Transcriptomic and clinical heterogeneity of metastatic disease timing within metastatic castration-sensitive prostate cancer.

BACKGROUND: Metastatic castration-sensitive prostate cancer (mCSPC) is commonly classified into high- and low-volume subgroups which have demonstrated differential biology, prognosis, and response to therapy. Timing of metastasis has similarly demonstrated differences in clinical outcomes; however, less is known about any underlying biologic differences between these disease states. Herein, we aim to compare transcriptomic differences between synchronous and metachronous mCSPC and identify any differential responses to therapy. PATIENTS AND METHODS: We performed an international multi-institutional retrospective review of men with mCSPC who completed RNA expression profiling evaluation of their primary tumor. Patients were stratified according to disease timing (synchronous versus metachronous). The primary endpoint was to identify differences in transcriptomic profiles between disease timing. The median transcriptomic scores between groups were compared with the Mann-Whitney U test. Secondary analyses included determining clinical and transcriptomic variables associated with overall survival (OS) from the time of metastasis. Survival analysis was carried out with the Kaplan-Meier method and multivariable Cox regression. RESULTS: A total of 252 patients were included with a median follow-up of 39.6 months. Patients with synchronous disease experienced worse 5-year OS (39% versus 79%; P < 0.01) and demonstrated lower median androgen receptor (AR) activity (11.78 versus 12.64; P < 0.01) and hallmark androgen response (HAR; 3.15 versus 3.32; P < 0.01). Multivariable Cox regression identified only high-volume disease [hazard ratio (HR) = 4.97, 95% confidence interval (CI) 2.71-9.10; P < 0.01] and HAR score (HR = 0.51, 95% CI 0.28-0.88; P = 0.02) significantly associated with OS. Finally, patients with synchronous (HR = 0.47, 95% CI 0.30-0.72; P < 0.01) but not metachronous (HR = 1.37, 95% CI 0.50-3.92; P = 0.56) disease were found to have better OS with AR and non-AR combination therapy as compared with monotherapy (P value for interaction = 0.05). CONCLUSIONS: We have demonstrated a potential biologic difference between metastatic timing of mCSPC. Specifically, for patients with low-volume disease, those with metachronous low-volume disease have a more hormone-dependent transcriptional profile and exhibit a better prognosis than synchronous low-volume disease.

Transcriptional profiling of primary prostate tumor in metastatic hormone-sensitive prostate cancer and association with clinical outcomes: correlative analysis of the E3805 CHAARTED trial.

BACKGROUND: The phase III CHAARTED trial established upfront androgen-deprivation therapy (ADT) plus docetaxel (D) as a standard for metastatic hormone-sensitive prostate cancer (mHSPC) based on meaningful improvement in overall survival (OS). Biological prognostic markers of outcomes and predictors of chemotherapy benefit are undefined. PATIENTS AND METHODS: Whole transcriptomic profiling was performed on primary PC tissue obtained from patients enrolled in CHAARTED prior to systemic therapy. We adopted an a priori analytical plan to test defined RNA signatures and their associations with HSPC clinical phenotypes and outcomes. Multivariable analyses (MVAs) were adjusted for age, Eastern Cooperative Oncology Group status, de novo metastasis presentation, volume of disease, and treatment arm. The primary endpoint was OS; the secondary endpoint was time to castration-resistant PC. RESULTS: The analytic cohort of 160 patients demonstrated marked differences in transcriptional profile compared with localized PC, with a predominance of luminal B (50%) and basal (48%) subtypes, lower androgen receptor activity (AR-A), and high Decipher risk disease. Luminal B subtype was associated with poorer prognosis on ADT alone but benefited significantly from ADT + D [OS: hazard ratio (HR) 0.45; P = 0.007], in contrast to basal subtype which showed no OS benefit (HR 0.85; P = 0.58), even in those with high-volume disease. Higher Decipher risk and lower AR-A were significantly associated with poorer OS in MVA. In addition, higher Decipher risk showed greater improvements in OS with ADT + D (HR 0.41; P = 0.015). CONCLUSION: This study demonstrates the utility of transcriptomic subtyping to guide prognostication in mHSPC and potential selection of patients for chemohormonal therapy, and provides proof of concept for the possibility of biomarker-guided selection of established combination therapies in mHSPC.

First-principles examination of two-dimensional Janus quintuple-layer atomic structures XCrSiN2 (X = S, Se, and Te).

In this work, we propose novel two-dimensional Janus XCrSiN2 (X = S, Se, and Te) single-layers and comprehensively investigate their crystal structure, electronic properties, and carrier mobility by using a first-principles method. These configurations are the combination of the CrSi2N4 material and a transition metal dichalcogenide. The X-Cr-SiN2 single-layers are constructed by replacing the N-Si-N atomic layer on one side with chalcogen atoms (S, Se, or Te). The structural characteristics, mechanical or thermal stabilities, and electronic properties are investigated adequately. All three examined configurations are energetically stable and are all small-bandgap semiconductors (<1 eV). Since the mirror symmetry is broken in the Janus material, there exists a remarkable built-in electric field and intrinsic dipole moment. Therefore, the spin-orbit interaction is considered intensively. However, it is observed that the spin-orbit coupling has insignificant effects on the electronic properties of XCrSiN2 (X = S, Se, and Te). Moreover, an external electric field and strain are applied to evaluate the adjustment of the electronic features of the three structures. The transport properties of the proposed configurations are calculated and analyzed systematically, indicating the highly directional isotropy. Our results suggest that the proposed Janus XCrSiN2 could be potential candidates for various applications, especially in nanoscale electronic devices.

New C 2h phase of group III monochalcogenide monolayers AlX (X = S, Se, and Te) with anisotropic crystal structure: first-principles study.

In this paper, we introduce a new phase of two-dimensional aluminum monochalcogenide, namely C 2h-AlX (X = S, Se, and Te). With the C 2h space group, C 2h-AlX possesses a large unit cell containing 8 atoms. The C 2h phase of AlX monolayers is found to be dynamically and elastically stable based on the evaluation of its phonon dispersions and elastic constants. The anisotropic atomic structure of C 2h-AlX leads to a strong anisotropy in its mechanical properties with Young's modulus and Poisson's ratio strongly dependent on the directions examined in the two-dimensional plane. All three monolayers of C 2h-AlX are found to be direct band gap semiconductors, which are compared with the indirect band gap semiconductors of available D 3h-AlX. Particularly, the transition from direct to indirect band gap is observed in C 2h-AlX when a compressive biaxial strain is applied. Our calculated results indicate that C 2h-AlX exhibits anisotropic optical characteristics and its absorption coefficient is high. Our findings suggest that C 2h-AlX monolayers are suitable for applications in next-generation electro-mechanical and anisotropic opto-electronic nanodevices.

Structural, electronic, and transport properties of Janus GaInX2(X=S, Se, Te) monolayers: first-principles study.

Two-dimensional Janus monolayers have outstanding electronic and transport properties due to their asymmetric atomic structures. In the present work, we systematically study the structural, electronic, and transport properties of the Janus GaInX2(X= S, Se, Te) monolayers by using the first-principles calculations. The stability of the investigated monolayers is confirmed via the analysis of vibrational spectrum and molecular dynamics simulations. Our calculations demonstrate that while GaInS2and GaInSe2monolayers are direct semiconductors, GaInTe2monolayer exhibits the characteristics of an indirect semiconductor. The band gap of GaInX2decreases when the chalcogen elementXvaries from S to Te. Obtained results reveal that small spin-orbit splitting energy in the valence band is found around the Γ point of the Brillouin zone when the spin-orbit coupling is included. Interestingly, GaInS2and GaInSe2have high and directional isotropic electron mobility meanwhile the directional anisotropy of the electron mobility is found in the Janus GaInTe2monolayer. Our findings not only present superior physical properties of GaInX2monolayers but also show promising potential applications of these materials in nanoelectronic devices.

First-principles insights onto structural, electronic and optical properties of Janus monolayers CrXO (X = S, Se, Te).

The lacking of the vertical mirror symmetry in Janus structures compared to their conventional metal monochalcogenides/dichalcogenides leads to their characteristic properties, which are predicted to play significant roles for various promising applications. In this framework, we systematically examine the structural, mechanical, electronic, and optical properties of the two-dimensional 2H Janus CrXO (X = S, Se, Te) monolayers by using first-principles calculation method based on density functional theory. The obtained results from optimization, phonon spectra, and elastic constants demonstrate that all three Janus monolayers present good structural and mechanical stabilities. The calculated elastic constants also indicate that the Janus CrTeO monolayer is much mechanically flexible than the other two monolayers due to its low Young's modulus value. The metallic behavior is observed at the ground state for the Janus CrSeO and CrTeO monolayers in both PBE and HSE06 levels. Meanwhile, the Janus CrSO monolayer exhibits a low indirect semiconducting characteristic. The bandgap of CrSO after the correction of HSE06 hybrid functional is the average value of its binary transition metal dichalcogenides. The broad absorption spectrum of CrSO reveals the wide activated range from the visible to near-ultraviolet region. Our findings not only present insight into the brand-new Janus CrXO monolayers but can also motivate experimental research for several applications in optoelectric and nanoelectromechanical devices.

Efficient formation of bipolar microtubule bundles requires microtubule-bound gamma-tubulin complexes.

The mechanism for forming linear microtubule (MT) arrays in cells such as neurons, polarized epithelial cells, and myotubes is not well understood. A simpler bipolar linear array is the fission yeast interphase MT bundle, which in its basic form contains two MTs that are bundled at their minus ends. Here, we characterize mto2p as a novel fission yeast protein required for MT nucleation from noncentrosomal gamma-tubulin complexes (gamma-TuCs). In interphase mto2Delta cells, MT nucleation was strongly inhibited, and MT bundling occurred infrequently and only when two MTs met by chance in the cytoplasm. In wild-type 2, we observed MT nucleation from gamma-TuCs bound along the length of existing MTs. We propose a model on how these nucleation events can more efficiently drive the formation of bipolar MT bundles in interphase. Key to the model is our observation of selective antiparallel binding of MTs, which can both explain the generation and spatial separation of multiple bipolar bundles.

Multidisciplinary total eradication therapy (TET) in men with newly diagnosed oligometastatic prostate cancer.

To evaluate the outcomes of total eradication therapy (TET), designed to eradicate all sites of visible cancer and micrometastases, in men with newly diagnosed oligometastatic prostate cancer (OMPCa). Men with ≤ 5 sites of metastases were enrolled in a prospective registry study, underwent neoadjuvant chemohormonal therapy, followed by radical prostatectomy, adjuvant radiation (RT) to prostate bed/pelvis, stereotactic body radiation therapy (SBRT) to oligometastases, and adjuvant hormonal therapy (HT). When possible, the prostate-specific membrane antigen targeted 18F-DCFPyL PET/CT (18F-DCFPyL) scan was obtained, and abiraterone was added to neoadjuvant HT. Twelve men, median 55 years, ECOG 0, median PSA 14.7 ng/dL, clinical stages M0-1/12 (8%), M1a-3/12 (25%) and M1b-8/12 (67%), were treated. 18F-DCFPyL scan was utilized in 58% of cases. Therapies included prostatectomy 12/12 (100%), neoadjuvant [docetaxel 11/12 (92%), LHRH agonist 12/12 (100%), abiraterone + prednisone 6/12 (50%)], adjuvant radiation [RT 2/12 (17%), RT + SBRT 4/12 (33%), SBRT 6/12 (50%)], and LHRH agonist 12/12 (100%)]. 2/5 (40%) initial patients developed neutropenic fever (NF), while 0/6 (0%) subsequent patients given modified docetaxel dosing developed NF. Otherwise, TET resulted in no additive toxicities. Median follow-up was 48.8 months. Overall survival was 12/12 (100%). 1-, 2-, and 3-year undetectable PSA's were 12/12 (100%), 10/12 (83%) and 8/12 (67%), respectively. Median time to biochemical recurrence was not reached. The outcomes suggest TET in men with newly diagnosed OMPCa is safe, does not appear to cause additive toxicities, and may result in an extended interval of undetectable PSA.

Rsp1p, a J domain protein required for disassembly and assembly of microtubule organizing centers during the fission yeast cell cycle.

Regulation of microtubule organizing centers (MTOCs) orchestrates the reorganization of the microtubule (MT) cytoskeleton. In the fission yeast Schizosaccharomyces pombe, an equatorial MTOC (eMTOC) at the cell division site disassembles after cytokinesis, and multiple interphase MTOCs (iMTOCs) appear on the nucleus. Here, we show that, upon eMTOC disassembly, small satellites carrying MTOC components such as the gamma-tubulin complex travel in both directions along interphase MTs. We identify rsp1p, an MTOC protein required for eMTOC disassembly. In rsp1 loss-of-function mutants, the eMTOC persists and organizes an abnormal microtubule aster, while iMTOCs and satellites are greatly reduced. Conversely, rsp1p overexpression inhibits eMTOC formation. Rsp1p is a J domain protein that interacts with an hsp70. Thus, our findings suggest a model in which rsp1p is part of a chaperone-based mechanism that disassembles the eMTOC into satellites, contributing to the dynamic redistribution of MTOC components for organization of interphase microtubules.

A metastable intermediate state of microtubule dynamic instability that differs significantly between plus and minus ends.

The current two-state GTP cap model of microtubule dynamic instability proposes that a terminal crown of GTP-tubulin stabilizes the microtubule lattice and promotes elongation while loss of this GTP-tubulin cap converts the microtubule end to shortening. However, when this model was directly tested by using a UV microbeam to sever axoneme-nucleated microtubules and thereby remove the microtubule's GTP cap, severed plus ends rapidly shortened, but severed minus ends immediately resumed elongation (Walker, R.A., S. Inoué, and E.D. Salmon. 1989. J. Cell Biol. 108: 931-937). To determine if these previous results were dependent on the use of axonemes as seeds or were due to UV damage, or if they instead indicate an intermediate state in cap dynamics, we performed UV cutting of self-assembled microtubules and mechanical cutting of axoneme-nucleated microtubules. These independent methods yielded results consistent with the original work: a significant percentage of severed minus ends are stable after cutting. In additional experiments, we found that the stability of both severed plus and minus ends could be increased by increasing the free tubulin concentration, the solution GTP concentration, or by assembling microtubules with guanylyl-(alpha,beta)-methylene-diphosphonate (GMPCPP). Our results show that stability of severed ends, particularly minus ends, is not an artifact, but instead reveals the existence of a metastable kinetic intermediate state between the elongation and shortening states of dynamic instability. The kinetic properties of this intermediate state differ between plus and minus ends. We propose a three-state conformational cap model of dynamic instability, which has three structural states and four transition rate constants, and which uses the asymmetry of the tubulin heterodimer to explain many of the differences in dynamic instability at plus and minus ends.

A mechanism for nuclear positioning in fission yeast based on microtubule pushing.

The correct positioning of the nucleus is often important in defining the spatial organization of the cell, for example, in determining the cell division plane. In interphase Schizosaccharomyces pombe cells, the nucleus is positioned in the middle of the cylindrical cell in an active microtubule (MT)-dependent process. Here, we used green fluorescent protein markers to examine the dynamics of MTs, spindle pole body, and the nuclear envelope in living cells. We find that interphase MTs are organized in three to four antiparallel MT bundles arranged along the long axis of the cell, with MT plus ends facing both the cell tips and minus ends near the middle of the cell. The MT bundles are organized from medial MT-organizing centers that may function as nuclear attachment sites. When MTs grow to the cell tips, they exert transient forces produced by plus end MT polymerization that push the nucleus. After an average of 1.5 min of growth at the cell tip, MT plus ends exhibit catastrophe and shrink back to the nuclear region before growing back to the cell tip. Computer modeling suggests that a balance of these pushing MT forces can provide a mechanism to position the nucleus at the middle of the cell.

Ase1p organizes antiparallel microtubule arrays during interphase and mitosis in fission yeast.

Proper microtubule organization is essential for cellular processes such as organelle positioning during interphase and spindle formation during mitosis. The fission yeast Schizosaccharomyces pombe presents a good model for understanding microtubule organization. We identify fission yeast ase1p, a member of the conserved ASE1/PRC1/MAP65 family of microtubule bundling proteins, which functions in organizing the spindle midzone during mitosis. Using fluorescence live cell imaging, we show that ase1p localizes to sites of microtubule overlaps associated with microtubule organizing centers at both interphase and mitosis. ase1Delta mutants fail to form overlapping antiparallel microtubule bundles, leading to interphase nuclear positioning defects, and premature mitotic spindle collapse. FRAP analysis revealed that interphase ase1p at overlapping microtubule minus ends is highly dynamic. In contrast, mitotic ase1p at microtubule plus ends at the spindle midzone is more stable. We propose that ase1p functions to organize microtubules into overlapping antiparallel bundles both in interphase and mitosis and that ase1p may be differentially regulated through the cell cycle.

Targeting mitochondrial translation by inhibiting DDX3: a novel radiosensitization strategy for cancer treatment.

DDX3 is a DEAD box RNA helicase with oncogenic properties. RK-33 is developed as a small-molecule inhibitor of DDX3 and showed potent radiosensitizing activity in preclinical tumor models. This study aimed to assess DDX3 as a target in breast cancer and to elucidate how RK-33 exerts its anti-neoplastic effects. High DDX3 expression was present in 35% of breast cancer patient samples and correlated with markers of aggressiveness and shorter survival. With a quantitative proteomics approach, we identified proteins involved in the mitochondrial translation and respiratory electron transport pathways to be significantly downregulated after RK-33 or DDX3 knockdown. DDX3 localized to the mitochondria and DDX3 inhibition with RK-33 reduced mitochondrial translation. As a consequence, oxygen consumption rates and intracellular ATP concentrations decreased and reactive oxygen species (ROS) increased. RK-33 antagonized the increase in oxygen consumption and ATP production observed after exposure to ionizing radiation and reduced DNA repair. Overall, we conclude that DDX3 inhibition with RK-33 causes radiosensitization in breast cancer through inhibition of mitochondrial translation, which results in reduced oxidative phosphorylation capacity and increased ROS levels, culminating in a bioenergetic catastrophe.

Functional studies on the candidate ATPase domains of Saccharomyces cerevisiae MutLalpha.

Saccharomyces cerevisiae MutL homologues Mlh1p and Pms1p form a heterodimer, termed MutLalpha, that is required for DNA mismatch repair after mismatch binding by MutS homologues. Recent sequence and structural studies have placed the NH(2) termini of MutL homologues in a new family of ATPases. To address the functional significance of this putative ATPase activity in MutLalpha, we mutated conserved motifs for ATP hydrolysis and ATP binding in both Mlh1p and Pms1p and found that these changes disrupted DNA mismatch repair in vivo. Limited proteolysis with purified recombinant MutLalpha demonstrated that the NH(2) terminus of MutLalpha undergoes conformational changes in the presence of ATP and nonhydrolyzable ATP analogs. Furthermore, two-hybrid analysis suggested that these ATP-binding-induced conformational changes promote an interaction between the NH(2) termini of Mlh1p and Pms1p. Surprisingly, analysis of specific mutants suggested differential requirements for the ATPase motifs of Mlh1p and Pms1p during DNA mismatch repair. Taken together, these results suggest that MutLalpha undergoes ATP-dependent conformational changes that may serve to coordinate downstream events during yeast DNA mismatch repair.

Unscreened older men diagnosed with prostate cancer are at increased risk of aggressive disease.

BACKGROUND: To evaluate the relationship between PSA testing history and high-risk disease among older men diagnosed with prostate cancer. METHODS: Records from 1993 to 2014 were reviewed for men who underwent radiotherapy for prostate cancer at age 75 years or older. Patients were classified into one of four groups based on PSA-testing history: (1) no PSA testing; (2) incomplete/ineffective PSA testing; (3) PSA testing; or (4) cannot be determined. Outcomes of interest were National Comprehensive Cancer Network (NCCN) risk group (that is, low, intermediate or high risk) and biopsy grade at diagnosis. Multivariable logistic regression was used to determine the association between PSA testing history and high-risk cancer. RESULTS: PSA-testing history was available in 274 (94.5%) of 290 subjects meeting study criteria. In total, 148 men (54.0%) underwent PSA testing with follow-up biopsy, 72 (26.3%) underwent PSA testing without appropriate follow-up, and 54 men (19.7%) did not undergo PSA testing. Patients who underwent PSA testing were significantly less likely to be diagnosed with NCCN high-risk cancer (23.0% vs 51.6%, P<0.001). On multivariable analysis, men with no/incomplete PSA testing had more than three-fold increased odds of high-risk disease at diagnosis (odds ratio 3.39, 95% confidence interval 1.96-5.87, P<0.001) as compared to the tested population. CONCLUSIONS: Older men who underwent no PSA testing or incomplete testing were significantly more likely to be diagnosed with high-risk prostate cancer than those who were previously screened. It is reasonable to consider screening in healthy older men likely to benefit from early detection and treatment.

End-of-radiation PSA as a novel prognostic factor in patients undergoing definitive radiation and androgen deprivation therapy for prostate cancer.

BACKGROUND: In men undergoing definitive radiation for prostate cancer, it is unclear whether early biochemical response can provide additional prognostic value beyond pre-treatment risk stratification. METHODS: Prostate cancer patients consecutively treated with definitive radiation at our institution by a single provider from 1993 to 2006 and who had an end-of-radiation (EOR) PSA (n=688, median follow-up 11.2 years). We analyzed the association of an EOR PSA level, obtained during the last week of radiation, with survival outcomes. Multivariable-adjusted cox proportional hazards models were constructed to assess associations between a detectable EOR PSA (defined as ⩾0.1 ng ml-1) and biochemical failure-free survival (BFFS), metastasis-free survival (MFS), prostate cancer-specific survival (PCSS) and overall survival (OS). Kaplan-Meier survival curves were constructed, with stratification by EOR PSA. RESULTS: At the end of radiation, the PSA level was undetectable in 30% of patients. Men with a detectable EOR PSA experienced inferior 10-year BFFS (49.7% versus 64.4%, P<0.001), 10-year MFS (84.8% versus 92.0%, P=0.003), 10-year PCSS (94.3% versus 98.2%, P=0.007) and 10-year OS (75.8% versus 82.5%, P=0.01), as compared to men with an undetectable EOR PSA. Among National Comprehensive Care Network (NCCN) intermediate- and high-risk men who were treated with definitive radiation and androgen deprivation therapy (ADT), a detectable EOR PSA was more strongly associated with PCSS than initial NCCN risk level (EOR PSA: HR 5.89, 95% CI 2.37-14.65, P<0.001; NCCN risk level: HR 2.01, 95% CI 0.74-5.42, P=0.168). Main study limitations are retrospective study design and associated biases. CONCLUSIONS: EOR PSA was significantly associated with survival endpoints in men who received treatment with definitive radiation and ADT. Whether the EOR PSA can be used to modulate treatment intensity merits further investigation.

PET imaging of prostate-specific membrane antigen in prostate cancer: current state of the art and future challenges.

BACKGROUND: Prostate-specific membrane antigen (PSMA) is a cell surface enzyme that is highly expressed in prostate cancer (PCa) and is currently being extensively explored as a promising target for molecular imaging in a variety of clinical contexts. Novel antibody and small-molecule PSMA radiotracers labeled with a variety of radionuclides for positron emission tomography (PET) imaging applications have been developed and explored in recent studies. METHODS: A great deal of progress has been made in defining the clinical utility of this class of PET agents through predominantly small and retrospective clinical studies. The most compelling data to date has been in the setting of biochemically recurrent PCa, where PSMA-targeted radiotracers have been found to be superior to conventional imaging and other molecular imaging agents for the detection of locally recurrent and metastatic PCa. RESULTS: Early data, however, suggest that initial lymph node staging before definitive therapy in high-risk primary PCa patients may be limited, although intraoperative guidance may still hold promise. Other examples of potential promising applications for PSMA PET imaging include non-invasive characterization of primary PCa, staging and treatment planning for PSMA-targeted radiotherapeutics, and guidance of focal therapy for oligometastatic disease. CONCLUSIONS: However, all of these indications and applications for PCa PSMA PET imaging are still lacking and require large, prospective, systematic clinical trials for validation. Such validation trials are needed and hopefully will be forthcoming as the fields of molecular imaging, urology, radiation oncology and medical oncology continue to define and refine the utility of PSMA-targeted PET imaging to improve the management of PCa patients.

A phase 2 multimodality trial of docetaxel/prednisone with sunitinib followed by salvage radiation therapy in men with PSA recurrent prostate cancer after radical prostatectomy.

BACKGROUND: In men with high Gleason PC and rapid PSA progression after surgery, failure rates remain unacceptably high despite salvage radiation. We explored a novel multimodality approach of docetaxel with anti-angiogenic therapy before salvage radiotherapy (RT). METHODS: This was a phase 2 single-arm prospective open-label trial with historic controls. Eligible men had a rising PSA of 0.1-3.0 ng ml(-1) within 4 years of radical prostatectomy, no metastases except resected nodal disease, no prior androgen-deprivation therapy (ADT) and Gleason 7-10. Men received four cycles of docetaxel 70 mg m(-2) every 3 weeks with low dose prednisone and sunitinib 37.5 mg daily for 14/21 days each cycle, with no ADT. Salvage prostate bed RT (66 Gy) started at day 100. The primary end point was progression-free survival (PFS) rate at 24 months. Safety data, quality of life (QOL) and dose-limiting toxicities (DLTs) were measured over time. RESULTS: Thirty-four men accrued in this multi-institutional clinical trial: 24% of men were node positive, 47% were Gleason 8-10, median PSA at entry was 0.54. The trial was terminated prematurely owing to excess DLTs (nine) including grade 3 hand-foot syndrome (n=4), neutropenic fever (n=2), AST increase (n=1), fatigue (n=1) and vomiting with diarrhea (n=1). PFS rate at 24 months was 51% (95% CI: 33, 67%) with a median PFS of 26.2 months (95% CI: 12.5, -). Six men (17.6%) had an undetectable PSA at 2 years. CONCLUSIONS: Sunitinib and docetaxel/prednisone followed by salvage RT resulted in excess pre-specified DLTs. Although nearly half of the men experienced durable disease control, efficacy was not greater than expected with radiation alone. The use of the intermediate end point of PFS in this salvage setting permitted an early decision on further development of this combination.

Efficacy of post-operative radiation in a prostatectomy cohort adjusted for clinical and genomic risk.

BACKGROUND: To date, there have been no published trials examining the impact of salvage radiation therapy (SRT) in the post-operative setting for prostate cancer (PCa). We conducted a retrospective, comparative study of post-operative radiation following radical prostatectomy (RP) for men with pT3 disease or positive margins (adverse pathological features, APF). METHODS: 422 PCa men treated at four institutions with RP and having APF were analyzed with a primary end point of metastasis. Adjuvant radiation treatment (ART, n=111), minimal residual disease (MRD) SRT (n=70) and SRT (n=83) were defined by PSA levels of <0.2, 0.2-0.49 and ⩾0.5 ng ml(-1), respectively, before radiation therapy (RT) initiation. Remaining 157 men who did not receive additional therapy before metastasis formed the no RT arm. Clinical-genomic risk was assessed by Cancer of the Prostate Risk Assessment Post-Surgical (CAPRA-S) and Decipher. Cox regression was used to evaluate the impact of treatment on outcome. RESULTS: During the study follow-up, 37 men developed metastasis with a median follow-up of 8 years. Both CAPRA-S and Decipher had independent predictive value on multivariable analysis for metastasis (P<0.05). Adjusting for clinical-genomic risk, SRT and no RT had hazard ratios of 4.31 (95% confidence interval, 1.20-15.47) and 5.42 (95% confidence interval, 1.59-18.44) for metastasis compared with ART, respectively. No significant difference was observed between MRD-SRT and ART (P=0.28). Men with low-to-intermediate CAPRA-S and low Decipher value have a low rate of metastatic events regardless of treatment selection. In contrast, men with high CAPRA-S and Decipher benefit from ART, however the cumulative incidence of metastasis remains high. CONCLUSIONS: The decision as to the timing and need for additional local therapy following RP is nuanced and requires providers and patients to balance risks of morbidity with improved oncological outcomes. Post-RP treatment can be safely avoided for men who are low risk by clinical-genomic risk, whereas those at high risk should favor enrollment in clinical trials.

Analysis of yeast MSH2-MSH6 suggests that the initiation of mismatch repair can be separated into discrete steps.

The yeast MSH2-MSH6 complex is required to repair both base-pair and single base insertion/deletion mismatches. MSH2-MSH6 binds to mismatch substrates and displays an ATPase activity that is modulated by mispairs that are repaired in vivo. To understand early steps in mismatch repair, we analyzed mismatch repair (MMR) defective MSH2-msh6-F337A and MSH2-msh6-340 complexes that contained amino acid substitutions in the MSH6 mismatch recognition domain. While both heterodimers were defective in forming stable complexes with mismatch substrates, only MSH2-msh6-340 bound to homoduplex DNA with an affinity that was similar to that observed for MSH2-MSH6. Additional analyses suggested that stable binding to a mispair is not sufficient to initiate recruitment of downstream repair factors. Previously, we observed that MSH2-MSH6 forms a stable complex with a palindromic insertion mismatch that escapes correction by MMR in vivo. Here we show that this binding is not accompanied by either a modulation in MSH2-MSH6 ATPase activity or an ATP-dependent recruitment of the MLH1-PMS1 complex. Together, these observations suggest that early stages in MMR can be divided into distinct recognition, stable binding, and downstream factor recruitment steps.