3041 Background: Profiling of targetable genetic alterations within molecular tumor boards (MTB) guides for personalized treatment selection in patients with advanced cancers. During therapy, response is typically assessed by CT scans or MRI, which often have suboptimal sensitivity and specificity. Circulating tumor DNA (ctDNA) from blood plasma has emerged as a promising biomarker for noninvasive profiling of tumor mutational landscapes and disease monitoring. Here, we applied a pan-cancer next-generation sequencing (NGS) technology to assess the role of ctDNA for comprehensive tumor genotyping, early response prediction, and characterization clonal heterogeneity in patients receiving MTB recommended therapies. Methods: We developed and applied a custom targeted NGS approach (ExTARGET), which covers 266 genes across a 540 kb genomic region, to 157 plasma samples obtained at distinct milestones from 57 patients with diverse solid cancers. Plasma samples from healthy individuals ( n = 24) were used to determine the specificity of our technology. Results: We identified variants in 96% of baseline plasma samples by ctDNA profiling, with a median of 7 mutations per patient (range: 1-41). Most frequently mutated genes included KRAS (35%), BRAF (24%), ERBB2 (22%) and TP53 (22%). Targetable tumor variants that led to treatment recommendations within the MTB were found non-invasively in 69% of patients. Longitudinal monitoring of baseline ctDNA variants in on-treatment samples, obtained early during therapy ( n = 21), revealed that ctDNA dynamics were predictive of disease progression and preceded radiological/clinical progression in 8/19 (42%) patients. All patients with increasing ctDNA levels early during treatment showed radiologic disease progression in subsequent CT scans. On the other hand, an early decrease of ctDNA levels was associated with durable disease control in most patients and significantly favorable progression-free survival ( p = 0.008; HR = 0.1, 95%CI: 0.02-0.6). Next, we explored temporal clonal heterogeneity in plasma samples collected from 16 patients with disease progression following MTB-recommended therapies. We observed substantial clonal evolution over time, with all samples harboring at least one emerging variant. Among these emerging alterations, 19% were classified as ‘oncogenic’ and 5% were identified as potentially targetable. Conclusions: We here developed an NGS-based technology for ctDNA profiling in heavily pretreated patients receiving MTB-recommended therapies. Non-invasive genotyping from plasma robustly identifies targetable aberrations and allows comprehensive tumor genotyping. Monitoring of ctDNA during treatment and at disease progression facilitates early prediction of treatment response and profiling of temporal clonal heterogeneity that could enable subsequent treatment selection.

INTRODUCTION:Neuroendocrine neoplasms (NENs) are rare and biologically heterogeneous tumors with limited evidence-based systemic treatment options, particularly in advanced disease stages. Molecular Tumor Boards (MTBs) offer an interdisciplinary framework for interpreting genomic alterations and identifying personalized treatment strategies. METHODS:We conducted a retrospective two-center analysis of patients with NENs discussed at the MTBs of the University Medical Center Freiburg and the Technical University of Munich between 2019 and 2024. Clinical characteristics, molecular profiling results, MTB-based therapy recommendations, treatment implementation, and outcomes were evaluated. Overall survival (OS) was analyzed using a predefined 6-month landmark approach to account for immortal time bias. Treatment efficacy was further assessed using progression-free survival (PFS) and PFS2/PFS1 ratio. RESULTS:A total of 87 patients were discussed at both MTBs, 74 of whom underwent molecular profiling. Actionable therapy recommendations were issued for 58 patients, and 20 patients ultimately received MTB-guided therapy. Molecular alterations frequently involved DNA damage repair pathways, immune-related biomarkers, and signaling cascades relevant to targeted therapy. 6-month landmark OS analysis demonstrated significantly improved OS for patients receiving MTB-guided therapy. At the individual level, 8 of 20 treated patients achieved a PFS2/PFS1 ratio >1.3. CONCLUSION:Molecular-guided precision oncology can provide clinically meaningful benefit for selected patients with NENs, despite limited overall implementation rates. Earlier integration of molecular profiling may increase the feasibility and impact of personalized treatment approaches in these rare tumor entities.

Abstract Circulating tumor DNA (ctDNA) from blood plasma has emerged as a promising biomarker for noninvasive profiling of tumor mutational landscapes and disease monitoring across cancers. In this study, we developed a targeted next-generation sequencing approach to explore the role of ctDNA for comprehensive tumor genotyping, early response prediction, and characterization of clonal heterogeneity in patients with advanced and rare cancers treated within molecular tumor boards. We applied our technology to 157 plasma specimens from 57 patients at distinct disease milestones and detected tumor variants in 96% of baseline samples, with 65% of them harboring actionable aberrations. Longitudinal monitoring of baseline mutations in on-treatment plasma revealed that ctDNA dynamics were significantly associated with clinical outcomes and enabled early prediction of disease progression. Finally, we observed substantial clonal heterogeneity over time, identifying emerging mutations in all analyzed plasma samples obtained at progression, including potentially targetable variants for subsequent personalized therapies.

Immunotherapy has revolutionized the treatment of solid cancers in recent years. However, T-cell lymphomas (T-NHLs) originate from immune cells themselves and are biologically heterogeneous, rendering investigations of immune checkpoint inhibitor (ICI) mechanisms of action complex. While case reports and individual Anaplastic Large Cell Lymphoma (ALCL) cases enrolled in T-NHL trials demonstrated favourable responses to ICI, hyperprogression was observed in other T-NHL subtypes. We therefore utilized a syngeneic mouse model of ALK+ ALCL to investigate immune surveillance and ICI-induced immune response. Transplantation experiments combined with depletion of relevant immune axes revealed that ALCL immune surveillance is mediated by CD4+ T cells and NK cells. Innate and adaptive immune cell infiltration was confirmed on a large series of primary human ALK+ ALCL samples. ICI monotherapy demonstrated robust efficacy in murine ALCL, inducing complete remissions in approximately 50% of treated animals. Mechanistically, PD-L1 blockade reversed Treg-mediated immunosuppression and increased the frequency of circulating effector CD8+ T lymphocytes, thereby prolonging survival significantly. Importantly, CD4+ T cells proved indispensable for driving and sustaining immunotherapy-induced anti-tumour responses in murine ALCL. CD4+ T cells of non-responder animals exhibited an exhausted phenotype and a transcriptomic Th22-like signature, implicating persistent T-cell exhaustion and polarization as a meaningful immune-evasion mechanism. Our findings uncover CD4+ T cells as key players in spontaneous and immunotherapy-mediated anti T-cell lymphoma immunity, which demonstrates the critically needed preclinical proof-of-concept for the safe and effective use of immunotherapy for ALCL.

Despite therapeutic advancements, approximately 50% of advanced melanoma patients succumb to metastatic disease. Molecular tumor boards (MTB) aim to identify targetable molecular alterations to guide individualized treatment strategies. Yet, real-world data on patient selection, referral timing, recommendation rates, implementation, and clinical impact remain limited. In this exploratory retrospective bicenter analysis, we evaluated 80 patients with advanced melanoma who presented at institutional MTBs of two comprehensive cancer centers. Clinical and molecular tumor data were analyzed using bioinformatic tools to characterize mutation profiles, treatment recommendations, and their real-world implementation. Most patients (88.3%) had stage IV melanoma at the time of presentation and had received a median of three prior systemic treatment lines. Actionable treatment recommendations were formulated in 77.9% of eligible cases, yet only 33.7% of recommendations were implemented. Non-implementation was most commonly attributable to early patient death or regulatory barriers. Importantly, when recommended therapies were applied, patients experienced significantly improved progression-free survival (7.85 vs. 4.34 months; PFS ratio 1.8) and overall survival (10.64 vs. 5.06 months) compared with patients in whom recommended treatments were not implemented. Among patients with implemented MTB recommendations (n = 26), the median intra-patient PFS ratio was 1.68, and 14 of 26 patients (53.8%) achieved a PFS ratio ≥ 1.3. These findings indicate that MTBs frequently generate clinically actionable recommendations for metastatic melanoma, but late-stage referral substantially limits their real-world implementation. When applied, molecularly guided treatment strategies may confer meaningful clinical benefit, underscoring the importance of earlier integration of MTBs into melanoma care pathways.

ABSTRACT:B-cell receptor (BCR) signaling is a key determinant of chronic lymphocytic leukemia (CLL) pathophysiology. CD49d, the α4 subunit of the very late antigen 4 integrin, can be activated by BCR signals; however, its role in modulating BCR functionality remains unknown. We used knockout mouse models and primary human CLL stratified by CD49d expression to address this aspect. CD49d was required for bone marrow (BM) infiltration and shaped BM infiltration patterns and patient outcomes in human CLL. In TCL1 transplantation models, the loss of CD49d abrogated BM homing and leukemic cell positioning within splenic niches. At the cellular level, CD49d-deficient murine TCL1 transgenic cells and human CD49d-low CLL cells failed to form efficient immune synapses with antigen-presenting membranes. Transcriptome analyses identified CD49d-dependent regulation of actin-associated pathways and distinct signatures of BCR responsiveness in both human and mouse cells. Consistently, CD49d-low human CLL cells displayed aberrant actin remodeling following BCR stimulation, and a second aggressive murine CLL model reproduced the actin and engraftment defects. Kinome profiling linked impaired antigen-induced BCR responses in CD49d-deficient murine cells to altered kinase activity, and pharmacologic actin perturbation phenocopied CD49d loss. In human CD49d-low CLL cells, a desynchronization of BCR-related downstream Syk and PLCɣ2 activation was found. Mechanistically, the CD49d-BCR interplay involved their colocalization, and CD49d converged with BCR signaling on a focal adhesion kinase-actin axis. In summary, our findings establish CD49d as a key regulator of BCR functionality in CLL, linking integrins to cytoskeletal dynamics and antigen responsiveness.

Background/Objectives: ALK+ Anaplastic Large Cell Lymphoma (ALCL) is an aggressive T-cell lymphoma that is characterized by expression of the Anaplastic Lymphoma Kinase (ALK), which is induced by the t(2;5) chromosomal rearrangement, leading to the expression of the NPM-ALK fusion oncogene. Most previous preclinical models of ALK+ ALCL were based on overexpression of the NPM-ALK cDNA from heterologous promoters. Due to the enforced expression, this approach is prone to artifacts arising from synthetic overexpression, promoter competition and insertional variation. Methods: To improve the existing ALCL models and more closely recapitulate the oncogenic events in ALK+ ALCL, we employed CRISPR/Cas-based chromosomal engineering to selectively introduce translocations between the Npm1 and Alk gene loci in murine cells. Results: By inducing precise DNA cleavage at the syntenic loci on chromosome 11 and 17 in a murine IL-3-dependent Ba/F3 reporter cell line, we generated de novo Npm-Alk translocations in vivo, leading to IL-3-independent cell growth. To verify efficient recombination, we analyzed the expression of the NPM-ALK fusion protein in the recombined cells and could also show the t(11;17) in the IL-3 independent Ba/F3 cells. Subsequent functional testing of these cells using an Alk-inhibitor showed exquisite responsiveness towards Crizotinib, demonstrating strong dependence on the newly generated ALK fusion oncoprotein. Furthermore, a comparison of the gene expression pattern between Ba/F3 cells overexpressing the Npm-Alk cDNA with Ba/F3 cells transformed by CRISPR-mediated Npm-Alk translocation indicated that, while broadly overlapping, a set of pathways including the unfolded protein response pathway was increased in the Npm-Alk overexpression model, suggesting increased reactive changes induced by exogenous overexpression of Npm-Alk. Furthermore, we observed clustered expression changes in genes located in chromosomal regions close to the breakpoint in the new CRISPR-based model, indicating positional effects on gene expression mediated by the translocation event, which are not part of the older models. Conclusions: Thus, CRISPR-mediated recombination provides a novel and more faithful approach to model oncogenic translocations, which may lead to an improved understanding of the molecular pathogenesis of ALCL and enable more accurate therapeutic models of malignancies driven by oncogenic fusion proteins.

ObjectivesMolecular tumor boards (MTBs) have become an integral component of precision oncology, yet data on their real-world impact in urologic cancers are limited. This study aimed to characterize the molecular landscape of urologic malignancies presented to the MTB at the University Medical Center Freiburg and to evaluate the frequency and clinical relevance of genomic alterations across tumor entities.MethodsWe retrospectively analyzed 118 patients with histologically confirmed urologic tumors presented at the Freiburg MTB between Januar 2019 and December 2024. Comprehensive molecular profiling was performed using next-generation sequencing (TruSight Oncology 500 or whole exome sequencing). Data were analyzed for mutation frequency, tumor mutational burden (TMB), and co-occurrence patterns, and integrated with clinical data to guide therapy recommendations.ResultsSomatic mutations were identified in 90.6% of cases. Frequent alterations included TP53, BRCA2, KMT2D, and ATM, with DNA damage response and chromatin remodeling pathways commonly affected. Prostate cancers showed high rates of BRCA2 and APC co-mutations, indicating potential benefit from combined PARP and Wnt-targeted therapies. In bladder and upper tract urothelial carcinomas (UTUC), KMT2C co-occurred with genes such as SPTA1 and LRP1B, suggesting a hypermutated, immunoresponsive phenotype. Renal tumors frequently harbored alterations in VHL, PBRM1, and SETD2. Rare entities such as penile and testicular tumors displayed distinct mutation patterns, including BRCA1/2 and MMR gene alterations.ConclusionsComprehensive molecular profiling in a MTB setting reveals distinct and therapeutically relevant mutational patterns across urologic cancers. These data support the integration of MTBs into clinical workflows and highlight the potential of co-mutational signatures to guide personalized treatment strategies.

e17655 Background: Molecular tumor boards (MTBs) play a crucial role in personalized medicine in Germany, guiding the treatment of patients who have exhausted standard options. To generate evidence that can inform future therapeutic recommendations, data on molecular characteristics and treatment outcomes are needed. Methods: This study retrospectively analyzes the real-world data including the molecular landscape, MTB recommendations and their corresponding biomarkers as well as outcomes of patients with gynecologic malignancies (breast-, cervical-, endometrial-, ovarian-, vulvar cancer and uterine sarcoma who were discussed at the Molecular Tumor Board Freiburg (MTB-FR). Results: From 2019 to 2022, 262 cases of gynecologic malignancies (corresponding to 249 individual patients) were referred to the MTB-FR. N=229 cases (87.4%) received a recommendation for personalized diagnostics at the protein, DNA and/or transcriptomic level and were included in the analysis. This cohort was characterized as relatively young yet highly pretreated, with a significant unmet clinical need, as reflected by a mean age of 53.3 years and a mean of 3.1 prior lines of systemic treatment. Personalized diagnostics resulted in at least one treatment recommendation in n=170/229 (74.2%) cases, primarily off-label therapies. In 50.6% of cases, at least one potentially matching clinical trial could be identified. Molecularly informed therapy was implemented in n=63/170 cases (37.1%), while n=81/170 cases (47.6%) received none of the recommended treatments, predominantly due to deterioration in health status. In 15.3% of cases, the implementation of the recommended treatment was unclear due to loss to follow-up. The most prevalent implemented therapeutic agents were antibody-drug conjugates (25.7%) and immune checkpoint inhibitors (17.1%). 75.4% of implemented off-label treatments were supported by evidence from the same tumor entity (NCT level m1A-C). Clinical trials accounted for 12.9% of implemented treatments. In our retrospective analysis, patients who received an MTB-recommended therapy (n=61) exhibited a significantly longer median overall survival (OS) of 19 months compared to 6 months for those who did not receive an MTB-recommended therapy (n=59, log-rank p=0.0002). Conclusions: These results underscore the benefit of MTB referral in patients with gynecologic malignancies and highlight the importance of early intervention in this setting. Additional analysis and progression-free survival data are expected.

Aberrant gene expression patterns in acute myeloid leukemia (AML) with balanced chromosomal translocations are often associated with dysregulation of epigenetic modifiers. The AML1/ETO (RUNX1/MTG8) fusion protein, caused by the translocation (8;21)(q22;q22), leads to the epigenetic repression of its target genes. We aimed in this work to identify critical epigenetic modifiers, on which AML1/ETO-positive AML cells depend on for proliferation and survival using shRNA library screens and global transcriptomics approaches. Using shRNA library screens, we identified 41 commonly depleted genes in two AML1/ETO-positive cell lines Kasumi-1 and SKNO-1. We validated, genetically and pharmacologically, DNMT1 and ATR using several AML1/ETO-positive and negative cell lines. We also demonstrated in vivo differentiation of myeloblasts after treatment with the DNMT1 inhibitor decitabine in a patient with an AML1/ETO-positive AML. Bioinformatic analysis of global transcriptomics after AML1/ETO induction in 9/14/18-U937 cells identified 973 differentially expressed genes (DEGs). Three genes (PARP2, PRKCD, and SMARCA4) were both downregulated after AML1/ETO induction, and identified in shRNA screens. In conclusion, using unbiased shRNA library screens and global transcriptomics, we have identified several driver epigenetic regulators for proliferation in AML1/ETO-positive AML. DNMT1 and ATR were validated and are susceptible to pharmacological inhibition by small molecules showing promising preclinical and clinical efficacy.

Acute myeloid leukemia (AML) is one of the most common leukemias in adults. Still, treatment poses a significant challenge, especially in elderly patients, who are unfit for standard chemotherapy. For these patients, hypomethylating agents (HMA) such as azacytidine (AZA) and decitabine (DAC) are often the only available treatment. Nevertheless, resistance frequently develops, and strategies to overcome these remain elusive. Moreover, the exact mechanisms of HMA action, potential response modulators, and reliable biomarkers remain to be defined. To identify modifiers to HMA response in AML cells, we conducted an inducible-pooled short-hairpin RNA (shRNA)-based library screen, targeting all epigenetic regulation genes listed in the KEGG pathway. After ten days of treatment and shRNA induction, the gene expression profiles were linked to treatment response. Candidate genes were further validated through Western Blot and growth competition assays using FACS. We further determined the global methylation levels employing EPIC 450K BeadChip and performed functional enrichment analysis (GSEA). Cell cycle and DNA damage responses were compared to cytarabine (CYT) using FACS and high-throughput laser-scanning microscopy. Our screen identified crucial genes influencing HMA sensitivity, including DNMT1 itself, chromatin modulators, as well as DNA damage response (DDR) genes such as members of the PARP family and BRCA1. DNMT1 knockdown (kd) significantly increased the efficacy of AZA and DAC, causing higher G2/M phase arrest (nearly 30% vs. 18% in single treatment) with a significant drop in AML cell viability (from 60% to 20% over eight days). This effect was also prominent in global methylation levels. While AZA treatment alone decreased DNA methylation, DNMT1 kd enhanced this effect correlating with cell depletion in a growth competition assay. GSEA analysis showed increased interferon-γ pathways in hypomethylated regions, though Sting kd did not reduce HMA efficacy. Moreover, all compounds, HMA and CYT, triggered a similar DNA damage (gamma-H2AX) (70% compared to CTR). However, CYT caused larger and brighter gamma-H2AX-foci, indicating more severe damage compared to HMA. This damage could be caused by replication fork termination in all substances. Further analysis of the DDR pathway showed that all compounds activated pATM and pATR, however, with HMAs specifically increasing pATM activity and 53BP1 activation, leading to rapid but error-prone non-homologous end joining (NHEJ) repair. DNMT1 kd further enhanced the pATM-53BP1 pathway activation. Again, DNMT1 kd enhanced the pATM-53BP1 pathway choice. In summary, our results demonstrate the central role of DNMT1 in HMA response in AML. While increasing HMA concentration leads to cytotoxicity, combining HMAs with additional DNMT1 inhibitors shows promise for enhancing HMA-based treatment. We already could confirm in preliminary experiments the synergistic effects of HMA with other inhibitors targeting DNMT1 and are currently combining the new DNMT1 inhibitor GSK-3484862 with AZA and DAC. Furthermore, we highlighted the induction of the pATM-53BP1 axis and its role in NHEJ repair, suggesting that modulating this pathway could potentially improve treatment outcomes.

The field of antibody-based therapeutics has grown significantly in recent years, with targeted antibodies emerging as a potentially effective approach to personalized therapies. Such therapies could be particularly beneficial for complex, highly individual diseases such as cancer. However, progress in this field is often constrained by the extensive search space of amino acid sequences that form the foundation of antibody design. In this study, we introduce a novel reinforcement learning method specifically tailored to address the unique challenges of this domain. We demonstrate that our method can learn the design of high-affinity antibodies against multiple targets in silico, utilizing either online interaction or offline datasets. To the best of our knowledge, our approach is the first of its kind and outperforms existing methods on all tested antigens in the Absolut! database.

Antibodies offer great potential for the treatment of various diseases. However, the discovery of therapeutic antibodies through traditional wet lab methods is expensive and time-consuming. The use of generative models in designing antibodies therefore holds great promise, as it can reduce the time and resources required. Recently, the class of diffusion models has gained considerable traction for their ability to synthesize diverse and high-quality samples. In their basic form, however, they lack mechanisms to optimize for specific properties, such as binding affinity to an antigen. In contrast, the class of offline Reinforcement Learning (RL) methods has demonstrated strong performance in navigating large search spaces, including scenarios where frequent real-world interaction, such as interaction with a wet lab, is impractical. Our novel method, BetterBodies, which combines Variational Autoencoders (VAEs) with RL guided latent diffusion, is able to generate novel sets of antibody CDRH3 sequences from different data distributions. Using the Absolut! simulator, we demonstrate the improved affinity of our novel sequences to the SARS-CoV spike receptor-binding domain. Furthermore, we reflect biophysical properties in the VAE latent space using a contrastive loss and add a novel Q-function based filtering to enhance the affinity of generated sequences. In conclusion, methods such as ours have the potential to have great implications for real-world biological sequence design, where the generation of novel high-affinity binders is a cost-intensive endeavor.

Abstract The docking protein GAB2 binds to growth factor, cytokine and antigen receptors via the adaptor GRB2. Thereby, GAB2 amplifies the signaling output of the SHP2/Ras/ERK, PI3K/AKT and STAT5 pathways, leading to survival, proliferation and migration. Beside these physiological functions, GAB2 is often overexpressed or hyperphosphorylated in different types of cancer, in particular melanoma, breast cancer and various leukemia entities. Previous studies demonstrated that mice with constitutive Gab2 deficiency are protected against breast cancer, acute and chronic myeloid leukemia driven by HER2, BCR::ABL1 and FLT3-ITD, respectively. While these studies support a critical role in tumor initiation, nothing is known about the relevance of GAB2 for tumor maintenance and progression. To this end, we have developed two novel conditional loss- and gain-of-function mouse models to further analyze the role of GAB2 in cancer. In the first model, the transgenic GAB2 mouse, GAB2 is expressed under the control of the TET-O promotor, allowing the tetracycline dependent expression in tissues expressing a tetracycline trans activator (tTA). We have already started by crossing in the SCLtTA mouse, in which tTA is expressed under the control of the murine stem cell leukemia 3’ enhancer. Here we show that the expression of transgenic GAB2 is tightly regulated by tetracycline and restricted to hematopoietic cells. This system is now perfectly suited to analyze the role of GAB2 in hematologic malignancies. By expressing tTA under different promotors, we propose that GAB2 overexpression can be directed to other organs or cell types. Combining this mouse line with cancer mouse models will allow to study the role of GAB2 in different cancer entities. With the second mouse model, the conditional Gab2 KO mouse, it is possible to study the therapeutic potential of GAB2 impairment in vivo. In this mouse, exon three of the Gab2 gene is flanked by LoxP sites. This allows for its CRE recombinase mediated deletion, leading to GAB2 deficiency. The combination of this mouse model with inducible and tissue specific CRE strains will allow to analyze the role of GAB2 in various cancer mouse models. To demonstrate the efficient conditional deletion of exon 3, we first crossed in the tamoxifen inducible ROSA26 CreERT2 mouse line. So far, we were able to show the functionality of this system in vitro in mouse embryonic fibroblasts (MEFs) generated from the conditional Gab2 KO mouse. In a next step we will verify the results in vivo and will cross this mouse line with a mouse model for Chronic Myeloid Leukemia (CML) to investigate the therapeutic potential of GAB2 in CML. In summary, we are convinced that these two novel mouse models will help to identify GAB2 as a potential target or biomarker in various cancer entities. In particular, the conditional approach will allow to alter GAB2 expression in already established tumors, thus mimicking pharmacological targeting. Citation Format: Moritz Angel, Vanessa Klappstein, Jule Schrimpf, Melanie Langhammer, Khalid Shoumariyeh, Cornelius Miething, Ulrich Kloz, Brittney Armstrong, Franciscus van der Hoeven, Tilman Brummer, Sebastian Halbach. Novel mouse models to study the role of the docking protein GAB2 in general and in cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5374.

Despite major advances in molecular profiling and classification of primary brain tumors, personalized treatment remains limited for most patients. Here, we explored the feasibility of individual molecular profiling and the efficacy of biomarker-guided therapy for adult patients with primary brain cancers in the real-world setting within the molecular tumor board Freiburg, Germany. We analyzed genetic profiles, personalized treatment recommendations, and clinical outcomes of 102 patients with 21 brain tumor types. Alterations in the cell cycle, BRAF, and mTOR pathways most frequently led to personalized treatment recommendations. Molecularly informed therapies were recommended in 71% and implemented in 32% of patients with completed molecular diagnostics. The disease control rate following targeted treatment was 50% and the overall response rate was 30%, with a progression-free survival 2/1 ratio of at least 1.3 in 31% of patients. This study highlights the efficacy of molecularly guided treatment and the need for biomarker-stratified trials in brain cancers.