Phase II study (KAMELEON) of single-agent T-DM1 in patients with HER2-positive advanced urothelial bladder cancer or pancreatic cancer/cholangiocarcinoma

The antibody-drug conjugate trastuzumab emtansine (T-DM1) is approved for human epidermal growth factor receptor 2 (HER2/ERBB2)-positive breast cancer. We aimed to study tumor HER2 expression and its effects on T-DM1 responses in patients with HER2-positive urothelial bladder cancer (UBC) or pancreatic cancer (PC)/cholangiocarcinoma (CC). In the phase II KAMELEON study (NCT02999672), HER2 status was centrally assessed by immunohistochemistry, with positivity defined as non-focal homogeneous or heterogeneous overexpression of HER2 in ≥30% of stained cells. We also performed exploratory biomarker analyses (e.g., gene-protein assay) on tissue samples collected from study participants and consenting patients who failed screening. Of the 284 patients successfully screened for HER2 status (UBC, n = 69; PC/CC, n = 215), 13 with UBC, four with PC, and three with CC fulfilled eligibility criteria. Due to recruitment difficulty, the sponsor terminated KAMELEON prematurely. Of the five responders in the UBC cohort (overall response rate, 38.5%), HER2 expression was heterogeneous in two and homogeneous in three. The one responder in the PC/CC cohort had PC, and the tumor displayed homogeneous expression. In the biomarker-evaluable population, composed of screen-failed and enrolled patients, 24.3% (9/37), 1.5% (1/66), and 8.2% (4/49) of those with UBC, PC, or CC, respectively, had HER2-positive tumors. In a gene-protein assay combining in situ hybridization with immunohistochemistry, greater HER2 homogeneity was associated with increased ERBB2 amplification ratio. In conclusion, KAMELEON showed that some patients with HER2-positive UBC or PC can respond to T-DM1 and provided insight into the prevalence of HER2 positivity and expression patterns in three non-breast tumor types.

Genome-wide aneuploidy detected by mFast-SeqS in circulating cell-free DNA is associated with poor response to pembrolizumab in patients with advanced urothelial cancer

Second-line treatment with immune checkpoint inhibition in patients with metastatic urothelial cancer (mUC) has a low success rate (~ 20%). Circulating tumour-derived DNA (ctDNA) levels may guide patient stratification, provided that an affordable and robust assay is available. Here, we investigate whether the modified fast aneuploidy screening test-sequencing system (mFast-SeqS) may provide such an assay. To this end, mFast-SeqS was performed on cell-free DNA (cfDNA) from 74 patients with mUC prior to treatment with pembrolizumab. Results were associated with corresponding tissue-based profiles, plasma-based variant allele frequencies (VAFs) and clinical response. We found that plasma-derived mFast-SeqS-based aneuploidy scores significantly correlated with those observed in the corresponding tumour tissue as well as with the ctDNA level in the plasma. In multivariate logistic regression analysis, a high aneuploidy score was independently associated with lack of clinical benefit from treatment with pembrolizumab. In conclusion, mFast-SeqS provides a patient-friendly, high-throughput and affordable method to estimate ctDNA level. Following independent validation, this test could be used to stratify mUC patients for response prior to the initiation of treatment with pembrolizumab.

Phase I/IIa Trial of BMS-986148, an Anti-mesothelin Antibody-drug Conjugate, Alone or in Combination with Nivolumab in Patients with Advanced Solid Tumors

PURPOSE

To assess the safety and tolerability of BMS-986148, a mesothelin-directed antibody-drug conjugate (ADC) ± nivolumab, in patients with selected tumors.

PATIENTS AND METHODS

In an international phase I/IIa study [NCT02341625 (CA008-002)], patients received BMS-986148 monotherapy (0.1-1.6 mg/kg intravenously (i.v.) every 3 weeks or 0.4 or 0.6 mg/kg i.v. once weekly; n = 96) or BMS-986148 0.8 mg/kg + nivolumab 360 mg i.v. every 3 weeks (n = 30). The primary endpoint was safety and tolerability.

RESULTS

In CA008-002, the most common (≥ 10%) treatment-related adverse events (TRAEs) included increased aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase. Grade 3/4 TRAEs occurred in 42 patients (49%) receiving BMS-986148 every 3 weeks monotherapy, three (25%) receiving BMS-986148 once-weekly monotherapy, and 10 (33%) receiving BMS-986148 + nivolumab every 3 weeks. Overall, 17 of 126 patients (13%) discontinued because of a TRAE. The MTD of BMS-986148 was 1.2 mg/kg i.v. every 3 weeks. The safety profile of BMS-986148 + nivolumab was similar to that of BMS-986148 monotherapy (0.8 mg/kg). Active ADC exposures increased in a dose-proportional manner with both dosing regimens (every 3 weeks and once weekly). Preliminary clinical activity was observed with BMS-986148 ± nivolumab. No association between mesothelin expression and response was detected.

CONCLUSIONS

BMS-986148 ± nivolumab demonstrated a clinically manageable safety profile and preliminary evidence of clinical activity, supporting additional studies combining directed cytotoxic therapies with checkpoint inhibitors as potential multimodal therapeutic strategies in patients with advanced solid tumors.

Combined Longitudinal Clinical and Autopsy Phenomic Assessment in Lethal Metastatic Prostate Cancer: Recommendations for Advancing Precision Medicine

BACKGROUND

Systematic identification of data essential for outcome prediction in metastatic prostate cancer (mPC) would accelerate development of precision oncology.

OBJECTIVE

To identify novel phenotypes and features associated with mPC outcome, and to identify biomarker and data requirements to be tested in future precision oncology trials.

DESIGN SETTING AND PARTICIPANTS

We analyzed deep longitudinal clinical, neuroendocrine expression, and autopsy data of 33 men who died from mPC between 1995 and 2004 (PELICAN33), and related findings to mPC biomarkers reported in the literature.

INTERVENTION

Thirty-three men prospectively consented to participate in an integrated clinical-molecular rapid autopsy study of mPC.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Data exploration with correction for multiple testing and survival analysis from the time of diagnosis to time to death and time to first occurrence of severe pain as outcomes were carried out. The effect of seven complications on the modeled probability of dying within 2 yr after presenting with the complication was evaluated using logistic regression.

RESULTS AND LIMITATIONS

Feature exploration revealed novel phenotypes related to mPC outcome. Four complications (pleural effusion, severe anemia, severe or controlled pain, and bone fracture) predict the likelihood of death within 2 yr. Men with Gleason grade group 5 cancers developed severe pain sooner than those with lower-grade tumors. Surprisingly, neuroendocrine (NE) differentiation was frequently observed in the setting of high serum prostate-specific antigen (PSA) levels (≥30 ng/ml). In 4/33 patients, no controlled (requiring analgesics) or severe pain was detected, and strikingly, 14/15 metastatic sites studied in these men did not express NE markers, suggesting an inverse relationship between NE differentiation and pain in mPC. Intracranial subdural metastasis is common (36%) and is usually clinically undetected. Categorization of "skeletal-related events" complications used in recent studies likely obscures the understanding of spinal cord compression and fracture. Early death from prostate cancer was identified in a subgroup of men with a low longitudinal PSA bandwidth. Cachexia is common (body mass index <0.89 in 24/31 patients) but limited to the last year of life. Biomarker review identified 30 categories of mPC biomarkers in need of winnowing in future trials. All findings require validation in larger cohorts, preferably alongside data from this study.

CONCLUSIONS

The study identified novel outcome subgroups for future validation and provides "vision for mPC precision oncology 2020-2050" draft recommendations for future data collection and biomarker studies.

PATIENT SUMMARY

To better understand variation in metastatic prostate cancer behavior, we assembled and analyzed longitudinal clinical and autopsy records in 33 men. We identified novel outcomes, phenotypes, and aspects of disease burden to be tested and refined in future trials.

Abstract PO-019: Radiotherapy in cancer is associated with a deletion signature that contributes to poor patient outcomes

Diffuse gliomas are highly aggressive brain tumors that invariably relapse despite treatment with chemo- and radiotherapy. Treatment with alkylating chemotherapy can drive tumors to develop a hypermutator phenotype. In contrast, the genomic effects of radiation therapy (RT) remain unknown. We analyzed the mutational spectra following treatment with ionizing radiation in sequencing data from 190 paired primary-recurrent gliomas from the Glioma Longitudinal Analysis (GLASS) dataset and 3693 post-treatment metastatic tumors from the Hartwig Medical Foundation (HMF). We identified a significant increase in the burden of small deletions following radiation therapy that was independent of other factors. These novel deletions demonstrated distinct characteristics when compared to pre-existing deletions present prior to RT-treatment and deletions in RT-untreated tumors. Radiation therapy-acquired deletions were characterized by a larger deletion size (GLASS and metastatic cohort, P=1.2e-02 and P=8e-11, respectively; Mann-Whitney U test), an increased distance to repetitive DNA elements (P&lt;2.2e-16, Kolmogorov-Smirnov test) and a reduction in microhomology at breakpoints (P=3.2e-02, paired Wilcoxon signed-rank test). These observations suggested that canonical non-homologous end joining (c-NHEJ) was the preferred pathway for DNA double strand break repair of RT-induced DNA damage. Furthermore, radiotherapy resulted in frequent chromosomal deletions and significantly increased frequencies of CDKN2A homozygous deletions. Finally, a high burden of RT-associated deletions was associated with worse clinical outcomes (GLASS and metastatic cohort, P &lt; 1e-04 and P = 2.6e-02, respectively; Wald test). Our results suggest that effective repair of RT-induced DNA damage is detrimental to patient survival and that inhibiting c-NHEJ may be a viable strategy for improving the cancer-killing effect of radiotherapy. Taken together, the identified genomic scars as a result of radiation therapy reflect a more aggressive tumor with increased levels of resistance to follow up treatments.

Citation Format: Emre Kocakavuk, Kevin J. Anderson, Frederick S. Varn, Kevin C. Johnson, Samirkumar B. Amin, Erik. P. Sulman, Martijn Lolkema, Floris P. Barthel, Roel G.W. Verhaak. Radiotherapy in cancer is associated with a deletion signature that contributes to poor patient outcomes [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-019.

Detection of tumor-derived extracellular vesicles in plasma from patients with solid cancer

Background

Extracellular vesicles (EVs) are actively secreted by cells into body fluids and contain nucleic acids of the cells they originate from. The goal of this study was to detect circulating tumor-derived EVs (ctEVs) by mutant mRNA transcripts (EV-RNA) in plasma of patients with solid cancers and compare the occurrence of ctEVs with circulating tumor DNA (ctDNA) in cell-free DNA (cfDNA).

Methods

For this purpose, blood from 20 patients and 15 healthy blood donors (HBDs) was collected in different preservation tubes (EDTA, BCT, CellSave) and processed into plasma within 24 h from venipuncture. EVs were isolated with the ExoEasy protocol from this plasma and from conditioned medium of 6 cancer cell lines and characterized according to MISEV2018-guidelines. RNA from EVs was isolated with the ExoRNeasy protocol and evaluated for transcript expression levels of 96 genes by RT-qPCR and genotyped by digital PCR.

Results

Our workflow applied on cell lines revealed a high concordance between cellular mRNA and EV-RNA in expression levels as well as variant allele frequencies for PIK3CA, KRAS and BRAF. Plasma CD9-positive EV and GAPDH EV-RNA levels were significantly different between the preservation tubes. The workflow detected only ctEVs with mutant transcripts in plasma of patients with high amounts (> 20%) of circulating tumor DNA (ctDNA). Expression profiling showed that the EVs from patients resemble healthy donors more than tumor cell lines supporting that most EVs are derived from healthy tissue.

Conclusions

We provide a workflow for ctEV detection by spin column-based generic isolation of EVs and PCR-based measurement of gene expression and mutant transcripts in EV-RNA derived from cancer patients’ blood plasma. This workflow, however, detected tumor-specific mutations in blood less often in EV-RNA than in cfDNA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08007-z.

291 Phase Ib study of selicrelumab (CD40 agonist) in combination with atezolizumab (anti-PD-L1) in patients with advanced solid tumors

Background

Selicrelumab is a human IgG2 agonistic anti-CD40 monoclonal antibody. Binding of the antibody to CD40 expressed on antigen-presenting cells results in T- cell priming and T-cell dependent anti-tumor activity. In response to T-cell activation, tumor cells express programmed-death ligand 1 (PD-L1) that can suppress effector T-cells. Atezolizumab interrupts this feedback loop by blocking PD-L1, thereby supporting the combination with selicrelumab.

Methods

This phase Ib open-label, multicenter, dose escalation (DE)/expansion clinical study (NCT02304393) investigated safety, pharmacokinetic (PK), pharmacodynamics (PD) and efficacy of selicrelumab in combination with atezolizumab in unselected patients with advanced/metastatic solid tumors, not amenable to standard therapy. In DE cohorts, a single dose of selicrelumab was given, either by intravenous (IV) infusion at a 16 mg fixed dose or subcutaneously (SC) at a range from 1 to 64 mg/dose. In dose-expansion cohorts (small bowel and colorectal cancer, head and neck squamous cell carcinoma [HNSCC] and non-small cell lung carcinoma), patients received multiple doses of selicrelumab SC at a dose of 16 mg. In all treatment cohorts, patients received atezolizumab at a fixed dose of 1200 mg IV Q3W.

Results

In this study, 140 patients were treated. This included 95 patients in DE cohorts (6 patients in the IV cohort, 89 patients in the SC cohorts) and 45 patients in dose-expansion cohorts. In the IV cohort, infusion related reaction was the most frequent treatment-related adverse event (TRAE; 50%), while Grade ≥ 3 TRAE occurred in 1 patient (16.7%). In this cohort one dose-limiting toxicity (DLT) was reported (Grade 3 pancytopenia). In the SC cohorts, the most frequent TRAE was injection site reaction (ISR; 92%). Four DLTs were reported in four patients: three Grade 3 ISR and one Grade 3 transaminase increase. Grade ≥ 3 TRAE were reported in 22 patients (16.4%). Anti-tumor activity was observed across cohorts receiving SC selicrelumab (dose range 1 to 36 mg). Eight of 80 evaluable patients in DE cohorts experienced objective responses (9% ORR). In the dose-expansion HNSCC cohort, three of 16 evaluable patients responded (15.8% ORR). There were no objective responses in the IV cohort. Treatment with selicrelumab resulted in significant peripheral B-cell depletion and activation and CD8+ T cell proliferation.

Conclusions

Treatment with selicrelumab in combination with atezolizumab was well tolerated in patients with advanced solid tumors. Signals of clinical and PD activity were observed. However, efficacy of the combination in this unselected population was limited, when compared to monotherapy efficacy of atezolizumab.

Trial Registration

NCT02304393

Ethics Approval

This study was approved by the local IRB at each participating study site.

Bridging the Translational Divide in Oncology: In Vivo Testing of Chemo-sensitivity

A study was presented in which sarcomas were microinjected simultaneously with several drugs to study the pharmacodynamic response after resection. This platform may represent a future way of probing efficacy of anticancer agents in the relevant model system: human tumors.

See related article by Gundle et al., p. 3958

Abstract PL04-01: Background and use of circulating tumor-derived DNA and circulating tumor cells as biomarkers

The use of circulating biomarkers to assess malignant disease is an ever growing field of interest. Indeed, many studies have shown that mutations derived from tumors can be detected in plasma, and the use of novel sequencing techniques have given rise to many novel ways of probing blood samples for analytes that may reveal tumor characteristics. In my presentation I will present some crucial pieces of evidence that circulating tumor-derived DNA (ctDNA) may be used to detect minimal residual disease, track mutational evolution and may be used to monitor disease response to treatment. Indeed, ctDNA is one of the most promising analytes and has the potential to alter clinical practice in the foreseeable future. But to get there we need to have a basic understanding of the variables that determine the outcome of these tests. Pre-analytical conditions and proper controls for ctDNA quantification are crucial in the interpretation of the results. Seemingly trivial factors such as intrinsic variation of cfDNA may affect the way we can use this type of analyte. Moreover, I will give an overview of those tests that are about to become available in the coming years, including shallow whole genome sequencing, methylation specific sequencing and panel based sequencing of ctDNA. The second part of my presentation will deal with the first true circulating biomarker that has been the detection of Circulating Tumor Cells (CTCs) and still detecting CTCs is important for the oncology community. I will review the advances we made in this field and will dive a bit deeper into the reasons why we still should be looking at CTCs. In contrast to non-cellular analytes, CTCs can inform us on properties of cells as a whole. The technology development in this arena made enormous advances and the use of single cell sequencing techniques will revolutionize our understanding of intra-tumoral heterogeneity from relatively simple blood based tests. Moreover, the detection of CTCs has always been hampered by the relative low abundance of CTCs, however novel approaches such as leukapheresis to isolate CTCs may deliver on the promise characterization of CTCs holds to reveal the extent of tumor cell heterogeneity.

Citation Format: Martijn Lolkema. Background and use of circulating tumor-derived DNA and circulating tumor cells as biomarkers [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr PL04-01. doi:10.1158/1535-7163.TARG-19-PL04-01

Abstract B057: BMS-986148, an anti-mesothelin antibody-drug conjugate (ADC), alone or in combination with nivolumab demonstrates clinical activity in patients with select advanced solid tumors

Background: Mesothelin, a GPI-anchored cell surface protein, is highly expressed in several tumor types and can be targeted for antibody (ab)-based cancer therapy. BMS-986148 is a fully human IgG1 anti-mesothelin monoclonal ab conjugated to tubulysin to promote selective cytotoxic delivery to tumor cells. In preclinical models, combination of anti–mesothelin-tubulysin with anti–PD-1 promoted a synergistic antitumor response and influx of tumor-infiltrating lymphocytes. Here, we present initial data for BMS-986148 ± nivolumab (NIVO; anti–PD-1) from a phase 1/2a trial in a biomarker-defined population of patients (pts) with select advanced solid tumors (NCT02341625). Methods: During dose escalation (ESC), pts received BMS-986148 0.1 to 1.6 mg/kg IV Q3W, BMS-986148 0.4 or 0.8 mg/kg IV Q1W, or BMS-986148 0.8 mg/kg + NIVO 360 mg IV Q3W. During monotherapy (mono) dose expansion (EXP), pts with mesothelin-selected mesothelioma (ie, H score ≥ 100 for tumor mesothelin expression), non-small cell lung cancer (NSCLC), or ovarian cancer received BMS-986148 1.2 mg/kg mono IV Q3W, and during combination (combo) dose EXP, pts with mesothelin-selected mesothelioma or pancreatic cancer received BMS-986148 0.8 mg/kg + NIVO 360 mg combo IV Q3W. The primary endpoint was safety. Secondary endpoints included pharmacokinetics (PK) and antitumor activity. Results: As of April 1, 2019, 126 pts have been treated in this trial; 96 pts received BMS-986148 mono (Q3W, n = 84; Q1W, n = 12), and 30 pts received BMS-986148 + NIVO combo. PK analysis in pts treated during ESC demonstrated that total antibody and active ADC exposures increased in a dose-proportional manner. Unconjugated tubulysin concentrations were low but sustained over the dosing interval. The maximum tolerated dose (MTD) for mono was 1.2 mg/kg Q3W, and the 0.8 mg/kg dose was determined to be tolerable for the combo. Across all cohorts, any-grade and grade 3/4 treatment-related AEs (TRAEs) were reported in 87% and 44% of all pts, respectively. Overall, the most common TRAEs (any grade; grade 3-4) reported in ≥ 15% of pts were AST increased (43%; 17%), ALT increased (41%; 16%), fatigue (37%; 5%), nausea (29%; 0%), decreased appetite (22%; 1%), and blood alkaline phosphatase increased (18%; 4%). The frequency of TRAEs and dose-limiting toxicities related to liver function tests increased with increasing dose of BMS-986148. Most TRAEs resolved with dose interruption, dose reduction, or treatment discontinuation. Serious TRAEs were reported in 18% of pts with mono and 23% of pts with combo. Fifteen percent of pts discontinued due to TRAEs, and 1 pt died due to a TRAE (pneumonitis; 1.2 mg/kg Q3W mono). The ORR was 6% (0 CR, 3 PR) with mono in EXP and 20% (0 CR, 6 PR) with the combo in ESC and EXP. Among pts with mesothelioma, the ORR was 4% with mono in EXP and 31% with combo in ESC and EXP. Among pts with ovarian carcinoma, the ORR was 9% with mono in EXP. Of note, durable responses lasting up to ≈ 20 mo in pts with ovarian cancer with mono and ≈ 9 mo in pts with mesothelioma with mono and combo were observed. Conclusions: BMS-986148 ± NIVO was tolerable and demonstrated a clinically manageable safety profile. Preliminary clinical activity was observed with BMS-986148 ± NIVO in select patient populations, including pts with mesothelioma.

Citation Format: Jeffrey Clarke, Siu-Chung Chu, Lillian L Siu, Jean-Pascal Machiels, Benjamin Markman, Kimberley Heinhuis, Michael Millward, Martijn Lolkema, Sandip Pravin Patel, Paul de Souza, Giuseppe Curigliano, Armando Santoro, Michelle Brown, Ronald Fleming, Heather Vezina, Chunsheng He, Sylvie Rottey. BMS-986148, an anti-mesothelin antibody-drug conjugate (ADC), alone or in combination with nivolumab demonstrates clinical activity in patients with select advanced solid tumors [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr B057. doi:10.1158/1535-7163.TARG-19-B057

SAT-LB002 Steroid Metabolome Analysis Reveals 11-Ketotestosterone as the Most Abundant Androgen in Castration-Resistant Prostate Cancer Patients on Second-Line Therapies

Introduction Metastatic castration-resistant prostate cancer (CRPC) remains a clinical challenge despite antitumoral therapies such as taxane chemotherapeutics, enzalutamide, and abiraterone acetate. Clinical studies have highlighted the benefits of these therapies on overall and progression-free survival, but the changes these treatments impose on the steroid metabolome have not yet been fully mapped. In this study, we investigated the steroid metabolomes of CRPC patients on second-line therapies before and during treatment and after clinical progression was observed. Method Plasma samples from 30 patients from the ongoing CIRCUS trial were selected. Patients were included if progression on androgen-deprivation therapy was confirmed and patients were scheduled to receive additional secondary treatment with antiandrogens (enzalutamide (n=10) or apalutamide (n=1)), abiraterone + prednisone (n=2), docetaxel + prednisone (DP, n=10) or cabazitaxel + prednisone (CP, n=14). Seven patients completed two treatments during their enrollment in CIRCUS. Following liquid-liquid extraction of steroids from plasma, multi-steroid profiling by liquid chromatography-tandem mass spectrometry was carried out targeting 16 steroid hormones from classic and 11-oxygenated androgen pathways as well as mineralocorticoid and glucocorticoid biosynthetic pathways. Results Accurate quantification was achieved for all targeted steroids with the exception of dihydrotestosterone and androstenedione. The most abundant active androgen in CRPC patients was 11-ketotestosterone (11KT) with a median concentration of 0.46 nM (range 0.03 - 2.39 nM), whereas the median testosterone concentration was 0.14 nM (range 0.03 - 0.76 nM). 11KT and its precursors were suppressed by CP treatment. Analysis of all patients who started treatment with glucocorticoids revealed a potent suppression of 11KT by 88.5% (range 17.9 - 97.5%) and testosterone by 70.1% (range 24.1 - 95%), as well as suppression of 11-oxygenated androgen precursor steroids. Increased 11KT levels were observed in the DP-treated patients at the time of progressive disease. Discussion In this study, we present in-depth characterization of the previously unexplored steroid metabolomes in CRPC patients revealing 11KT as the most abundant androgen. 11KT has been shown to bind and activate the AR with similar potency to testosterone and our findings suggest that the 11-oxygenated androgens may be the dominant AR agonists in the CRPC setting. Routine quantification of testosterone alone may therefore underestimate the androgenic potential in CRPC patients. Suppression of adrenal androgens, including 11KT, was achieved by glucocorticoid treatment, which may explain the beneficial effects of glucocorticoids in CRPC patients. Funding This project was funded by the Daniel den Hoed foundation. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.

A phase I study of the HDM2 antagonist SAR405838 combined with the MEK inhibitor pimasertib in patients with advanced solid tumours

BACKGROUND

This phase I, open-label, dose-escalation study evaluated the safety, pharmacokinetics and pharmacodynamics of combination therapy with the HDM2 inhibitor SAR405838 and the MEK1/2 inhibitor pimasertib administered orally once daily (QD) or twice daily (BID) in locally advanced or metastatic solid tumours (NCT01985191).

METHODS

Patients with locally advanced or metastatic solid tumours with documented wild-type TP53 and RAS or RAF mutations were enroled. A 3 + 3 dose-escalation design was employed. The primary objective was to assess maximum tolerated dose (MTD).

RESULTS

Twenty-six patients were treated with SAR405838 200 or 300 mg QD plus pimasertib 60 mg QD or 45 mg BID. The MTD was SAR405838 200 mg QD plus pimasertib 45 mg BID. The most common dose-limiting toxicity was thrombocytopenia. The most frequently occurring treatment-related adverse events were diarrhoea (81%), increased blood creatine phosphokinase (77%), nausea (62%) and vomiting (62%). No significant drug-drug interactions were observed. The biomarkers MIC-1 and pERK were, respectively, upregulated and downregulated in response to study treatment. In 24 efficacy-evaluable patients, one patient (4%) had a partial response and 63% had stable disease.

CONCLUSIONS

The safety profile of SAR405838 and pimasertib combined was consistent with the safety profiles of both drugs. Preliminary antitumour activity was observed.

Necuparanib, A Multitargeting Heparan Sulfate Mimetic, Targets Tumor and Stromal Compartments in Pancreatic Cancer

Pancreatic cancer has an abysmal 5-year survival rate of 8%, making it a deadly disease with a need for novel therapies. Here we describe a multitargeting heparin-based mimetic, necuparanib, and its antitumor activity in both in vitro and in vivo models of pancreatic cancer. Necuparanib reduced tumor cell proliferation and invasion in a three-dimensional (3D) culture model; in vivo, it extended survival and reduced metastasis. Furthermore, proteomic analysis demonstrated that necuparanib altered the expression levels of multiple proteins involved in cancer-driving pathways including organ development, angiogenesis, proliferation, genomic stability, cellular energetics, and invasion and metastasis. One protein family known to be involved in invasion and metastasis and altered by necuparanib treatment was the matrix metalloprotease (MMP) family. Necuparanib reduced metalloproteinase 1 (MMP1) and increased tissue inhibitor of metalloproteinase 3 (TIMP3) protein levels and was found to increase RNA expression of TIMP3. MMP enzymatic activity was also found to be reduced in the 3D model. Finally, we confirmed necuparanib's in vivo activity by analyzing plasma samples of patients enrolled in a phase I/II study in patients with metastatic pancreatic cancer; treatment with necuparanib plus standard of care significantly increased TIMP3 plasma protein levels. Together, these results demonstrate necuparanib acts as a broad multitargeting therapeutic with in vitro and in vivo anti-invasive and antimetastatic activity.

Testosterone Diminishes Cabazitaxel Efficacy and Intratumoral Accumulation in a Prostate Cancer Xenograft Model

Inactivation of the androgen receptor (AR) pathway by androgen deprivation therapy (ADT) is the mainstay of (metastatic) prostate cancer therapy. Ultimately, the AR pathway will be re-activated despite castrate levels of circulating androgens. Thereby, maintaining its role even in castration resistant prostate cancer (CRPC). The recent STAMPEDE and CHAARTED trials showed that docetaxel in combination with ADT increased survival in hormone sensitive prostate cancer patients, suggesting cross-talk between AR signaling and chemotherapy efficacy. We hypothesized that a similar interaction may also apply for CRPC that is treated with cabazitaxel. We studied the impact of androgen status on the efficacy, pharmacodynamics and -kinetics of cabazitaxel in a unique and clinically relevant patient derived xenograft model of castration resistant disease. We found that cabazitaxel is highly effective in a castrate setting with strongly reduced AR activation, while tumor growth inhibition by cabazitaxel was completely abolished in the presence of high AR pathway activity. Moreover, additional experiments showed that intratumoral cabazitaxel levels were 3.5 times higher in tumors from castrated mice as compared to tumors from androgen-supplemented animals. We confirmed that cabazitaxel pharmacokinetics were not affected by testosterone, suggesting that androgen status might influence cabazitaxel tumor uptake directly. This study reveals the impact of androgen status on cabazitaxel efficacy and supports the potential of combination of taxane chemotherapeutics with AR axis targeting agents.

Intravital characterization of tumor cell migration in pancreatic cancer

Curing pancreatic cancer is difficult as metastases often determine the poor clinical outcome. To gain more insight into the metastatic behavior of pancreatic cancer cells, we characterized migratory cells in primary pancreatic tumors using intravital microscopy. We visualized the migratory behavior of primary tumor cells of a genetically engineered pancreatic cancer mouse model and found that pancreatic tumor cells migrate with a mesenchymal morphology as single individual cells or collectively as a stream of non-cohesive single motile cells. These findings may improve our ability to conceive treatments that block metastatic behavior.

The use of circulating tumor cells in guiding treatment decisions for patients with metastatic castration-resistant prostate cancer

The therapeutic landscape of metastatic castration-resistant prostate cancer (mCRPC) has drastically changed over the past decade with the advent of several new anti-tumor agents. Oncologists increasingly face dilemmas concerning the best treatment sequence for individual patients since most of the novel compounds have been investigated and subsequently positioned either pre- or post-docetaxel. A currently unmet need exists for biomarkers able to guide treatment decisions and to capture treatment resistance at an early stage thereby allowing for an early change to an alternative strategy. Circulating tumor cells (CTCs) have in this context intensively been investigated over the last years. The CTC count, as determined by the CellSearch System (Janssen Diagnostics LLC, Raritan, NJ), is a strong, independent prognostic factor for overall survival in patients with mCRPC at various time points during treatment and, as an early response marker, outperforms traditional response evaluations using serum prostate specific antigen (PSA) levels, scintigraphy as well as radiography. The focus of research is now shifting toward the predictive value of CTCs and the use of the characterization of CTCs to guide the selection of treatments with the highest chance of success for individual patients. Recently, the presence of the androgen receptor splice variant 7 (AR-V7) has been shown to be a promising predictive factor. In this review, we have explored the clinical value of the enumeration and characterization of CTCs for the treatment of mCRPC and have put the results obtained from recent studies investigating the prognostic and predictive value of CTCs into clinical perspective.

Phase I study of olaparib in combination with carboplatin and/or paclitaxel in patients with advanced solid tumors

2579

Background: This three-center phase I study evaluated the PARP1/2 inhibitor olaparib (O) in combination with carboplatin (C), paclitaxel (Pa) or both (CPa) in patients (pts) with advanced solid tumors refractory to standard therapies (NCT00516724). Methods: This ongoing study consists of multiple parts (P) in which escalating doses of O capsule and tablet formulations were studied. Capsule formulation data are presented; continuous O with C (P1; 21 day cycle), CPa (P2a; 21 day cycle) and weekly Pa (P2b; 28 day cycle) or intermittent O with CPa (P3; 21 day cycle). Primary and secondary objectives were safety/tolerability and antitumor activity (RECIST), respectively. Results: This analysis (non validated data) included 87 enrolled pts (P1 [n=25] P2a [n=20] P2b [n=12] and P3 [n=30]). Most common tumor types were breast (26%), melanoma (10%) and ovarian (7%). 12 pts had known gBRCA1/2 mutations. A tolerable continuous dosing schedule of O with CPa was not determined. Most common AEs (all grades) were myelosuppression (71%) notably neutropenia (54%) and thrombocytopenia (26%), and fatigue (77%). Excessive treatment cycle delays due to hematologic toxicity occurred with continuous O combined with standard doses of C or CPa. Two doses were identified as tolerable: continuous O 100 mg bd with weekly Pa 80 mg/m2 and intermittent O 200 mg bd (d1–10) with CPa AUC4/175 mg/m2 q 3 weeks. 14/87 pts (16%) had an objective response (complete response [CR] 5%; partial response [PR] 11%); 28% had stable disease for ≥4 months. Activity appeared greater in pts with BRCA1/2 mutations (CR 17%; PR 33%). Conclusions: Continuous O in combination with CPa exacerbated hematologic toxicities leading to schedule delays. Tolerability improved with intermittent O. Antitumor activity was highest in pts with a BRCA1/2 mutation. This study identified two tolerable O capsule treatment schedules for further development. Clinical trial information: NCT00516724. [Table: see text]

Abstract 302: Characterization of effects of M402 on EMT in pancreatic ductal adenocarcinoma

Background: Pancreatic ductal adenocarcinoma (PDA) is an almost uniformly lethal disease. The current treatment for resectable disease consists of surgery and adjuvant gemcitabine therapy. However, for more than 80 percent of the patients with PDA surgery is not an option. For these patients palliative chemotherapy using gemcitabine, or most recently FOLFIRINOX, is considered standard of care. Even with palliative chemotherapy the median overall survival for patients with metastatic PDA is dismal and improved therapeutic strategies are a clear unmet medical need. Heparins may be of interest for the treatment of PDA. They play an important role in tumor progression and metastasis by binding at heparin binding domains, thereby preventing growth factor gradients created along proteoglycan heparan sulfates and thus disrupting signaling. We used a novel heparan sulfate mimetic, M402, which binds to multiple growth factors, adhesion molecules, and chemokines. We previously showed that M402 decreases both epithelial-to-mesynchymal transition and chemotherapy resistance in PDA. Here we further evaluated the underlying mechanisms of M402 in EMT.

Results: We studied the effects of M402 on PDA using a genetically engineered mouse model (GEMM) for PDA (LSL-KRASG12D/+; Trp53 LSL-R172H/flox; pdx-CRE), which recapitulates human PDA. Combination therapy of M402 with gemcitabine significantly prolonged the average survival of the mice when compared to mice treated with gemcitabine monotherapy (87 days versus 78 days) and significantly reduced metastasis and local invasion into the small intestine. These data suggest an effect of M402 on invasiveness and EMT. Gemcitabine treatment increased EMT as determined by staining for E-cadherin and Fsp1 double positive cells. In contrast, M402 treatment resulted in a decrease in E-cadherin and Fsp1 double positive cells in pancreatic tumors. We next sought to determine whether M402 affects cancer cells or stromal cells. In vitro experiments show that cell lines derived from our model respond to M402 by decreasing their invasive behavior in 3D culture and scratch assays. Moreover, we found that M402 augments the gemcitabine effect in vitro. These data suggest that M402 affects both EMT and gemcitabine response. Further identification by whole transcriptome microarray analysis of treated tumors hints towards a role of M402 in affecting multiple signaling pathways involved in the regulation of EMT. These data will undoubtedly lead to better insight into the mechanism of action of M402 and will increase our understanding of the pathways PDA cells use to evade the effects of chemotherapy. M402 is currently being investigated in a phase 1/2 M402 gemcitabine combination study to assess if these findings can be translated into a clinical benefit in pancreatic cancer patients.

Conclusion: These data suggest that M402 reduces acquired chemotherapy resistance in a GEMM for PDA by decreasing EMT.

Citation Format: Ilse Oosterom, Birgit C. Schultes, Chia Lin Chu, Zoya Galcheva-Gargova, Elma Kurtagic, He Zhou, Jay Duffner, Emile E. Voest, David A. Tuveson, Martijn Lolkema. Characterization of effects of M402 on EMT in pancreatic ductal adenocarcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 302. doi:10.1158/1538-7445.AM2013-302

Does Radiofrequency Ablation Add to Chemotherapy for Unresectable Liver Metastases?

In patients with unresectable colorectal liver metastases (CRLM), radiofrequency ablation (RFA) might be a good alternative, whenever possible. In contrast to systemic therapy, the aim of RFA is to achieve complete local tumor control in an attempt to provide long-term survival. In this article we discuss the available evidence regarding the treatment of patients with unresectable CRLM, focusing on RFA in conjunction with modern systemic therapies. We observed that the available evidence in the existing literature is limited, and often consists of level 2 and 3 evidence, thereby hampering any firm conclusions. Nonetheless, RFA seems superior to chemotherapy alone in patients with liver-only disease amenable for RFA. However, the combination of RFA and chemotherapy has been demonstrated to be feasible and safe, lending support to the concept of RFA followed by chemotherapy, in order to reduce local recurrence rates and prolong survival.

Abstract LB-43: M402, a novel heparin sulphate mimetic, synergizes with gemcitabine to improve survival and reduce metastasis and epithelial-to-mesenchymal transition (EMT) in a genetically engineered mouse model for pancreatic cancer

Introduction: Heparan sulphate proteoglycans (HSPGs) play a central role in tumor progression and metastasis by presenting and modulating growth factors, cytokines, and other soluble factors. A novel heparin sulphate mimetic (M402), engineered from heparin to have low anti-coagulant activity, has shown promising anti-tumor efficacy in several pre-clinical tumor models. This study was designed to probe the efficacy and mechanism of action of M402 in a genetically engineered mouse (GEM) model for pancreatic cancer.

Methods: Mice that spontaneously develop pancreatic cancer (LSL-KRASG12D/+; Trp53 LSL-R172H/flox; pdx-CRE) were treated with twice weekly i.p. doses of saline or gemcitabine (50 mg/kg) starting at Day 30, or with saline or M402 (40 mg/kg/day) administered by a subcutaneous osmotic minipump from Day 30-90, or with a combination of gemcitabine plus M402.

Results: Treatment with M402 alone did not prolong survival and gemcitabine alone showed only a modest improvement in survival; however the combination of M402 and gemcitabine significantly improved survival. Moreover, mice treated with the combination of M402 and gemcitabine showed a substantially lower incidence of metastasis. RT-qPCR analysis revealed that M402 treated mice had significantly lower levels of TGF-alpha mRNA than the saline control group, which is corroborated by a corresponding decrease in tumor cell proliferation. Immunohistochemical analysis revealed that M402 treated mice developed reduced areas of epithelial-to-mesenchymal transition (EMT), as defined by negative staining for E-Cadherin, strongly positive staining for vimentin and positive nuclear staining for SNAIL. As there is a direct link between EGFR activation and the nuclear localisation of SNAIL we propose that M402 affects gemcitabine sensitivity and metastasis formation by reducing the expression of TGF-alpha.

Discussion: M402 increased the anti-tumor efficacy of gemcitabine in a GEM model for pancreatic cancer resulting in increased survival and, interestingly, decreased incidence of metastasis. One potential mechanism is that the observed reduction in EMT may be due to the reduced expression of TGF-alpha, a cognate ligand for EGFR. These data suggest that the EGFR pathway is active in KRAS mutant tumors. Overall, these results provide a rationale for investigating the clinical use of M402 in combination with gemcitabine in the treatment of human pancreatic cancer.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-43.

Abstract LB-374: The Hh inhibitor IPI-926 enhances tumor perfusion and nab-paclitaxel activity in a pancreatic xenograft model

Malignant activation of the Hedgehog (Hh) pathway is associated with multiple tumor types. In certain cancers, such as pancreatic, a paracrine role for the Hh ligand has been described, wherein cancer cells produce Hh ligand that activates the Hh pathway in the surrounding stroma. Consistent with this model, IPI-926, a potent and selective Smoothened (Smo) inhibitor, blocks Hh signaling in the mouse stroma -but not in the cancer cells- of several pancreatic xenograft models. We recently published (Olive, Science 2009) that IPI-926 increases vascular perfusion and enhances gemcitabine drug delivery to tumors in a genetically engineered mouse model of pancreatic cancer (KPC) leading to an increase in overall survival. To determine if similar effects could be observed in xenograft models of human pancreatic cancer, experiments were designed to study the combination of IPI-926 with nab-paclitaxel, an agent that has recently demonstrated anti-tumor activity in pancreatic cancer (Van Hoff, ASCO 2009). While IPI-926 had no single agent activity in the L3.6pl human pancreatic xenograft model, it enhanced the activity of nab-paclitaxel from 61% tumor growth inhibition (nab-paclitaxel alone) to 83% tumor growth inhibition (nab-paclitaxel plus IPI-926, p=0.0048). Tumor IHC analysis of phosphohistone 3 showed a higher frequency of cells arrested at the late G2/M phase in the IPI-926 plus nab-paclitaxel group versus nab-paclitaxel alone (p=0.02). One possible explanation for the synergistic effect of a combination of IPI-926 and nab-paclitaxel is that IPI-926 affects the mouse stroma and increases tumor perfusion and nab-paclitaxel accessibility to the tumor. Tumor perfusion was directly measured in IPI-926 treated and untreated animals using contrast enhanced ultrasound. In tumor bearing animals treated with IPI-926 for 7 days, the ultrasound data showed greater tumor perfusion with IPI-926. On average, the peak time for contrast agent levels decreased from 11.0 seconds to 4.75 seconds in the vehicle versus IPI-926 treated animals, respectively, (p=0.0321).

These data suggest that the mechanism of synergy between IPI-926 and nab-paclitaxel is likely enhanced drug delivery to the tumor through the effect of IPI-926 on the stroma. Studies are ongoing to measure nab-paclitaxel and paclitaxel levels in IPI-926 treated and untreated tumors, and to investigate these findings with the KPC in situ mouse model of pancreatic cancer. These preclinical data provide a strong rationale for evaluating the Hh inhibitor IPI-926 not only with the current standard of care, gemcitabine, but with emerging new potential therapies like nab-paclitaxel in pancreatic cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-374.

Epithelial cell-specific laminin 5 is required for survival of early thymocytes

The gene LamC2 encoding the gamma2 chain of laminin 5, an epithelial cell-specific extracellular matrix protein, was identified in a PCR-based subtracted cDNA library from mouse thymic stromal cells. The mRNA existed in two alternative forms (5.1 and 2.4 kb). The full-length message was highly expressed in SCID thymus and in a nurse cell line, but not in other thymic epithelial cell lines, while the short form was more widely expressed. In situ hybridization and immunohistochemical staining revealed laminin 5 expression mostly in the subcapsular region of the adult thymus. Addition to fetal thymic organ cultures of a cell adhesion-blocking mAb to the alpha3 chain of laminin 5 interrupted T cell development. There was a 40% reduction in the total yield of thymocytes, and the most profound decrease (75-90%) was seen in the CD25+CD44+ and CD25+CD44-subsets of the CD4-CD8- double negative fraction. Most of the surviving double negative thymocytes expressed Sca-1, and there were significant increases in the number of cells with CD69 expression and in the fraction of annexin V-stained cells. None of these changes were observed with a nonblocking anti-laminin alpha3 chain mAb. These results suggest that the interaction between double negative thymoctyes and laminin 5 made by subcapsular epithelial cells is required for the survival and differentiation of mouse thymocytes.

Natural adjuvants: endogenous activators of dendritic cells

Dendritic cells, the most potent antigen-presenting cells, need to be activated before they can function to initiate an immune response. We report here that, in the absence of any foreign substances, dendritic cells can be activated by endogenous signals received from cells that are stressed, virally infected or killed necrotically, but not by healthy cells or those dying apoptotically. Injected in vivo with an antigen, the endogenous activating substances can function as natural adjuvants to stimulate a primary immune response, and they may represent the natural initiators of transplant rejection, spontaneous tumor rejection, and some forms of autoimmunity.