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Cáncer; Inmunología tumoral Càncer; Immunologia tumoral Cancer; Tumour immunology Early detection of immunotherapy-induced tumor response is of major benefit for patients but can be complicated by therapy-induced pseudoprogression. A consensus guideline-iRECIST- was developed as a modification of Response Evaluation Criteria in Solid Tumours (RECIST version 1.1). Here we describe which next steps are required to test its validity and how novel approaches for response criteria might be developed and included.

BackgroundThe survival rates for pediatric patients with relapsed and refractory tumors are poor. Successful treatment strategies are currently lacking and there remains an unmet need for novel therapies for these patients. We report here the results of a phase 1 study of talimogene laherparepvec (T-VEC) and explore the safety of this oncolytic immunotherapy for the treatment of pediatric patients with advanced non–central nervous system tumors.MethodsT-VEC was delivered by intralesional injection at 106 plaque-forming units (PFU)/ml on the first day, followed by 108 PFU/ml on the first day of week 4 and every 2 weeks thereafter. The primary objective was to evaluate the safety and tolerability as assessed by the incidence of dose-limiting toxicities (DLTs). Secondary objectives included efficacy indicated by response and survival per modified immune-related response criteria simulating the Response Evaluation Criteria in Solid Tumors (irRC-RECIST).ResultsFifteen patients were enrolled into two cohorts based on age: cohort A1 (n = 13) 12 to ≤21 years old (soft-tissue sarcoma, n = 7; bone sarcoma, n = 3; neuroblastoma, n = 1; nasopharyngeal carcinoma, n = 1; and melanoma, n = 1) and cohort B1 (n = 2) 2 to n = 2). Overall, patients received treatment for a median (range) of 5.1 (0.1, 39.4) weeks. No DLTs were observed during the evaluation period. All patients experienced at least one treatment-emergent adverse event (TEAE), and 53.3% of patients reported grade ≥3 TEAEs. Overall, 86.7% of patients reported treatment-related TEAEs. No complete or partial responses were observed, and three patients (20%) overall exhibited stable disease as the best response.ConclusionsT-VEC was tolerable as assessed by the observation of no DLTs. The safety data were consistent with the patients' underlying cancer and the known safety profile of T-VEC from studies in the adult population. No objective responses were observed.Trial RegistrationClinicalTrials.gov: NCT02756845. https://clinicaltrials.gov/ct2/show/NCT02756845.

Cancer; Immunotherapy; Toxicity Cáncer; Inmunoterapia; Toxicidad Càncer; Immunoteràpia; Toxicitat

Autoimmune diseases; Checkpoint inhibition therapy; Human immunodeficiency virus Enfermedades autoinmunes; Terapia de inhibición de puntos de control; Virus de inmunodeficiencia humana Malalties autoimmunes; Teràpia d'inhibició del punt de control; Virus de la immunodeficiència humana We reviewed the available information on the use of immune checkpoint inhibitors (ICIs) in populations with special conditions, namely, patients with HIV, tuberculosis, or underlying autoimmune disease. Available data show that treatment with ICIs is safe in patients with HIV; it is advisable, however, that these patients receive adequate antiretroviral therapy and have an undetectable viral load before ICIs are initiated. Tuberculosis reactivation has been reported with the use of ICIs, possibly due to immune dysregulation. Tuberculosis has also been associated with the use of immunosuppressors to treat immune-related adverse events (irAEs). Active tuberculosis must be ruled out in patients with symptoms or signs, and selected patients may benefit from screening for latent tuberculosis infection, although more data are required. Limited data exist regarding the safety of ICIs in patients with cancer and autoimmune disease. Data from observational studies suggest that up to 29% of patients with a preexisting autoimmune disease treated with an ICI present with an autoimmune disease flare, and 30% present with a de novo irAE of any type. The frequency of flares appears to differ according to the type of ICI received, with higher rates associated with PD-1/PD-L1 inhibitors. The most common autoimmune diseases for which patients reported flares with ICI therapy are rheumatoid arthritis, other inflammatory arthritis, and psoriasis. Most studies have reported flares or de novo irAEs associated with ICIs that were mild to moderate, with low rates of discontinuation and no deaths due to flares. Therefore, the use of ICIs in these patients is possible, but careful monitoring is required. ML-O's work is supported by the National Cancer Institute (#CA237619).

Corticosteroids; Efficacy; Immune checkpoint inhibitors Corticosteroides; Eficacia; Inhibidores del punto de control inmunitario Corticoides; Eficàcia; Inhibidors del punt de control immunitari In recent years, immunotherapy-based regimens have been included into the treatment's algorithm of several cancer types. Programmed death-1 (PD-1) and cytotoxic T lymphocyte antigen-4 (CTLA-4) interact with their ligands found on the surface of antigen presenting cells (APC) or tumor cells (PD-L1/2 and CD80/86). Through these interactions, stimulatory or inhibitory signals are established. Immune checkpoint inhibitors (ICIs), block these interactions, and when administered not only as monotherapy but also as part of combination regimens, have shown to improve survival results in multiple advanced cancers leading to an increasing number of patients treated with ICI and, as a consequence, a rise in the number of patients developing immune-related adverse events (irAEs). Presence of irAEs has been associated with greater benefit from treatment, especially when blocking PD-L1. Recent data suggests that treatment benefit persists after discontinuation of ICIs due to a treatment related adverse event, regardless of the grade. Patients experiencing grade 3-4 irAEs are at risk of toxicity recurrence after reintroducing immunotherapy and therefore, the decision to resume the treatment is challenging. In these cases, a multidisciplinary approach is always needed and several factors should be considered. Management of severe toxicities may require systemic corticosteroids which can impact on T-cell function. Due to their immunosuppressive properties, it is necessary to deeper determine how corticosteroids influence responses. In terms of overall survival (OS), the use of steroids as therapy for irAEs seems not to reduce OS and several studies have reported durable responses in patients experiencing autoimmune toxicities treated with corticosteroids.

Cancer; Antigen; Resistance Cáncer; Antígeno; Resistencia Càncer; Antigen; Resistència Despite the revolution of immunotherapy in cancer treatment, patients eventually progress due to the emergence of resistance. In this scenario, the selection of the tumor antigen can be decisive in the success of the clinical response. T cell bispecific antibodies (TCBs) are engineered molecules that include binding sites to the T cell receptor and to a tumor antigen. Using gastric CEA+/HER2+ MKN45 cells and TCBs directed against CEA or HER2, we show that the mechanism of resistance to a TCB is dependent on the tumor antigen. Acquired resistant models to a high-affinity-CEA-targeted TCB exhibit a reduction of CEA levels due to transcriptional silencing, which is reversible upon 5-AZA treatment. In contrast, a HER2-TCB resistant model maintains HER2 levels and exhibit a disruption of the interferon-gamma signaling. These results will help in the design of combinatorial strategies to increase the efficacy of cancer immunotherapies and to anticipate and overcome resistances. This work was supported by Asociación Española Contra el Cancer (AECC), Breast Cancer Research Foundation (BCRF-21-008), and Instituto de Salud Carlos III (PI19/01181). A.M.S. was funded by the Spanish Government (PFIS FI20/00188). B.M. was funded by a fellowship from PERIS (Departament de Salut, Generalitat de Catalunya). M.R.A. was funded by Agency for Management of University and Research Grants (AGAUR, 2022 FI_B2 00080). P.O.R. was funded by the BBVA. E.J.A. was funded by the AECC (POSTD211413AREN). VHIO acknowledges the Cellex Foundation for providing research facilities and equipment, the Centro de Investigación Biomédica en Red de Cáncer (CIBERONC) from the Institute of Health Carlos III (ISCIII), and the Department of Health (Generalitat de Catalunya, SLT008/18/00198 SLT008/18/00205) for their support on this research. The authors acknowledge financial support from the State Agency for Research (Agencia Estatal de Investigación) (CEX2020-001024-S/AEI/10.13039/501100011033) and for the Cancer Immunology and Immunotherapy (CAIMI-2) program funded by BBVA Foundation. We would like to remark the funding from B.M PERIS (Spain). The authors thank Dr. Anne Freimoser-Grundschober and Roche for helping provide the TCBs. The graphical abstract was created with BioRender.com.

Altres ajuts: Asociación Española Contra el Cancer (GCAEC19017ARRI); Breast Cancer Research Foundation (BCRF-21-008); AECC (POSTD211413AREN); Cancer Immunology and Immunotherapy (CAIMI-2) program funded by BBVA Foundation; Spanish Government (PFIS FI20/00188) Immunotherapy has revolutionized cancer treatment, but preclinical models are required to understand immunotherapy resistance mechanisms underlying patient relapse. This protocol describes how to generate an acquired resistance humanized in vivo model to immunotherapies in patient-derived xenografts (PDX). We detail steps to inject human CD34 + cells into NSG mice, followed by generation of immunoresistant PDX in humanized mice. This approach recapitulates the human immune system, allowing investigators to generate preclinical resistance models to different immunotherapies for identifying the resistant phenotype. For complete details on the use and execution of this protocol, please refer to and . Publisher's note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics. Immunotherapy has revolutionized cancer treatment, but preclinical models are required to understand immunotherapy resistance mechanisms underlying patient relapse. This protocol describes how to generate an acquired resistance humanized in vivo model to immunotherapies in patient-derived xenografts (PDX). We detail steps to inject human CD34 + cells into NSG mice, followed by generation of immunoresistant PDX in humanized mice. This approach recapitulates the human immune system, allowing investigators to generate preclinical resistance models to different immunotherapies for identifying the resistant phenotype.

Acute kidney injury; Immune checkpoint inhibitors; Immune-related hepatitis Lesión renal aguda; Inhibidores del punto de control inmunitario; Hepatitis relacionada con el sistema inmunitario Lesió renal aguda; Inhibidors del punt de control immunitari; Hepatitis associada a la immunitat There are differences in recommendations for the management of immune-related adverse events (irAEs) associated with immune checkpoint inhibitors (ICIs). To assess the real-world management of irAEs, three surveys regarding ICI-induced hepatitis (IIH), renal irAEs, and myositis were developed and sent to experts in each area. Fifty-six surveys were completed (17 IIH, 20 renal irAEs, and 19 myositis). All experts agreed on performing imaging in every suspected case of severe IIH. Sixty-five percent agreed on performing a liver biopsy in patients not responding to corticosteroids. The most common indication for corticosteroid use (59%) was for severe IIH not improving after discontinuation of ICIs. Additionally, 60% of the experts agreed on performing a biopsy for stage 2/3 acute kidney injury (AKI), and 70% recommended imaging for any stage of AKI. Thirty-five percent favored corticosteroids in AKI patients with creatinine levels 2–3-fold above baseline. For myositis, 58% would recommend a muscle biopsy in a patient with weakness and creatine kinase levels of 5000 U/L; 47% would also opt for an endomyocardial biopsy when the troponin levels are increased. Fifty-eight percent recommended oral corticosteroids for myositis, and 37% recommended additional therapy, mainly immunoglobulins. These results show substantial differences in expert practice patterns for the management of severe liver, kidney, and muscular irAEs. This research was funded by ISCIIII-FEDER and ISCIII-RETICS REDinREN (grant numbers PI17/00257, PI21/01292, RD16/0009/0030, and RICORS RD21/0005/0016) and Enfermedad Glomerular Compleja del Sistema Nacional de Salud (CSUR) enfermedades glomerulares complejas. Supported in part by the University of Texas MD Anderson’s Cancer Center Support Grant from the National Cancer Institute (NCI P30 CA016672).

The PANGEA-Breast trial evaluated a new chemo-immunotherapeutic combination that would synergistically induce long-term clinical benefit in HER2-negative advanced breast cancer patients. Treatment consisted of 21-day cycles of 200 mg of pembrolizumab (day 1) plus gemcitabine (days 1 and 8). The primary objective was the objective response rate (ORR). The tumor infiltrating lymphocytes (TILs) density and PD-L1 expression in tumor, and the myeloid-derived suppressor cells (MDSCs) level in peripheral blood, were analyzed to explore associations with treatment efficacy. Considering a two-stage Simon’s design, the study recruitment was stopped after its first stage as statistical assumptions were not met. A subset of 21 triple-negative breast cancer (TNBC) patients was enrolled. Their median age was 49 years, 15 patients had visceral involvement, and 16 had ≤3 metastatic locations. Treatment discontinuation due to progressive disease (PD) was reported in 16 patients. ORR was 15% (95% CI 3.2–37.9). Four patients were on treatment &gt, 6 months before PD. Grade ≥3 treatment-related adverse events were observed in 8 patients, where neutropenia was the most common. No association was found between TILs density, PD-L1 expression or MDSCs levels and treatment efficacy. ORR in TNBC patients also did not meet the assumptions, but 20% were on treatment &gt, 6 months.

Mesothelioma is a rare and aggressive tumour with dismal prognosis arising in the pleura and associated with asbestos exposure. Its incidence is on the rise worldwide. In selected patients with early-stage MPM, a maximal surgical cytoreduction in combination with additional antitumour treatment may be considered in selected patients assessed by a multidisciplinary tumor board. In patients with unresectable or advanced MPM, chemotherapy with platinum plus pemetrexed is the standard of care. Currently, no standard salvage therapy has been approved yet, but second-line chemotherapy with vinorelbine or gemcitabine is commonly used. Novel therapeutic approaches based on dual immunotherapy or chemotherapy plus immunotherapy demonstrated promising survival benefit and will probably be incorporated in the future., E. Nadal thanks the support of Health Institute Carlos III-FEDER (ISCIII) [PI14/01109 and PI18/00920].

Immunoteràpia Inmunoterapia Immunotherapy Cancer immunotherapy based on the use of antibodies targeting the so-called checkpoint inhibitors, such as programmed cell death-1 receptor, its ligand, or CTLA-4, has shown durable clinical benefit and survival improvement in melanoma and other tumors. However, there are some special situations that could be a challenge for clinical management. Persons with chronic infections, such as HIV-1 or viral hepatitis, latent tuberculosis, or a history of solid organ transplantation, could be candidates for cancer immunotherapy, but their management requires a multidisciplinary approach. The Spanish Melanoma Group (GEM) panel in collaboration with experts in virology and immunology from different centers in Spain reviewed the literature and developed evidence-based guidelines for cancer immunotherapy management in patients with chronic infections and immunosuppression. These are the first clinical guidelines for cancer immunotherapy treatment in special challenging populations. Cancer immunotherapy in chronically infected or immunosuppressed patients is feasible but needs a multidisciplinary approach in order to decrease the risk of complications related to the coexistent comorbidities. This work was supported by the Spanish Melanoma Group (GEM).

Brain metastases are the most common tumor of the brain with a dismal prognosis. A fraction of patients with brain metastasis benefit from treatment with immune checkpoint inhibitors (ICI) and the degree and phenotype of the immune cell infiltration has been used to predict response to ICI. However, the anatomical location of brain lesions limits access to tumor material to characterize the immune phenotype. Here, we characterize immune cells present in brain lesions and matched cerebrospinal fluid (CSF) using single-cell RNA sequencing combined with T cell receptor genotyping. Tumor immune infiltration and specifically CD8+ T cell infiltration can be discerned through the analysis of the CSF. Consistently, identical T cell receptor clonotypes are detected in brain lesions and CSF, confirming cell exchange between these compartments. The analysis of immune cells of the CSF can provide a non-invasive alternative to predict the response to ICI, as well as identify the T cell receptor clonotypes present in brain metastasis., The use of CSF for diagnosis of metastatic brain tumors could be of clinical and patient benefit. Here the authors undertake a single-cell RNA analysis of CSF and brain to determine whether the phenotype in the CSF is reflective of the phenotype in the tumor.

Immunotherapy has raised high expectations in the treatment of virtually every cancer. Many current efforts are focused on ensuring the efficient delivery of active cytotoxic cells to tumors. It is assumed that, once these active cytotoxic cells are correctly engaged to cancer cells, they will unfailingly eliminate the latter, provided that inhibitory factors are in check. T cell bispecific antibodies (TCBs) and chimeric antigen receptors (CARs) offer an opportunity to test this assumption. Using TCB and CARs directed against HER2, here we show that disruption of interferon-gamma signaling confers resistance to killing by active T lymphocytes. The kinase JAK2, which transduces the signal initiated by interferon-gamma, is a component repeatedly disrupted in several independently generated resistant models. Our results unveil a seemingly widespread strategy used by cancer cells to resist clearance by redirected lymphocytes. In addition, they open the possibility that long-term inhibition of interferon-gamma signaling may impair the elimination phase of immunoediting and, thus, promote tumor progression., Several mechanisms of resistance to T cell-engaging therapies have been described for solid tumors. Here, by using T cell bispecific antibodies and chimeric antigen receptors (CAR) T cells targeting HER2, the authors show that cancer cell intrinsic disruption of interferon-gamma signalling, including downregulation of JAK2, confers resistance to T-cell mediated cytotoxicity.

Treball de fi de grau en Bioinformàtica. Curs 2020-2021 Tutors: Leticia De Mattos-Arruda, Juan Blanco Heredia i Mireia Olivella Els avenços en tecnologies de seqüenciació de nova generació han accelerat la detecció de mutacions somàtiques a les cèl·lules cancerígenes. Falta una eina de bioinformàtica per predir els neoantígens. L’objectiu d’aquesta investigació és crear una eina computacional integrativa que tingui com a objectiu identificar i predir els neoantígens específics del tumor a les cèl·lules cancerígenes, combinant informació de la identificació de mutacions, l’expressió gènica, caracterització del HLA i la predicció de neoantígens. Aquesta, acaba proporcionant una llista final de neoantígens a partir dels fitxers obtinguts en la seqüenciació del genoma. L’optimització i l’estandardització dels processos de predicció de neoantígens tenen implicacions directes sobre l’eficiència del desenvolupament d’immunoteràpies contra el càncer i la salut dels pacients. Los avances en tecnologías de secuenciación de nueva generación han acelerado la detección de mutaciones somáticas en las células cancerígenas. El objetivo de esta investigación es crear una herramienta computacional integrativa que tenga como objetivo identificar y predecir los neoantígenos específicos del tumor a las células cancerígenas, combinando información de la identificación de mutaciones, la expresión génica, caracterización del HLA y la predicción de neoantígenos. Esta, acaba proporcionando una lista final de neoantígenos a partir de los ficheros obtenidos en la secuenciación del genoma. La optimización y la estandarización de los procesos de predicción de neoantígenos tienen implicaciones directas sobre la eficiencia del desarrollo de inmunoterapias contra el cáncer y la salud de los pacientes. The advances in next-generation sequencing technologies have accelerated the detection of somatic mutations in cancer cells. A universal bioinformatics pipeline for predicting neoantigens is lacking. The aim of this research is to create an integrative computational tool to identify and predict tumour-specific neoantigens in cancer cells, combining information from mutation calling, gene expression, HLA typing and neoantigen prediction. This computational tool ends up providing a final list of neoantigens starting from the raw genome sequencing files. Optimisation and standardisation of neoantigen prediction pipelines have direct implications on the efficiency of the development of cancer immunotherapies, and patients’ health.

Oncologia de precisió; Assaigs clínics; Preselecció molecular Oncología de precisión; Ensayos clínicos; Preselección molecular Precision oncology; Clinical Trials; Molecular prescreening Most academic precision oncology programs have been designed to facilitate enrollment of patients in early clinical trials with matched targeted agents. Over the last decade, major changes were seen both in the targetable molecular alteration landscape and in drug development trends. In this article, we describe how the Vall d’Hebron Institute of Oncology molecular prescreening program adapted to a dynamic model of biomarker-drug codevelopment. We started with a tumor-agnostic hotspot mutation panel plus in situ hybridization and immunohistochemistry of selected markers and subsequently transitioned to tumor-specific amplicon-based next-generation sequencing (NGS) tests together with custom copy number, fusion, and outlier gene expression panels. All assays are optimized for archived formalin-fixed paraffin-embedded tumor tissues without matched germline sequencing. In parallel, biomarker-matched trials evolved from a scenario of few targets and large populations (such as PI3K inhibitors in PIK3CA mutants) to a complex situation with many targets and small populations (such as multiple targetable fusion events). Recruitment rates in clinical trials with mandatory biomarkers decreased over the last 3 years. Molecular tumor board meetings proved critical to guide oncologists on emerging biomarkers for clinical testing and interpretation of NGS results. The substantial increase of immunotherapy trials had a major impact in target prioritization and guided clinical implementation of new markers, such as tumor mutational burden, with larger exon-based NGS assays and gene expression signatures to capture microenvironment infiltration patterns. This new multiomics era of precision oncology is expected to increase the opportunities for early clinical trial matching.

[Background] Sarcomas exhibit low expression of factors related to immune response, which could explain the modest activity of PD-1 inhibitors. A potential strategy to convert a cold into an inflamed microenvironment lies on a combination therapy. As tumor angiogenesis promotes immunosuppression, we designed a phase Ib/II trial to test the double inhibition of angiogenesis (sunitinib) and PD-1/PD-L1 axis (nivolumab)., [Methods] This single-arm, phase Ib/II trial enrolled adult patients with selected subtypes of sarcoma. Phase Ib established two dose levels: level 0 with sunitinib 37.5 mg daily from day 1, plus nivolumab 3 mg/kg intravenously on day 15, and then every 2 weeks; and level −1 with sunitinib 37.5 mg on the first 14 days (induction) and then 25 mg per day plus nivolumab on the same schedule. The primary endpoint was to determine the recommended dose for phase II (phase I) and the 6-month progression-free survival rate, according to Response Evaluation Criteria in Solid Tumors 1.1 (phase II)., [Results] From May 2017 to April 2019, 68 patients were enrolled: 16 in phase Ib and 52 in phase II. The recommended dose of sunitinib for phase II was 37.5 mg as induction and then 25 mg in combination with nivolumab. After a median follow-up of 17 months (4–26), the 6-month progression-free survival rate was 48% (95% CI 41% to 55%). The most common grade 3–4 adverse events included transaminitis (17.3%) and neutropenia (11.5%)., [Conclusions] Sunitinib plus nivolumab is an active scheme with manageable toxicity in the treatment of selected patients with advanced soft tissue sarcoma, with almost half of patients free of progression at 6 months., [Trial registration number] NCT03277924., This work was supported by GEIS and ISG. BMS and Pfizer provided drug supply and partial funding for shipping. Translational studies were partially funded by Beca Buesa from the GEIS group.

Càncer en els infants; Immunoteràpia; Medicina basada en l'evidència Cancer in children; Immunotherapy; Evidence-based medicine Cáncer en los niños; Inmunoterapia; Medicina basada en la evidencia L'any 2010 es va publicar, dins de la col·lecció “Informes de Evaluación de Tecnologías Sanitarias”, un informe sobre immunoteràpia anti-GD2 en pacients amb neuroblastoma d'alt risc. L'objectiu del present informe és actualitzar-ne l'anterior amb la nova evidència disponible sobre l'eficàcia i la seguretat dels anticossos monoclonals anti-GD2 en pacients amb neuroblastoma d'alt risc. In 2010, a report on anti-GD2 immunotherapy in patients with high-risk neuroblastoma was published in the "Sanitary Technology Assessment Reports" collection. The objective of the present report is to update the previous with the new evidence available on the efficacy and safety of anti-GD2 monoclonal antibodies in patients with high risk neuroblastoma. En 2010 se publicó, dentro de la colección "Informes de Evaluación de Tecnologías Sanitarias", un informe sobre inmunoterapia anti-GD2 en pacientes con neuroblastoma de alto riesgo. El objetivo del presente informe es actualizar el anterior con la nueva evidencia disponible sobre la eficacia y la seguridad de los anticuerpos monoclonales anti-GD2 en pacientes con neuroblastoma de alto riesgo.

Immunoterapia; Pembrolizumab; neoplàsies mamàries triple-negatives Inmunoterapia; Pembrolizumab; neoplasias mamarias triple-negativas Immunotherapy; Pembrolizumab; triple-negative breast neoplasms Background: Treatment options for previously treated metastatic triple-negative breast cancer (mTNBC) are limited. In cohort A of the phase II KEYNOTE-086 study, we evaluated pembrolizumab as second or later line of treatment for patients with mTNBC. Patients and methods: Eligible patients had centrally confirmed mTNBC, ?1 systemic therapy for metastatic disease, prior treatment with anthracycline and taxane in any disease setting, and progression on or after the most recent therapy. Patients received pembrolizumab 200mg intravenously every 3 weeks for up to 2 years. Primary end points were objective response rate in the total and PD-L1–positive populations, and safety. Secondary end points included duration of response, disease control rate (percentage of patients with complete or partial response or stable disease for ?24 weeks), progression-free survival, and overall survival. Results: All enrolled patients (N¼170) were women, 61.8% had PD-L1–positive tumors, and 43.5% had received ?3 previous lines of therapy for metastatic disease. ORR (95% CI) was 5.3% (2.7–9.9) in the total and 5.7% (2.4–12.2) in the PD-L1–positive populations. Disease control rate (95% CI) was 7.6% (4.4–12.7) and 9.5% (5.1–16.8), respectively. Median duration of response was not reached in the total (range, 1.2þ–21.5þ) and in the PD-L1–positive (range, 6.3–21.5þ) populations. Median PFS was 2.0 months (95% CI, 1.9–2.0), and the 6-month rate was 14.9%. Median OS was 9.0 months (95% CI, 7.6–11.2), and the 6-month rate was 69.1%. Treatment-related adverse events occurred in 103 (60.6%) patients, including 22 (12.9%) with grade 3 or 4 AEs. There were no deaths due to AEs. Conclusions: Pembrolizumab monotherapy demonstrated durable antitumor activity in a subset of patients with previously treated mTNBC and had a manageable safety profile. This work was supported by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.