Yvonne M. Saenger

Perceiving the avidity of T cell activation can be translated into peripheral T cell regulation

The structure recognized by regulatory T cells that enables them to discriminate self from nonself in the periphery is one of the central issues of regulatory T cell biology. A link between immunoregulation and self–nonself discrimination has emerged from experiments showing that Qa-1-restricted CD8+ T cells selectively down-regulate target T cells activated by the intermediate avidity of their own T cell antigen receptor–ligand interactions. Because the peripheral self-reactive T cell repertoire is devoid of high-avidity T cells compared with the foreign-reactive repertoire, as a result of thymic negative selection, the selective down-regulation of intermediate but not high-avidity T cells enables the immune system to suppress autoimmunity without damaging the ongoing immune response to foreign pathogens. However, the molecular mechanism delineating how avidity of T cell activation is perceived by the regulatory T cells has not been elucidated. Here we show that a heat shock peptide (Hsp60sp), coupled with the MHC class Ib molecule Qa-1, is a surrogate target structure that is preferentially expressed at a higher level on the intermediate avidity T cells and specifically recognized by the Qa-1-restricted CD8+ T cells. The biological significance of this observation was confirmed by the ability of Hsp60sp-loaded relevant dendritic cells to induce a Qa-1-restricted CD8+ T cell-mediated protection from autoimmune encephalopathy in the experimental allergic encephalomyelitis model. Thus, perceiving the avidity of T cell activation can be translated into peripheral T cell regulation to discriminate self from nonself in the periphery to maintain self-tolerance.

Current and Emerging Therapies in Metastatic Pancreatic Cancer

Targeted therapies and immunotherapy have changed the face of multiple solid malignancies, including metastatic melanoma and lung cancer, but no such therapies exist for pancreatic ductal adenocarcinoma (PDAC) despite the knowledge of key mutations and an increasing understanding of the tumor microenvironment. Until now, most clinical studies have not been biomarker driven in this highly immunosuppressive and heterogeneous cancer. Ongoing basic and translational studies are better classifying the disease in hopes of identifying critical pathways that distinguish the unique PDAC subtypes, which will lead to personalized therapies. In this review, we discuss the current treatment options for metastatic pancreatic cancer and highlight current ongoing clinical trials, which aim to target the stroma and the immune microenvironment either alone or in combination with standard chemotherapy. Identifying biomarkers and key resistance pathways and targeting these pathways in a personalized manner in combination with chemotherapy are likely to yield a more immediate and durable clinical benefit. Clin Cancer Res; 23(7); 1670–8. ©2017 AACR. See all articles in this CCR Focus section, “Pancreatic Cancer: Challenge and Inspiration.”

Talimogene laherparepvec (T-Vec) for the treatment of melanoma and other cancers

Talimogene laherparepvec (T-Vec) is the first live virus to be approved by the US Food and Drug Administration for the treatment of cancer. This engineered version of herpes simplex virus type 1 (HSV-1) is the product of decades of preclinical work aimed at identifying and modifying aspects of the viral genome involved in virulence and immunogenicity. T-Vec preferentially infects and lyses tumor cells and, in some cases, induces a systemic immune response against the tumor. These properties have translated into significant and durable clinical responses, particularly in advanced melanoma. Many unanswered questions remain, including how to augment these clinical responses and which other tumor types may respond to oncolytic therapy. Here, we review the development of T-Vec, our current understanding of its impact on the tumor immune micro-environment, and its safety and efficacy in clinical trials for melanoma and other cancers.

Disease stabilization with pembrolizumab for metastatic acral melanoma in the setting of autoimmune bullous pemphigoid

BackgroundTo date, patients with pre-existing autoimmune conditions have been excluded from immunotherapy trials out of concern for severe autoimmune exacerbations.Case PresentationWe describe the first case of a patient with metastatic cKIT mutated acral melanoma, brain metastasis, and pre-existing severe autoimmune bullous pemphigoid (BP) with stable and asymptomatic disease 10xa0months after treatment with pembrolizumab. The patient experienced severe BP exacerbation after therapy with ipilimumab requiring systemic immune suppression, but nonetheless pembrolizumab was administered on further disease progression.ConclusionsThis case suggests that pembrolizumab may confer more benefit than risk even in patients with known severe autoimmune conditions who require intermittent systemic immunosuppression.

Immune biomarkers are more accurate in prediction of survival in ulcerated than in non-ulcerated primary melanomas

IntroductionUlcerated melanomas may have a unique biology and microenvironment. We test whether markers of immune infiltration correlate with clinical outcome in ulcerated compared to non-ulcerated primary melanoma tumors.MethodsSixty-two stage II–III cutaneous melanomas, 32 ulcerated and 30 non-ulcerated, were analyzed for tumor-infiltrating lymphocytes (TILs). Immunohistochemistry (IHC) was performed for CD2, a marker previously shown to correlate with overall survival (OS) and recurrence-free survival (RFS) in this patient population. IHC using antibody, VE1, to BRAF V600E was also performed on a subset of 41 tumors to assess the relationship of BRAF mutation to immune markers.ResultsWe found, using Cox regression models, that the presence of TILs was associated with improved OS (pxa0=xa00.034) and RFS (pxa0=xa00.002) in ulcerated melanoma tumors, but not in non-ulcerated melanoma (pxa0=xa00.632, 0.416). CD2 expression also was correlated with improved OS (pxa0=xa00.021) and RFS (pxa0=xa00.001) in ulcerated melanoma, but no relationship was seen in non-ulcerated melanoma (pxa0=xa00.427, 0.682). In this small population, BRAF status did not correlate with TILs or CD2+ count.ConclusionOur data show that immune markers including TILs and CD2 count correlate more closely with survival in ulcerated melanomas than that in non-ulcerated melanomas. We propose that immune biomarkers may be particularly relevant to ulcerated, as compared to non-ulcerated, melanomas and that this merits study in larger populations.

Quality Assessment of Stereotactic Radiosurgery of a Melanoma Brain Metastases Model Using a Mouselike Phantom and the Small Animal Radiation Research Platform

PURPOSEnTo establish a novel preclinical model for stereotactic radiosurgery (SRS) with combined mouselike phantom quality assurance in the setting of brain metastases.nnnMETHODS AND MATERIALSnC57B6 mice underwent intracranial injection of B16-F10 melanoma cells. T1-weighted postcontrast magnetic resonance imaging (MRI) was performed on day 11 after injection. The MRI images were fused with cone beam computed tomography (CBCT) images using the Small Animal Radiation Research Platform (SARRP). The gross tumor volume (GTV) was contoured using the MRI. A single sagittal arc using the 3xa0×xa03xa0mm2 collimator was used to deliver 18xa0Gy prescribed to the isocenter. MRI was performed 7xa0days after radiation treatment, and the dose delivered to the mice was confirmed using 2 mouselike anthropomorphic phantoms: 1 in the axial orientation and the other in the sagittal orientation. The SARRP output was measured using a PTWxa0Farmer type ionization chamber as per the American Association of Physicists in Medicine Task Group report 61, and the H-D curve was generated up to a maximum dose of 30xa0Gy. Irradiated films were analyzed based on optical density distribution and H-D curve.nnnRESULTSnThe tumor volume on day 11, before intervention, was 2.48xa0±xa01.37xa0mm3 in the no-SRS arm versus 3.75xa0±xa01.19xa0mm3 in the SRS arm (NS). In the SRS arm, GTV maximum dose (Dmax) and mean dose were 2048xa0±xa0207 and 1785xa0±xa014xa0cGy. Using the mouselike phantoms, the radiochromic film showed close precision in comparison with projected isodose lines, with a Dmax of 1903.4 and 1972.7xa0cGy, the axial and sagittal phantoms, respectively. Tumor volume 7xa0days after treatment was 7.34xa0±xa08.24xa0mm3 in the SRS arm and 60.20xa0±xa040.4xa0mm3 in the no-SRS arm (P=.009). No mice in the control group survived more than 22xa0days after implantation, with a median overall survival (mOS) of 19xa0days; mOS was not reached in the SRS group, with 1 death noted.nnnCONCLUSIONSnSingle-fraction SRS of 18xa0Gy delivered in a single arc can be delivered accurately with MRI T1-weighted postcontrast-based treatment planning. The mouse like phantom allows for verification of dose delivery and accuracy.

Predicting response to checkpoint inhibitors in melanoma beyond PD-L1 and mutational burden

BackgroundImmune checkpoint inhibitors (ICIs) have changed the clinical management of melanoma. However, not all patients respond, and current biomarkers including PD-L1 and mutational burden show incomplete predictive performance. The clinical validity and utility of complex biomarkers have not been studied in melanoma.MethodsCutaneous metastatic melanoma patients at eight institutions were evaluated for PD-L1 expression, CD8+ T-cell infiltration pattern, mutational burden, and 394 immune transcript expression. PD-L1 IHC and mutational burden were assessed for association with overall survival (OS) in 94 patients treated prior to ICI approval by the FDA (historical-controls), and in 137 patients treated with ICIs. Unsupervised analysis revealed distinct immune-clusters with separate response rates. This comprehensive immune profiling data were then integrated to generate a continuous Response Score (RS) based upon response criteria (RECIST v.1.1). RS was developed using a single institution training cohort (nu2009=u200948) and subsequently tested in a separate eight institution validation cohort (nu2009=u200929) to mimic a real-world clinical scenario.ResultsPD-L1 positivity ≥1% correlated with response and OS in ICI-treated patients, but demonstrated limited predictive performance. High mutational burden was associated with response in ICI-treated patients, but not with OS. Comprehensive immune profiling using RS demonstrated higher sensitivity (72.2%) compared to PD-L1 IHC (34.25%) and tumor mutational burden (32.5%), but with similar specificity.ConclusionsIn this study, the response score derived from comprehensive immune profiling in a limited melanoma cohort showed improved predictive performance as compared to PD-L1 IHC and tumor mutational burden.

The Role of Oncolytic Viruses in the Treatment of Melanoma

Purpose of ReviewOncolytic virotherapy is a new approach to the treatment of cancer and its success in the treatment of melanoma represents a breakthrough in cancer therapeutics. This paper provides a review of the current literature on the use of oncolytic viruses (OVs) in the treatment of melanoma.Recent FindingsTalimogene laherparepvec (T-VEC) is the first OV approved for the treatment of melanoma and presents new challenges as it enters the clinical setting. Several other OVs are at various stages of clinical and pre-clinical development for the treatment of melanoma. Reports from phase Ib-III clinical trials combining T-VEC with checkpoint blockade are encouraging and demonstrate potential added benefit of combination immunotherapy.SummaryOVs have recently emerged as a standard treatment option for patients with advanced melanoma. Several OVs and therapeutic combinations are in development. Immunooncolytic virotherapy combined with immune checkpoint inhibitors is promising for the treatment of advanced melanoma.

Therapeutic Immune Modulation Against Solid Cancers with Intratumoral Poly-ICLC: A Pilot Trial

Purpose: Polyinosinic-polycytidylic acid-poly-l-lysine carboxymethylcellulose (poly-ICLC), a synthetic double-stranded RNA complex, is a ligand for toll-like receptor-3 and MDA-5 that can activate immune cells, such as dendritic cells, and trigger natural killer cells to kill tumor cells. Patients and Methods: In this pilot study, eligible patients included those with recurrent metastatic disease in whom prior systemic therapy (head and neck squamous cell cancer and melanoma) failed. Patients received 2 treatment cycles, each cycle consisting of 1 mg poly-ICLC 3× weekly intratumorally (IT) for 2 weeks followed by intramuscular (IM) boosters biweekly for 7 weeks, with a 1-week rest period. Immune response was evaluated by immunohistochemistry (IHC) and RNA sequencing (RNA-seq) in tumor and blood. Results: Two patients completed 2 cycles of IT treatments, and 1 achieved clinical benefit (stable disease, progression-free survival 6 months), whereas the remainder had progressive disease. Poly-ICLC was well tolerated, with principal side effects of fatigue and inflammation at injection site (<grade 2). In the patient with clinical benefit, IHC analysis of tumor showed increased CD4, CD8, PD1, and PD-L1 levels compared with patients with progressive disease. RNA-seq analysis of the same patients tumor and peripheral blood mononuclear cells showed dramatic changes in response to poly-ICLC treatment, including upregulation of genes associated with chemokine activity, T-cell activation, and antigen presentation. Conclusions: Poly-ICLC was well tolerated in patients with solid cancer and generated local and systemic immune responses, as evident in the patient achieving clinical benefit. These results warrant further investigation and are currently being explored in a multicenter phase II clinical trial (NCT02423863). Clin Cancer Res; 24(20); 4937–48. ©2018 AACR.

IKZF1 Enhances Immune Infiltrate Recruitment in Solid Tumors and Susceptibility to Immunotherapy

Immunotherapies are some of the most promising emergent treatments for several cancers, yet there remains a majority of patients who do not benefit from them due to immune-resistant tumors. One avenue for enhancing treatment for these patients is by converting these tumors to an immunoreactive state, thereby restoring treatment efficacy. By leveraging regulatory networks we previously characterized in autoimmunity, here we show that overexpression of the master regulator IKZF1 leads to enhanced immune infiltrate recruitment and tumor sensitivity to PD1 and CTLA4 inhibitors in several tumors that normally lack IKZF1 expression. This work provides proof of concept that tumors can be rendered susceptible by hijacking immune cell recruitment signals through molecular master regulators. On a broader scale, this work also demonstrates the feasibility of using computational approaches to drive the discovery of novel molecular mechanisms toward treatment.