O050 A ten-year review of methodological trends and outcomes in riskreducing mastectomy and associated reconstruction at a tertiary referral centre

Introduction

Risk-reducing mastectomy (RRM) is the removal of breast tissue to substantially decrease the risk of developing breast cancer in individuals with higher breast cancer susceptibility due to strong family history or genetic mutations. This retrospective study evaluates cases of RRM, and subsequent reconstruction performed at a tertiary referral centre over the last decade, with emphasis on mastectomy and reconstructive trends.

Methods

A retrospective review of all cases of RRM performed between January 2010 and January 2020, divided into two groups corresponding to the first half (group 1) and second half (group 2) of the decade was conducted. Data collected included demographics, genetic test results, family and personal history of breast cancer, co-morbidities, mastectomy type, reconstruction type, surgical histopathology findings and complications.

Results

A total of 167 patients (group 1=76, group 2=91) underwent RRM, with a significant increase in cases of RRM despite negative genetic test results (p=0.047). The proportion of nipple sparing techniques for RRM compared to more traditional skin-sparing techniques. Concomitantly, post-RRM reconstruction has progressively become solely implant-based, to coincide with a rise in ADM usage. This is consistent with national trends towards fewer complex autologous procedures.

Take-home message

Emergent trends in risk-reducing mastectomy and reconstructive techniques are occurring against a background of broadened indications for RRM and more frequent patient requests for RRM in the absence of any documented pathogenic gene mutation. As breast surgery continues to evolve, it is important to evaluate specific trends such as more conservative forms of mastectomy and novel techniques/devices for breast reconstruction to ensure optimal patient care and levels of satisfaction.

Survival of patients with neuroblastoma before versus after reduction of therapy due to the change in age cut-off from 12 to 18 months in Children’s Oncology Group (COG) risk stratification

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Background: In 2006, COG reclassified subgroups of toddlers diagnosed with neuroblastoma from high-(HR) to intermediate-risk (IR), when the age cut-off for increased risk was raised from 365 days (12 mo) to 547 days (18 mo) (London, J Clin Onc 2005). The aim of this retrospective study was to determine if excellent outcome was maintained after a reduction of therapy. Methods: Children < 3 yrs old at diagnosis, enrolled on a COG biology study from 1990-2018, were eligible (n = 9,189). Therapy was reduced for two “cohorts of interest” based on the age cut-off change: 365-546 days old with INSS stage 4, MYCN not amplified, favorable INPC, hyperdiploid tumors (12-18mo/Stage4/FavBiology); and, 365-546 days old with INSS stage 3 tumors with non-amplified MYCN and unfavorable INPC (12-18mo/Stage3/NotAmp/UnfavINPC). Log rank tests compared event-free (EFS) and overall survival (OS) curves. Results: In the cohorts of interest, patient (pt) characteristics were similar for ≤2006 vs > 2006. For 12-18mo/Stage4/FavBiology, 5-year EFS and OS (± std error) before (≤2006; n = 40) versus after (> 2006; n = 55) the reduction in therapy were similar: 89±5.1% versus 87±4.6% (p = 0.7), and 89±5.1% versus 94±3.2% (p = 0.4), respectively (Table). For 12-18mo/Stage3/NotAmp/UnfavINPC, the 5-year EFS and OS were both 100%, before (n = 6) and after (n = 4) 2006. For the combined cohorts for ≤2006 versus > 2006, EFS and OS were 91±4.4% versus 88±4.3% (p = 0.6), and 91±4.5% versus 95±2.9% (p = 0.5), respectively. Within HR pts diagnosed ≤2006, EFS/OS were 91±4.4%/91±4.5% for (12-18mo/Stage4/FavBiology plus 12-18mo/Stage3/NotAmp/UnfavINPC) vs 38±1.3%/43±1.3% for all other HR pts < 3 yrs old (p < 0.0001; Table). Within IR pts diagnosed > 2006, EFS/OS were 88±4.3%/95±2.9% for (12-18mo/Stage4/FavBiology plus 12-18mo/Stage3/NotAmp/UnfavINPC) vs 88±0.9%/95±0.6% for all other IR pts < 3 yrs old (p = 0.9). Conclusions: Our 19 year study demonstrates that excellent outcome is maintained among toddlers with Stage4/FavBiology and Stage3/Not Amp/Unfav INPC neuroblastoma with a significant reduction of therapy from high- to intermediate-risk treatment. Importantly, pts were likely spared acute toxicity and late effects known to be associated with HR therapy. Efforts to identify additional pt cohorts who may not require HR therapy to achieve long-term survival are critical to improve the long-term health of children with neuroblastoma. [Table: see text]

Second Paediatric Strategy Forum for anaplastic lymphoma kinase (ALK) inhibition in paediatric malignancies: ACCELERATE in collaboration with the European Medicines Agency with the participation of the Food and Drug Administration

The first (2017) and sixth (2021) multistakeholder Paediatric Strategy Forums focused on anaplastic lymphoma kinase (ALK) inhibition in paediatric malignancies. ALK is an important oncogene and target in several paediatric tumours (anaplastic large cell lymphoma [ALCL], inflammatory myofibroblastic tumour [IMT], neuroblastoma and hemispheric gliomas in infants and young children) with unmet therapeutic needs. ALK tyrosine kinase inhibitors have been demonstrated to be active both in ALK fusion-kinase positive ALCL and IMT. ALK alterations differ, with fusions occurring in ALCL, IMT and gliomas, and activating mutations and amplification in neuroblastoma. While there are many ALK inhibitors in development, the number of children diagnosed with ALK driven malignancies is very small. The objectives of this ALK Forum were to (i) Describe current knowledge of ALK biology in childhood cancers; (ii) Provide an overview of the development of ALK inhibitors for children; (iii) Identify the unmet needs taking into account planned or current ongoing trials; (iv) Conclude how second/third-generation inhibitors could be evaluated and prioritised; (v) Identify lessons learnt from the experience with ALK inhibitors to accelerate the paediatric development of other anti-cancer targeted agents in the new regulatory environments. There has been progress over the last four years, with more trials of ALK inhibitors opened in paediatrics and more regulatory submissions. In January 2021, the US Food and Drug Administration approved crizotinib for the treatment of paediatric and young adult patients with relapsed or refractory ALCL and there are paediatric investigation plans (PIPs) for brigatinib and for crizotinib in ALCL and IMT. In ALCL, the current goal is to investigate the inclusion of ALK inhibitors in front-line therapy with the aim of decreasing toxicity with higher/similar efficacy compared to present first-line therapies. For IMT, the focus is to develop a joint prospective trial with one product in children, adolescents and adults, taking advantage of the common biology across the age spectrum. As approximately 50% of IMTs are ALK-positive, molecular analysis is required to identify patients to be treated with an ALK inhibitor. For neuroblastoma, crizotinib has not shown robust anti-tumour activity. A focused and sequential development of ALK inhibitors with very good central nervous system (CNS) penetration in CNS tumours with ALK fusions should be undertaken. The Forum reinforced the strong need for global academic collaboration, very early involvement of regulators with studies seeking possible registration and early academia-multicompany engagement. Innovations in study design and conduct and the use of 'real-world data' supporting development in these rare sub-groups of patients for whom randomised clinical trials are not feasible are important initiatives. A focused and sequenced development strategy, where one product is evaluated first with other products being assessed sequentially, is applicable for ALK inhibitors and other medicinal products in children.

Abstract SY09-03: PROFYLEing Cancer for KiCS: The Canadian Pediatric Precision Oncology Initiative

Each year, approximately 4300 children, adolescents and young adults (CAYA) are diagnosed with cancer. One-third of these patients present with metastatic disease, develop refractory disease or relapse. For these patients, the likelihood of survival remains grim and essentially unchanged in more than three decades. Precision Oncology for Young PeopLE (PROFYLE) is a pan-Canadian, interdisciplinary program that was built on the foundation of three major sequencing efforts in Vancouver (PedsPOG), Toronto (KiCS) and Montreal (TRICEPS) for children with hard-to-treat cancer. Since its inception in 2017, over 700 patients have had complete NGS of paired blood-tumor samples with a goal to not only develop a national precision oncology pipeline, but also to determine the frequency and spectrum of molecular targets for novel therapies and other clinically actionable findings. During this presentation, both the process as well as current findings will be presented and plans for the future will be outlined.

Citation Format: David Malkin, Jason N. Berman, Jennifer A. Chan, Avram Denburg, Rebecca Deyell, David Eisenstadt, Conrad Fernandez, Stephanie Grover, Abha Gupta, Cynthia Hawkings, Meredith Irwin, Nada Jabado, Steven Jones, Daniel Morgenstern, Michael Moran, Rod Rasesekh, Adam Shlien, Daniel Sinnett, Poul Sorensen, Patrick Sullivan, Michael Taylor, Anita Villani, Jim Whitlock. PROFYLEing Cancer for KiCS: The Canadian Pediatric Precision Oncology Initiative [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr SY09-03.

Abstract B07: Prospective germline next-generation sequencing in pediatric patients with neuroblastoma identifies frequent alterations in genes involved in DNA damage repair

Background: The role of germline ALK and PHOX2B variants in genetic predisposition to neuroblastoma (NB) is well established; however, alterations in genes associated with other syndromes, including RASopathies, Fanconi anemia, and Li-Fraumeni, have also been detected. Emerging data suggest potential roles for DNA damage repair (DDR) pathway genes in NB predisposition. The use of next-generation sequencing (NGS) technologies facilitates the unbiased detection of both known and novel germline variants.

Methods: Patients (pts) with newly diagnosed and relapsed malignancies, including 43 NB pts, were referred to our institutional pediatric oncology NGS study to sequence germline DNA, tumor DNA, and RNA. Germline DNA was sequenced using a custom pediatric cancer panel (Agilent Sure Select capture technology) targeting 15,000 exons across 864 genes (1000x coverage). Variant pathogenicity was classified according to ACMG (American College of Medical Genetics and Genomics) criteria and evaluated at multidisciplinary molecular tumor boards. Rare variants of uncertain significance (VUS) with supportive corresponding somatic data, patient phenotypes, literature, and/or in-silico functional analyses were termed “Variants of uncertain significance with limited evidence for pathogenicity” (VUS-LEP).

Results: Analyses have been completed for 41/43 enrolled NB pts. Patient history was retrospectively categorized as “high genetic predisposition risk” (HGPR) in 14/41 pts based on ≥1 of the following criteria: (1) family history of NB and/or significant family history of other cancer(s); (2) patient with NB and another metachronous or synchronous malignancy; (3) NB with congenital abnormalities; (4) multifocal NB. Germline pathogenic (P), likely pathogenic (LP) variants, or VUS-LEP in a known cancer predisposition gene were identified in 6/14 HGPR pts (43%), predominantly in DDR-related genes (PALB2, BRCA1/CHEK2, CHEK2/PALB2, NF1, DICER1, MITF). Of note, no ALK or PHOX2B germline variants were identified for the five pts with NB family history. For the 27 non-HGPR pts, germline P, LP variants or VUS-LEP in DDR genes were most prevalent and detected in 8/27 pts (30%), in genes such as BAP1, BARD1 (n=2), BLM, BRCA2, CHEK2, RAD51, RAD51D/NBN. In this non-HGPR population, we also identified a germline P TP53 variant (n=1), a LP FH variant (n=1) as well as additional germline VUS-LEPs in EZH2 (n=1) and ERCC2 (n=1).

Conclusion: Prospective sequencing identified frequent germline variants in NB pts, predominantly in genes involved in DDR and homologous recombination, regardless of classification as HGPR. We intend to complete and report somatic characterization of the tumors, with a focus on mutational signatures and 11q loss encompassing ATM. Our findings may have implications for future targeted treatment recommendations (e.g., PARP inhibitors) as well as for appropriate genetic counseling for pts and families.

Citation Format: Sarah Cohen-Gogo, Karin Langenberg-Ververgaert, Anita Villani, Winnie Lo, Ted Young, Nisha Kanwar, Scott Davidson, Nathaniel Anderson, Bailey Gallinger, Mehdi Layeghifard, Larissa Waldman, Daniel Morgenstern, Ledia Brunga, Stephen Meyn, David Malkin, Adam Shlien, Meredith Irwin. Prospective germline next-generation sequencing in pediatric patients with neuroblastoma identifies frequent alterations in genes involved in DNA damage repair [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr B07.

Segmental chromosome aberrations and clinical response impact outcome of inss stage III patients ≥18 months with unfavorable histology and without MYCN amplification: A Children’s Oncology Group (COG) report

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Background: Patients with INSS stage III neuroblastoma represent a heterogeneous population with respect to disease presentation and prognosis and controversy exists regarding the most effective treatment algorithms. Patients ≥18 months of age with INSS Stage 3 tumors that are unfavorable histology (UH) and MYCN-non-amplified ( MYCN-NA) represent a small cohort of patients with an outcome intermediate of those with favorable histology tumors and MYCN amplified tumors. The presence of Segmental Chromosome Aberrations (SCA) may predict outcome; however, their impact specifically in this cohort of patients has not been reported. Methods: Eligible patients enrolled on therapeutic protocols A3973 (n=34), ANBL0532 (n=27), and biology protocol ANBL00B1 (n=101 with 29 treated on A3973/ANBL0532) with stage III disease, MYCN–NA, UH and age ≥18 months at diagnosis were analyzed. Copy number alterations and loss of heterozygosity (LOH) for relevant loci were scored for gains/losses by two independent reviewers. Results: The 5-year EFS/OS for children ≥18 months with stage III, MYCN–NA, UH disease treated on A3973 and ANBL0532 was 73.0±8.1%/87.9±5.9% and 61.4±10.2%/ 73.0±9.2%, respectively, with no statistical differences in EFS or OS between the two cohorts (p=0.1286 and p=0.2180, respectively). In the combined cohort of patients enrolled on A3973 and ANBL0532, statistically significant differences were found (p(s) <0.0001) in patients with CR/VGPR (n=39) and PR (n=13) having better outcomes than <PR (n=5) (5-year EFS: 74.0±7.6% vs. 75.0±12.5% vs. 0%; 5-year OS: 84.4±6.2% vs. 100% vs. 20.0±17.9%). Subjects with chromosome 11q loss/LOH had an inferior outcome in comparison to those without 11q loss/LOH (10-year EFS: 44.4+/-24.1% vs. 78.1+/-9.4%, p=0.01; 10-year OS: 62.4+/-15.9% vs. 85.9+/-7.8%, p=0.02)). Patients with 1p loss/LOH and 2p gain also showed trend towards worse event-free survival (p=0.086 and p=0.088, not statistically significant) but not in overall survival. Conclusions: High-risk therapy that included single myeloablative therapy led to an 81.6±5.3%5-year OS in patients ≥18 months with UH and MYCN–NA stage III neuroblastoma. Response to therapy is a powerful predictor of survival and the presence of chromosome 11q loss/LOH is also associated with inferior outcomes. These patients should continue to be treated on high-risk clinical trials.

Randomized phase II trial of MIBG versus MIBG/vincristine/irinotecan versus MIBG/vorinostat for relapsed/refractory neuroblastoma: A report from the New Approaches to Neuroblastoma Therapy Consortium

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Background: 131I-metaiodobenzylguanidine (MIBG) remains one of the most active agents for neuroblastoma. It is not clear if putative radiation sensitizers improve upon this activity. The primary aim of this trial was to identify the MIBG treatment regimen with highest response rate among: MIBG monotherapy (Arm A); MIBG/Vincristine/Irinotecan (Arm B); MIBG/Vorinostat (Arm C). The secondary aim was to compare toxicity across arms. Methods: We conducted a multicenter, randomized phase II trial. Patients 1-30 years with relapsed/refractory high-risk neuroblastoma were eligible with at least one MIBG-avid site and adequate autologous stem cells (ASCs). All patients received MIBG 18 mCi/kg on Day 1 and ASC on day 15. Patients on Arm A received only MIBG; patients on Arm B also received vincristine (2 mg/m2) IV on Day 0 and irinotecan (50 mg/m2) IV daily on Days 0-4; patients on Arm C also received vorinostat (180 mg/m2) orally once daily on days -1 to 12. The primary endpoint was response after one course according to NANT response criteria. The trial was designed as a pick-the-winner study with a maximum of 105 eligible and evaluable patients to ensure an 80% chance that the arm with highest response rate is selected, if that response rate is at least 15% higher than the other arms. Results: 114 patients enrolled. Three patients were ineligible and 6 eligible patients never received MIBG, leaving 105 eligible and evaluable patients (36 Arm A; 35 Arm B; and 34 Arm C; 55 boys; median age 6.5 years). 9 patients had received prior MIBG monotherapy, 65 prior irinotecan, and 7 prior vorinostat. After one course, the response rates (Partial Response or better) on Arms A, B, and C were 17% (95% CI 7-33%), 14% (5-31%), and 32% (18-51%). An additional 4, 4, and 7 patients met NANT Minor Response criteria [partial response in one disease category (e.g., bone marrow) and stable disease in other categories] on Arms A, B, and C, respectively. On Arms A, B, and C, rates of any grade 3+ non-hematologic toxicity were 19%, 49% and 32%; rates of grade 3+ diarrhea were 0%, 11%, 0%; and rates of grade 3+ febrile neutropenia were 6%, 11%, and 0%. Conclusions: The combination of vorinostat/MIBG had the highest response rate, with manageable toxicity. Vincristine and irinotecan do not improve the response rate to MIBG and are associated with increased toxicity. These data provide response rates for MIBG monotherapy in a contemporary patient population assessed with current response criteria. Clinical trial information: NCT02035137.

Final analysis of phase I study of ceritinib in pediatric patients with malignancies harboring activated anaplastic lymphoma kinase (ALK)

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Background: Activation of anaplastic lymphoma kinase has been detected in several pediatric malignancies, including anaplastic large-cell lymphoma (ALCL), inflammatory myofibroblastic tumor (IMT), neuroblastoma and others. Preliminary findings from this phase 1, multicenter, dose-escalation study (NCT01742286) indicated a Maximum Tolerated Dose (MTD)/Recommended Dose for Expansion (RDE) of the potent oral ALK inhibitor ceritinib to be 510 mg/m2 (fasted) and 500 mg/m2 (fed) in pediatric patients (pts). Here, we report final safety, pharmacokinetics (PK) and efficacy results. Methods: Children aged ≥1 to <18 years with advanced, mostly pretreated, ALK-aberrant malignancies were enrolled in this study. Dose escalation was conducted to determine the MTD/RDE of ceritinib (primary objective), in both fasted and fed states, following which pts entered an expansion phase to evaluate safety, tolerability, and efficacy at the MTD/RDE. Secondary objectives were evaluation of safety, PK, and efficacy (overall response rate [ORR], duration of response [DOR] and progression-free survival [PFS]). Results: A total of 83 pts (median age, 8 years) with ALK-aberrant malignancies were enrolled into dose-escalation (n = 40) and expansion (n = 43) study periods. Of these, 55 pts (neuroblastoma, n = 30; IMT, n = 10; ALCL, n = 8; others, n = 7) were treated with ceritinib at MTD/RDE (510 mg/m2 [fasted], n = 13; 500 mg/m2 [fed], n = 42). Systemic exposure of ceritinib between the two doses was comparable, so data were pooled for efficacy assessment. The ORRs (95% CI) were 75% (34.9-96.8) for pts with ALCL, 70% (34.8-93.3) for IMT and 20% (7.7-38.6) for neuroblastoma. The median DOR was 15 months (95% CI: 5.8, 22.2) for the 6/30 pts with neuroblastoma who had confirmed CR or PR treated at fasted/fed MTD/RDE. Median DOR was not reached for those with ALCL and IMT. Most common adverse events (AEs) (N = 83; all-grades, all-causality, ≥50% of pts): vomiting (86.7%), diarrhea (78.3%), increased ALT (65.1%), increased AST (59.0%), nausea (56.6%), and abdominal pain (50.6%). Grade 3/4 AEs were observed in 80.7% of pts (mostly transaminase elevations) and were manageable. Six pts (7.2%) were discontinued from ceritinib due to a grade 3/4 AE (mostly transaminase elevation). Conclusions: Substantial activity was observed with ceritinib at the RDE in pts with IMT, ALCL and heavily pretreated neuroblastoma. The toxicity profile of ceritinib in children was manageable and similar to that previously reported in adults. Clinical trial information: NCT01742286.

The ganglioside GD2 as a circulating tumor biomarker for neuroblastoma

BACKGROUND

G_D2 is a ganglioside that is ubiquitously expressed in the plasma membrane of neuroblastoma and is shed into the circulation.

PROCEDURE

G_D2 was measured with a high-pressure liquid chromatography/tandem mass spectrometry assay in serum or plasma from 40 children without cancer (controls) and in biobanked samples from 128 (73 high-risk) children with neuroblastic tumors at diagnosis, 56 children with relapsed neuroblastoma, 14 children with high-risk neuroblastoma after treatment, and 8 to 12 children each with 10 other common childhood cancers at diagnosis.

RESULTS

The C₁₈ (18 carbon fatty acid) lipoform was the predominant circulating form of G_D2 in controls and in patients with neuroblastoma. The median concentration of G_D2 in children with high-risk neuroblastoma at diagnosis was 167 nM (range, 16.1-1060 nM), which was 30-fold higher than the median concentration (5.6 nM) in controls. G_D2 was not elevated in serum from children with the differentiated neuroblastic tumors, ganglioneuroma (n = 10) and ganglioneuroblastoma-intermixed subtype (n = 12), and in children with 10 other childhood cancers. G_D2 concentrations were significantly higher in serum from children with MYCN-amplified tumors (P = 0.0088), high-risk tumors (P < 0.00001), International Neuroblastoma Staging System (INSS) stage 4 tumors (P < 0.00001), and in children who died (P = 0.034).

CONCLUSIONS

Circulating G_D2 appears to be a specific and sensitive tumor biomarker for high-risk/high-stage neuroblastoma and may prove to be clinically useful as a diagnostic or prognostic circulating tumor biomarker. G_D2 will be measured prospectively and longitudinally in children enrolled on a high-risk neuroblastoma treatment trial to assess its ability to measure response to treatment and predict survival.

Abstract 3106: Targeting vitamin D signalling in metastatic neuroblastoma

Background: Neuroblastoma (NB) is the most common extra-cranial solid tumor and the most frequent cause of cancer-related deaths in children. More than half of patients with NB have metastases and their survival is &lt;50%, and only 5% after relapse. Currently, there are no therapies that specifically target metastatic NB and there is a lack of NB models that recapitulate the sites and burden of metastases observed in patients.

Methods: To study metastatic NB, we have developed a mouse model using in vivo selection of SKNAS cells that metastasize following intra-cardiac injection. We isolated subpopulations from bone and brain with enhanced metastatic properties and compared their gene expression profiles to those of the parental SKNAS cells. Using Connectivity Map (CMap) analyses, we identified drugs that were predicted to change the gene expression in the metastatic subpopulations to a profile that is similar to that of parental cell lines.

Results: Calcipotriol, a synthetic analogue of vitamin D, was identified from the CMap analysis to be a potentially selective agent for metastatic NB cell lines. In comparison to the parental cells, treatment of the metastatic subpopulations with calcipotriol resulted in reduced proliferation. Furthermore, calcipotriol sensitivity was reduced in metastatic cells with a knockout of vitamin D receptor (VDR) suggesting its effect is on-target. In contrast to the parental cells, following calcipotriol treatment metastatic subpopulations did not exhibit an increase in protein levels of CYP24A1, the enzyme that metabolizes vitamin D, suggesting a potential mechanism for the differential sensitivity of parental and metastatic cells. Calcipotriol treatment also reduced levels of hippo pathway effectors, YAP and TAZ, which we previously reported to play a role in mediating the metastatic phenotype of the isolated subpopulations. Additionally, metastatic cells that were pre-treated with calcipotriol showed reduced migration in a transwell assay whereas the migration potential of parental cells was not affected. Furthermore, RASSF2, an upstream regulator of the hippo pathway, was identified to be upregulated in a VDR-dependent manner after calcipotriol treatment in the metastatic subpopulations indicating a possible mechanistic link for the effects of calcipotriol on the hippo pathway in these metastatic cells.

Conclusions: Calcipotriol was identified to be more effective against metastatic NB subpopulations in vitro and this may be in part due to defects in CYP24A1 induction in these metastatic cells. Our data also suggests a novel link between VDR, the hippo pathway and metastasis in NB. Further experiments are required to determine the role of VDR, mechanism of action of calcipotriol in selectively inhibiting growth of metastatic NB cells.

Citation Format: Yagnesh Ladumor, Bo Kyung Alex Seong, Robin Hallett, Teresa Adderley, Yingying Wang, Lynn Kee, David Kaplan, Meredith Irwin. Targeting vitamin D signalling in metastatic neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3106.

Abstract 3123: Targeting SHP2 and RAS MAPK pathway in neuroblastoma

Introduction: Neuroblastoma (NB), the most common pediatric extra-cranial solid tumor, recurs in &gt;50% of patients who present with metastases. Strategies to treat relapsed NB, which is often fatal, include targeting relapse-specific signaling pathways. Recently, sequencing studies have revealed that 78% of mutations detected in relapse samples are predicted to activate the RAS-MAPK pathway, suggesting there may be opportunities to pharmacologically target this pathway to treat recurrent NB.

Experimental Design: Our lab previously reported that the PTPN11-encoded tyrosine phosphatase SHP2 is an activator of the RAS pathway, and pharmacologic inhibition of SHP2 inhibited glioblastoma growth in vivo. To determine whether inhibiting SHP2 in NB would impact tumor growth we treated a panel of NB cells with diverse genetic backgrounds, including mutations in NRAS, with different SHP2 inhibitors (SHP099 and II-B08) alone and in combination with additional drugs that target RAS-MAPK signaling.

Results: In comparison to NB cell lines harboring endogenous NRAS mutations (NRASmt), cells with NRAS wild-type (NRASwt) were more sensitive to SHP2 inhibitors. In addition, NRASwt cells engineered to overexpress NRASmt were more resistant to SHP099 than cells with endogenous or overexpressed NRASwt, as demonstrated by higher levels of proliferation, increased survival, and diminished apoptosis. Furthermore, SHP099 effectively inhibited SHP2 in both NRASwt and NRASmt cells, but only failed to inactivate the downstream RAS effector ERK1/2 in NRASmt cells, suggesting that SHP099 treatment alone is ineffective in cells harboring NRAS mutations. To determine whether SHP099 resistance in NRASmt cells could be overcome with combination strategies, sensitive and resistant NB cells were treated with SHP2 inhibitors alone or in combination with other RAS-MAPK pathway inhibitors (vemurafenib, trametinib and ulixertinib). Interestingly, in comparison to SHP099 or II-B08 alone, all three combinations significantly reduced survival and IC50 values in both NRASwt and NRASmt cells. Using the Bliss independence model we determined all three combinations were synergistic.

Conclusions: Our studies demonstrate that NRAS mutations are associated with resistance to SHP2 inhibitors, and that in certain tumors, based on the genetic status of RAS-MAPK-SHP2 signaling components, combinations of drugs targeting this pathway could be effective strategies for relapsed NB.

Citation Format: Ivette Valencia-Sama, Teresa Adderley, Lynn Kee, Gabriella Christopher, Yoshihito Kano, Michael Ohh, Meredith Irwin. Targeting SHP2 and RAS MAPK pathway in neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3123.

A revised Children's Oncology Group (COG) neuroblastoma risk classification system: Report from the COG biology study ANBL00B1

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Background: The COG risk classification system previously used the International Neuroblastoma Staging System (INSS). The pre-treatment INRG staging system (INRGSS) has been adopted internationally, requiring integration of INRGSS with known prognostic biological and clinical characteristics to evaluate outcomes and assess whether this incorporation will require revision to the established COG risk classifier. Methods: 4,037 newly diagnosed neuroblastoma patients were enrolled on COG ANBL00B1 between 2006-2014. Staging per the INSS and INRGSS was determined. Tumor biological and histologic features, including MYCN status [amplified (A) versus not amplified (NA)], ploidy, histology, and segmental chromosome aberrations (SCA) including 1p and 11q LOH, were assessed centrally. Survival analyses were performed to identify independent prognostic factors and to calculate event-free and overall survival (EFS, OS) for combinations of variables used to determine risk group assignments according to COG and INRG classification templates. Results: Using the original COG risk classifier 1,309 low (LR), 992 intermediate (IR) and 1,736 high-risk (HR) patients were identified with 5-year EFS of 91.4±2.1%, 84.3±2.9%, 45.2±3.1%, and OS of 98.1±1.0%, 94.0±1.9%, 54.1±3.0%, respectively. Outcomes based on combinations of clinical and biological prognostic factors were determined and compared for subsets of patients according to the COG (version1) and INRG risk classification systems to develop a revised COG risk classifier that incorporates the INRGSS (version 2, subset shown in table). Conclusions: Use of INRGSS requires a revision to the COG risk classifier. By combining INRGSS and presence of SCA together with age, MYCN status, ploidy, and histology to determine outcome of patients treated with modern era therapies, we developed a revised risk classification system to inform therapy and COG clinical trial eligibility. Clinical trial information: NCT00904241. [Table: see text]

An International Survey Evaluating Factors Influencing the Use of Total Intravenous Anaesthesia

The purpose of this study was to evaluate factors influencing the use of propofol-based total intravenous anaesthesia (TIVA) since despite TIVA being a well-established technique, it is used far less frequently than volatile anaesthesia. Questions were formulated after reviewing the literature for perceived disadvantages of TIVA and meeting with a focus group consisting of both senior and junior anaesthestists from our department. Once the survey had been formulated, specialist anaesthetists from professional colleges and societies from several countries were invited to complete the survey on an electronic web-based platform to allow evaluation of the respondent's rating of the importance of a range of factors in their decision not to use TIVA for a particular case. Basic descriptive statistics were determined using SPSS statistical software, while graphical depictions of data were handled using R for statistical analysis. A total of 763 survey responses were included in the final analysis and stratified according to the frequency of TIVA use. Among the infrequent users, issues such as additional effort, institutional preference, lack of real-time monitoring of propofol concentration, risk of missing drug delivery failure and increased turnaround time were among the top reasons mentioned. Interestingly, these issues were considered far less important among the frequent users when not choosing TIVA. We concluded that frequent and infrequent users respond quite differently to similar technical TIVA-related factors. Non-technical factors may play an important role in the infrequent user's decision not to use TIVA for a particular case.

Abstract NG05: TP53-mediated human cancer susceptibility is defined by epigenetic dysregulation of microRNA-34A

Mutations in the TP53 tumor suppressor gene are the most common genetic aberrations across all human cancers. Germline TP53 mutations are also the hallmark genetic event in Li-Fraumeni syndrome (LFS), a highly penetrant human cancer susceptibility syndrome, conferring a predisposition to developing early-onset breast cancer, leukemias, bone and soft tissue sarcomas, brain tumors of various histologies, adrenocortical carcinomas, and a wide range of other malignancies. Although the link between mutant TP53 and human cancer is unequivocal, the mechanism by which this genetic aberration predisposes an individual to cancer remains to be elucidated.

To address this gap, we surveyed the epigenome and describe herein the largest systematic analysis of DNA methylation in patients harboring germline TP53 mutations and TP53 wild-type individuals. Specifically, we performed genome-wide methylation analyses of peripheral blood leukocyte DNA in germline TP53 mutation carriers (n=72) and TP53 wild-type individuals who developed histologically comparable cancers (n=111). Targeted bisulfite pyrosequencing was performed on peripheral blood DNA in a validation cohort (n=76), and candidate sites were further evaluated in primary tumors from LFS patients.

The differential methylation analysis demonstrates that in 183 patients, distinct DNA methylation signatures are associated with deleterious TP53 mutations. TP53 mutation-associated DNA methylation marks occur in genomic regions harboring known p53 binding sites and within genes encoding p53 pathway proteins. Moreover, loss-of-function TP53 mutations are significantly associated with differential methylation at the locus encoding miR-34A-a key component of the p53 regulatory network (adjusted p-value=3.1X10-15)-and validated in an independent patient cohort (n=76, 1.9X10-8). Targeted sequencing demonstrates that miR-34A is inactivated by hypermethylation across many different histologic types of primary tumors from LFS patients, such as brain tumors, osteosarcomas, rhabdomyosarcomas, and adrenocortical carcinomas. miR-34A promoter hypermethylation in tumors is also associated with decreased overall survival in a cohort of 29 patients with choroid plexus carcinomas, a characteristic LFS tumor (p&lt;0.05). The relationship between miR-34A hypermethylation and TP53 mutation was further validated in sporadic cancers, using the publicly available TCGA dataset. This demonstrates the robustness of this correlation and the applicability of these findings to other cancer contexts.

This study refines the role of epigenetics in a cancer predisposition syndrome and is the first to implicate a microRNA, miR-34A, in human cancer susceptibility and provides a repository of genomic regions of deregulated methylation in the context of dysfunctional TP53. These findings suggest that deregulated DNA methylation at defined genomic loci may be an important hallmark of TP53-mediated cancer susceptibility. The most striking finding from this study is the relative miR-34A promoter hypomethylation at two adjacent CpG sites in peripheral blood from TP53 mutation carriers, confirmed in two independent cohorts and shown to cosegregate with TP53 mutations in LFS families. This result is remarkable since miR-34A is a central microRNA in the p53 network and the first microRNA identified as a direct proapoptotic target of the p53 pathway.

The detection of miR-34A promoter hypomethylation in TP53 mutant cells that have not undergone malignant transformation supports a putative model whereby wild-type p53 may influence methylation patterns at this locus. In particular, in nontransformed cells that do not harbor mutations in TP53, wild-type p53 may be recruited to the miR-34A locus and sustain hypermethylation. We have performed a series of in vitro studies on primary patient-derived lymphoblastoid cell lines to corroborate this model. Conversely, in the setting of loss-of-function or deleterious mutations in TP53, mutant p53 may not able to maintain hypermethylation of the miR-34A promoter, leading to upregulation of miR-34A. Owing to the known redundant cellular roles of p53 and miR-34A, upregulation of miR-34A may be beneficial to cells harboring mutant p53 by supplementing the necessary basal tumor suppressive function that is lost when p53 is mutated. This mechanism may serve to guard against mutant p53, even when the wild-type allele remains. Accordingly, this may explain why miR-34A promoter hypermethylation is characteristic of TP53-mutant tumors that lack wild-type p53 because this microRNA serves a critical role in cell maintenance, and its loss may cooperate with other genetic and/or epigenetic events to drive malignancy. It is therefore not surprising that, akin to p53, somatic miR-34A deregulation is pervasive in human cancer and miR-34A inactivation by focal deletion or promoter hypermethylation has been reported in the literature to occur in a multitude of human malignancies. The precise mechanisms of how the miR-34A promoter undergoes somatic epimutation in tissues remains to be elucidated, and likely various pathways may converge to yield this outcome in different tissues.

Given the high frequency of TP53 mutations in human malignancies, the relationship between mutant p53 and miR-34A has strong implications for the targeting of miR-34A in cancer. Encouragingly, studies have demonstrated in vivo the utility of miR-34A-based therapies in cancer, including intratumor or systemic delivery of lipid-formulated synthetic miR-34A.

To further probe these intriguing findings, we conducted mechanistic studies aimed at functionally interrogating the the miR-34A-p53 axis. We utilized in vitro-based assays to modulate miR-34A levels in primary patient-derived fibroblast cell lines, and subsequently performed by RNA-sequencing of the transcriptional responses. Our results uncover a number of novel cellular roles for miR-34A in cell maintenance. Significantly, the transcriptional response to miR-34A inhibition revealed that this microRNA may be a crucial switch that can lead to numerous changes to noncoding RNA networks as well as known p53 pathways. Markedly increased expression of key components of the U12 (minor) spliceosome occurs when miR-34A expression is diminished, thereby identifying a novel putative role of miR-34A in modulating transcription of the U12 spliceosomal machinery. The majority of TP53 mutation-associated transcripts are involved in chromatin remodeling and nucleosome assembly, and are enriched for histone cluster 1 genes. These linker histones are crucial for maintaining higher-order chromatin structure and for regulating gene expression, demonstrating the interplay between genetic and epigenetic states. Lastly, miR-34A is associated with transcriptional regulation of a host of lincRNAs, including LINC-PINT, a p53-induced lincRNA. These results are the first to identify miR-34A as an important node in the transcriptional regulation of numerous noncoding RNAs and point to further study of these pathways.

Taken together, these findings provide strong support for the impact of TP53 mutations on epigenetic dysregulation in human cancer susceptibility and demonstrate that miR-34A may be important in the pathogenesis of TP53-mediated cancer susceptibility. Moreover, miR-34A may be a putative novel therapeutic target and a marker for clinical prognostication. These studies also demonstrate that miR-34A is a central node in numerous p53-dependent and independent networks and provide further insight into the role of this critical tumor-suppressive microRNA. Further work aimed at refining our understanding of miR-34A-mediated pathways may yield additional molecular insight into the role of this microRNA in malignant transformation.

Citation Format: Nardin Samuel, Gavin Wilson, Genevieve Deblois, Badr Id Said, Nicholas W. Fischer, Mathieu Lemire, Youliang Lou, Weili Li, Roumiana Alexandrova, Ana Novokmet, James Tran, Kim E. Nichols, Jonathan L. Finlay, Sanaa Choufani, Marc Remke, Vijay Ramaswamy, Florence M.G. Cavalli, Christine Elser, Lynn Meister, Michael D. Taylor, Uri Tabori, Meredith Irwin, Rosanna Weksberg, Jonathan D. Wasserman, Jean Gariepy, Mathieu Lupien, Daniele Merico, Andrew Paterson, Jordan R. Hansford, Maria Isabel W. Achatz, Thomas J. Hudson, David Malkin. TP53-mediated human cancer susceptibility is defined by epigenetic dysregulation of microRNA-34A [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr NG05. doi:10.1158/1538-7445.AM2017-NG05

Abstract P5-11-02: Impact of pre-operative exercise and mind-body interventions on patient-reported outcomes in women with newly diagnosed breast cancer

Background: Breast cancer diagnosis has a number of adverse psychological effects. The Pre-Operative Health and Body (PreHAB) Study tested the impact of exercise and mind-body interventions upon on mood, quality of life, and patient-reported outcomes in women with newly diagnosed breast cancer.

Methods: Women with newly diagnosed Stage I-III breast cancer were enrolled through Dana-Farber Cancer Institute and Yale University breast cancer clinics prior to surgery. Participants were randomized 1:1 to an aerobic and strength-training exercise intervention, comprised of twice-weekly meetings with an exercise trainer and home based aerobic exercise, or to a self-directed mind-body relaxation intervention, comprised of a book and CD focused on relaxation and visualization. Participants engaged in the interventions between enrollment and surgery. The EORTC QLQ C-30, Hospital Anxiety and Depression Scale, and Perceived Stress Scale were collected at enrollment and prior to surgery.

Results: 49 women were randomized (27 exercise and 22 control). Mean time between enrollment and surgery was 4.2 weeks. At baseline, patients reported moderate levels of anxiety, stress, insomnia, and lack of appetite, as well as diminished emotional and cognitive functioning (Table). Exercise participants significantly increased minutes of weekly exercise vs. mind-body participants (increase of 203 vs. 23 min/wk, p&lt;0.0001). Mind body participants engaged in the intervention on average 69% of days during the intervention period. Pre-post changes demonstrated that participation in the mind-body intervention led to improvements in emotional and cognitive functioning and a reduction in anxiety and stress, and participation in the exercise intervention led to improvements in global quality of life, insomnia, appetite, and stress (Table). Women in the mind-body group experienced a significantly greater improvement in cognitive functioning as compared to women in the exercise group.

Conclusions: Women with newly diagnosed breast cancer reported a number of physical and psychological symptoms in the pre-operative period. Exercise and mind-body interventions demonstrated promising benefits in improving functioning and reducing symptoms. More work is needed to develop pre-operative programs to help reduce the distress imparted by a cancer diagnosis in the critical time between diagnosis and surgery.

Table*

 Exercise Mind Body Between Groups BaselineChangep valueBaselineChangep valuep valueEmotional Functioning68.6 (23.3)4.7 (18.3)0.2966.3 (24.2)10.0 (20.5)0.050.64Cognitive Functioning79.5 (24.6)-3.3 (24.1)0.6273.8 (22.1)11.7 (15.4)0.0020.03QOL74.0 (15.3)9.7 (15.9)0.00569.0 (21.1)7.5 (18.5)0.110.78Insomnia35.9 (32.6)-16.7 (32.6)0.0334.9 (35.7)-8.3 (21.3)0.060.52Lack of Appetite17.9 (27.0)-13.3 (27.2)0.0311.1 (19.2)-5.0 (22.4)0.530.29Anxiety8.3 (3.4)-0.6 (2.9)0.259.2 (2.5)-1.6 (2.3)0.0060.35Stress14.7 (7.2)-2.2 (4.9)0.0618.4 (5.5)-3.1 (6.8)0.060.77

*Results reported as means (SD). Positive scores on functional and QOL measures indicate improvements; negative scores on symptom measures indicate a decrease in symptoms.

Citation Format: Ligibel JA, Giobbie-Hurder A, Dillion D, Shockro L, Campbell N, Rhei E, Troyan S, Dominici L, Golshan M, Chagpar A, Yung R, Freedman R, Tolaney S, Winer E, Frank E, McTiernan A, Irwin M. Impact of pre-operative exercise and mind-body interventions on patient-reported outcomes in women with newly diagnosed breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-11-02.

Abstract S5-05: Impact of pre-operative exercise on breast cancer gene expression

Background: Exercise is linked to a lower risk of developing and dying from breast cancer, but the biological mechanisms through which exercise could impact breast cancer are unclear. In animal models, exercise impacts tumor formation and progression, but there are few data regarding direct effects of exercise on tumor tissue in humans. The Pre-Operative Health and Body (PreHAB) Study was a randomized window of opportunity trial designed to explore the impact of exercise on molecular pathways in women with breast cancer.

Methods: Inactive women with Stage I-III breast cancer were enrolled through Dana-Farber Cancer Institute and Yale University prior to surgery. Participants were randomized 1:1 to an aerobic and strength training exercise intervention or mind body control intervention and participated in the interventions between enrollment and the time of surgery. Tumor tissue was collected at enrollment and surgery; samples were reviewed by a breast pathologist and were macrodissected to include sections of tumor with at least 10% cellularity. Capture RNA-sequencing of the transcriptome coding regions was performed using the Illumina Truseq RNA access platform.

Results: 49 women were randomized (27 exercise and 22 control). At baseline, mean age was 52.6, BMI was 30.2kg/m2 and exercise was 49 min/wk. Mean time between enrollment and surgery was 4.2 weeks. Participants in the exercise arm significantly increased exercise vs. controls (increase of 203 vs. 23 min/wk, p&lt;0.0001). Transcriptomic analysis was performed on the tumors from the pre and post intervention biopsies from 32 patients (16 exercise and 16 control). Quality Control analysis of the RNA-sequencing data showed an average read depth of 25 million reads per sample, mapping ∼79% to exonic regions. Principal Component Analysis revealed no read bias or batch effects and unsupervised clustering showed that pre- and post-operative samples clustered together by patient. Differential gene expression analysis by DEseq2 revealed a limited number of individual genes with significant changes after the intervention. KEGG pathway analysis, however, of 214 KEGG pathways using the bioconductor package GAGE (Generally Applicable Gene-Set Enrichment for Pathway Analysis) demonstrated upregulation of 13 unique pathways between the baseline biopsy and surgical excision in exercise participants and none in mind body participants (q&lt;0.1). The top ranked upregulated pathway was cytokine-cytokine receptor interactions (q=6.93E-05, set size=238 genes). Il6, CCL3 and other cytokines are among the genes upregulated in this pathway. Analysis also demonstrated downregulation of 13 unique pathways (q&lt;0.1) including cell cycle, RNA transport and DNA replication pathways, in exercise participants over the intervention period.

Conclusions: A pre-operative exercise intervention led to alterations in gene expression in tumor tissue in women with breast cancer. Validation in additional data sets and an analysis of which cellular compartments within the tumor are responsible for the changes is needed. These findings demonstrate that exercise may have a direct effect on breast tumor tissue in humans, providing new insights into the biologic mechanisms through which exercise could lower the risk of developing and dying from breast cancer.

Citation Format: Ligibel JA, Irwin M, Dillon D, Barry W, Giobbie-Hurder A, Frank E, Winer EP, McTiernan A, Cornwell M, Pun M, Brown M, Jeselsohn R. Impact of pre-operative exercise on breast cancer gene expression [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr S5-05.

Socioeconomic status and lifestyle behaviours in cancer survivors: smoking and physical activity

PURPOSE

Smoking cessation and increased physical activity (pa) have been linked to better outcomes in cancer survivors. We assessed whether socioeconomic factors influence changes in those behaviours after a cancer diagnosis.

METHODS

As part of a cross-sectional study, a diverse group of cancer survivors at the Princess Margaret Cancer Centre (Toronto, ON), completed a questionnaire about past and current lifestyle behaviours and perceptions about the importance of those behaviours with respect to their health. The influence of socioeconomic indicators on smoking status and physical inactivity at 1 year before and after diagnosis were assessed using multivariable logistic regression with adjustment for clinico-demographic factors.

RESULTS

Of 1222 participants, 1192 completed the smoking component. Of those respondents, 15% smoked before diagnosis, and 43% of those smokers continued to smoke after. The proportion of survivors who continued to smoke increased with lower education level (p = 0.03). Of the 1106 participants answering pa questions, 39% reported being physically inactive before diagnosis, of whom 82% remained inactive afterward. Survivors with a lower education level were most likely to remain inactive after diagnosis (p = 0.003). Lower education level, household income, and occupation were associated with the perception that pa had no effect or could worsen fatigue and quality of life (p ≤ 0.0001).

CONCLUSIONS

In cancer survivors, education level was a major modifier of smoking and pa behaviours. Lower socioeconomic status was associated with incorrect perceptions about pa. Targeting at-risk survivors by education level should be evaluated as a strategy in cancer survivorship programs.

Genome-Wide DNA Methylation Analysis Reveals Epigenetic Dysregulation of MicroRNA-34A in TP53-Associated Cancer Susceptibility

PURPOSE

Although the link between mutant TP53 and human cancer is unequivocal, a significant knowledge gap exists in clinically actionable molecular targets in Li-Fraumeni syndrome (LFS), a highly penetrant cancer predisposition syndrome associated with germline mutations in TP53. This study surveyed the epigenome to identify functionally and clinically relevant novel genes implicated in LFS.

PATIENTS AND METHODS

We performed genome-wide methylation analyses of peripheral blood leukocyte DNA in germline TP53 mutation carriers (n = 72) and individuals with TP53 wild type in whom histologically comparable malignancies developed (n = 111). Targeted bisulfite pyrosequencing was performed on a validation cohort of 30 TP53 mutation carriers and 46 patients with TP53 wild type, and candidate sites were evaluated in primary tumors from patients with LFS across multiple histologic tumor types.

RESULTS

In 183 patients, distinct DNA methylation signatures were associated with deleterious TP53 mutations in peripheral blood leukocytes. TP53-associated DNA methylation marks occurred in genomic regions that harbored p53 binding sites and in genes encoding p53 pathway proteins. Moreover, loss-of-function TP53 mutations were significantly associated with differential methylation at the locus encoding microRNA miR-34A, a key component of the p53 regulatory network (adjusted P < .001), and validated in an independent patient cohort (n = 76, P < .001). Targeted bisulfite pyrosequencing demonstrated that miR-34A was inactivated by hypermethylation across many histologic types of primary tumors from patients with LFS. Moreover, miR-34A tumor hypermethylation was associated with decreased overall survival in a cohort of 29 patients with choroid plexus carcinomas, a characteristic LFS tumor (P < .05).

CONCLUSION

Epigenetic dysregulation of miR-34A may comprise an important path in TP53-associated cancer predisposition and represents a therapeutically actionable target with potential clinical relevance.

Abstract P3-08-01: Randomized controlled trial of weight loss vs. usual care on telomere length in women with breast cancer: The lifestyle, exercise and nutrition (LEAN) study

PURPOSE: Some studies suggest that telomere shortening due to repeated cell divisions may be associated with increased breast cancer risk and mortality. Obesity is also associated with increased breast cancer risk and mortality. Few studies have examined telomere length as a potential mechanism/biomarker mediating the obesity-breast cancer association. One study published of a diet, physical activity and support intervention in prostate cancer patients found a positive association between lifestyle changes and relative lengthening of telomeres, and another study of weight loss in healthy postmenopausal women observed no effect of weight loss on leukocyte telomere length. The purpose of our study was to examine the effect of a 6-month diet- and exercise-induced weight loss intervention vs. usual care on telomere length in 100 breast cancer survivors.

METHODS: 100 breast cancer survivors with BMI≥25 kg/m2 were randomly assigned to a weight loss counseling intervention with either telephone or in-person counseling (n = 67) or usual care group (n=33). Weight loss counseling included eleven 30-minute counseling sessions over 6 months, focusing on reducing caloric intake, increasing physical activity and behavioral therapy. Body composition (height, weight, and DEXA scans), physical activity and diet were measured at baseline and 6-months. Fasting blood samples were also collected at baseline and 6 months. Relative telomere length (T/S: telomere length/single copy of gene albumin) was measured by quantitative-polymerase chain reaction (qPCR) done on buffy coat extracted genomic DNA. Mean baseline to 6-month changes were compared between groups (intent-to-treat) using generalized estimating equations and Pearson correlation coefficients.

RESULTS: Baseline characteristics were similar for women randomized to each group. Women were 59±7 years, with BMI 33.1±6.6 kg/m2 and were 2.9±2.1 years from diagnosis; 91% were non-Hispanic white, and 51% were diagnosed with Stage I breast cancer. Average 6-month weight loss was 6.2% and 2.0% for weight loss and usual care groups, respectively (p=0.0004). At baseline, higher % body fat was associated with shorter T/S (r = -0.31, P=0.012). After 6 months, women randomized to weight loss experienced a 4% T/S lengthening compared to a 5% T/S shortening in the usual care group (P=0.10) (Table 1).

Effect of weight loss vs. usual care on leukocyte telomere lengthLEAN VariableUsual Care  Weight Loss Group  TelomereNMeanSDNMeanSDBaseline330.850.26630.750.216 Month Change26-0.040.21540.030.18  (-5%)  (+4%)p=.10SD=Standard Deviation

CONCLUSION: Our results indicate that higher % body fat is associated with shorter leukocyte telomere length, and weight loss was associated with an increase in leukocyte telomere length, suggesting that telomere length may be a mechanism mediating the relationship between obesity and breast cancer risk and mortality.

Citation Format: Sanft T, Lu L, Harrigan M, Cartmel B, Zhou Y, Chagpar A, Pusztai L, Irwin M. Randomized controlled trial of weight loss vs. usual care on telomere length in women with breast cancer: The lifestyle, exercise and nutrition (LEAN) study. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-08-01.

Bridging the Distance in the Caribbean: Telemedicine as a means to build capacity for care in paediatric cancer and blood disorders

Over the past 50 years, survival for children in high-income countries has increased from 30% to over 80%, compared to 10-30% in low and middle income countries (LMIC). Given this gap in survival, established paediatric cancer treatment centres, such as The Hospital for Sick Children (SickKids) are well positioned to share clinical expertise. Through the SickKids Centre for Global Child Health, the SickKids-Caribbean Initiative (SCI) was launched in March 2013 to improve the outcomes and quality of life for children with cancer and blood disorders in the Caribbean. The six participating Caribbean countries are among those defined by the United Nations as Small Island Developing States, due to their small size, remote location and limited accessibility. Telemedicine presents an opportunity to increase their accessibility to health care services and has been used by SCI to facilitate two series of interprofessional rounds. Case Consultation Review Rounds are a forum for learning about diagnostic work-up, management challenges and treatment recommendations for these diseases. To date, 54 cases have been reviewed by SickKids staff, of which 35 have been presented in monthly rounds. Patient Care Education Rounds provide nurses and other staff with the knowledge base needed to safely care for children and adolescents receiving treatment. Five of these rounds have taken place to date, with over 200 attendees. Utilized by SCI for both clinical and non-clinical meetings, telemedicine has enhanced opportunities for collaboration within the Caribbean region. By building capacity and nurturing expert knowledge through education, SCI hopes to contribute to closing the gap in childhood survival between high and low-resource settings.

Metastatic neuroblastoma confined to distant lymph nodes (stage 4N) to predict outcome in patients with stage 4 disease: A study from the International Neuroblastoma (NB) Risk Group (INRG) Database

10015

Background: Patients with metastatic NB typically have a poor prognosis; however case series have suggested that those with 4N disease may have improved outcomes. Methods: Retrospective analysis of data from INRG database for patients diagnosed 1990–2002. 4N patients (INSS stage 4 disease confined to distant lymph nodes) were compared to the balance of stage 4 patients (‘non-4N’), excluding those with missing metastatic site data. 5-yr estimates of overall (OS) and event-free survival (EFS) were calculated ± standard error (Kaplan-Meier method). Patient characteristics were compared by Mann-Whitney or Fisher’s exact/Chi-square tests. Results: 2,250 INSS stage 4 patients with complete data were identified, of whom 146 (6%) had 4N disease. For 4N patients, EFS and OS (5-yr: 77% ± 4%, 85% ± 3%), were significantly better than EFS and OS (5-yr: 35% ± 1%, 42% ± 1%) for non-4N stage 4 patients (p<0.0001). 4N patients were more likely to be younger (median age at diagnosis 1.2 yr vs 2.5 yr for non-4N; p<0.0001) and have tumors with favourable International Neuroblastoma Pathologic Classification (INPC) (63% vs 26%, p<0.0001), differentiating grade (21% vs 8%, p=0.006), lower MKI (p=0.0011) and non-MYCN amplified tumors (89% vs 69%, p<0.0001). Within subgroups defined by age at diagnosis and MYCN status, 4N pattern of disease remained significantly associated with improved outcomes. For patients aged ≥547 days at diagnosis and MYCN non-amplified, 5-yr EFS for 4N patients (n=42) was 63% ± 8% vs 27% ± 2% for non-4N (n=785); OS 74% ± 7% vs 38% ± 2% (both p<0.0001). Within this subgroup, favourable INPC and differentiating grade remained more frequent in the 4N vs non-4N patients (45% vs 10%, p<0.0001; 45% vs 8%, p=0.0017, respectively). Conclusions: 4N represents a subgroup of metastatic patients with better outcome than other INSS stage 4 patients. These findings indicate that the biology and response to treatment of 4N tumors differs from other stage 4 tumors, and different therapies should be considered for this cohort. Future exploration of biological factors determining pattern of metastatic spread and response to therapy is warranted.

Astronomical algorithms for automated analysis of tissue protein expression in breast cancer

BACKGROUND

High-throughput evaluation of tissue biomarkers in oncology has been greatly accelerated by the widespread use of tissue microarrays (TMAs) and immunohistochemistry. Although TMAs have the potential to facilitate protein expression profiling on a scale to rival experiments of tumour transcriptomes, the bottleneck and imprecision of manually scoring TMAs has impeded progress.

METHODS

We report image analysis algorithms adapted from astronomy for the precise automated analysis of IHC in all subcellular compartments. The power of this technique is demonstrated using over 2000 breast tumours and comparing quantitative automated scores against manual assessment by pathologists.

RESULTS

All continuous automated scores showed good correlation with their corresponding ordinal manual scores. For oestrogen receptor (ER), the correlation was 0.82, P<0.0001, for BCL2 0.72, P<0.0001 and for HER2 0.62, P<0.0001. Automated scores showed excellent concordance with manual scores for the unsupervised assignment of cases to 'positive' or 'negative' categories with agreement rates of up to 96%.

CONCLUSION

The adaptation of astronomical algorithms coupled with their application to large annotated study cohorts, constitutes a powerful tool for the realisation of the enormous potential of digital pathology.

Abstract C35: The development of metastatic mouse models of neuroblastoma to bone and brain to identify the molecular mechanisms governing metastasis

Metastasis is a key reason for the lack of success in treating children with neuroblastoma (NB). Over 50% of patients present with metastatic lesions in the bone, brain, liver and lymph nodes, with a high fatality rate for patients that relapse with those metastases. A better understanding of the molecular processes defining the complexity and multi-step nature of NB dissemination is required for the development of effective treatments. To date, there is no NB model that quantitatively and reproducibly metastasizes to bone and brain. Thus, we developed novel metastatic mouse models of neuroblastoma to bone and brain through in vivo selection to enhance metastatic capability. SK-N-AS, derived from a bone marrow metastasis, and IMR-32, a MYCN-amplified line derived from an abdominal mass, were tagged for in vivo monitoring using a triple reporter (TR) encoding TK, GFP and firefly luciferase, which allows for nuclear imaging, FACs analysis, and whole body bioluminescence. Reporter expression was confirmed by double sorting for GFP and testing for luciferase activity. Cells were introduced into the blood stream of NOD/SCID mice through intra-cardiac injection, and monitored bi-weekly using bioluminescence. SK-N-ASTR cells metastasized to the adrenal gland (87%, 13/15 animals) and bone (mandible, hindlimbs, 67%, 10/15 animals), whereas IMR-32TR cells metastasized to bone (100%, 10/10 animals) and brain (40%, 4/10 animals). Metastatic lesions were confirmed by ex-vivo bioluminescence, 3D bioluminescence, MRI or micro-CT. Cells from specific metastatic sites of individual mice were isolated, expanded in culture, GFP sorted and injected into a second cohort of mice. Several of the SK-N-ASTR re-injected cell lines derived from bone exhibited enhanced metastasis after one round of in vivo selection, with 100% metastasis to bone and the adrenal gland (a common location of primary NB tumours) and up to 60% metastasis to brain, as confirmed by MRI. Subsequently, these animals had a decreased overall survival rate of approximately 43 days relative to the parental cell line, of 69 days. The metastatic sub-populations do not proliferate at higher rates than the parental cell line, as assessed by BrdU labeling. Thus, the enhanced metastasis observed in vivo is not due to a faster growth rate, but rather selection of metastasis promoting functions. This is supported by the finding that the metastatic SK-N-ASTR sub-populations also exhibited enhanced migration and invasion toward serum, as assessed using boyden chambers, compared to the parental line. These sub-populations are being characterized to identify the molecular mechanisms governing metastasis. Metastasis to brain and bone is an often fatal event in children with newly diagnosed and recurrent NB. We have developed the first reproducible and efficient NB metastatic mouse model to identify novel genes and signalling proteins regulating metastasis, and to identify drug candidates that suppress metastatic growth.

Citation Format: Kelly E. Fathers, Samar Mouaaz, Constanza Rioseco, Anna Mourskaia, Ronald Blasberg, Meredith Irwin, Peter Siegel, David Kaplan. The development of metastatic mouse models of neuroblastoma to bone and brain to identify the molecular mechanisms governing metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr C35.

Neuroblastoma: the impact of biology and cooperation leading to personalized treatments

Neuroblastoma is the most common extra-cranial solid tumor in children. It is a heterogeneous disease, consisting of neural crest-derived tumors with remarkably different clinical behaviors. It can present in a wide variety of ways, including lesions which have the potential to spontaneously regress, or as an extremely aggressive form of metastatic cancer which is resistant to all forms of modern therapy. They can arise anywhere along the sympathetic nervous system. The median age of presentation is approximately 18 months of age. Urinary catecholamines (HVA and VMA) are extremely sensitive and specific tumor markers and are used in diagnosis, treatment response assessment and post-treatment surveillance. The largest national treatment groups from North America, Europe and Japan have formed the International Neuroblastoma Risk Group Task Force (INRG) to identify prognostic factors, to understand the mechanisms of tumorigenesis in this rare disease and to develop multi-modality therapies to improve outcomes and decrease treatment-related toxicities. This international cooperation has resulted in a significant leap in our understanding of the molecular pathogenesis of neuroblastoma. Lower staged disease can be cured if the lesion is resectable. Treatment of unresectable disease (loco-regional and metastatic) is stratified depending on clinical features (age at presentation, staging investigations) and specific tumor biological markers that include histopathological analyses, chromosomal abnormalities and the quantification of expression of an oncogene (MYCN). Modern treatment of high-risk neuroblastoma is the paradigm for the evolution of therapy in pediatric oncology. Outcomes have improved substantially with multi-modality therapy, including chemotherapy, surgery, radiation therapy, myeloablative therapy with stem cell transplant, immunotherapy and differentiation therapy; these comprise the standard of care worldwide. In addition, newer targeted therapies are being tested in phase I/II trials. If successful these agents will be incorporated into mainstream treatment programs.

Tissue expanders: early experience of a novel treatment option for perineal herniation

PURPOSE

Acquired perineal hernias through the reconstructed pelvic floor can complicate radical pelvic operations including abdominoperineal resection of rectum. Operative intervention is indicated for symptomatic hernias. There is a lack of consensus as to the best operative technique. Here we present a novel method for repairing perineal herniation using saline-filled tissue expanders.

METHODS

Perineal hernia repair may be affected either via an abdominal or via a perineal approach. After adhesiolysis to remove small bowel from the pelvis, a Natrelle™ 150SH tissue expander (Allergan Inc., California, USA) or Siltex™ Round Becker (Mentor Medical Systems, Holland) of appropriate size is inserted in the pelvis and the button placed in a subcutaneous pocket in the perineal skin. The tissue expander is then filled with saline until it fills the true anatomical pelvis without bladder compression. The volume may be increased or decreased postoperatively by accessing the subcutaneous button.

RESULTS

We have performed this procedure in three patients with some success, all of whom have experienced symptomatic relief. The tissue expander may subsequently be removed without recurrence of symptoms, due to the fibrous capsule which forms. One patient required re-operation to elevate a herniating tissue expander. The tissue expander was removed earlier than anticipated to avoid deep pelvic infection in another.

CONCLUSION

Our early experience suggests that using saline-filled tissue expanders to fill dead space in the pelvis after radical surgery may prove to be a valuable approach to perineal herniation, particularly if adjuvant radiotherapy is planned.

Hydronephrosis in children with abdominal and pelvic neoplasms: outcome and survival analysis of a single center pediatric oncology series

PURPOSE

We ascertained the incidence and outcome of hydronephrosis related to abdominal or pelvic neoplasms and survival in pediatric patients.

MATERIALS AND METHODS

We retrospectively reviewed our institutional oncology database between January 1995 and November 2009. We reviewed the charts of all children with intra-abdominal (nonrenal) and pelvic neoplasms.

RESULTS

Of the 366 patients whose charts were reviewed 66 (18%) had hydronephrosis at some point during treatment, including 12 with hydronephrosis that was not caused by the neoplasm and 1 who was lost to followup, leaving 53 with malignant obstruction. Of the remaining patients hydronephrosis resolved in 34 (64%) with treatment for the primary neoplasm alone while in 19 (36%) hydronephrosis persisted after primary oncological treatment. Univariate analysis revealed that patients with persistent hydronephrosis (p = 0.025), those with urological intervention (p = 0.05) and those with high stage disease (p <0.001) had statistically significantly worse overall survival. On Cox multivariate analysis only disease stage remained statistically significant (p = 0.004).

CONCLUSIONS

Analysis of this group revealed that pediatric nonrenal abdominal and pelvic tumors are associated with hydronephrosis in about 20% of cases. Approximately 60% of these cases resolved with treatment for the primary tumor alone while 13% required specific urological intervention for urinary tract involvement or compression. Patients with pediatric malignant ureteral obstruction had a 20% 5-year mortality rate. The main predictive factor was primary disease stage.

A review of web-based weight loss interventions in adults

Unprecedented obesity rates are changing the burden of disease worldwide and obesity-related health complications are increasing healthcare costs. In response, researchers, clinicians and public health practitioners are seeking new and effective tools such as the Internet to effect weight loss. This review highlights peer-reviewed literature on randomized controlled trials that examine Internet-delivered weight loss and maintenance programmes. The scope of this review is broader than previous reviews, including more males and non-Caucasian participants. The reviewed studies show intervention results ranging from no weight loss to an average loss of 7.6 kg. It is difficult to draw a definitive conclusion on the potential impact of Internet-based weight loss as study methods are highly variable between papers, low adherence was recorded and not all studies include a control group. As the demand for low-cost, efficacious interventions that yield statistically significant and/or clinically relevant results grows, more rigorous, population-specific research is needed to determine if Internet-delivered interventions may slow or reverse with weight gain and obesity and the associated health consequences.

CERTAIN EFFECTS OF SALTS ON THE PENETRATION OF BRILLIANT CRESYL BLUE INTO NITELLA

The effect of various substances on living cells may be advantageously studied by exposing them to such substances and observing their subsequent behavior in solutions of a basic dye, brilliant cresyl blue. The rate of penetration of the basic dye, brilliant cresyl blue, is decreased when cells are exposed to salts with monovalent cations before they are placed in the dye solution (made up with borate buffer mixture). This inhibiting effect is assumed to be due to the effect of the salts on the protoplasm. This effect is not readily reversible when cells are transferred to distilled water, but it is removed by salts with bivalent or trivalent cations. In some cases it disappears in dye made up with phosphate buffer mixture, or with borate buffer mixture at the pH value in which the borax predominates, and in the case of NaCl it disappears in dye containing NaCl. No inhibiting effect is seen when cells are exposed to NaCl solution containing MgCl₂ before they are placed in the dye solution. The rate of penetration of dye is not decreased when cells are previously exposed to salts with bivalent and trivalent cations. The rate is slightly increased when cells are placed in the dye solution containing a salt with monovalent cation and probably with bivalent or trivalent cations. In the case of the bivalent and trivalent salts the increase is so slight that it may be negligible.

ON THE NATURE OF THE DYE PENETRATING THE VACUOLE OF VALONIA FROM SOLUTIONS OF METHYLENE BLUE

When uninjured cells of Valonia are placed in methylene blue dissolved in sea water it is found, after 1 to 3 hours, that at pH 5.5 practically no dye penetrates, while at pH 9.5 more enters the vacuole. As the cells become injured more dye enters at pH 5.5, as well as at pH 9.5. No dye in reduced form is found in the sap of uninjured cells exposed from 1 to 3 hours to methylene blue in sea water at both pH values. When uninjured cells are placed in azure B solution, the rate of penetration of dye into the vacuole is found to increase with the rise in the pH value of the external dye solution. The partition coefficient of the dye between chloroform and sea water is higher at pH 9.5 than at pH 5.5 with both methylene blue and azure B. The color of the dye in chloroform absorbed from methylene blue or from azure B in sea water at pH 5.5 is blue, while it is reddish purple when absorbed from methylene blue and azure B at pH 9.5. Dry salt of methylene blue and azure B dissolved in chloroform appears blue. It is shown that chiefly azure B in form of free base is absorbed by chloroform from methylene blue or azure B dissolved in sea water at pH 9.5, but possibly a mixture of methylene blue and azure B in form of salt is absorbed from methylene blue at pH 5.5, and azure B in form of salt is absorbed from azure B in sea water at pH 5.5. Spectrophotometric analysis of the dye shows the following facts. 1. The dye which is absorbed by the cell wall from methylene blue solution is found to be chiefly methylene blue. 2. The dye which has penetrated from methylene blue solution into the vacuole of uninjured cells is found to be azure B or trimethyl thionine, a small amount of which may be present in a solution of methylene blue especially at a high pH value. 3. The dye which has penetrated from methylene blue solution into the vacuole of injured cells is either methylene blue or a mixture of methylene blue and azure B. 4. The dye which is absorbed by chloroform from methylene blue dissolved in sea water is also found to be azure B, when the pH value of the sea water is at 9.5, but it consists of azure B and to a less extent of methylene blue when the pH value is at 5.5. 5. Methylene blue employed for these experiments, when dissolved in sea water, in sap of Valonia, or in artificial sap, gives absorption maxima characteristic of methylene blue. Azure B found in the sap collected from the vacuole cannot be due to the transformation of methylene blue into this dye after methylene blue has penetrated into the vacuole from the external solution because no such transformation detectable by this method is found to take place within 3 hours after dissolving methylene blue in the sap of Valonia. These experiments indicate that the penetration of dye into the vacuole from methylene blue solution represents a diffusion of azure B in the form of free base. This result agrees with the theory that a basic dye penetrates the vacuole of living cells chiefly in the form of free base and only very slightly in the form of salt. But as soon as the cells are injured the methylene blue (in form of salt) enters the vacuole. It is suggested that these experiments do not show that methylene blue does not enter the protoplasm, but they point out the danger of basing any theoretical conclusion as to permeability on oxidation-reduction potential of living cells from experiments made or the penetration of dye from methylene blue solution into the vacuole, without determining the nature of the dye inside and outside the cell.

THE PENETRATION OF DYES AS INFLUENCED BY HYDROGEN ION CONCENTRATION

When cells of Nitella are placed in buffer solutions at pH 9, there is a very slow and gradual increase in the pH of the sap from pH 5.6 to 6.4 (when death of the cells takes place). If the living cells are placed in 0.002 per cent dye solutions of brilliant cresyl blue at different pH values (from pH 6.6 to pH 9), it is found that the rate of penetration of the dye, and the final equilibrium attained, increases with increase in pH value, which can be attributed to an increase in the active protein (or other amphoteric electrolyte) in the cell which can combine with the dye.

SPECTROPHOTOMETRIC STUDIES OF PENETRATION : V. RESEMBLANCES BETWEEN THE LIVING CELL AND AN ARTIFICIAL SYSTEM IN ABSORBING METHYLENE BLUE AND TRIMETHYL THIONINE

The rate of diffusion through the non-aqueous layer of the protoplasm depends largely on the partition coefficients mentioned above. Since these cannot be determined we have employed an artificial system in which chloroform is used in place of the non-aqueous layer of the protoplasm. The partition coefficients may be roughly determined by shaking up the aqueous solutions with chloroform and analyzing with the spectrophotometer (which is necessary with methylene blue because we are dealing with mixtures). This will show what dyes may be expected to pass through the protoplasm into the vacuole in case it behaves like the artificial system. From these results we may conclude that the artificial system and the living cell act almost alike toward methylene blue and azure B, which supports the notion of non-aqueous layers in the protoplasm. There is a close resemblance between Valonia and the artificial system in their behavior toward these dyes at pH 9.5. In the case of Nitella, on the other hand, with methylene blue solution at pH 9.2 the sap in the artificial system takes up relatively more azure B (absorption maximum at 650 mµ) than the vacuole of the living cell (655 mµ). But both take up azure B much more rapidly than methylene blue. A comparison cannot be made between the behavior of the artificial system and that of the living cell at pH 5.5 since in the latter case there arises a question of injury to cells before enough dye is collected in the sap for analysis.

THE BEHAVIOR OF CHLORIDES IN THE CELL SAP OF NITELLA

1. A method is given for determining the chloride content in a drop (less than 0.03 cc.) of the cell sap of Nitella. 2. Chlorides accumulate in the sap to the extent of 0.128 M; this accumulation can be followed during the growth of the cell. The chloride content does not increase when the cell is placed for 2 days in solutions (at pH 6.2) containing chlorides up to 0.128 M. 3. The exosmosis of chlorides from injured cells can be followed quantitatively. When one end of the cell is cut off a wave of injury progresses toward the other end; this is accompanied by a progressive exosmosis of chlorides.

MECHANISM OF THE ACCUMULATION OF DYE IN NITELLA ON THE BASIS OF THE ENTRANCE OF THE DYE AS UNDISSOCIATED MOLECULES

The rate of penetration of brilliant cresyl blue into the living cells of Nitella indicates that the dye enters only in the form of the undissociated molecule. At equilibrium the total concentration of the dye in the sap is proportional to the concentration of the free base in the outside solution.

STUDIES ON PENETRATION OF DYES WITH GLASS ELECTRODE : V. WHY DOES AZURE B PENETRATE MORE READILY THAN METHYLENE BLUE OR CRYSTAL VIOLET?

Glass electrode measurements of the pH value of the sap of cells of Nitella show that azure B in the form of free base penetrates the vacuoles and raises the pH value of the sap to about the same degree as the free base of the dye added to the sap in vitro, but the dye salt dissolved in the sap does not alter the pH value of the sap. It is concluded that the dye penetrates the vacuoles chiefly in the form of free base and not as salt. The dye from methylene blue solution containing azure B free base as impurity penetrates and accumulates in the vacuole. This dye must be azure B in the form of free base, since it raises the pH value of the sap to about the same extent as the free base of azure B dissolved in the sap in vitro. The dye absorbed by the chloroform from methylene blue solution behaves like the dye penetrating the vacuole. These results confirm those of spectrophotometric analysis previously published. Crystal violet exists only in one form between pH 5 and pH 9.2, and does not alter the pH value of the sap at the concentrations used. It does not penetrate readily unless cells are injured. A theory of "multiple partition coefficients" is described which explains the mechanism of the behavior of living cells to these dyes. When the protoplasm is squeezed into the sap, the pH value of the mixture is higher than that of the pure sap. The behavior of such a mixture to the dye is very much like that of the sap except that with azure B and methylene blue the rise in the pH value of such a mixture is not so pronounced as with sap when the dye penetrates into the vacuoles. Spectrophotometric measurements show that the dye which penetrates from methylene blue solution has a primary absorption maximum at 653 to 655 mµ (i.e., is a mixture of azure B and methylene blue, with preponderance of azure B) whether we take the sap alone or the sap plus protoplasm. These results confirm those previously obtained with spectrophotometric measurements.

ACCUMULATION OF BRILLIANT CRESYL BLUE IN THE SAP OF LIVING CELLS OF NITELLA IN THE PRESENCE OF NH(3)

When the living cells of Nitella are placed in a solution of brilliant cresyl blue containing NH(4)Cl, the rate of accumulation of the dye in the sap is found to be lower than when the cells are placed in a solution of dye containing no NH(4)Cl and this may occur without any increase in the pH value of the cell sap. This decrease is found to be primarily due to the presence of NH(3) in the sap and seems not to exist where NH(3) is present only in the external solution at the concentration used.

THE EFFECT OF ACETATE BUFFER MIXTURES, ACETIC ACID, AND SODIUM ACETATE, ON THE PROTOPLASM, AS INFLUENCING THE RATE OF PENETRATION OF CRESYL BLUE INTO THE VACUOLE OF NITELLA

When living cells of Nitella are exposed to a solution of sodium acetate and are then placed in a solution of brilliant cresyl blue made up with a borate buffer mixture at pH 7.85, a decrease in the rate of penetration of dye is found, without any change in the pH value of the sap. It is assumed that this inhibiting effect is caused by the action of sodium on the protoplasm. This effect is not manifest if the dye solution is made up with phosphate buffer mixture at pH 7.85. It is assumed that this is due to the presence of a greater concentration of base cations in the phosphate buffer mixture. In the case of cells previously exposed to solutions of acetic acid the rate of penetration of dye decreases with the lowering of the pH value of the sap. This inhibiting effect is assumed to be due chiefly to the action of acetic acid on the protoplasm, provided the pH value of the external acetic acid is not so low as to involve an inhibiting effect on the protoplasm by hydrogen ions as well. It is assumed that the acetic acid either has a specific effect on the protoplasm or enters as undissociated molecules and by subsequent dissociation lowers the pH value of the protoplasm. With acetate buffer mixture the inhibiting effect is due to the action of sodium and acetic acid on the protoplasm. The inhibiting effect of acetic acid and acetate buffer mixture is manifested whether the dye solution is made up with borate or phosphate buffer mixture at pH 7.85. It is assumed that acetic acid in the vacuole serves as a reservoir so that during the experiment the inhibiting effect still persists.

SPECTROPHOTOMETRIC STUDIES OF PENETRATION : IV. PENETRATION OF TRIMETHYL THIONIN INTO NITELLA AND VALONIA FROM METHYLENE BLUE

Spectrophotometric measurements show that it is chiefly the trimethyl thionin that is present in the sap extracted from the vacuoles of uninjured cells of Nitella or Valonia which have been placed in methylene blue solution at a little above pH 9. Whether these measurements were made immediately or several hours later the same results were obtained. Methylene blue is detected in the sap (1) when the cells are injured or (2) when the contamination of the sap from the stained cell wall occurs at the time of extraction. The sap is found to be incapable of demethylating methylene blue dissolved in it even on standing for several hours. It is somewhat uncertain as to whether the trimethyl thionin penetrated as such from the external methylene blue solution which generally contains this dye as impurity (in too small concentration for detection by spectrophotometer but detectable by extraction with chloroform), or whether it has formed from methylene blue in the protoplasm. The evidences described in the text tend to favor the former explanation. Theory is discussed on basis of more rapid penetration of trimethyl thionin (in form of free base) than of methylene blue, or of trimethyl thionin in form of salt.