Identification of Colorectal Cancer Cell Stemness from Single-Cell RNA Sequencing

Cancer stem cells (CSC) play a critical role in metastasis, relapse, and therapy resistance in colorectal cancer. While characterization of the normal lineage of cell development in the intestine has led to the identification of many genes involved in the induction and maintenance of pluripotency, recent studies suggest significant heterogeneity in CSC populations. Moreover, while many canonical colorectal cancer CSC marker genes have been identified, the ability to use these classical markers to annotate stemness at the single-cell level is limited. In this study, we performed single-cell RNA sequencing on a cohort of 6 primary colon, 9 liver metastatic tumors, and 11 normal (nontumor) controls to identify colorectal CSCs at the single-cell level. Finding poor alignment of the 11 genes most used to identify colorectal CSC, we instead extracted a single-cell stemness signature (SCS_sig) that robustly identified "gold-standard" colorectal CSCs that expressed all marker genes. Using this SCS_sig to quantify stemness, we found that while normal epithelial cells show a bimodal distribution, indicating distinct stem and differentiated states, in tumor epithelial cells stemness is a continuum, suggesting greater plasticity in these cells. The SCS_sig score was quite variable between different tumors, reflective of the known transcriptomic heterogeneity of CRC. Notably, patients with higher SCS_sig scores had significantly shorter disease-free survival time after curative intent surgical resection, suggesting stemness is associated with relapse.

IMPLICATIONS

This study reveals significant heterogeneity of expression of genes commonly used to identify colorectal CSCs, and identifies a novel stemness signature to identify these cells from scRNA-seq data.

Breast Implant Associated Anaplastic Large Cell Lymphoma: Evidence-Based Consensus Conference Statement From The American Association of Plastic Surgeons

BACKGROUND

In the absence of high-quality evidence, there is a need to provide guidelines and multidisciplinary consensus recommendations on Breast Implant-Associated Anaplastic Large Cell Lymphoma (BIA-ALCL). The purpose of this expert consensus conference was to evaluate the existing evidence regarding the diagnosis, and management of BIA-ALCL caused by textured implants. The aim is to provide evidence-based recommendations regarding the management and prevention of BIA-ALCL.

METHODS

A comprehensive search was conducted in the MEDLINE, Cochrane Library, and Embase databases, supplemented by manual searches of relevant English language articles and "related articles" sections. Studies focusing on breast surgery and lymphoma associated with breast implants were included for analysis. Meta-analyses were performed and reviewed by experts selected by the American Association of Plastic Surgeons by a Delphi consensus method.

RESULTS

840 articles between January 2011 and January 2023 were initially identified and screened. Full-text of 188 articles were assessed. An additional 43 articles were excluded for focus, and 145 articles were included in the synthesis of results, with 105 of them being case reports or case series. The analysis encompassed a comprehensive examination of the selected articles to determine the incidence, risk factors, clinical presentation, diagnostic approaches, and treatment modalities related to BIA-ALCL.

CONCLUSIONS

Plastic surgeons should be aware of the elevated risks by surface type, implement appropriate patient surveillance, and follow the recommendations outlined in this statement to ensure patient safety and optimize outcomes. Ongoing research on pathogenesis, genetic drivers, and preventative and prophylactic measures is crucial for improving patient care.

Efficacy and safety of autologous tumor-infiltrating lymphocytes in recurrent or refractory ovarian cancer, colorectal cancer, and pancreatic ductal adenocarcinoma

BACKGROUND

Tumor-infiltrating lymphocyte (TIL) therapy has shown efficacy in metastatic melanoma, non-small cell lung cancer, and other solid tumors. Our preclinical work demonstrated more robust CD8 predominant TIL production when agonistic anti-4-1BB and CD3 antibodies were used in early ex vivo TIL culture.

METHODS

Patients with treatment-refractory metastatic colorectal (CRC), pancreatic (PDAC) and ovarian (OVCA) cancers were eligible. Lymphodepleting chemotherapy was followed by infusion of ex vivo expanded TIL, manufactured at MD Anderson Cancer Center with IL-2 and agonistic stimulation of CD3 and 4-1BB (urelumab). Patients received up to six doses of high-dose IL-2 after TIL infusion. Primary endpoint was evaluation of objective response rate at 12 weeks using Response Evaluation Criteria in Solid Tumors version 1.1 with secondary endpoints including disease control rate (DCR), duration of response, progression-free survival (PFS), overall survival (OS), and safety.

RESULTS

17 patients underwent TIL harvest and 16 were treated on protocol (NCT03610490), including 8 CRC, 5 PDAC, and 3 OVCA patients. Median age was 57.5 (range 33-70) and 50% were females. Median number of lines of prior therapy was 2 (range 1-8). No responses were observed at 12 weeks. Ten subjects achieved at least one stable disease (SD) assessment for a DCR of 62.5% (95% CI 35.4% to 84.8%). Best response included prolonged SD in a patient with PDAC lasting 17 months. Median PFS and OS across cohorts were 2.53 months (95% CI 1.54 to 4.11) and 18.86 months (95% CI 4.86 to NR), respectively. Grade 3 or higher toxicities attributable to therapy were seen in 14 subjects (87.5%; 95% CI 61.7% to 98.4%). Infusion product analysis showed the presence of effector memory cells with high expression of CD39 irrespective of tumor type and low expression of checkpoint markers.

CONCLUSIONS

TIL manufactured with assistance of 4-1BB and CD3 agonism is feasible and treatment is associated with no new safety signals. While no responses were observed, a significant portion of patients achieved SD suggesting early/partial immunological effect. Further research is required to identify factors associated with resistance and functionally enhance T cells for a more effective therapy.

Radiographic response to neoadjuvant therapy in pleural mesothelioma should serve as a guide for patient selection for cytoreductive operations

Background

Malignant pleural mesothelioma (MPM) is associated with poor prognosis despite advances in multimodal therapeutic strategies. While patients with resectable disease may benefit from added survival with oncologic resection, patient selection for mesothelioma operations often relies on both objective and subjective evaluation metrics. We sought to evaluate factors associated with improved overall survival (OS) in patients with mesothelioma who underwent macroscopic complete resection (MCR).

Methods

Patients with MPM who received neoadjuvant therapy and underwent MCR were identified in a prospectively maintained departmental database. Clinicopathologic, blood-based, and radiographic variables were collected and included in a Cox regression analysis (CRA). Response to neoadjuvant therapy was characterized by a change in tumor thickness from pretherapy to preoperative scans using the modified RECIST criteria.

Results

In this study, 99 patients met the inclusion criteria. The median age of the included patients was 64.7 years, who were predominantly men, had smoking and asbestos exposure, and who received neoadjuvant therapy. The median change in tumor thickness following neoadjuvant therapy was -16.5% (interquartile range of -49.7% to +14.2%). CRA demonstrated reduced OS associated with non-epithelioid histology [hazard ratio (HR): 3.06, 95% confidence interval (CI): 1.62-5.78, p < 0.001] and a response to neoadjuvant therapy inferior to the median (HR: 2.70, CI: 1.55-4.72, p < 0.001). Patients who responded poorly (below median) to neoadjuvant therapy had lower median survival (15.8 months compared to 38.2 months, p < 0.001).

Conclusion

Poor response to neoadjuvant therapy in patients with MPM is associated with poor outcomes even following maximum surgical cytoreduction and should warrant a patient-centered discussion regarding goals of care and may therefore help guide further therapeutic decisions.

Tumor thickness in mesothelioma predicts differential response to neoadjuvant therapy and survival

OBJECTIVE

Neoadjuvant systemic therapy in resectable malignant pleural mesothelioma remains controversial and demonstrates variable responses. We sought to evaluate tumor thickness as a predictor of response to neoadjuvant therapy and as a prognostic marker for overall survival.

METHODS

Data from patients who underwent neoadjuvant therapy followed by cytoreductive surgery from 2002 to 2019 were reviewed. Baseline and postneoadjuvant therapy tumor thickness were measured on computed tomography. Radiological tumor response was categorized as progressive disease (≥20% increase), partial response (≥30% decrease), or stable disease (in between). Tumor response outcomes were modeled using logistic regression and multinomial regression models. Overall survival was evaluated based on tumor thickness and tumor response.

RESULTS

Of the 143 patients reviewed, 36 (25%) had progressive disease, 54 (38%) had stable disease, and 56 (39%) had partial response. The baseline tumor thickness of the progressive disease group (36 mm) was lower than in both stable disease and partial response groups (both 63 mm; P < .001). Both logistic regression and multinomial regression analyses demonstrated that thicker baseline tumor thickness was associated with decreased probability of progressive disease and increased probability of partial response. In a multivariable Cox model, thicker postneoadjuvant therapy tumor thickness was associated with worse overall survival (hazard ratio, 1.01, 95% confidence interval, 1.00-1.01, P = .008). The same trend was observed for thicker baseline tumor thickness (hazard ratio, 1.02, 95% confidence interval, 1.01-1.04, P = .008), and the risk was decreased in tumors with partial response (hazard ratio, 0.98, 95% confidence interval, 0.96-0.100, P = .014).

CONCLUSIONS

We present the first study demonstrating the relationship between baseline tumor thickness and differential radiographic response to neoadjuvant therapy and survival. Further studies are needed to validate tumor thickness as both a prognostic and predictive biomarker.

Phase II trial of neoadjuvant sitravatinib plus nivolumab in patients undergoing nephrectomy for locally advanced clear cell renal cell carcinoma

Sitravatinib is an immunomodulatory tyrosine kinase inhibitor that can augment responses when combined with programmed death-1 inhibitors such as nivolumab. We report a single-arm, interventional, phase 2 study of neoadjuvant sitravatinib in combination with nivolumab in patients with locally advanced clear cell renal cell carcinoma (ccRCC) prior to curative nephrectomy (NCT03680521). The primary endpoint was objective response rate (ORR) prior to surgery with a null hypothesis ORR = 5% and the alternative hypothesis set at ORR = 30%. Secondary endpoints were safety; pharmacokinetics (PK) of sitravatinib; immune effects, including changes in programmed cell death-ligand 1 expression; time-to-surgery; and disease-free survival (DFS). Twenty patients were evaluable for safety and 17 for efficacy. The ORR was 11.8%, and 24-month DFS probability was 88·0% (95% CI 61.0 to 97.0). There were no grade 4/5 treatment-related adverse events. Sitravatinib PK did not change following the addition of nivolumab. Correlative blood and tissue analyses showed changes in the tumour microenvironment resulting in an immunologically active tumour by the time of surgery (median time-to-surgery: 50 days). The primary endpoint of this study was not met as short-term neoadjuvant sitravatinib and nivolumab did not substantially increase ORR.

Phase II study of durvalumab (anti-PD-L1) and trametinib (MEKi) in microsatellite stable (MSS) metastatic colorectal cancer (mCRC)

Background

Monotherapy with immune checkpoint blockade is ineffective for patients (pts) with microsatellite stable (MSS) metastatic colorectal cancer (mCRC). This study investigates whether the combination of trametinib (T) with durvalumab (D) can alter the immune tumor microenvironment (TME) by successfully priming and activating T-cells.

Methods

Open-label, single-center, phase II trial with primary endpoint of immune-related response rate for combination of T+D in refractory MSS mCRC pts (NCT03428126). T is 2 mg/day orally starting 1 week prior to D, which is given 1500 mg intravenously every 4 weeks. Simon 2-stage design used to enroll 29 pts into first stage, requiring a response in two or more pts to proceed to stage 2. Tumor biopsies were collected at baseline (BL) and early on-treatment (OT) at week 4.

Results

Twenty nine treated pts include 48% females, median age 48 years (range 28–75), and median prior therapies 2 (range 1–5). No grade (G) 4 or 5 treatment-related adverse events (TRAE). The most common TRAE of any grade was acneiform rash, 17% being G3. One of 29 pts had confirmed partial response (PR) lasting 9.3 months (mo) for an overall response rate of 3.4%. Seven pts had stable disease (SD) and five pts (1 PR, 4 SD) demonstrated decrease in total carcinoembryonic antigen ng/mL (best percentage reduction: 94%, 95%, 42%, 34%, and 22%, respectively). Median progression-free survival was 3.2 mo (range 1.1–9.3 months). Three pts with both liver and lung metastases demonstrated discrepant responses in which clinical benefit was present in the lung metastases but not liver metastases. Comparison of BL and 4-week OT tumor tissue flow cytometry demonstrated no changes in T-cell infiltration but upregulation expression of PD-1 and Tim3 on CD8 T cells. However, expression of PD-1 and Tim3 as single markers and as coexpressed markers was observed to increase OT relative to BL (p=0.03, p=0.06 and p=0.06, respectively).

Conclusions

T+D demonstrated acceptable tolerability in pts with refractory MSS mCRC. The response rate in the first stage of the study did not meet efficacy criteria to proceed to the second stage. Specific site of metastatic disease may impact outcomes in novel immunotherapy combination trials.

Trial registration number

NCT03428126.

Single cell sequencing reveals trajectory of tumor-infiltrating lymphocyte states in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) has few effective treatments. Immunotherapy, an attractive alternative strategy, remains challenging with the lack of knowledge on the tumor-infiltrating lymphocyte (TIL) landscape in PDAC. To generate a reference of T-cell subpopulations, we profiled 80,000 T cells from 57 PDAC, 22 uninvolved/normal samples, and cultured TIL using single-cell transcriptomic and T-cell receptor analysis. These data revealed 20 cell states and heterogeneous distributions of TIL populations. The CD8+ TIL contained a putative transitional GZMK+ population based on TCR clonotype sharing, and cell-state trajectory analysis showed similarity to a GZMB+PRF1+ cytotoxic and a CXCL13+ dysfunctional population. Statistical analysis suggested that certain TIL states, such as dysfunctional and inhibitory populations, often occurred together. Finally, analysis of cultured TIL revealed that high-frequency clones from effector populations were preferentially expanded. These data provide a framework for understanding the PDAC TIL landscape for future TIL use in immunotherapy for PDAC.

Multi-modal molecular programs regulate melanoma cell state

Melanoma cells display distinct intrinsic phenotypic states. Here, we seek to characterize the molecular regulation of these states using multi-omic analyses of whole exome, transcriptome, microRNA, long non-coding RNA and DNA methylation data together with reverse-phase protein array data on a panel of 68 highly annotated early passage melanoma cell lines. We demonstrate that clearly defined cancer cell intrinsic transcriptomic programs are maintained in melanoma cells ex vivo and remain highly conserved within melanoma tumors, are associated with distinct immune features within tumors, and differentially correlate with checkpoint inhibitor and adoptive T cell therapy efficacy. Through integrative analyses we demonstrate highly complex multi-omic regulation of melanoma cell intrinsic programs that provide key insights into the molecular maintenance of phenotypic states. These findings have implications for cancer biology and the identification of new therapeutic strategies. Further, these deeply characterized cell lines will serve as an invaluable resource for future research in the field.

CRISPR-mediated TGFBR2 knockout renders human ovarian cancer tumor-infiltrating lymphocytes resistant to TGF-β signaling

Background

The correlation between elevated T-cell infiltration and improved survival of ovarian cancer (OvCa) patients suggests that endogenous tumor-infiltrating lymphocytes (TIL) possess some degree of antitumor activity that can be harnessed for OvCa immunotherapy. We previously optimized a protocol for ex vivo OvCa TIL expansion for adoptive cell therapy, which is now being tested in a clinical trial at our institution (NCT03610490). Building on this success, we embarked on genetic modification of OvCa TIL to overcome key immunosuppressive factors present in the tumor microenvironment. Here, we present the preclinical optimization of CRISPR/Cas9-mediated knockout of the TGF-β receptor 2 (TGFBR2) in patient-derived OvCa TIL.

Methods

OvCa TILs were generated from four patients’ tumor samples obtained at surgical resection and subjected to CRISPR/Cas9-mediated knockout of TGFBR2 before undergoing a rapid expansion protocol. TGFBR2-directed gRNAs were comprehensively evaluated for their TGFBR2 knockout efficiency and off-target activity. Furthermore, the impact of TGFBR2 knockout on TIL expansion, function, and downstream signaling was assayed.

Results

TGFBR2 knockout efficiencies ranging from 59±6% to 100%±0% were achieved using 5 gRNAs tested in four independent OvCa TIL samples. TGFBR2 knockout TIL were resistant to immunosuppressive TGF-β signaling as evidenced by a lack of SMAD phosphorylation, a lack of global transcriptional changes in response to TGF-β stimulation, equally strong secretion of proinflammatory cytokines in the presence and absence of TGF-β, and improved cytotoxicity in the presence of TGF-β. CRISPR-modification itself did not alter the ex vivo expansion efficiency, immunophenotype, nor the TCR clonal diversity of OvCa TIL. Importantly for clinical translation, comprehensive analysis of CRISPR off-target effects revealed no evidence of off-target activity for our top two TGFBR2-targeting gRNAs.

Conclusions

CRISPR/Cas9-mediated gene knockout is feasible and efficient in patient-derived OvCa TIL using clinically-scalable methods. We achieved efficient and specific TGFBR2 knockout, yielding an expanded OvCa TIL product that was resistant to the immunosuppressive effects of TGF-β. This study lays the groundwork for clinical translation of CRISPR-modified TIL, providing opportunities for engineering more potent TIL therapies not only for OvCa treatment, but for the treatment of other solid cancers as well.

Multiomics profiling and association with molecular and immune features in association with benefits from immunotherapy for patients with previously treated stage IV or recurrent squamous cell lung cancer from the phase III SWOG LungMAP S1400I trial

9046

Background: Immune checkpoint blockade (ICB) has become a standard pillar of treatment for lung cancer. However, only ̃20% of unselected patients can achieve durable clinical benefits. We performed immunogenomic profiling of tissue specimens from a randomized Phase III trial S1400I on metastatic lung squamous cell carcinoma (SCC) to evaluate if there were factors associated with better prognoses with ICB from single-agent versus combined targeting PD-1/CTLA-4 and evaluate if any differentiated between the treatments. Methods: We utilized FFPE tumor tissue submitted for Lung-MAP screening provided by the SWOG bank. SCC samples from 82 eligible patients treated with combined nivolumab+ipilimumab (N+I) or single agent nivolumab (N) were subjected to multiplex immunofluorescence (mIF, n = 82) and NanoString (ncounter PanCancer Immune Profiling Panel, n = 32). Cell density phenotypes (cells/mm2) were defined using image analysis of staining for cytokeratin, CD3, CD8, granzyme B, CD45RO, FOXP3, PD1, PD-L1, and CD68. Immunogenomic features were associated with response, PFS, and OS derived from data provided by the LungMap team to the CIDC portal. For statistical analyses, non-parametric tests were utilized to assess associations of cell phenotypes versus continuous or categorical variables, and log-rank test analysis was performed to identify cell phenotypes or genes correlated with survival. Results: In both arms higher densities of total CD3+CD45RO+ T cells ( P= 0.041), CD3+PD-1+ T cells ( P= 0.024) and CD3+CD8+PD-1 T cells in stroma ( P= 0.042) and CD3+CD8+GZMB+ T cells in the tumor compartment ( P= 0.011) were positively associated with PFS. In the N+I arm but not in the N arm, higher densities of CD3+CD8+GZMB+ T cells in the tumor compartment were associated with better PFS ( P= 0.015) and higher densities of stroma CD3+CD8-FOXP3+ T cells with worse OS. Spatial analysis showed that the presence of CD8+GZMB+ T cells close to malignant cells (median, ≤19.27 µm) was associated with better PFS ( P= 0.037) in N+I arm and cluster analysis showed low clustering of cells in TMB-high vs. TMB-low tumors (P < 0.01). Gene expression profiling demonstrated that myeloid infiltration, immune recruitment, and inflammation genes were associated with a positive clinical outcome ( P< 0.05). In both arms, BLNK, CD163, FCGR2A were associated with better OS ( P< 0.01), IRF1 and BLNK were associated with increased PFS ( P< 0.01). In the N+I arm but not in the N arm, we observed significantly higher CD45 immune cell scores, including CD8 T cells and neutrophils, in responders versus non-responders. Conclusions: Our findings suggest a potential advantage in PFS and OS with an increased presence of cytotoxic immune cells and genes associated with the recruitment and proliferation of these cell types before therapy.

A phase II multi-arm study to test the efficacy of oleclumab and durvalumab in specific sarcoma subtypes

TPS11594

Background: Anti-PD 1/PD-L1 blockade alone or in combination with anti-CTLA4 have yielded suboptimal results in most sarcoma subtypes. CD73, an ectonucleotidase, catalyzes the rate-limiting step for adenosine production in the extracellular space, which then aids tumors in evading immune recognition and destruction. Oleclumab, a monoclonal antibody (mAb) selectively binds and inhibits the activity of CD73, and preclinical data suggests additive activity with durvalumab, a mAb that blocks PD-L1. We designed a trial combining oleclumab and durvalumab in certain sarcoma subtypes, selected based on modest activity with anti-PDL-1 and intense staining with CD73 in the tumor microenvironment. Methods: This phase 2 study (NCT04668300) is enrolling patients with age ≥18 years with recurrent/metastatic angiosarcoma (cohort 1) or dedifferentiated liposarcoma (DLPS) (cohort 2) and ≥12 years with recurrent/metastatic osteosarcoma (cohort 3), who have received at least one prior systemic therapy but are checkpoint inhibitor naïve and have measurable disease. Each treatment cycle is 28 days with oleclumab administered at 3000 mg i.v. every 2 weeks x 5 doses, and then every 4 weeks and durvalumab administered at 1500 mg i.v every 4 weeks. Tumor assessments are based on RECIST 1.1 and immune-related response criteria (irRC) and performed at baseline, and every 8 weeks after start of therapy, with an additional scan at 12 weeks for confirmation of response. Planned sample size is ≤ 25 pts in each arm. The primary efficacy endpoint for cohorts 1 and 2 is response rate (RR) at 4 months (per RECIST 1.1). The primary efficacy endpoint for cohort 3 is event free survival (EFS) rate at 4 months. If there is a high probability that the RR4 months is unlikely to be at least 20% for cohorts 1 and 2 or the EFS4 months is unlikely to be at least 40% for cohort 3 then the accrual of the corresponding cohort will be halted. The cohorts will be monitored separately for both futility and toxicity in groups of 5 after a minimum of 10 patients have been enrolled in each cohort. Secondary endpoints for the study include safety, best RR by RECIST and irRC, median PFS, and OS. Core needle biopsies and blood samples are collected at baseline and early on-treatment (week 6). Fresh flow cytometry is being performed to assess changes in T-cell activation, proliferation, and function and CD73 expression in the membrane and cytoplasm is being assessed by immunohistochemistry. Localization of tumor-infiltrating lymphocytes and engagement of the PD-1/PDL1 axis is being assessed using multiplex immunofluorescence staining. As of Jan 30th, 2022, twenty-two patients have initiated study treatment, 3 in cohort 1, 12 in cohort 2, and 7 in cohort 3. Clinical trial information: NCT04668300.

Efficacy and safety of autologous expanded tumor infiltrating lymphocytes (TILs) in multiple solid tumors

2536

Background: TIL therapy has been used extensively in metastatic melanoma patients for many years, now with ongoing efforts to commercialize treatment. The efficacy of TIL outside of melanoma is largely unknown thus we designed and implemented a trial using TIL manufactured at a single academic center for treatment refractory metastatic colorectal (CRC), pancreas (PDAC) and ovarian (OVA) cancers. Methods: Patients with CRC, PDAC and OVA refractory to standard therapies with ECOG PS 0-1 and normal organ function were eligible for TIL harvest. Ex vivo TIL expansion and manufacturing was conducted at the MD Anderson TIL lab under conditions that included IL2 and 41BB stimulation (using urelumab). All patients received a lymphodepletion regimen consisting of cyclophosphamide 60mg/kg days -7 and -6 and fludarabine 25mg/m2 days -5 through day -1, followed by infusion of pooled ex-vivo expanded TIL. Patients received up to 6 doses of high dose IL-2 (600,000 IU/kg) after TIL infusion. The primary endpoint was evaluation of the objective response rate (ORR) using RECIST 1.1 criteria with secondary endpoints including disease control rate, duration of response, PFS, OS and safety. Results: A total of 17 patients underwent TIL harvest and 16 were treated on protocol; including 8 CRC, 5 PDAC and 3 OVA. Median age was 57.5 (range 33-70) and 50% were females. Median number of lines of prior therapy was 2 (range 1-8). Median number of TIL infused was 76 X 109 (range 20.3 x 109-150 x 109). Median doses of cyclophosphamide and fludarabine administered were 2 (range, 2-2) and 3 (range, 1-5), respectively. Median doses of IL-2 administered was 6 (range, 1-6). There were no responders. Best response included prolonged SD in a patient with PDAC lasting until 18 months. Grade 3 or higher toxicities attributable to therapy was seen in 14 subjects (87.5%; 95% CI: 61.7 – 98.4) with the majority of toxicities representing expected pancytopenia from lymphodepletion. Infusion product analysis showed the presence of effector memory cells with high expression of CD39 irrespective of tumor type. Early on-treatment biopsy of PDAC patient with prolonged SD showed presence of proliferating (KI67+) CD4+ and CD8+ TIL. Conclusions: Generation of TIL at a single academic center for CRC, PDAC and OVA is feasible and treatment is associated with no new safety signals. For these tumor types, further research is required to identify host factors associated with resistance to TIL therapy and optimize manufacturing processes to create more effective TIL cell therapy. Clinical trial information: NCT03610490.

2022 Practice Recommendation Updates From the World Consensus Conference on BIA-ALCL

BACKGROUND

Laboratory and clinical research on breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) is rapidly evolving. Changes in standard of care and insights into best practice were recently presented at the 3rd World Consensus Conference on BIA-ALCL.

OBJECTIVES

The authors sought to provide practice recommendations from a consensus of experts, supplemented with a literature review regarding epidemiology, etiology, pathogenesis, diagnosis, treatment, socio-psychological aspects, and international authority guidance.

METHODS

A literature search of all manuscripts between 1997 and August 2021 for the above areas of BIA-ALCL was conducted with the PubMed database. Manuscripts in different languages, on non-human subjects, and/or discussing conditions separate from BIA-ALCL were excluded. The study was conducted employing the Delphi process, gathering 18 experts panelists and utilizing email-based questionnaires to record the level of agreement with each statement by applying a 5-point Likert Scale. Median response, interquartile range, and comments were employed to accept, reject, or revise each statement.

RESULTS

The literature search initially yielded 764 manuscripts, of which 405 were discarded. From the remaining 359, only 218 were included in the review and utilized to prepare 36 statements subdivided into 5 sections. After 1 round, panelists agreed on all criteria.

CONCLUSIONS

BIA-ALCL is uncommon and still largely underreported. Mandatory implant registries and actions by regulatory authorities are needed to better understand disease epidemiology and address initial lymphomagenesis and progression. Deviation from current diagnosis and treatment protocols can lead to disease recurrence, and research on breast implant risk factors provide insight to etiology.

LEVEL OF EVIDENCE: 4

Hallmarks of Resistance to Immune-Checkpoint Inhibitors

Immune-checkpoint inhibitors (ICI), although revolutionary in improving long-term survival outcomes, are mostly effective in patients with immune-responsive tumors. Most patients with cancer either do not respond to ICIs at all or experience disease progression after an initial period of response. Treatment resistance to ICIs remains a major challenge and defines the biggest unmet medical need in oncology worldwide. In a collaborative workshop, thought leaders from academic, biopharma, and nonprofit sectors convened to outline a resistance framework to support and guide future immune-resistance research. Here, we explore the initial part of our effort by collating seminal discoveries through the lens of known biological processes. We highlight eight biological processes and refer to them as immune resistance nodes. We examine the seminal discoveries that define each immune resistance node and pose critical questions, which, if answered, would greatly expand our notion of immune resistance. Ultimately, the expansion and application of this work calls for the integration of multiomic high-dimensional analyses from patient-level data to produce a map of resistance phenotypes that can be utilized to guide effective drug development and improved patient outcomes.

Loss of Rnf43 Accelerates Kras-Mediated Neoplasia and Remodels the Tumor Immune Microenvironment in Pancreatic Adenocarcinoma

BACKGROUND & AIMS

RNF43 is an E3 ubiquitin ligase that is recurrently mutated in pancreatic ductal adenocarcinoma (PDAC) and precursor cystic neoplasms of the pancreas. The impact of RNF43 mutations on PDAC is poorly understood and autochthonous models have not been characterized sufficiently. In this study, we describe a genetically engineered mouse model (GEMM) of PDAC with conditional expression of oncogenic Kras and deletion of the catalytic domain of Rnf43 in exocrine cells.

METHODS

We generated Ptf1a-Cre;LSL-KrasG12D;Rnf43flox/flox (KRC) and Ptf1a-Cre; LSL-KrasG12D (KC) mice and animal survival was assessed. KRC mice were sacrificed at 2 months, 4 months, and at moribund status followed by analysis of pancreata by single-cell RNA sequencing. Comparative analyses between moribund KRC and a moribund Kras/Tp53-driven PDAC GEMM (KPC) was performed. Cell lines were isolated from KRC and KC tumors and interrogated by cytokine array analyses, ATAC sequencing, and in vitro drug assays. KRC GEMMs were also treated with an anti-CTLA4 neutralizing antibody with treatment response measured by magnetic response imaging.

RESULTS

We demonstrate that KRC mice display a marked increase in incidence of high-grade cystic lesions of the pancreas and PDAC compared with KC. Importantly, KRC mice have a significantly decreased survival compared with KC mice. Using single-cell RNA sequencing, we demonstrated that KRC tumor progression is accompanied by a decrease in macrophages, as well as an increase in T and B lymphocytes, with evidence of increased immune checkpoint molecule expression and affinity maturation, respectively. This was in stark contrast to the tumor immune microenvironment observed in the KPC PDAC GEMM. Furthermore, expression of the chemokine CXCL5 was found to be specifically decreased in KRC cancer cells by means of epigenetic regulation and emerged as a putative candidate for mediating the unique KRC immune landscape.

CONCLUSIONS

The KRC GEMM establishes RNF43 as a bona fide tumor suppressor gene in PDAC. This GEMM features a markedly different immune microenvironment compared with previously reported PDAC GEMMs and puts forth a rationale for an immunotherapy approach in this subset of PDAC cases.

Combined IL-2, agonistic CD3 and 4-1BB stimulation preserve clonotype hierarchy in propagated non-small cell lung cancer tumor-infiltrating lymphocytes

Background

Adoptive cell transfer (ACT) of tumor-infiltrating lymphocytes (TIL) yielded clinical benefit in patients with checkpoint blockade immunotherapy-refractory non-small cell lung cancer (NSCLC) prompting a renewed interest in TIL-ACT. This preclinical study explores the feasibility of producing a NSCLC TIL product with sufficient numbers and enhanced attributes using an improved culture method.

Methods

TIL from resected NSCLC tumors were initially cultured using (1) the traditional method using interleukin (IL)-2 alone in 24-well plates (TIL 1.0) or (2) IL-2 in combination with agonistic antibodies against CD3 and 4-1BB (Urelumab) in a G-Rex flask (TIL 3.0). TIL subsequently underwent a rapid expansion protocol (REP) with anti-CD3. Before and after the REP, expanded TIL were phenotyped and the complementarity-determining region 3 β variable region of the T-cell receptor (TCR) was sequenced to assess the T-cell repertoire.

Results

TIL 3.0 robustly expanded NSCLC TIL while enriching for CD8⁺ TIL in a shorter manufacturing time when compared with the traditional TIL 1.0 method, achieving a higher success rate and producing 5.3-fold more TIL per successful expansion. The higher proliferative capacity and CD8 content of TIL 3.0 was also observed after the REP. Both steps of expansion did not terminally differentiate/exhaust the TIL but a lesser differentiated population was observed after the first step. TIL initially expanded with the 3.0 method exhibited higher breadth of clonotypes than TIL 1.0 corresponding to a higher repertoire homology with the original tumor, including a higher proportion of the top 10 most prevalent clones from the tumor. TIL 3.0 also retained a higher proportion of putative tumor-specific TCR when compared with TIL 1.0. Numerical expansion of TIL in a REP was found to perturb the clonal hierarchy and lessen the proportion of putative tumor-specific TIL from the TIL 3.0 process.

Conclusions

We report the feasibility of robustly expanding a T-cell repertoire recapitulating the clonal hierarchy of the T cells in the NSCLC tumor, including a large number of putative tumor-specific TIL clones, using the TIL 3.0 methodology. If scaled up and employed as a sole expansion platform, the robustness and speed of TIL 3.0 may facilitate the testing of TIL-ACT approaches in NSCLC.

Surgical approach does not influence changes in circulating immune cell populations following lung cancer resection

INTRODUCTION

The multimodal management of operable non-small cell lung cancer (NSCLC) continues to evolve rapidly. The immune milieu allowing for immunotherapeutic benefit can be affected by multiple parameters including clinicopathologic and genetic. Surgery induced physiological changes has received attention for modulating and affecting post-operative oncotaxis and immunosuppression. Here, we sought to investigate how surgical stress influences phenotype of peripheral blood mononuclear cells (PBMCs) in patients with NSCLC who underwent lobectomy.

METHODS

Blood was prospectively collected from patients with Stage IA-IIIA NSCLC undergoing lung resection between 2016 and 2018. Samples were obtained pre-operatively, 24 h and 4 weeks after surgery. PBMCs were isolated and subject to high-dimensional flow cytometry, analyzing a total of 115 cell populations with a focus on myeloid cells, T cell activation, and T cell trafficking. We further evaluated how surgical approach influenced post-operative PBMC changes, whether the operation was conducted in an open fashion with thoracotomy, or with minimally invasive Video Assisted Thoracoscopic Surgery (VATS).

RESULTS

A total of 76 patients met the inclusion criteria (Open n = 55, VATS n = 21). Surgical resection coincided with a decrease in T lymphocyte populations, including total CD3+ T cells, CD8+ T cells, and T effector memory cells, as well as an increase in monocytic myeloid-derived suppressor cells (mMDSC). Post-operative changes in PBMC populations were resolved after 4 weeks. Surgical-induced changes in immune populations were equivalent in patients undergoing open thoracotomy and VATS.

DISCUSSION

Surgical stress resulted in transient reduction in T cells and T effector memory cells, and increase of mMDSC following resection in NSCLC patients. The immune profile modulation was similar regardless of surgical approach. These findings suggest that surgical approach does not seem to affect mononuclear cell lines obtained from peripheral blood. Thus, the decision regarding surgical approach should be patient centered, rather than based on post-operative treatment response optimization.

Engineered T-cell Receptor T Cells for Cancer Immunotherapy

Engineering immune cells to target cancer is a rapidly advancing technology. The first commercial products, chimeric-antigen receptor (CAR) T cells, are now approved for hematologic malignancies. However, solid tumors pose a greater challenge for cellular therapy, in part because suitable cancer-specific antigens are more difficult to identify and surrounding healthy tissues are harder to avoid. In addition, impaired trafficking of immune cells to solid tumors, the harsh immune-inhibitory microenvironment, and variable antigen density and presentation help tumors evade immune cells targeting cancer-specific antigens. To overcome these obstacles, T cells are being engineered to express defined T-cell receptors (TCR). Given that TCRs target intracellular peptides expressed on tumor MHC molecules, this provides an expanded pool of potential targetable tumor-specific antigens relative to the cell-surface antigens that are targeted by CAR T cells. The affinity of TCR T cells can be tuned to allow for better tumor recognition, even with varying levels of antigen presentation on the tumor and surrounding healthy tissue. Further enhancements to TCR T cells include improved platforms that enable more robust cell expansion and persistence; coadministration of small molecules that enhance tumor recognition and immune activation; and coexpression of cytokine-producing moieties, activating coreceptors, or mediators that relieve checkpoint blockade. Early-phase clinical trials pose logistical challenges involving production, large-scale manufacturing, and more. The challenges and obstacles to successful TCR T-cell therapy, and ways to overcome these and improve anticancer activity and efficacy, are discussed herein.

Elucidation of Tumor-Stromal Heterogeneity and the Ligand-Receptor Interactome by Single-Cell Transcriptomics in Real-world Pancreatic Cancer Biopsies

PURPOSE

Precision medicine approaches in pancreatic ductal adenocarcinoma (PDAC) are imperative for improving disease outcomes. With molecular subtypes of PDAC gaining relevance in the context of therapeutic stratification, the ability to characterize heterogeneity of cancer-specific gene expression patterns is of great interest. In addition, understanding patterns of immune evasion within PDAC is of importance as novel immunotherapeutic strategies are developed.

EXPERIMENTAL DESIGN

Single-cell RNA sequencing (scRNA-seq) is readily applicable to limited biopsies from human primary and metastatic PDAC and identifies most cancers as being an admixture of previously described epithelial transcriptomic subtypes.

RESULTS

Integrative analyses of our data provide an in-depth characterization of the heterogeneity within the tumor microenvironment, including cancer-associated fibroblast subclasses, and predicts for a multitude of ligand-receptor interactions, revealing potential targets for immunotherapy approaches.

CONCLUSIONS

Our analysis demonstrates that the use of de novo biopsies from patients with PDAC paired with scRNA-seq may facilitate therapeutic prediction from limited biopsy samples.

Neutrophil expansion defines an immunoinhibitory peripheral and intratumoral inflammatory milieu in resected non-small cell lung cancer: a descriptive analysis of a prospectively immunoprofiled cohort

Background

The biological underpinnings of the prognostic and predictive significance of a relative neutrophilia in patients with non-small lung cancer (NSCLC) are undefined. We sought to comprehensively examine the relationships between circulating and intratumoral neutrophil populations and features of the immune contexture in patients undergoing NSCLC resection.

Methods

Preoperative soluble cytokine and angiogenic factors; tumor multiplex immunofluorescence; RNA, whole exome, and T-cell receptor sequencing; and flow cytometry were analyzed for relationships with populations of circulating (from complete blood counts) and intratumoral neutrophils (transcriptional signatures) in a prospectively enrolled resected NSCLC cohort (n=66). In a historical cohort (n=1524), preoperative circulating neutrophil and lymphocyte counts were analyzed for associations with overall survival (OS).

Results

Circulating neutrophil populations were positively correlated with increased tumor burden, and surgical tumor resection was followed by a subsequent reduction in peripheral neutrophil counts. Expansion of the circulating neutrophil compartment was associated with increased levels of pro-granulopoietic (IL-1β, IL-17A, TNFα, IL-6) and T_H2-associated (IL-5, IL-13) cytokines. Tumors with high intratumoral neutrophil burden were marked by a blunted T-cell response characterized by reduced expression of cytotoxic T-cell genes (CD8A, CD8B, GZMA, GZMB), decreased CD3⁺CD8⁺ cell infiltration, and diminished expression of IFNγ-related genes. The associations between increased intratumoral neutrophil burden and reduced CD3⁺CD8⁺ infiltration persisted after adjustment for tumor size, histology, mutational burden, and PD-L1 expression. In 1524 patients, elevated preoperative circulating neutrophil count was independently associated with worse OS (main effect HR 1.82, 95% CI 1.24 to 2.68, p=0.002).

Conclusions

Our findings demonstrate that neutrophil expansion reflects protumorigenic and immunosuppressive processes that manifest as worse OS in patients undergoing NSCLC resection. These results justify further investigation of therapeutic strategies targeting neutrophil-associated immune evasion.

Abstract 1670: Circulating biomarkers are associated with recurrence following complete resection of non-small cell lung cancer

Background: We have previously demonstrated that the presence of a proinflammatory peripheral cytokine milieu correlates with high levels of circulating neutrophils at the time of surgery and reduced overall survival and recurrence-free survival. In this study, we hypothesized that functional immune features or states in circulation may indicate early tumor recurrence when assessed longitudinally. We also investigated whether potential deficiencies in peripheral immune functionality at the time of lung cancer resection could identify correlates with subsequent outcome.

Methods: We performed flow cytometry and luminex profiling of blood samples collected from patients with stage I-IIIA resected NSCLC (n=150) and enrolled on the Immunogenomic profiling of NSCLC (ICON) prospective protocol. Patient characteristics include 75 adenocarcinomas, 30 squamous and 12 mixed or other histologies. Only patients who underwent primary cancer resection without neoadjuvant therapy were included. At a median follow up of 18.2 months, 37 patients had disease recurrence. Blood was collected at the time of primary lung cancer resection, at 4 weeks, and 4 months thereafter with PBMCs utilized for flow cytometry and plasma for cytokine assessment. Changes in cytokines were assessed by normalizing to baseline levels.

Results: Larger tumors as well as advanced clinical and pathological stages were associated with higher frequencies of proliferating Ki67+CD4+ and Ki67+CD8+ T cells in circulation at time of resection, suggesting an activated circulating immune response. We identified novel strong correlations in the plasma between soluble BTLA and Tim3 (r= 0.87, p=1.74e-140), PD1 and CD80 (r=0.72, p=6.41e-74) and moderate correlations between soluble PD1 and PDL1 (r=0.39, p=8.41e-18). Efforts are ongoing to determine the association of specific circulating immune states with the presence of these soluble receptors. CD8+Tim3+ T cells (FC=5.2%, p=0.028) and CTLA4+NK cells (FC=47.7%, p=0.002) as well as CTLA4+Tregs (FC=25.2%, p=0.05) were found to be increased in circulation at pre-recurrence time points (either 4 weeks or 4 months) relative to resection. This suggests the emergence of a suppressive cell type as well as induction of specific checkpoint receptors on effector cells that correlate with tumor recurrence. Finally, we identified a cytokine signature associated with recurrence by testing three sets within the ICON cohort with a training set AUC = 0.76 and the test set AUC=0.72, which was validated in a third set of patients yielding an AUC = 0.76.

Conclusions: We identified circulating immune features associated with initial tumor size and overall stage as well as unique associations among soluble proteins. Increased presence of potentially inhibited or suppressed CD8+ T cells and NK cells as well as Tregs are suggestive of mechanisms of immune suppression relative to tumor recurrence.

Citation Format: Younghee Lee, Daniel McGrail, Hai Tran, Mayra E. Vasquez, Carlos Ramos, Alexandre Reuben, Ara A. Vaporciyan, Annikka Weissferdt, Chantale Bernatchez, Tina Cascone, Ignacio I. Wistuba, Jianjun Zhang, John Heymach, Marcelo V. Negrao, Don L. Gibbons, Boris Sepesi, Cara L. Haymaker. Circulating biomarkers are associated with recurrence following complete resection of non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1670.

Pulmonary resection for tissue harvest in adoptive tumor-infiltrating lymphocyte therapy: Safety and feasibility

BACKGROUND AND OBJECTIVES

Adoptive T-cell therapies (ACTs) using expansion of tumor-infiltrating lymphocyte (TIL) populations are of great interest for advanced malignancies, with promising response rates in trial settings. However, postoperative outcomes following pulmonary TIL harvest have not been widely documented, and surgeons may be hesitant to operate in the setting of widespread disease.

METHODS

Patients who underwent pulmonary TIL harvest were identified, and postoperative outcomes were studied, including pulmonary, cardiovascular, infectious, and wound complications.

RESULTS

83 patients met inclusion criteria. Pulmonary TIL harvest was undertaken primarily via a thoracoscopy with a median operative blood loss and duration of 30 ml and 65 min, respectively. The median length of stay was 2 days. Postoperative events were rare, occurring in only five (6%) patients, including two discharged with a chest tube, one discharged with oxygen, one episode of urinary retention, and one blood transfusion. No reoperations occurred. The median time from TIL harvest to ACT infusion was 37 days.

CONCLUSIONS

Pulmonary TIL harvest is safe and feasible, without major postoperative events in our cohort. All patients were able to receive intended ACT infusion without delays. Therefore, thoracic surgeons should actively participate in ongoing ACT trials and aggressively seek to enroll patients on these protocols.

Randomized phase II trial of lymphodepletion plus adoptive cell transfer of tumor-infiltrating lymphocytes, with or without dendritic cell vaccination, in patients with metastatic melanoma

BACKGROUND

The adoptive transfer of tumor-infiltrating lymphocytes (TIL) has demonstrated robust efficacy in metastatic melanoma patients. Tumor antigen-loaded dendritic cells (DCs) are believed to optimally activate antigen-specific T lymphocytes. We hypothesized that the combined transfer of TIL, containing a melanoma antigen recognized by T cells 1 (MART-1) specific population, with MART-1-pulsed DC will result in enhanced proliferation and prolonged survival of transferred MART-1 specific T cells in vivo ultimately leading to improved clinical responses.

DESIGN

We tested the combination of TIL and DC in a phase II clinical trial of patients with advanced stage IV melanoma. HLA-A0201 patients whose early TIL cultures demonstrated reactivity to MART-1 peptide were randomly assigned to receive TIL alone or TIL +DC pulsed with MART-1 peptide. The primary endpoint was to evaluate the persistence of MART-1 TIL in the two arms. Secondary endpoints were to evaluate clinical response and survival.

RESULTS

Ten patients were given TIL alone while eight patients received TIL+DC vaccine. Infused MART-1 reactive CD8⁺ TIL were tracked in the blood over time by flow cytometry and results show good persistence in both arms, with no difference in the persistence of MART-1 between the two arms. The objective response rate was 30% (3/10) in the TIL arm and 50% (4/8) in the TIL+DC arm. All treatments were well tolerated.

CONCLUSIONS

The combination of TIL +DC showed no difference in the persistence of MART-1 TIL compared with TIL therapy alone. Although more patients showed a clinical response to TIL+DC therapy, this study was not powered to resolve differences between groups.

TRIAL REGISTRATION NUMBER

NCT00338377.

Intrathecal (IT) and intravenous (IV) nivolumab (N) for metastatic melanoma (MM) patients (pts) with leptomeningeal disease (LMD)

9519

Background: MM pts with LMD have a dismal prognosis, with median overall survival (OS) < 3 months, no approved therapies and extremely limited clinical trial options. We previously reported initial safety findings from an open label, single arm, single center phase I/IB trial (NCT03025256), in which IT and IV N were well tolerated, without any CNS-specific or unexpected toxicity. Here we report an update on safety and maximum tolerated dose (MTD) for all patients enrolled, and efficacy for the completed dose cohorts. Methods: MM patients aged >18 with evidence of LMD by MRI and/or CSF cytology, ECOG PS ≤2 were treated with IT and IV N. Dexamethasone ≤4mg/daily and concurrent BRAF/MEK inhibitor(i) treatment was allowed. For cycle 1, IT N was administered via intraventricular reservoir on day (D)1. For subsequent cycles (every 14 days), pts received IT N on D1, followed by IV N 240 mg on D2. IT N doses evaluated were 5, 10, 20 mg and 50 mg. Blood and CSF were collected at multiple time points for translational research. The primary objectives of this first-in-human study were to determine the safety and MTD of IT N given with IV N in MM pts with LMD. Bayesian mTPI methodology was used to define the MTD. Results: To date, 23 pts have been treated: two at 5, three at 10, fourteen at 20 mg and four at 50 mg IT N. Median age at LMD diagnosis was 42 (28-73); 12 pts are male. All pts had radiographic evidence of LMD and neurological symptoms; 14 pts had positive CSF cytology at baseline. 21 pts received prior therapies for their metastatic melanoma: anti-PD1 (n = 19), BRAFi/MEKi (n = 14), chemo (n = 2), IT IL2 (n = 4) other (n = 2). 19 pts had prior XRT, including whole brain RT (n = 7). Two pts were treatment-naïve. The median number of IT N doses was five (1- 66). The combination regimen was well tolerated by all evaluable pts (n=23), with only five pts (22%) experiencing gr 3 AEs, and no reported gr 4 or 5 toxicities. Nausea (30%), diarrhea (26%), and rash (22%) were the most common AEs. Eight pts (23%) experienced AEs after IT N administration, all gr 1. Initial efficacy analysis included only pts (n=19) treated with first three dose levels (5-20mg). Median follow-up for these pts is 4.5 months (mos) (1.1, 31.5 mos) and median OS is 63 % at 3 mos, 42 % at 6 mos and 30% at 12 mos. Conclusions: The trial demonstrates the feasibility and safety of IT administration of modern immunotherapy for MM pts with LMD. No unexpected systemic or neurological toxicity was observed with 20mg IT N. 2 additional patients are required to complete the 50mg IT N cohort. OS rates at 6 and 12 mos are encouraging and support further evaluation of IT administration of immunotherapy agents for pts with MM and LMD. Final presentation will include results of LMD for all dose cohorts, composite response assessment and comparative analysis of longitudinal CSF samples to assess immunologic effects. Clinical trial information: NCT03025256.

Comprehensive genomic profiling of malignant peritoneal mesothelioma (MPeM) reveals key genomic alterations (GAs) distinct from malignant pleural mesothelioma (MPM)

8557

Background: MPeM is a rare and aggressive cancer with very limited treatment options. Lack of dedicated research has impeded improvements in outcomes. Defining prevalent GAs is a critical unmet need for use of targeted therapies in these patients. Although MPeM is notably distinct from MPM vis-à-vis epidemiologic and clinical attributes, the genomic underpinings of these differences have yet to be established. We aimed at describing a comprehensive genomic profile (CGP) of MPeM in comparison to MPM. Methods: We performed a retrospective comparative analysis between 89 patients with MPeM and 241 patients with MPM (N = 330) who underwent CGP using CLIA certified next-generation sequencing assays. The cohort was generated using mesothelioma patients at MD Anderson Cancer Center (N = 223) and supplemented by additional mesothelioma patients (N = 107) from a publicly available database from Memorial Sloan Kettering Cancer Center, the MSK-IMPACT database. Essential clinicopathological variables were collected. Descriptive statistics, Fisher’s exact and Mann-Whitney tests were used for comparison. Kaplan-meier method and log rank tests were used for overall survival (OS) estimates. Results: MPeM cohort (vs. MPM) had more women (54% vs. 31%, P < 0.001) and younger age at diagnosis (56 vs. 69 years, P < 0.001). Histology was epithelioid, biphasic and sarcomatoid in 86%, 7% and 7% cases, a distribution similar to MPM cohort. At least 1 GA was found in 64 (72% vs. 82% in MPM, P = 0.044) of MPeM patients with a median of 1 (range 1 – 12) (vs. a median of 2, range 1 – 24, P < 0.001) GA per patient. A significantly lower proportion of MPeM patients had ≥ 3 mutations (14% vs. 26%, OR 2.1, P = 0.028) per patient. The most frequent mutations were present in the following genes: TP53 (24%), BAP1 (16%), NF2 (15%), MET (9%) and TRAF7, KIT and PIK3CA (each 6%). MPeM patients harbored more mutations in MET (9% vs. < 1%, P < 0.001) and TRAF7 (6% vs. < 1%, P = 0.02) but fewer mutations in BAP1 (16% vs. 32%, P = 0.003) and CDKN2B (0% vs. 5%, P = 0.041). The most common copy number variations (CNVs: amplifications or deletions) were seen in BAP1, MCL1, SETD2, WT1 (each 2%) and AURKA (1%) genes. Among genes with CNVs, MPeM had a lower rate of deletions in CDKN2A (1% vs. 6%, P = 0.040). Among more common GAs, only BAP1 mutations appeared to be associated with poor OS (45.7 vs. 127.1 months, HR 2.5, 95%CI: 0.6 – 10.1, P = 0.050) in patients with MPeM. Conclusions: In this large cohort with CGP, we identified potential molecular drivers in MPeM and demonstrated key genomic differences between MPeM and MPM. MPeM is frequently driven by GAs involved in cell cycle control, a potentially targetable pathway. Despite this insight from CGP, a large subset of patients do not have actionable GAs and for these patients, further collaborative trans-“omic” research efforts are needed to advance potential therapeutic options.

Extrapleural Pneumonectomy versus Pleurectomy/Decortication for Malignant Pleural Mesothelioma

BACKGROUND

Whether extrapleural pneumonectomy (EPP) or extended pleurectomy/decortication (P/D) is the optimal resection for malignant pleural mesothelioma (MPM) remains controversial. We therefore compared perioperative outcomes and long-term survival of patients who underwent EPP vs P/D.

METHODS

Patients with the diagnosis of MPM who underwent either EPP or P/D from 2000 to 2019 were identified from our departmental database. Propensity score matching was performed to minimize potential confounders for EPP or P/D. Survival analysis was performed by the Kaplan-Meier method and Cox multivariable analysis.

RESULTS

Of 282 patients, 187 (66%) underwent EPP and 95 (34%) P/D. Even with propensity score matching, perioperative mortality was significantly higher for EPP than for P/D (11% vs. 0%; P=0.031), when adjusted for perioperative mortality, median overall survival between EPP and P/D was 15 vs. 22 months, respectively (P=0.276). Cox multivariable analysis for the matched cohort identified epithelioid histology (hazard ratio [HR], 0.56; P=0.029), macroscopic complete resection (HR, 0.41; P=0.004), adjuvant radiation therapy (HR, 0.57; P=0.019), and more recent operative years (HR, 0.93; P=0.011)-but not P/D-to be associated with better survival. Asbestos exposure (HR, 2.35; P=0.003) and pathological nodal disease (HR, 1.61; P=0.048) were associated with worse survival.

CONCLUSIONS

In a multimodality treatment setting, P/D and EPP had comparable long-term oncological outcomes, although P/D had much lower perioperative mortality. The goal of surgical cytoreduction should be macroscopic complete resection achieved by the safest operation a patient can tolerate.

A phase II study of sitravatinib (Sitra) in combination with nivolumab (Nivo) in patients (Pts) undergoing nephrectomy for locally-advanced clear cell renal cell carcinoma (accRCC)

312

Background: Sitra is a spectrum-selective receptor tyrosine kinase inhibitor (TKI) that targets TAM receptors (TYRO3, AXL, MERTK), VEGFR2, c-Kit, and MET. These receptors regulate several immune suppressive cell types in the tumor microenvironment, including M2-polarized macrophages, MDSCs, and T regulatory cells, which are implicated in resistance to checkpoint inhibitors. ccRCC is characterized by upregulation of VEGF and overexpression of MET and AXL. Sitra may combine effectively with immune checkpoint inhibition to augment antitumor activity in ccRCC. About 39% of patients with accRCC who receive surgery with curative intent relapse representing an unmet need in this setting. Together these data support the evaluation of neoadjuvant sitra with nivo in accRCC. Methods: This phase II study (NCT03680521) evaluated sitra and nivo in pts with locally- advanced ccRCC who were candidates for curative nephrectomy. Single-agent sitra (120 mg) was administered daily (QD) for 2 weeks, with nivo (240 mg intravenously Q2W) added to sitra for 4-6 weeks. A plan for potential dose de-escalation was implemented using a modified toxicity probability interval method with a maximum toxicity of 20% at the tolerated dose. Pts underwent pathology/tissue evaluation at 3 timepoints: biopsy prior to treatment, biopsy prior to the addition of nivo, and nephrectomy specimen evaluation at time of nephrectomy. The primary endpoint was objective response (RECIST 1.1); secondary endpoints included safety, PK, and correlative immune effects (selected protein and gene expression and immune cell populations). Results: A total of 20 pts were evaluated for safety (95% had T3 or higher stage tumors, 65% with baseline hypertension). Dose-limiting toxicities (DLTs) led to a dose de-escalation, resulting in 7 pts treated at 120 mg QD sitra and 13 pts treated at 80 mg QD. DLTs included grade 3 (Gr3) hypertension (n=6); deep vein thrombosis and pulmonary embolism (Gr3) were observed in 1 additional pt. Median duration of sitra treatment was 6.3 weeks at the 80 mg dose and 7.1 weeks at the 120 mg dose. With a median follow-up of 9.4 months after initiation of systemic therapy, no pts have relapsed. In 17 pts evaluable for efficacy, the investigator-assessed confirmed ORR was 11.8%, including 2 PRs (33.3% ORR in pts who received 120 mg sitra). No pts experienced progressive disease while on therapy. Median DFS was not reached. There was 1 delayed surgery due to nivo-related thyroiditis that resolved. Reported TRAEs: Gr1/Gr2 in 55% of pts (dysphonia 50%, fatigue 45%, diarrhea 40%, hypertension 30%, increased ALT 30%), Gr3 in 45% of pts (hypertension 30%). There were no Gr4/Gr5 TRAEs. Correlative blood and tissue analyses will be presented. Conclusions: The combination of sitra and nivo is clinically active with a manageable safety profile as a neoadjuvant therapy for accRCC. Clinical trial information: NCT03680521 .

T-cell agonists in cancer immunotherapy

Cancer cells can evade immune surveillance in the body. However, immune checkpoint inhibitors can interrupt this evasion and enhance the antitumor activity of T cells. Other mechanisms for promoting antitumor T-cell function are the targeting of costimulatory molecules expressed on the surface of T cells, such as 4-1BB, OX40, inducible T-cell costimulator and glucocorticoid-induced tumor necrosis factor receptor. In addition, CD40 targets the modulation of the activation of antigen-presenting cells, which ultimately leads to T-cell activation. Agonists of these costimulatory molecules have demonstrated promising results in preclinical and early-phase trials and are now being tested in ongoing clinical trials. In addition, researchers are conducting trials of combinations of such immune modulators with checkpoint blockade, radiotherapy and cytotoxic chemotherapeutic drugs in patients with advanced tumors. This review gives a comprehensive picture of the current knowledge of T-cell agonists based on their use in recent and ongoing clinical trials.

Abstract PR03: Nongenomic BAP1 aberrancy drives highly aggressive cutaneous melanoma phenotype

The purpose of this study was to determine the role of BAP1 levels in cutaneous melanoma (CM). BAP1 is a tumor suppressor in which loss of heterozygosity (LOH) from mutation and copy number alteration is well described in germline and somatic cancers. Although BAP1 genomic alterations in CM are extremely rare (2% of 665 samples from 5 datasets), marked variability in BAP1 expression is observed in CM. We show that low nuclear BAP1 levels portend a significantly worse clinical outcome in stage III CM (n=37, log rank p ≤0.01 for both overall survival and progression-free survival). Gene Set Enrichment Analysis (GSEA) revealed low BAP1 expression to be most highly ranked with an increased epithelial–mesenchymal transition (EMT) gene expression profile in CM tumors (n=379, FDR q = 1.34E-26) and cell lines (n=53, FDR q = 2.86E-116). We identify the expression of ZEB1, a master regulator of EMT, to be significantly associated with low BAP1 expression in CM tumors and cell lines (p= 1.5E-04 and 3.3E-05, respectively). Analysis of the BAP1 promoter indicates three canonical ZEB1 binding sites. Functional experiments show ZEB1 to bind to the BAP1 promoter, and luciferase activity assays indicate that ZEB1 acts as a transcriptional suppressor of BAP1 expression with differential utilization of the promoter binding sites. Targeted reduction of endogenous ZEB1 caused increased BAP1 levels, while targeted reduction of BAP1 did not modulate ZEB1 levels, consistent with ZEB1 having a suppressive effect on BAP1. Phenotypically, targeted reduction of BAP1 in CM cells resulted in a switch from a more differentiated, melanocytic state, to a less differentiated, more migratory and invasive phenotype. Extinguishing melanocyte-specific BAP1 in mice with a BRAF V600E mutant genetic background resulted in the emergence of primary melanoma tumors, with a marked EMT gene expression profile, and resultant metastases. Given the phenotypic changes associated with BAP1 levels in our mouse and human studies, we then tested the effect of modulating BAP1 on BRAF targeted therapy. Exogenous expression of BAP1 sensitized BRAF inhibitor (vemurafenib)-resistant melanoma cells, while the targeted reduction of BAP1 desensitized BRAF inhibitor-sensitive melanoma cells. BRAF mutant/BAP1 loss mice failed to exhibit a marked response to vemurafenib treatment compared to control mice. These data implicate regulation of BAP1 to be a major mechanism that characterizes a highly malignant and treatment-resistant subset of tumors. Our study indicates that nongenomic reduction in BAP1 through ZEB1 transcriptional modulation may be a key factor in aggressive CM.

This abstract is also being presented as Poster A30.

Citation Format: Haifeng Zhu, Junna Oba, Xiaoxing Yu, Caitlin A. Creasy, Marie-Andrée Forget, Fernando Carapeto, Cara L. Haymaker, Chang-Jiun Wu, Tatiana V. Karpinets, Wei-Lien Wang, Michael T. Tetzlaff, Alexander J. Lazar, Gordon B. Mills, Amanda R. Moore, Yu Chen, Jianhua Zhang, Jeffrey E. Gershenwald, Jennifer A. Wargo, Chantale Bernatchez, Patrick Hwu, P. Andrew Futreal, Scott E. Woodman. Nongenomic BAP1 aberrancy drives highly aggressive cutaneous melanoma phenotype [abstract]. In: Proceedings of the AACR Special Conference on Melanoma: From Biology to Target; 2019 Jan 15-18; Houston, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(19 Suppl):Abstract nr PR03.

Peripheral cytokines are not influenced by the type of surgical approach for non-small cell lung cancer by four weeks postoperatively

OBJECTIVES

The influence of surgical approach on systemic inflammatory response and the subsequent oncologic impact for non-small cell lung cancer is debated. We aimed to measure the effects of thoracic surgical approach on peripheral cytokine milieu over time.

METHODS

Patients undergoing primary lung resection without neoadjuvant therapy (2016-2018) were evaluated. A panel of 43 cytokines, angiogenic factors, and inflammatory molecules (CAFs) were evaluated in peripheral blood preoperatively, at 24 -hs and 4-weeks postoperatively. Differences between CAFs in patients undergoing thoracotomy versus video-assisted thoracoscopic surgery (VATS) at all timepoints were assessed using Student's t-test.

RESULTS

76 patients with available peripheral CAF panels met inclusion criteria. Thoracotomy was performed in 53 (70 %) patients while VATS was undertaken in 23 (30 %). Upon examination of known inflammatory CAFs, including IL-1β, IL-6, IL-8, IL-10, IFN-γ, and soluble (s) CD27, no differences were detected at 24 h or 4 weeks postoperatively between surgical groups. Examination of trends over time did not demonstrate any temporal derangements for these CAFs, with return to baseline levels by 4 weeks postoperatively for both groups. Evaluation of soluble (s) checkpoint molecules, including sPD-1, sPD-L1, sTIM-3, and sCTLA-4, did not reveal any differences in the immediate postoperative or long-term recovery period.

CONCLUSIONS

Peripheral immune profiles following pulmonary resection do not appear to differ between VATS and thoracotomy postoperatively. CAF fluctuations are transient and recover rapidly. These results, at the peripheral cytokine level, suggest that the surgical approach for lung cancer is unlikely to alter the effectiveness of novel immune-modulating systemic therapies, although more studies are needed to validate these findings.

Abstract D075: Investigating the immuno-biology underlying differential response to immunotherapy in White and non-White patients with metastatic acral melanoma

Background: Acral melanoma (ACML), the rarest form of melanoma (MEL) represents 4-6% of all MEL cases however it is the most common subtype darker pigmented individuals accounting for up to 70% of all cases. Checkpoint inhibitors (CPI) have emerged as an efficacious treatment option. In cutaneous melanoma (CtMEL), tumor mutational burden (TMB) correlates with response rate. Despite low TMB in AMEL, responses to CPI parallel those in CtMEL. Given the differences in ethnicity among ACML patients compared CtMEL patients we aimed to study: (i) the correlation between response and TMB, (ii) the relationship between ethnicity and response and (iii) the underlying immune-biology accounting for differential responses. Method: All advanced and metastatic ACML patients (pts) treated with anti-CTLA4 (ipilimumab) or anti-PD1 (pembrolizumab or nivolumab) immunotherapy between March 2011 and January 2019 at MD Anderson Cancer Center, Texas, were included in this retrospective analysis. Clinical response, progression free survival and overall survival (PFS and OS) and their correlation to ethnicity and TMB were evaluated. Objective response was measured using RECIST 1.1 and analyzed using logistic regression. PFS and OS were assessed using the Kaplan Meir method and log-rank test. TMB was predicted using validated algorithm based on a defined gene mutation set obtained using next generation sequencing. Results: 44 pts with Stages III-IV ACML (IIIA: 2%, IIIB 9%, IIIC 27%, IV-M1A: 16%, IV-M1B: 25%, IV-M1C: 20%, IV-M1D2%) were included in the analysis. Median age was 63 years old (39-88) and 60% were men. Of 44 patients 12 (27%) self-identified as Hispanic, 2 as (5%) Asian and 30 (68%) as White. The overall response rate was nearly 5 times times higher in Hispanic compared to White pts (OR 4.60, p-value 0.04). The median TMB in Hispanic patients was 16 mutations/mb compared to 7 mutations/mb in White pts. The median PFS and OS for White pts were 7.2 months and 34.3 months respectively while for Hispanic pts the median PFS and OS were 6.7 (log-rank p=0.69) and 26.1 months (log-rank p=0.38) respectively. In addition to this data deep immune analysis of tumor tissue including nanostring, gene expression and TCR sequencing will be assessed and reported. Conclusions: The data from this small retrospective study suggests that White pts with ACML had low response rates to CPI presumably due to low TMB while interestingly, Hispanic pts, despite relatively low TMB have high response rates paralleling those seen in the overall CtMEL population. Despite higher response rates in Hispanic patients, there was no significant difference in OS. This data together with further immune analysis provides the rationale to design prospective studies to investigate how tumor micro-environment varies with ethnicity. Additionally we will investigate the social and biological determinants that limit survival in Hispanic pts despite higher response rates.

Citation Format: Kaysia Ludford, Chantal Saberian, Sara K Nabhan, Stephen Gruschkus, Chantale Bernatchez, Natalie Jackson, Cara L Haymaker, Patrick Hwu, Adi Diab. Investigating the immuno-biology underlying differential response to immunotherapy in White and non-White patients with metastatic acral melanoma [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr D075.

CIMAC-CIDC CyTOF harmonization

e15242

Background: The Cancer Immune Monitoring and Analysis Centers – Cancer Immunology Data Commons (CIMAC-CIDC) network is a National Cancer Institute-funded initiative to identify biomarkers of mechanisms and response to cancer immunotherapy clinical trials, using state-of-the-art assay technologies. A primary platform for CIMAC-CIDC biomarker studies is CyTOF mass cytometry, which is performed at all four CIMAC laboratories. Methods: To test the ability to generate comparable data across labs, a cross-site harmonization effort was undertaken. We first harmonized SOPs between centers. Because of a new acquisition protocol introduced by the vendor (Fluidigm), we also tested this protocol across sites before finalizing the harmonized SOP. We then performed a cross-site assay harmonization experiment, using 5 shared cryopreserved PBMC samples and one lyophilized control cell preparation, along with a shared lyophilized antibody cocktail consisting of 14 markers, as validated in the HIPC consortium, plus CD45. These reagents and samples were distributed to the four sites, and FCS files were centrally analyzed by both manual gating and automated methods (Astrolabe). Results: Average CVs across sites for each cell population were reported and compared to a previous multisite CyTOF study. Once a cell recovery issue at two sites was resolved, this experiment resulted in inter-site reproducibility of under 20% CV for most cell subsets, very similar to the previous study. Conclusions: These results emphasize the ability to reproduce CyTOF across sites, and also highlights procedures, such as use of spike-in control samples, useful for tracking variability in this assay.

Single-center phase I/Ib study of concurrent intrathecal (IT) and intravenous (IV) nivolumab (N) for metastatic melanoma (MM) patients (pts) with leptomeningeal disease (LMD)

10008

Background: MM pts with LMD have a dismal prognosis, with a median overall survival (OS) < 3 months and no approved therapies. IT administration of interleukin-2 (IL2) achieves survival in ~15% of MM LMD pts, but at cost of severe toxicities. Given the favorable clinical activity and safety of systemic anti-PD1, we hypothesized that IT N administration is safe and can achieve clinical benefit in pts with LMD. Methods: The primary objectives of this first-in-human study (NCT03025256) were to determine the safety and the maximum tolerated dose (MTD) of IT N given with IV N in MM pts with LMD. Eligible pts had MM, ECOG PS < / = 2, and evidence of LMD by MRI and/or CSF cytology. Dexamethasone < / = 4mg/daily was allowed. For cycle 1, IT N is administered via intraventricular reservoir on day (D) 1; Blood and CSF is collected at multiple time points for translational research. For subsequent cycles (every 14 days), pts receive IT N on D1, followed by IV N 240 mg on D2. IT N doses evaluated were 5, 10, and 20 mg. Bayesian mTPI methodology was used to define the MTD. The study was recently amended to allow for concurrent BRAF/MEK inhibitor(i) treatment. Results: To date, 15 pts have been treated: two at 5, three at 10, and 10 at 20 mg IT N. Median age at LMD diagnosis was 41.8 (30.9-73.2) years; 6 pts are male. All pts had radiographic evidence of LMD and neurological symptoms; 8 pts had positive CSF cytology. 12 pts received prior therapies for their MM: anti-PD1 (n = 11), BRAFi/MEKi (n = 9), chemo (n = 2), IT IL2 (n = 4) other (n = 2). 11 pts had prior XRT, including whole brain RT (n = 7). 1 pt was treatment-naïve. The median numbers of IT N doses was 4 (1-42). No grade (Gr) 4-5 AEs were attributed to IT N or IV N; only 4 events (Gr 1, n = 2; Gr2, n = 2) were possibly related to the IT N. With a median follow-up of 18.7 weeks (1-83.3 wks), the median OS is 46.1 weeks (0.1-83.3). Clinical response data, translational research endpoints, including changes in CSF cytokines and cfDNA, will be reported. Conclusions: The trial demonstrates the feasibility of prospective clinical trials in MM patients with LMD. The combination of IT/ IV N was safe and well-tolerated, with no unexpected systemic or neurological toxicity. Final presentation will include results of LMD composite response assessment, comparative analysis of longitudinal CSF/blood samples to assess immunologic effects. Finally, the interim OS of the patients is encouraging, and supports further evaluation of IT administration of immunotherapy agents for pts with MM and LMD. Clinical trial information: NCT03025256.

Successful tumor-infiltrating lymphocyte (TIL) growth from uveal melanoma (UM) using a three-signal (3.0) method

3027

Background: Metastatic UM is a rare cancer with poor response rates to systemic therapy. Adoptive transfer of patient-specific TIL may represent the best strategy for treatment. TIL are harvested from primary or metastatic tumors and initially expanded in culture with high dose IL-2 prior to undergoing rapid expansion protocol and therapeutic administration. Here, we report improved rates of initial expansion using a previously described TIL 3.0 method which utilizes dual agonistic antibodies to TCR and 4-1BB (Urelumab) for stimulation, respectively, with high dose IL-2, compared to the traditional method. Methods: Between 2006 and 2019, patients were consented for TIL harvest from either primary or metastatic UM tumors. Demographics, clinical features, and outcomes of the TIL initial expansion were collected. Success rates, number of cells expanded, and days in culture for the two methods were analyzed using partially overlapping samples t-tests and z-tests. Results: There were 85 harvests and expansions from 76 patients using the traditional method and 32 expansions from 30 patients using TIL 3.0. Initial TIL expansion was successful in 97% of TIL 3.0 harvests compared to 35% for the traditional method (p < 0.001). More TIL were expanded with TIL 3.0 compared to the traditional method (291.3 million cells vs. 88.6 million cells, p < 0.001), and fewer days were required in culture (18.5 vs. 29.0, p < 0.001). Both primary UM harvests and metastatic harvests were more successful with TIL 3.0 (90% vs. 12% for primary, p < 0.001, and 100% vs. 42% for metastatic, p < 0.001). Conclusions: Expansion of UM tumors via the TIL 3.0 method led to successful growth in 97% of harvests. Therapeutic administration to patients with TIL 3.0 is under active investigation. [Table: see text]

Abstract 4062: Activation of innate and adaptive immunity using intratumoral tilsotolimod (IMO-2125) as monotherapy in patients with refractory solid tumors: a phase Ib study (ILLUMINATE-101)

While checkpoint inhibitor therapy has transformed treatment of multiple tumor types, many patients remain refractory. Tilsotolimod, a toll-like receptor 9 agonist, has been shown in preclinical models to activate plasmacytoid dendritic cells and increase T cell infiltration to the tumor microenvironment. Preliminary results of a phase 1/2 study suggested that intratumoral injection of tilsotolimod in combination with ipilimumab may revive an immune response in patients with immune checkpoint inhibitor-resistant metastatic melanoma. To further explore the role of tilsotolimod in modulating the tumor immune microenvironment, we conducted a Phase Ib monotherapy trial (ILLUMINATE-101). Adults with histologically or cytologically confirmed diagnosis of cancer not amenable to curative therapies received intratumoral tilsotolimod in doses escalating from 8 mg to 32 mg into a single lesion at weeks 1, 2, 3, 5, 8, and 11. Objectives of the dose evaluation portion included characterizing safety and pharmacokinetics, and evaluating alterations in the tumor microenvironment. Blood samples and tumor biopsies of injected and distal lesions were obtained at baseline and on treatment. Immune analyses included evaluation using Nanostring and/or flow cytometry of activation of the type 1 interferon (IFN) pathway, IFN gamma levels, activation of dendritic cell subsets, and changes in T cell status. As of November 7, 2018, 41 patients have been enrolled, including 38 patients into the dose evaluation portion and 3 patients into a melanoma expansion cohort. No dose-limiting toxicities or treatment-related adverse events have been observed. Within 24 hours, fresh tumor biopsies showed significant increases in IFN gamma levels, activation of the type 1 IFN pathway, induction of an antigen processing gene signature (a measure of the MHC class I antigen presentation pathway), and maturation of dendritic cells as measured by expression of HLA-DR (MHC class II), compared to pretreatment biopsies. Of 25 evaluable patients who received at least 1 dose of tilsotolimod and had at least 1 post-baseline disease assessment, 12 (48%) had a RECIST v1.1 disease assessment of stable disease. For patients with at least one disease assessment following documentation of stable disease (n=8), duration of stable disease ranged from 0.53 to 4.2+ months, with 3 patients ongoing. These results demonstrate that single agent tilsotolimod was well tolerated and induced robust alterations in the tumor microenvironment.

Citation Format: Hani M. Babiker, Vivek Subbiah, Orla Maguire, Shah Rahimian, Hans Minderman, Cara L. Haymaker, Chantale Bernatchez, Erkut Borazanci, James Geib, Srinivas K. Chunduru, Peter M. Anderson, Igor Puzanov, Adi Diab. Activation of innate and adaptive immunity using intratumoral tilsotolimod (IMO-2125) as monotherapy in patients with refractory solid tumors: a phase Ib study (ILLUMINATE-101) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4062.

Association of relative neutrophilia with a distinct immunoinhibitory milieu in non-small cell lung cancer

e14047

Background: Elevated neutrophil-to-lymphocyte ratio (NLR) has been associated with poor prognosis in non-small cell lung cancer (NSCLC); the biological underpinnings of this observation have not been fully elucidated. We examined the relationships between peripheral neutrophil counts (PMN), NLR, circulating cytokines and angiogenic factors (CAF), and tumor microenvironment (TME) features in NSCLC. Methods: 150 patients with resectable NSCLC were enrolled in an immunoprofiling project. A panel of 43 CAFs was used to analyze preoperative plasma samples. Chemotherapy-naïve patients with CAF and a complete blood count ≤30 days preoperatively were included (n = 66; Table). For a subset, transcriptional signatures (MCP-counter, n = 50) and flow cytometry (n = 19) were used to identify TME phenotypes. Results: Increased PMNs were associated with increased pro-inflammatory CAF such as IL-1b (r = 0.392) and IL-6 (r = 0.339), as well as Th17/Tc17 associated CAF IL-17A (r = 0.320) and TNF-a (r = 0.368). Elevated NLR was inversely correlated with the lymphocyte activation marker soluble CD27 (r = -0.320, p = 0.009). This negative association was mirrored in the TME, as tumor neutrophil signatures were inversely correlated with a local IFN-g gene signature (r = -0.626, p < 0.001). Interestingly, a Th17/Tc17 peripheral signature (elevated IL-17A) was associated with an enrichment of CD8+TIM3+ cells (r = 0.623, p = 0.042) in the tumor. While this requires confirmation in a larger cohort, this correlation provides a potential rationale for targeting TIM3 in this population. Upon analysis of clinical characteristics, peripheral PMNs and NLR were higher among patients with squamous histology (PMN p = 0.009; NLR p = 0.034) and positively correlated with tumor size (PMN r = 0.344, p = 0.004; NLR r = 0.363, p = 0.003). Conclusions: A relative neutrophilia in NSCLC patients is associated with an inflammatory milieu suggestive of a Th17/Tc17 presence and decreased lymphocyte activation that is reflected within the TME. Further investigation is needed to define the role of NLR as a predictive biomarker and to identify whether neutrophils or Th17/Tc17 T cells could serve as a therapeutic target to improve immunotherapy response in NSCLC.[Table: see text]

Phase II trial of nab-paclitaxel (ABI) and ipilimumab (ipi) in patients with treatment naïve metastatic melanoma

9554

Background: Conventional chemotherapies possess intrinsic immune-regulatory properties. Some taxanes for instance, stimulate antigen presentation and impair regulatory T-cells while leaving effector T cells intact. Combining chemotherapies with immune checkpoint inhibitor at carefully designed dosing regimens may increase tumor cell susceptibility to immune-mediated death and thus enhance therapeutic efficacy. We describe the safety and updated efficacy of ABI and ipi in patients with metastatic melanoma. Methods: In this open-label, single center, phase II trial, ABI was administered to treatment naïve metastatic patients at 150mg/m2 on days 1,8 and 15 every 4 weeks and ipi at 3mg/kg on day 1 every 3 weeks limited to 4 cycles until disease progression or unacceptable toxicity. Endpoints included ORR, OS and safety. Results: 18 of 21 enrollees between 6/2013 and 6/2015 with Stage IV melanoma (M1c: 56%, M1b: 33%, M1a: 11%) were included in the analysis. The median age was 57 years old (33-69) and 67% were men. 44% harbored BRAF mutations. Median duration of treatment was 9 weeks (5 to 17). Median follow-up time for OS analysis was 22.5 months (2 to 52 months). 12 and 24 month OS were 77.8% and 60.6% respectively with median not yet reached. The ORR by by irRECIST was 27.8%. Grade 3 adverse events were reported in 50% of patients, the most common being neutropenia. 17% of patients had grade 3 immune-related adverse events, the most common being hypophysitis and colitis. Immune analysis showed absolute lymphocyte count was significantly elevated post treatment compared with pre-treatment (p = 0.024). In addition, deep immune analysis of peripheral blood samples and tumor tissue including nanostring, gene expression and TCR sequencing will be assessed and reported. Conclusions: The combination of ipi and ABI in this small study demonstrates acceptable safety, tolerability and clinical activity. ABI may contribute to tumor cytoreduction and enhance antitumor clinical response of ipi without impactful immunosuppression. This data together with further immune analysis may provide rationale to design prospective chemo-immunotherapy regimens and treatments for metastatic melanoma and other solid tumors. Clinical trial information: NCT01827111.

Lymphodepletion (LD), tumor-infiltrating lymphocytes (TIL) and high (HD-IL2) versus low-dose (LD-IL2) IL-2 followed by pembrolizumab (pembro) in patients (pts) with metastatic melanoma (MM)

9543

Background: TIL adoptive cell transfer (ACT) therapy can produce durable responses for MM pts although efficacy appears lower in the era of checkpoint inhibitors. Toxicities from HD-IL2, including sepsis physiology, limits widespread use of this regimen. Suppression of transferred TIL by either tumor cells or the tumor microenvironment could limit TIL responses. Pembro is known to promote T cell activation, thus, we evaluated the efficacy and safety of TIL with pembro with HD-IL2 versus LD-IL2. Methods: Pts with MM who had tumor harvested and cryopreserved TIL at MD Anderson with PS 0-1 and normal organ function were eligible. All pts received a standard LD regimen consisting of cyclophosphamide and fludarabine, followed by infusion of pooled ex-vivo expanded TIL and either HD-IL2 (Arm 1: 720,000 IU/kg IV q 8 hrs up to 15 doses) or LD-IL2 (Arm 2: 2 million IU SC for 14 d). Pts received pembro 200mg IV starting 21 d post T cell infusion every 3 wks for up to 2 yrs. Pts were randomized 1:1 based on stage and LDH. Paired blood and tumor biopsies were obtained prior to LD, prior to first and second dose of pembro and at time of progression. Results: A total of 36 pts were planned to enroll (18 in each arm); however, the protocol met pre-specified futility boundaries in Arm 1 which prompted early closure after treatment of 14 pts (7 in each Arm). Median age was 50 yrs, 6 were female, 8 had cutaneous melanoma, 2 mucosal, 2 uveal and 2 unknown primary. 86% were stage M1c, 14% M1D, 50% had LDH elevation. Median lines of prior therapy were 3 (range 1-6), including prior anti PD-1 in 13 pts. Best overall response was 1 PR (for 10 mos), 2 SD, 3 PD, 1 NE in Arm 1; 1 PR (ongoing over 36 mos), 1 SD, 5 PD in Arm 2. With median follow up of 9.2 mos, PFS was 3.9 mos for Arm 1 and 2.1 mos for Arm 2 (p = 0.99). Median OS was 9.7 mos for Arm 1 and 8.8 mos for Arm 2 (p = 0.71). Toxicity was similar in both Arms but with lower rates of grade 3 febrile neutropenia (57% vs. 71%) and shorter hospital stay (median 16 vs. 18 d) in Arm 2 vs. Arm 1. Conclusions: In a heavily treated pt population, TIL with pembro achieved low response rates. Use of LD-IL2 did not diminish efficacy and may be better tolerated than HD-IL2 for TIL ACT. Correlative studies are ongoing to determine mechanisms of treatment response and failure. Clinical trial information: NCT02500576.

T cell repertoire analysis of non-small cell lung cancer patients treated with neoadjuvant nivolumab alone or in combination with ipilimumab (NEOSTAR trial)

8532

Background: Neoadjuvant immune checkpoint inhibitors (ICIs) are being explored in resectable non-small cell lung cancer (NSCLC). Here, we studied the composition and changes in the T cell repertoire in a cohort of NSCLC patients (n = 44) treated with neoadjuvant nivolumab (N) alone or in combination with ipilimumab (NI) followed by surgery (NEOSTAR trial). Methods: Sequencing of the variable CDR3β chain of the T cell receptor (TCR) involved in antigen binding was performed in pre-treatment and surgical tumors, matched adjacent uninvolved lung specimens, as well as paired longitudinal blood at baseline, prior to each dose of therapy, prior to surgery, and within 8 weeks post-surgery. T cell repertoire density, diversity, and clonality (reactivity) were evaluated in addition to tumor PD-L1 expression pre- and post-neoadjuvant treatment. Results: Median T cell diversity in the blood post-therapy was 3.3-fold higher in NI- compared to N-treated patients (40,993 [NI, n = 3] vs 12,177 [N, n = 4] unique TCR rearrangements, n.s.). However, median T cell clonality in the blood was 3.5-fold higher in N- than NI-treated patients post-therapy (0.093 [N, n = 4] vs 0.026 [NI, n = 3], n.s.). Median clonality was 3.8-fold higher in the tumor post-therapy in patients receiving NI than in those receiving N (0.076 [NI, n = 7] vs 0.020 [N, n = 5], n.s.). Interestingly, diversity in the blood at baseline and in the tumor post-therapy were positively correlated ([n = 7], r = 0.82; p = 0.023), which may reflect an influx of cells from the periphery following ICIs. Importantly, higher baseline T cell clonality in the blood was associated with a lower % of viable tumor at time of surgery in both treatment arms ([n = 7], r = -0.77; p = 0.04). Conclusions: Our study is the first to assess the TCR repertoire in NSCLC patients treated with combination neoadjuvant NI and highlights potential mechanistic differences compared to N alone. Neoadjuvant NI is associated with higher clonality in tumors and lower clonality in blood post-therapy, suggesting increased T cell trafficking into the tumor. Finally, lower pre-treatment clonality in the periphery was correlated with higher % viable tumor post-neoadjuvant ICIs. Clinical trial information: NCT03158129.

Adoptive transfer of tumor-infiltrating lymphocytes in patients with sarcomas, ovarian, and pancreatic cancers

TPS2650

Background: Adoptive cell therapy (ACT) with tumor-infiltrating lymphocytes (TIL) has a long history of efficacy in metastatic melanoma, and is being increasingly considered across other solid tumors. Preclinical data generated at MD Anderson Cancer Center has demonstrated the ability to grow TIL from a variety of tumor types including various types of sarcomas, ovarian and pancreas cancers. We are testing the efficacy of TIL across multiple tumor types using two different manufacturing protocols. Methods: We are conducting two ongoing investigator initiated basket TIL therapy trials. The first (NCT03449108) includes cohorts with poorly differentiated soft tissue and bone sarcomas, osteosarcoma, and platinum resistant ovarian cancer. The TIL product used in this trial is an investigational cell product (LN-145, Iovance Biotherapeutics, Inc.). The second trial (NCT03610490) includes cohorts of osteosarcoma, platinum resistant ovarian cancer, and pancreatic cancer (who have progressed on, or received maximal benefit from, front-line therapy). For this trial, TIL are manufactured at MD Anderson Cancer Center using a protocol that includes the use of urelumab (an agonistic anti-CD137 antibody) combined with T cell receptor activation during TIL expansion. In both trials eligible subjects undergo tumor harvest using a surgical excisional biopsy of the tumor for TIL manufacturing, receive a modified cyclophosphamide and fludarabaine lymphodepletion regimen and up to six doses of IL-2 (600,000 IU/kg) following TIL infusion. No intervening therapy is allowed between tumor harvest and initiation of lymphodepletion. The primary endpoint for each cohort is ORR as assessed by investigators using RECIST 1.1 criteria. The Simon’s two stage design is used to monitor the efficacy of each cohort independently. In the first stage, 10 patients will be treated per cohort. If there is no confirmed response in these 10 evaluable patients, the cohort will be terminated. If the cohort moves forward to Stage II, an additional 8 patients will be treated leading to a total of 18 patients. Three or more responders out of 18 treated patients for the cohort will be considered clinically relevant to justify further investigation. Enrollment is ongoing in all cohorts in both trials. An accrual update will be provided at the annual meeting. Clinical trial information: NCT03449108, NCT03610490.

Interleukin-6 is potential target to de-couple checkpoint inhibitor-induced colitis from antitumor immunity

2616

Background: A deep understanding of the immunobiology of checkpoint inhibitor (CPI) induced immune related toxicities, such as immune related enterocolitis (irEC), and how these compare to the immune signatures in tumors could lead to the development of strategies that de-couple autoimmunity from anti-tumor immunity. Methods: Total RNA from patient-matched irEC and normal colon FFPE tissue from patients [n = 12] receiving CPIs were profiled with the 770 gene NanoString nCounter PanCancer Immune Profiling Panel (NanoPCIP). The mean fold change in gene expression from normal vs. irEC inflamed colonic tissue and baseline vs. on-treatment tumor samples from patients responding or non-responding to ipilimumab based therapy were analyzed. C57BL/6 mice with B16.BL6 melanoma tumors were treated with systemic anti-IL-6 + anti-CTLA-4 vs. anti-CTLA4 alone vs. placebo and tumor size was measured. Results: In patients with irEC, the highest significantly upregulated differentially expressed gene (DEG) in inflamed colon tissue encoded for IL-6 (Fold change +24.1). None of the significant and highest upregulated DEGs in the colitis, including IL-6, were significantly upregulated in responding tumors. Interestingly, IL-6 was also the highest upregulated DEG in non-responding tumors numerically. When comparing mean fold changes across these analyses, the gene with the largest difference in upregulatation between colitis and responding tumors was IL-6; the other highest upregulated genes in colitis encoded for neutrophil and monocyte chemotactic molecules. In our mouse models, the addition of IL-6 blockade to anti-CTLA-4 therapy significantly improved tumor shrinkage compared to anti-CTLA-4 alone. Conclusions: Our data demonstrates that IL-6-mediated inflammation may be more prevalent in irEC and tumors not responding to CPIs than in tumors responding, and blocking IL-6 enhances CPI anti-melanoma activity. Targeting IL-6 may ameliorate irEC without hindering anti-tumor immunity.

Phase Ib clinical investigation of intraperitoneal ipilimumab and nivolumab in patients with peritoneal carcinomatosis due to gynecologic malignancy

TPS5606

Background: The peritoneal cavity is a frequent site of metastasis and recurrence for gynecologic malignancy, including approximately 80% of epithelial ovarian cancer (EOC) that presents with peritoneal involvement. These observations have led to the use of intraperitoneal (IP) route of administration for traditional cytotoxic chemotherapy. IP immunotherapy is a recognized but under explored area of clinical investigation with many potential advantages. Indeed, IP administered antibodies in both animals and human subjects are associated with absent or much lower peripheral blood concentrations. In addition to higher local and lower systemic exposure, other theoretical advantages include preferential binding to intraperitoneal and intratumoral immune cells, and absorption through the draining lymphatics of the peritoneal cavity. These pelvic and peri-aortic lymph nodes represent the most relevant lymphoid organs and as such may be the ideal site for T cell activation and trafficking back to the peritoneal tumor. Methods: The trial (NCT03508570) is a single-institution phase Ib trial to determine the recommended phase II dosing (RP2D) of IP administration of nivolumab in combination with ipilimumab. For the purpose of dose finding, the assessment period for dose limiting toxicity (DLT) is 12 weeks. The trial starts with a safety lead-in to confirm the safety of IP nivolumab before combining it with ipilimumab. A maximum sample size of 12 will be used to find the RP2D for nivolumab, up to 24 patients for the combination, and a planned expansion will be carried out such that at least 12 EOC patients are treated at RP2D of the intraperitoneal combination strategy. The secondary objectives are to describe the pharmacokinetics and toxicities, and to estimate the clinical benefit rate for the expansion cohort. Translational objectives include description of immunologic and biologic changes in serial blood and IP fluid collections as well as pre and on-treatment biopsies. Eligibility criteria include recurrent or progressive biopsy-confirmed platinum resistant EOC or other gynecologic cancer with measurable peritoneal disease, and no exposure to prior treatment with checkpoint inhibition. Enrollment began in January of 2019 with 3 subjects enrolled to date. Accrual update will be provided at the annual meeting. Clinical trial information: NCT03508570.

A preclinical study of tumor-infiltrating lymphocytes in NSCLC

161

Background: Multiple clinical studies have shown that adoptive cell transfer (ACT) of autologous tumor-infiltrating lymphocytes (TIL) is remarkably effective in melanoma patients. Non-small cell lung cancer (NSCLC) shares similarities with melanoma in terms of mutational burden and sensitivity to immune checkpoint inhibitors. We therefore sought to test whether TIL ACT may represent a viable option for the treatment of NSCLC patients. We utilized tissue collected from patients enrolled on the prospective ImmunogenomiC prOfiling of Non-small cell lung cancer (ICON) study. Methods: TIL and tissue-infiltrating lymphocytes were expanded ex vivo from 97 freshly resected early-stage localized NSCLC tumors and 39 matched uninvolved lung tissues. Growth and functional characteristics of TIL were assessed via flow cytometry, TIL-tumor reactivity assays, and analysis of TCRβ sequencing data. Results: NSCLC showed an increased proportion of CD3+ lymphocytes within the tumor-infiltrating leukocyte component as compared to matched normal lung tissue. The TIL compartment included a suppressed CD8+ T cell subset expressing significantly higher levels of PD-1 and lacking cytolytic potential compared to T cells expanded from normal tissue. TIL contained a higher proportion of proliferating (Ki67+) CD8+CD103+ tissue-resident memory (TRM) cells expressing activation markers such as CTLA4, LAG3, PD1 and ICOS, and increased CD4+ Tregs. Despite a highly immunosuppressive environment, TIL expansion was achieved with a success rate of 68% (n = 97) but appeared hindered in patients undergoing neoadjuvant chemotherapy treatment prior to surgery (56.2%, n = 16 vs 72.5% success rate in therapy-naïve patients). In addition, expansion efficiency (number expanded and time of culture) of TIL and matched lung residing lymphocytes were significantly associated (r = 0.379, p = 0.017, n = 39). Importantly, expanded CD8+ TIL products were oligoclonal and showed reactivity toward autologous tumors. Conclusions: Although NSCLC TIL are functionally inhibited in vivo they can be successfully expanded ex vivo and demonstrate recognition of autologous tumor cells. These data suggest that TIL can potentially be used for adoptive T cell-based immunotherapy in NSCLC.

Preclinical development of tumor-infiltrating lymphocyte therapy for metastatic colorectal cancer

95

Background: Immunotherapy has become an effective cancer therapy, particularly in the case of checkpoint blockade and adoptive T-cell therapy (ACT). ACT exploits the presence of tumor-infiltrating lymphocytes (TIL) by exponentially expanding their numbers ex vivo and re-infusing them into the patient in an autologous setting. With the effectiveness of TIL therapy already well established in multiple phase II studies in melanoma, there is a push to translate it to other cancers in need of improved therapies. Colorectal cancer (CRC) is a cancer where the presence of TIL has been strongly correlated with increased survival. Metastatic CRC (mCRC) has a poor outcome with median overall survival of less than 3 years. At present anti-PD1 therapy is only active in the small subset of mCRC patients (4%) that are MSI-high. We sought to evaluate the ability to generate and characterize TIL from patients with mCRC to provide a rationale for future TIL therapy in this disease. Methods: To assess the feasibility of utilizing TIL ACT for this patient population, we characterized the immune infiltrate of mCRC, TIL growth from tumor fragments (n = 24), as well as the TIL repertoire (n = 4) and anti-tumor potential in samples with available autologous tumor target. Results: Flow cytometry analysis detected a CD4-rich T-cell infiltration at the tumor site as well as a scarce yet activated CD8+ TIL population. The outgrowth of CD8+ TIL from tumor fragments in media containing IL-2 was potentiated by the addition of an agonistic 4-1BB antibody (Urelumab, BMS). Additionally, the use of a 4-1BB mAb improved the likelihood of growing TIL (63% [14/24] to 83% [20/24]) and increased the total yield of TIL grown. T-cell receptor sequencing showed enrichment in the tumor of CD8+ T-cell clones shared between the blood and tumor, suggesting selective expansion at the tumor site. Using IFNγ ELISPOT, CD8+ TIL from one patient with an MSS tumor were found to be reactive against a peptide derived from mutated TP53R116W restricted to HLA-B*39:01. Conclusions: It is possible to expand CD8+ T cells from microsatellite stable (MSS) mCRC that are able to target tumor antigens. Although preliminary, the initial data suggest the feasibility of TIL therapy for mCRC.