Dual Biomarker Signature Holds Predictive Promise for Response to Anti-PD-L1 Therapy in NSCLC

Excerpt:

“Recent research suggests that the presence of PD-L1–positive and CD8+ cells may be useful for predicting responses in patients with non-small cell lung cancer (NSCLC) who have been treated with durvalumab (MEDI4736).

“Sonja Althammer, PhD, presented research on the association between improved survival rates to treatment with durvalumab and high CD8+ and PD-L1+ cell densities during a late-breaking abstract session at the Society for Immunotherapy of Cancer (SITC) 21st Annual Meeting & Associated Programs.”

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Frequency of Certain Immune Cells in Blood May Predict Metastatic Melanoma Response to Pembrolizumab

“Among patients with metastatic melanoma treated with the immunotherapy drug pembrolizumab (Keytruda), those whose cancer responded to the treatment had a higher frequency of immune cells called T cells that were positive for the proteins CD8, PD-1, and Bim (CD8+PD-1+Bim+ T cells) in blood samples taken immediately before starting pembrolizumab than those who had disease progression, according to data presented at the CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference, held Sept. 16–19.

“Pembrolizumab, which targets the protein PD-1, was approved by the U.S. Food and Drug Administration for treating metastatic melanoma in September 2014. Some patients with metastatic melanoma have remarkable responses to pembrolizumab, whereas others do not respond at all, according to Roxana S. Dronca, MD, a medical oncology consultant and assistant professor of oncology at the Mayo Clinic in Rochester, Minnesota.”


CD137 Accurately Identifies and Enriches for Naturally-Occurring Tumor-Reactive T Cells in Tumor

“Purpose: Up-regulation of CD137 (4-1BB) on recently activated CD8+ T-cells has been used to identify rare viral or tumor antigen-specific T-cells from peripheral blood. Here, we evaluated the immunobiology of CD137 in human cancer and the utility of a CD137-positive separation methodology for the identification and enrichment of fresh tumor-reactive tumor-infiltrating lymphocytes (TILs) or tumor-associated lymphocytes (TAL) from ascites for use in adoptive immunotherapy. Experimental Design: TILs from resected ovarian cancer or melanoma were measured for surface CD137expression directly or after overnight incubation in the presence of tumor cells and homeostatic cytokines. CD137pos TILs were sorted and evaluated for anti-tumor activity in vitro and in vivo. Results: Fresh ovarian TILs and TALs naturally expressed higher levels of CD137 than circulating T-cells. An HLA-dependent increase in CD137 expression was observed following incubation of fresh enzyme-digested tumor or ascites in IL-7 and IL-15 cytokines, but not IL-2. Enriched CD137pos TILs, but not PD-1pos or PD-1neg CD137neg cells, possessed autologous tumor-reactivity in vitro and in vivo. In melanoma studies, all MART-1-specific CD8+ TILs up-regulated CD137 expression after incubation with HLA-matched, MART-expressing cancer cells and antigen-specific effector function was restricted to the CD137pos subset in vitro. CD137pos TILs also mediated superior anti-tumor effects in vivo, compared to CD137neg TILs. Conclusions: Our findings reveal a role for the TNFR-family member CD137 in the immunobiology of human cancer where it is preferentially expressed on tumor-reactive subset of TILs, thus rationalizing its agonistic engagement in vivo and its use in TIL selection for adoptive immunotherapy trials.”


Lysophosphatidic Acid Inhibits CD8 T-cell Activation and Control of Tumor Progression

“CD8 T lymphocytes are able to eliminate nascent tumor cells through a process referred to as immunosurveillance. However, multiple inhibitory mechanisms within the tumor microenvironment have been described that impede tumor rejection by CD8 T cells, including increased signaling by inhibitory receptors. Lysophosphatidic acid (LPA) is a bioactive lysophospholipid that has been shown repeatedly to promote diverse cellular processes benefiting tumorigenesis. Accordingly, the exaggerated expression of LPA and LPA receptors is a common feature of diverse tumor cell lineages and can result in elevated systemic LPA levels. LPA is recognized by at least six distinct G protein–coupled receptors, several of which are expressed by T cells, although the precise function of LPA signaling in CD8 T-cell activation and function has not been defined. Here, we show that LPA signaling via the LPA5 receptor expressed by CD8 T cells suppresses antigen receptor signaling, cell activation, and proliferation in vitro and in vivo. Importantly, in a mouse melanoma model tumor-specific CD8 T cells that are LPA5-deficient are able to control tumor growth significantly better than wild-type tumor-specific CD8 T cells. Together, these data suggest that the production of LPA by tumors serves not only in an autocrine manner to promote tumorigenesis, but also as a mechanism to suppress adaptive immunity and highlights a potential novel target for cancer treatment.”


Anti-CCR4 mAb Selectively Depletes Effector-Type FoxP3+CD4+ Regulatory T Cells, Evoking Antitumor Immune Responses in Humans

“Regulatory T (Treg) cells expressing the transcription factor FOXP3 play a critical role in suppressing antitumor immune responses. Here we found that, compared with peripheral blood T cells, tumor-infiltrating T cells contained a higher frequency of effector Tregs, which are defined as FOXP3hi and CD45RA, terminally differentiated, and most suppressive. Effector Treg cells, but not FOXP3lo and CD45RA+ naïve Treg cells, predominantly expressed C-C chemokine receptor 4 (CCR4) in both cancer tissues and peripheral blood. In vivo or in vitro anti-CCR4 mAb treatment selectively depleted effector Treg cells and efficiently induced tumor-antigen-specific CD4+ and CD8+ T cells. Thus, cell-depleting anti-CCR4 mAb therapy is instrumental for evoking and enhancing tumor immunity in humans via selectively removing effector-type FOXP3+ Treg cells.”


Particle Shape Dependence of CD8+ T cell Activation by Artificial Antigen Presenting Cells

“Previous work developing particle-based acellular, artificial antigen presenting cells (aAPCs) has focused exclusively on spherical platforms. To explore the role of shape, we generated ellipsoidal PLGA microparticles with varying aspect ratios (ARs) and synthesized aAPCs from them. The ellipsoidal biomimetic aAPCs with high-AR showed significantly enhanced in vitro and in vivo activity above spherical aAPCs with particle volume and antigen content held constant. Confocal imaging indicates that CD8+ T cells preferentially migrate to and are activated by interaction with the long axis of the aAPC. Importantly, enhanced activity of high-AR aAPCs was seen in a mouse melanoma model, with high-AR aAPCs improving melanoma survival compared to non-cognate aAPCs (p = 0.004) and cognate spherical aAPCs (p = 0.05). These findings indicate that particle geometry is a critical design criterion in the generation of aAPCs, and may offer insight into the essential role of geometry in the interaction between CD8+ T cells and biological APCs.”


Treatment of Malignant Pleural Mesothelioma by Fibroblast Activation Protein-specific Re-directed T cells

Malignant pleural mesothelioma (MPM) results from chronic exposition to asbestos in at least 70% of the cases. Fibroblast activation protein (FAP) is predominantly expressed on the surface of reactive tumor-associated fibroblasts as well as on particular cancer types. Because of its expression on the cell surface, FAP is an attractive target for adoptive T cell therapy. T cells can be re-directed by retroviral transfer of chimeric antigen receptors (CAR) against tumor-associated antigens (TAA) and therefore represent a therapeutic strategy of adoptive immunotherapy.

FAP re-directed CD8+ T cells showed antigen-specific functionality in vitro and in vivo. Furthermore, FAP expression was verified in all MPM histotypes. Therefore, our data support performing a phase I clinical trial in which MPM patients are treated with adoptively transferred FAP-specific re-directed T cells.


Up-Regulation of PD-L1, IDO, and Tregs in the Melanoma Tumor Microenvironment Is Driven by CD8+ T Cells

“Tumor escape from immune-mediated destruction has been associated with immunosuppressive mechanisms that inhibit T cell activation. Although evidence for an active immune response, including infiltration with CD8+ T cells, can be found in a subset of patients, those tumors are nonetheless not immunologically rejected. In the current report, we show that it is the subset of T cell–inflamed tumors that showed high expression of three defined immunosuppressive mechanisms: indoleamine-2,3-dioxygenase (IDO), PD-L1/B7-H1, and FoxP3+ regulatory T cells (Tregs), suggesting that these inhibitory pathways might serve as negative feedback mechanisms that followed, rather than preceded, CD8+ T cell infiltration. Mechanistic studies in mice revealed that up-regulated expression of IDO and PD-L1, as well as recruitment of Tregs, in the tumor microenvironment depended on the presence of CD8+ T cells. The former was driven by interferon-γ and the latter by a production of CCR4-binding chemokines along with a component of induced proliferation. Our results argue that these major immunosuppressive pathways are intrinsically driven by the immune system rather than being orchestrated by cancer cells, and imply that cancer immunotherapy approaches targeting negative regulatory immune checkpoints might be preferentially beneficial for patients with a preexisting T cell–inflamed tumor microenvironment.”


Tumor-Specific T-cell Help Is Associated with Improved Survival in Melanoma

“Despite success with immune checkpoint inhibitors, clinical benefit from cancer vaccines remains elusive. Combined targeting of melanoma-specific CD4+ and CD8+ T-lymphocyte epitopes was associated with improved survival compared with targeting either alone, or when a nonspecific helper epitope was used. We discuss the potential role of antigen-specific CD4 help.”