Copland, John A.

Abstract Gastrointestinal (GI) cancers are rising in people < 50 and remain major causes of cancer mortality despite therapeutic advances. Chimeric antigen receptor T (CART) cell therapy has transformed treatment of hematological cancers. However, its efficacy in GI cancers has been hindered by antigen heterogeneity and immunosuppressive cancer associated fibroblasts (CAFs) in the tumor microenvironment (TME.) Here we aimed to 1) study CART-CAF interactions and 2) engineer CART cells capable of eliminating CAFs to overcome their inhibitory role and enhance their antitumor activity in GI cancers. We first analyzed primary CAFs from 20 GI cancer patients. CAFs showed high fibroblast activation protein (FAP) expression and significantly suppressed T cells proliferation (26-77%, p≤0.0001). We next generated CART cells capable of safely eliminating both GI cancer cells and CAFs. To target cancer cells, we developed a novel nanobody (VHH)-based CAR against Claudin18.2, a GI cancer specific target. To avoid off-tumor toxicity in healthy FAP+ tissues, we incorporated an inducible FAP-CAR using the synNotch platform, enabling conditional targeting upon engagement with Claudin18.2+ cells, restricting FAP targeting within the TME. VHH Claudin18.2 CART cells showed superior specificity and efficacy vs scFv-based CART cells (hu8E85 or zolbetuximab). In Claudin18.2+ SNU-C2B xenografts, tumors were 92mm3 (VHH) vs 48mm3 (huE85) vs 211mm3 (zolbetuximab) on day 23 post-CART, median survival undefined vs 17 days vs 23 days respectively; p=0005. In Claudin18.2+ LS411N xenografts, tumors were 315mm3 vs 106mm3 vs 382 mm3 respectively at 23 days post-CART, median survival undefined vs 19 days vs undefined respectively; p=0004. VHH Claudin18.2 CART cells showed no off-tumor effects, while hu8E85 CART induced significant toxicity. We next established a co-engraftment model. NSG mice received 1x106 SNU-C2B and 6x106 CAFs from a GI cancer patient. At 500 mm3 tumors, mice received 5x106 VHH Claudin18.2 or inducible Claudin18.2/FAP CART. Dual-targeting CART cells showed greater antitumor response (728mm3 vs 320mm3, p=0.0011 at day 20 post-CART), expansion (61 vs 2,350 CART/µl of blood, p=0.0037), and tumor infiltration (8.71 x 105 vs 1.03 x 106 CART/g of tumor, p<0.0001). This was also observed in gastric, colon, and pancreatic PDX models, with no observable off-tumor cytotoxic effects with inducible dual-targeting Claudin18.2/FAP CART. Our findings demonstrate that our novel VHH-based Claudin18.2 CART cells are highly specific and effective against GI malignancies, and that inducible Claudin18.2/FAP dual-targeting CART cells safely remodel the TME into an immune-permissive state. This approach represents a mechanistically innovative and translationally relevant strategy to overcome CAF-mediated immunosuppression, enhance CART cell efficacy, and improve clinical outcomes in refractory solid tumors. Citation Format: Omar L. Gutierrez Ruiz, Jennifer Feigin, Brooke Kimball, R. Leo Sakemura, Elizabeth L. Siegler, Dominic A. Skeele, Ateka Saleh, Claudia Manriquez Roman, Ismail Can, Olivia Sirpilla, Kun Yun, Carli M. Stewart, Mehrdad Hefazi, Yoh Yamaguchi, Lionel Aurelien Kankeu Fonkoua, Long K. Mai, Truc Huynh, Sophia Y. Goldberg, Grace E. DeFranco, Sara Foote, Ekene Johnkennedy Newton Ogbodo, Hong Xia, Michael Redig, Matthew L. Matthew, Tamiel Nichole Turley, Skyeler Klinge, John Alton Copland, Saad J. Kenderian. Optimized CART cell therapy to remodel the tumor microenvironment and eliminate GI malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 1525.

Abstract Background: The cellular balance between saturated and monounsaturated fatty acids is a defining feature of tumor lipid metabolism, with SCD1 functioning as a key modulator through the production of MUFAs. Elevated SCD1 activity and MUFA accumulation have been documented in hepatocellular carcinomas, although the consequences of restricting MUFA synthesis have not been fully clarified. Methods: A selective SCD1 inhibitor, SSI-4, was evaluated across established human HCC cell lines and xenograft models. Measurements included cell viability, lipid compositional analyses, and characterization of stress response pathways at both molecular and biochemical levels. The effects of MUFA depletion were studied in vitro and in vivo, with attention to ER stress, apoptosis, ferroptosis markers, and autophagy induction. Results: SSI-4 treatment led to marked reduction in cellular MUFA content and an increase in saturated fatty acid pools. The resulting metabolic stress correlated with activation of unfolded protein response components, caspase-mediated cell death, and the upregulation of ferroptosis-associated genes. Triglyceride and MUFA levels declined precipitously, as confirmed by mass spectrometry-based lipidomics. Tumor growth was suppressed in PDX models and evidence of autophagic flux was apparent in sensitive cell lines. Variability in response highlights metabolic heterogeneity in HCC. Conclusions: Targeted disruption of MUFA biosynthesis inflicts metabolic vulnerability on HCC cells, precipitating membrane alterations and activation of multiple cell death programs. These findings recommend further investigation into metabolic interventions exploiting MUFA depletion, with consideration for stratifying patients according to lipid metabolic phenotypes. Funding: This work is supported by Mayo Clinic Comprehensive Cancer Center and the Jay and Deanie Stein Career Development Award for Cancer Research at Mayo Clinic Jacksonville and the Mayo Clinic Translational Hepatobiliary Cancer SPORE P50CA210964 Career Enhancement Program (CEP) and Florida Department of Health/Florida Cancer Innovation Fund C25C23. Citation Format: Justyna J. Gleba, Victoria N. Rios, Brian M. Necela, Skyeler M. Klinge, Matt L. Pawlush, Mike J. Redig, Aylin Alasonyalilar-Demirer, Han W. Tun, John A. Copland III, . Disrupting tumor lipid homeostasis by MUFA depletion drives cell death in HCC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 7333.

Abstract Lipid metabolism plays an important role in lung cancer growth, survival, and therapeutic resistance. Stearoyl-CoA desaturase 1 (SCD1), the enzyme that converts saturated fatty acids (SFAs) into monounsaturated fatty acids (MUFAs), represents a metabolic vulnerability since cancer cells depend on MUFAs for membrane biosynthesis, ER homeostasis, and alternative energy to glucose. SSI-4 (a.k.a MTI-301) is a selective SCD1 inhibitor currently in Phase I clinical evaluation for metastatic, unresectable, or refractory solid cancers, but its activity in non-small cell lung cancer (NSCLC) has not yet been characterized. To evaluate how NSCLC models respond to SCD1 blockade, we performed an initial screen of a panel of 17 human non-small cell lung cancer cell lines treated with 100 nM SSI-4 under defined serum conditions. Cell viability assays identified 9 responding cell lines, and dose-response studies confirmed IC50 values ranging from approximately 0.65 to 45.5 nM. Rescue experiments showed that adding oleic acid, an SCD1 regulated MUFA, reversed SSI-4-mediated growth inhibition, confirming mechanistically that this effect occurs through SCD1 blockade. Western blot analysis confirmed that SSI-4 treatment increased markers of endoplasmic reticulum (ER) stress and apoptosis in sensitive lines, consistent with disruption of lipid homeostasis. In contrast, non-responsive lines exhibited minimal induction of these stress pathways and retained viability despite treatment. Soft agar assays further showed that SSI-4 reduced anchorage-independent colony formation in responsive lines, indicating that SCD1 inhibition suppresses a key malignant growth property in these NSCLC models. Collectively, these findings demonstrate that SSI-4 selectively inhibits proliferation in a subset of NSCLC cells through an SCD1-dependent mechanism by reducing MUFA availability and activating stress and apoptotic signaling. This work establishes a framework for subsequent in vivo studies and lays the foundation for exploring SCD1 inhibition as a potential therapeutic strategy for patients with limited treatment options in NSCLC, while also advancing understanding of the mechanisms by which SCD1 supports tumor survival. Citation Format: Valeria Romina Salerno Gonzales, Lauren Antal, Tamiel Nichole Turley, John A. Copland III. Inhibition of stearoyl-CoA desaturase 1 (SCD1) by SSI-4 as a therapeutic strategy in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2942.

Triple-negative breast cancer (TNBC) remains highly aggressive and refractory to conventional treatments, underscoring the need for novel combination strategies. Here, we employed 2D and 3D in vitro models, transcriptomic profiling, and in vivo xenograft studies to evaluate the anticancer efficacy of cannabinoids combined with the terpene β-caryophyllene (BC) in resistant TNBC models. Among the tested cannabinoids, cannabichromene (CBC) exhibited the greatest potency, and its combination with BC at sub-toxic concentrations significantly reduced IC50 values, enhanced cytotoxicity in spheroids, and suppressed colony formation and migration. The combination treatment induced pronounced G1 cell cycle arrest and increased apoptotic cell death. Western blot analyses revealed downregulation of PARP, Survivin, mTOR, Vimentin, Glypican-5, and PD-L1, while RNA sequencing demonstrated suppression of proliferative and migratory signaling pathways alongside activation of apoptosis, autophagy, and ferroptosis-related pathways. In vivo, CBC + BC significantly inhibited tumor growth in MDA-MB-231 xenografts, outperforming single-agent treatments. Collectively, these findings demonstrate that BC synergistically enhances cannabinoid activity, yielding superior antiproliferative and anti-migratory effects, and highlight this combination as a promising therapeutic strategy for resistant TNBC.

Abstract GPNMB (Glycoprotein non-metastatic melanoma protein B) is a canonical transcriptional target of MiT/TFE proteins (TFEB/TFE3/MITF), expressed at low levels in normal tissues but upregulated in numerous MiT/TFE-driven tumors such as translocation RCC, alveolar soft part sarcoma and MITF-driven melanoma, where it is associated with poor prognosis. CDX-011 (CR011-MMAE) is an anti-GPNMB ADC, with demonstrated efficacy in pre-clinical models of TFE3-fusion RCC. To further characterize GPNMB functionality and value as a cell-surface therapeutic target in tRCC, we engineered cell lines with genomic deletion of GPNMB via CRSIPR-Cas9 editing. Deletion of GPNMB in PRCC-TFE3 cell lines [UOK120/UOK124] significantly decreased clonogenic growth in 2D, spheroid size and viability and tumor xenograft growth in NSG mice and was associated with a decrease in phosphorylation of mTORC1 substrates [p-P70S6K, p-4EBP1]. We then examined expression of CD44, the primary receptor for GPNMB, and a tumor-associated antigen associated with poor prognosis in many cancers. Expression of CD44 and its ligand SPP1/OPN, was significantly increased in bulk RNA-Seq data from multiple transgenic models of SFPQ-TFE3, PRCC-TFE3 and ASPSCR1-TFE3, in human tRCC cases compared to normal kidney, and in SFPQ-TFE3/ PRCC-TFE3 transgenic kidney tumors and an ASPSCR-TFE3 PDX model, by immunoblotting and IHC, with increased membrane localization. shRNA-mediated depletion of CD44 profoundly and specifically decreased clonogenicity of multiple TFE3-fusion lines, with no effect seen in ccRCC lines. In conclusion, GPNMB regulates the growth of tRCC cells, potentially via an autocrine mechanism involving its receptor CD44, and targeting GPNMB-CD44 signaling may be of therapeutic benefit in tRCC. Citation Format: Kaushal Asrani, Juhyung Woo, Kewen Feng, Thiago Vidotto, Adrianna Amaral, Vikrant Palande, Jayaprakash Mandal, Eddie Imada, Christopher Thoburn, Sangeeta Ray, Huili Li, Yasser Ged, Nirmish Singla, John A. Copland, Laura Schmidt, W. Marston Linehan, Pedram Argani, Tamara Lotan. GPNMB:CD44 signaling drives tumor progression in translocation renal cell carcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Innovations in Kidney Cancer Research: From Molecular Insights to Therapeutic Breakthroughs; 2026 Mar 13-16; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2026;86(5_Suppl_2):Abstract nr B014.

Abstract Background: Triple-negative breast cancer (TNBC) is highly aggressive subtype with poor prognosis and there is an urgent need to develop novel therapies. Deregulated cellular energetics is a known hallmark of cancer. Stearoyl-CoA desaturase-1 (SCD1), is a key enzyme in fatty acid (FA) synthesis, converting saturated to monounsaturated FA. It is upregulated in TNBC, and its expression correlates with poor survival. Hence, targeting SCD1 is a novel strategy for cancer therapy. We have developed an SCD1 inhibitor, MTI-301 and shown anti-tumor activity in murine TNBC cell lines with MTI-301 alone and in combination with paclitaxel. Here, we study the efficacy of MTI-301 in TNBC mouse model and, molecular and immunological association of SCD1 in TNBC. Methods: MTI-301 activity (10 mg/kg oral gavage daily) was evaluated in E0771 immunocompetent TNBC mouse models alone and with immune checkpoint inhibitors (ICI) and paclitaxel (anti-PD-L1 Ab 200ug/mouse; IP and 25 mg/kg IP both given 2/week). Immune markers such as CD4+ T cell and CD8+ T cell in mice tumor tissue were assessed by immunohistochemistry (IHC). Tumor volume was measured by calipers 2/week and compared between groups by ANOVA test. Molecular and immune characterization was performed in 1,581 invasive ductal (ID) TNBC patient (pt) samples tested by NGS (592-gene panel, NextSeq; WES/WTS, NovaSeq; Caris Life Sciences, Phoenix, AZ). ID-TNBC SCD1-high(H) and SCD1-low(L) RNA expression were classified as above or below the 50 percentiles, respectively. Immune cell fractions were calculated by deconvolution of WTS: Quantiseq. Pathway enrichment was determined by GSEA (Broad Inst). Statistical significance was determined using chi-square and Mann-Whitney U test with p-values adjusted for multiple comparisons (q<0.05). Results: Compared to vehicle control, MTI-301 showed significant reduction in mean tumor volume and was associated with macrophage phagocytosis and intratumor infiltration of CD4 and CD8 T cells. We have also showed that MTI-301 + anti-PD1 Ab + paclitaxel has significant antitumor activity compared to either agent alone. IHC analysis is ongoing. In real-word pt data, SCD1-H TNBC (N=791) had higher immune cell infiltration of M2 MΦ (2.95% vs. 2.58%) and neutrophils (4.5% vs. 4.1%) compared to SCD1-L (N=790), all q<0.05. SCD1-H had decreased IFNγ score (-0.29 vs -0.24), but increased MAPK activation score (-0.57 vs -1.77), all q<0.05. SCD1-H had higher levels of metabolic regulator genes (IL10, IL10RA, SOCS3, HIF1A, DUSP6, FC: 1.4-1.8), immune checkpoint genes (PDCD1, CTLA4, LAG3, TIGIT, VISTA, CD244, CD160, BTLA, HAVCR2, FC: 1.3-1.6), stem cell related genes (CD44, ALDH1A1, ALDH1A2, ALDH1A3, KLF4, NANOG, FC: 1.4-1.6) and markers of exhausted T cells (CXCL13, CD38, CD101, ENTPD1, CD69, CD103, KLRG1, PRF1, GZMB, FC: 1.2-1.7), all q<0.05. SCD1-H had enrichment of pathways related to oxidative phosphorylation, FA metabolism, PI3K/AKT/MTOR, EMT, DNA repair, TGF beta, P53 and inflammatory response (NES: 1.7-3.8, all FDR<0.25). SCD1-H had higher frequency of PIK3CA (18.1% vs 8.8%), PTEN (10.7% vs 5.2%), PIK3R1 (6.4% vs 2.3%), AKT1 (3.3% vs 1.3%) and NF1 (8.3% vs 2.7%) mutation compared to SCD1-L, all q<0.05. Conclusion: SCD1 high TNBC tumors are associated with immune suppressive TME, FA metabolism, and dysregulated PI3K pathway, positioning SCD1 as a metabolic driver of therapy resistance and immune evasion and support its targeting to enhance chemo-ICI efficacy. SCD1 inhibitor, MTI-301 significantly reduced tumor growth and enhanced effector immune cell infiltration in TNBC murine models with combinatorial activity with chemo-ICI, indicating that pharmacologic modulation of SCD1 is a promising strategy for cancer therapy. We will be conducting Phase I clinical trial with MTI-301 in pts with advanced tumors including TNBC (NCT NCT06911008). Citation Format: P. P. Advani, S. K. Deshmukh, R. Whetten, M. Redig, M. Pawlush, S. Wu, J. Xiu, J. P. Leone, S. Gandhi, M. Lustberg, G. Sledge Jr, J. Copland. Metabolic and immune reprogramming via SCD1 inhibition enhances chemo-immunotherapy response in TNBC [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS2-12-07.

Abstract Lung cancer is the leading cause of cancer-related deaths worldwide, and despite advances in treatment, immune suppression remains an obstacle to effective therapy. Effector CD4+ T cells (CD4+ Teff) are critical for antitumor immunity, but their function is often inhibited by regulatory T cells (Treg), which accumulate in lung tumors and mediate suppressive functions through multiple mechanisms. This suppression leads to tumor progression and poor patient outcomes. However, the mechanisms underlying Treg-mediated suppression are not fully understood. Herein, we identify the extracellular adenosine 5-triphosphate receptor P2RX7 as a key regulator of Treg function in lung tumors. In a murine lung cancer model induced by Lewis lung carcinoma cells, we found that P2RX7 enhanced the suppressive capacity of tumor-infiltrating Tregs, promoting tumor growth. In T cell–specific P2RX7-knockout (P2RX7-KO) mice, reduced Treg infiltration was accompanied by increased CD4+ Teff accumulation and improved tumor control. Treg-specific P2RX7-KO mice exhibited reduced tumor growth, confirming a Treg-intrinsic role of P2RX7. Suppression assays revealed that tumor-infiltrating wild-type Tregs had greater suppressive activity compared with P2RX7-KO Tregs, which failed to inhibit type 1 and follicular helper T–like responses. This was associated with increased tumor-specific IgG production by lung B cells in P2RX7-KO mice. We also observed that wild-type Tregs expressed higher levels of the immunosuppressive molecule CTLA-4 when compared with P2RX7-KO Tregs. Thus, we conclude that P2RX7 expression on Tregs is essential for their suppressive function in lung cancer and targeting P2RX7 may constitute a strategy to improve lung cancer treatment by alleviating Treg-mediated immune suppression.

Abstract Chimeric antigen receptor T (CART) cell therapy has shown unprecedented success in the treatment of hematological malignancies. However, the immunosuppressive tumor microenvironment of both solid and liquid tumors is a major barrier for CART efficacy. Immunosuppressive myeloid cells inhibit CART efficacy. Colony-stimulating factor 1 receptor (CSF1R) promotes macrophage proliferation, survival, and anti-inflammatory response and is upregulated on myeloid cells in many cancers, making CSF1R an appealing therapeutic target. We aimed to test the interactions between CSF1R, myeloid cells, and CART response, and to study CSF1R targeting in the context of CART cell therapy. We utilized CD19-targeted CART cell therapy (CART19) in lymphoma preclinical models and thyroid-stimulating hormone receptor (TSHR)-targeting CART cell therapy (TSHR-CART) in thyroid cancer models. We first measured CSF1R expression on myeloid cells in vitro. Suppressive myeloid cells, polarized from healthy donor monocytes using an anaplastic thyroid cancer (ATC) cell line, 8505c, or mantle cell lymphoma cell line, JeKo-1, significantly upregulate CSF1R (p=0.0002) compared to media control. After polarization, myeloid cells significantly inhibit TSHR-CART and CART19 antigen-specific proliferation compared to freshly isolated monocytes (p=0.012, p<0.01, respectively) indicating that suppressive myeloid cells contribute to CART failure in multiple tumor types. We then performed single cell RNA sequencing on peripheral blood taken at baseline from patients with mantle cell lymphoma treated with CART19. We found a significant increase of CSF1R on monocyte subsets in CART19 non-responders vs responders (padj=0.0037). Next, we determined the impact of CSF1R blockade on CART cell therapy in vivo. Using lymphoma models, B6 mice were engrafted with the luciferase+ CD19+ murine lymphoma cell line TBL-12 (1x106 cells i.v. 1 day after 250 mg/kg cyclophosphamide). Tumor burden was significantly reduced after 7 days of treatment with low dose CART19 (0.5x106 i.v.) + anti-mouse CSF1R antibody (16mg/kg i.p. twice weekly) vs CART19 + IgG control (p=0.0146). We then tested the impact of CSF1R blockade in mice experiencing tumor relapse. After TBL-12 engraftment, mice were treated with anti-mouse CSF1R or IgG control antibody followed two days later with high dose CART19 (1x106 i.v.) to induce remission. Mice were re-challenged with TBL-12 14 days later. Mice treated with anti-mouse CSF1R antibody showed increased tumor control and significantly higher survival (p=0.0416). Using thyroid cancer models, first we identified high macrophage infiltration in biopsy specimens of patients with ATC compared to normal thyroid tissue and benign thyroid tumors through immunohistochemistry (IHC) of patient samples (p<0.01, p<0.0001, respectively). To test if macrophages are associated with CART failure in ATC, NSG mice were subcutaneously engrafted with 1x106 TSHR+ THJ529 tumors, an ATC cell line derived from patient biopsy samples from the Mayo Clinic thyroid cancer biobank, followed by i.v. treatment with 1x107 TSHR-CART or untransduced T cell control (UTD). IHC staining of tumor tissue collected at experimental endpoints revealed a dose-dependent, significant infiltration of human CD3+ T cells into the tumors which inversely correlated with murine F4/80+ myeloid cell and murine YM-1+ M2 macrophage infiltration. This led us to hypothesize that myeloid cell targeting with CSF1R blockade can improve TSHR-CART efficacy. We utilized the same ATC model described above to test CSF1R targeting. When TSHR+ THJ529 tumors reached approximately 100 mm3, mice were randomized by tumor volume and treated with CSF1R inhibitor PLX5622 (600mg/kg) or vehicle control, followed by either UTD or TSHR-CART cells 5x106 i.v. Mice treated with TSHR-CART + PLX5622 showed significantly improved tumor control vs TSHR-CART + vehicle control (p<0.0001) or UTD + PLX5622 (p<0.0001). Together, our results highlight immunosuppressive myeloid cells which express CSF1R as a major cell type limiting CART efficacy in both solid and liquid tumors. We also identified a strategy to overcome myeloid-mediated suppression of CART cells by targeting CSF1R with antibody or small molecule inhibitors.

Abstract The 5-year survival rate for metastatic melanoma (MM) is 35% with rates increasing to ~50% with immune checkpoint blockade (ICB) treatment. Unfortunately, melanoma brain metastases (MBM) develop in nearly half of MM patients and often relapse rapidly following ICB treatment. MBM resistance to ICB can be attributed to tumor-associated macrophages (TAM). Transcriptional profiling of MM revealed that TAMs possess a lipidated phenotype suggesting that aberrant lipogenic processes confer ICB resistance. Stearoyl-CoA desaturase (SCD) is a lipogenic enzyme that is overexpressed in MM and may cause TAM lipidation. SCD serves as an attractive target for inhibition and combination with ICB for treating MBM. We hypothesize that SCD overexpression produces lipid-rich tumor cells that trigger a phenotypic switch towards immunosuppressive lipid-laden macrophages (LL-Mø). Clinical correlation analysis was conducted to assess SCD expression with ICB response. scRNA-seq data of MBM were analyzed to assess TAMs exhibiting lipidated phenotype. Phagocytosis and lipid transfer was assessed via macrophage and melanoma co-culture using time-lapse microscopy. In-silico modeling and LC-MS/MS was performed to assess blood brain barrier (BBB) penetrance of two small molecule inhibitors of SCD (SCDi): MTI-301 and MF-438. Clinical correlation analysis of MM patients revealed high SCD expression associated with decreased survival of patients treated with ICB. scRNA-seq analysis of MBM revealed upregulation of de novo lipogenesis and cholesterol uptake transcripts within TAM populations. Time-lapse co-culture studies reveal rapid lipid accumulation in macrophages. In-silico modeling predicted SCDi BBB penetration and was corroborated by LC-MS/MS. MBM are notoriously difficult to treat due to poor drug penetrance into CNS and unique microenvironment. We demonstrate that macrophages reprogram towards immunosuppressive LL-Mø, which can be exploited for anti-tumor targeting. The potential for SCDi to synergize with ICB in MBM may improve patient outcomes. MTI-301 is approved for first-in-human clinical trial starting end of 2025.