Amy Peterson

Despite the frequent detection of circulating tumor antigen-specific T cells, either spontaneously or following active immunization or adoptive transfer, immune-mediated cancer regression occurs only in the minority of patients. One theoretical rate-limiting step is whether effector T cells successfully migrate into metastatic tumor sites. Affymetrix gene expression profiling done on a series of metastatic melanoma biopsies revealed a major segregation of samples based on the presence or absence of T-cell-associated transcripts. The presence of lymphocytes correlated with the expression of defined chemokine genes. A subset of six chemokines (CCL2, CCL3, CCL4, CCL5, CXCL9, and CXCL10) was confirmed by protein array and/or quantitative reverse transcription-PCR to be preferentially expressed in tumors that contained T cells. Corresponding chemokine receptors were found to be up-regulated on human CD8(+) effector T cells, and transwell migration assays confirmed the ability of each of these chemokines to promote migration of CD8(+) effector cells in vitro. Screening by chemokine protein array identified a subset of melanoma cell lines that produced a similar broad array of chemokines. These melanoma cells more effectively recruited human CD8(+) effector T cells when implanted as xenografts in nonobese diabetic/severe combined immunodeficient mice in vivo. Chemokine blockade with specific antibodies inhibited migration of CD8(+) T cells. Our results suggest that lack of critical chemokines in a subset of melanoma metastases may limit the migration of activated T cells, which in turn could limit the effectiveness of antitumor immunity.

Although increased circulating tumor antigen-specific CD8(+) T cells can be achieved by vaccination or adoptive transfer, tumor progression nonetheless often occurs through resistance to effector function. To develop a model for identifying mechanisms of resistance to antigen-specific CTLs, poorly immunogenic B16-F10 melanoma was transduced to express the K(b)-binding peptide SIYRYYGL as a green fluorescent protein fusion protein that should be recognized by high-affinity 2C TCR transgenic T cells. Although B16.SIY cells expressed high levels of antigen and were induced to express K(b) in response to IFN-gamma, they were poorly recognized by primed 2C/RAG2(-/-) T cells. A screen for candidate inhibitory ligands revealed elevated PD-L1/B7H-1 on IFN-gamma-treated B16-F10 cells and also on eight additional mouse tumors and seven human melanoma cell lines. Primed 2C/RAG2(-/-)/PD-1(-/-) T cells showed augmented cytokine production, proliferation, and cytolytic activity against tumor cells compared with wild-type 2C cells. This effect was reproduced with anti-PD-L1 antibody present during the effector phase but not during the priming culture. Adoptive transfer of 2C/RAG2(-/-)/PD-1(-/-) T cells in vivo caused tumor rejection under conditions in which wild-type 2C cells or CTLA-4-deficient 2C cells did not reject. Our results support interfering with PD-L1/PD-1 interactions to augment the effector function of tumor antigen-specific CD8(+) T cells in the tumor microenvironment.

PURPOSE: Increased hepatocyte growth factor/MET signaling is associated with poor prognosis and acquired resistance to epidermal growth factor receptor (EGFR) -targeted drugs in patients with non-small-cell lung cancer (NSCLC). We investigated whether dual inhibition of MET/EGFR results in clinical benefit in patients with NSCLC. PATIENTS AND METHODS: Patients with recurrent NSCLC were randomly assigned at a ratio of one to one to receive onartuzumab plus erlotinib or placebo plus erlotinib; crossover was allowed at progression. Tumor tissue was required to assess MET status by immunohistochemistry (IHC). Coprimary end points were progression-free survival (PFS) in the intent-to-treat (ITT) and MET-positive (MET IHC diagnostic positive) populations; additional end points included overall survival (OS), objective response rate, and safety. RESULTS: There was no improvement in PFS or OS in the ITT population (n = 137; PFS hazard ratio [HR], 1.09; P = .69; OS HR, 0.80; P = .34). MET-positive patients (n = 66) treated with erlotinib plus onartuzumab showed improvement in both PFS (HR, .53; P = .04) and OS (HR, .37; P = .002). Conversely, clinical outcomes were worse in MET-negative patients treated with onartuzumab plus erlotinib (n = 62; PFS HR, 1.82; P = .05; OS HR, 1.78; P = .16). MET-positive control patients had worse outcomes versus MET-negative control patients (n = 62; PFS HR, 1.71; P = .06; OS HR, 2.61; P = .004). Incidence of peripheral edema was increased in onartuzumab-treated patients. CONCLUSION: Onartuzumab plus erlotinib was associated with improved PFS and OS in the MET-positive population. These results combined with the worse outcomes observed in MET-negative patients treated with onartuzumab highlight the importance of diagnostic testing in drug development.

7505 Background: Met is associated with a poor outcome in many cancers, including NSCLC. Met activation is a mechanism of resistance to EGFR inhibition, supporting dual inhibition of Met/EGFR. MetMAb is a monovalent monoclonal antibody that specifically binds the Met receptor. Methods: OAM4558g is a global randomized, double-blind phase II study comparing MetMAb plus erlotinib (ME) to placebo plus erlotinib (PE) in 2nd/3rd line NSCLC. Tissue collection was mandatory to assess c-Met IHC expression levels (Met Dx). Co-primary endpoints were PFS in the Met Dx+ and ITT populations. Safety and OS were additional endpoints. Following the initial unblinding, Met Dx- patients (pts) were removed from ME. Results: 128 NSCLC pts were equally randomized to receive ME or PE. 95% of tissue was evaluable for c-Met IHC, 88% for EGFR and KRAS mutations (mut), and 75% for MET FISH. Baseline characteristics were well balanced. 54% of pts had Met Dx+ NSCLC, which was associated with a worse outcome (OS HR 2.52, PE cohort). A total of 99 PFS and 70 OS events have occurred, median follow up is 9.9mos. In the Met Dx+ group, ME resulted in a statistically and clinically significant improvement in both PFS and OS. An OS benefit from ME was observed in MET FISH+ NSCLC as well as in FISH-/IHC+; removing pts with EGFR mut did not alter results. Selective benefit of ME was not observed in other subgroups. E-related toxicities were comparable between treatment arms. Conclusions: Met Dx+ NSCLC represented more than half the population and was associated with a worse outcome. The addition of M to E in these pts significantly improved PFS and OS, resulting in a near 3-fold reduction in the risk of death. This benefit was not exclusive to EGFR mut or MET FISH+ and was observed in FISH-/IHC+ pts suggesting IHC is a more sensitive predictor of benefit from MetMAb. Median (mo) Population N PFS HR OS HR PE ME 95% CI P c-Met IHC+ 65 0.47 1.5 3.0 0.26–0.85 0.01 0.37 4.6 12.6 0.20–0.71 0.002 MET FISH+ (≥5 copies) 19 0.47 2.4 12.6 0.15–1.49 0.19 FISH-/IHC+ 37 0.44 3.6 7.1 0.17–1.15 0.09 FISH-/IHC+/EGFR wt 32 0.59 3.6 7.1 0.22–1.59 0.29 c-Met IHC-* 56 3.02 9.2 5.5 1.13–8.11 0.021 ITT* 128 1.09 8.2 7.1 0.62–1.91 0.76 * Initial data cut.