Unique Tumor Research Articles

Biological subgroups in melanoma: A correlation of tumor genomic and transcriptomic analysis with spatial immunophenotyping.

e14667 Background: A prominent challenge advancing immunotherapy is the heterogeneity of resistance mechanisms leading to drug development failure despite efficacy in subgroup of patients. To address these shortcomings, precision medicine platforms aimed at prospectively stratifying patients into treatment groups based on tumor mutational burden (TMB) and tumor inflammation scores by gene expression profiling (GEP) are now being explored. Whether these gene-based variables reflect the true immunologic state of the tumor remains an open question. Here, we sought to evaluate TMB and GEP as markers of intratumoral inflammatory state by single-cell spatial analysis. Methods: Under an IRB approved protocol through the Huntsman Cancer Institute, 25 melanoma tumors with available clinical, WES, and RNAseq data were stained with a multiplex immunofluorescence-based protocol using Opal dye and Leica Bond Rx (CD8, CD68, PD1, PD-L1, Ki67, SOX10, DAPI) and scanned with Akoya Polaris whole slide scanner. Images were analyzed using HALO. Results: Melanoma tumors were stratified into 4 subgroups based on TMB (<10 vs ≥10 m/Mb) by WES, and inflammatory (Inflm) gene signature expression (GSEA >0 vs ≤0) by RNAseq, denoted as S1 (TMBhi/Inflmhi; n=4), S2 (TMBhi/Inflmlo; n=4), S3 (TMBlo/Inflmhi; n=8), and S4 (TMBlo/Inflmlo; n=9). The rate of disease progression was 0% (S1), 25% (S2), 25% (S3), and 56% (S4). Infiltration analysis of CD8 T cells showed elevated intratumoral CD8 density in S1 (249/mm2) and S3 (157/mm2) vs S2 (65/mm2) and S4 (65/mm2; p=0.0002), consistent with GEP findings. Spatial analysis showed a similar pattern of CD8 distribution across subgroups with peak CD8 density in the tumor periphery. Proximity analyses showed average distance of CD8 T cell to the nearest tumor cell was not different across subgroups. Furthermore, we found Inflmhi tumors had a higher frequency of PD1+ CD8 T cells relative to Inflmlo tumors (12.9 vs 2.8 cells/HPF; p=0.0002), suggesting GEP also reflects CD8 activation and functional status. Increased frequency of PD1+ CD8 T cells was correlated with a much improved overall survival (HR=3.3; p=0.017). A similar analysis performed on CD68+ macrophages showed significantly increased peri-tumoral macrophage recruitment in S4 (445/mm2) vs S1 (209/mm2; p<0.0001), S2 (91/mm2; p<0.0001), and S3 (267/mm2; p=0.0003) subgroups. Interestingly, Inflmhi tumors were associated with an increased proportion of PDL1+ macrophages regardless of TMB status (43% vs 3%; p<0.0001), suggestive of an upregulated adaptive immune response in tumors with active inflammation. Conclusions: Our findings illustrate that biological groupings based on TMB and GEP biomarkers correlate with CD8 spatial location and activation state. Each subgroup has unique tumor immune features that can be related to immune resistance and warrant further investigation.

Pan-tumor activity of olomorasib (LY3537982), a second-generation KRAS G12C inhibitor (G12Ci), in patients with KRAS G12C-mutant advanced solid tumors.

3007 Background: Olomorasib is a potent and highly selective second-generation inhibitor of GDP-bound KRAS G12C, which preclinically delivers >90% sustained target occupancy. Here, we report updated results from LOXO-RAS-20001, a phase 1/2 study of olomorasib in patients with KRAS G12C-mutant advanced solid tumors (NCT04956640). Methods: Patients (pts) with advanced solid tumors positive for KRAS G12C (tissue or plasma) were eligible. Dose escalation used a mTPI-2 method, followed by expansion cohorts in NSCLC (with/without prior G12Ci), CRC, and other solid tumors. Safety was evaluated across all pts dosed. Antitumor activity per RECIST v1.1 was studied in all pts who had ≥1 post-baseline response assessment (PBRA) or had discontinued before the first PBRA. Serial ctDNA analysis was performed using FoundationOne Liquid CDx. Results: As of 30 October 2023, 157 pts (58 NSCLC, 32 CRC, 24 PANC, 43 other solid tumors) received single agent olomorasib (50-200 mg BID PO); 29 pts with NSCLC had received a prior KRAS G12Ci. Median age was 65 yrs (range, 36-85), median number of prior systemic therapies was 3 (range, 0-11). Any grade TRAEs were 62%; TRAEs ≥10% were diarrhea (24%), fatigue (10%), and nausea (10%); grade ≥3 TRAEs were 5%. TRAEs led to dose hold in 10% of pts, dose reduction in 3%, and discontinuation in 2%. Among 10 pts treated after discontinuing prior G12Ci due to toxicity (5/10 due to LFT increase), 1 pt (10%) required olomorasib dose reduction and none discontinued due to toxicity. 68 pts are ongoing and 89 discontinued treatment. 146 pts were efficacy evaluable (120 G12Ci-naïve; 26 with prior G12Ci) with a median follow-up of 10 months (95% CI, 7-13). As anticipated, ORR was lower in 32 pts with CRC (9%, 3 PR; DCR 84%)1 and higher in 88 pts with non-CRC tumors (40%, 30 PR and 5 uPR pending/ongoing in 13 unique tumor types; DCR 90%). mPFS ranged across tumor types from 4 months (CRC, 95% CI, 3-7) to 9 months (NSCLC, 95% CI, 3-NE). In the 26 efficacy evaluable NSCLC pts with prior KRAS G12Ci treatment (16 discontinued due to PD, 9 due to AE), the ORR was 39% (9 PR, 1 uPR pending/ongoing; DCR 73%); mPFS was 6 months (95% CI, 3-NE). In 37 pts with ctDNA results at baseline and ongoing, ctDNA response (>50% KRAS G12C VAF reduction) was seen in pts with PR (11/11), SD (17/22), and PD (1/4). Conclusions: Olomorasib demonstrates efficacy across a range of KRAS G12C-mutant solid tumors with a favorable safety profile including in pts with prior G12Ci intolerance. Activity of the second-generation G12Ci olomorasib after prior exposure to G12Ci demonstrates the increased potency and target coverage these agents can deliver compared to first generation inhibitors. Phase 2 expansion is currently enrolling pts with PANC, and a global registrational study investigating olomorasib in combination with pembrolizumab in first-line NSCLC is ongoing (NCT06119581). 1. Hollebecque A. et al. ASCO-GI 2024. Clinical trial information: NCT04956640 .

Epidemiology of Adenosquamous Carcinomas.

Adenosquamous carcinomas (ASCs) are a very rare histology containing cancer cells with both glandular-like (adeno) and squamous cell histologies, comprising typically a fraction of a percent of all solid tumors. The bulk of the literature on ASCs is comprised of case reports and small series, with the general finding that ASCs tend to have worse outcomes than either of their parent histologies. However, there is a lack of pan site-comparative studies in the literature that compare ASC clinicodemographic and survival outcomes with those of conventional adenocarcinomas (ACs) and squamous cell carcinomas (SCCs). In this study, we summarize these outcomes in eight primary sites, comprising 92.7% of all ASC cases diagnosed from 1975 to 2020 in the Surveillance, Epidemiology, and End Results (SEER) database. Lung ASCs comprise 51.5% of all ASC cases, accounting for 1.1% of all lung cancer cases, followed by uterine/cervical cancers at 29.7% of all ASC cases, translating into 1.8% of all cancers in this site. In descending order, the remaining 20% of ASCs arise in pancreatic, oral cavity, biliary, esophageal, colorectal, and gastric sites, comprising between 0.1% and 0.7% of all cancers in these sites. Apart from pancreatic and oral cavity cancers, ASC tumors tended to favor higher rates of regional or distant disease at presentation with poor tumor differentiation compared to either AC or SCC histologies. After multivariable analysis, adjusting for age, sex, detection stage, grade differentiation, surgery, chemotherapy, and radiotherapy, except for oral cavity cancers, ASCs tended to have worse overall survivals compared to ACs (hazard ratios: 1.1 - 1.6) and SCC (1.0 - 1.3), with colorectal ASCs having the worse overall survival compared to colorectal ACs, with a hazard ratio of 1.4 (95% confidence interval: 1.3 - 1.6). Overall, these results suggest that ASC outcomes are site specific, and in general, tend to have worse outcomes than nonvariant ACs and SCCs even after correction for common clinical and epidemiological factors. These cancers have a poorly understood but unique tumor biology that warrants further characterization.

Yolk sac tumor of the liver: Presentation, diagnosis, and treatment review.

e16371 Background: Yolk Sac Tumor of the Liver (YSTL) is an extremely rare extragonadal germ cell tumor with gonadal origin and histology which presents in the liver. While uncommon, this tumor is often misdiagnosed due to the similarities between YSTL, HCC, and Hepatoblastoma (HB). As this cancer can present with serious mortality, our review aimed to evaluate clinical findings, diagnostic workup, and treatments in patients with YSTL. Methods: We performed a literature search in PubMed from 1950 to October 2023 using filters English language and full text with keywords “Yolk sac tumor of the liver”, “Endodermal Sinus tumor of liver”, “Hepatic Yolk sac tumor”, and “Hepatic Endodermal sinus tumor”. We also conducted a combined search query with all these search terms and “primary”. Patients were included in the study if they had primary YSTL and no other malignancy. Results: Our results looked at 19 patients ranging from 15 months to 64 years with median age being 27 years, including 13 female (68%) and 6 male (32%) patients, percentages reflect the total number of patients. The key presenting symptom in adults was abdominal pain (55%), while the key presenting symptom in children was abdominal distention (63%). All patients in the study had a diagnostic workup that included imaging and pathology. Imaging included CT Abdomen (68%) and MRI (37%), in 58% of patients a solitary mass was seen on imaging, while in 42% of patients multiple hepatic masses were seen. Histology workup mainly noted Shiller Duval Bodies(SDBs)(76%). Molecular Markers included AFP(42%), Alpha-1 anti-trypsin(A1AT)(26%), SALL4(21%), Pancytokeratin(PK)(11%), and Placental-like alkaline phosphatase(PALP)(11%). Treatment included chemotherapy(58%), surgery(47%), transplant(11%), and trans-arterial chemoembolization(5%). Out of the 11 patients who were treated with chemotherapy, 91% received the bleomycin, etoposide, and cisplatin (BEP) regimen. The remaining 9 % of patients received a regimen of cisplatin, adriamycin, and pepleomycin. Conclusions: YSTL is a unique tumor presenting in patients of all ages, tending to present vaguely often with abdominal pain or distension. Diagnostic workup often includes abdominal imaging (MRI and CT Abdomen) and pathology with a focus on SDBs on histologic examination and stains like AFP, A1AT, SALL4, etc. Treatment often focuses on surgery and chemotherapy, notably BEP. Though both HCC and HB traditionally present as a multifocal liver mass on imaging along with positive staining for AFP and PK, our study helps differentiate this tumor from others by emphasizing the importance of SDBs in diagnosis and highlighting new molecular markers to help make the diagnosis easier.

Cascade Self-Generation of Carbon Monoxide Triggered by Photoinduced Holes for Efficient Hypoxic Tumors Therapy.

It still remains challenging to design multifunctional therapeutic reagents for effective cancer therapy under a unique tumor microenvironment including insufficient endogenous H2O2 and O2, low pH, and a high concentration of glutathione (GSH). In this work, a CO-based phototherapeutic system triggered by photogenerated holes, which consisted of ionic liquid (IL), the CO prodrug Mn2(CO)10, and iridium(III) porphyrin (IrPor) modified carbonized ZIF-8-doped graphitic carbon nitride nanocomposite (IL/ZCN@Ir(CO)), was designed for cascade hypoxic tumors. Upon light irradiation, the photogenerated holes on IL/ZCN@Ir(CO) oxidize water into H2O2, which subsequently induces Mn2(CO)10 to release CO. Meanwhile, IrPor can convert H2O2 to hydroxyl radical (•OH) and subsequent singlet oxygen (1O2), which further triggers CO release. Moreover, the degraded MnO2 shows activity for glutathione (GSH) depletion and mimics peroxidase, leading to GSH reduction and •OH production in tumors. Thus, this strategy can in situ release high concentrations of CO and reactive oxygen species (ROS) and deplete GSH to efficiently induce cell apoptosis under hypoxic conditions, which has a high inhibiting effect on the growth of tumors, offering an attractive strategy to amplify CO and ROS generation to meet therapeutic requirements in cancer treatment.

Evaluation of Neoplasia, Treatments, and Survival in Lizard Species.

Neoplasia has been reported in lizards, but more research is needed to accurately document the prevalence and prognosis of the various known neoplasms that affect lizards. This study reviewed medical records from an online database, the Exotic Species Cancer Research Alliance (ESCRA), and reviewed published literature to determine the prevalence of neoplasia, malignancy, metastasis, treatment strategies, and outcomes by species and sex. Records from 55 individual lizards, 20 different species, and 37 different tumors were identified. In the literature, 219 lizards, 59 species, and 86 unique tumors were identified from 72 published case reports. Potential signalment factors such as age, sex, and species were evaluated to see if they affected case outcome. Additional factors including neoplasia type, presence of metastasis, and types of pursued treatments were also evaluated. Statistical analysis was performed to determine whether a factor was significantly associated with animal death due to the identified neoplasia or with animal survival or death due to other causes (non-neoplastic outcomes). Komodo dragons and savannah monitors were more likely to die from neoplasia compared to other lizard species. Cases where the status of metastasis was unknown were significantly associated with death due to neoplasia. Having an unknown status of male versus female was significantly associated with non-neoplastic outcomes of death. Leukemia and islet cell carcinoma were significantly associated with death due to neoplastic causes. Chondrosarcoma, myxosarcoma, osteosarcoma, and squamous cell carcinoma were significantly associated with non-neoplastic outcomes of death. Surgery alone and radiation therapy alone each were significantly associated with non-neoplastic outcomes of death, while lizards not receiving treatment were significantly associated with death due to neoplasia. Benign neoplasia was significantly associated with non-neoplastic outcomes of death. These results will aid in the improved diagnosis and management of neoplasia in lizard species, as well as expanding our understanding of prognostic indicators of neoplasia in lizards.

Abstract PO2-14-03: Novel Metrics of HER2 Heterogeneity in HER2-Positive and HER2-Low Breast Cancer via High Dimensional Multiplexed Immunofluorescence Spatial Profiling

Abstract Background: Categorizing breast cancer HER2/ERBB2 expression as “positive” or “negative” is no longer sufficient, with evidence that treatment response and outcomes are associated with HER2 “low” status and HER2 intratumoral heterogeneity. We hypothesized that interrogating HER2 heterogeneity (HER2het) across multiple spatial resolutions would more accurately capture HER2 diversity and be associated with clinical outcomes. Methods: We interrogated tumor cell and microenvironmental features by profiling 1,113,204 single cells in tissue sections from 171 HER2+/HER2low cancers via custom 25-marker high dimensional multiplexed immunofluorescence (HDmIF) using NeoGenomics MultiOmyx, with adjacent section HER2 immunohistochemistry (IHC). We developed novel metrics to concurrently: 1) interrogate HER2 heterogeneity at four spatial resolutions; 2) use machine learning to translate HER2 IF to IHC, termed ‘HAIQu’ (HER2 Automated Immunofluorescence Quantification), scoring HER2 IF expression according to ASCO/CAP guidelines; 3) delineate HER2 signaling phenotypes at the tumor cell level based on six HER2-related proteins; 4) evaluate immunophenotype of 23 immune cell types. We evaluated the association of these novel HER2het metrics with patient clinicopathologic features, recurrence-free survival (RFS), overall survival (OS), and diverse antibody markers representing tumor cell intrinsic processes and tumor-immune microenvironment (TME). Results: 1166 regions of interest were analyzed from 208 unique tumors profiled. Median follow-up from diagnosis was 143 months and 98.9% (n=183/185) received HER2-directed therapy in the (neo)adjuvant or metastatic setting. Our HAIQu scoring system effectively translated adjacent section HER2 IF to IHC with 97.9% concordance between HAIQu and clinical IHC scoring. Single-cell phenotypic analyses of 392,984 HER2+/PanCK+ tumor cells’ concurrent expression of six HER2-positive breast cancer related proteins (HER2, HER3, EGFR, pAKT, ER, KI67) using an unsupervised neural network-based self-organizing map approach resulted in 7 HER2 signaling cell phenotypes. Most patient samples are dominated by a single cell cluster but, intriguingly, Cluster 1 cells (EGFR-low) predominate in tumors with high HER2 cell membrane heterogeneity (ANOVA p=0.003). Evaluation of immunophenotype in hormone receptor-negative, HER2+ tumors, demonstrated significant association with immune cluster and recurrence-free survival (RFS; log-rank p=0.024) with zero RFS events among immune-high versus median survival of only 53.5mo among immune low-PDL1 low tumors. A multivariable Cox proportional hazards model including single cell HER2-heterogeneity (only significant metric on univariate), receptor subtype, and immunophenotype cluster demonstrated significant association with RFS (overall model log-rank p=0.005) and each significantly contributed to the model (all p< 0.05). Conclusions: We present novel metrics of HER2 heterogeneity via HDmIF, which offer detailed characterization of the diversity of HER2 expression in a large, clinically-annotated cohort with long-term follow-up. Identification of a strong association between immunophenotype and RFS supports further investigation of the highly immune activated subsets of ER-/HER2+ breast cancer. Strong correspondence of HER2 IF and IHC and our HAIQu methodology offers a pathway to translation of HER2het metrics to clinical practice. Table 1. Association of HER2 Heterogeneity Metrics with Recurrence-Free Survival Citation Format: David Tallman, Anna Juncker-Jensen, Harry Nunns, Kevin Gallagher, Heather LeFebvre, Karen Yamamoto, Katharine Collier, Mark Vater, Ava Strahan, Mathew Cherian, Ashley Pariser, Preeti Sudheendra, Bhuvaneswari Ramaswamy, Margaret Gatti-Mays, Ainura Kyshtoobayeva, Zaibo Li, Daniel Stover, Kai Johnson. Novel Metrics of HER2 Heterogeneity in HER2-Positive and HER2-Low Breast Cancer via High Dimensional Multiplexed Immunofluorescence Spatial Profiling [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-14-03.

Abstract PS10-04: The Landscape of Somatic Genetic Alterations in Breast Cancers from Carriers of Germline Pathogenic Variants in DNA-repair Genes

Abstract Background: Hereditary breast cancer in carriers of germline pathogenic or likely pathogenic variants (PVs) in ATM, BRCA1, BRCA2, CHEK2, and PALB2 have unique clinicopathological characteristics compared to sporadic breast cancer. However, very little is known about the underlying differences in somatic genetic alterations between hereditary and sporadic breast cancer. Methods: The study included 7,533 individuals with breast cancer subjected to Tempus xT tumor-normal matched sequencing (596-648 genes). The frequencies of the somatic genetic alterations in each gene were compared separately between tumors arising in individuals with incidental germline PVs (gATM, gBRCA1, gBRCA2, gCHEK2, gPALB2) and sporadic breast tumors. Sporadic tumors were identified as individuals with no detected incidental germline PVs in these 5 genes. Comparisons were made by either Pearson’s Chi-squared or Fisher’s exact test, with false discovery rate (FDR) correction for multiple testing. Breast cancer subtype was determined based on the record of IHC positivity for ER, PR, or HER2. Detection of ERBB2 (HER2) gene amplifications via DNA sequencing was also used to classify samples as HER2+ in the absence of available IHC data. Results: The median age at breast cancer diagnosis for the cohort was 56 years. More than two-thirds of the patients were White (73%) while 14% identified as Black or African American. The overall frequency of incidental germline PVs in each gene was 0.8% for gATM, 1.4% for gBRCA1, 2.1% for gBRCA2, 1.0% for CHEK2, and 0.7% for PALB2. A total of 3,648 (48.4%) tumors were ER+/PR+/HER2-, 1,297 (17.2%) were triple-negative (TNBC), 841 (11.2%) were HER2+ and 1,747 (23.2%) could not be classified due to missing ER, PR or HER2 status, or absence of detected ERBB2 amplifications. Among ER+/PR+/HER2- breast cancers, compared to sporadic tumors, ESR1 mutations were significantly enriched in gATM carriers (33% vs. 11%, q-value 0.05), TP53 alterations were significantly enriched in gBRCA1 PV carriers (69% vs. 30%, q-value < 0.001) but depleted in gATM (12% vs. 30%, q-value 0.4) and gCHEK2 PV carriers (5.4% vs. 30%, q-value 0.06), and PIK3CA (14% vs. 35%, q-value 0.001) and CCND1 (3.4% vs. 17%, q-value 0.02) alterations were significantly lower in gBRCA2 PV carriers. Among TNBC, TP53 alterations were also significantly higher in gBRCA1 PV carriers compared to sporadic tumors (96% vs. 69%, q-value 0.004). In HER2+ breast cancers, ERBB2 alterations were observed in approximately two-thirds of the tumors, and a significant difference was not observed between incidental hereditary and sporadic tumors. Among ER+/PR+/HER2- tumors, although not statistically significant, the frequency of ESR1 (3.1% vs. 11%, q-value >0.9), PIK3CA (12% vs. 35%, q-value 0.2) alterations were lower in incidental gBRCA1 versus sporadic tumors, FGFR1 alterations were lower in incidental gBRCA1 (6.2% vs. 13%, q-value >0.9) and incidental gBRCA2 (3.4% vs. 13%, q-value 0.13) but enriched in incidental gATM (33% vs. 13%, q-value 0.05). Conclusions: The observed differences in the frequencies of CCND1, ESR1, PIK3CA, TP53, and other key genetic alterations between incidental hereditary and sporadic breast cancer highlight the unique tumor biology of breast cancer in germline PV carriers and have significant implications for understanding tumorigenesis and identifying therapeutic strategies for the management of hereditary breast cancer. Citation Format: Minxuan Huang, Melissa Stoppler. The Landscape of Somatic Genetic Alterations in Breast Cancers from Carriers of Germline Pathogenic Variants in DNA-repair Genes [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS10-04.

Keratinocytes Present Staphylococcus aureus Enterotoxins and Promote Malignant and Nonmalignant T Cell Proliferation in Cutaneous T-Cell Lymphoma

Cutaneous T-cell lymphoma is characterized by malignant T cells proliferating in a unique tumor microenvironment dominated by keratinocytes (KCs). Skin colonization and infection by Staphylococcus aureus are a common cause of morbidity and are suspected of fueling disease activity. In this study, we show that expression of HLA-DRs, high-affinity receptors for staphylococcal enterotoxins (SEs), by KCs correlates with IFN-γ expression in the tumor microenvironment. Importantly, IFN-γ induces HLA-DR, SE binding, and SE presentation by KCs to malignant T cells from patients with Sézary syndrome and malignant and nonmalignant T-cell lines derived from patients with Sézary syndrome and mycosis fungoides. Likewise, preincubation of KCs with supernatant from patient-derived SE-producing S aureus triggers proliferation in malignant T cells and cytokine release (including IL-2), when cultured with nonmalignant T cells. This is inhibited by pretreatment with engineered bacteriophage S aureus-specific endolysins. Furthermore, alteration in the HLA-DR-binding sites of SE type A and small interfering RNA-mediated knockdown of Jak3 and IL-2Rγ block induction of malignant T-cell proliferation. In conclusion, we show that upon exposure to patient-derived S aureus and SE, KCs stimulate IL-2Rγ/Jak3-dependent proliferation of malignant and nonmalignant T cells in an environment with nonmalignant T cells. These findings suggest that KCs in the tumor microenvironment play a key role in S aureus-mediated disease activity in cutaneous T-cell lymphoma.

The S100 family is a prognostic biomarker and correlated with immune cell infiltration in pan-cancer

BackgroundThe S100 protein family is a group of small molecular EF-hand calcium-binding proteins that play critical roles in various biological processes, including promotion of growth, metastasis and immune evasion of tumor. However, the potential roles of S100 protein family expression in tumor microenvironment (TME) cell infiltration in pan-cancer remain elusive.MethodsHerein, we conducted a comprehensive assessment of the expression patterns of the S100 protein family in pan-cancer, meticulously examining their correlation with characteristics of TME cell infiltration. The S100 score was constructed to quantify S100 family expression patterns of individual tumors.ResultsThe S100 family was a potent risk factor in many cancers. Clustering analysis based on the transcriptome patterns of S100 protein family identified two cancer clusters with distinct immunophenotypes and clinical characteristics. Cluster A, with lower S100 expression, exhibited lower immune infiltration, whereas, Cluster B, with higher S100 expression, featured higher immune infiltration. Interestingly, Cluster B had a poorer prognosis, likely due to an immune-excluded phenotype resulting from stromal activation. The analysis revealed robust enrichment of the TGFb and EMT pathways in the cohort exhibiting high S100 score, alongside a positive correlation between the S100 score and Treg levels, suggesting the manifestation of an immune-excluded phenotype in this group. Moreover, S100 families were associated with the prognosis of 22 different cancers and a noteworthy association was observed between high S100 score and an unfavorable response to anti-PD-1/L1 immunotherapy. Consistent findings across two independent immunotherapy cohorts substantiated the advantageous therapeutic outcomes and clinical benefits in patients displaying lower S100score.ConclusionOur analysis demonstrated the role of S100 family in formation of TME diversity and complexity, enabling deeper cognition of TME infiltration characterization and the development of personalized immunotherapy strategies targeting S100 family for unique tumor types.

Innovative tumor interstitial fluid-triggered carbon dot-docetaxel nanoassemblies for targeted drug delivery and imaging of HER2-positive breast cancer

In this study, we have developed an innovative pH-triggered nanomedicine delivery system, targeting HER2-positive breast cancer cells for effective low-cost, imaging-guided drug delivery and precise therapy. The key feature of this system lies in its unique tumor interstitial fluid microenvironment-responsive drug release behavior which achieved tumor site-specific drug delivery. Our in vitro experiments demonstrated that the carbon dot-integrated material achieves more efficient DTX release (96.13 % at 72 h) in the tumor interstitial fluid microenvironment (pH 6.5), thereby boosting drug concentration at the tumor site and enhancing therapeutic efficacy. Further cell experiments confirmed the system's significant inhibitory effect on HER2-positive tumor cells SKBR3 in a pH 6.5 environment, and apoptosis assays indicating a notable increase in early cell apoptosis (from 8.39 % to 24.61 % compared with pH 7.4). Furthermore, the integration of HER2 aptamer within the carbon dot-based system enables targeted recognition and binding to tumor cells, ensuring more precise delivery of DTX while minimizing potential side effects. Crucially, the carbon dots in this system emit superior red fluorescence (the QY = 47.64 % excited at 535 nm compared with Rodamine 6G), enabling real-time visualization of the drug delivery process. This feature provides valuable feedback on treatment effectiveness, facilitating necessary adjustments. The small size (1.88 ± 0.48 nm) of carbon dots significantly improved their ability to penetrate biological barriers, while their low toxicity (no significant cell toxicity under 350 μg/mL) contributed to the formulation’s outstanding biocompatibility. Overall, this carbon dot-enhanced drug delivery system offers immense potential for enhancing drug efficacy, minimizing side effects, and providing real-time treatment monitoring, thus proposing a innovate strategy for breast cancer therapy.

Senescence Defines a Distinct Subset of Myofibroblasts That Orchestrates Immunosuppression in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) therapeutic resistance is largely attributed to a unique tumor microenvironment embedded with an abundance of cancer-associated fibroblasts (CAF). Distinct CAF populations were recently identified, but the phenotypic drivers and specific impact of CAF heterogeneity remain unclear. In this study, we identify a subpopulation of senescent myofibroblastic CAFs (SenCAF) in mouse and human PDAC. These SenCAFs are a phenotypically distinct subset of myofibroblastic CAFs that localize near tumor ducts and accumulate with PDAC progression. To assess the impact of endogenous SenCAFs in PDAC, we used an LSL-KRASG12D;p53flox;p48-CRE;INK-ATTAC (KPPC-IA) mouse model of spontaneous PDAC with inducible senescent cell depletion. Depletion of senescent stromal cells in genetic and pharmacologic PDAC models relieved immune suppression by macrophages, delayed tumor progression, and increased responsiveness to chemotherapy. Collectively, our findings demonstrate that SenCAFs promote PDAC progression and immune cell dysfunction. Significance: CAF heterogeneity in PDAC remains poorly understood. In this study, we identify a novel subpopulation of senescent CAFs that promotes PDAC progression and immunosuppression. Targeting CAF senescence in combination therapies could increase tumor vulnerability to chemo or immunotherapy. See related article by Ye et al., p. 1302.

Tumor metabolism in pheochromocytomas: clinical and therapeutic implications.

Pheochromocytomas and paragangliomas (PPGLs) have emerged as one of the most common endocrine tumors. It epitomizes fascinating crossroads of genetic, metabolic, and endocrine oncology, providing a canvas to explore the molecular intricacies of tumor biology. Predominantly rooted in the aberration of metabolic pathways, particularly the Krebs cycle and related enzymatic functionalities, PPGLs manifest an intriguing metabolic profile, highlighting elevated levels of oncometabolites like succinate and fumarate, and furthering cellular malignancy and genomic instability. This comprehensive review aims to delineate the multifaceted aspects of tumor metabolism in PPGLs, encapsulating genetic factors, oncometabolites, and potential therapeutic avenues, thereby providing a cohesive understanding of metabolic disturbances and their ramifications in tumorigenesis and disease progression. Initial investigations into PPGLs metabolomics unveiled a stark correlation between specific genetic mutations, notably in the succinate dehydrogenase complex (SDHx) genes, and the accumulation of oncometabolites, establishing a pivotal role in epigenetic alterations and hypoxia-inducible pathways. By scrutinizing voluminous metabolic studies and exploiting technologies, novel insights into the metabolic and genetic aspects of PPGLs are perpetually being gathered elucidating complex interactions and molecular machinations. Additionally, the exploration of therapeutic strategies targeting metabolic abnormalities has burgeoned harboring potential for innovative and efficacious treatment modalities. This review encapsulates the profound metabolic complexities of PPGLs, aiming to foster an enriched understanding and pave the way for future investigations and therapeutic innovations in managing these metabolically unique tumors.

Abstract LB125: Tri-specific T cell engager targeting of selective surface cancer-selective ligands recruits both T cells and APC targeting of cancer neoantigens of tumor-initiating stem-like cells

Abstract Chemotherapy does not sufficiently eliminate tumor-initiating cells (TICs) of hepatocellular carcinoma (HCC). To remove TICs and achieve personalized cancer therapy, dendritic cells (DC) were vaccinated against tumor germline mutations, but metastatic cancers recurred in many cases. Emerging data suggest that nanoparticle-based siRNA delivered targeting of stemness transcription factor NANOG (pluripotency transcription factor) potentiates anti-tumor immunity. We hypothesized that pre-treatment of selective TIC inhibitors targeting stemness genes sensitized the efficacy of immunotherapy targeting of liver TICs. Novel TIC-targeting immunoglobulin, variable chain fragments were identified by phage-display library screening. The top single chain camelid antibody (scFv) candidates were identified and individually cloned into mammalian expression vectors to test binding to TICs. A Tri-specific T cell engager (TriTE) was constructed to connect TIC-targeting scFv with anti-dendritic cell (DC) scFv (anti-CD14) and CD3. Such scFv vectors were tested for target cell lysis. Candidate ligands of anti-TIC ScFvs present on the tumor cell surface were identified through a series of bioinformatic analysis., The latter provided the preconditions for one of our aims to identify the target, tumor surface ligand(s) of anti-TIC ScFv to better understand the mechanism of TriTE action upon a tumor cell. IP-Mass spectrometry analyses demonstrated that two target surface antigens, TBCE and CEP170, along with their respective mRNAs were highly expressed in CD133+ TIC Huh7 cells when compared to CD133- non-TIC Huh7 cells. This accounted for specific TriTE binding to TIC cells, but not to CD133(-) Huh7 cells or primary hepatocytes. These data demonstrated that these unique tumor antigens, primarily arising during neoplastic transformation, elicited T and/or monocyte immunity capable of protecting the host from cancer progression. These conjunctive with PD1 antibody therapeutic modality leads to the personalized immune/chemotherapy of HCC patients. Human monocyte-derived DCs, TIC and T cells were incubated with TriTE to measure IFNγ production during CTL killing effects against TICs. TriTE treatment significantly reduced tumor growth of PDX tissues in NSG-SG3 mice with humanized immunity. Other novel surface antigens on TIC were identified by mass spectroscopy analyses. These data demonstrated that the presence of unique tumor antigens, primarily arising during neoplastic transformation, which elicited T and/or myeloid cell immunity capable of protecting the host from cancer progression. Self-adapting antigen-targeting machinery with Trite therapy is adaptable and fine-tuning next-generation immunotherapy. Citation Format: Wei Ma, Nuan Wang, Hye Yeon Choi, Lin Ziying, Nicolette Fajardo, Royce Ilaga, Risa Machida, Zhou Lin, Ambika Ramrakhiani, Yvonne Y. Chen, Linda Sher, Stanley M. Tahara, Keigo Machida. Tri-specific T cell engager targeting of selective surface cancer-selective ligands recruits both T cells and APC targeting of cancer neoantigens of tumor-initiating stem-like cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB125.

Solid pseudopapillary neoplasm of the pancreas during pregnancy presenting as gastrointestinal stromal tumor: A case report and review of literature

Solid pseudopapillary neoplasm (SPN) is a rare tumor that can complicate pregnancy. More than its rarity, SPNs are unique neoplasms because of their obscure histogenesis, cytology, immunohistochemical profile, and imaging characteristics. This report describes the case of a 32-year-old gravida 2 para 1 (1001) seen at 24 weeks with an intra-abdominal mass. The patient presented with a long-standing history of abdominal mass with the working impression of gastrointestinal stromal tumor. We employed a multidisciplinary approach to closely monitor tumor growth, ensure maternal and fetal well-being, avert complications, and avoid unnecessary clinical interventions. Histopathological evaluation and immunohistochemistry studies of representative specimens taken at the time of delivery revealed the diagnosis of SPN of the pancreas. Based on a review of local search engine databases, this is the first documented case of SPN complicating pregnancy in the Philippines.

Metabolome Profiling of Malignant Ascites Identifies Candidate Metabolic Biomarkers of Hepatocellular Carcinoma.

Malignant ascites is one of the severe complications of hepatocellular carcinoma, which can be regarded as a unique tumor microenvironment of hepatocellular carcinoma. The identification of novel biomarkers in malignant ascites could be crucial to differentiate patients with hepatocellular carcinoma and cirrhotic ascites. The study aimed to distinguish the metabolomics of malignant ascites in patients with hepatocellular carcinoma from that of non-malignant ascites (cirrhotic ascites). Liquid chromatography-mass spectrometry was performed to analyze the differentially distributed biomarkers in patients with malignant ascites and hepatocellular carcinoma (n = 39), as well as in patients with cirrhotic ascites, which were taken as controls (n = 36). A total of 20 differential metabolites associated with malignant ascites were identified, of which 8 metabolites were upregulated and 12 metabolites were downregulated (ratio < 0.5 or > 1.5, respectively). Moreover, pathway and enrichment analyses revealed nitrogen metabolism, urea cycle, phenylalanine, and tyrosine metabolism to be implicated in the formation of malignant ascites in patients with hepatocellular carcinoma. Our results suggest that the key factors associated with pathways, such as arachidonic acid, phenylalanine, and glutamic acid pathways, are potential ascitic fluidbased biomarkers for differentiating hepatocellular carcinoma with cirrhosis ascites; the results also provide a clinical pathophysiological interpretation of biomarkers and metabolic pathways relevant to disease status.

Abstract 3996: Secreted cytokine-αPDL1 fusion proteins improve solid tumor chimeric antigen receptor (CAR) T-cell therapy

Abstract Background: Success of Chimeric Antigen Receptor (CAR) T cells therapy for solid tumors are limited by the suppressive solid tumor microenvironment (TME), T cell exhaustion, lack of persistence, and poor trafficking to tumors. Strategies to improve this include therapeutic combinations, such as checkpoint inhibition (CPI) or cytokine support. However, CPI therapy has largely failed because of refractory and resistant tumors and cytokine administration can lead to lethal toxicities. To this end, we propose that enabling CAR T cells to secrete bi-functional fusion proteins consisting of cytokine modifiers (ie: IL12, IL15, or TGFβ-trap) combined with checkpoint inhibition (αPDL1 scFv) can provide tumor PDL1 sequestered cytokine activity and local tumor-immune modulation to boost solid tumor CAR T cell efficacy, enhance CPI impacts, and safely improve durable outcomes. Methods: Mouse T cells dual transduced to express surface CAR targeting prostate or ovarian solid tumors in addition to secretable cytokine fused to an αPDL1 scFv were generated. In vitro, the PDL1 blockade capacity and tumor-surface cytokine presentation of supernatants from dual transduced CAR T cells was assessed on PDL1 induced tumor cells. Further, secreted fusion protein transduced CAR T cells were assessed for function, phenotype, and cytokine release in a repetitive tumor rechallenge assay. In vivo, mouse CAR T cells dual transduced with fusion proteins and appropriate controls were assessed for anti-tumor efficacy, survival kinetics, and toxicity in immunocompetent solid tumor mouse models of prostate cancer and intraperitoneal disseminated ovarian cancer. Results: CAR T cells were shown to be successfully dual transduced, and secreted αPDL1-cytokine fusion proteins exhibiting functional PDL1 binding characteristics in vitro. CAR T cells engineered with αPDL1-IL12 fusion protein had greater anti-tumor activity and CAR specific expansion compared to other tested fusion proteins in in vitro co-culture assays. In a syngeneic prostate tumor model, mice receiving CAR T cells with αPDL1-IL12 fusion T cells out competed other cytokine fusion combinations. In a syngeneic ovarian tumor model we safely achieved 100% curative response rate with CAR secreting αPDL1-IL12 fusion in contrast to CAR with αPDL1mutIL12 control along with tumor regional PDL1 blockade on myeloid subsets within the TME. Conclusions: Our findings suggest that CAR T cells engineered to secrete αPD-L1-IL12 fusion protein show improved tumor control, less systemic toxicity, and enhanced expansion which promotes eradication of disease in two independent in vivo tumor models with two unique solid tumor CAR targets. We believe this strategy has the potential to improve solid tumor CAR T-cell efficacy and enhance durable innate immune responses. Citation Format: Lea Christian, John P. Murad, Lupita Lopez, Anthony Park, Jason Yang, Eric Lee, Candi Trac, Stephen Forman, Saul J. Priceman. Secreted cytokine-αPDL1 fusion proteins improve solid tumor chimeric antigen receptor (CAR) T-cell therapy [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 3996.

Abstract 2487: KRAS and TP53 co-mutation predicts benefit of immune checkpoint blockade in lung adenocarcinoma

Abstract PD-L1 protein expression is the most important predictive biomarker for immune checkpoint inhibition (ICI) in advanced non-small cell lung cancer (NSCLC), but has limited sensitivity and specificity. We analyzed the potential of activating KRAS and pathogenic TP53 mutations to provide additional predictive information. The study cohort included 713 consecutive immunotherapy patients with advanced lung adenocarcinomas of the Thoraxklinik Heidelberg who were negative for actionable EGFR and ALK/RET/ROS1 alterations. Two external cohorts of patients treated with immunotherapy (SU2C-ICI: n=247, MSK-ICI: n=135) and two external cohorts of surgical early stage patients were additionally analyzed (TCGA-LUAD: n=417, MSK-LUAD: n=394). Therapy benefit was assessed stratified by KRAS and TP53 mutations. RNA-Seq data of TCGA were analyzed to reveal the molecular characteristics of KRASmut/TP53mut tumors. Analyzing overall survival, an interaction between KRAS and TP53 mutations was observed in univariate and multivariate analyses (HR=0.56, p=0.0044 and HR=0.53, p=0.0021). KRASmut/TP53muts tumors performed better than tumors not harboring the dual mutation configuration (HR=0.71, CI 0.55-0.92). This observation could be confirmed in the external cohorts of immunotherapy patients (SU2C-ICI: HR=0.54, CI 0.28-1.03 and MSK-ICI: HR=0.35, CI 0.14-0.88), whereas KRASmut/TP53mut was not associated with prolonged survival in the surgical cohorts. Tumor mutational burden, proliferation (measured by TOP2A mRNA expression), and PD-L1 mRNA were significantly higher in TP53mut compared with TP53wt tumors, regardless of KRAS status. Genome-wide mRNA expression analysis revealed 64 genes including the chemokine CX3CL1 (fractalkine) as specific transcriptomic characteristic of KRASmut/TP53mut tumors. In summary, KRAS/TP53 co-mutation predicts ICI benefit in univariate and multivariate survival analyses and is associated with unique molecular tumor features. Further validation studies are warranted. Mutation testing of the two genes can be easily implemented using small gene panels or even single gene analyses. Citation Format: Jan Budczies, Eva Romanovsky, Martina Kirchner, Olaf Neumann, Miriam Blasi, Johannes Schnorbach, Rajiv Shah, Farastuk Bozorgmehr, Rajkumar Savai, Thorsten Stiewe, Solange Peters, Peter Schirmacher, Thomas Michael, Daniel Kazdal, Petros Christopoulos, Albrecht Stenzinger. KRAS and TP53 co-mutation predicts benefit of immune checkpoint blockade in lung adenocarcinoma [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 2487.

Abstract 3890: Comprehensive molecular and immunological characterization of early-onset esophagogastric cancer

Abstract Background: The incidence of early-onset esophagogastric cancer (EOEGC), defined as age of diagnosis &amp;lt;50, has increased in recent decades. Compared to average-onset esophagogastric cancer (AOEGC), EOEGC are more likely to be genomically stable, have diffuse histology, and present with more advanced disease. Here, we utilized a large real-world data cohort to characterize EOEGC with molecular and immune signatures. Methods: 5,175 esophagogastric cancer (EGC) samples (&amp;lt;50 yrs, n=530; ≥50 yrs, n=4645) were tested by next generation sequencing (NGS) (592, NextSeq; WES, NovaSeq) and whole transcriptome sequencing (WTS) (NovaSeq) (Caris Life Sciences, Phoenix, AZ). EGC patients with age &amp;lt;50 and ≥50 were classified as EOEGC and AOEGC, respectively. Deficient mismatch repair (dMMR)/microsatellite-instability (MSI) was tested by IHC and NGS. Tumor mutational burden (TMB) totaled somatic mutations per tumor (high&amp;gt;10 mt/MB). Pathway enrichment determined by Gene Set Enrichment Analysis (Broad Institute, Cambridge, MA). Immune cell fractions were calculated by deconvolution of WTS: Quantiseq. Statistical significance was determined using chi-square and Mann-Whitney U test with p-values adjusted for multiple comparisons (q &amp;lt; 0.05). Results: EOEGC had higher frequency of CDH1 (18.9% vs 6.5%) but lower frequency of TP53 (65.9% vs 74.4%) mutations compared to AOEGC (all q&amp;lt;0.05). EOEGC had higher frequency of CCNE1 (6.8% vs 4.4%), MYC (6.1% vs 4.1%) and FGFR2 (3.45% vs 1.87%) copy number alterations and ARHGAP26 (5.67% vs 2.2%) fusion. EOEGC had lower frequency of TMB high (3.8 vs 10.1%) and dMMR/MSI-H (1.3% vs 5.7%) (all p&amp;lt;0.05). EOEGC had pathway enrichment of epithelial mesenchymal transition (EMT) (NES: 1.8, FDR: 0.0) and angiogenesis (NES: 1.3, FDR: 0.24). EOEGC had lower median MAPK pathway activity score (MPAS) (-0.16 vs 0.13, p&amp;lt;0.05). Analysis of inferred immune cell infiltrates showed that EOEGC had increased infiltration of B cells (4.7% vs 3.9%) and M2 macrophages (3.6% vs 3%) but decreased infiltration of M1 macrophages (3.7% vs 4%) (all q&amp;lt;0.05). EOEGC had increased T cell inflamed signature (31.3% vs 26.1%, p&amp;lt;0.05) and increased expression of HAVCR2 (TIM3) but decreased expression of FOXP3 and CD274 (PD-L1) (FC: 0.84-1.09, all p&amp;lt;0.05). There was no difference in LAG3, CTLA4, and IDO1 gene expression. Conclusion: EOEGC has several unique molecular and tumor immune microenvironment features. In this real world cohort, EOEGC has increased frequency of CDH1 mutations, ARHGAP26 fusions, enrichment of EMT and angiogenesis pathways, decreased MAPK pathway activity, decreased frequency of TMB high and dMMR/MSI-H, and a unique immune cell infiltrate with decreased M1 macrophages and increased M2 macrophages. These unique differential characteristics present therapeutic opportunities but also demonstrate the limitations of currently approved therapies in this subset of patients. Citation Format: Lawrence W. Wu, Sachin K. Deshmukh, Sharon Wu, Joanne Xiu, Alex Farrell, Vincent Lam, Emil Lou, Sanjay Goel, Chadi Nabhan, Ryan H. Moy. Comprehensive molecular and immunological characterization of early-onset esophagogastric 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 3890.

Abstract 5260: Combination activity of eribulin liposomal formulation and anti-PD-1 antibody after tumor regrowth during anti-PD-1 antibody treatment in mice

Abstract Eribulin (ERI) has been reported a microtubule dynamics inhibitor with unique tumor microenvironment modulations such as vascular remodeling activity. In the previous meeting (AACR2022, 2023), we reported that ERI and liposomal formulation of ERI (ERI-LF) also have immunomodulatory activity that induces CD8+ T cells via its vascular remodeling activity and ERI-LF showed more potent immune modulation and combination activities with anti-PD-1 antibody (PD-1 Ab) than ERI in syngeneic mice models and humanized mice models. Although immune-checkpoint inhibitors (ICI) are using as a key drug for various types of cancers in clinical setting, several clinical questions regarding suitable therapies after ICI therapy and efficacy of ICI rechallenge are remaining. In this study, we evaluated anti-tumor activities of combination of ERI-LF and PD-1 Ab in two syngeneic transplantation models using mouse non-small lung cancer cells, P-glycoprotein-knockout (Pgp-KO) KLN205 cells and Pgp-KO LL2 cells. As a result, combination of 1mg/kg ERI-LF (Q7D×2) with PD-1 Ab (200 ug/head, twice a week ×2 weeks) showed significant stronger antitumor activity compared with each monotherapy in only Pgp-KO KLN205 model, in which ERI-LF increased intratumoral microvascular density as a vascular remodeling activity, not in Pgp-KO LL2 model. We next conducted continuous treatment of PD-1 Ab in Pgp-KO KLN205 model to investigate tumor regrowth during treatment of PD-1 Ab. In this model, tumor growth was inhibited by PD-1 Ab until about two weeks after initiation of the treatment and then this inhibitory activity disappeared after two weeks even by continuous treatment of PD-1 Ab. We performed flow cytometry analysis (FCM) for tumor-infiltrating immune cells and RNAseq analysis using regrowing tumors compared with non-treatment tumors. Expressions of mRNA of several immune inhibitory receptors were upregulated in tumors with regrowth, although CD4+ cells and CD8+ cells were also increased in FCM using tumor samples. Furthermore, we investigated anti-tumor activity of combination of ERI-LF and PD-1 Ab against tumors which changed from inhibitory phase to regrowth phase during PD-1 Ab treatment in Pgp-KO KLN205 model. The combination of ERI-LF at 1mg/kg (Q7D×3) and PD-1 Ab (200 ug/head, twice a week ×3 weeks) also showed potent anti-tumor activity against tumors with regrowth by prior PD-1 Ab treatment as well as PD-1 Ab-naïve tumor, suggesting that this combination therapy might be effective after prior ICI therapy. Currently, Phase 1b/2 clinical trial of ERI-LF plus nivolumab in patients with selected solid cancers (NCT04078295) is underway. Patients with or without prior ICI therapy were enrolled in a small cell lung cancer cohort of this clinical study. Our preclinical results might provide a scientific rationale for a uniqueness of ERI-LF as a post ICI therapy. Citation Format: Moe Tamura, Yuki Niwa, Taro Semba. Combination activity of eribulin liposomal formulation and anti-PD-1 antibody after tumor regrowth during anti-PD-1 antibody treatment in mice [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 5260.