Initial Tumor Progression Research Articles

Abstract 1091: Distinct mechanisms of orthotopic tumor control by alphavbeta3and HER2 CAR Ts support development of a bispecific CAR T cell therapy for pediatric rhabdomyosarcoma

Abstract Goal: Evaluate αvβ3 and HER2 as antigens for a bispecific chimeric antigen receptor T (CAR T) cell therapy in pediatric rhabdomyosarcoma. Background: Current treatments are ineffective against relapsed/refractory or metastatic rhabdomyosarcoma (RMS). Antigen loss or modulation on tumor cells commonly leads to tumor escape across diverse cancer types after CAR T therapy targeting different antigens. We hypothesize that simultaneously targeting two RMS antigens with a bispecific CAR T will reduce the likelihood of tumor escape. The integrin alphavbeta3 (αvβ3) plays a role in cancer progression, metastasis and neovascularization in several malignancies. HER2 also contributes to cancer progression and metastasis. Methods: Control of intramuscular RMS tumors by αvβ3 or HER2 CAR Ts was assessed in NSG mice, with non-specific CD19 CAR Ts as controls. Tumor burden was assessed weekly by bioluminescence imaging. Persistence and phenotype of CAR Ts were evaluated by flow cytometry. CAR T cell infiltration, tumor antigen expression and residual disease were determined by immunohistochemistry. Results: Six of six pediatric patient-derived RMS cell lines express αvβ3 and/or HER2. αvβ3 and HER2 CAR Ts kill RMS cells in vitro at low effector-to-target ratios. αvβ3 and HER2 CAR Ts independently control—and nearly eliminate—orthotopic RMS tumors. Fewer HER2 CAR Ts (5 × 106) are needed to control tumors than αvβ3 CAR Ts (10 × 106), but this is not due to lack of persistence or exhaustion of αvβ3 CAR Ts. Tumor control by αvβ3 CAR Ts is delayed (>21 days) compared to that by HER2 CAR Ts (7 days), and is robust, despite initial tumor progression following treatment. Importantly, despite strong tumor control by both CAR Ts, at 7 weeks post-treatment residual tumor nests are evident by histology. At this time, CAR Ts are still abundant, are not exhausted and express memory markers, suggesting that the remaining tumor cells are no longer susceptible to CAR T killing. We are currently evaluating the hypothesis that the remaining tumor cells have down-regulated antigen expression. Delayed tumor control by αvβ3 CAR Ts was ameliorated by engineering αvβ3 overexpression in RMS tumors. Conclusions: αvβ3 and HER2 CAR Ts control orthotopic RMS tumors by distinct mechanisms with changes in αvβ3 antigen expression, likely due to tumor progression, one prevalent factor. This is consistent with our prior reports of αvβ3 CAR Ts preventing breast cancer metastases, which naturally upregulate αvβ3 compared to the primary tumor. Despite near elimination of tumors, residual nests of tumor cells are likely to rebound as CAR T resistant tumors, similar to what is seen in patients treated with monospecific CAR Ts. These data support the incorporation of αvβ3 and HER2 CAR Ts into a bispecific CAR T approach to mitigate antigen escape. Our data also support investigation into the role of αvβ3 in RMS. Citation Format: Amanda M. Lulu, Nagyeong Park, Joseph J. Caruso, Dustin A. Cobb, Daniel W. Lee. Distinct mechanisms of orthotopic tumor control by alphavbeta3and HER2 CAR Ts support development of a bispecific CAR T cell therapy for pediatric rhabdomyosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1091.

PACE: A Randomized Phase II Study of Fulvestrant, Palbociclib, and Avelumab After Progression on Cyclin-Dependent Kinase 4/6 Inhibitor and Aromatase Inhibitor for Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor-Negative Metastatic Breast Cancer.

Cyclin-dependent kinase (CDK) 4/6 inhibitors (CDK4/6is) are an important component of treatment for hormone receptor-positive/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC), but it is not known if patients might derive benefit from continuation of CDK4/6i with endocrine therapy beyond initial tumor progression or if the addition of checkpoint inhibitor therapy has value in this setting. The randomized multicenter phase II PACE trial enrolled patients with hormone receptor-positive/HER2- MBC whose disease had progressed on previous CDK4/6i and aromatase inhibitor (AI) therapy. Patients were randomly assigned 1:2:1 to receive fulvestrant (F), fulvestrant plus palbociclib (F + P), or fulvestrant plus palbociclib and avelumab (F + P + A). The primary end point was investigator-assessed progression-free survival (PFS) in patients treated with F versus F + P. Overall, 220 patients were randomly assigned between September 2017 and February 2022. The median age was 57 years (range, 25-83 years). Most patients were postmenopausal (80.9%), and 40% were originally diagnosed with de novo MBC. Palbociclib was the most common previous CDK4/6i (90.9%). The median PFS was 4.8 months on F and 4.6 months on F + P (hazard ratio [HR], 1.11 [90% CI, 0.79 to 1.55]; P = .62). The median PFS on F + P + A was 8.1 months (HR v F, 0.75 [90% CI, 0.50 to 1.12]; P = .23). The difference in PFS with F + P and F + P + A versus F was greater among patients with baseline ESR1 and PIK3CA alterations. The addition of palbociclib to fulvestrant did not improve PFS versus fulvestrant alone among patients with hormone receptor-positive/HER2- MBC whose disease had progressed on a previous CDK4/6i plus AI. The increased PFS seen with the addition of avelumab warrants further investigation in this patient population.

Radiotherapy to reinvigorate immunotherapy activity after acquired resistance in metastatic non-small-cell lung cancer: A pooled analysis of two institutions prospective phase II single arm trials

AimThe current work aimed to investigate the clinical benefit of radiotherapy in patients with metastatic non-small cell lung cancer (NSCLC) developing acquired resistance to immune checkpoint inhibitors. MethodWe report on a pooled, two-institution, phase II single-arm prospective cohort study. The study included patients with stage IV NSCLC who showed progression of one or more measurable lesions under anti-PD-(L)1 inhibition alone, after initially having achieved at least stable disease. Hypofractionated radiotherapy (hRT) of one to four metastases was performed, while one or more lesions were kept untreated. Following hRT, treatment with immune checkpoint inhibitors was continued unchanged until further evidence of tumor progression or unacceptable toxicity. Primary endpoint of the pooled analysis was progression-free survival (PFS), secondary endpoints included overall survival (OS) and toxicity. ResultsA total of 48 patients were enrolled: mean age was 67.1 ± 9.3 years, 50 % were male and 72.9 % were PD-L1 positive. Immunotherapy was in 95.8 % of patients the first or second line therapy at time of enrollment. hRT was performed to one (93.8 % of cases) or more lesions (median total dose: 27.5 Gy, median 6.5 Gy/fraction). Forty-five patients (93.8 %) were able to continue immunotherapy for a median of 6.2 months following hRT. Median PFS was 4.4 months, with 62.5 % disease control at three months and 37.5 % at six months. Median OS was 14.9 months. Severe adverse events (grade ≥ 2) were reported in 12 cases (25 %), of which none were radiotherapy-related and four were immunotherapy-related. Salvage therapy consisted of chemotherapy (48.8 %) or repeated irradiation (21.9 %). No further tumor treatment was performed in 29.3 % of patients. ConclusionsThe current pooled analysis is a prospective evaluation of the role of radiation therapy for metastatic NSCLC in the setting of newly acquired immunotherapy resistance. Hypofractionated radiotherapy can support the outcome of immune checkpoint inhibitors and thus allow continuation of treatment for a relevant amount of time despite initial tumor progression.

P11.18.B AIMING TOWARDS DIFFERENTIATING GLIOBLASTOMA PROGRESSION FROM PSEUDO PROGRESSION -PATIENTS COHORT ESTABLISHMENT AND PRELIMINARY RESULTS

Abstract BACKGROUND Longitudinal follow-up of glioblastoma patients includes advanced imaging modalities to identify tumor progression, which is of limited certainty and occasionally necessitates additional tissue sampling that has potential morbidity. Lately, the possibility of tumor-associated protein markers detection in patients' blood samples - liquid biopsies - has shown useful for this purpose in other cancers and has also gained significant interest in glioblastoma. METHODS This study presents data collected from 36histopathology-confirmed IDH-WT glioblastoma patientstreated in Sheba Medical Center between the years 2009 to 2021. Following their diagnosis, these patients were treated with radiation according to the Stupp protocol and subjected to repeated resection due to suspected tumor progressionbased on imaging studies. The data retrieved from patients' medical files include demographics, clinical outcomes, imaging characteristics, tumor molecular, andhistopathological markers. Notably, patients' selection and data retrieval were accomplished using a novel institutional AI algorithm software followed by complementary manual data retrieval of selected patients' medical files. RESULTS Patients demographics analysis showed that patientmedian age-at-diagnosis was 55.4 years (range, 21-82), and the male-to-female ratio was 3.5:1. The median overall survival (OS) was 25.1 months (range, 5.2-80.3) and the median follow-up duration was 23.1 months (range, 4.8-80.2).27 out of 36 patients had pathologically confirmed tumor progression while the remaining patients had post-radiation changes along with viable tumor or merely radiation necrosis identification. Pre-surgical resection blood samples were available for 27 out of 37 patients and will be used for a comprehensive glioblastoma-related proteins search using mass spectroscopy. In cases of patients' blood samples available both from the initial diagnosis surgical resection procedure and tumor progression surgical resection, a comparative analysis of those samples will be performed. The preliminary proteomics analysis and clinical outcomes measurements and volumetric tumor data will be presented. CONCLUSION s: Here, we present a glioblastoma patient cohort that was meticulously selected with the aim to examine our hypothesis that measuring glioblastoma-related proteins in patients' blood can be achieved and serve as a tool to distinguish between disease phases and monitor disease progression. Our comprehensive preliminary clinical, as well as proteomics data analysis, will be presented and discussed.

Diabetes increases mortality in patients with pancreatic and colorectal cancer by promoting cachexia and its associated inflammatory status

ObjectivesCancer is considered an emerging diabetes complication, with higher incidence and worse prognosis in patients with diabetes. Cancer is frequently associated with cachexia, a systemic metabolic disease causing wasting. It is currently unclear how diabetes affects the development and progression of cachexia. MethodsWe investigated the interplay between diabetes and cancer cachexia retrospectively in a cohort of 345 patients with colorectal and pancreatic cancer. We recorded body weight, fat mass, muscle mass, clinical serum values, and survival of these patients. Patients were grouped either into diabetic/non-diabetic groups based on previous diagnosis, or into obese/non-obese groups based on body mass index (BMI ≥30 kg/m2 was considered obese). ResultsThe pre-existence of type 2 diabetes, but not obesity, in patients with cancer led to increased cachexia incidence (80%, compared to 61% without diabetes, p ≤ 0.05), higher weight loss (8.9% vs. 6.0%, p ≤ 0.001), and reduced survival probability (median survival days: 689 vs. 538, Chi square = 4.96, p ≤ 0.05) irrespective of the initial body weight or tumor progression. Patients with diabetes and cancer showed higher serum levels of C-reactive protein (0.919 μg/mL vs. 0.551 μg/mL, p ≤ 0.01) and interleukin 6 (5.98 pg/mL vs. 3.75 pg/mL, p ≤ 0.05) as well as lower serum albumin levels (3.98 g/dL vs. 4.18 g/dL, p ≤ 0.05) than patients with cancer without diabetes. In a sub-analysis of patients with pancreatic cancer, pre-existing diabetes worsened weight loss (9.95% vs. 6.93%, p ≤ 0.01), and increased the duration of hospitalization (24.41 days vs. 15.85 days, p ≤ 0.001). Further, diabetes aggravated clinical manifestations of cachexia, as changes in the aforementioned biomarkers were more pronounced in patients with diabetes and cachexia co-existence, compared to cachectic patients without diabetes (C-reactive protein: 2.300 μg/mL vs. 0.571 μg/mL, p ≤ 0.0001; hemoglobin: 11.24 g/dL vs. 12.52 g/dL, p ≤ 0.05). ConclusionsWe show for the first time that pre-existing diabetes aggravates cachexia development in patients with colorectal and pancreatic cancer. This is important when considering cachexia biomarkers and weight management in patients with co-existing diabetes and cancer.

Utilizing Plasma Circulating Tumor DNA Sequencing for Precision Medicine in the Management of Solid Cancers.

Plasma circulating tumor DNA (ctDNA) sequencing has demonstrated clinical utility for tumor molecular profiling at initial diagnosis or tumor progression in advanced solid cancers and is being rapidly incorporated into the clinical practice guidelines, including non-small cell lung and breast cancer. Despite relatively low sensitivity, plasma ctDNA sequencing has several advantages over tissue-based assays, including ease of sampling, rapid turnaround time, repeatability, and the ability to overcome spatial heterogeneity, which makes it ideal for investigating acquired resistance and monitoring tumor evolution and dynamics. With technological advancement and declining costs, the clinical application of plasma ctDNA is expanding, and numerous ongoing clinical trials are examining its potential to guide the management of advanced, localized, and even preclinical cancers of various tumor types. The ability of plasma ctDNA analysis to detect minimal residual disease following curative treatment in the absence of clinical disease is among its most promising attributes. Plasma ctDNA sequencing can also facilitate the conduct of clinical trials and drug development, particularly in immunotherapy. In order to incorporate plasma ctDNA sequencing for clinical decision-making, it is important to understand the preanalytical and analytical factors that may affect its sensitivity and reliability.

Sequential Treatment Strategy Using Fluoropyrimidine plus Bevacizumab Followed by Oxaliplatin for Metastatic Colorectal Cancer: A Phase II Study (OGSG 1107)

Introduction: Previous prospective studies suggest that the sequential use of cytotoxic agents, such as oxaliplatin, in patients with metastatic colorectal cancer (mCRC) has the potential to improve prognosis and maintain quality of life than combination chemotherapy. The purpose of this study was to investigate the feasibility and effectiveness of a sequential treatment strategy consisting of an initial therapy (capecitabine, S-1, or 5-fluorouracil with leucovorin [LV/5-FU] plus bevacizumab) and subsequent therapy (i.e., initial therapy plus oxaliplatin) for mCRC. Methods: The primary endpoint was second progression-free survival (2nd PFS) between the start of initial therapy and tumor progression after sequential therapy; secondary endpoints were PFS after initial treatment, overall survival (OS), objective response rate (ORR), and safety. Results: Sixty-six patients were planned to be recruited. However, owing to a slow accrual rate, recruitment was terminated when only 19 patients were enrolled between 2011 and 2015; 4, 10, and 5 patients were administered capecitabine plus bevacizumab, S-1 plus bevacizumab, and LV/5-FU plus bevacizumab, respectively. The proportions of those with a KRAS status (wild-type/mutant/unknown) were 26%, 21%, and 53%, respectively. The median 2nd PFS and OS were 19.1 months and not reached, respectively. The ORR was 45.5% in the initial therapy and 16.7% in the subsequent therapy. Grade 3/4 toxicities included neutropenia (5%), proteinuria (5%), and hypertension (47%). Conclusion: Although our data are limited and preliminary, the sequential treatment strategy may provide a survival benefit in patients with mCRC. Further investigation of this treatment approach is warranted.

Three-year survival, correlates and salvage therapies in patients receiving first-line pembrolizumab for advanced Merkel cell carcinoma

BackgroundMerkel cell carcinoma (MCC) is an aggressive skin cancer associated with poor survival. Programmed cell death-1 (PD-1) pathway inhibitors have shown high rates of durable tumor regression compared with chemotherapy...

Molecular testing strategies in non-small cell lung cancer: optimizing the diagnostic journey.

Molecular testing identifies patients with advanced non-small cell lung cancer (NSCLC) who may benefit from targeted therapy or immunotherapy (i.e., immune checkpoint inhibitor treatment for patients with high tumor mutational burden (TMB), microsatellite instability-high or mismatch repair-deficient tumors). Current guidelines state that molecular testing should be conducted at the time of initial diagnosis and tumor progression on targeted therapy. In real-world clinical practice in the United States (US), molecular testing is often not conducted or happens late in the diagnostic journey, resulting in delayed or inappropriate treatment. Herein, we review the rationale for molecular testing in advanced NSCLC, along with best-practice guidelines based on published recommendations and our own clinical experience, including a case study. We propose three strategies to optimize molecular testing in newly diagnosed patients with advanced NSCLC: (I) pulmonologists, interventional radiologists, or thoracic surgeons order molecular tests as soon as advanced NSCLC with an adenocarcinoma component is suspected; (II) liquid biopsies conducted early in the diagnostic pathway; and (III) pathologist-directed reflex testing, as conducted in other areas of oncology. To help facilitate these strategies, we outline our recommendations for optimal sample collection techniques and stewardship. In summary, we believe that implementation of these individual strategies will allow clinicians to effectively leverage available treatment options for advanced NSCLC, reducing the time to optimal treatment and improving patient outcomes.

Five-year Long-term Outcomes of Stereotactic Body Radiation Therapy for Operable Versus Medically Inoperable Stage I Non–small-cell Lung Cancer: Analysis by Operability, Fractionation Regimen, Tumor Size, and Tumor Location

BackgroundStereotactic body radiation therapy (SBRT) is standard for medically inoperable stage I non–small-cell lung cancer (NSCLC) and is emerging as a surgical alternative in operable patients. However, limited long-term outcomes data exist, particularly according to operability. We hypothesized long-term local control (LC) and cancer-specific survival (CSS) would not differ by fractionation schedule, tumor size or location, or operability status, but overall survival (OS) would be higher for operable patients. Patients and MethodsAll consecutive patients with stage I (cT1-2aN0M0) NSCLC treated with SBRT from June 2009 to July 2013 were assessed. Thoracic surgeon evaluation determined operability. Local failure was defined as growth following initial tumor shrinkage or progression on consecutive scans. LC, CSS, and OS were calculated using Cox proportional hazards regression. ResultsA total of 186 patients (204 lesions) were analyzed. Most patients were inoperable (82%) with Eastern Cooperative Oncology Group performance status of 1 (59%) or 2 (26%). All lesions received biological effective doses ≥ 100 Gy most commonly (94%) in 3 to 5 fractions. The median follow-up was 4.0 years. LC at 2 and 5 years were 95.6% (95% confidence interval, 92%-99%) and 93.7% (95% confidence interval, 90%-98%), respectively. Compared with operable patients, inoperable patients did not have significant differences in 5-year LC (93.1% vs. 96.7%; P = .49), nodal failure (31.4% vs. 11.0%; P = .12), distant failure (12.2% vs. 10.4%; P = .98), or CSS (80.6% vs. 91.0%; P = .45) but trended towards worse OS (34.2% vs. 45.3%; P = .068). Tumor size, location, and fractionation did not significantly influence outcomes. ConclusionsSBRT has excellent, durable LC and CSS rates for early-stage NSCLC, although inoperable patients had somewhat lower OS than operable patients, likely owing to greater comorbidities.

Secreted protein acidic and rich in cysteine-like 1 suppresses metastasis in gastric stromal tumors

BackgroundMalignant growth and metastasis of gastrointestinal stromal tumors (GIST) occur in some patients even during the course of treatment, but their mechanisms remains poorly understand at the molecular level so far.MethodsProfiles of protein expression in gastric GIST tissues were explored using protein microarray analysis, down-regulation of SPARCL1 (secreted protein acidic and rich in cysteine-like protein 1) was validated by RT-qPCR, western blot and immunohistochemistry. The effect of specific shRNA-induced SPARCL1 downregulation on the biological traits of GIST 882 cell was investigated. We then employed a mouse xenograft model to investigate whether the low-expression of SPARCL1 impact the metastasis ability of GIST cells in vivo.ResultsSPARCL1 was significantly downregulated in the gastric GIST with high-grade malignance as compared with low-grade malignance, its expression was closely correlated with tumor size, mitotic index, distant metastasis at the time of initial diagnosis and tumor progression of GIST (P < 0.05). Moreover, results of the Cox analysis showed that expression of SPARCL1 is an independent prognostic predictors for gastric GIST (P = 0.008; HR 0.157, 95% CI 0.040~ 0.612). Downregulation of SPARCL1 promoted cell migration and invasion, but did not affect proliferation, cell cycle and apoptosis of GIST 882 cells. In mouse xenograft model, GIST cells with the decreased expression of SPARCL1 presented an enhanced ability of liver metastasis (P < 0.05).ConclusionsTaken together, our present study demonstrated that SPARCL1 have a certain degree of malignancy-suppressing potential through inhibiting the metastasis of gastric GIST.

Outcomes of Adoptive Cell Transfer With Tumor-infiltrating Lymphocytes for Metastatic Melanoma Patients With and Without Brain Metastases.

Brain metastases cause significant morbidity and mortality in patients with metastatic melanoma. Although adoptive cell therapy (ACT) with tumor-infiltrating lymphocytes (TIL) can achieve complete and durable remission of advanced cutaneous melanoma, the efficacy of this therapy for brain metastases is unclear. Records of patients with M1c melanoma treated with ACT using TIL, including patients with treated and untreated brain metastases, were analyzed. Treatment consisted of preparative chemotherapy, autologous TIL infusion, and high-dose interleukin-2. Treatment outcomes, sites of initial tumor progression, and overall survival were analyzed. Among 144 total patients, 15 patients with treated and 18 patients with untreated brain metastases were identified. Intracranial objective responses (OR) occurred in 28% patients with untreated brain metastases. The systemic OR rates for patients with M1c disease without identified brain disease, treated brain disease, and untreated brain disease, and were 49%, 33% and 33%, respectively, of which 59%, 20% and 16% were durable at last follow-up. The site of untreated brain disease was the most likely site of initial tumor progression (61%) in patients with untreated brain metastases. Overall, we found that ACT with TIL can eliminate small melanoma brain metastases. However, following TIL therapy these patients frequently progress in the brain at a site of untreated brain disease. Patients with treated or untreated brain disease are less likely to achieve durable systemic ORs following TIL therapy compared with M1c disease and no history of brain disease. Melanoma brain metastases likely require local therapy despite the systemic effect of ACT.

Antitumor therapeutic application of self-assembled RNAi-AuNP nanoconstructs: Combination of VEGF-RNAi and photothermal ablation.

Nucleic acid-directed self-assembly provides an attractive method to fabricate prerequisite nanoscale structures for a wide range of technological applications due to the remarkable programmability of DNA/RNA molecules. In this study, exquisite RNAi-AuNP nanoconstructs with various geometries were developed by utilizing anti-VEGF siRNA molecules as RNAi-based therapeutics in addition to their role as building blocks for programmed self-assembly. In particular, the anti-VEGF siRNA-functionalized AuNP nanoconstructs can take additional advantage of gold-nanoclusters for photothermal cancer therapeutic agent. A noticeable technical aspect of self-assembled RNAi-AuNP nanoconstructs in this study is the precise conjugation and separation of designated numbers of therapeutic siRNA onto AuNP to develop highly sophisticated RNA-based building blocks capable of creating various geometries of RNAi-AuNP nano-assemblies. The therapeutic potential of RNAi-AuNP nanoconstructs was validated in vivo as well as in vitro by combining heat generation capability of AuNP and anti-angiogenesis mechanism of siRNA. This strategy of combining anti-VEGF mechanism for depleting angiogenesis process at initial tumor progression and complete ablation of residual tumors with photothermal activity of AuNP at later tumor stage showed effective tumor growth inhibition and tumor ablation with PC-3 tumor bearing mice.

OS10 - 147 Tumor-Associated Astrocytes Promote Glioma Invasion via Cx43

Although genetic mutations are usually responsible for the initial tumor formation and progression, changes in the microenvironment also have a critical role in facilitating this process. Many ''untransformed'' cells infiltrate the tumors, and recent evidence suggests cancer cells can ‘reprogram’ normal cells by miRNAs, which are small, non-coding RNA molecules that regulate several protein targets. One prominent feature of glioma pathology is massive gliosis, an inflammatory response consisting of reactive astrocytes, in and around the tumor. We show that expression of Cx43, a major gap junction protein in astrocytes, is significantly enhanced in astrocytes at the tumor border. Using a mouse model consisting of syngeneic intracranial implantation of GL261 glioma cells into Nestin-Cre:Cx43fl/fl mice in which Cx43 is selectively eliminated in astrocytes, we demonstrate that reduction of astrocytic Cx43 decreases the dissemination of glioma cells from the tumor core. Similarly, knocking down Cx43 in astrocytes also reduces glioma invasion in a co-culture of glioma cells and astrocytes. By comparing the microRNA profiles of the astrocytes before and after co-culture with human glioma cells, we have identified a miR-5096 that appears to reprogram astrocytes to enhance the invasiveness of glioma cells. We are now examining whether we can prevent glioma cells from invading the brain and establishing recurrent secondary tumors by stopping the exchange of materials between glioma cells and astrocytes through eliminating Cx43 channel activity.

Abstract 763: Implications of resistance patterns with NSCLC targeted agents

Abstract Introduction: Tyrosine kinase inhibitors (TKIs) can give regression of NSCLCs with mutations of EGFR, HER2 &amp; BRAF and fusion genes for ALK, ROS1 &amp; RET, but resistance develops in most patients. Methods: We reviewed available clinical data for insights on potential approaches to delay resistance. Results: Target absence is a major cause of intrinsic resistance. Most NSCLCs with target undergo at least some regression although the degree varies between patients due to largely unexplored factors. Many mechanisms of acquired resistance have been defined, including outgrowth of subclones with secondary mutations or alternative pathways, and pharmacological effects &amp; sanctuaries. Available data suggest that resistant cells are present in small numbers in the initial tumor but that their growth is suppressed by the more rapidly growing parent tumor cells until this parent population is itself suppressed by TKI initiation. If TKI is stopped due to progression, there can be tumor flare as the initial parent cell population regrows rapidly. Exponential decay nonlinear regression analysis of patient survival curves suggests that TKI discontinuation at time of progression may partially “synchronize” patient deaths. Initial tumor progression may occur in a single site. Available data indicate that focal treatment (eg, radiation) to that site combined with continuation of initial TKI may give optimal control and reduce tumor flare. Of interest, progression may occur in many sites concurrently. Since there are many potential resistance mechanisms one might expect substantial discordance of resistance mechanisms between these sites, but preliminary data with 2nd line agents (eg, anti-T790M agents in EGFR-mutant patients and 2nd generation anti-ALK agents for acquired resistance to crizotinib) indicate response in most sites if any are sensitive, suggesting that all or most sites have a common resistance mechanism. This raises the possibility that an initial resistant site is seeding other distant tumor sites with resistant cells, in keeping with animal data. The probability of a resistant cell being present in an individual tumor deposit is proportional to the total number of tumor cells in that deposit. If 1 area of resistant tumor can seed other tumor areas with resistant cells, then (particularly in oligometastatic disease) we should consider clinical trials exploring: 1) at initiation of TKI therapy treating as many tumor sites as possible (particularly large tumors) with a modality (eg radiation) that is “indifferent” to the factors giving TKI resistance; 2) treating any progressing lesions as early as possible with intensive focal therapy, if feasible, rather than waiting until symptomatic or rather than treating only with low palliative doses. Conclusion: Extrapolation from available data suggests we should explore trials using multifocal radiation at initiation of TKIs for advanced NSCLC and early, intense treatment of areas of isolated progression. Citation Format: David J. Stewart, Paul Wheatley-Price, Rob MacRae, Jason Pantarotto. Implications of resistance patterns with NSCLC targeted agents. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 763. doi:10.1158/1538-7445.AM2015-763

Immune Checkpoint Blockade: A New Paradigm in Treating Advanced Cancer.

The approval of the immune checkpoint inhibitor ipilimumab for the treatment of advanced melanoma in 2011 spearheaded the development of other anticancer therapies with immune mechanisms of action, including other immune checkpoint inhibitors. Instead of acting directly on the tumor, these therapies work to "remove the brakes" on the immune system to restore antitumor immune responses. In addition to ipilimumab, which targets the cytotoxic T lymphocyte-associated antigen 4 pathway, several new drugs that target the programmed death-1 pathway are in phase III trials across tumor types, including melanoma, lung cancer, and renal cell carcinoma. In keeping with their unique mechanism of action, these immune checkpoint inhibitors have shown both conventional and unconventional response patterns, including initial apparent tumor progression followed by regression, and adverse events (AEs) that are likely immune-related. Advanced practitioners (APs) treating patients receiving immuno-oncology agents are in a key position to educate patients about expectations with these therapies and to screen patients for AEs and initiate appropriate and timely interventions. This review summarizes current immune checkpoint inhibitor data and provides patient management strategies for APs to optimize patient outcomes with these novel therapies.

Transcatheter arterial chemoembolization combined with radiofrequency ablation delays tumor progression and prolongs overall survival in patients with intermediate (BCLC B) hepatocellular carcinoma.

BackgroundThis study was designed to evaluate the effectiveness of radiofrequency ablation in patients with intermediate (BCLC B) stage hepatocellular carcinoma who underwent transcatheter arterial chemoembolization.MethodsIncluded in this study were 211 patients with intermediate stage HCC who underwent initial transcatheter arterial chemoembolization and were potentially amendable for radiofrequency ablation (single tumor with diameter 5-8 cm, median 6.0 cm; 2–5 multiple nodules with diameter less than 5 cm) between January 2005 and December 2011. According to the inclusion and exclusion criteria, 55 patients were treated with following radiofrequency ablation, and the remaining 156 patients were treated with transcatheter arterial chemoembolization alone. The treatment effectiveness, local tumor control and survival outcome between the two groups were compared.ResultsThe complete tumor necrosis rate after treatment was 76.9% in combination group vs. 46.5% in transcatheter arterial chemoembolization alone group (P = 0.02). The major complication rate was 1.8% in combination group vs. 2.6% in transcatheter arterial chemoembolization alone group. Follow-up observation showed that the total tumor control rate was 74.5% in combination group versus 54.5% in transcatheter arterial chemoembolization alone group (P < 0.001). The 1-, 3- and 5-year survival rates in combination group were significantly higher than those in TACE alone group (P = 0.01).ConclusionsRadiofrequency ablation following initial transcatheter arterial chemoembolization delays tumor progression and prolongs overall survival of patients with intermediate stage HCC tumors.

Dynamic dialog between cytokeratin 18 and annexin A1 in breast cancer: A transcriptional disequilibrium

Cytokeratins (CKs) constitute the cytoskeletal network and are regulated by post-translational modifications, acting not only as a mechanical support, but also in cell signaling and regulatory processes. Signaling is mediated by CK-associated proteins, such as Annexin A1 (ANXA1), a ligand of the CK18/CK8 complex. ANXA1 has a pivotal role in cellular and immunological responses, and together with CK18 have been implicated in several processes related to malignant transformation in breast cancer (BC). Our aim was to demonstrate how their interaction might be linked to BC development. We investigated transcript levels, protein expression and distribution for both targets in breast tissues of 92 patients (42 BCs and 50 benign diseases) using qPCR and immunohistochemistry, respectively. ANXA1 and CK18 mRNAs were inversely correlated, and their ratio in each TNM stage significantly differentiated BC from benign diseases (OR=5.62). These differences did not mirror tissue protein levels, but a significant dichotomous protein distribution in tumor tissues was observed, differing from the expected co-localization observed during cell homeostasis. The disequilibrium of transcriptional levels between ANXA1/CK18 and alterations in their tissue distribution are present either in initial events or tumor progression, which suggest a critical event in BC. The broken dialog between ANXA1 and CK18 in normal breast tissues may play a critical role in BC development, and together may be used as combined targets for BC diagnostics.

Tryptophan PET-defined gross tumor volume offers better coverage of initial progression than standard MRI-based planning in glioblastoma patients.

Glioblastoma is an infiltrative malignancy that tends to extend beyond the MRI-defined tumor volume. We utilized positron emission tomography (PET) imaging with the radiotracer alpha-[11C]methyl-L -tryptophan (AMT) to develop a reliable high-risk gross tumor volume (HR-GTV) method for delineation of glioblastoma. AMT can detect solid tumor mass and tumoral brain infiltration by increased tumoral tryptophan transport and metabolism via the immunosuppressive kynurenine pathway. We reviewed all patients in our database with histologically proven glioblastoma who underwent preoperative AMT-PET scan prior to surgery and chemoradiation. Treated radiotherapy volumes were derived from the simulation CT with MRI fusion. High-GTV with contrast enhanced T1-weighted MRI alone (GTVMRI) was defined as the postoperative cavity plus any residual area of enhancement on postcontrast T1-weighted images. AMT-PET images were retrospectively fused to the simulation CT, and a high-risk GTVs generated by both AMT-PET alone (GTVAMT) was defined using a threshold previously established to distinguish tumor tissue from peritumoral edema. A composite volume of MRI and AMT tumor volume was also created (combination of MRI fused with AMT-PET data; GTVMRI+AMT). In patients with definitive radiographic progression, follow-up MRI demonstrating initial tumor progression was fused with the pretreatment images and a progression volume was contoured. The coverage of the progression volume by GTVMRI, GTVAMT, and GTVMRI+AMT was determined and compared using the Wilcoxon's signed-rank test. Eleven patients completed presurgical AMT-PET scan, seven of whom had progressive disease after initial therapy. GTVMRI (mean, 50.2 cm3) and GTVAMT (mean, 48.9 cm3) were not significantly different. Mean concordance index of the volumes was 39±15 %. Coverage of the initial recurrence volume by HR-GTVMRI (mean, 52 %) was inferior to both GTVAMT (mean, 68 %; p =0.028) and GTVMRI+AMT (mean 73 %; p =0.018). The AMT-PET-exclusive coverage was up to 41 % of the recurrent volume. There was a tendency towards better recurrence coverage with GTVMRI+AMT than with GTVAMT alone (p =0.068). Addition of 5 mm concentric margin around GTVMRI, GTVAMT, and GTVMRI+AMT would have completely covered the initial progression volume in 14, 57, and 71 % of the patients, respectively. We found that a GTV defined by AMT-PET produced similar volume, but superior recurrence coverage than the treated standard MRI-determined volume. A prospective study is necessary to fully determine the usefulness of AMT-PET for volume definition in glioblastoma radiotherapy planning.

Bevacizumab and etoposide combination chemotherapy in patients with recurrent malignant gliomas who failed bevacizumab

Bevacizumab is the current standard of care treatment for recurring malignant glioma patients. However, most of the tumors become resistant to bevacizumab, and there is no standardized, effective chemotherapy for the malignant glioma patients after bevacizumab failure. Retrospective chart review was performed in order to identify the malignant glioma patients treated with oral, metronomic etoposide in combination with bevacizumab after being diagnosed with progressive disease while on bevacizumab. This review was approved by the Institutional Review Board (IRB) of the University of California, Irvine. Six malignant gliomas patients met the inclusion criteria. The median progression-free survival (PFS) for the anaplastic astrocytoma (AA) patients was eight months, and the overall survival was 28 months. The two Glioblastoma Multiforme (GBM) patients showed tumor progression after four to eight weeks of treatment with bevacizumab and etoposide, and died within four months of beginning the etoposide/bevacizumab regimen. In this limited study, patients with AA demonstrated prolonged control on combination treatment with bevacizumab and oral etoposide, despite initial tumor progression on bevacizumab. These results may warrant further investigation on a prospective clinical trial of this combination in AA patients who developed resistance to bevacizumab.