Abstract 4336: Integrative genomic and transcriptomic analysis of leiomyosarcoma

Leiomyosarcomas (LMS) are malignant tumors of smooth-muscle origin that occur across age groups. The mechanisms underlying LMS development, including clinically actionable genetic vulnerabilities, are largely unknown, and few therapeutic options exist for LMS patients. To detect somatic mutations, copy number alterations, and structural rearrangements, we performed whole-exome and transcriptome sequencing of 49 and 37 LMS tumors, respectively, and performed integrative analysis. Recurrence analysis identified TP53, RB1, and ATRX as significantly mutated genes and various other cancer-associated genes mutated at low frequency, indicating substantial mutational heterogeneity. Copy number analysis revealed widespread chromosomal gains and losses and highly rearranged genomes in all tumors. Additionally, chromothripsis and whole-genome duplication were detected in 35% and 51% of cases, respectively. Principle component analysis and unsupervised hierarchical clustering of transcriptome data revealed three distinct subgroups of patients. Furthermore, we detected multiple non-recurrent fusion transcripts resulting from chromosomal rearrangements, many of which were predicted to result in loss of TP53 and RB1 function. In-depth analysis of these loci revealed protein-damaging microdeletions, intragenic or distal inversions, and exon skipping events as additional, previously unrecognized mechanisms of TP53 and RB1 disruption. Integration of whole-exome and transcriptome data demonstrated biallelic disruption of TP53 and RB1 in 92% and 94% of cases, respectively, and tumors with wildtype RB1 displayed loss of CDKN2A expression, overexpression of CCND1, or mutation of MAX resulting in CDK4 and CCND2 overexpression as alternative mechanisms of RB1 suppression. We also detected alternative lengthening of telomeres (ALT) in 78% of cases, and identified recurrent alterations in telomere maintenance genes such as ATRX, RBL2, and SP100, providing novel insight into the genetic basis of this mechanism. Finally, most tumors displayed hallmarks of “BRCAness”, including alterations in homologous recombination DNA repair genes and enrichment of specific mutational signatures, and cultured LMS cells were sensitive towards olaparib and cisplatin. This comprehensive genomic and transcriptomic analysis has unveiled that LMS is characterized by mutational heterogeneity, genomic instability, near-universal inactivation of TP53 and RB1, and frequent whole-genome duplication. Furthermore, we have established that most LMS tumors rely on ALT to escape replicative senescence, and identified recurrent alterations in a broad spectrum of telomere maintenance genes. Finally, our findings uncover “BRCAness” as potentially actionable feature of LMS tumors, and provide a rich resource for guiding future investigations into the mechanisms underlying LMS development and the design of novel therapeutic strategies.

Citation Format: Priya Chudasama, Sadaf Mughal, Mathijs Sanders, Daniel Hübschmann, Inn Chung, Aurélie Ernst, Bernd Kasper, Hans-Georg Kopp, Sebastian Bauer, Karsten Rippe, Benedikt Brors, Marcus Renner, Peter Hohenberger, Claudia Scholl, Stefan Fröhling. Integrative genomic and transcriptomic analysis of leiomyosarcoma [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 4336.

Impact of surgery in patients with metastatic soft tissue sarcoma: A monocentric retrospective analysis

Background and Objectives

The role of local surgical procedures in patients with metastatic soft tissue sarcoma is still undefined. Few retrospective studies have reported survival benefits for patients with pulmonary metastases after complete surgical resection. Treatment decisions are therefore mainly based on personal experiences rather than on reproducible knowledge.

Method

A total of 237 patients with metastatic sarcoma, treated between 1982 and 2015 at the University Hospital Tuebingen, Germany, were eligible for inclusion. Out of the 237 screened patients, 102 patients underwent at least one metastasectomy. Overall survival was defined as the primary endpoint in this study. For association of non‐linear relationship to the endpoint, significant prognostic factors were included into a recursive partitioning model. A subgroup analysis for long‐term survivors was also performed.

Results

The median overall survival was 64 months. The 3‐, 5‐, 10‐, and 20‐years overall survival rates were 70.7%, 50.3%, 24.7%, and 14.8%, respectively. The number of resections and the progression‐free intervals were independent prognostic factors in three statistical models.

Conclusion

Repeated resections of metastases from different localizations are a strong predictor for prolonged survival. We suggest that the progression‐free interval after metastasectomy should be considered as a predictive factor for benefit from further surgery.

The novel deubiquitinase inhibitor b-AP15 induces direct and NK cell-mediated antitumor effects in human mantle cell lymphoma

The first therapeutic proteasome inhibitor bortezomib has clinical efficacy in mantle cell lymphoma (MCL) which resulted in its incorporation in treatment algorithms for this disease. Impairment of proteasomal function by bortezomib is mediated via inhibition of the 20S core particle. However, proteasome function can also be modified by targeting upstream components of the ubiquitin-proteasome system. Recently, b-AP15 has been identified as a small molecule achieving proteasome inhibition by targeting the deubiquitinase (DUB) activity of the 19S regulatory subunit and was found to inhibit cancer cell growth in preclinical analyses. In the present study, both direct antitumor effects and the possibility to induce natural killer group 2 member D ligands (NKG2DL) to reinforce NK cell immunity with b-AP15 were investigated to provide a rational basis for clinical evaluation of this novel DUB inhibitor in MCL. Treatment with b-AP15 resulted in reduced viability as well as induction of apoptosis in a time- and dose-dependent manner, which could be attributed to caspase activation in MCL cells. In addition, treatment with b-AP15 differentially induced NKG2DL expression and subsequent NK cell lysis of MCL cells. These results indicate that the DUB inhibitor b-AP15 displays substantial antitumor activity in human MCL and suggest that b-AP15 might be a novel therapeutic option in the treatment of MCL that warrants clinical investigation.

Mapping the HLA Ligandome of Colorectal Cancer Reveals an Imprint of Malignant Cell Transformation

Immune cell infiltrates have proven highly relevant for colorectal carcinoma prognosis, making colorectal cancer a promising candidate for immunotherapy. Because tumors interact with the immune system via HLA-presented peptide ligands, exact knowledge of the peptidome constitution is fundamental for understanding this relationship. Here, we comprehensively describe the naturally presented HLA ligandome of colorectal carcinoma and corresponding nonmalignant colon (NMC) tissue. Mass spectrometry identified 35,367 and 28,132 HLA class I ligands on colorectal carcinoma and NMC, attributable to 7,684 and 6,312 distinct source proteins, respectively. Cancer-exclusive peptides were assessed on source protein level using the Kyoto Encyclopedia of Genes and Genomes (KEGG) and protein analysis through evolutionary relationships (PANTHER), revealing pathognomonic colorectal carcinoma-associated pathways, including Wnt, TGFβ, PI3K, p53, and RTK-RAS. Relative quantitation of peptide presentation on paired colorectal carcinoma and NMC tissue further identified source proteins from cancer- and infection-associated pathways to be overrepresented merely within the colorectal carcinoma ligandome. From the pool of tumor-exclusive peptides, a selected HLA-ligand subset was assessed for immunogenicity, with the majority exhibiting an existing T-cell repertoire. Overall, these data show that the HLA ligandome reflects cancer-associated pathways implicated in colorectal carcinoma oncogenesis, suggesting that alterations in tumor cell metabolism could result in cancer-specific, albeit not mutation-derived, tumor antigens. Hence, a defined pool of unique tumor peptides, attributable to complex cellular alterations that are exclusive to malignant cells, might comprise promising candidates for immunotherapeutic applications.Significance: Cancer-associated pathways are reflected in the antigenic landscape of colorectal cancer, suggesting that tumor-specific antigens do not necessarily have to be mutation-derived but may also originate from other alterations in cancer cells. Cancer Res; 78(16); 4627-41. ©2018 AACR.

The BCR-ABL inhibitor nilotinib influences phenotype and function of monocyte-derived human dendritic cells

In chronic myeloid leukemia (CML), the translocation t(9;22) results in the fusion protein BCR-ABL (breakpoint cluster region-abelson murine leukemia), a tyrosine kinase mediating oncogenic signaling which is successfully targeted by treatment with BCR-ABL inhibitors like imatinib. However, BCR-ABL inhibitors may also affect antitumor immunity. For instance, it was reported that imatinib impairs the function of dendritic cells (DCs) that play a central role in initiating and sustaining T cell responses. Meanwhile, second generation BCR-ABL inhibitors like nilotinib, which inhibits BCR-ABL with enhanced potency have become standard of treatment, at least in patients with BCR-ABL kinase domain mutations. In this study we analyzed the influence of therapeutic concentrations of nilotinib on human monocyte-derived DCs and compared its effects to imatinib. We found that both tyrosine kinase inhibitors (TKI) comparably and significantly impaired differentiation of monocytes to DCs as revealed by curtated downregulation of CD14 and reduced upregulation of CD1a and CD83. This was only partially restored after withdrawal of the TKI. Moreover, both TKI significantly reduced activation-induced IL-12p70 and C-C motif chemokine ligand (CCL) 3 secretion, while divergent TKI effects for CCL2 and CCL5 were observed. In contrast, only nilotinib significantly impaired the migratory capacity of DCs and their capacity to induce T-cell immune responses in MLRs. Our results indicate that imatinib and nilotinib may differ significantly with regard to their influence on antitumor immunity. Thus, for future combinatory approaches and particularly stop studies in CML treatment, choice of the most suitable BCR-ABL inhibitor requires careful consideration.

Enhanced eryptosis contributes to anemia in lung cancer patients

Objectives

Anemia is a common complication of malignancy, which could result from either compromised erythropoiesis or decreased lifespan of circulating erythrocytes. Premature suicidal erythrocyte death, characterized by cell shrinkage and phosphatidylserine (PS) externalization, decreases erythrocyte lifespan and could thus cause anemia. Here, we explored whether accelerated eryptosis participates in the pathophysiology of anemia associated with lung cancer (LC) and its treatment.

Methods

Erythrocytes were drawn from healthy volunteers and LC patients with and without cytostatic treatment. PS exposure (annexin V-binding), cell volume (forward scatter), cytosolic Ca²⁺ (Fluo3 fluorescence), reactive oxygen species (ROS) production (DCFDA fluorescence) and ceramide formation (anti-ceramide antibody) were determined by flow cytometry.

Results

Hemoglobin concentration and hematocrit were significantly lower in LC patients as compared to healthy controls, even though reticulocyte number was higher in LC (3.0±0.6%) than in controls (1.4±0.2%). The percentage of PS-exposing erythrocytes was significantly higher in LC patients with (1.4±0.1%) and without (1.2±0.3%) cytostatic treatment as compared to healthy controls (0.6±0.1%). Erythrocyte ROS production and ceramide abundance, but not Fluo3 fluorescence, were significantly higher in freshly drawn erythrocytes from LC patients than in freshly drawn erythrocytes from healthy controls. PS exposure of erythrocytes drawn from healthy volunteers was significantly more pronounced following incubation in plasma from LC patients than following incubation in plasma from healthy controls.

Conclusion

Anemia in LC patients with and without cytostatic treatment is paralleled by increased eryptosis, which is triggered, at least in part, by increased oxidative stress and ceramide formation.

Platelet-mediated shedding of NKG2D ligands impairs NK cell immune-surveillance of tumor cells

Platelets promote metastasis, among others by coating cancer cells traveling through the blood, which results in protection from NK cell immune-surveillance. The underlying mechanisms, however, remain to be fully elucidated. Here we report that platelet-coating reduces surface expression of NKG2D ligands, in particular MICA and MICB, on tumor cells, which was mirrored by enhanced release of their soluble ectodomains. Similar results were obtained upon exposure of tumor cells to platelet-releasate and can be attributed to the sheddases ADAM10 and ADAM17 that are detectable on the platelet surface and in releasate following activation and at higher levels on platelets of patients with metastasized lung cancer compared with healthy controls. Platelet-mediated NKG2DL-shedding in turn resulted in impaired "induced self" recognition by NK cells as revealed by diminished NKG2D-dependent lysis of tumor cells. Our results indicate that platelet-mediated NKG2DL-shedding may be involved in immune-evasion of (metastasizing) tumor cells from NK cell reactivity.

NFAT2 is a critical regulator of the anergic phenotype in chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is a clonal disorder of mature B cells. Most patients are characterised by an indolent disease course and an anergic phenotype of their leukaemia cells, which refers to a state of unresponsiveness to B cell receptor stimulation. Up to 10% of CLL patients transform from an indolent subtype to an aggressive form of B cell lymphoma over time (Richter´s syndrome) and show a significantly worse treatment outcome. Here we show that B cell-specific ablation of Nfat2 leads to the loss of the anergic phenotype culminating in a significantly compromised life expectancy and transformation to aggressive disease. We further define a gene expression signature of anergic CLL cells consisting of several NFAT2-dependent genes including Cbl-b, Grail, Egr2 and Lck. In summary, this study identifies NFAT2 as a crucial regulator of the anergic phenotype in CLL.NFAT2 is a transcription factor that has been linked with chronic lymphocytic leukaemia (CLL), but its functions in CLL manifestation are still unclear. Here the authors show, by analysing mouse CLL models and characterising biopsies from CLL patients, that NFAT2 is an important regulator for the anergic phenotype of CLL.

Radiotherapy and hyperthermia with curative intent in recurrent high risk soft tissue sarcomas

PURPOSE

Radiotherapy before or after resection is one of the pillars of treatment for localised high risk soft tissue sarcomas. Treatment intensification has been described with concurrent chemotherapy and hyperthermia. The aim of this study is to assess local control after multimodal treatment, focussing on the treatment of local recurrences after surgery only.

PATIENTS AND METHODS

Of 42 patients treated in a prospective protocol with radiotherapy and hyperthermia, nine were treated for isolated local recurrences without metastatic spread. Most patients were treated with trimodal therapy including chemotherapy with ifosfamide and underwent resection whenever possible. Median follow-up was 1.4 years.

RESULTS

The treatment was well tolerated. Estimated disease free survival, distant metastases free survival and local control for the whole cohort after 1.5 years were 66, 73 and 88%, respectively. Neoadjuvant vs. adjuvant treatment influenced local control with a trend to statistical significance. Resection status did not influence local control. The cohort of patients treated for local recurrence after surgery alone had a significantly impaired local control compared to multimodal treatment at primary diagnosis (100 vs. 52%, p < 0.001).

CONCLUSIONS

With multimodal therapy including radiotherapy and hyperthermia local tumour control is achievable even in locally recurrent tumours. The clear-cut difference of the treatment of local recurrence in contrast to primary diagnosis might either reflect difficulties in diagnosis and treatment of local recurrences or biological aggressiveness of recurrent tumours. However, we recommend to consider multimodal treatment at primary diagnosis of high risk soft tissue sarcomas.

Perioperative chemotherapy with docetaxel, oxaliplatin, and fluorouracil/leucovorin (FLOT) versus epirubicin, cisplatin, and fluorouracil or capecitabine (ECF/ECX) for resectable gastric or gastroesophageal junction (GEJ) adenocarcinoma (FLOT4-AIO): A multicenter, randomized phase 3 trial

4004

Background: The MAGIC trial established perioperative (periop) epirubicin, cisplatin, and 5-FU (ECF) as a standard treatment for patients (pts) with operable esophagogastric cancer, but survival continues to remain poor. FLOT4 (NCT01216644) is a multicenter, randomized, investigator-initiated, phase 3 trial. It compares the docetaxel-based triplet FLOT with the anthracycline-based triplet ECF/ECX as a periop treatment for pts with resectable gastric or GEJ adenocarcinoma. Methods: Eligible pts of stage ≥cT2 and/or cN+ were randomized to either 3 preoperative and 3 post-operative 3-week cycles of ECF/ECX (epirubicin 50 mg/m2, cisplatin 60 mg/m², both d1, and 5-FU 200 mg/m² as continuous infusion or capecitabine 1250 mg/m2 orally d1-21) or 4 pre-operative and 4 post-operative 2-week cycles of FLOT (docetaxel 50 mg/m2, oxaliplatin 85 mg/m², leucovorin 200 mg/m², and 5-FU 2600 mg/m² as 24-hour infusion, all d1). The primary endpoint was overall survival (OS; 80% power; HR of 0.76; 2-sided log-rank test at 5% type I error). Results: Between Aug 2010 and Feb 2015, 716 pts (360 ECF/ECX; 356 FLOT) were randomly allocated. Baseline characteristics were similar between arms (overall, male 74%; median age 62; cT3/T4 81%; cN+ 80%; GEJ 56%). 91% and 37% of pts with ECF/ECX and 90% and 50% with FLOT completed planned pre-operative and post-operative cycles, respectively. Median follow-up was 43 mon. 369 pts died (203 ECF/ECX; 166 FLOT). FLOT improved OS (mOS, 35 mon with ECX/ECF vs. 50 mon with FLOT; HR 0.77 [0.63 - 0.94]; p = 0.012). 3y OS rate was 48% with ECF/ECX and 57% with FLOT. FLOT also improved PFS (mPFS, 18 mon with ECX/ECF vs. 30 mon with FLOT; HR 0.75 [0.62 - 0.91]; p = 0.004). Periop complications were 50% with ECF/ECX and 51% with FLOT. 30- and 90-day mortality was 3% and 8% with ECF/ECX and 2% and 5% with FLOT. There was more G3/4 nausea and vomiting with ECF/ECX and more G3/4 neutropenia with FLOT. Conclusion: Periop FLOT improved outcome in patients with resectable gastric and GEJ cancer compared to periop ECF/ECX. Clinical trial information: NCT01216644.

A randomized, double-blind, multi-center phase III study evaluating paclitaxel with and without RAD001 in patients with gastric or esophagogastric junction carcinoma who have progressed after therapy with a fluoropyrimidine/platinum-containing regimen (RADPAC)

4027

Background: There is a need for effective treatments in the second- or further line setting in advanced gastric cancer, especially for new agents. In the current trial we evaluated paclitaxel with RAD001 (everolimus) in patients with gastric carcinoma who have progressed after therapy with a fluoropyrimidine/platinum-containing regimen. Methods: This is a randomized, double-blind, multi-center phase III study. Patients with gastric carcinoma or adenocarcinoma of the esophagogastric junction (EGJ) who have progressed after treatment with a fluoropyrimidine/platinum-containing regimen were randomly assigned to receive Paclitaxel (80 mg/m2) on day 1, 8 and 15 plus placebo (arm A) or RAD001 (10mg daily, arm B) d1-d28, repeated every 28 days as 2nd, 3rd or 4th line therapy. Primary end point was overall survival (OS), secondary endpoints were best overall response, disease control rate, progression free survival (PFS) and toxicity. Results: 300 patients (median age: 62 years; median lines prior therapy: 2; 47.7% of patients had prior taxane therapy) were randomly assigned (Arm A, 150, Arm B, 150). In the intention to treat population, there was no significant difference in median PFS (placebo, 2.07 vs. RAD001, 2.2 months, HR 0.88, p = 0.3) or median OS (placebo, 5.0 vs. RAD001, 6.1 months, HR 0.93, p = 0.54). For patients with prior taxane use, RAD001 improved PFS (placebo 1.8 vs. RAD001, 2.7 months, HR 0.69, p = 0.03) and OS (placebo 3.9 vs. RAD001, 5.8 months, HR 0.73, p = 0.07). Combination of paclitaxel and RAD001 was tolerable, but the RAD001 arm was associated with significantly more grade 3-5 mucositis (13.3% vs. 0.7%; p < 0.001). Conclusions: The addition of RAD001 to paclitaxel/RAD001 did not improve outcomes in pretreated metastatic gastric/EGJ cancer. Of note, activity was seen in the taxane pretreated group. Additional biomarker studies are planned to look for subgroups that may have a benefit. Clinical trial information: 2009-018092-14.

A randomized, double-blind, multicenter phase III study evaluating paclitaxel with and without RAD001 in patients with gastric cancer who have progressed after therapy with a fluoropyrimidine/platinum-containing regimen (RADPAC)

4

Background: There is a need for effective treatments in the second- or further line setting in advanced gastric cancer, especially for new agents. In the current trial we evaluated paclitaxel with RAD001 (everolimus) in patients with gastric carcinoma who have progressed after therapy with a fluoropyrimidine/platinum-containing regimen. Methods: This is a randomized, double-blind, multi-center phase III study. Patients with gastric carcinoma or adenocarcinoma of the esophagogastric junction which has progressed after treatment with a fluoropyrimidine/platinum-containing regimen were randomly assigned to receive Paclitaxel (80 mg/m2) on day 1, 8 and 15 plus placebo (arm A) or RAD001 (10mg daily, arm B) d1-d28, repeated every 28 days as 2nd, 3rd or 4thline therapy. Primary end point was overall survival (OS), secondary endpoints were best overall response, disease control rate, progression free survival (PFS) and toxicity. Results: 300 patients (median age: 62 years; median lines prior therapy: 2) were randomly assigned (Arm A, 150, Arm B, 150). Response rate (complete and partial response) was 8.0% (95%CI: 4.2%-13.6%) in the paclitaxel/RAD001 arm and 7.3% (95% CI: 3.7%-12.7%) in the paclitaxel/placebo arm (p = 0.4).There was no significant difference in median PFS (placebo, 2.07 vs. RAD001, 2.2 months, HR 0.88, p = 0.3) and median OS (placebo, 5.1 vs. RAD001, 6.1 months, HR 0.92, p = 0.48). Combination of paclitaxel and RAD001 was tolerable, but the placebo arm was associated with significantly less (any grade) mucositis (15.8% vs. 37.2%), fever (10.3% vs 20.7%), leukopenia (11.6% vs. 21.4%), neutropenia (13.0% vs. 27.6%) and thrombocytopenia (2.1% vs 14.5%). Conclusions: The addition of RAD001 to paclitaxel/RAD001 did not significantly improve outcomes in pretreated metastatic gastric or esophagogastric junction adenocarcinoma. Additional biomarker studies are planned to look for subgroups that may have a benefit. Clinical trial information: NCT01248403.

Targeted Treatment of Esophagogastric Cancer

Adenocarcinoma of the esophagogastric junction (EGJ) and stomach remains one of the most common causes of cancer-related death worldwide. Although there is increasing data on the mutational landscape of esophagogastric cancer, phase III trials often yield negative results, and there is a paucity of approved targeted agents. For the time being, the subset of patients carrying HER2-positive metastatic tumors can receive trastuzumab in addition to chemotherapy. Furthermore, ramucirumab has been found to be active both as a single agent and in combination with paclitaxel. Herein, we give an overview of currently approved targeted treatments for locally advanced/resectable as well as unresectable/metastatic EGJ/gastric adenocarcinoma, summarizing the underlying clinical studies. Moreover, further potential targets still under investigation are presented.

Efficacy and safety of Dexrazoxane (DRZ) in sarcoma patients receiving high cumulative doses of anthracycline therapy - a retrospective study including 32 patients

BACKGROUND

Anthracyclines, as the most effective therapy, are the cornerstone of advanced stage sarcoma treatment. However, anthracyclines can also contribute to myocardial dysfunction and congestive heart failure, ultimately limiting the therapeutic potential of the drug. Coadministration of Dexrazoxane has been shown to effectively reduce cardiotoxicity, however primarily in patients suffering in diseases other than sarcoma.

METHODS

The aim of this retrospective analysis was to evaluate safety and efficacy of chemotherapy with high cumulative doses of anthracyclines in combination with Dexrazoxane. The medical charts of 32 patients treated in four institutions were analyzed. Reasons for coadministration were rechallenge, reaching the cumulative anthracycline dose and preexisting heart failure.

RESULTS

The median age was 54 years [18-68 years]. The median cumulative anthracycline dose before adding DRZ was 450 mg/m(2) and after administration of last anthracycline containing therapy 750 mg/m(2). Either during treatment or follow up, 2/27 patients (7 %) without preexisting major cardiac findings developed anthracycline-induced cardiotoxicity. The median overall survival (OS) from start of the first anthracycline containing chemotherapy was 46 months and 17 months from the initial coadministration of DRZ. At rechallenge, the median progression free survival (PFS) with DRZ was 7 months. In continuous therapy, the median PFS was 13 months from beginning of chemotherapy and 9 months from the addition of DRZ.

CONCLUSION

Chemotherapy with high cumulative doses of anthracyclines in addition with DRZ demonstrated a remarkable OS in these advanced disease patients. Cardiac side-effects due to high cumulative doses of anthracyclines requiring discontinuation of anthracycline treatment were rare. A PFS of 9 months from the beginning of the coadministration of DRZ indicates that continuing anthracycline therapy beyond established cumulative doses is a promising therapeutic option.

Choroidal metastases from thymic carcinoma during pregnancy: Case Report

BACKGROUND

Rare sites of metastases, atypical symptoms and paraneoplastic syndromes are often neglected or misinterpreted, especially when they represent early symptoms of an underlying malignant disease. Hence, an interdisciplinary approach to these patients is essential to avoid tumor progression and metastatic spread in order to provide curative treatment options to the patients. We here report the case of a young woman presenting with visual loss which led to diagnosis of a thymic carcinoma.

CASE PRESENTATION

A 28-year old white woman presented with subacute loss of vision in the last trimester of her first pregnancy which was first interpreted as an exacerbation of a pre-existing dermatomyositis and treated with steroids. After failure of steroid therapy choroidal metastases from an undifferentiated thymic carcinoma were diagnosed. This also shed a new light on the dermatomyositis the patient had been suffering from for seven years possibly representing a paraneoplastic syndrome from the tumor. Despite aggressive chemotherapy, the patient died from progressive disease eight years after first onset of dermatomyositis and 14 months after initial diagnosis of the thymic carcinoma.

CONCLUSIONS

Choroidal metastases from a thymic carcinoma have never been reported before but should be included into the differential diagnosis of choroidal masses.

Abstract B61: Exploratory analyses of the randomized phase 2 IMPACT study: Patients with response to prior induction chemotherapy have improved outcome when treated with the TLR-9 agonist MGN1703

Background: The international randomized (2:1) double-blind placebo-controlled phase 2 IMPACT trial recruited patients with metastatic colorectal cancer (mCRC) and disease control after induction with 1st-line chemotherapy +/- bevacizumab. The trial aimed to assess the clinical efficacy, safety, and immunological effects of the immunomodulator MGN1703, a potent Toll-Like Receptor 9 (TLR9) agonist, given at the dose of 60 mg subcutaneously twice weekly as switch maintenance after 4.5 to 6 months of induction therapy.

Methods: After randomization of 59 patients (43 MGN1703, 16 placebo) the trial was prematurely closed. The final analysis showed superiority of MGN1703 over placebo with hazard ratios (HR) for the primary endpoint PFS on maintenance of 0.55 (p=0.041) and 0.56 (p=0.070) by local investigator assessment or independent radiological review, respectively. Some delayed and long term responses were observed, 3 still ongoing in excess of 36 months. Exploratory PFS analyses of pretreatment characteristics identified patients with objective response (HR=0.39, p=0.0051), normalized CEA (HR=0.07, p&lt;0.0001), and the presence of activated NKT-cells (CD3+/CD56+/CD69+) (HR=0.26, p=0.0017) at the end of induction chemotherapy to benefit the most from maintenance with MGN1703. Since PFS is not considered the best endpoint to assess the benefit of immunotherapies, we analyzed the impact of these factors on the secondary endpoint overall survival (OS).

Results: Despite a median follow up of 17.7 months at the time of final study analysis, the OS data were not mature with only 35% and 50% of patients in the MGN1703 arm and placebo arm with an event, respectively. The power of the following OS analyses is therefore limited and will require confirmation when a large majority of events has been observed. The HR for the whole study ITT population was 0.63 (median 22.6 vs. 15.1 months for MGN1703 vs. placebo; p=NS). The subgroup of patients who were randomized into the study after achieving a RECIST response to prior induction therapy had HR of 0.40 (median 24.5 vs. 15.1 months; p=NS). Patients randomized in the study with stable disease had instead no benefit (HR 1.57; p=NS). The HR for OS of patients with presence of activated NKT cells and normalized CEA level after induction therapy was 0.43 and 0.69, respectively. Overall these results appear in line with the evidence from PFS subgroup analyses suggesting that responders may benefit the most from switch maintenance treatment with MGN1703. Recent literature provides a rationale for such finding, as a large series showed that presence of high density of lymphocyte infiltration in CRC metastases strongly predicts responses to chemotherapy (Halama et al, Cancer Res 2011; 71:5670-5677). A good response to chemotherapy may thus be a surrogate marker for increased immunogenicity of the tumor and allow identifying patients with an immune system that may be able to control tumor progression when broadly activated by MGN1703. Based on this hypothesis, the phase 3 IMPALA study has recently started recruitment in several European countries. Patients who achieved an objective response to their 1st-line induction therapy for mCRC are randomized to either continue local standard treatment or start switch maintenance with MGN1703. CEA and activated NKT values at baseline are stratification factors and will be also assessed prospectively.

Conclusions: The exploratory PFS and OS subgroup data from the IMPACT study support the hypothesis that is possible to identify patients more likely to benefit from an immunomodulatory treatment following active induction chemotherapy. This information has been used to design the phase 3 IMPALA study currently recruiting patients.

Citation Format: Werner Scheithauer, Jorge Riera-Knorrenschild, Hans-Georg Kopp, Frank Mayer, Hendrik Kroening, Dieter Nitsche, Jan Kuhlmann, Reinhard Ziebermayr, Johannes Andel, Dirk Arnold, Alfredo Zurlo, Burghardt Wittig, Hans-Joachim Schmoll. Exploratory analyses of the randomized phase 2 IMPACT study: Patients with response to prior induction chemotherapy have improved outcome when treated with the TLR-9 agonist MGN1703. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr B61.