Habitat escalated adaptive therapy (HEAT): a phase 2 trial utilizing radiomic habitat-directed and genomic-adjusted radiation dose (GARD) optimization for high-grade soft tissue sarcoma

BACKGROUND

Soft tissue sarcomas (STS), have significant inter- and intra-tumoral heterogeneity, with poor response to standard neoadjuvant radiotherapy (RT). Achieving a favorable pathologic response (FPR ≥ 95%) from RT is associated with improved patient outcome. Genomic adjusted radiation dose (GARD), a radiation-specific metric that quantifies the expected RT treatment effect as a function of tumor dose and genomics, proposed that STS is significantly underdosed. STS have significant radiomic heterogeneity, where radiomic habitats can delineate regions of intra-tumoral hypoxia and radioresistance. We designed a novel clinical trial, Habitat Escalated Adaptive Therapy (HEAT), utilizing radiomic habitats to identify areas of radioresistance within the tumor and targeting them with GARD-optimized doses, to improve FPR in high-grade STS.

METHODS

Phase 2 non-randomized single-arm clinical trial includes non-metastatic, resectable high-grade STS patients. Pre-treatment multiparametric MRIs (mpMRI) delineate three distinct intra-tumoral habitats based on apparent diffusion coefficient (ADC) and dynamic contrast enhanced (DCE) sequences. GARD estimates that simultaneous integrated boost (SIB) doses of 70 and 60 Gy in 25 fractions to the highest and intermediate radioresistant habitats, while the remaining volume receives standard 50 Gy, would lead to a > 3 fold FPR increase to 24%. Pre-treatment CT guided biopsies of each habitat along with clip placement will be performed for pathologic evaluation, future genomic studies, and response assessment. An mpMRI taken between weeks two and three of treatment will be used for biological plan adaptation to account for tumor response, in addition to an mpMRI after the completion of radiotherapy in addition to pathologic response, toxicity, radiomic response, disease control, and survival will be evaluated as secondary endpoints. Furthermore, liquid biopsy will be performed with mpMRI for future ancillary studies.

DISCUSSION

This is the first clinical trial to test a novel genomic-based RT dose optimization (GARD) and to utilize radiomic habitats to identify and target radioresistance regions, as a strategy to improve the outcome of RT-treated STS patients. Its success could usher in a new phase in radiation oncology, integrating genomic and radiomic insights into clinical practice and trial designs, and may reveal new radiomic and genomic biomarkers, refining personalized treatment strategies for STS.

TRIAL REGISTRATION

NCT05301283.

TRIAL STATUS

The trial started recruitment on March 17, 2022.

Respiratory viral infection promotes the awakening and outgrowth of dormant metastatic breast cancer cells in lungs

Breast cancer is the second most common cancer globally. Most deaths from breast cancer are due to metastatic disease which often follows long periods of clinical dormancy1. Understanding the mechanisms that disrupt the quiescence of dormant disseminated cancer cells (DCC) is crucial for addressing metastatic progression. Infection with respiratory viruses (e.g. influenza or SARS-CoV-2) is common and triggers an inflammatory response locally and systemically2,3. Here we show that influenza virus infection leads to loss of the pro-dormancy mesenchymal phenotype in breast DCC in the lung, causing DCC proliferation within days of infection, and a greater than 100-fold expansion of carcinoma cells into metastatic lesions within two weeks. Such DCC phenotypic change and expansion is interleukin-6 (IL-6)-dependent. We further show that CD4 T cells are required for the maintenance of pulmonary metastatic burden post-influenza virus infection, in part through attenuation of CD8 cell responses in the lungs. Single-cell RNA-seq analyses reveal DCC-dependent impairment of T-cell activation in the lungs of infected mice. SARS-CoV-2 infected mice also showed increased breast DCC expansion in lungs post-infection. Expanding our findings to human observational data, we observed that cancer survivors contracting a SARS-CoV-2 infection have substantially increased risks of lung metastatic progression and cancer-related death compared to cancer survivors who did not. These discoveries underscore the significant impact of respiratory viral infections on the resurgence of metastatic cancer, offering novel insights into the interconnection between infectious diseases and cancer metastasis.

Support Through Remote Observation and Nutrition Guidance (STRONG), a digital health intervention to reduce malnutrition among pancreatic cancer patients: A study protocol for a pilot randomized controlled trial

Background

Malnutrition is a common and distressing condition among pancreatic cancer patients. Fewer than a quarter of pancreatic cancer patients receive medical nutrition therapy (MNT), important for improving nutritional status, weight maintenance, quality of life and survival. System, provider, and patient level barriers limit access to MNT. We propose to examine the feasibility of a 12-week multi-level, digital health intervention designed to expand MNT access among pancreatic cancer patients.

Methods

Individuals with advanced pancreatic cancer starting chemotherapy (N = 80) will be 1:1 randomized to the intervention or usual care. The Support Through Remote Observation and Nutrition Guidance (STRONG) intervention includes system-level (e.g., routine malnutrition and screening), provider-level (e.g., dietitian training and web-based dashboard), and patient-level strategies (e.g., individualized nutrition plan, self-monitoring of dietary intake via Fitbit, ongoing goal monitoring and feedback). Individuals receiving usual care will be referred to dietitians based on their oncologists' discretion. Study assessments will be completed at baseline, 4-, 8-, 12-, and 16-weeks.

Results

Primary outcomes will be feasibility (e.g., recruitment, retention, assessment completion) and acceptability. We will collect additional implementation outcomes, such as intervention adherence, perceived usability, and feedback on intervention quality via an exit interview. We will collect preliminary data on outcomes that may be associated with the intervention including malnutrition, quality of life, treatment outcomes, and survival.

Conclusion

This study will advance our knowledge on the feasibility of a digital health intervention to reduce malnutrition among individuals with advanced pancreatic cancer. Trial registration: NCT05675059, registered on December 9, 2022.

Stereotactic body radiotherapy plus rucosopasem in locally advanced or borderline resectable pancreatic cancer: GRECO-2 phase II study design

Ablative doses of stereotactic body radiotherapy (SBRT) may improve pancreatic cancer outcomes but may carry greater potential for gastrointestinal toxicity. Rucosopasem, an investigational selective dismutase mimetic that converts superoxide to hydrogen peroxide, can potentially increase tumor control of SBRT without compromising safety. GRECO-2 is a phase II, multicenter, randomized, double-blind, placebo-controlled trial of rucosopasem in combination with SBRT in locally advanced or borderline resectable pancreatic cancer. Patients will be randomized to rucosopasem 100 mg or placebo via intravenous infusion over 15 min, before each SBRT fraction (5 × 10 Gy). The primary end point is overall survival. Secondary end points include progression-free survival, locoregional control, time to metastasis, surgical resection rate, best overall response, in-field local response and acute and long-term toxicity.

Pancreatic Cyst Size Measurement on Magnetic Resonance Imaging Compared to Pathology

BACKGROUND

While multiple cyst features are evaluated for stratifying pancreatic intraductal papillary mucinous neoplasms (IPMN), cyst size is an important factor that can influence treatment strategies. When magnetic resonance imaging (MRI) is used to evaluate IPMNs, no universally accepted sequence provides optimal size measurements. T2-weighted coronal/axial have been suggested as primary measurement sequences; however, it remains unknown how well these and maximum all-sequence diameter measurements correlate with pathology size. This study aims to compare agreement and bias between IPMN long-axis measurements on seven commonly obtained MRI sequences with pathologic size measurements.

METHODS

This retrospective cohort included surgically resected IPMN cases with preoperative MRI exams. Long-axis diameter tumor measurements and the presence of worrisome features and/orhigh-risk stigmata were noted on all seven MRI sequences. MRI size and pathology agreement and MRI inter-observer agreement involved concordance correlation coefficient (CCC) and intraclass correlation coefficient (ICC), respectively. The presence of worrisome features and high-risk stigmata were compared to the tumor grade using kappa analysis. The Bland-Altman analysis assessed the systematic bias between MRI-size and pathology.

RESULTS

In 52 patients (age 68 ± 13 years, 22 males), MRI sequences produced mean long-axis tumor measurements from 2.45-2.65 cm. The maximum MRI lesion size had a strong agreement with pathology (CCC = 0.82 (95% CI: 0.71-0.89)). The maximum IPMN size was typically observed on the axial T1 arterial post-contrast and MRCP coronal series and overestimated size versus pathology with bias +0.34 cm. The radiologist interobserver agreement reached ICCs 0.74 to 0.91 on the MRI sequences.

CONCLUSION

The maximum MRI IPMN size strongly correlated with but tended to overestimate the length compared to the pathology, potentially related to formalin tissue shrinkage during tissue processing.

Stereotactic body radiotherapy with or without selective dismutase mimetic in pancreatic adenocarcinoma: an adaptive, randomised, double-blind, placebo-controlled, phase 1b/2 trial

BACKGROUND

Stereotactic body radiotherapy (SBRT) has the potential to ablate localised pancreatic ductal adenocarcinoma. Selective dismutase mimetics sensitise tumours while reducing normal tissue toxicity. This trial was designed to establish the efficacy and toxicity afforded by the selective dismutase mimetic avasopasem manganese when combined with ablative SBRT for localised pancreatic ductal adenocarcinoma.

METHODS

In this adaptive, randomised, double-blind, placebo-controlled, phase 1b/2 trial, patients aged 18 years or older with borderline resectable or locally advanced pancreatic cancer who had received at least 3 months of chemotherapy and had an Eastern Cooperative Oncology Group performance status of 0-2 were enrolled at six academic sites in the USA. Eligible patients were randomly assigned (1:1), with block randomisation (block sizes of 6-12) with a maximum of 24 patients per group, to receive daily avasopasem (90 mg) or placebo intravenously directly before (ie, within 180 min) SBRT (50, 55, or 60 Gy in five fractions, adaptively assigned in real time by Bayesian estimates of 90-day safety and efficacy). Patients and physicians were masked to treatment group allocation, but not to SBRT dose. The primary objective was to find the optimal dose of SBRT with avasopasem or placebo as determined by the late onset EffTox method. All analyses were done on an intention-to-treat basis. This study is registered with ClinicalTrials.gov, NCT03340974, and is complete.

FINDINGS

Between Jan 25, 2018, and April 29, 2020, 47 patients were screened, of whom 42 were enrolled (median age was 71 years [IQR 63-75], 23 [55%] were male, 19 [45%] were female, 37 [88%] were White, three [7%] were Black, and one [2%] each were unknown or other races) and randomly assigned to avasopasem (n=24) or placebo (n=18); the placebo group was terminated early after failing to meet prespecified efficacy parameters. At data cutoff (June 28, 2021), the avasopasem group satisfied boundaries for both efficacy and toxicity. Late onset EffTox efficacy response was observed in 16 (89%) of 18 patients at 50 Gy and six (100%) of six patients at 55 Gy in the avasopasem group, and was observed in three (50%) of six patients at 50 Gy and nine (75%) of 12 patients at 55 Gy in the placebo group, and the Bayesian model recommended 50 Gy or 55 Gy in five fractions with avasopasem for further study. Serious adverse events of any cause were reported in three (17%) of 18 patients in the placebo group and six (25%) of 24 in the avasopasem group. In the placebo group, grade 3 adverse events within 90 days of SBRT were abdominal pain, acute cholangitis, pyrexia, increased blood lactic acid, and increased lipase (one [6%] each); no grade 4 events occurred. In the avasopasem group, grade 3-4 adverse events within 90 days of SBRT were acute kidney injury, increased blood alkaline phosphatase, haematoma, colitis, gastric obstruction, lung infection, abdominal abscess, post-surgical atrial fibrillation, and pneumonia leading to respiratory failure (one [4%] each).There were no treatment-related deaths but one late death in the avasopasem group due to sepsis in the setting of duodenal obstruction after off-study treatment was reported as potentially related to SBRT.

INTERPRETATION

SBRT that uses 50 or 55 Gy in five fractions can be considered for patients with localised pancreatic ductal adenocarcinoma. The addition of avasopasem might further enhance disease outcomes. A larger phase 2 trial (GRECO-2, NCT04698915) is underway to validate these results.

FUNDING

Galera Therapeutics.

The optimized rectal cancer MRI protocol: choosing the right sequences, sequence parameters, and preparatory strategies

Pelvic MRI plays a critical role in rectal cancer staging and treatment response assessment. Despite a consensus regarding the essential protocol components of a rectal cancer MRI, substantial differences in image quality persist across institutions and vendor software/hardware platforms. In this review, we present image optimization strategies for rectal cancer MRI examinations, including but not limited to preparation strategies, high-resolution T2-weighted imaging, and diffusion-weighted imaging. Our specific recommendations are supported by case studies from multiple institutions. Finally, we describe an ongoing initiative by the Society of Abdominal Radiology's Disease-Focused Panel (DFP) on Rectal and Anal Cancer to create standardized rectal cancer MRI protocols across scanner platforms.

Greco-2: A randomized, phase 2 study of stereotactic body radiation therapy (SBRT) in combination with rucosopasem (GC4711) in the treatment of locally advanced or borderline resectable nonmetastatic pancreatic cancer

TPS766

Background: While treatment of pancreatic cancer has advanced, survival rates remain low. Stereotactic body radiotherapy (SBRT; high dose per fraction radiation) may exhibit improved clinical outcomes in locally advanced pancreatic cancer but carries potential gastrointestinal toxicity risks. Rucosopasem (GC4711) is one of a class of investigational selective dismutase mimetics that rapidly and specifically converts superoxide to hydrogen peroxide. Studies have shown that normal cells tolerate hydrogen peroxide fluxes better than cancer cells. As radiation response modifiers, dismutase mimetics have the potential to increase tumor control of SBRT without compromising radiation safety. In a pilot phase 1/2 trial in patients with pancreatic cancer, avasopasem, a dismutase mimetic related to rucosopasem, nearly doubled median overall survival in patients receiving SBRT vs placebo plus SBRT. Improvements versus placebo were also observed in local tumor control, time to metastases, and progression-free survival. Altogether, these data support the hypothesis that rucosopasem may improve survival and the benefit-risk ratio of SBRT by improving efficacy without increasing gastrointestinal toxicity. Methods: GRECO-2 is a phase 2, multicenter, randomized, double-blind, placebo-controlled study (NCT04698915) to determine the effect of adding rucosopasem to SBRT on overall survival in patients with borderline resectable or locally advanced, unresectable nonmetastatic pancreatic cancer following initial chemotherapy with a FOLFIRINOX-based regimen or a gemcitabine doublet. Approximately 160 patients will be randomized (approximately 35 sites) to receive rucosopasem 100 mg or placebo via IV infusion over 15 minutes, prior to each SBRT fraction (5 x 10 Gy). Patients judged to be resectable will undergo surgical exploration within 8 weeks after SBRT. The primary endpoint is overall survival. Secondary endpoints include progression-free survival, locoregional control, time to metastasis, surgical resection rate, RO resection rate, best overall response, in-field local response, and safety (acute and late toxicities). Exploratory endpoints include PRO-CTCAE and CA19-9 normalization. This trial (NCT04698915) is now enrolling. Clinical trial information: NCT04698915 .

OR07-2 Endocrine Response And Resistance Is Driven By Novel Transcriptional Co-Regulator Activity In Invasive Lobular Carcinoma Of The Breast

Invasive lobular carcinoma of the breast (ILC) affects ∼40,000 US women annually and is a top ten most diagnosed cancer in women. ∼95% of ILC express estrogen receptor alpha (ER), but ILC is associated with poor long-term outcomes and anti-estrogen resistance, suggesting ER function is distinct in ILC cells. We reported that MDC1 (mediator of DNA damage checkpoint 1) is an ILC-specific ER co-regulator required for ER-driven proliferation, and that MDC1 knockdown dysregulates the ER transcriptome in ILC. Mechanisms of MDC1 co-regulator activity are unknown, but must be defined to understand endocrine response and resistance in ILC.

To understand MDC1 co-regulator functions, we profiled ER/MDC1 genomic binding (ie. "cistrome") using CUT&RUN in ER+ ILC cell line MDA MB 134VI (MM134). We identified ∼2500 binding sites each for ER and MDC1, but only ∼8% of sites were bound by both factors. However, using BETA to integrate cistrome and transcriptome data predicted that both ER and MDC1 activate estrogen-regulated genes with over half of direct ER target genes also direct MDC1 targets (p=9.8×10-375). Among shared ER: MDC1 direct target genes (n=760), 58% had MDC1 binding in the promoter region with ER bound at nearby enhancers, while only 15% were linked to shared ER: MDC1 binding sites, suggesting MDC1 primarily facilitates promoter access for ER-bound enhancers. Further, MDC1 knockdown reduced ER binding at enhancer sites at ER: MDC1 target genes, implicating MDC1 in regulating chromatin access.

Importantly, MDC1 does not have known enzymatic activity to directly regulate chromatin structure. We profiled MDC1-interacting proteins in ILC cells by RIME (Rapid immunoprecipitation mass spectrometry of endogenous proteins), and determined whether knockdown of putative ER: MDC1 partners disrupted ER function. This identified the SWI/SNF complex protein BRG1 (SMARCA4) as a critical ER: MDC1 partner. BRG1 was required for ILC cell growth, and BRG1 knockdown specifically suppressed ER regulation of MDC1-dependent ER target genes.

Taken together, our data suggest that in ILC cells, MDC1 facilitates ER access to and activity at target gene promoters. The BRG1 SWI/SNF complex is a putative ER: MDC1 partner and mediator of MDC1 co-regulator functions. Ongoing research is focused on understanding how MDC1 regulates ILC-specific ER activity by licensing access to ILC-specific target genes, and the role of the SWI/SNF complex in mediating genomic ER: MDC1 activity.

Presentation: Saturday, June 11, 2022 11:45 a.m. - 12:00 p.m.

Placenta Accreta Spectrum: A 2-year Retrospective Observational Study

Aims To assess the management and outcomes of Placenta Accreta Spectrum disorders and highlight the important management recommendations from international guidelines. Methods A retrospective audit of women diagnosed with Placenta Accreta Spectrum disorder from January 2018 to December 2019. Results Nine cases (0.16%) of placenta accreta from 5695 births were identified. All women received caesarean section under general anaesthesia. Caesarean hysterectomy occurred in seven cases (78%). Mean (±SD) age of women was (34.4 ± 3.9 years) and mean parity score was (3.2 ± 1.2). Mean gestational age at birth was 35.1 ± 0.8 weeks. Bilateral iliac artery balloon occlusion occurred in eight (89%) cases. Median estimated blood loss [range] was 1700 mL [1000-7000] with only 11% of patients (1/9) experiencing more than 3L of blood loss. Intraoperative red blood cell transfusion occurred in six cases (67%). Median number of units of red cell transfusion [range] was four units [0-10]. Mean hospital length of stay was (6.7 ± 1.1 days) and there were no maternal deaths. Multidisciplinary team involvement of senior anaesthetists and obstetricians was noted in all cases. Discussion Placenta accreta spectrum is increasing in incidence in obstetric practice and is associated with significant maternal morbidity and mortality. Implementing national guidelines can improve patient outcomes.

GRECO-2: A randomized, phase 2 study of stereotactic body radiation therapy (SBRT) in combination with rucosopasem (GC4711) in the treatment of locally advanced or borderline resectable nonmetastatic pancreatic cancer

TPS4184

Background: While treatment of pancreatic cancer has advanced, survival rates remain low. Stereotactic body radiotherapy (SBRT; high dose per fraction radiation) may exhibit improved clinical outcomes in locally advanced pancreatic cancer but carries potential gastrointestinal toxicity risks (Zhong 2017). Rucosopasem (GC4711) is one of a class of investigational selective dismutase mimetics that rapidly and specifically converts superoxide to hydrogen peroxide (Riley 2006). Studies have shown that normal cells tolerate hydrogen peroxide fluxes better than cancer cells (Doskey 2016). As radiation response modifiers, dismutase mimetics have the potential to increase tumor control of SBRT without compromising radiation safety (El-Mahdy 2020, Sishc 2021). In a pilot phase 1/2 trial in patients with pancreatic cancer, avasopasem, a dismutase mimetic related to rucosopasem, nearly doubled median overall survival in patients receiving SBRT vs placebo plus SBRT. Improvements versus placebo were also observed in local tumor control, time to metastases, and progression-free survival. Altogether, these data support the hypothesis that rucosopasem may improve survival and the benefit-risk ratio of SBRT by improving efficacy without increasing gastrointestinal toxicity. Materials/Methods: GRECO-2 is a phase 2, multicenter, randomized, double-blind, placebo-controlled study (NCT04698915) to determine the effect of adding rucosopasem to SBRT on overall survival in patients with borderline resectable or locally advanced, unresectable nonmetastatic pancreatic cancer following initial chemotherapy with a FOLFIRINOX-based regimen or a gemcitabine doublet. Approximately 160 patients will be randomized (approximately 35 sites) to receive rucosopasem 100 mg or placebo via IV infusion over 15 minutes, prior to each SBRT fraction (5 x 10 Gy). Patients judged to be resectable will undergo surgical exploration within 8 weeks after SBRT. The primary endpoint is overall survival. Secondary endpoints include progression-free survival, locoregional control, time to metastasis, surgical resection rate, RO resection rate, best overall response, in-field local response, and safety (acute and late toxicities). Exploratory endpoints include PRO-CTCAE and CA19-9 normalization. This trial is now enrolling. Clinical trial information: NCT04698915.

COVID-19, Telemedicine and Emergency Department Referrals: Patient Presentations and Follow-up Times to a Community Mental Health Team

Introduction

The COVID-19 pandemic caused changes to how healthcare services are utilised and delivered.

Objectives

We examine the impact of COVID-19 on the pattern of emergency patient presentations referred on to the community mental health team and the impact of utilising telemedicine on time to follow-up.

Methods

We retrospectively reviewed all clinical records of patients currently attending our service. We identified presentations to the emergency department (N=119) who were subsequently referred on for mental health follow-up.

Results

Patients being referred to our team from emergency departments were significantly younger during, mean age 33.1 years (SD=12.3) compared to before the pandemic, mean age 40.0 years (SD=14.5), p=0.006 and a higher proportion were new patients during, 55.8%, compared to pre-pandemic period 33.3%, p=0.015. There was also a higher proportion of patients presenting with suicidal ideation and lower proportions of affective, psychosis and suicidal/self-injurious acts during the pandemic period compared to before, p=0.006. The ratio of female to male patients on the other hand were similar during both periods, p=0.853. There appeared to be no difference in median time to follow-up pre and during the pandemic (6.0 vs 5.5 days, p=0.995). Further analysis also found no significant impact on time to follow-up upon implementing telemedicine consultations, with median days to initial follow-up of 6 days pre-pandemic, 4.5 days during pandemic + prior to telemedicine and 6.5 days during pandemic + telemedicine, p=0.602.

Conclusions

This study provides preliminary data on the impact of COVID-19 on mental health emergency presentations and utilization of telemedicine on time to follow-up by CMHTs.

Disclosure

No significant relationships.

GRECO-2: A randomized, phase 2 study of stereotactic body radiation therapy (SBRT) in combination with GC4711 in the treatment of unresectable or borderline resectable nonmetastatic pancreatic cancer (PC)

TPS4175

Background: While systemic treatment of PC has improved, rates of surgical resection - considered optimum treatment - remain low. Patients with un-resectable or borderline PC still have poor outcomes, with both toxicity and disease progression during induction chemotherapy limiting the number eligible for surgery. SBRT practice to enhance margin negative resection or to provide local control, if inoperable after neoadjuvant therapy, has shifted to higher dose delivery (Mellon 2015, Colbert 2018), but timing and appropriate patient selection are under constant debate. SBRT delivery over 50Gy exhibits superior cell killing compared to conventionally fractionated RT but carries potential GI toxicity risk (Zhong 2017). GC4711 is a selective superoxide dismutase mimetic that converts superoxide to hydrogen peroxide. As radiation response modifiers, dismutase mimetics have the potential to increase tumor control without compromising radiation safety (Sishc, AACR 2019). GC4711 consistently augmented tumor control by SBRT in PC experimental xenograft mouse models. In a pilot phase 1/2 trial (GC4419-101), subjects with locally advanced PC were randomized to receive SBRT plus either the selective dismutase mimetic GC4419 or placebo. This pilot trial has demonstrated acceptable safety with SBRT (5 × 10-11Gy), as well as apparent improvements in survival, surgical resection, locoregional control, and time to distant metastases. Altogether, these data support the hypothesis that GC4711 may improve tumor outcomes and the benefit-risk ratio of 5-fraction SBRT delivering 50Gy by improving efficacy without increasing GI-toxicity. Methods: GRECO-2 is a phase 2, multicenter, randomized, double-blind, placebo-controlled study to determine the effect on overall survival of adding GC4711 to SBRT following 4 months of chemotherapy in subjects with un-resectable or borderline non-metastatic PC. Approximately 160 subjects will be enrolled at over 20 sites to receive GC4711 100 mg or placebo IV given as IV infusion over 15 min, prior to each of 5 SBRT fractions of 10Gy). Subjects judged operable will be explored within 8 weeks after SBRT. All subjects will complete 2 additional months of adjuvant chemotherapy. Primary end point is overall survival and secondary endpoints address resection rates, local and distant disease progression, and safety, while exploratory studies include ctDNA, tumor exome/transcriptome sequencing, and immune profiling, patient-reported symptoms (PRO-CTCAE), CA19.9 normalization, and radiomics. Colbert L, Rebueno N, Moningi S et al Advances in Radiation Oncology (2018) 3, 693-700 Mellon EA, Hoffe SE, Springett GM, et al Acta Oncologica, 2015;54:7 Zhong J, Patel K, Switchenko J, et al. Cancer. 2017 Sep 15;123(18):3486-3493. Sishc BJ, Saha D, Story MD. AACR PADC 2019 C52. Clinical trial information: NCT04698915.

Endoscopic and MRI response evaluation following neoadjuvant treatment for rectal cancer: a pictorial review with matched MRI, endoscopic, and pathologic examples

A nonoperative management strategy, or Watch-and-Wait, following neoadjuvant therapies of locally advanced rectal adenocarcinoma is increasingly considered for select patients. Yet, standardized tumor response assessment to best select and surveil suitable patients remains an unmet clinical challenge. Endoscopic and MRI currently provide the most reliable tumor response estimations. However, resources illustrating variable tumor responses to neoadjuvant therapies remain limited. This pictorial review aims to provide detailed and annotated examples of common endoscopic and MRI findings of rectal cancer treatment response, while also emphasizing their respective diagnostic shortcomings and consequently, the necessity for a multidisciplinary approach to optimally manage these patients.

Abstract 908: BRAF inhibition and nanoparticle-delivered cytokine therapy for melanoma: A novel rational combined approach

Although the advent of BRAF inhibitors plus MEK inhibitors has revolutionized BRAF-mutant melanoma therapy, most patients relapse within 16 months due to the persistence of minimal residual disease (MRD), a key obstacle in cancer therapy. In our inducible genetically engineered mouse model (iBIP), doxycycline withdrawal results in BRAFV600E extinction causing tumors to shrink, but not completely disappear, achieving a status of MRD. Time-course microarray analysis revealed a set of immune hallmarks with acute and strong initial activation after BRAFV600E extinction, then a decrease through to MRD, suggesting that the MRD might be immune suppressive/evasive.

Systems biology analysis pinpointed the family of interferon inducible chemokines CXCL9/10/11 as central players in the orchestration of the process: CXCL9/10/11 are strongly induced within 8 hours of BRAFV600E extinction, but dissipate just prior to MRD, paralleling the more general immune signature. Data obtained in human samples and in other immunocompetent mouse models also show both a strong CXCL9/10/11 induction after BRAF inhibition and an immune evasive/suppressive microenvironment after eventual tumor relapse. Our preliminary data indicates resident macrophages as the main population responsible for CXCL9/10/11 production.. These data led us to hypothesize that sustaining CXCL9/10/11 expression might support superior tumor immune infiltration and activation to neutralize or eradicate the MRD.

In a pilot study, we have observed significant tumor rejection in vivo with combined BRAF extinction plus intratumoral recombinant CXCL9 (rCXCL9) therapy in immunocompetent mice, which suggests that CXCL9 can therapeutically convert immunologically “cold” MRD back to “hot”. In order to improve the pharmacokinetics of cytokine therapy, we are currently developing a nanoparticle-based delivery that extends stability and half-life of rCXLC9 in vitro, with in vivo experiments as the next step. In this work, we utilized a confluence of in silico and in vivo data to guide the rational identification of a molecularly-driven cancer treatment based on immune drivers with predicted molecular synergy.

Citation Format: Gabriele Romano, Roger Liang, Paradiso Francesca, John Miller, Francesca Taraballi, James Costello, Lawrence Kwong. BRAF inhibition and nanoparticle-delivered cytokine therapy for melanoma: A novel rational combined approach [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 908.

Value of anterosuperior rotator cuff and labral tears at MRI for predicting long head of biceps tearing at arthroscopy

AIM

To determine whether magnetic resonance imaging (MRI) signs of subscapularis (SBT), supraspinatus (SST), or superior labral tearing predict long head of biceps (LHB) tendon tearing at arthroscopy.

MATERIALS AND METHODS

Subjects with MRI studies followed by arthroscopy were collected. Radiologists graded rotator cuff (RC) tendons and the superior labrum using three grade classifications and blinded to arthroscopy. Correlation between imaging variables and surgical outcome was expressed in terms of odds ratios and determined using a stepwise logistic regression model.

RESULTS

Selection criteria identified 89 participants. Statistically significant increase in odds of finding a partial LHB tendon tear at arthroscopy were noted for both MRI readers with any SBT tear (OR=4.1-5.6, p<0.0001 to 0.002), full-thickness SST (OR=8-20.4, p=0.002 to 0.006), and combined SST-SBT tears (OR=5.1-7.6, p<0.0001 to 0.002) and relative to grade 0 MRI scores for those categories. Statistically significant increase in the odds of finding any LHB tendon tear at arthroscopy were noted for both MRI readers with any SBT tear (OR=9.6 to 14.6, p<0.0001), full-thickness SST (OR=9.0 to 52.0, p<0.0001 to 0.0004) and combined SST-SBT tears (OR=8.2 to 15.1, p<0.0001) at MRI and relative to grade 0 MRI scores for these categories. No significant predictive effect was found for the labral categories.

CONCLUSION

LHB tendons should be closely scrutinised if anterosuperior rotator cuff tears, and SBT tears in particular, are found on MRI.

Abstract 5001: Identification of a Six2/Sox2/Nanog stem cell axis that promotes breast cancer metastatic colonization

Although significant progress has been made in understanding the molecular mechanisms that lead to metastatic breast cancer, it remains the overwhelming cause of death for patients. Current studies primarily focus on the prevention of early stages of metastasis, such as migration and invasion. But at the time of diagnosis tumor cells have likely left the primary tumor, suggesting that inhibition of the early stages of metastasis may not be the most effective means of inhibiting metastatic burden. Instead, the identification and targeting of molecules required for establishment and survival of cells at secondary sites is imperative for advancing therapies. We are examining the role of the developmental transcription factor Six2 in promoting metastatic burden. Six2 is a member of the Six family of transcription factors and is responsible for the maintenance of stem/progenitor cells during nephrogenesis. Using knockdown (KD) and overexpression (OE) models in murine mammary cells, we demonstrated that Six2 promotes specifically late-stage metastasis (growth at the secondary site). RNA-Seq analysis on control and Six2 OE cells showed a dramatic enrichment in stem cell transcriptional programs downstream of Six2 in mammary/breast cancer cells. Flow cytometry analyses and tumorsphere assays demonstrate that Six2 OE leads to an increase, whereas Six2 KD leads to a decrease, in the mammary stem cell population and tumorsphere formation, respectively. Using an immune competent mouse model, in vivo orthotopic limiting-dilution experiments reveal that Six2 regulates tumor initiation. In addition, we show that Six2 regulates late-stage metastasis of human breast cancer cells in vivo, as measured by metastatic burden after tail vein injection. Thus, our data demonstrate that Six2 similarly promotes stem phenotypes in breast cancer cells as it does during kidney development, and suggest that this attribute may be critical for its ability to promote metastatic outgrowth. To determine the molecular mechanism by which Six2 mediates stem phenotypes and metastasis in breast cancer, we interrogated our RNA-seq data, which suggested that Six2 may control master regulators of stemness. We demonstrate that both Sox2 and Nanog are regulated by Six2. In human breast cancer gene expression datasets, Six2 significantly positively correlates with both Sox2 and Nanog, and combined OE of Six2 with either Sox2 or Nanog results in poor prognosis. Preliminary data suggest that loss of Sox2 downstream of Six2 inhibits metastatic outgrowth, and that Sox2 is upstream of Nanog in the pathway. Together, our data demonstrate that Six2 regulates cancer stem phenotypes to promote metastatic outgrowth, uncovering a novel Six2/Sox2/Nanog axis that is critical for metastatic colonization.

Citation Format: Michael U. Oliphant, Ahwan Pandey, Katherine Johnson, Rani Powers, Matthew Galbraith, James Costello, Heide L. Ford. Identification of a Six2/Sox2/Nanog stem cell axis that promotes breast cancer metastatic colonization [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5001.

Abstract B05: BRAF inhibition and cytokine therapy for melanoma: A novel rational combined approach

Although the advent of BRAF inhibitors (BRAFi) plus MEK inhibitors (MEKi) has revolutionized melanoma therapy, most patients relapse within 16 months due to the persistence of minimal residual disease (MRD), a key obstacle in cancer therapy. Many efforts focus on combining this regimen with specific immune therapies, but clinical trials have so far uncovered no synergy and/or unacceptable toxicity. The critical knowledge gap that must be addressed in order to optimize such a combination is to identify the key drivers of the immune response to BRAFi as nodes for therapeutic synergy. To achieve this aim, we used our recently published model of melanoma (iBIP) to produce microarray data over a time course from early in BRAF extinction through to MRD and then tumor relapse. In the iBIP genetically engineered mouse model, doxycycline (dox) administration controls BRAFV600E expression. Interestingly, dox withdrawal resulting in BRAFV600E extinction is able to shrink the tumors, but not to make them completely disappear. As a result, in this model we have a minimal residual disease (MRD) of 5-20% of the original tumor volume. The microarray analysis confirmed that expected hallmarks of BRAFV600E extinction were present, resulting in BRAF and ERK pathway signature and a proliferation pathway signature decrease over time. Next, we detected a set of immune hallmarks with the following trend: acute and strong initial activation after BRAFV600E extinction, then a decrease through to MRD. These genes included markers of both CD4+ and CD8+ T cells, as well as NK cells and macrophages. As a result, we hypothesized that a strong immune infiltration, after an initial rapid induction in response to BRAFi, subsequently decreased and returned to baseline. This suggests that the MRD is immune suppressive or immune evasive.

To elucidate drivers of the immune signals, we first conducted a standard pathway analysis and identified cytokines as among the most-enriched immune genesets. We then performed a network analysis using a modification of our previously-described TRAP algorithm, and we identified CXCL9 (known to be involved in T cell mobilization) as the top candidate cytokine. Notably, CXCL9 is strongly induced within 8 hours of BRAFV600E extinction, but dissipates just prior to MRD, paralleling the more general immune signature. Even after iBIP tumors spontaneously relapse, CXCL9 continues to be low. Gene expression data obtained from human samples of BRAFi-responder patients confirm our mouse data showing CXCL9 higher expression in responding patients vs nonresponding. We have obtained promising preliminary results from a pilot experiment combining BRAF extinction with CXCL9 therapy, suggesting that CXCL9 can convert immunologically “cold” MRD back to “hot,” making them susceptible to immune rejection. As a result, in this work we present an approach that utilizes a confluence of in silico and in vivo data that guide the rational identification of a molecularly driven cancer treatment based on immune drivers with predicted molecular synergy.

Citation Format: Gabriele Romano, Roger Liang, Mingguang Liu, John Miller, James Costello, Lawrence Kwong. BRAF inhibition and cytokine therapy for melanoma: A novel rational combined approach [abstract]. In: Proceedings of the AACR Special Conference: Advances in Modeling Cancer in Mice: Technology, Biology, and Beyond; 2017 Sep 24-27; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(10 Suppl):Abstract nr B05.

Use of crowdsourced research to develop a prognostic model for first-line metastatic castrate resistant prostate cancer (mCRPC)

180

Background: Project Data Sphere, LLC (PDS) and Sage Bionetworks/DREAM have completed the “Prostate Cancer DREAM Challenge” (Challenge), a crowdsourced competition, using historical prostate cancer clinical trial data from PDS. The Challenge aimed to improve prognostic models for overall survival (OS) and to explore predictive models for treatment toxicity in mCRPC patients. Methods: Control arms of 4 randomized phase III trials (total 2,070 patients) were used as training and validation data sets for the Challenge: ASCENT2, MAINSAIL, VENICE and ENTHUSE33. All subjects were first line mCRPC patients receiving docetaxel treatment. Curated baseline clinical covariates (demographics, comorbidity, prior treatment, laboratory, lesion and vital signs) were modeled along with raw clinical data tables. The primary purpose of the Challenge was to develop a prognostic model for OS (SubChallenge 1). The models were scored using concordance index and integrated area under receiver operator curve (iAUC) from 6-30 months. The published mCRPC OS model of Halabi, et al., JCO, 2014, was used as the benchmark. Results: The Challenge attracted over 160 active participants who formed 50 teams that submitted final models for SubChallenge 1. Median iAUC was 0.76 (0.67-0.78) with a maximum score of 0.792. Over half (n = 35) of these models exceeded the published benchmark (0.743 iAUC). Teams explored new methodologies such as model-based imputation and machine learning techniques to develop the best performing models. Many leveraged raw clinical data sets to create their own covariates and expanded beyond existing prognostic models. Conclusions: The Challenge externally validated Halabi’s first line prognostic model. New prognostic models were proposed and validated with significant improvements over the benchmark. Further analyses are needed to examine the winning models for new prognostic factors and to validate them using additional trial data from PDS. The Challenge drove interest from cross-disciplinary teams of global experts to explore and enhance their technical abilities using real clinical data whilst serving as a vehicle to accelerate medical innovation.

COXEN prediction of antineoplastic drug sensitivity in bladder cancer patients

365

Background: COXEN (Co-eXpression ExtrapolatioN) uses molecular profiles as a “rosetta stone” for translating drug sensitivities of one set of cancers into predictions for another completely independent set of cell lines or human tumors. The ability of COXEN to predict drug effectiveness in pts using tumor samples from in vitro assays is unique. Methods: We tested the predictive value of COXEN for standard chemotherapies in a cohort of bladder cancer pts. Total RNA was extracted from formalin fixed paraffin embedded (FFPE) tissue and converted to cDNA, amplified with Ovation FFPE WTA, and hybridized to a GeneChip Human Genome U133 Plus 2.0 array. Using gene expression data from 278 independent bladder tumors, COXEN scores were generated using bioinformatics models originally built using the NCI-60 cell line panel and a model building algorithm (MiPP). Gene expression data was processed to score 76 FDA approved antineoplastic drugs. Results: A total of 24 samples were tested (15 tumors with 1 sample and 9 tumors with 2 biological replicas (2 samples from the same tumor)) from 15 pts who received chemotherapy (median age 64 (41-74); 73% male; with muscle invasive bladder cancer (MIBC) (12/15, 80%) or metastatic bladder cancer (mBC) (3/15, 20%)). Response to therapy was confirmed by pathologic response in MIBC pts and radiologic response in mBC pts. Chemotherapies evaluated included: methotrexate/vinblastine/doxorubicin/cisplatin; gemcitabine/cisplatin; gemcitabine/carboplatin; and cisplatin/etoposide. COXEN accurately predicted antineoplastic drug sensitivity in 11/15 (73%) pts (75% MIBC and 67% mBC), of which 7/11 pts had 2 biological samples. However, only 3/7 (43%) biological replicas confirmed COXEN prediction. COXEN accurately predicted drug sensitivity in 9/10 (90%) pts with response and 2/5 (40%) pts with resistance to therapy. Conclusions: COXEN did well in predicting antineoplastic drug response for the majority of bladder cancer pts in this cohort. However, predictions from 2 samples within the same tumor were not always consistent, likely due to the expected tumor heterogeneity found in bladder cancer tumors. A prospective clinical trial in patients with mBC using COXEN to select next best therapy is in development.

MRI of diffuse liver disease: characteristics of acute and chronic diseases

Diffuse liver disease, including chronic liver disease, affects tens of millions of people worldwide, and there is a growing need for diagnostic evaluation as treatments become more readily available, particularly for viral liver diseases. Magnetic resonance imaging (MRI) provides unique capabilities for noninvasive characterization of the liver tissue that rival or surpass the diagnostic utility of liver biopsies. There has been incremental improvement in the use of standardized MRI sequences, acquired before and after administration of a contrast agent, for the evaluation of diffuse liver disease and the study of the liver parenchyma and blood supply. More recent developments have led to methods for quantifying important liver metabolites, including lipids and iron, and liver fibrosis, the hallmark of chronic liver disease. Here, we review the MRI techniques and diagnostic features associated with acute and chronic liver disease.

MRI of hepatocellular carcinoma: an update of current practices

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, and liver transplantation is the optimal treatment for selected patients with HCC and chronic liver disease (CLD). Accurate selection of patients for transplantation is essential to maximize patient outcomes and ensure optimized allocation of donor organs. Magnetic resonance imaging (MRI) is a powerful tool for the detection, characterization, and staging of HCC. In patients with CLD, the MRI findings of an arterial-enhancing mass with subsequent washout and enhancing capsule on delayed interstitial phase images are diagnostic for HCC. Major organizations with oversight for organ donor distribution, such as The Organ Procurement and Transplantation Network (OPTN), accept an imaging diagnosis of HCC, no longer requiring tissue biopsy. In patients that are awaiting transplantation, or are not candidates for liver transplantation, localized therapies such as transarterial chemoembolization and radiofrequency ablation may be offered. MRI can be used to monitor treatment response. The purpose of this review article is to describe the role of imaging methods in the diagnosis, staging, and follow-up of HCC, with particular emphasis on established and evolving MRI techniques employing nonspecific gadolinium chelates, hepatobiliary contrast agents, and diffusion weighted imaging. We also briefly review the recently developed Liver Imaging Reporting and Data System (LI-RADS) formulating a standardized terminology and reporting structure for evaluation of lesions detected in patients with CLD.

MRI of diffuse liver disease: the common and uncommon etiologies

Diffuse liver disease, including all causes of chronic liver disease, affects tens of millions of people worldwide. There is a growing need for diagnostic evaluation as treatments become more readily available, particularly for viral liver disease. Magnetic resonance imaging (MRI) provides unique capabilities for noninvasive characterization of liver tissue that rival or surpass the diagnostic utility of liver biopsies. There has been incremental improvement in the use of standardized MRI sequences, acquired before and after administration of contrast for the evaluation of diffuse liver disease, and this includes study of the liver parenchyma and blood supply. More recent developments have led to methods for quantifying important liver metabolites, including fat and iron, and liver fibrosis, which is the hallmark for chronic liver disease. In this study, we review the MRI techniques and diagnostic features associated with common and uncommon etiologies of diffuse liver diseases, including processes that lead to abnormal perfusion (e.g. Budd-Chiari syndrome, congestive hepatomegaly), deposition diseases (e.g. fatty liver, hemochromatosis, Wilson's disease), and abnormalities that are related to inflammation and fibrosis (e.g. primary sclerosing cholangitis, sarcoidosis).

Chronicles of informal caregiving in cancer: using 'The Cancer Family Caregiving Experience' model as an explanatory framework

BACKGROUND

Cancer caregiving has emerged as a dominant focus of research in recent years. A striking feature of this vast amount of literature is that it is static, examining certain points of the cancer trajectory, mostly the diagnosis and palliative care. Only The Cancer Caregiving Experience Model conceptualised the caregiving experience and explored the conceptual implications of cancer family caregiving research.

AIM

The data from this paper aim to empirically support the Cancer Caregiving Experience model, by exploring the cancer caregiving experience longitudinally.

METHODS

Semi-structured interviews with 53 caregivers were carried out at patient's diagnosis (T1), 3 months (T2), 6 months (T3) and 12 months (T4) post diagnosis.

RESULTS

Analysis of 139 interviews generated four themes that reflected a complex and dynamic process. The themes that mapped those of the model were "Primary stressors", "Secondary stressors", "Appraisal", "Cognitive-Behavioural responses" and "Health and Well Being".

CONCLUSIONS

The study adds empirical support to The Cancer Caregiving Experience Model and confirms that different primary and secondary stressors influence how the caregivers perceive the caregiving demands, the coping mechanisms they employ and their health and well being during the cancer trajectory. Access to support services should be offered to all the caregivers from as early as the diagnosis period and take into account their specific needs.