Ian McCaffery

PD-L1 Immunohistochemistry Assays for Lung Cancer: Results from Phase 1 of the Blueprint PD-L1 IHC Assay Comparison Project

Introduction: The Blueprint Programmed Death Ligand 1 (PD‐L1) Immunohistochemistry (IHC) Assay Comparison Project is an industrial‐academic collaborative partnership to provide information on the analytical and clinical comparability of four PD‐L1 IHC assays used in clinical trials. Methods: A total of 39 NSCLC tumors were stained with four PD‐L1 IHC assays (22C3, 28‐8, SP142, and SP263), as used in the clinical trials. Three experts in interpreting their respective assays independently evaluated the percentages of tumor and immune cells staining positive at any intensity. Clinical diagnostic performance was assessed through comparisons of patient classification above and below a selected expression cutoff and by agreement using various combinations of assays and cutoffs. Results: Analytical comparison demonstrated that the percentage of PD‐L1–stained tumor cells was comparable when the 22C3, 28‐8, and SP263 assays were used, whereas the SP142 assay exhibited fewer stained tumor cells overall. The variability of immune cell staining across the four assays appears to be higher than for tumor cell staining. Of the 38 cases, 19 (50.0%) were classified above and five (13%) were classified below the selected cutoffs of all assays. For 14 of the 38 cases (37%), a different PD‐L1 classification would be made depending on which assay/scoring system was used. Conclusions: The Blueprint PD‐L1 IHC Assay Comparison Project revealed that three of the four assays were closely aligned on tumor cell staining whereas the fourth showed consistently fewer tumor cells stained. All of the assays demonstrated immune cell staining, but with greater variability than with tumor cell staining. By comparing assays and cutoffs, the study indicated that despite similar analytical performance of PD‐L1 expression for three assays, interchanging assays and cutoffs would lead to “misclassification” of PD‐L1 status for some patients. More data are required to inform on the use of alternative staining assays upon which to read different specific therapy‐related PD‐L1 cutoffs.

Randomized Phase Ib/II Trial of Rilotumumab or Ganitumab With Panitumumab Versus Panitumumab Alone in Patients With Wild-Type KRAS Metastatic Colorectal Cancer

Purpose: Panitumumab, a fully human anti-epidermal growth factor receptor monoclonal antibody (mAb), has demonstrated efficacy in patients with wild-type KRAS metastatic colorectal cancer (mCRC). Rilotumumab and ganitumab are investigational, fully human mAbs against hepatocyte growth factor (HGF)/scatter factor and IGF1R, respectively. Here we evaluate combining rilotumumab or ganitumab with panitumumab in previously treated patients with wild-type KRAS mCRC. Experimental Design: Part 1 was a phase Ib dose-finding study of panitumumab plus rilotumumab. The primary endpoint was the incidence of dose-limiting toxicities (DLT). Part 2 was a randomized phase II trial of panitumumab in combination with rilotumumab, ganitumab, or placebo. The primary endpoint was objective response rate (ORR); safety, progression-free survival (PFS), and overall survival (OS) were secondary endpoints. Archival tissue specimens were collected for exploratory correlative work. Results: In part 1, no DLTs were reported. A recommended phase II dose of 10 mg/kg rilotumumab was selected. In part 2, for the panitumumab plus rilotumumab (n = 48), panitumumab plus ganitumab (n = 46), and panitumumab plus placebo arms (n = 48), the ORRs were 31%, 22%, and 21%, respectively. The median PFS was 5.2, 5.3, and 3.7 months and median OS 13.8, 10.6, and 11.6 months, respectively. Adverse events were tolerable. Exploratory biomarker analyses, including MET and IGF-related protein expression, failed to indicate conclusive predictive evidence on efficacy endpoints. Conclusions: Panitumumab plus rilotumumab met the prespecified criterion for improvement in ORR whereas ganitumab did not. This is the first study to suggest a benefit for combining an HGF inhibitor (rilotumumab) with panitumumab in previously treated patients with wild-type KRAS mCRC. Clin Cancer Res; 20(16); 4240–50. ©2014 AACR.

Effect of Fluorouracil, Leucovorin, and Oxaliplatin With or Without Onartuzumab in HER2-Negative, MET-Positive Gastroesophageal Adenocarcinoma: The METGastric Randomized Clinical Trial

Importance Dysregulation of the mesenchymal-epithelial transition (MET) signaling pathway is associated with poor prognosis in gastroesophageal adenocarcinoma (GEC). We report results of METGastric, a phase 3 trial of the MET inhibitor onartuzumab plus standard first-line chemotherapy for human epidermal growth factor receptor 2 (HER2)-negative, MET-positive, advanced GEC. Objective To determine whether the addition of onartuzumab to first-line fluorouracil, leucovorin, and oxaliplatin (mFOLFOX6) improves efficacy compared with mFOLFOX6 plus placebo in HER2-negative, MET-positive GEC. Design, Setting, and Participants Randomized, double-blind, multicenter trial conducted from November 2012 to March 2014. Patients were 18 years or older with an adenocarcinoma of the stomach or gastroesophageal junction with metastatic disease not amenable for curative therapy. Tumor samples were centrally tested for MET expression using Ventana anti-Total c-MET (SP44) rabbit monoclonal antibody, HER2 status, and Lauren histologic subtype. MET-positive tumors were defined as at least 50% of tumor cells showing weak, moderate, and/or strong staining intensity (MET 1+/2+/3+, respectively) by immunohistochemistry. Interventions Patients with HER2-negative, MET-positive GEC were enrolled and randomized 1:1 to receive mFOLFOX6 with or without onartuzumab (10 mg/kg). Main Outcomes and Measures Co–primary end points: overall survival in the intent-to-treat (ITT) population and in patients with MET 2+/3+ GEC. Secondary end points: progression-free survival (PFS), overall response rate (ORR), and safety. Results Enrollment was stopped early due to sponsor decision, which was agreed with an independent data monitoring committee. At the data cutoff (April 25, 2014) there were 562 patients in the ITT population (nu2009=u2009283 placebo plus mFOLFOX6 [median age, 58 y; 65% male]; nu2009=u2009279 onartuzumab plus mFOLFOX6 [median age, 60 y; 67% male]); 109 (38.5%) and 105 (37.6%) of the ITT population were MET 2+/3+, respectively. Addition of onartuzumab to mFOLFOX6 did not significantly improve OS, PFS, or ORR vs placebo plus mFOLFOX6 in the ITT (OS hazard ratio [HR], 0.82; 95% CI, 0.59-1.15; Pu2009=u2009.24; PFS HR, 0.90; 95% CI, 0.71-1.16; Pu2009=u2009.43; ORR, 46.1% vs 40.6%) or MET 2+/3+ populations (OS HR, 0.64; 95% CI, 0.40-1.03; Pu2009=u2009.06; PFS HR, 0.79; 95% CI, 0.54-1.15; Pu2009=u2009.22; ORR, 53.8% vs 44.6%). Safety was as expected for onartuzumab. Conclusions and Relevance Addition of onartuzumab to first-line mFOLFOX6 did not significantly improve clinical benefits in the ITT or MET 2+/3+ populations. Trial Registration clinicaltrials.gov Identifier: NCT01662869

Abstract CT119: CPI-444, an oral adenosine A2a receptor (A2aR) antagonist, demonstrates clinical activity in patients with advanced solid tumors

Background: Accumulation of extracellular adenosine in the tumor microenvironment activates A2aR suppressing anti-tumor immunity. CPI-444 is an oral, selective A2aR antagonist with single agent (SA) antitumor efficacy in mouse models, and the addition of anti-PD-1/PD-L1 antibodies leads to synergistic anti-tumor activity. CPI-444 was well-tolerated in previous clinical trials in the non-oncology setting. This phase 1/1b open-label clinical trial uses a 2-step adaptive design to evaluate CPI-444 alone and in combination with atezolizumab (atezo, Tecentriq®) in patients(pts) with advanced cancers. Preliminary efficacy and safety results in the dose selection phase (Step 1) are reported. This is the first report of adenosine inhibition as a treatment for cancer. Methods: Adult pts who have failed up to 5 standard therapies with advanced solid tumors were enrolled. In Step 1, pts were randomized 1:1:1:1 to 1 of 4 dose cohorts (28 days/cycle) including 3 SA cohorts (100mg BID x 14 days(d), 100mg BID x 28d and 200 mg QD x 14d) or combined with atezo (CPI-444 50mg or 100 mg BID x 14d + atezo 840mg IV q2 weeks). Primary objectives: safety and efficacy and defining the optimal dose and schedule of CPI-444. Results: 48 pts were enrolled in Step 1; 47 received treatment. Median age was 65 years (range, 36-84).Tumor types enrolled were: non- small cell lung cancer(NSCLC, n=10), triple negative breast cancer (TNBC,n=10),melanoma(MEL,n=7), urothelial bladder cancer(UBC,n=6), renal cell cancer(RCC,n=5), MSI-H colorectal cancer(CRC,n=4), head and neck cancer (SCCHN, n=3)and prostate cancer (n=2). Median number of prior systemic regimens was 4(range, 1-5). Twenty-four pts received prior anti PD-1/PD-L1 therapy. One pt in the combination cohort had reversible grade 3 autoimmune hemolytic anemia which was the only DLT observed. Biomarker analyses defined the optimal dose of CPI-444 as 100 mg bid x 28 days. With a median follow-up time of 12 weeks(range, 2-32), the overall disease control rate (DC defined as CR, PR or SD) was 45% per RECIST. Nineteen pts had SD;15 pts received SA CPI-444. Two pts had a PR; both received SA. Of 5 RCC pts enrolled, 4 had DC (1 PR, 3 SD). Of these 4 RCC pts, 3 are receiving SA CPI-444 including the patient with PR. These 4 RCC pts remain on treatment with 2 pts on treatment for > 30 weeks. Of 7 MEL pts, 1 pt receiving SA had a PR and 2 had SD. SD was observed in 5/10 NSCLC pts, 4/10 TNBC pts, as well as 2/6 UBC pts and 1 pt each with CRC, SCCHN and prostate cancer. The proportion of pts with DC were similar for pts treated with CPI-444 alone and for pts treated with CPI-444 combined with atezo. 9/18(50%) pts who were naive to anti-PD-1/PD-L1 treatment achieved DC as well as 10/24(42%) of pts who were resistant/ refractory to anti-PD1/PDL1 therapy. The most common (≥ 10% of pts) adverse events related to study drug were Grade 1 or 2 nausea (13%) and fatigue (19%). Conclusion: Inhibition of adenosine signaling through the A2aR results in anti-tumor activity in pts with advanced solid tumors. Responses are observed in multiple histologies both as a SA and in combination with atezo and in pts naive or resistant/refractory to anti-PD-1/PD-L1 therapy. The optimal dose is 100 mg bid continuous. Enrollment in Step 2, evaluating disease-specific cohorts, is ongoing. Citation Format: Leisha Emens, John Powderly, Lawrence Fong, Joshua Brody, Patrick Forde, Matthew Hellmann, Brett Hughes, Shivaani Kummar, Sherene Loi, Jason Luke, Daruka Mahadevan, Benjamin Markman, Ian McCaffery, Richard Miller, Ginna Laport. CPI-444, an oral adenosine A2a receptor (A2aR) antagonist, demonstrates clinical activity in patients with advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT119. doi:10.1158/1538-7445.AM2017-CT119

Abstract B001: Development of a PD-L1 companion diagnostic IHC assay (SP142) for atezolizumab

Background: Understanding of immune tolerance mechanisms of cancer has prompted the development of cancer immunotherapies such as atezolizumab (anti-PD-L1, MPDL3280A). Robust, durable responses have been observed, leading to Breakthrough status designation by the FDA for atezolizumab for previously treated NSCLC and bladder cancer (UBC) patients. Roche/Ventana have developed a companion diagnostic (CDx) for atezoliziumab using a robust immunohistochemistry (IHC) assay and antibody clone (SP142), optimized to detect PD-L1 expression in both tumor cells (TC) and tumor-infiltrating immune cells (IC). Here we describe the characteristics of the SP142 assay, PD-L1 expression patterns observed by immunohistochemistry in TC and IC compartments, and their association with clinical efficacy for NSCLC and UBC patients. Methods: The anti-human PD-L1 rabbit monoclonal antibody SP142 was optimized for detection of both TC and IC expression of PD-L1 with the Ventana OptiView DAB IHC Detection Kit on the automated BenchMark ULTRA platform. The VENTANA PD-L1 (SP142) CDx assay was validated for use in formalin-fixed, paraffin-embedded samples of NSCLC and UBC in a series of studies addressing sensitivity, specificity, robustness, and precision. Formalin fixed, paraffin embedded tumor specimens were obtained from patients prescreened and/or enrolled into Genentech Ph I study PCD4989g, and PD-L1 expression was measured using the SP142 assay and PCR gene expression assays. Results: The SP142 assay met pre-defined acceptance criteria for TC and IC assessment of PD-L1 expression in NSCLC and UBC tumors, including >90% inter-reader concordance between pathologist readers. Rapid and durable responses were observed in the Ph I study (PCD4989g), and correlated with PD-L1 expression patterns observed by immunohistochemistry in TC and IC. In the same Ph I study (PCD4989g), PD-L1 expression as measured by PCR did not demonstrate the same predictive value as observed for IHC. Conclusions: The PD-L1 IHC (SP142) CDx is a robust assay to measure PD-L1 expression in both IC and TC. Further, the high reproducibility of results between pathologists shows that the scoring algorithms in UBC and NSCLC are precise, reproducible, and practical in the diagnostic setting. The results indicate that favorable atezolizumab efficacy for UBC is strongly associated with higher IC levels as assessed by the sensitive and specific PD-L1 IHC (SP142) CDx assay. In NSCLC, favorable atezolizumab efficacy is associated with tumors expressing either high TC or high IC levels by the PD-L1 IHC (SP142) CDx assay. These data support the predictive value of tumor PD-L1 levels by IHC for NSCLC and UBC patients receiving atezoliziumab. Citation Format: Zachary S. Boyd, Dustin Smith, Brian Baker, Bharathi Vennapusa, Hartmut Koeppen, Marcin Kowanetz, Sanjeev Mariathasan, Jean-Marie Bruey, Howard Mackey, Gregg Fine, Simonetta Mocci, Priti Hegde, J. Andrew Williams, Ian McCaffery. Development of a PD-L1 companion diagnostic IHC assay (SP142) for atezolizumab. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr B001.

Abstract PR04: CPI-444: A potent and selective inhibitor of A2AR induces antitumor responses alone and in combination with anti-PD-L1 in preclinical and clinical studies

Elevated extracellular adenosine in the tumor microenvironment generates an immunosuppressive niche that promotes tumor growth and metastasis that is mediated via A2A receptor (A2AR) on immune cells. CPI-444 is a potent, oral, selective A2AR antagonist that has been well tolerated in Ph 1/1b studies in non-oncology indications. CPI-444 is being investigated in a Ph 1b study in solid tumors as a single agent and in combination with the anti-PD-L1 antibody atezolizumab. In preclinical studies, daily treatment of the syngeneic mouse model MC38 with CPI-444 (1, 10, 100 mg/kg) led to dose-dependent inhibition of tumor growth, leading to tumor elimination in ∼30% of treated mice. Combining CPI-444 (100 mg/kg, qd, 14 days) with anti-PD-L1 (200 μg, 3qw, 4 doses) treatment in MC38 models synergistically inhibited tumor growth and eliminated tumors in 90% of treated mice. When cured mice were later re-challenged with MC38 cells, tumor growth was rejected in 100% of challenged mice, indicating that CPI-444 induced systemic anti-tumor immune memory. CD8+ T cell depletion abrogated the efficacy of CPI-444 treatment as a single agent as well as in combination with anti-PD-L1, demonstrating a role for CD8+ T cells in mediating primary and secondary immune responses. Anti-tumor efficacy of CPI-444 ± anti-PD-L1 was associated with increased CD8+ cell infiltration and activation in MC38 tumor tissues, and a corresponding rise in PD-1 expression on CD8+ T cells in the spleen. Additionally, levels of immune checkpoints were modulated by treatment with CPI-444, including GITR, OX40, and LAG3 on tumor infiltrating lymphocytes and circulating T cells, suggesting a broad role for adenosine mediated immunosuppression. Based on these results and others, we have initiated a Phase 1b clinical trial to examine safety, tolerability, biomarkers, and preliminary efficacy of CPI-444 as a single agent and in combination with the anti-PD-L1 antibody, atezolizumab, in patients with non-small cell lung, melanoma, renal, triple negative breast, and other (head and neck, colorectal [MSI-H], bladder) tumors. Peripheral blood and tumor biopsies are collected pre- and post-treatment for biomarker analysis of adenosine pathway expression and activity, immune cell activation and tumor infiltration, and mutational burden. To demonstrate CPI-444 blockade of A2AR, a functional signaling assay was developed. Peripheral blood samples from treated patients were stimulated ex vivo with the adenosine analog NECA and CREB phosphorylation was quantified using flow cytometry in B and T cells. Following 14 days of CPI-444 treatment, NECA signaling was robustly inhibited at the doses selected for the Ph1b study in both the CPI-444 single agent and combination cohorts. In summary, this shows that CPI-444 induces anti-tumor immunity in mouse tumor models and inhibits adenosine signaling in lymphocytes of treated humans. This is the first demonstration of immune modulation in cancer patients receiving an adenosine antagonist. Evaluation of patient clinical responses and additional biomarkers are ongoing. Citation Format: Stephen Willingham, Andrew Hotson, Po Ho, Carmen Choy, Ginna Laport, Ian McCaffery, Richard Miller. CPI-444: A potent and selective inhibitor of A2AR induces antitumor responses alone and in combination with anti-PD-L1 in preclinical and clinical studies [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr PR04.

Abstract 5593: Inhibition of A2AR induces anti-tumor immunity alone and in combination with anti-PD-L1 in preclinical and clinical studies

Adenosine signaling via A2A receptor (A2AR) on immune cells suppresses anti-tumor immunity and limits the efficacy of immunotherapy, chemotherapy, CAR-T, and vaccines. CPI-444 is a potent and selective oral A2AR antagonist. Daily treatment of mice with CPI-444 led to dose-dependent inhibition of tumor growth in multiple syngeneic tumor models. Combining CPI-444 with anti-PD-L1 treatment synergistically eliminated tumors in up to 90% of treated mice, including restoration of immune responses in models that are poorly responsive to anti-PD-1 or anti-PD-L1 monotherapy. We have initiated a Phase 1/1b clinical trial to examine safety, tolerability, biomarkers, and preliminary efficacy of CPI-444 as a single agent and in combination with the anti-PD-L1 antibody, atezolizumab, in patients with non-small cell lung, melanoma, renal, triple negative breast, and other (bladder, prostate, head and neck, colorectal) tumors. Step 1 of the trial focused on determining the optimal dose and schedule for CPI-444; Step 2 is currently evaluating the efficacy of optimal CPI-444 dosing alone and with atezolizumab. In 48 patients treated in Step 1, CPI-444 was well tolerated with 1 Grade 3 or 4 treatment related adverse events. Preliminary evidence of clinical activity was observed in patients treated with single agent CPI-444, including patients who previously failed anti-PD-1 therapy. A pCREB-based pharmacodyamic assay showed that 100 mg, BID dose of CPI-444 resulted in a complete, sustained inhibition of A2AR on circulating immune cells. CPI-444 treatment alone or in combination with atezolizumab resulted in increased frequency of circulating CD8+PD-1+ cells and memory/effector subsets of CD4+ and CD8+ T cells. Substantial changes in TCR repertoire (Morisita Index Citation Format: Stephen Willingham, Andrew Hotson, Po Ho, Carmen Choy, Kim Walter, Erik Yusko, Sharon Benzeno, Ginna Laport, Richard Miller, Ian McCaffery. Inhibition of A2AR induces anti-tumor immunity alone and in combination with anti-PD-L1 in preclinical and clinical studies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5593. doi:10.1158/1538-7445.AM2017-5593

Abstract 5579: Strategic inhibition of adenosine A2A receptor (A2AR) by CPI-444 improves CD8+:Treg ratios and enhances T-cell killing of a HER-2/neu expressing murine tumor

It has been demonstrated that a higher CD8+ to CD4+FoxP3+ T regulatory cells (Tregs) ratio coincides with improved therapeutic outcomes for patients receiving immunotherapies in the clinic. The last several years of research have drawn attention to many such therapeutics and strategies. Adenosine is an abundant extracellular signaling molecule in the tumor microenvironment (TME) of many cancers. Signal transduction through the GPCR A2AR enhances the immunosuppressive activity of Tregs while simultaneously attenuating tumor-specific CD4+/CD8+ T cells. We have evaluated the appropriate coordination and dosing for a small-molecule inhibitor of A2AR in a Her-2/neu expressing murine model of breast cancer. We have demonstrated its capacity to augment existing therapeutic strategies in this tolerant model. To test our hypotheses on the ability of the small molecule to work in concert with existing therapeutics, we tested the role of CPI-444 when given with a T cell-inducing vaccine. Neu-expressing mammary tumor bearing HER-2/neu transgenic (Neu-N) mice were administered combinations of low-dose cyclophosphamide (Cy) to deplete Tregs, followed one day later with a granulocyte-macrophage colony-stimulating factor (GM-CSF) and neu-expressing whole cell vaccine (GVAX). The day following administration of GVAX, mice received adoptively transferred high-avidity naive neu-specific CD8+ T cells intravenously one day after vaccination. Administration of specific components in this strategy (i.e. Cy, GVAX, adoptive transfer) were altered to gain insight into the mechanistic effects of CPI-444 in vivo through analysis of tumor progression, tumor clearance, and flow cytometric analysis of the TIL. Mice treated with the A2AR inhibitor or the vehicle control were administered each by oral gavage daily for 14 days (survival) or until 4 days post-adoptive transfer (TIL) at the peak infiltrate time. Of the strategies tested, Cy, followed by concomitant administration of GVAX with 100mg/kg of CPI-444 for 14 days, and a single adoptive therapy treatment provided a 55% overall survival (OS) compared with 0%-20% OS in vehicle controls (P Citation Format: Blake A. Scott, Todd Armstrong, Stephen Willingham, Ian McCaffery, Elizabeth M. Jaffee. Strategic inhibition of adenosine A2A receptor (A2AR) by CPI-444 improves CD8+:Treg ratios and enhances T-cell killing of a HER-2/neu expressing murine tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5579. doi:10.1158/1538-7445.AM2017-5579

Abstract 5598: Adenosine signaling through A2AR limits the efficacy of anti-CTLA4 and chemotherapy in preclinical models

Elevated levels of extracellular adenosine within the tumor microenvironment create an immunosuppressive niche that promotes tumor growth and metastasis. Adenosine signaling via the A2A receptor (A2AR) on immune cells suppresses anti-tumor immunity and has been shown to limit the efficacy of immunotherapies such as anti-PD-L1 or anti-PD-1 monoclonal antibodies (mAbs). CPI-444 is a potent and selective oral A2AR antagonist that is currently being investigated in Phase 1/1b clinical trials alone and in combination with an anti-PD-L1 antibody (Atezolizumab) in selected solid tumors. New preclinical data suggests that combining CPI-444 with anti-CTLA-4 mAbs as well as chemotherapy treatment are also promising therapeutic strategies in solid tumors, suggesting a broad role for adenosine as an immune suppressive mechanism. The efficacy of CPI-444 + anti-CTLA-4 mAb treatment was evaluated in MC38 and CT26 syngeneic mouse tumor models. In CT26, combination treatment eliminated established tumors in up to 90% of mice approximately 2 weeks after treatment was initiated. In MC38, combination CPI-444 and anti-CTLA-4 mAb treatment prolonged survival of 80% of mice compared to only 40% of mice that received CPI-444 or anti-CTLA-4 mAbs alone. The effect of CPI-444 + anti-CTLA-4 treatment on T-cell proliferation, T cell activation, and TREG function will be discussed. Chemotherapy releases adenosine and ATP into the tumor microenvironment (TME). Multiple chemotherapies have also been shown to up-regulate the ecto-enzymes CD39 and CD73 that produce adenosine and further suppress immune function. In the MC38 model, CPI-444 treatment synergized with doxorubicin and eliminated established tumors 80% of treated mice. CPI-444 treatment was also synergistic with cyclophosphamide, inhibiting the growth of RENCA tumors, a model that is considered resistant to chemotherapy. Ongoing studies are evaluating the effect of CPI-444 + chemotherapy on tumor infiltrating lymphocyte localization, activation, and expression of CD73 and CD39. These results suggest that blockade of the adenosine signaling pathway may be vital for enhancing anti-tumor responses in solid tumors that show an incomplete response to anti-CTLA4 therapy or chemotherapy. Citation Format: Po Ho, Meng-Yin Hsieh, Andrew Hotson, Richard Miller, Ian McCaffery, Stephen Willingham. Adenosine signaling through A2AR limits the efficacy of anti-CTLA4 and chemotherapy in preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5598. doi:10.1158/1538-7445.AM2017-5598

Abstract A017: PD-L1 as a predictive biomarker for atezolizumab (MPDL3280A; anti-PDL1) in non-small cell lung cancer (NSCLC)

Background: Programmed death ligand-1 (PD-L1), a ligand for PD-1 and B7.1, is broadly expressed on tumor cells (TC) and tumor-infiltrating immune cells (IC) in many human cancers. PD-L1 expression on either TC or IC can negatively regulate antitumor T-cell function within the tumor microenvironment (TME). Consistent with this, the ORR, PFS and OS benefit of atezolizumab (atezo) across PhI and PhII studies appeared to correlate with increasing baseline PD-L1 expression levels on TC and/or IC. Therefore, we explored the biologic reasons for PD-L1 expression on TC and IC, the association with response to atezo and the intrapatient heterogeneity of PD-L1 expression in NSCLC. Methods: Tumor specimens were obtained from patients (pts) prescreened and/or enrolled in NSCLC atezo trials (PhI PCD4989g, PhII POPLAR and FIR [n=1360]) and from pts treated at MSKCC (n=39). Samples included 14 synchronous and 106 metachronous pairs collected in FIR or at MSKCC. Using the SP142 IHC assay, which has been optimized to detect PD-L1 on both TC and IC, PD-L1 expression was scored at 4 levels (TC0-3 and IC0-3) based on increasing expression. A subset of samples was further characterized by histopathologic review and gene expression by RNAseq. CD8 expression (clone C8/144B) was assessed in the tumor center, invasive margin and periphery by IHC. Results: PD-L1 was expressed on IC only, on TC only or on both TC and IC within the TME. Tumors with the highest (TC3 or IC3), moderate/high (TC2/3 or IC2/3) and any (TC1/2/3 or IC1/2/3) PD-L1 expression represented ≈15%, ≈38% and ≈70% of NSCLC, respectively. PD-L1 expression was similar across all paired synchronous and metachronous tissues. At the TC3 or IC3 cutoff, PD-L1 status remained unchanged in 86% of paired synchronous specimens and in 78% of metachronous pairs. Analysis of PD-L1 expression patterns revealed the existence of exclusive TC and IC subpopulations at each PD-L1 expression level, unique to NSCLC and not seen in other cancers, e.g. UBC. Strikingly, TC3 and IC3 tumors represented 2 distinct populations, with Conclusions: These data demonstrated that NSCLC has unique PD-L1 expression patterns. High expression of PD-L1 on TC and/or IC in NSCLC confers sensitivity to atezo, despite exhibiting distinct immunologic profiles. These results further our understanding of how atezo promotes responses in tumors expressing PD-L1 on TC and/or IC and emphasizes the need to assess PD-L1 on both TC and IC in NSCLC. In addition, intrapatient heterogeneity in PD-L1 expression was relatively low in both synchronous and metachronous tissues, indicating that various types of tumor samples (e.g. primary or metastatic, fresh or archival) can be reliably used to assess PD-L1 expression with the SP142 assay. Citation Format: Marcin Kowanetz, Hartmut Koeppen, Wei Zou, Sanjeev Mariathasan, Matthew Hellmann, Mark Kockx, Colombe Chappey, Edward Kadel, Dustin Smith, Natasha Miley, Vincent Leveque, Roel Funke, Alan Sandler, Ian McCaffery, Lukas Amler, Daniel Chen, Priti Hegde. PD-L1 as a predictive biomarker for atezolizumab (MPDL3280A; anti-PDL1) in non-small cell lung cancer (NSCLC). [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A017.