Citations

Bioactive surfaces and materials have displayed great potential in a variety of tissue engineering applications but often struggle to completely emulate complex bodily systems. The extracellular matrix (ECM) is a crucial, bioactive component in all tissues and has recently been identified as a potential solution to be utilized in combination with biomaterials. In tissue engineering, the ECM can be utilized in a variety of applications by employing the biochemical and biomechanical cues that are crucial to regenerative processes. However, viable solutions for maintaining the dimensionality, spatial orientation, and protein composition of a naturally cell-secreted ECM remain challenging in tissue engineering. Therefore, this work used soft lithography to create micropatterned polydimethylsiloxane (PDMS) substrates of a three-dimensional nature to control cell adhesion and alignment. Cells aligned on the micropatterned PDMS, secreted and assembled an ECM, and were decellularized to produce an aligned matrix biomaterial. The cells seeded onto the decellularized, patterned ECM showed a high degree of alignment and migration along the patterns compared to controls. This work begins to lay the groundwork for elucidating the immense potential of a natural, cell-secreted ECM for directing cell function and offers further guidance for the incorporation of natural, bioactive components for emerging tissue engineering technologies.

BackgroundChronic exertional compartment syndrome (CECS) is a type of leg pain related to elevated intracompartmental pressure with activity in one or more of the four compartments of the leg. Open fasciotomy is the definitive treatment for CECS but has a reported complication rate of up to 15.7% and return to full activity reported up to 16 weeks. Ultrasound‐guided (USG) fasciotomy of the anterior and lateral compartments has been translated into clinical practice.ObjectiveTo determine the safety and feasibility of a USG fasciotomy of the deep posterior compartment (DPC) and superficial compartment (SPC) of the leg in a fresh‐frozen cadaveric model.DesignProspective, cadaveric laboratory investigation.SettingProcedural skills laboratory at an academic institution.Cadaveric CohortTen fresh‐frozen cadaveric knee‐ankle‐foot specimens from five female and five male donors aged 58 to 93 years (mean 77.4 years) with body mass indexes of 18.1 to 33.5 kg/m2 (mean 25.1 kg/m2).Methods or InterventionsOne experienced operator performed 10 USG DPC and SPC fasciotomies. A clinical anatomist performed dissections of each.Main Outcome MeasuresAchievement of target length and continuity of release was recorded. Target lengths of 10 cm for the superficial posterior compartment (SPC) and 15 cm for the deep posterior compartment (DPC) were established based on previous studies. Tendinous and neurovascular structures were assessed for damage.ResultsNo tendon or neurovascular injuries were observed. In the SPC, target length was achieved in 90% and continuous release was observed in 80%. In the DPC, target length was achieved in 60% and continuity observed in 30%.ConclusionsThese findings suggest that SPC USG fasciotomies using the technique described in this study are feasible, may be safe, and warrant further translational research; however, DPC USG fasciotomies are more challenging and require more technical refinement prior to clinical translation.

11095 Background: Biologic characterization of CTCs is increasingly important in determining metastatic breast cancer (MBC) patient (pt) prognosis and treatment prediction. Combined preliminary results from two earlier metastatic BC NCCTG trials, N0234 & N0336, suggested that the change in CTC mammaglobin (MGB1) gene expression between baseline and two cycles of chemotherapy predicted tumor response (p=0.04). The objectives of this study were to 1) determine CTC gene expression of CK19 and MGB1 before, during, and after treatment in N0436 & N0437 and 2) determine associations between baseline and post-treatment gene expression and treatment response. Methods: CTCs were enriched using CD45-depletion from ∼10ml EDTA blood obtained from metastatic BC pts before, after two cycles, and at end of treatment with either first/second-line irinotecan plus cetuximab (N0436) or first-line paclitaxel poliglumex and capecitabine (N0437). CK19 and MGB1 mRNA levels were determined using quantitative RT-PCR in baseline and serial CTC samples of up to 19 pts from N0436 and 40 pts from N0437. The relative gene expressions were normalized to β2-microglobulin and calibrated to healthy blood using the 2-ΔΔCt algorithm; a value of 2 was defined as positive for the respective marker. Results: CK19+ mRNA was detected in 58% of baseline samples from N0436 (11/19) and N0437 (23/40). MGB1+ mRNA was detected in 32% (6/19) and 38% (15/40) of N0436 and N0437 baseline samples, respectively. CK19+ mRNA was detected in 50% (7/14) and 56% (29/52) of N0436 and N0437 serial CTC samples, respectively. MGB1+ mRNA was detected in 29% (4/14) and 27% (14/52) of N0436 and N0437 serial CTC samples, respectively. Of the 66 serial samples, 27% of samples (18/66) had turned positive from baseline for CK19 or MGB1. CK19 mRNA was detected in 85% (33/39) of MGB1+ mRNA samples but their baseline mRNA levels were not correlated. Conclusions: CK19 mRNA was detected in MBC pts with similar frequencies to the CellSearch imaging system. CK19 was detected at a higher frequency than MGB1. In the majority of cases, MGB1 was co-expressed with CK19. Associations between gene expression and treatment response using Chi-Squared analyses and Cox regression models will be presented. No significant financial relationships to disclose.

9078 Background: A frequently discussed topic at meetings of oncologists is the question of expected clinical outcomes for patients with metastatic melanoma undergoing 1st vs 2nd line systemic therapy. Differing outcomes in these two patient populations could affect interpretation of non-randomized clinical trials involving both patient populations. Some have suggested superior clinical outcome in patients undergoing 2nd line therapy. As there is little data addressing this issue, we sought to answer the question by comparing the clinical outcomes of patients with metastatic melanoma treated on 1st vs 2nd line therapy across clinical trials conducted at our institution. Methods: Data were collected from 10 phase II clinical trials for patients with stage IV melanoma for which Mayo Clinic was the data center. The 10 trials included three categories of treatments: cytotoxic chemotherapy (4), cancer vaccines (4), and biologic agents (2). In all studies, eligibility criteria required: stage IV melanoma, life expectancy >3 months, reasonable hematology and serum chemistry laboratory results, and an ECOG performance status of ≤2. Cox proportional hazards models were fit to assess the relationship between patients' “therapy” status (1st vs 2nd line) and time to events, both overall survival (OS) and progression free survival (PFS), for each treatment category. Results: We identified 318 unique eligible patients across 10 trials. Removed from the analysis were 55 patients (ocular melanoma and/or metastases involving the central nervous system) leaving 263. Cox proportional hazards results demonstrated no differences in PFS or OS for 1st vs 2nd line patients for either “chemotherapy” or “vaccine” treatment regimens. However, patient treated on “biologic” trials as 1st line therapy appeared to demonstrate a PFS advantage over 2nd line treatments (HR=1.98, p-value=0.02). There was a suggestion of an OS benefit for 1st line patients in this category, however, the relationship was not significant (HR=1.77, p=0.07). Conclusions: The presented data suggest that there is no PFS/OS difference in stage IV melanoma patients receiving 1st vs 2nd line therapy (no PFS/OS advantage to patients treated in 2nd line vs. 1st line). No significant financial relationships to disclose.

7003 Background: In younger adults with newly diagnosed acute myeloid leukemia (AML), anthracycline dose intensification during induction may improve complete remission (CR) rates; however, an improvement in overall survival (OS) in a randomized trial has not been demonstrated. This unresolved issue led the ECOG to compare standard dose (SDD) to high-dose daunorubicin (HDD) in induction. Methods: Adult patients with previously untreated AML were randomized to receive either SDD (45 mg/m2/d) or HDD (90 mg/m2/d) each for 3days combined with standard-dose cytarabine (100 mg/m2/d) for 7 days by continuous intravenous infusion. Those achieving a CR were allocated to allogeneic hematopoietic stem cell transplantation (HSCT) or high-dose cytarabine (with or without a single dose of gemtuzumab ozogamicin) prior to autologous HSCT. Intravenous busulfan and cyclophosphamide was the preparative regimen for both allogeneic and autologous HSCT. The primary end point of this study was OS from the time of induction randomization. Results: 633 patients, age 18 to 60 (median 48) years, were entered in this study. There were no differences in patient demographics or disease characteristics between the two groups at presentation. In an intention-to-treat analysis, HDD resulted in a significantly higher CR rate (63.3% vs. 47.7%, p = 0.0003) than SDD. Induction deaths were similar between the two groups (5.4 vs. 5.0%, p = ns). 334 (52.8%) patients entered the consolidation phase. 57.4% of HDD and 48.1% of the SDD patients, received consolidation therapy on study, and 28.7% and 23.1% proceeded to HSCT respectively. Median OS was superior for the HDD (23.7 months) over the SDD (15.1 months) group (p = 0.005). In subgroup analysis, patients with favorable or intermediate-risk cytogenetics or age <55 years benefited from the HDD. Conclusions: We demonstrate for the first time in a prospective randomized trial that intensifying induction therapy through a higher daily anthracycline dose, in the setting of identical intensive consolidation therapy, results in a higher CR rate as well as prolonged OS. In younger AML patients a higher dose of anthracycline in induction should be considered the new standard of care. No significant financial relationships to disclose.

1020 Background: Trastuzumab-containing regimes have dramatically improved outcome of patients with HER2+ breast cancer. Efforts to improve efficacy and tolerability of combination regimens with this monoclonal antibody are important for patient care. Thus, we conducted a multi-institutional phase II study of a triplet combination in patients eligible to receive either first- or second-line treatment for HER2+ metastatic breast cancer (MBC). Methods: A phase II study designed to test that the true confirmed response rate (CRR) was at most 45% versus a true CRR of at least 65% was done (March 2005-June 2008). This design required that at least 25/45 confirmed responses in evaluable patients for the treatment to be considered promising. Patients received capecitabine 825 mg/m2 po (days 1–14), vinorelbine intravenously (IV) 25 mg/m2 days 1 and 8 every 3 weeks and trastuzumab IV 8mg/kg day 1, week 1, and then 6 mg/kg q 3 weeks. Tissue and blood have been collected for future studies on biomarkers. Results: 47 women were accrued, one patient cancelled participation prior to receiving any study drug, and another had a major protocol violation. 45 patients were evaluable and 30 (67%) achieved a confirmed response, (26 patients, 58% had a confirmed partial response and 4 patients, 9% had a confrimed complete response). Median progression free survival was 11.3 months (95% CI 8.4–23.2 months), median overall survival was 27.2 months (95% CI: 26.6-NA months), and among the 30 responders, the median duration of response time was 15.5 months (95% 7.7–26.1 months). The most common grade 3 events include neutropenia 61%, fatigue 13%, skin reaction-hand-foot 11%, and leukopenia 11%. Alopecia was not noted with this regimen. Conclusions: This triplet combination is effective, safe, and is promising in patients with HER2+ MBC. A phase III study should be conducted to compare the best doublet with this triplet combination whether this would lead to better clinical outcomes. [Table: see text]

Background Trans-acting programmed death-ligand 1 (PD-L1) derives from malignant cells in three known forms. High levels of secreted splice variant PD-L1 (sPD-L1), ADAM10/ADAM17-shed sPD-L1, and PD-L1-positive extracellular vesicles (evPD-L1) each predict poor prognosis and limited response to PD-(L)1 checkpoint inhibitors in cancer. To our knowledge, no clinical intervention has reduced any of these circulating forms of extracellular PD-L1. Here, we explore therapeutic plasma exchange (TPE) as a treatment to reduce circulating extracellular PD-L1. Results In patients with melanoma, sPD-L1 levels above 0.277 ng/mL predicted inferior overall survival. In patients undergoing TPE for non-malignant indications, each TPE session removed a mean 70.8% sPD-L1 and 73.1% evPD-L1 detectable in plasma. TPE also reduced total and ADAM10-positive extracellular vesicles. Conclusion Here, we report the first known clinical intervention to remove either sPD-L1 or evPD-L1 from plasma in vivo. TPE reduces plasma sPD-L1 and evPD-L1 in vivo and may have a role in treatment with immunotherapy. TPE may also prove useful in patients with other extracellular vesicle-related conditions.

Background and objectives Thoracic paravertebral blockade is often used as an anesthetic and/or analgesic technique for breast surgery. With ultrasound guidance, the rate of complications is speculated to be lower than when using landmark-based techniques. This investigation aimed to quantify the incidence of pleural puncture and pneumothorax following non-continuous ultrasound-guided thoracic paravertebral blockade for breast surgery. Methods Patients who received thoracic paravertebral blockade for breast surgery were identified by retrospective query of our institution’s electronic database over a 5-year period. Data collected included patient demographics, level of block, type and volume of local anesthetic, occurrence of pleural puncture, occurrence of pneumothorax, evidence of local anesthetic toxicity, and patient vital signs. The incidence of block complications, including pleural puncture, pneumothorax, and local anesthetic toxicity, were ascertained. Results 529 patients underwent 2163 thoracic paravertebral injections. Zero pleural punctures were identified during block performance; however, two patients were found to have a pneumothorax on postoperative chest X-ray (3.6 per 1000 surgeries, 95% CI 0.5 to 13.6; 0.9 per 1000 levels blocked, 95% CI 0.1 to 3.3). There were no cases of local anesthetic systemic toxicity or associated lipid emulsion therapy administration. Conclusions Pneumothorax following non-continuous ultrasound-guided thoracic paravertebral block using a parasagittal approach is an uncommon occurrence, with a similar rate to pneumothorax following breast surgery alone.

INTRODUCTION: As multidisciplinary treatment modalities for rectal cancer continue to evolve, neoadjuvant chemoradiation then surgical resection is a common approach. Robotic-assisted abdominoperineal resection is becoming more prevalent in part because of better visualization and instrument mobility within the pelvis. After abdominoperineal resection, postoperative perineal wound complications remain a significant risk. Pelvic reconstruction lowers this risk, and a pedicled rectus abdominis muscle flap is frequently used to achieve this. Traditional flap harvest requires laparotomy, resulting in violation of both rectus sheaths and a large midline scar. Robotic harvest of the rectus abdominis muscle for pelvic reconstruction after abdominoperineal resection is a novel approach with foreseeable benefits. TECHNIQUE: After completion of abdominoperineal resection, 2 additional trocars are inserted in the lateral abdomen, and the robot is reoriented toward the posterior abdominal wall. The peritoneum and posterior rectus sheath are incised, and dissection is carried superiorly and inferiorly in a sagittal plane to reveal the rectus abdominis muscle. The muscle body is separated from the anterior rectus sheath. Once the inferior epigastric artery is identified, the superior pole of the muscle is transected. Continued lateral dissection ensures flap mobility for placement within the pelvis. After obtaining proper reach, the robot is undocked, and the flap is sutured in place through the perineal defect. RESULTS: After trocar placement and robot repositioning, both the colorectal and plastic surgeons trade places at the console. Robotic flap harvest precludes the need for laparotomy. The anterior rectus sheath remains unviolated and the patient avoids an additional midline scar. The aforementioned benefits of robot-assisted abdominoperineal resection, namely increased visualization and maneuverability, were also found applicable when robotically harvesting this flap. CONCLUSIONS: This technique exemplifies an additional minimally invasive technique for patients pursuing abdominoperineal resection. With knowledge of this novel approach, surgeons can better tailor their operations to benefit the patient.