Joël R. Gsponer

Preexisting BCG-Specific T Cells Improve Intravesical Immunotherapy for Bladder Cancer

Preexisting immunity to BCG improves treatment response to intravesical BCG therapy for bladder cancer in mouse models and humans. Bugs as Drugs Although still in its infancy for the treatment of many tumor types, immunotherapy has been and remains the standard of care for patients with bladder cancer. The concept behind this success is repeated instillations of bacillus Calmette-Guérin (BCG; the same bacteria used as a vaccine for Mycobacterium tuberculosis) in the bladder, inducing an immune response that fights the cancer. The clinical response rate in bladder cancer patients is 50 to 70%, higher than any other immunotherapy but still leaving room for improvement. Biot et al. provide new insight into the mechanisms behind BCG’s success in the bladder and suggest that parenteral BCG exposure may boost the success rate for bladder cancer treatment. Using a mouse model of bladder cancer, the authors show that a single instillation of BCG induced an immune response, but repetitive instillations were required for robust T cell trafficking to the bladder. Previous parenteral exposure to BCG overcame this requirement in the mice, inducing an enhanced innate immune response, accelerating T cell trafficking to the bladder, and improving the immune response to the tumor. Furthermore, bladder cancer patients who had preexisting immunity to BCG (secondary to their childhood M. tuberculosis vaccination) showed improved recurrence-free survival after standard BCG therapy relative to those patients without preexisting immunity. Thus, immunizing BCG-naïve cancer patients before therapy may provide a simple strategy that could improve therapeutic response. Therapeutic intravesical instillation of bacillus Calmette-Guérin (BCG) is effective at triggering inflammation and eliciting successful tumor immunity in patients with non–muscle invasive bladder cancer, with 50 to 70% clinical response. Therapeutic success relies on repeated instillations of live BCG administered as adjuvant therapy shortly after tumor resection; however, the precise mechanisms remain unclear. Using an experimental model, we demonstrate that after a single instillation, BCG could disseminate to bladder draining lymph nodes and prime interferon-γ–producing T cells. Nonetheless, repeated instillations with live BCG were necessary for a robust T cell infiltration into the bladder. Parenteral exposure to BCG before instillation overcame this requirement; after the first intravesical instillation, BCG triggered a more robust acute inflammatory process and accelerated T cell entry into the bladder, as compared to the standard protocol. Moreover, parenteral exposure to BCG before intravesical treatment of an orthotopic tumor markedly improved response to therapy. Indeed, patients with sustained preexisting immunity to BCG showed a significant improvement in recurrence-free survival. Together, these data suggest that monitoring patients’ response to purified protein derivative, and, in their absence, boosting BCG responses by parenteral exposure before intravesical treatment initiation, may be a safe and effective means of improving intravesical BCG-induced clinical responses.

Bacillus Calmette-Guérin Strain Differences Have an Impact on Clinical Outcome in Bladder Cancer Immunotherapy

BACKGROUND Whether the commonly used bacillus Calmette-Guérin (BCG) strains Connaught and Tice confer different treatment responses in non-muscle-invasive bladder cancer (NMIBC) is unknown. OBJECTIVES To compare clinical efficacy, immunogenicity, and genetics of BCG Connaught and Tice. DESIGN, SETTING, AND PARTICIPANTS A prospective randomized single-institution trial with treatment of 142 high-risk NMIBC patients with BCG Connaught or Tice. INTERVENTION Patients were randomized to receive six instillations of BCG Connaught or Tice. For experimental studies, BCG strains were compared in C57Bl/6 mice. Bladders and lymphoid tissues were analyzed by cytometry and the latter cultivated to detect live BCG. BCG genomic DNA was sequenced and compared with reference genomes. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Recurrence-free survival was the primary end point of the clinical study. The Kaplan-Meier estimator was used for estimating survival and time-to-event end points. Nonparametric tests served for the analysis of the in vivo results. RESULTS AND LIMITATIONS Treatment with BCG Connaught conferred significantly greater 5-yr recurrence-free survival compared with treatment with BCG Tice (p=0.0108). Comparable numbers of patients experienced BCG therapy-related side effects in each treatment group (p=0.09). In mice, BCG Connaught induced stronger T-helper cell 1-biased responses, greater priming of BCG-specific CD8(+) T cells, and more robust T-cell recruitment to the bladder than BCG Tice. Genome sequencing of the BCG strains revealed candidate genes potentially involved in the differential clinical responses. CONCLUSIONS BCG strain may have an impact on treatment outcome in NMIBC immunotherapy. PATIENT SUMMARY We compared the efficacy of two commonly used bacillus Calmette-Guérin (BCG) strains for the treatment of NMIBC and found that treatment with BCG Connaught prevented recurrences more efficiently than BCG Tice. Comparison of the immunogenicity of the two strains in mice indicated superior immunogenicity of BCG Connaught. We also identified genetic differences that may explain the differential efficacy of the Connaught and Tice BCG strains. TRIAL REGISTRATION NCT00003779.

Deep Clonal Profiling of Formalin Fixed Paraffin Embedded Clinical Samples

Formalin fixed paraffin embedded (FFPE) tissues are a vast resource of annotated clinical samples. As such, they represent highly desirable and informative materials for the application of high definition genomics for improved patient management and to advance the development of personalized therapeutics. However, a limitation of FFPE tissues is the variable quality of DNA extracted for analyses. Furthermore, admixtures of non-tumor and polyclonal neoplastic cell populations limit the number of biopsies that can be studied and make it difficult to define cancer genomes in patient samples. To exploit these valuable tissues we applied flow cytometry-based methods to isolate pure populations of tumor cell nuclei from FFPE tissues and developed a methodology compatible with oligonucleotide array CGH and whole exome sequencing analyses. These were used to profile a variety of tumors (breast, brain, bladder, ovarian and pancreas) including the genomes and exomes of matching fresh frozen and FFPE pancreatic adenocarcinoma samples.

Estrogen receptor β expression and androgen receptor phosphorylation correlate with a poor clinical outcome in hormone-naïve prostate cancer and are elevated in castration-resistant disease

Patients with advanced prostate cancer (PC) are usually treated with androgen withdrawal. While this therapy is initially effective, nearly all PCs become refractory to it. As hormone receptors play a crucial role in this process, we constructed a tissue microarray consisting of PC samples from 107 hormone-naïve (HN) and 101 castration-resistant (CR) PC patients and analyzed the androgen receptor (AR) gene copy number and the protein expression profiles of AR, Serin210-phosphorylated AR (pAR(210)), estrogen receptor (ER)β, ERα and the proliferation marker Ki67. The amplification of the AR gene was virtually restricted to CR PC and was significantly associated with increased AR protein expression (P<0.0001) and higher tumor cell proliferation (P=0.001). Strong AR expression was observed in a subgroup of HN PC patients with an adverse prognosis. In contrast, the absence of AR expression in CR PC was significantly associated with a poor overall survival. While pAR(210) was predominantly found in CR PC patients (P<0.0001), pAR(210) positivity was observed in a subgroup of HN PC patients with a poor survival (P<0.05). Epithelial ERα expression was restricted to CR PC cells (9%). ERβ protein expression was found in 38% of both HN and CR PCs, but was elevated in matched CR PC specimens. Similar to pAR(210), the presence of ERβ in HN patients was significantly associated with an adverse prognosis (P<0.005). Our results strongly suggest a major role for pAR(210) and ERβ in HN PC. The expression of these markers might be directly involved in CR tumor growth.

Early development of human lymphomas in a prostate cancer xenograft program using triple knock-out immunocompromised mice

There is an urgent need for preclinical models of prostate cancer; however, clinically relevant patient‐derived prostate cancer xenografts (PDXs) are demanding to establish.

Abstract 5386: Immunotherapy of bladder cancer using bacillus calmette guérin (BCG): Generation of cytotoxic T-cells is BCG strain dependent

Introduction: Forty years ago Zbar and colleagues demonstrated that bacillus calmette guerin (BCG) is capable of provoking an immune response against experimentally induced tumors. The conditions for successful tumor immunity were defined by a i) limited number of tumor cells in ii) close contact with a iii) sufficient number of bacteria and iv) the ability of the organism to mount a BCG specific immune response. These findings led to the development of what is currently the standard of care for the treatment of patients with non-muscle invasive bladder cancer. Whether the genetic drift between BCG strains that are routinely used in treatment protocols for bladder cancer affects the generation of successful tumor immunity is unknown. Here we compared two of the commonly used BCG strains (Connaught and Tice) in the treatment of bladder cancer in an animal model. Methods: Naive or bladder cancer bearing (orthotopic implantation of syngeneic MB49 cells) Bl/6 mice received either a single s.c. injection or weekly intravesical instillation of 107 CFUs of BCG Tice or Connaught. Twelve days after the 4th intravesical treatment or after the single s.c. immunization, the bladders, spleens and draining lymph nodes (DLN) were removed, enzymatically digested and the resulting cell suspensions analyzed by flow cytometry, including assessment of BCG specific CD8+ T-cells. Lymph node extracts were cultivated for the enumeration of BCG CFUs. Tumor bearing animals were assessed for their overall survival. Results: In non-tumor bearing animals, BCG Connaught lead to a more robust influx of adaptive immune cells into the bladder and primed significantly more BCG specific cytotoxic CD8+ T-cells. Compared to BCG Connaught, BCG Tice was less capable to disseminate into the draining lymph nodes (DLN), and induced less Th1 polarized CD4+ T-cells in the bladder, DLN and spleens, as assed by intracellular T-bet staining. These findings were independent of BCG preparation (clinical grade versus laboratory grade) and were seen for identical treatment doses. Finally, mice, orthotopically challenged with MB49 bladder cancer cells, showed significantly better survival if treated with BCG Connaught as compared to BCG Tice. Conclusion: Here we show that different BCG strains significantly impact the immunological response of adaptive immunity. Along with a stronger Th1 immune response, favoring the generation of cytotoxic T-cells, BCG Connaught improves survival as compared to BCG Tice in vivo. These findings implicate potential consequences for clinical practice and corroborate testing of different BCG strains in prospective clinical trials. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5386. doi:1538-7445.AM2012-5386

BCG-Mediated Bladder Cancer Immunotherapy: Identifying Determinants of Treatment Response Using a Calibrated Mathematical Model

Intravesical Bacillus Calmette Guérin (BCG) immunotherapy is considered the standard of care for treatment of non-muscle invasive bladder cancer; however the treatment parameters were established empirically. In order to evaluate potential optimization of clinical parameters of BCG induction therapy, we constructed and queried a new mathematical model. Specifically, we assessed the impact of (1) duration between resection and the first instillation; (2) BCG dose; (3) indwelling time; and (4) treatment interval of induction therapy – using cure rate as the primary endpoint. Based on available clinical and in vitro experimental data, we constructed and parameterized a stochastic mathematical model describing the interactions between BCG, the immune system, the bladder mucosa and tumor cells. The primary endpoint of the model was the probability of tumor extinction following BCG induction therapy in patients with high risk for tumor recurrence. We theoretically demonstrate that extending the duration between the resection and the first BCG instillation negatively influences treatment outcome. Simulations of higher BCG doses and longer indwelling times both improved the probability of tumor extinction. A remarkable finding was that an inter-instillation interval two times longer than the seven-day interval used in the current standard of care would substantially improve treatment outcome. We provide insight into relevant clinical questions using a novel mathematical model of BCG immunotherapy. Our model predicts an altered regimen that may decrease side effects of treatment while improving response to therapy.

MP39-08 A LISTERIOLYSIN EXPRESSING BCG WITH FAVOURABLE IMMUNOGENICITY AND PRECLINICAL TOXICITY AS A NOVEL TREATMENT FOR NON-MUSCLE INVASIVE BLADDER CANCER

INTRODUCTION AND OBJECTIVES: The molecular profile of bladder cancer has been suggested to play a critical role in prognosis and treatment response. A greater understanding of the somatic mutations that arise, and co-exist, in advanced tumors could aid in the development of targetable therapies for bladder cancer. METHODS: Fifty patients who underwent surgery for pT2+ urothelial carcinoma of the bladder with very high risk pathologic features and adequate tumor volume for DNA extraction were identified for whole exome sequencing of a set of 422 genes selected to represent the cancer genome. Demographic and clinical data were recorded. Known hotspot bladder cancer mutations (e.g. FGFR3, PIK3CA, KRAS, HRAS) were analyzed using standard Sanger sequencing. Whole genome sequencing using Solexa sequencing technology was completed. Bioinformatic analysis was subject to a rigorous analysis pipeline with multiple data filtering steps. Mutations were categorized by type, stratified against previously identified cancer loci in the COSMIC database, and evaluated in pathway analysis and co-mutation plots. RESULTS: Median age was 64 years and 67% of subjects were male. At cystectomy, 36% had positive nodes, 33% were T3, and 28% were T4. With a median follow-up of 1.4 years, 45% developed metastases and 24% died of bladder cancer, demonstrating the very high risk nature of the cohort. Sequencing of 422 genes and application of the multistep filtering algorithm revealed a core set of 212 mutations. When compared to the COSMIC database, higher mutation rates were seen in several genes including PIK3CA, NOTCH2, MSH2, APC and p53. Pathway analysis demonstrated highly mutated pathways including the PI3K/mTOR pathway, the MAPK/ERK pathway, the cell cycle regulators, and epigenetic regulators. Co-mutation analysis showed frequent co-occurrence of mutations in RB and P53 as well as NF1 and PIK3CA. CONCLUSIONS: Discovery phase analysis of the somatic mutations in 50 very high risk MIBC specimens revealed several interesting mutation patterns. These patterns may be useful for designing systemic therapy regimens for patients at very high risk of disease metastasis and death.

Abstract 3181: The genomic evolution of prostate cancer under the selective pressure of anti-androgen therapy.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Background: The implementation of novel technologies such as array comparative genomic hybridization (aCGH) and next-generation sequencing has led to a deeper understanding of the genomic nature of cancer. However, these analyses have classically been done without respecting intra-tumor heterogeneity. Here, we applied a methodology that allows us analyzing the genomic profile of distinct tumor populations from individual tumors and their clonal evolution during the progression to castration-resistant disease. Methods: Matched pre- and post- hormone treated fresh frozen and/or formalin fixed prostate cancer samples were selected from our biobank. Clonal tumor populations were flow-sorted according to their nuclear DNA content. Sorted tumor populations were subjected to whole genome CGH and to full exome sequencing analyses by the use of Agilent SurePrint 2x400k microarrays and the SureSelect All Exon Kit, respectively. Results: The genomic analyses of the tumor samples underscore the presence of significant intra-tumoral heterogeneity. The analysis of matched tumor specimens allowed us to identify two particular patterns of tumor evolution during the progression after treatment: First, a more parallel pattern of tumor evolution, in which the ancestor population is breeding multiple aneuploid tumor clones. In this case, only the 2N ancestor population is able to withstand therapy by the acquisition of few specific genomic aberrations whereas the aneuploid populations are eradicated. Second, a more sequential pattern of tumor evolution with a tumor population that evolves out of a continuous line of clones. This population shows increasing signs of genomic instability over time, with a punctual event of chromothripsis (a massive destruction and rearrangement of chromosomal structures) resulting in castration-resistant clonal tumor populations. Conclusions: Genomic profiling of distinct clonal tumor populations during prostate cancer progression allows for analysis of intra-tumoral heterogeneity and the underlying clonal evolution. Importantly, this approach identifies genomic aberrations that were selected for under the pressure of hormone ablation therapy. Citation Format: Joel R. Gsponer, Tanja Dietsche, Alexander Rufle, Elisabeth Lenkiewicz, Tobias Zellweger, Alexander Bachmann, Daniel D. Von Hoff, M T. Barrett, Cyrill Rentsch, Christian Ruiz, Lukas Bubendorf. The genomic evolution of prostate cancer under the selective pressure of anti-androgen therapy. [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 3181. doi:10.1158/1538-7445.AM2013-3181

Abstract 3167: Deciphering the genomic heterogeneity in malignant melanoma by genomic profiling of clonal tumor populations.

1) Background Melanoma is a heterogeneous disease and even though consistent genetic patterns among different subtypes have been revealed, clinical trials have failed to significantly improve survival. However, most of the genomic studies do not take into consideration the underlying genomic heterogeneity. In this study, we used genomic profiling of sorted clonal tumor populations in order to investigate the genomic heterogeneity and the clonal evolution in malignant melanoma. 2) Methods Multiple biopsies from melanoma patients were subjected to flow-sorting based on DNA content. The tumor specific marker SOX10 was used as an additional parameter to exclude contribution of normal tissue. Resulting clonal tumor populations were genomically characterized by usage of high resolution aCGH. A TMA was constructed for validation of the findings. 3) Results DNA content based flow sorting of small human melanoma biopsies was successfully implemented and revealed the co-existence of distinct clonal populations (diploid as well as aneuploid) within these samples. The use of the additional marker SOX10 allowed us to uncover and sort pure diploid tumor populations from diploid fractions admixed with normal cells. These findings were confirmed by aCGH. 4) Conclusions Human malignant melanoma is composed of different clonal populations with population-specific genomic aberrations. The use of SOX10 allowed unraveling of pure tumor populations within the diploid peaks, which would have been obscured by the use of DNA content alone. Further genomic analyses of these sorted clonal tumor populations are fundamental for the understanding of the genomic heterogeneity and its potential impact on metastasis and therapy response in malignant melanoma. Citation Format: Thomas Lorber, Tanja Dietsche, Joel Gsponer, Alexander Rufle, Michael Barret, Lukas Sommer, Katharina Glatz, Christian Ruiz, Lukas Bubendorf. Deciphering the genomic heterogeneity in malignant melanoma by genomic profiling of clonal tumor populations. [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 3167. doi:10.1158/1538-7445.AM2013-3167