Incongruity between T cell receptor recognition of breast cancer hotspot mutations ESR1 Y537S and D538G following exogenous peptide loading versus endogenous antigen processing.

T cell receptor engineered T cell (TCR T) therapies have shown recent efficacy against certain types of solid metastatic cancers. However, to extend TCR T therapies to treat more patients across additional cancer types, new TCRs recognizing cancer-specific antigen targets are needed. Driver mutations in AKT1, ESR1, PIK3CA, and TP53 are common in patients with metastatic breast cancer (MBC) and if immunogenic could serve as ideal tumor-specific targets for TCR T therapy to treat this disease. Through IFN-γ ELISpot screening of in vitro expanded neopeptide-stimulated T cell lines from healthy donors and MBC patients, we identified reactivity towards 11 of 13 of the mutations. To identify neopeptide-specific TCRs, we then performed single-cell RNA sequencing of one of the T cell lines following neopeptide stimulation. Here, we identified an ESR1 Y537S specific T cell clone, clonotype 16, and an ESR1 Y537S/D538G dual-specific T cell clone, clonotype 21, which were HLA-B*40:02 and HLA-C*01:02 restricted, respectively. TCR Ts expressing these TCRs recognized and killed target cells pulsed with ESR1 neopeptides with minimal activity against ESR1 WT peptide. However, these TCRs failed to recognize target cells expressing endogenous mutant ESR1. To investigate the basis of this lack of recognition we performed immunopeptidomics analysis of a mutant-overexpressing lymphoblastoid cell line and found that the ESR1 Y537S neopeptide was not endogenously processed, despite binding to HLA-B*40:02 when exogenously pulsed onto the target cell. These results indicate that stimulation of T cells that likely derive from the naïve repertoire with pulsed minimal peptides may lead to the expansion of clones that recognize non-processed peptides, and highlights the importance of using methods that selectively expand T cells with specificity for antigens that are efficiently processed and presented.

Quantitative assessment of the troCarWash™ system for automated laparoscopic camera cleaning.

BACKGROUND: Soilage of the surgical endoscope occurs frequently during minimally invasive surgery. The resultant impairment of visualization of the surgical field compromises patient safety, prolongs operative times, and frustrates surgeons. The standard practice for cleaning the surgical camera involves a disruption in the conduct of surgery by completely removing the endoscope from the field, manually cleaning its lens, treating it with a surfactant, and reinserting it into the patient; after which the surgeon resumes the procedure. METHODS: We developed an automated solution for in vivo endoscope cleaning in minimally invasive surgery- a port that detects the position of the endoscope in its distal lumen, and precisely and automatically delivers a pressurized mist of cleaning solution to the lens of the camera. No additions to the scope and minimal user interaction with the port are required. We tested the efficacy of this troCarWash™ device in a porcine model of laparoscopy. Four board-certified general surgeons were instructed to soil and then clean the laparoscope using the device. Representative pre- and post-clean images were exported from the surgical video and clarity was graded (1) digitally by a canny edge detection algorithm, and (2) subjectively by 3 blinded, unbiased observers using a semi-quantitative scale. RESULTS: We observed statistically significant improvements in clarity by each method and for each surgeon, and we noted significant correlation between digital and subjective scores. CONCLUSION: Based on these data, we conclude that the troCarWash™ effectively restored impaired visualization in a large animal model of laparoscopy.

Transthoracic Robotic First and Cervical Rib Resection for Thoracic Outlet Syndrome.

INTRODUCTION: Neurogenic thoracic outlet syndrome (TOS) is a musculoskeletal condition in which the brachial plexus is dynamically compressed within the scalene triangle, an anatomic space bordered by the anterior and middle scalene muscles and the first rib. In some cases, an offending cervical rib is present. Traditional surgical approaches to first rib resection and scalenectomy are limited by exposure, require retraction of neurovascular structures, and result in morbidity. METHODS: We describe a novel transthoracic robotic approach to first/cervical rib resection that overcomes these limitations, and we review its early clinical outcomes. RESULTS: Robotic first rib resection (FRR) is crystallized into 12 distinct steps, each with detailed video commentary, and nuances specific to neurogenic and venous TOS cases are provided. Published data supports decreased surgical morbidity of robotic FRR compared with open cases. CONCLUSIONS: Robotic FRR offers advantages over traditional operative approaches including improved exposure and elimination of retraction of neurovascular structures, which result in improved safety.

A combination of intrinsic and extrinsic features improves prognostic prediction in malignant pleural mesothelioma.

BACKGROUND: Malignant pleural mesothelioma (MPM) is a lung pleural cancer with very poor disease outcome. With limited curative MPM treatment available, it is vital to study prognostic biomarkers to categorise different patient risk groups. METHODS: We defined gene signatures to separately characterise intrinsic and extrinsic features, and investigated their interactions in MPM tumour samples. Specifically, we calculated gene signature scores to capture the downstream pathways of major mutated driver genes (BAP1, NF2, SETD2 and TP53) as tumour-intrinsic features. Similarly, we inferred the infiltration levels for major immune cells in the tumour microenvironment to characterise tumour-extrinsic features. Lastly, we integrated these features with clinical factors to predict prognosis in MPM. RESULTS: The gene signature scores were more prognostic than the corresponding genomic mutations, mRNA and protein expression. High immune infiltration levels were associated with prolonged survival. The integrative model indicated that tumour features provided independent prognostic values than clinical factors and were complementary with each other in survival prediction. CONCLUSIONS: By using an integrative model that combines intrinsic and extrinsic features, we can more correctly predict the clinical outcomes of patients with MPM.

Clinical Understaging, Treatment Response, and Survival Among Esophageal Adenocarcinoma Patients.

INTRODUCTION: Selecting appropriate management for patients with esophageal adenocarcinoma (EA) is predicated on accurate clinical staging information. Inaccurate information could lead to inappropriate treatment and suboptimal survival. We investigated the relationship between staging accuracy, treatment, and survival. METHODS: This was a national cohort study of EA patients in the National Cancer Data Base (2006-2015) treated with upfront resection or neoadjuvant therapy (NAT). Clinical and pathological staging information was used to ascertain staging concordance for each patient. For NAT patients, Bayesian analysis was used to account for potential downstaging. We evaluated the association between staging concordance, receipt of NAT, and survival through hierarchical logistic regression and multivariable Cox regression. RESULTS: Among 7635 EA patients treated at 877 hospitals, 3038 had upfront resection and 4597 NAT followed by surgery. Relative to accurately staged patients, understaging was associated with a lower likelihood (odds ratio [OR] 0.04 95% confidence interval [CI] 0.02-0.05) while overstaging was associated with a greater likelihood of receiving NAT (OR 1.98 [1.53-2.56]). Relative to upfront surgery, treatment of cT1N0 patients with NAT was associated with a higher risk of death (HR 3.08 [2.36-4.02]). For accurately or overstaged cT3-T4 patients, NAT was associated with a lower risk of death whether downstaging occurred (ypN0 disease-HR 0.67 [0.49-0.92]; N+ disease-HR 0.55 [0.45-0.66]) or not (ypN + disease-HR 0.78 [95% CI 0.65-0.93]). CONCLUSIONS: Clinical understaging is associated with receipt of NAT which in turn may have a stage-specific impact on patients' survival regardless of treatment response. Guidelines should account for the possibility of inaccurate clinical staging.

Allogeneic IgG combined with dendritic cell stimuli induce antitumour T-cell immunity.

Whereas cancers grow within host tissues and evade host immunity through immune-editing and immunosuppression, tumours are rarely transmissible between individuals. Much like transplanted allogeneic organs, allogeneic tumours are reliably rejected by host T cells, even when the tumour and host share the same major histocompatibility complex alleles, the most potent determinants of transplant rejection. How such tumour-eradicating immunity is initiated remains unknown, although elucidating this process could provide the basis for inducing similar responses against naturally arising tumours. Here we find that allogeneic tumour rejection is initiated in mice by naturally occurring tumour-binding IgG antibodies, which enable dendritic cells (DCs) to internalize tumour antigens and subsequently activate tumour-reactive T cells. We exploited this mechanism to treat autologous and autochthonous tumours successfully. Either systemic administration of DCs loaded with allogeneic-IgG-coated tumour cells or intratumoral injection of allogeneic IgG in combination with DC stimuli induced potent T-cell-mediated antitumour immune responses, resulting in tumour eradication in mouse models of melanoma, pancreas, lung and breast cancer. Moreover, this strategy led to eradication of distant tumours and metastases, as well as the injected primary tumours. To assess the clinical relevance of these findings, we studied antibodies and cells from patients with lung cancer. T cells from these patients responded vigorously to autologous tumour antigens after culture with allogeneic-IgG-loaded DCs, recapitulating our findings in mice. These results reveal that tumour-binding allogeneic IgG can induce powerful antitumour immunity that can be exploited for cancer immunotherapy.

Digital Biomarkers for the Objective Assessment of Disability in Neurogenic Thoracic Outlet Syndrome.

Neurogenic thoracic outlet syndrome (nTOS) is a musculoskeletal disorder in which compression of the brachial plexus between the scalene muscles of the neck and the first rib results in disabling upper extremity pain and paresthesia. Currently there are no objective metrics for assessing the disability of nTOS or for monitoring response to its therapy. We aimed to develop digital biomarkers of upper extremity motor capacity that could objectively measure the disability of nTOS using an upper arm inertial sensor and a 20-s upper extremity task that provokes nTOS symptoms. We found that digital biomarkers of slowness, power, and rigidity statistically differentiated the affected extremities of patients with nTOS from their contralateral extremities (n = 16) and from the extremities of healthy controls (n = 13); speed and power had the highest effect sizes. Digital biomarkers representing slowness, power, and rigidity correlated with patient-reported outcomes collected with the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire and the visual analog scale of pain (VAS); speed had the highest correlation. Digital biomarkers of exhaustion correlated with failure of physical therapy in treating nTOS; and digital biomarkers of slowness, power, and exhaustion correlated with favorable response to nTOS surgery. In conclusion, sensor-derived digital biomarkers can objectively assess the impairment of motor capacity resultant from nTOS, and correlate with patient-reported symptoms and response to therapy.

Evaluation and treatment of thoracic outlet syndrome during the global pandemic due to SARS-CoV-2 and COVID-19.

The global SARS-CoV-2/COVID-19 pandemic has required a reduction in nonemergency treatment for a variety of disorders. This report summarizes conclusions of an international multidisciplinary consensus group assembled to address evaluation and treatment of patients with thoracic outlet syndrome (TOS), a group of conditions characterized by extrinsic compression of the neurovascular structures serving the upper extremity. The following recommendations were developed in relation to the three defined types of TOS (neurogenic, venous, and arterial) and three phases of pandemic response (preparatory, urgent with limited resources, and emergency with complete diversion of resources). • In-person evaluation and treatment for neurogenic TOS (interventional or surgical) are generally postponed during all pandemic phases, with telephone/telemedicine visits and at-home physical therapy exercises recommended when feasible. • Venous TOS presenting with acute upper extremity deep venous thrombosis (Paget-Schroetter syndrome) is managed primarily with anticoagulation, with percutaneous interventions for venous TOS (thrombolysis) considered in early phases (I and II) and surgical treatment delayed until pandemic conditions resolve. Catheter-based interventions may also be considered for selected patients with central subclavian vein obstruction and threatened hemodialysis access in all pandemic phases, with definitive surgical treatment postponed. • Evaluation and surgical treatment for arterial TOS should be reserved for limb-threatening situations, such as acute upper extremity ischemia or acute digital embolization, in all phases of pandemic response. In late pandemic phases, surgery should be restricted to thrombolysis or brachial artery thromboembolectomy, with more definitive treatment delayed until pandemic conditions resolve.

Integrated genomic analysis of recurrence-associated small non-coding RNAs in oesophageal cancer.

OBJECTIVE: Oesophageal squamous cell carcinoma (ESCC) is a heterogeneous disease with variable outcomes that are challenging to predict. A better understanding of the biology of ESCC recurrence is needed to improve patient care. Our goal was to identify small non-coding RNAs (sncRNAs) that could predict the likelihood of recurrence after surgical resection and to uncover potential molecular mechanisms that dictate clinical heterogeneity. DESIGN: We developed a robust prediction model for recurrence based on the analysis of the expression profile data of sncRNAs from 108 fresh frozen ESCC specimens as a discovery set and assessment of the associations between sncRNAs and recurrence-free survival (RFS). We also evaluated the mechanistic and therapeutic implications of sncRNA obtained through integrated analysis from multiple datasets. RESULTS: We developed a risk assessment score (RAS) for recurrence with three sncRNAs (microRNA (miR)-223, miR-1269a and nc886) whose expression was significantly associated with RFS in the discovery cohort (n=108). RAS was validated in an independent cohort of 512 patients. In multivariable analysis, RAS was an independent predictor of recurrence (HR, 2.27; 95% CI, 1.26 to 4.09; p=0.007). This signature implies the expression of ΔNp63 and multiple alterations of driver genes like PIK3CA. We suggested therapeutic potentials of immune checkpoint inhibitors in low-risk patients, and Polo-like kinase inhibitors, mammalian target of rapamycin (mTOR) inhibitors, and histone deacetylase inhibitors in high-risk patients. CONCLUSION: We developed an easy-to-use prognostic model with three sncRNAs as robust prognostic markers for postoperative recurrence of ESCC. We anticipate that such a stratified and systematic, tumour-specific biological approach will potentially contribute to significant improvement in ESCC treatment.

Utility of Adjuvant Chemotherapy After Neoadjuvant Chemoradiation and Esophagectomy for Esophageal Cancer.

OBJECTIVE: To determine whether adjuvant chemotherapy (AC) after neoadjuvant chemoradiation and esophagectomy is associated with improved overall survival for patients with locally advanced esophageal cancer, and to evaluate how pathologic disease response to neoadjuvant treatment impacts this effect. BACKGROUND: Neoadjuvant chemoradiation is currently the preferred management approach for locoregional esophageal cancer. Although there is interest in the use of AC, the benefit of systemic therapy after neoadjuvant chemoradiation and esophagectomy is unclear. METHODS: Retrospective cohort study of patients with esophageal cancer treated with neoadjuvant chemoradiation and esophagectomy in the National Cancer Data Base (2006-2012). RESULTS: Among 3592 patients with esophageal cancer (84.7% adenocarcinoma, 15.2% squamous cell carcinoma), 335 (9.3%) were treated with AC. AC was not associated with a significantly lower risk of death among patients with no residual disease (ypT0N0) or residual non-nodal disease (ypT+N0). Among patients with residual nodal disease (ypTanyN+), AC was associated with a 30% lower risk of death in the overall cohort [hazard ratio (HR) 0.70, (0.57-0.85)] and among those with adenocarcinoma [HR 0.69 (0.57-0.85)]. Using a 90-day postoperative landmark, findings were similar. Among patients with postoperative length of stay ≤10 days and no unplanned readmission, AC was associated with approximately 40% lower risk of death among patients with residual nodal disease [overall cohort, HR 0.63 (0.48-0.84); adenocarcinoma, HR 0.66 (0.49-0.88)]. CONCLUSIONS: AC after neoadjuvant chemoradiation and esophagectomy is associated with improved survival in patients with residual nodal disease. Our findings suggest AC may provide additional benefit for esophageal cancer patients, and merits further investigation.

Diameter of Solid Tumor Component Alone Should be Used to Establish T Stage in Lung Adenocarcinoma.

PURPOSE: The computed tomographic (CT) appearance of so-called ground glass components within lung adenocarcinomas correlate with noninvasive tumor histology, and solid radiographic components correlate with invasive histology. We hypothesized that T stage might be more accurately applied by considering the solid component nodule diameter rather than total nodule diameter. METHODS: We identified 74 patients with a solitary lung adenocarcinoma who underwent resection without receiving neoadjuvant therapy. Maximum total diameter and solid diameter of the nodules were measured on CT scans performed within 3 months of surgery. Cox proportional hazard modeling and Kaplan-Meier analyses were performed to determine whether total nodule diameter or solid component diameter was more predictive of overall survival. RESULTS: Thirty-three patients (45 %) had a solid nodule and 41 patients (55 %) had a part-solid nodule. Most patients were white (59 %) and female (69 %), and 42 % had never smoked. Seventy-four percent underwent lobectomy and 23 % sublobar resection. Sixty-six percent had pathologic stage I disease, 22 % stage II, and 12 % stage IIIA. Mean ± SD total and solid nodule diameters were 32.1 ± 17.5 and 24.8 ± 18.0 mm, respectively (p = 0.01). Among patients with part-solid nodules, multivariate modeling incorporating significant univariate predictors of survival (age, gender, procedure, N descriptor) revealed that maximum solid diameter was associated with overall survival (hazard ratio 1.4, p = 0.01), while maximum total diameter was not. CONCLUSIONS: In a largely non-Asian cohort undergoing resection for adenocarcinoma, radiographic diameter of the solid component of a part-solid lesion on CT predicts overall survival better than total lesion diameter. These data provide further evidence to support altering the T descriptor for lung adenocarcinoma for part-solid nodules.

Clonal gene signatures predict prognosis in mesothelioma and lung adenocarcinoma.

Malignant pleural mesothelioma (MPM) is a rare but lethal pleural cancer with high intratumor heterogeneity (ITH). A recent study in lung adenocarcinoma has developed a clonal gene signature (ORACLE) from multiregional transcriptomic data and demonstrated high prognostic values and reproducibility. However, such a strategy has not been tested in other types of cancer with high ITH. We aimed to identify biomarkers from multi-regional data to prognostically stratify MPM patients. We generated a multiregional RNA-seq dataset for 78 tumor samples obtained from 26 MPM patients, each with one sample collected from a superior, lateral, and inferior region of the tumor. By integrating this dataset with the Cancer Genome Atlas MPM RNA-seq data, we selected 29 prognostic genes displaying high variability across different tumors but low ITH, which named PRACME (Prognostic Risk Associated Clonal Mesothelioma Expression). We evaluated PRACME in two independent MPM datasets and demonstrated its prognostic values. Patients with high signature scores are associated with poor prognosis after adjusting established clinical factors. Interestingly, the PRACME and the ORACLE signatures defined respectively from MPM and lung adenocarcinoma cross-predict prognosis between the two cancer types. Further investigation indicated that the cross-prediction ability might be explained by the high similarity between the two cancer types in their genomic regions with copy number variation, which host many clonal genes. Overall, our clonal signature PRACME provided prognostic stratification in MPM and this study emphasized the importance of multi-regional transcriptomic data for prognostic stratification based on clonal genes.

Pathophysiology and Management of Chest Wall Pain after Surgical and Non-Surgical Local Therapies for Lung Cancer.

Chest wall pain syndromes can emerge following local therapies for lung cancer and can adversely affect patients' quality-of-life. This can occur after lung surgery, radiation therapy, or percutaneous image-guided thermal ablation. This review describes the multifactorial pathophysiology of chest wall pain syndromes that develop following surgical and non-surgical local therapies for lung cancer and summarizes evidence-based management strategies for inflammatory, neuropathic, myofascial, and osseous pain. It discusses a step-wise approach to treating chest wall pain that begins with non-opioid oral analgesics and includes additional pharmacologic treatments as clinically indicated, such as anticonvulsants, serotonin and norepinephrine reuptake inhibitors, tricyclic antidepressants, and various topical treatments. For myofascial pain, physical medicine techniques, such as acupuncture, trigger point injections, deep tissue massage, and intercostal myofascial release can also offer pain relief. For severe or refractory cases, opioid analgesics, intercostal nerve blocks, or intercostal nerve ablations may be indicated. Fortunately, palliation of treatment-related chest wall pain syndromes can be managed by most clinical providers, regardless of the type of local therapy utilized for a patient's lung cancer treatment. In cases where a patient's pain fails to respond to initial medical management, clinicians can consider referring to a pain specialist who can tailor a more specific pharmacologic approach or perform a procedural intervention to relieve pain.

Intratumoral immune triads are required for immunotherapy-mediated elimination of solid tumors.

Tumor-specific CD8+ T cells are frequently dysfunctional and unable to halt tumor growth. We investigated whether tumor-specific CD4+ T cells can be enlisted to overcome CD8+ T cell dysfunction within tumors. We find that the spatial positioning and interactions of CD8+ and CD4+ T cells, but not their numbers, dictate anti-tumor responses in the context of adoptive T cell therapy as well as immune checkpoint blockade (ICB): CD4+ T cells must engage with CD8+ T cells on the same dendritic cell during the effector phase, forming a three-cell-type cluster (triad) to license CD8+ T cell cytotoxicity and cancer cell elimination. When intratumoral triad formation is disrupted, tumors progress despite equal numbers of tumor-specific CD8+ and CD4+ T cells. In patients with pleural mesothelioma treated with ICB, triads are associated with clinical responses. Thus, CD4+ T cells and triads are required for CD8+ T cell cytotoxicity during the effector phase and tumor elimination.

Technical Aspects of Robotic First Rib Resection.

Robot-assisted thoracoscopic surgery for the treatment of thoracic outlet syndrome is a novel approach that continues to increase in popularity due to advantages compared with traditional open first rib resection. Following publication of the Society of Vascular Surgeons expert statement in 2016, the diagnosis and management of thoracic outlet syndrome is favorably evolving. Technical mastery of the operation requires precise knowledge of anatomy, comfort with robotic surgical platforms, and understanding of the disease.

Robotic First Rib Resection and Robotic Chest Wall Resection.

Robot-assisted thoracoscopic surgery for the treatment of thoracic outlet syndrome and chest wall lesions are burgeoning topics on thoracic surgery. Following publication of the Society of Vascular Surgeons expert statement in 2016, the diagnosis and management of thoracic outlet syndrome is favorably evolving. Robot-assisted first rib resection is a novel approach to the surgical management of thoracic outlet syndrome that may have advantages compared with traditional open surgical approaches. Robot-assisted chest wall resection is technically feasible for a variety of chest wall conditions and may also have advantages compared with thoracotomy approaches.

Pleurectomy and decortication are associated with better survival for bicavitary cytoreductive surgery for mesothelioma compared with extrapleural pneumonectomy.

OBJECTIVES: Mesothelioma is a nearly uniformly fatal tumor. Multimodality therapy including cytoreductive surgery and chemotherapy is associated with long-term survival in some patients. Cytoreductive surgery for thoracic disease includes a lung-sparing operation called an "extended pleurectomy/decortication" or a lung-sacrificing surgery called an "extrapleural pneumonectomy." The benefit of cytoreductive surgery for bicavitary disease (chest and abdomen) is poorly understood. Our objective was to evaluate the long-term survivals for patients undergoing cytoreductive surgery for bicavitary disease and to determine whether any prognostic factors were associated with outcome. METHODS: We reviewed our Institutional Review Board-approved, institutional, International Association for the Study of Lung Cancer Mesothelioma Staging Project database. Inclusion criteria were all patients who underwent cytoreductive surgery for bicavitary disease. Overall survival was calculated by Kaplan-Meier methodology. All International Association for the Study of Lung Cancer database elements were evaluated by univariable analysis. RESULTS: From February 2014 to August 2021, 440 patients with mesothelioma were evaluated. Fourteen patients (3%) underwent cytoreductive surgery of both chest and abdomen as a planned 2-stage operation. Most patients (13/14; 93%) underwent chest surgery before abdomen surgery. For the entire cohort, the median overall survival was 33.6 months with a 5-year survival of 20%. Extended pleurectomy/decortication was associated with a better outcome compared with extrapleural pneumonectomy, with median overall survivals of 58.2 versus 13.5 months, respectively. CONCLUSIONS: For a highly selected group of patients with bicavitary mesothelioma, long-term survival can be achieved with an aggressive, staged surgical approach. The patients who undergo extended pleurectomy/decortication with preservation of the lung appear to have more favorable outcomes compared with patients undergoing extrapleural pneumonectomy.

Intratumoral immune triads are required for adoptive T cell therapy-mediated elimination of solid tumors.

Tumor-reactive CD8 T cells found in cancer patients are frequently dysfunctional, unable to halt tumor growth. Adoptive T cell transfer (ACT), the administration of large numbers of in vitro-generated cytolytic tumor-reactive CD8 T cells, is an important cancer immune therapy being pursued. However, a limitation of ACT is that transferred CD8 T cells often rapidly lose effector function, and despite exciting results in certain malignancies, few ACT clinical trials have shown responses in solid tumors. Here, we developed preclinical cancer mouse models to investigate if and how tumor-specific CD4 T cells can be enlisted to overcome CD8 T cell dysfunction in the setting of ACT. In situ confocal microscopy of color-coded cancer cells, tumor-specific CD8 and CD4 T cells, and antigen presenting cells (APC), combined with functional studies, revealed that the spatial positioning and interactions of CD8 and CD4 T cells, but not their numbers, dictates ACT efficacy and anti-tumor responses. We uncover a new role of antigen-specific CD4 T cells in addition to the known requirement for CD4 T cells during priming/activation of naïve CD8 T cells. CD4 T cells must co-engage with CD8 T cells and APC cross-presenting CD8- and CD4-tumor antigens during the effector phase, forming a three-cell-cluster (triad), to license CD8 T cell cytotoxicity and mediate cancer cell elimination. Triad formation transcriptionally and epigenetically reprogram CD8 T cells, prevent T cell dysfunction/exhaustion, and ultimately lead to the elimination of large established tumors and confer long-term protection from recurrence. When intratumoral triad formation was disrupted, adoptively transferred CD8 T cells could not be reprogrammed, and tumors progressed despite equal numbers of tumor-infiltrating CD8 and CD4 T cells. Strikingly, the formation of CD4 T cell::CD8 T cell::APC triads in tumors of patients with lung cancers treated with immune checkpoint blockade was associated with clinical responses, but not CD4::APC dyads or overall numbers of CD8 or CD4 T cells, demonstrating the importance of triads in non-ACT settings in humans. Our work uncovers intratumoral triads as a key requirement for anti-tumor immunity and a new role for CD4 T cells in CD8 T cell cytotoxicity and cancer cell eradication.

A Phase II Window of Opportunity Study of Neoadjuvant PD-L1 versus PD-L1 plus CTLA-4 Blockade for Patients with Malignant Pleural Mesothelioma.

PURPOSE: We report the results of a phase II, randomized, window-of-opportunity trial of neoadjuvant durvalumab versus durvalumab plus tremelimumab followed by surgery in patients with resectable malignant pleural mesothelioma (MPM; NCT02592551). PATIENTS AND METHODS: The primary objective was alteration of the intratumoral CD8/regulatory T cell (Treg) ratio after combination immune checkpoint blockade (ICB) therapy. Secondary and exploratory objectives included other changes in the tumor microenvironment, survival, safety, tumor pathologic response (PR), and systemic immune responses. RESULTS: Nine patients received monotherapy and 11 received combination therapy. Seventeen of the 20 patients (85%) receiving ICB underwent planned thoracotomy. Both ICB regimens induced CD8 T-cell infiltration into MPM tumors but did not alter CD8/Treg ratios. At 34.1 months follow-up, patients receiving combination ICB had longer median overall survival (not reached) compared with those receiving monotherapy (14.0 months). Grade ≥3 immunotoxicity occurred in 8% of patients in the monotherapy group and 27% of patients in the combination group. Tumor PR occurred in 6 of 17 patients receiving ICB and thoracotomy (35.3%), among which major PR (>90% tumor regression) occurred in 2 (11.8%). Single-cell profiling of tumor, blood, and bone marrow revealed that combination ICB remodeled the immune contexture of MPM tumors; mobilized CD57+ effector memory T cells from the bone marrow to the circulation; and increased the formation of tertiary lymphoid structures in MPM tumors that were rich in CD57+ T cells. CONCLUSIONS: These data indicate that neoadjuvant durvalumab plus tremelimumab orchestrates de novo systemic immune responses that extend to the tumor microenvironment and correlate with favorable clinical outcomes.

Modulation of the proteostasis network promotes tumor resistance to oncogenic KRAS inhibitors.

Despite substantial advances in targeting mutant KRAS, tumor resistance to KRAS inhibitors (KRASi) remains a major barrier to progress. Here, we report proteostasis reprogramming as a key convergence point of multiple KRASi-resistance mechanisms. Inactivation of oncogenic KRAS down-regulated both the heat shock response and the inositol-requiring enzyme 1α (IRE1α) branch of the unfolded protein response, causing severe proteostasis disturbances. However, IRE1α was selectively reactivated in an ER stress-independent manner in acquired KRASi-resistant tumors, restoring proteostasis. Oncogenic KRAS promoted IRE1α protein stability through extracellular signal-regulated kinase (ERK)-dependent phosphorylation of IRE1α, leading to IRE1α disassociation from 3-hydroxy-3-methylglutaryl reductase degradation (HRD1) E3-ligase. In KRASi-resistant tumors, both reactivated ERK and hyperactivated AKT restored IRE1α phosphorylation and stability. Suppression of IRE1α overcame resistance to KRASi. This study reveals a druggable mechanism that leads to proteostasis reprogramming and facilitates KRASi resistance.