Faculty Bibliography

Background Efficient ex-vivo generation of functional tumor-specific T cells with memory phenotype remains a significant hurdle for the broad application of adoptive cell transfer (ACT) protocols for the treatment of cancer. Genetically engineered T cells represent one option, but genetic manipulation of T cells presents significant challenges in terms of complexity and generation time. Here, we describe a novel nanoparticle-based approach for generating tumor- specific T cells at clinical grade and scale from the endogenous T cell repertoire using artificial antigen presenting cells (aAPC). Methods Our aAPC consist of a paramagnetic nanoparticle to which humanized HLA-A2-Ig dimer-molecules and anti-CD28 antibodies are covalently linked. aAPC are loaded with multiple HLA-A2 restricted peptides and used to magnetically enrich and expand tumor-specific CD8+ T cells. Using peptide loaded aAPC, a fully enclosed, semi- automated, GMP T cell expansion platform has been developed that consistently generates clinically relevant numbers of tumor-specific, central and effector memory CD8+ T cells in 14 days, providing an alternative to genetic manipulation of T cells. Results Starting from a healthy donor leukopak, CD8+ T cells were generated using an aAPC cocktail loaded with 5 HLA-A2 epitopes from AML tumor antigens WT1, PRAME and cyclin A1. On average (n>20), 1-2 x109 T cells were generated that were 90% memory T cells with about 50% central memory and 40% effector memory CD8+ T cells. AML-specific T cells were expanded 500 to >5000-fold from low frequency precursor populations. These T cells were fully functional, as demonstrated by intra-cellular cytokine analysis and tumor cell killing. The system was also used to generate Mart-1 specific T cells of the same quality from cryopreserved PBL from melanoma patients. Additional data analyzing the TCR repertoire of the expanded AML and melanoma-specific T cells will be presented. Conclusions AIM ACT is a novel nanoparticle-based T cell expansion platform for the rapid, streamlined generation of clinically-relevant numbers of tumor-specific, central and effector memory CD8+ T cells from donor and patient PBMC in 14 days. The results reported here describe a platform that will be used in a multi-institution phase I clinical trial of adoptive T cell transfer for the treatment of AML patients pre- and post-allogeneic hematopoietic stem cell transplant. The flexibility of the AIM ACT system, as demonstrated using both AML and melanoma antigens, shows the potential for clinical application in other heme and solid tumors. Additionally, the system can be used for targeting both known and neo-epitopes

PURPOSE/OBJECTIVE:To assess the association of baseline tumor size (BTS) with other baseline clinical factors and outcomes in pembrolizumab-treated patients with advanced melanoma in KEYNOTE-001 (NCT01295827). EXPERIMENTAL DESIGN/METHODS:BTS was quantified by adding the sum of the longest dimensions of all measurable baseline target lesions. BTS as a dichotomous and continuous variable was evaluated with other baseline factors using logistic regression for objective response rate (ORR) and Cox regression for overall survival (OS). Nominal P values with no multiplicity adjustment describe the strength of observed associations. RESULTS:Per central review by RECIST v1.1, 583 of 655 patients had baseline measurable disease and were included in this post hoc analysis. Median BTS was 10.2 cm (range, 1-89.5). Larger median BTS was associated with Eastern Cooperative Oncology Group performance status 1, elevated lactate dehydrogenase (LDH), stage M1c disease, and liver metastases (with or without any other sites) (all P ≤ 0.001). In univariate analyses, BTS below the median was associated with higher ORR (44% vs 23%; P < 0.001) and improved OS (hazard ratio, 0.38; P < 0.001). In multivariate analyses, BTS below the median remained an independent prognostic marker of OS (P < 0.001) but not ORR. In 459 patients with available tumor programmed death ligand 1 (PD-L1) expression, BTS below the median and PD-L1-positive tumors were independently associated with higher ORR and longer OS. CONCLUSIONS:BTS is associated with many other baseline clinical factors but is also independently prognostic of survival in pembrolizumab-treated patients with advanced melanoma.

Immune-checkpoint blockade (ICB), in particular PD-1 inhibition, has rapidly changed the treatment landscape and altered therapeutic paradigms across many tumor types, with unprecedented rates of durable clinical responses in a number of cancers. Despite this success, only a subset of patients responds to ICB and, as a result, predictive biomarkers would be useful to guide the selection of patients for these therapies. This article highlights currently used biomarkers, as well as several promising novel candidates, and also discusses the challenges involved in establishing their analytic validity and clinical utility. Progress is being evaluated in melanoma and non-small cell lung cancer, for which PD-1 ± CTLA-4 inhibitors have become standard therapy, to other malignancies for which PD-L1 inhibitors remain investigational. Although single biomarkers have substantial limitations, a combination of biomarkers that reflect the interaction of host and tumor will likely be needed to provide a reproducible surrogate for the benefit of checkpoint modulation. Cancer Immunol Res; 6(10); 1122-8. ©2018 AACR.

Combination anti-cytotoxic T lymphocyte antigen 4 (CTLA-4) and anti-programmed cell death protein 1 (PD-1) therapy promotes antitumor immunity and provides superior benefit to patients with advanced-stage melanoma compared with either therapy alone. T cell immunity requires recognition of antigens in the context of major histocompatibility complex (MHC) class I and class II proteins by CD8⁺ and CD4⁺ T cells, respectively. We examined MHC class I and class II protein expression on tumor cells from previously untreated melanoma patients and correlated the results with transcriptional and genomic analyses and with clinical response to anti-CTLA-4, anti-PD-1, or combination therapy. Most (>50% of cells) or complete loss of melanoma MHC class I membrane expression was observed in 78 of 181 cases (43%), was associated with transcriptional repression of HLA-A, HLA-B, HLA-C, and B2M, and predicted primary resistance to anti-CTLA-4, but not anti-PD-1, therapy. Melanoma MHC class II membrane expression on >1% cells was observed in 55 of 181 cases (30%), was associated with interferon-γ (IFN-γ) and IFN-γ-mediated gene signatures, and predicted response to anti-PD-1, but not anti-CTLA-4, therapy. We conclude that primary response to anti-CTLA-4 requires robust melanoma MHC class I expression. In contrast, primary response to anti-PD-1 is associated with preexisting IFN-γ-mediated immune activation that includes tumor-specific MHC class II expression and components of innate immunity when MHC class I is compromised. The benefits of combined checkpoint blockade may be attributable, in part, to distinct requirements for melanoma-specific antigen presentation to initiate antitumor immunity.

Purpose To increase awareness, outline strategies, and offer guidance on the recommended management of immune-related adverse events in patients treated with immune checkpoint inhibitor (ICPi) therapy. Methods A multidisciplinary, multi-organizational panel of experts in medical oncology, dermatology, gastroenterology, rheumatology, pulmonology, endocrinology, urology, neurology, hematology, emergency medicine, nursing, trialist, and advocacy was convened to develop the clinical practice guideline. Guideline development involved a systematic review of the literature and an informal consensus process. The systematic review focused on guidelines, systematic reviews and meta-analyses, randomized controlled trials, and case series published from 2000 through 2017. Results The systematic review identified 204 eligible publications. Much of the evidence consisted of systematic reviews of observational data, consensus guidelines, case series, and case reports. Due to the paucity of high-quality evidence on management of immune-related adverse events, recommendations are based on expert consensus. Recommendations Recommendations for specific organ system-based toxicity diagnosis and management are presented. While management varies according to organ system affected, in general, ICPi therapy should be continued with close monitoring for grade 1 toxicities, with the exception of some neurologic, hematologic, and cardiac toxicities. ICPi therapy may be suspended for most grade 2 toxicities, with consideration of resuming when symptoms revert to grade 1 or less. Corticosteroids may be administered. Grade 3 toxicities generally warrant suspension of ICPis and the initiation of high-dose corticosteroids (prednisone 1 to 2 mg/kg/d or methylprednisolone 1 to 2 mg/kg/d). Corticosteroids should be tapered over the course of at least 4 to 6 weeks. Some refractory cases may require infliximab or other immunosuppressive therapy. In general, permanent discontinuation of ICPis is recommended with grade 4 toxicities, with the exception of endocrinopathies that have been controlled by hormone replacement. Additional information is available at www.asco.org/supportive-care-guidelines and www.asco.org/guidelineswiki .

Purpose Pembrolizumab provides durable antitumor activity in metastatic melanoma, including complete response (CR) in about 15% of patients. Data are limited on potential predictors of CR and patient disposition after pembrolizumab discontinuation after CR. We describe baseline characteristics and long-term follow-up in patients who experienced CR with pembrolizumab in the KEYNOTE-001 study ( ClinicalTrials.gov identifier: NCT01295827). Patients and Methods Patients with ipilimumab-naive or -treated advanced/metastatic melanoma received one of three dose regimens of pembrolizumab. Eligible patients who received pembrolizumab for ≥ 6 months and at least two treatments beyond confirmed CR could discontinue therapy. Response was assessed every 12 weeks by central Response Evaluation Criteria in Solid Tumors version 1.1. For this analysis, CR was defined per investigator assessment, immune-related response criteria, and potential predictors of CR were evaluated using univariate and multivariate analyses. Results Of 655 treated patients, 105 (16.0%) achieved CR after median follow-up of 43 months. At data cutoff, 92 patients (87.6%) had CR, with median follow-up of 30 months from first CR. Fourteen (13.3%) patients continued to receive treatment for a median of ≥ 40 months. Pembrolizumab was discontinued by 91 patients (86.7%), including 67 (63.8%) who proceeded to observation without additional anticancer therapy. The 24-month disease-free survival rate from time of CR was 90.9% in all 105 patients with CR and 89.9% in the 67 patients who discontinued pembrolizumab after CR for observation. Tumor size and programmed death-ligand 1 status were among the baseline factors independently associated with CR by univariate analysis. Conclusion Patients with metastatic melanoma can have durable complete remission after discontinuation of pembrolizumab, and the low incidence of relapse after median follow-up of approximately 2 years from discontinuation provides hope for a cure for some patients. The mechanisms underlying durable CR require further investigation.

Immune checkpoint inhibitors targeting programmed cell death 1 (PD-1) or its ligand (PD-L1) have been shown to be effective in treating patients with a variety of cancers. Biomarker studies have found positive associations between clinical response rates and PD-L1 expression on tumor cells, as well as the presence of tumor infiltrating lymphocytes (TILs). It is currently unknown whether tumors associated with neurofibromatosis types 1 and 2 (NF1 and NF2) express PD-L1. We performed immunohistochemistry for PD-L1 (clones SP142 and E1L3N), CD3, CD20, CD8, and CD68 in NF1-related tumors (ten dermal and six plexiform neurofibromas) and NF2-related tumors (ten meningiomas and ten schwannomas) using archival formalin-fixed paraffin-embedded tissues. Expression of PD-L1 was considered positive in cases with > 5% membranous staining of tumor cells, in accordance with previously published biomarker studies. PD-L1 expression in tumor cells (using the SP142 and E1L3N clones, respectively) was assessed as positive in plexiform neurofibromas (6/6 and 5/6) dermal neurofibromas (8/10 and 6/10), schwannomas (7/10 and 10/10), and meningiomas (4/10 and 2/10). Sparse to moderate presence of CD68, CD3, or CD8 positive TILs was found in 36 (100%) of tumor specimens. Our findings indicate that adaptive resistance to cell-mediated immunity may play a major role in the tumor immune microenvironment of NF1 and NF2-associated tumors. Expression of PD-L1 on tumor cells and the presence of TILs suggest that these tumors might be responsive to immunotherapy with immune checkpoint inhibitors, which should be explored in clinical trials for NF patients.

CTLA-4 immune checkpoint blockade is clinically effective in a subset of patients with metastatic melanoma. We identify a subcluster of MAGE-A cancer-germline antigens, located within a narrow 75 kb region of chromosome Xq28, that predicts resistance uniquely to blockade of CTLA-4, but not PD-1. We validate this gene expression signature in an independent anti-CTLA-4-treated cohort and show its specificity to the CTLA-4 pathway with two independent anti-PD-1-treated cohorts. Autophagy, a process critical for optimal anti-cancer immunity, has previously been shown to be suppressed by the MAGE-TRIM28 ubiquitin ligase in vitro. We now show that the expression of the key autophagosome component LC3B and other activators of autophagy are negatively associated with MAGE-A protein levels in human melanomas, including samples from patients with resistance to CTLA-4 blockade. Our findings implicate autophagy suppression in resistance to CTLA-4 blockade in melanoma, suggesting exploitation of autophagy induction for potential therapeutic synergy with CTLA-4 inhibitors.