Delineating the Role of βIV-Tubulins in Pancreatic Cancer: βIVb-Tubulin Inhibition Sensitizes Pancreatic Cancer Cells to Vinca Alkaloids

Pancreatic cancer (PC) is a lethal disease which is characterized by chemoresistance. Components of the cell cytoskeleton are therapeutic targets in cancer. βIV-tubulin is one such component that has two isotypes-βIVa and βIVb. βIVa and βIVb isotypes only differ in two amino acids at their C-terminus. Studies have implicated βIVa-tubulin or βIVb-tubulin expression with chemoresistance in prostate, breast, ovarian and lung cancer. However, no studies have examined the role of βIV-tubulin in PC or attempted to identify isotype specific roles in regulating cancer cell growth and chemosensitivity. We aimed to determine the role of βIVa- or βIVb-tubulin on PC growth and chemosensitivity. PC cells (MiaPaCa-2, HPAF-II, AsPC1) were treated with siRNA (control, βIVa-tubulin or βIVb-tubulin). The ability of PC cells to form colonies in the presence or absence of chemotherapy was measured by clonogenic assays. Inhibition of βIVa-tubulin in PC cells had no effect chemosensitivity. In contrast, inhibition of βIVb-tubulin in PC cells sensitized to vinca alkaloids (Vincristine, Vinorelbine and Vinblastine), which was accompanied by increased apoptosis and enhanced cell cycle arrest. We show for the first time that βIVb-tubulin, but not βIVa-tubulin, plays a role in regulating vinca alkaloid chemosensitivity in PC cells. The results from this study suggest βIVb-tubulin may be a novel therapeutic target and predictor of vinca alkaloid sensitivity for PC and warrants further investigation.

Significance of baseline and change in quality of life scores in predicting clinical outcomes in an international phase III trial of advanced pancreatic cancer: NCIC CTG PA.3

BACKGROUND

There is insufficient information regarding the prognostic significance of baseline and change in quality of life (QoL) scores on overall survival (OS) in advanced pancreatic cancer.

METHODS

QoL was assessed prospectively using the EORTC QLQ-C30 as part of the PA.3 trial of gemcitabine + erlotinib (G + E) vs. gemcitabine + placebo (G + P). Relevant variables and QoL scores at baseline and change at 8 weeks were analyzed by Cox stepwise regression to determine predictors of OS.

RESULTS

222 of 285 patients (pts) treated with G + E and 220 of 284 pts treated with G + P completed baseline QoL assessments. In a multivariable Cox analysis combining all pts, better QoL physical functioning (PF) score independently predicted longer OS (HR 0.86; CI: 0.80-0.93), as did non-white race (HR 0.64; CI: 0.44-0.95), PS 0-1 (HR 0.65; CI: 0.50-0.85), locally advanced disease (HR 0.55; CI: 0.43-0.71) and G + E (HR 0.78; CI: 0.64-0.96). Improvement in physical function at week 8 also predicted for improved survival (HR 0.89; CI: 0.81-0.97 for 10 point increase in score, p = 0.02).

CONCLUSION

In addition to clinical variables, patient reported QoL scores at baseline and change from baseline to week 8 added incremental predictive information regarding survival for advanced pancreatic cancer patients.

Characteristics of Four Upward-Pointing Cosmic-Ray-like Events Observed with ANITA

We report on four radio-detected cosmic-ray (CR) or CR-like events observed with the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload. Two of the four were previously identified as stratospheric CR air showers during the ANITA-I flight. A third stratospheric CR was detected during the ANITA-II flight. Here, we report on characteristics of these three unusual CR events, which develop nearly horizontally, 20-30 km above the surface of Earth. In addition, we report on a fourth steeply upward-pointing ANITA-I CR-like radio event which has characteristics consistent with a primary that emerged from the surface of the ice. This suggests a possible τ-lepton decay as the origin of this event, but such an interpretation would require significant suppression of the standard model τ-neutrino cross section.

Determinants of survival and attempted resection in patients with non-metastatic pancreatic cancer: An Australian population-based study

BACKGROUND

There are indications that pancreatic cancer survival may differ according to sociodemographic factors, such as residential location. This may be due to differential access to curative resection. Understanding factors associated with the decision to offer a resection might enable strategies to increase the proportion of patients undergoing potentially curative surgery.

METHODS

Data were extracted from medical records and cancer registries for patients diagnosed with pancreatic cancer between July 2009 and June 2011, living in one of two Australian states. Among patients clinically staged with non-metastatic disease we examined factors associated with survival using Cox proportional hazards models. To investigate survival differences we examined determinants of: 1) attempted surgical resection overall; 2) whether patients with locally advanced disease were classified as having resectable disease; and 3) attempted resection among those considered resectable.

RESULTS

Data were collected for 786 eligible patients. Disease was considered locally advanced for 561 (71%) patients, 510 (65%) were classified as having potentially resectable disease and 365 (72%) of these had an attempted resection. Along with age, comorbidities and tumour stage, increasing remoteness of residence was associated with poorer survival. Remoteness of residence and review by a hepatobiliary surgeon were factors influencing the decision to offer surgery.

CONCLUSIONS

This study indicated disparity in survival dependent on patients' residential location and access to a specialist hepatobiliary surgeon. Accurate clinical staging is a critical element in assessing surgical resectability and it is therefore crucial that all patients have access to specialised clinical services.

TACTIC: a multicentre, open-label, single-arm phase II trial of panitumumab, cisplatin, and gemcitabine in biliary tract cancer

PURPOSE

The phase II TACTIC trial prospectively selected patients with KRAS wild-type advanced biliary tract cancer for first-line treatment with panitumumab and combination chemotherapy.

METHODS

Of 78 patients screened, 85 % had KRAS wild-type tumours and 48 were enrolled. Participants received cisplatin 25 mg/m(2) and gemcitabine 1000 mg/m(2) on day 1 and day 8 of each 21-day cycle and panitumumab 9 mg/kg on day 1 of each cycle. Treatment was continued until disease progression, unacceptable toxicity, or request to discontinue. The primary endpoint was the clinical benefit rate (CBR) at 12 weeks (complete response, partial response, or stable disease). CBR of 70 % was considered to be of clinical interest. Secondary outcomes were progression-free survival, time to treatment failure, overall survival, CA19.9 response and safety.

RESULTS

Thirty-four patients had a clinical benefit at 12 weeks, an actuarial rate of 80 % (95 % CI 65-89 %). 46 % had a complete or partial response. Median progression-free survival was 8.0 months (95 % CI 5.1-9.9) and median overall survival 11.9 months (95 % CI 7.4-15.8). Infection accounted for 27 % of the grade 3 or 4 toxicity, with rash (13 %), fatigue (13 %), and hypomagnesemia (10 %) among the more common grade 3 or 4 non-haematological toxicities.

CONCLUSION

A marker-driven approach to patient selection was feasible in advanced biliary tract cancer in an Australian population. The combination of panitumumab, gemcitabine, and cisplatin in KRAS wild-type cancers was generally well tolerated and showed promising clinical efficacy. Further exploration of anti-EGFR therapy in a more selected population is warranted.

Positron emission tomography response evaluation from a randomized phase III trial of weekly nab-paclitaxel plus gemcitabine versus gemcitabine alone for patients with metastatic adenocarcinoma of the pancreas

BACKGROUND

In the phase III MPACT trial, nab-paclitaxel plus gemcitabine (nab-P + Gem) demonstrated superior efficacy versus Gem alone for patients with metastatic pancreatic cancer. We sought to examine the feasibility of positron emission tomography (PET) and to compare metabolic response rates and associated correlations with efficacy in the MPACT trial.

PATIENTS AND METHODS

Patients with previously untreated metastatic adenocarcinoma of the pancreas were randomized 1:1 to receive nab-P + Gem or Gem alone. Treatment continued until disease progression by RECIST or unacceptable toxicity.

RESULTS

PET scans were carried out on the first 257 patients enrolled at PET-equipped centers (PET cohort). Most patients (252 of 257) had ≥2 PET-avid lesions, and median maximum standardized uptake values at baseline were 4.6 and 4.5 in the nab-P + Gem and Gem-alone arms, respectively. In a pooled treatment arm analysis, a metabolic response by PET (best response at any time during study) was associated with longer overall survival (OS) (median 11.3 versus 6.9 months; HR, 0.56; P < 0.001). Efficacy results within each treatment arm appeared better for patients with a metabolic response. The metabolic response rate (best response and week 8 response) was higher for nab-P + Gem (best response: 72% versus 53%, P = 0.002; week 8: 67% versus 51%; P = 0.014). Efficacy in the PET cohort was greater for nab-P + Gem versus Gem alone, including for OS (median 10.5 versus 8.4 months; hazard ratio [HR], 0.71; P = 0.009) and ORR by RECIST (31% versus 11%; P < 0.001).

CONCLUSION

Pancreatic lesions were PET avid at baseline, and the rate of metabolic response was significantly higher for nab-P + Gem versus Gem alone at week 8 and for best response during study. Having a metabolic response was associated with longer survival, and more patients experienced a metabolic response than a RECIST-defined response.

CLINICALTRIALSGOV

NCT00844649.

Clinical trial design and rationale of the Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy With HeartMate 3 (MOMENTUM 3) investigational device exemption clinical study protocol

The HeartMate 3 left ventricular assist system (LVAS; St. Jude Medical, Inc., formerly Thoratec Corporation, Pleasanton, CA) was recently introduced into clinical trials for durable circulatory support in patients with medically refractory advanced-stage heart failure. This centrifugal, fully magnetically levitated, continuous-flow pump is engineered with the intent to enhance hemocompatibility and reduce shear stress on blood elements, while also possessing intrinsic pulsatility. Although bridge-to-transplant (BTT) and destination therapy (DT) are established dichotomous indications for durable left ventricular assist device (LVAD) support, clinical practice has challenged the appropriateness of these designations. The introduction of novel LVAD technology allows for the development of clinical trial designs to keep pace with current practices. The prospective, randomized Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy With HeartMate 3 (MOMENTUM 3) clinical trial aims to evaluate the safety and effectiveness of the HeartMate 3 LVAS by demonstrating non-inferiority to the HeartMate II LVAS (also St. Jude Medical, Inc.). The innovative trial design includes patients enrolled under a single inclusion and exclusion criteria , regardless of the intended use of the device, with outcomes ascertained in the short term (ST, at 6 months) and long term (LT, at 2 years). This adaptive trial design includes a pre-specified safety phase (n = 30) analysis. The ST cohort includes the first 294 patients and the LT cohort includes the first 366 patients for evaluation of the composite primary end-point of survival to transplant, recovery or LVAD support free of debilitating stroke (modified Rankin score >3), or re-operation to replace the pump. As part of the adaptive design, an analysis by an independent statistician will determine whether sample size adjustment is required at pre-specified times during the study. A further 662 patients will be enrolled to reach a total of 1,028 patients for evaluation of the secondary end-point of pump replacement at 2 years.

Two-Year Outcomes of Surgical Treatment of Severe Ischemic Mitral Regurgitation

BACKGROUND

In a randomized trial comparing mitral-valve repair with mitral-valve replacement in patients with severe ischemic mitral regurgitation, we found no significant difference in the left ventricular end-systolic volume index (LVESVI), survival, or adverse events at 1 year after surgery. However, patients in the repair group had significantly more recurrences of moderate or severe mitral regurgitation. We now report the 2-year outcomes of this trial.

METHODS

We randomly assigned 251 patients to mitral-valve repair or replacement. Patients were followed for 2 years, and clinical and echocardiographic outcomes were assessed.

RESULTS

Among surviving patients, the mean (±SD) 2-year LVESVI was 52.6±27.7 ml per square meter of body-surface area with mitral-valve repair and 60.6±39.0 ml per square meter with mitral-valve replacement (mean changes from baseline, -9.0 ml per square meter and -6.5 ml per square meter, respectively). Two-year mortality was 19.0% in the repair group and 23.2% in the replacement group (hazard ratio in the repair group, 0.79; 95% confidence interval, 0.46 to 1.35; P=0.39). The rank-based assessment of LVESVI at 2 years (incorporating deaths) showed no significant between-group difference (z score=-1.32, P=0.19). The rate of recurrence of moderate or severe mitral regurgitation over 2 years was higher in the repair group than in the replacement group (58.8% vs. 3.8%, P<0.001). There were no significant between-group differences in rates of serious adverse events and overall readmissions, but patients in the repair group had more serious adverse events related to heart failure (P=0.05) and cardiovascular readmissions (P=0.01). On the Minnesota Living with Heart Failure questionnaire, there was a trend toward greater improvement in the replacement group (P=0.07).

CONCLUSIONS

In patients undergoing mitral-valve repair or replacement for severe ischemic mitral regurgitation, we observed no significant between-group difference in left ventricular reverse remodeling or survival at 2 years. Mitral regurgitation recurred more frequently in the repair group, resulting in more heart-failure-related adverse events and cardiovascular admissions. (Funded by the National Institutes of Health and Canadian Institutes of Health Research; ClinicalTrials.gov number, NCT00807040.).

CA19-9 decrease at 8 weeks as a predictor of overall survival in a randomized phase III trial (MPACT) of weekly nab-paclitaxel plus gemcitabine versus gemcitabine alone in patients with metastatic pancreatic cancer

Any CA19-9 decline at week 8 and radiologic response by week 8 each predicted longer OS in both treatment arms. In the nab-P + Gem arm, the higher proportion of patients with week 8 CA19-9 decrease [82% (206/252); median OS 13.2 months] than a RECIST-defined response [16% (40/252); median OS 13.7 months] suggests that CA19-9 decline is a predictor of OS applicable to a larger population.

Background

A phase I/II study and subsequent phase III study (MPACT) reported significant correlations between CA19-9 decreases and prolonged overall survival (OS) with nab-paclitaxel plus gemcitabine (nab-P + Gem) treatment for metastatic pancreatic cancer (MPC). CA19-9 changes at week 8 and potential associations with efficacy were investigated as part of an exploratory analysis in the MPACT trial.

Patients and methods

Untreated patients with MPC (N = 861) received nab-P + Gem or Gem alone. CA19-9 was evaluated at baseline and every 8 weeks.

Results

Patients with baseline and week-8 CA19-9 measurements were analyzed (nab-P + Gem: 252; Gem: 202). In an analysis pooling the treatments, patients with any CA19-9 decline (80%) versus those without (20%) had improved OS (median 11.1 versus 8.0 months; P = 0.005). In the nab-P + Gem arm, patients with (n = 206) versus without (n = 46) any CA19-9 decrease at week 8 had a confirmed overall response rate (ORR) of 40% versus 13%, and a median OS of 13.2 versus 8.3 months (P = 0.001), respectively. In the Gem-alone arm, patients with (n = 159) versus without (n = 43) CA19-9 decrease at week 8 had a confirmed ORR of 15% versus 5%, and a median OS of 9.4 versus 7.1 months (P = 0.404), respectively. In the nab-P + Gem and Gem-alone arms, by week 8, 16% (40/252) and 6% (13/202) of patients, respectively, had an unconfirmed radiologic response (median OS 13.7 and 14.7 months, respectively), and 79% and 84% of patients, respectively, had stable disease (SD) (median OS 11.1 and 9 months, respectively). Patients with SD and any CA19-9 decrease (158/199 and 133/170) had a median OS of 13.2 and 9.4 months, respectively.

Conclusion

This analysis demonstrated that, in patients with MPC, any CA19-9 decrease at week 8 can be an early marker for chemotherapy efficacy, including in those patients with SD. CA19-9 decrease identified more patients with survival benefit than radiologic response by week 8.

Socioeconomic status, human papillomavirus, and overall survival in head and neck squamous cell carcinomas in Toronto, Canada

BACKGROUND

Despite universal healthcare in some countries, lower socioeconomic status (SES) has been associated with worse cancer survival. The influence of SES on head and neck cancer (HNC) survival is of immense interest, since SES is associated with the risk and prognostic factors associated with this disease.

PATIENTS AND METHODS

Newly diagnosed HNC patients from 2003 to 2010 (n=2124) were identified at Toronto's Princess Margaret Cancer Centre. Principal component analysis was used to calculate a composite score using neighbourhood-level SES variables obtained from the 2006 Canada Census. Associations of SES with overall survival were evaluated in HNC subsets and by p16 status (surrogate for human papillomavirus).

RESULTS

SES score was higher for oral cavity (n=423) and p16-positive oropharyngeal cancer (OPC, n=404) patients compared with other disease sites. Lower SES was associated with worse survival [HR 1.14 (1.06-1.22), p=0.0002], larger tumor staging (p<0.001), current smoking (p<0.0001), heavier alcohol consumption (p<0.0001), and greater comorbidity (p<0.0002), but not with treatment regimen (p>0.20). After adjusting for age, sex, and stage, the lowest SES quintile was associated with the worst survival only for OPC patients [HR 1.66 (1.09-2.53), n=832], primarily in the p16-negative subset [HR 1.63 (0.96-2.79)]. The predictive ability of the prognostic models improved when smoking/alcohol was added to the model (c-index 0.71 vs. 0.69), but addition of SES did not (c-index 0.69).

CONCLUSION

SES was associated with survival, but this effect was lost after accounting for other factors (age, sex, TNM stage, smoking/alcohol). Lower SES was associated with greater smoking, alcohol consumption, comorbidity, and stage.

Synchronization patterns in geometrically frustrated rings of relaxation oscillators

Diffusively coupled chemical oscillators can exhibit a wide variety of complex spatial patterns. In this paper, we show that a ring of relaxation oscillators diffusively coupled through the inhibitory species leads to remarkable spatiotemporal patterns in the regime where there is a large separation of time scales between the activator and the inhibitor dynamics. The origin of these complex patterns can be traced back to a preponderance of antiphase synchronized states in the space of attractors. We provide an analytical explanation for the existence and stability of the antiphase synchronized states by examining the limit of extreme time scale separation. Numerical results on rings with small numbers of oscillators show that an explosion of patterns occurs for a ring with five oscillators.