Charting roadmaps towards novel and safe synergistic immunotherapy combinations

CXCL8 may serve as a potential biomarker for predicting the prognosis and immune response in cervical cancer

OBJECTIVE

To investigate the prognostic significance of CXCL8 in cervical cancer and its effect on immune response based on bioinformatics method.

METHODS

This study employs the HPA database to investigate CXCL8 expression in normal human tissues.The TIMER2.0 database is utilized to analyze CXCL8 expression across various types of cancer.Utilizing the TCGA database, we analyze the correlation between CXCL8 and the overall survival (OS) and progression-free interval (PFI) of patients with various tumors using R 4.3.2.Additionally, its association with immune checkpoint-related genes across various types of cancer is examined.We further analyze the association between CXCL8 expression and the expression of LAG3, CTLA4, PDCD1, and CD274 in cervical cancer.The TIMER database is used to study the association between CXCL8 and the extent of Tumor-Infiltrating Immune Cells (TIICs) infiltration.Enrichment analysis of genes related to CXCL8 is conducted using the LinkedOmics database.

RESULT

CXCL8 is found in a wide range of normal human tissues.In the majority of tumor tissues, CXCL8 expression is elevated compared to their normal counterparts.There is a significant correlation between CXCL8 expression and the overall survival (OS) and progression-free interval (PFI) of patients with various tumors.CXCL8 expression is associated with the expression of diverse immune checkpoint-related genes and the extent of Tumor-Infiltrating Immune Cells (TIICs) infiltration.Genes related to CXCL8 participate in diverse immune-related processes in cervical cancer.

CONCLUSION

CXCL8 plays a role in modulating immune infiltration, thereby influencing the prognosis of patients with various tumors, particularly those with cervical cancer.CXCL8 could potentially act as a biomarker for forecasting the prognosis and immune response of patients with tumors.

Five latent factors underlie response to immunotherapy

Only a subset of patients treated with immune checkpoint inhibitors (CPIs) respond to the treatment, and distinguishing responders from non-responders is a major challenge. Many proposed biomarkers of CPI response and survival probably represent alternative measurements of the same aspects of the tumor, its microenvironment or the host. Thus, we currently ignore how many truly independent biomarkers there are. With an unbiased analysis of genomics, transcriptomics and clinical data of a cohort of patients with metastatic tumors (n = 479), we discovered five orthogonal latent factors: tumor mutation burden, T cell effective infiltration, transforming growth factor-beta activity in the microenvironment, prior treatment and tumor proliferative potential. Their association with CPI response and survival was observed across all tumor types and validated across six independent cohorts (n = 1,491). These five latent factors constitute a frame of reference to organize current and future knowledge on biomarkers of CPI response and survival.

Recent advancements of hydrogels in immunotherapy: Breast cancer treatment

Breast cancer is the most prevalent cancer among women and the leading cause of cancer-related deaths in this population. Recent advances in Immunotherapy, or combined immunotherapy, offering a more targeted and less toxic approach, expand the survival rate of patients more than conventional treatment. Notably, hydrogels, a versatile platform provided promising avenues to combat breast cancer in preclinical studies and extended to clinical practices. With advantages such as the alternation of tumor microenvironment, immunomodulation, targeted delivery of therapeutic agents, and their sustained release at specific sites of interest, hydrogels can potentially be used for the treatment of breast cancer. This review highlights the advantages, mechanisms of action, stimuli-responsiveness properties, and recent advancements of hydrogels for treating breast cancer immunotherapy. Moreover, post-treatment and its clinical translations are discussed in this review. The integration of hydrogels in immunotherapy strategies may pave the way for more effective, personalized, and patient-friendly approaches to combat breast cancer, ultimately contributing to a brighter future for breast cancer patients.

Short-term cultured tumor fragments to study immunotherapy combinations based on CD137 (4-1BB) agonism

Biomarkers for cancer immunotherapy are an unmet medical need. The group of Daniela Thommen at the NKI recently reported on novel methodologies based on short-term cultures of patient-derived tumor fragments whose cytokine concentrations in the supernatants and activation markers on infiltrating T cells were associated with clinical response to PD-1 blockade. We set up a similar culture technology with tumor-derived fragments using mouse tumors transplanted into syngeneic immunocompetent mice to test an agonist anti-CD137 mAb and its combinations with anti-PD-1 and/or anti-TGF-β. Increases in IFNγ concentrations in the tissue culture supernatants were detected upon in-culture activation with the anti-CD137 and anti-PD-1 mAb combinations or concanavalin A as a positive control. No other cytokine from a wide array was informative of stimulation with these mAbs. Interestingly, increases in Ki67 and other activation markers were substantiated in lymphocytes from cell suspensions gathered at the end of 72 h cultures. In mice bearing bilateral tumors in which one was excised prior to in vivo anti-CD137 + anti-PD-1 treatment to perform the fragment culture evaluation, no association was found between IFNγ production from the fragments and the in vivo therapeutic outcome in the non-resected contralateral tumors. The experimental system permitted freezing and thawing of the fragments with similar functional outcomes. Using a series of patient-derived tumor fragments from excised solid malignancies, we showed IFNγ production in a fraction of the studied cases, that was conserved in frozen/thawed fragments. The small tumor fragment culture technique seems suitable to preclinically explore immunotherapy combinations.

Exploration of Immune-Modulatory Effects of Amivantamab in Combination with Pembrolizumab in Lung and Head and Neck Squamous Cell Carcinoma

Immune checkpoint inhibitors are effective first-line therapy for solid cancers. However, low response rate and acquired resistance over time has led to the need for additional therapeutic options. Here, we evaluated synergistic antitumor efficacy of EGFR × MET targeting bispecific antibody, amivantamab with PD-L1 immunotherapy, pembrolizumab in head and neck squamous cell carcinoma (HNSCC) and lung squamous cell carcinoma tumor-bearing humanized patient-derived xenograft (PDX) models. We demonstrated that pembrolizumab or amivantamab alone was ineffective and that combination treatment induced a significant reduction of tumor growth in both models (P < 0.0001 and P < 0.01, respectively). It appeared that combination of amivantamab and pembrolizumab significantly enhanced infiltration of granzyme B-producing CD8 T cells was in the TME of HNSCC PDX (P < 0.01) and enhanced neoantigen-associated central memory CD8 T cells in circulating immune cells. Analysis of single-cell RNA transcriptomics suggested that the tumor cells dramatically upregulated EGFR and MET in response to PD-L1 immunotherapy, potentially creating a metabolic state fit for tumor persistence in the tumor microenvironment (TME) and rendered pembrolizumab ineffective. We demonstrated that EGFRHIGHMETHIGH subcluster displayed an increased expression of genes implicated in production of lactate [SLC16A3 and lactate dehydrogenase A (LDHA)] compared to the EGFRLOWMETLOW cluster. Accumulation of lactate in the TME has been associated with immunosuppression by hindering the infiltration of tumor killing CD8 T and NK cells. This study proved that amivantamab reduced glycolytic markers in the EGFRHIGHMETHIGH subcluster including SLC16A3 and LDHA and highlighted remodeling of the TME by combination treatment, providing rationale for additional therapy of amivantamab with PD-1 immunotherapy.

SIGNIFICANCE

Amivantamab in synergy with pembrolizumab effectively eradicated EGFRHIGHMETHIGH tumor subcluster in the tumor microenvironment of head and neck squamous cell carcinoma and overcame resistance against anti-PD-1 immunotherapy.

Cancer cell plasticity defines response to immunotherapy in cutaneous squamous cell carcinoma

Immune checkpoint blockade (ICB) approaches have changed the therapeutic landscape for many tumor types. However, half of cutaneous squamous cell carcinoma (cSCC) patients remain unresponsive or develop resistance. Here, we show that, during cSCC progression in male mice, cancer cells acquire epithelial/mesenchymal plasticity and change their immune checkpoint (IC) ligand profile according to their features, dictating the IC pathways involved in immune evasion. Epithelial cancer cells, through the PD-1/PD-L1 pathway, and mesenchymal cancer cells, through the CTLA-4/CD80 and TIGIT/CD155 pathways, differentially block antitumor immune responses and determine the response to ICB therapies. Accordingly, the anti-PD-L1/TIGIT combination is the most effective strategy for blocking the growth of cSCCs that contain both epithelial and mesenchymal cancer cells. The expression of E-cadherin/Vimentin/CD80/CD155 proteins in cSCC, HNSCC and melanoma patient samples predicts response to anti-PD-1/PD-L1 therapy. Collectively, our findings indicate that the selection of ICB therapies should take into account the epithelial/mesenchymal features of cancer cells.

Fasting and fasting-mimicking conditions in the cancer immunotherapy era

Fasting and fasting-mimicking conditions modulate tumor metabolism and remodel the tumor microenvironment (TME), which could be exploited for the treatment of tumors. A body of evidence demonstrates that fasting and fasting-mimicking conditions can kill cancer cells, or sensitize them to the antitumor activity of standard-of-care drugs while protecting normal cells against their toxic side effects. Pre- and clinical data also suggest that immune responses are involved in these therapeutic effects. Therefore, there is increasing interest in evaluating the impact of fasting-like conditions in the efficacy of antitumor therapies based on the restoration or activation of antitumor immune responses. Here, we review the recent progress in the intersection of fasting-like conditions and current cancer treatments, with an emphasis on cancer immunotherapy.

Just how transformative will AI/ML be for immuno-oncology?

Immuno-oncology involves the study of approaches which harness the patient's immune system to fight malignancies. Immuno-oncology, as with every other biomedical and clinical research field as well as clinical operations, is in the midst of technological revolutions, which vastly increase the amount of available data. Recent advances in artificial intelligence and machine learning (AI/ML) have received much attention in terms of their potential to harness available data to improve insights and outcomes in many areas including immuno-oncology. In this review, we discuss important aspects to consider when evaluating the potential impact of AI/ML applications in the clinic. We highlight four clinical/biomedical challenges relevant to immuno-oncology and how they may be able to be addressed by the latest advancements in AI/ML. These challenges include (1) efficiency in clinical workflows, (2) curation of high-quality image data, (3) finding, extracting and synthesizing text knowledge as well as addressing, and (4) small cohort size in immunotherapeutic evaluation cohorts. Finally, we outline how advancements in reinforcement and federated learning, as well as the development of best practices for ethical and unbiased data generation, are likely to drive future innovations.

EMID2 is a novel biotherapeutic for aggressive cancers identified by in vivo screening

BACKGROUND

New drugs to tackle the next pathway or mutation fueling cancer are constantly proposed, but 97% of them are doomed to fail in clinical trials, largely because they are identified by cellular or in silico screens that cannot predict their in vivo effect.

METHODS

We screened an Adeno-Associated Vector secretome library (> 1000 clones) directly in vivo in a mouse model of cancer and validated the therapeutic effect of the first hit, EMID2, in both orthotopic and genetic models of lung and pancreatic cancer.

RESULTS

EMID2 overexpression inhibited both tumor growth and metastatic dissemination, consistent with prolonged survival of patients with high levels of EMID2 expression in the most aggressive human cancers. Mechanistically, EMID2 inhibited TGFβ maturation and activation of cancer-associated fibroblasts, resulting in more elastic ECM and reduced levels of YAP in the nuclei of cancer cells.

CONCLUSION

This is the first in vivo screening, precisely designed to identify proteins able to interfere with cancer cell invasiveness. EMID2 was selected as the most potent protein, in line with the emerging relevance of the tumor extracellular matrix in controlling cancer cell invasiveness and dissemination, which kills most of cancer patients.

Inhibiting Endothelial Cell-Mediated T Lymphocyte Apoptosis with Integrin-Targeting Peptide-Drug Conjugate Filaments for Chemoimmunotherapy of Triple-Negative Breast Cancer

Tumor-associated endothelial cells (TECs) limit antitumor immunity via inducing apoptosis of infiltrating T lymphocytes through a Fas ligand (FasL) mediated mechanism. Herein, this work creates a peptide-drug conjugate (PDC) by linking 7-ethyl-10-hydroxycamptothecin (SN38) to hydrophilic segments with either RGDR or HKD motif at their C-terminus through a glutathione-responsive linker. The PDCs spontaneously assemble into filaments in aqueous solution. The PDC filaments containing 1% of SN38-RGDR (SN38-HKD/RGDR) effectively target triple-negative breast cancer (TNBC) cells and TECs with upregulated expression of integrin, and induce immunogenic cell death (ICD) of tumor cells and FasL downregulation of TECs. SN38-HKD/RGDR increases infiltration, activity, and viability of CD8+ T cells, and thus inhibits the growth of primary tumors and pulmonary metastasis. This study highlights the synergistic modulation of cancerous cells and TECs with integrin-targeting PDC filaments as a promising strategy for TNBC chemoimmunotherapy.

Comprehensive single-cell analysis demonstrates radiotherapy-induced infiltration of macrophages expressing immunosuppressive genes into tumor in esophageal squamous cell carcinoma

Radiotherapy (RT) combined with immunotherapy is promising; however, the immune response signature in the clinical setting after RT remains unclear. Here, by integrative spatial and single-cell analyses using multiplex immunostaining (CODEX), spatial transcriptome (VISIUM), and single-cell RNA sequencing, we substantiated the infiltration of immune cells into tumors with dynamic changes in immunostimulatory and immunosuppressive gene expression after RT. In addition, our comprehensive analysis uncovered time- and cell type-dependent alterations in the gene expression profile after RT. Furthermore, myeloid cells showed prominent up-regulation of immune response-associated genes after RT. Notably, a subset of infiltrating tumor-associated myeloid cells showing PD-L1 positivity exhibited significant up-regulation of immunostimulatory (HMGB1 and ISG15), immunosuppressive (SIRPA and IDO1), and protumor genes (CXCL8, CCL3, IL-6, and IL-1AB), which can be targets of immunotherapy in combination with PD-L1. These datasets will provide information on the RT-induced gene signature to seek an appropriate target for personalized immunotherapy combined with RT and guide the timing of combination therapy.

Tumor-agnostic drug development in dMMR/MSI-H solid tumors

Mismatch repair deficiency (dMMR) or microsatellite instability-high (MSI-H) represents a distinct phenotype among solid tumors characterized by frequent frameshift mutations resulting in the generation of neoantigens that are highly immunogenic. Seminal studies identified that dMMR/MSI-H tumors are exquisitely sensitive to immune checkpoint inhibitors, which has dramatically improved outcomes for patients harboring dMMR/MSI-H tumors. Nevertheless, many patients develop resistance to single-agent immune checkpoint blockade, prompting the need for improved therapeutic options for this patient population. In this review, we highlight key studies examining the efficacy of PD1 inhibitors in the metastatic and neoadjuvant setting for patients with dMMR/MSI-H tumors, describe resistance mechanisms to immune checkpoint blockade, and discuss novel treatment approaches that are currently under investigation for dMMR/MSI-H tumors.

Intratumoral injection of IL-12-encoding mRNA targeted to CSFR1 and PD-L1 exerts potent anti-tumor effects without substantial systemic exposure

IL-12 is a potent cytokine for cancer immunotherapy. However, its systemic delivery as a recombinant protein has shown unacceptable toxicity in the clinic. Currently, the intratumoral injection of IL-12-encoding mRNA or DNA to avoid such side effects is being evaluated in clinical trials. In this study, we aimed to improve this strategy by further favoring IL-12 tethering to the tumor. We generated in vitro transcribed mRNAs encoding murine single-chain IL-12 fused to diabodies binding to CSF1R and/or PD-L1. These targeted molecules are expressed in the tumor microenvironment, especially on myeloid cells. The binding capacity of chimeric constructs and the bioactivity of IL-12 were demonstrated in vitro and in vivo. Doses as low as 0.5 μg IL-12-encoding mRNA achieved potent antitumor effects in subcutaneously injected B16-OVA and MC38 tumors. Treatment delivery was associated with increases in IL-12p70 and IFN-γ levels in circulation. Fusion of IL-12 to the diabodies exerted comparable efficacy against bilateral tumor models. However, it achieved tethering to myeloid cells infiltrating the tumor, resulting in nearly undetectable systemic levels of IL-12 and IFN-γ. Overall, tethering IL-12 to intratumoral myeloid cells in the mRNA-transferred tumors achieves similar efficacy while reducing the dangerous systemic bioavailability of IL-12.

Nano-vaccines combining customized in situ anti-PD-L1 depot for enhanced tumor immunotherapy

Low response rate of immune checkpoint blockade (ICB) has limited its clinical application. A promising strategy to overcome this limitation is the use of therapeutic cancer vaccines, which aim to induce robust immune responses that synergize with ICB through immune enhancement and immune normalization strategies. Herein, we developed a combination immunotherapy by combining nano-vaccines consisting of whole tumor cell lysates/CpG liposomes (LCLs) with an anti-PD-L1 loaded lipid gel (aPD-L1@LG). The LCLs were fabricated using cationic liposomes, while the lipid gels (LGs) were prepared by using soybean phosphatidylcholine (SPC) and glycerol dioleate (GDO). Subcutaneous administration of LCLs successfully activated dendritic cells (DCs), and intratumoral administration of anti-PD-L1@LG ensured sustained ICB activity. These results demonstrated that this combination immunotherapy enhanced anti-tumor efficacy and prolonged the survival time in melanoma by activating systemic anti-tumor immune responses. These findings highlight the potential of this rational design as a promising strategy for tumor treatment.

Considerations for the clinical development of immuno-oncology agents in cancer

Targeting of the immune system has shown to be a successful therapeutic approach in cancer, with the development of check point inhibitors (ICI) or T-cell engagers (TCE). As immuno-oncology agents modulate the immune system to attack cancer cells and do not act directly on oncogenic vulnerabilities, specific characteristics of these compounds should be taken in consideration during clinical development. In this review we will discuss relevant concepts including limitations of preclinical models, special pharmacologic boundaries, clinical development strategies such as the selection of clinical indication, line of treatment and backbone partner, as well as the endpoints and expected magnitude of benefit required at different stages of the drug development. In addition, future directions for early and late trial designs will be reviewed. Examples from approved drugs or those currently in clinical development will be discussed and options to overcome these limitations will be provided.

Recent advances in recurrent hepatocellular carcinoma therapy

Hepatocellular carcinoma (HCC) is the most prevalent form of primary liver cancer, accounting for 75%-85% of cases. Although treatments are given to cure early-stage HCC, up to 50%-70% of individuals may experience a relapse of the illness in the liver after 5 years. Research on the fundamental treatment modalities for recurrent HCC is moving significantly further. The precise selection of individuals for therapy strategies with established survival advantages is crucial to ensuring better outcomes. These strategies aim to minimize substantial morbidity, support good life quality, and enhance survival for patients with recurrent HCC. For individuals with recurring HCC after curative treatment, no approved therapeutic regimen is currently available. A recent study presented novel approaches, like immunotherapy and antiviral medication, to improve the prognosis of patients with recurring HCC with the apparent lack of data to guide the clinical treatment. The data supporting several neoadjuvant and adjuvant therapies for patients with recurring HCC are outlined in this review. We also discuss the potential for future clinical and translational investigations.

Synergistic effects of combined immunotherapy strategies in a model of multifocal hepatocellular carcinoma

Immune checkpoint-inhibitor combinations are the best therapeutic option for advanced hepatocellular carcinoma (HCC) patients, but improvements in efficacy are needed to improve response rates. We develop a multifocal HCC model to test immunotherapies by introducing c-myc using hydrodynamic gene transfer along with CRISPR-Cas9-mediated disruption of p53 in mouse hepatocytes. Additionally, induced co-expression of luciferase, EGFP, and the melanosomal antigen gp100 facilitates studies on the underlying immunological mechanisms. We show that treatment of the mice with a combination of anti-CTLA-4 + anti-PD1 mAbs results in partial clearance of the tumor with an improvement in survival. However, the addition of either recombinant IL-2 or an anti-CD137 mAb markedly improves both outcomes in these mice. Combining tumor-specific adoptive T cell therapy to the aCTLA-4/aPD1/rIL2 or aCTLA-4/aPD1/aCD137 regimens enhances efficacy in a synergistic manner. As shown by multiplex tissue immunofluorescence and intravital microscopy, combined immunotherapy treatments enhance T cell infiltration and the intratumoral performance of T lymphocytes.

Immune checkpoint therapy-current perspectives and future directions

Immune checkpoint therapy (ICT) has dramatically altered clinical outcomes for cancer patients and conferred durable clinical benefits, including cure in a subset of patients. Varying response rates across tumor types and the need for predictive biomarkers to optimize patient selection to maximize efficacy and minimize toxicities prompted efforts to unravel immune and non-immune factors regulating the responses to ICT. This review highlights the biology of anti-tumor immunity underlying response and resistance to ICT, discusses efforts to address the current challenges with ICT, and outlines strategies to guide the development of subsequent clinical trials and combinatorial efforts with ICT.

Intratumoral BO-112 in combination with radiotherapy synergizes to achieve CD8 T-cell-mediated local tumor control

BACKGROUND

Radioimmunotherapy combines irradiation of tumor lesions with immunotherapy to achieve local and abscopal control of cancer. Most immunotherapy agents are given systemically, but strategies for delivering immunotherapy locally are under clinical scrutiny to maximize efficacy and avoid toxicity. Local immunotherapy, by injecting various pathogen-associated molecular patterns, has shown efficacy both preclinically and clinically. BO-112 is a viral mimetic based on nanoplexed double-stranded RNA (poly I:C) which exerts immune-mediated antitumor effects in mice and humans on intratumoral delivery. BO-112 and focal irradiation were used to make the proof-of-concept for local immunotherapy plus radiation therapy combinations.

METHODS

Murine transplantable tumor cell lines (TS/A, MC38 and B16-OVA) were used to show increased immunogenic features under irradiation, as well as in bilateral tumor models in which only one of the lesions was irradiated or/and injected with BO-112. Flow cytometry and multiplex tissue immunofluorescence were used to determine the effects on antitumor immunity. Depletions of immune cell populations and knockout mice for the IFNAR and BATF-3 genes were used to delineate the immune system requirements for efficacy.

RESULTS

In cultures of TS/A breast cancer cells, the combination of irradiation and BO-112 showed more prominent features of immunogenic tumor cell death in terms of calreticulin exposure. Injection of BO-112 into the tumor lesion receiving radiation achieved excellent control of the treated tumor and modest delays in contralateral tumor progression. Local effects were associated with more prominent infiltrates of antitumor cytotoxic tumor lymphocytes (CTLs). Importantly, local irradiation plus BO-112 in one of the tumor lesions that enhanced the therapeutic effects of radiotherapy on distant irradiated lesions that were not injected with BO-112. Hence, this beneficial effect of local irradiation plus BO-112 on a tumor lesion enhanced the therapeutic response to radiotherapy on distant non-injected lesions.

CONCLUSION

This study demonstrates that local BO-112 immunotherapy and focal irradiation may act in synergy to achieve local tumor control. Irradiation plus BO-112 in one of the tumor lesions enhanced the therapeutic effects on distant irradiated lesions that were not injected with BO-112, suggesting strategies to treat oligometastatic patients with lesions susceptible to radiotherapy and with at least one tumor accessible for repeated BO-112 intratumoral injections.

The Lymphatic Endothelium in the Context of Radioimmuno-Oncology

The study of lymphatic tumor vasculature has been gaining interest in the context of cancer immunotherapy. These vessels constitute conduits for immune cells' transit toward the lymph nodes, and they endow tumors with routes to metastasize to the lymph nodes and, from them, toward distant sites. In addition, this vasculature participates in the modulation of the immune response directly through the interaction with tumor-infiltrating leukocytes and indirectly through the secretion of cytokines and chemokines that attract leukocytes and tumor cells. Radiotherapy constitutes the therapeutic option for more than 50% of solid tumors. Besides impacting transformed cells, RT affects stromal cells such as endothelial and immune cells. Mature lymphatic endothelial cells are resistant to RT, but we do not know to what extent RT may affect tumor-aberrant lymphatics. RT compromises lymphatic integrity and functionality, and it is a risk factor to the onset of lymphedema, a condition characterized by deficient lymphatic drainage and compromised tissue homeostasis. This review aims to provide evidence of RT's effects on tumor vessels, particularly on lymphatic endothelial cell physiology and immune properties. We will also explore the therapeutic options available so far to modulate signaling through lymphatic endothelial cell receptors and their repercussions on tumor immune cells in the context of cancer. There is a need for careful consideration of the RT dosage to come to terms with the participation of the lymphatic vasculature in anti-tumor response. Here, we provide new approaches to enhance the contribution of the lymphatic endothelium to radioimmuno-oncology.

Breast cancer cells survive chemotherapy by activating targetable immune-modulatory programs characterized by PD-L1 or CD80

Breast cancer cells must avoid intrinsic and extrinsic cell death to relapse following chemotherapy. Entering senescence enables survival from mitotic catastrophe, apoptosis and nutrient deprivation, but mechanisms of immune evasion are poorly understood. Here we show that breast tumors surviving chemotherapy activate complex programs of immune modulation. Characterization of residual disease revealed distinct tumor cell populations. The first population was characterized by interferon response genes, typified by Cd274, whose expression required chemotherapy to enhance chromatin accessibility, enabling recruitment of IRF1 transcription factor. A second population was characterized by p53 signaling, typified by CD80 expression. Treating mammary tumors with chemotherapy followed by targeting the PD-L1 and/or CD80 axes resulted in marked accumulation of T cells and improved response; however, even combination strategies failed to fully eradicate tumors in the majority of cases. Our findings reveal the challenge of eliminating residual disease populated by senescent cells expressing redundant immune inhibitory pathways and highlight the need for rational immune targeting strategies.