commonly presents later in life with a median age at diagnosis of 70 years. Unfortunately, elderly patients are significantly underrepresented in clinical trials. Stereotactic body radiation therapy (SBRT) is a promising treatment modality in this population as it has demonstrated excellent local control with minimal toxicity. We aimed to determine prognostic factors associated with outcomes in elderly patients treated with SBRT. Materials and Methods: Elderly patients older than 70 treated with SBRT for PDAC at our institution, from 2004 to 2014 were included. Our primary endpoints included overall survival (OS) and local-progression-free survival (LPFS). Secondary endpoints included regional-progression-free survival (RPFS), distant-progression-free-survival (DPFS) and radiation toxicity. Endpoints were analyzed with the Kaplan-Meier method. The association of these survival endpoints with risk factors was studied with Cox proportional hazards models. Results: We identified 145 patients with 146 lesions of pancreatic adenocarcinoma with a median age at diagnosis of 79 (range, 70.1-90.3). SBRT was delivered to a median dose of 36 Gy (IQR 24-36). Surgical resection was performed on 33.8% of the total patients. Median follow-up was 12.3 months (IQR 6.0-23.3 months) and the median survival for the entire cohort 14.0 months with a 2-year OS of 27%. Multivariate analysis (MVA) demonstrated surgery [p ≤ 0.0001, HR 0.29 (95% CI, 0.16-0.51)] and post-SBRT CA19-9 [p = 0.009, HR 1.0004 (95% CI, 1.0002-1.0005)] significantly associated with overall survival. Recurrent lesions [p = 0.0069, HR 5.1 (95% CI, 1.56-16.64)] and post-SBRT CA19-9 levels [p = 0.0107, HR 1.0005 (95% CI, 1.0001-1.0008)] were significantly associated with local control on MVA. For the entire cohort, 4.1% experienced acute grade 2+ toxicity, and 2% experienced late grade 2+ toxicity at 2 years. Conclusion: This review demonstrates prognostic factors in elderly patients with PDAC treated with SBRT. We identified surgical resection and post-SBRT CA 19-9 as predictive of overall survival in this population. Additionally, we show low acute and late toxicity following SBRT in elderly patients.

Mitochondrial dysfunction RAD51, and Ku80 proteolysis promote apoptotic effects of Dinaciclib in Bcl-xL silenced cells.

In the present study, we investigated the effect of CDK inhibitors (ribociclib, palbociclib, seliciclib, AZD5438, and dinaciclib) on malignant human glioma cells for cell viability, apoptosis, oxidative stress, and mitochondrial function using various assays. None of the CDK inhibitors induced cell death at a clinically relevant concentration. However, low nanomolar concentrations of dinaciclib showed higher cytotoxic activity against Bcl-xL silenced cells in a time- and concentration-dependent manner. This effect was not seen with other CDK inhibitors. The apoptosis-inducing capability of dinaciclib in Bcl-xL silenced cells was evidenced by cell shrinkage, mitochondrial dysfunction, DNA damage, and increased phosphatidylserine externalization. Dinaciclib was found to disrupt mitochondrial membrane potential, resulting in the release of cytochrome c, AIF, and smac/DIABLO into the cytoplasm. This was accompanied by the downregulation of cyclin-D1, D3, and total Rb. Dinaciclib caused cell cycle arrest in a time- and concentration-dependent manner and with accumulation of cells in the sub-G1 phase. Our results also revealed that dinaciclib, but not ribociclib or palbociclib or seliciclib or AZD5438 induced intrinsic apoptosis via upregulation of the levels of pro-apoptotic proteins (Bax and Bak), resulting in the activation of caspases and cleavage of PARP. We also found an additional mechanism for the dinaciclib-induced augmentation of apoptosis due to abrogation RAD51-cyclin D1 interaction, specifically proteolysis of the DNA repair proteins RAD51 and Ku80. Our results suggest that successfully interfering with Bcl-xL function may restore sensitivity to dinaciclib and could hold the promise for an effective combination therapeutic strategy.

Salvage stereotactic radiosurgery for recurrent gliomas with prior radiation therapy.

This study aims to assess the viability of salvage stereotactic radiosurgery (SRS) for recurrent malignant gliomas through assessing overall survival, local control and toxicity. We performed a retrospective review of 65 patients with 76 lesions (55 high-grade, 21 low-grade) treated with salvage SRS between 2002 and   2012. Median follow-up from salvage SRS was 14.9 months (IQR: 0.9-28.1), 8.3 months (IQR: 4.0-13.3) and 8.5 months (IQR: 3.9-15.8) for low-grade, high-grade, and combined, respectively. A 12-month overall survival from salvage SRS was 68.4, 38.7 and 47.3% for low-grade, high-grade and combined respectively. A total of 6-month local control was 86.2, 53.8 and 65.3% for low-grade, high-grade and combined, respectively. Our results indicate salvage SRS can provide acceptable survival and local control with minimal toxicity.

Survivin inhibitor YM155 induces mitochondrial dysfunction, autophagy, DNA damage and apoptosis in Bcl-xL silenced glioma cell lines.

Because the anti-apoptotic protein Bcl-xL is overexpressed in glioma, one might expect that inhibiting or silencing this gene would promote tumor cell killing. However, our studies have shown that this approach has limited independent activity, but may tip the balance in favor of apoptosis induction in response to other therapeutic interventions. To address this issue, we performed a pharmacological screen using a panel of signaling inhibitors and chemotherapeutic agents in Bcl-xL silenced cells. Although limited apoptosis induction was observed with a series of inhibitors for receptor tyrosine kinases, PKC inhibitors, Src family members, JAK/STAT, histone deacetylase, the PI3K/Akt/mTOR pathway, MAP kinase, CDK, heat shock proteins, proteasomal processing, and various conventional chemotherapeutic agents, we observed a dramatic potentiation of apoptosis in Bcl-xL silenced cells with the survivin inhibitor, YM155. Treatment with YM155 increased the release of cytochrome c, smac/DIABLO and apoptosis inducing-factor, and promoted loss of mitochondrial membrane potential, activation of Bax, recruitment of LC3-II to the autophagosomes and apoptosis in Bcl-xL silenced cells. We also found an additional mechanism for the augmentation of apoptosis due to abrogation of DNA double-strand break repair mediated by Rad51 repression and enhanced accumulation of γH2AX. In summary, our observations may provide a new insight into the link between Bcl-xL and survivin inhibition for the development of novel therapies for glioma. © 2016 Wiley Periodicals, Inc.

Dinaciclib, a Cyclin-Dependent Kinase Inhibitor Promotes Proteasomal Degradation of Mcl-1 and Enhances ABT-737-Mediated Cell Death in Malignant Human Glioma Cell Lines.

The prognosis for malignant glioma, the most common brain tumor, is still poor, underscoring the need to develop novel treatment strategies. Because glioma cells commonly exhibit genomic alterations involving genes that regulate cell-cycle control, there is a strong rationale for examining the potential efficacy of strategies to counteract this process. In this study, we examined the antiproliferative effects of the cyclin-dependent kinase inhibitor dinaciclib in malignant human glioma cell lines, with intact, deleted, or mutated p53 or phosphatase and tensin homolog on chromosome 10; intact or deleted or p14ARF or wild-type or amplified epidermal growth factor receptor. Dinaciclib inhibited cell proliferation and induced cell-cycle arrest at the G2/M checkpoint, independent of p53 mutational status. In a standard 72-hour 3-[4,5-dimethylthiazol- 2yl]-5-[3-carboxymethoxyphenyl]-2-[4-sulfophenyl]-2H, tetrazolium (MTS) assay, at clinically relevant concentrations, dose-dependent antiproliferative effects were observed, but cell death was not induced. Moreover, the combination of conventional chemotherapeutic agents and various growth-signaling inhibitors with dinaciclib did not yield synergistic cytotoxicity. In contrast, combination of the Bcl-2/Bcl-xL inhibitors ABT-263 (4-[4-[[2-(4-chlorophenyl)-5,5-dimethylcyclohexen-1-yl]methyl]piperazin-1-yl]-N-[4-[[(2R)-4-morpholin-4-yl-1-phenylsulfanylbutan-2-yl]amino]-3-(trifluoromethylsulfonyl)phenyl]sulfonylbenzamide) or ABT-737 (4-[4-[[2-(4-chlorophenyl)phenyl]methyl]piperazin-1-yl]-N-[4-[[(2R)-4-(dimethylamino)-1-phenylsulfanylbutan-2-yl]amino]-3-nitrophenyl]sulfonylbenzamide) with dinaciclib potentiated the apoptotic response induced by each single drug. The synergistic killing by ABT-737 with dinaciclib led to cell death accompanied by the hallmarks of apoptosis, including an early loss of the mitochondrial transmembrane potential; the release of cytochrome c, smac/DIABLO, and apoptosis-inducing factor; phosphatidylserine exposure on the plasma membrane surface and activation of caspases and poly ADP-ribose polymerase. Mechanistic studies revealed that dinaciclib promoted proteasomal degradation of Mcl-1. These observations may have important clinical implications for the design of experimental treatment protocols for malignant human glioma.

Enzymatic C(sp3)-H Amination: P450-Catalyzed Conversion of Carbonazidates into Oxazolidinones.

Cytochrome P450 enzymes can effectively promote the activation and cyclization of carbonazidate substrates to yield oxazolidinones via an intramolecular nitrene C-H insertion reaction. Investigation of the substrate scope shows that while benzylic/allylic C-H bonds are most readily aminated by these biocatalysts, stronger, secondary C-H bonds are also accessible to functionalization. Leveraging this "non-native" reactivity and assisted by fingerprint-based predictions, improved active-site variants of the bacterial P450 CYP102A1 could be identified to mediate the aminofunctionalization of two terpene natural products with high regio- and stereoselectivity. Mechanistic studies and KIE experiments show that the C-H activation step in these reactions is rate-limiting and proceeds in a stepwise manner, namely, via hydrogen atom abstraction followed by radical recombination. This study expands the reactivity scope of P450-based catalysts in the context of nitrene transfer transformations and provides first-time insights into the mechanism of P450-catalyzed C-H amination reactions.