Assessing Tumor-infiltrating Lymphocytes in Solid Tumors: A Practical Review for Pathologists and Proposal for a Standardized Method From the International Immunooncology Biomarkers Working Group: Part 1: Assessing the Host Immune Response, TILs in Invasive Breast Carcinoma and Ductal Carcinoma In Situ, Metastatic Tumor Deposits and Areas for Further Research

Assessment of tumor-infiltrating lymphocytes (TILs) in histopathologic specimens can provide important prognostic information in diverse solid tumor types, and may also be of value in predicting response to treatments. However, implementation as a routine clinical biomarker has not yet been achieved. As successful use of immune checkpoint inhibitors and other forms of immunotherapy become a clinical reality, the need for widely applicable, accessible, and reliable immunooncology biomarkers is clear. In part 1 of this review we briefly discuss the host immune response to tumors and different approaches to TIL assessment. We propose a standardized methodology to assess TILs in solid tumors on hematoxylin and eosin sections, in both primary and metastatic settings, based on the International Immuno-Oncology Biomarker Working Group guidelines for TIL assessment in invasive breast carcinoma. A review of the literature regarding the value of TIL assessment in different solid tumor types follows in part 2. The method we propose is reproducible, affordable, easily applied, and has demonstrated prognostic and predictive significance in invasive breast carcinoma. This standardized methodology may be used as a reference against which other methods are compared, and should be evaluated for clinical validity and utility. Standardization of TIL assessment will help to improve consistency and reproducibility in this field, enrich both the quality and quantity of comparable evidence, and help to thoroughly evaluate the utility of TILs assessment in this era of immunotherapy.

Multiplexed ion beam imaging analysis for quantitation of protein expression in cancer tissue sections

Part of developing therapeutics is the need to identify patients who will respond to treatment. For HER2-targeted therapies, such as trastuzumab, the expression level of HER2 is used to identify patients likely to receive benefit from therapy. Currently, chromogenic immunohistochemistry on patient tumor tissue is one of the methodologies used to assess the expression level of HER2 to determine eligibility for trastuzumab. However, chromogenic staining is fraught with serious drawbacks that influence scoring, which is additionally flawed due to the subjective nature of human/pathologist bias. Thus, to advance drug development and precision medicine, there is a need to develop technologies that are more objective and quantitative through the collection and integration of larger data sets. In proof of concept experiments, we show multiplexed ion beam imaging (MIBI), a novel imaging technology, can quantitate HER2 expression on breast carcinoma tissue with known HER2 status and those values correlate with pathologist-determined IHC scores. The same type of quantitative analysis using the mean pixel value of five individual cells and total pixel count of the entire image was extended to a blinded study of breast carcinoma samples of unknown HER2 scores. Here, a strong correlation between quantitation of HER2 by MIBI analysis and pathologist-derived HER2 IHC score was identified. In addition, a comparison between MIBI analysis and immunofluorescence-based automated quantitative analysis (AQUA) technology, an industry-accepted quantitation system, showed strong correlation in the same blind study. Further comparison of the two systems determined MIBI was comparable to AQUA analysis when evaluated against pathologist-determined scores. Using HER2 as a model, these data show MIBI analysis can quantitate protein expression with greater sensitivity and objectivity compared to standard pathologist interpretation, demonstrating its potential as a technology capable of advancing cancer and patient diagnostics.

Abstract 2708: A custom gene expression panel for consensus molecular subtype classification of archival primary and metastatic colorectal cancers

Stratification of Colorectal Cancer (CRC) into actionable molecular subtypes has tremendous clinical value. Recently, a consolidated classifier identified four molecularly distinct CRC subtypes (CMS1-4) that were associated with unique biology and clinical outcomes based on global transcriptional analysis of frozen tissues. Here, we developed and applied a novel CRC panel that is ideally suited for transcriptional classification of archival clinical samples. Findings from in silico analysis demonstrated that the 800 genes on our panel could accurately classify CRC samples from external public datasets into the correct CMS subtypes. We applied our panel in the analysis of a novel cohort of 312 formalin-fixed paraffin-embedded (FFPE) tissues from 205 patients, and were able to detect all 4 CMS subtypes in primary CRCs and in metastases. When we examined the CMS subtypes of primary tumors and matched metastases from 50 patients we found 70% of cases to be concordant, as were key biologies, such as WNT/MYC pathway activation in CMS2 and EMT features in tumors of the CMS4 subtypes. This was confirmed by in situ hybridization (ISH) using the markers ASCL2 for CMS2 and SPARC for CMS4, respectively. Discordance in the CMS subtypes between primary tumors and matched metastases were observed in 30% of cases and may reflect tumor heterogeneity. Our findings suggest that our CRC-focused panel many have clinical utility for CMS classification of FFPE samples, and point to potential risks of using CMS subtypes of primary tumors to inform clinical decision-making at the metastatic stage in a subset of patients.

Citation Format: Ling-Yuh Huw, Robert Piskol, Felipe de Sosa e Melo, Doris Kim, Xueping Qu, Hartmut Koeppen, Mark Lackner, Garret Hampton, Omar Kabbarah, Rachel Tam. A custom gene expression panel for consensus molecular subtype classification of archival primary and metastatic colorectal cancers [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 2708. doi:10.1158/1538-7445.AM2017-2708

Abstract 2790: PRC2 mediated repression of SMARCA2 predicts for EZH2 inhibitor activity in tumors with SWI/SNF mutations

A synthetic lethality caused by EZH2 inhibition in the context of SNF5 mutations is supported by both preclinical and recent clinical data, however the extent of the synthetic lethal relationship in the context of other SWI/SNF subunit mutations is not well understood. We determined that a subset of SMARCA4 mutant cancer models are sensitive to EZH2 inhibition. EZH2 inhibition resulted in a heterogenous phenotypic response characterized by senescence and/or apoptosis amongst models, and further lead to tumor growth inhibition in vivo. The differential sensitivity to EZH2 inhibition was not caused by a differential pharmacodynamic effect of the drug, nor differences in basal histone methylation or PRC2 subunit levels. However, expression of the SWI/SNF subunit, SMARCA2, delineated sensitivity amongst SMARCA4 mutant models tested. Expression of SMARCA2 further delineated sensitivity amongst other SWI/SNF mutant models tested, including SNF5 and ARID1A mutants. We determined that SMARCA2 is under PRC2 mediated suppression and the derepression of SMARCA2 was necessary for apoptosis, but not senescence, in response to EZH2 inhibition. SMARCA2 has been shown to be concurrently lost in a high percentage of SNF5 mutant malignant rhabdoid tumors and SMARCA4 mutant SCCOHT tumors, however we determined that ≈15% of SMARCA4 mutant NSCLCs concurrently lose SMARCA2. Our data supports monitoring SMARCA2 expression as a predictive biomarker for EZH2-targeted therapies that are currently being developed in the context of SWI/SNF mutant cancers.

Citation Format: Thomas Januario, Xiaofen Ye, Russell Bainer, Bruno Alicke, Margaret Solon, Benjamin Haley, Zora Modrusan, Stephen Gould, Hartmut Koeppen, Robert L. Yauch. PRC2 mediated repression of SMARCA2 predicts for EZH2 inhibitor activity in tumors with SWI/SNF mutations [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 2790. doi:10.1158/1538-7445.AM2017-2790

A Phase II Randomized Trial (GO27827) of First-Line FOLFOX Plus Bevacizumab with or Without the MET Inhibitor Onartuzumab in Patients with Metastatic Colorectal Cancer

BACKGROUND

Dysregulated hepatocyte growth factor/mesenchymal-epithelial transition (MET) signaling is associated with poor prognosis and resistance to vascular endothelial growth factor inhibition in metastatic colorectal cancer (mCRC). We report outcomes from a double-blind, multicenter phase II trial of the MET inhibitor onartuzumab in combination with mFOLFOX-6 and bevacizumab for mCRC (GO27827; NCT01418222).

MATERIALS AND METHODS

Patients were randomized 1:1 to receive onartuzumab (10 mg/kg intravenously [IV]) or placebo plus mFOLFOX-6 and bevacizumab (5 mg/kg IV). Oxaliplatin was given for 8-12 cycles; other agents were continued until disease progression, unacceptable toxicity, or death. The primary endpoint was progression-free survival (PFS) in the intent-to-treat (ITT) and MET immunohistochemistry (IHC) expression-positive populations.

RESULTS

Between September 2011 and November 2012, 194 patients were enrolled. In September 2013, an interim analysis recommended stopping onartuzumab treatment due to lack of efficacy. At the time of the final analysis in February 2014, no significant improvement in PFS was seen with onartuzumab versus placebo in either the ITT or MET IHC-positive populations. An improvement in PFS was noted in the MET IHC-negative population. Neither overall survival nor response rate was improved with onartuzumab. The incidence of fatigue, peripheral edema, and deep vein thrombosis was increased with onartuzumab relative to placebo.

CONCLUSION

Onartuzumab combined with mFOLFOX-6 and bevacizumab did not significantly improve efficacy outcomes in either the ITT or MET IHC-positive populations. MET expression by IHC was not a predictive biomarker in this setting. The Oncologist 2017;22:264-271 IMPLICATIONS FOR PRACTICE: The addition of onartuzumab to mFOLFOX-6 plus bevacizumab did not improve outcomes in patients with previously untreated metastatic colorectal cancer in this randomized, phase II study. Although initial results with onartuzumab were promising, a number of phase II/III clinical trials have reported a lack of improvement in efficacy with onartuzumab combined with standard-of-care therapies in several tumor types. Furthermore, negative study data have been published for rilotumumab and ficlatuzumab, both of which block hepatocyte growth factor binding to the mesenchymal-epithelial transition (MET) receptor. MET immunohistochemistry was not a predictive biomarker. It remains to be seen if other biomarkers or small molecule inhibitors may be more appropriate for inhibiting this oncogenic pathway.

Tumour and host cell PD-L1 is required to mediate suppression of anti-tumour immunity in mice

Expression of PD-L1, the ligand for T-cell inhibitory receptor PD-1, is one key immunosuppressive mechanism by which cancer avoids eradication by the immune system. Therapeutic use of blocking antibodies to PD-L1 or its receptor PD-1 has produced unparalleled, durable clinical responses, with highest likelihood of response seen in patients whose tumour or immune cells express PD-L1 before therapy. The significance of PD-L1 expression in each cell type has emerged as a central and controversial unknown in the clinical development of immunotherapeutics. Using genetic deletion in preclinical mouse models, here we show that PD-L1 from disparate cellular sources, including tumour cells, myeloid or other immune cells can similarly modulate the degree of cytotoxic T-cell function and activity in the tumour microenvironment. PD-L1 expression in both the host and tumour compartment contribute to immune suppression in a non-redundant fashion, suggesting that both sources could be predictive of sensitivity to therapeutic agents targeting the PD-L1/PD-1 axis.

Randomized, Double-Blind, Placebo-Controlled, Multicenter Phase II Study of Onartuzumab Plus Bevacizumab Versus Placebo Plus Bevacizumab in Patients With Recurrent Glioblastoma: Efficacy, Safety, and Hepatocyte Growth Factor and O6-Methylguanine–DNA Methyltransferase Biomarker Analyses

Purpose

Bevacizumab regimens are approved for the treatment of recurrent glioblastoma in many countries. Aberrant mesenchymal-epithelial transition factor (MET) expression has been reported in glioblastoma and may contribute to bevacizumab resistance. The phase II study GO27819 investigated the monovalent MET inhibitor onartuzumab plus bevacizumab (Ona + Bev) versus placebo plus bevacizumab (Pla + Bev) in recurrent glioblastoma.

Methods

At first recurrence after chemoradiation, bevacizumab-naïve patients with glioblastoma were randomly assigned 1:1 to receive Ona (15 mg/kg, once every 3 weeks) + Bev (15 mg/kg, once every 3 weeks) or Pla + Bev until disease progression. The primary end point was progression-free survival by response assessment in neuro-oncology criteria. Secondary end points were overall survival, objective response rate, duration of response, and safety. Exploratory biomarker analyses correlated efficacy with expression levels of MET ligand hepatocyte growth factor, O6-methylguanine–DNA methyltransferase promoter methylation, and glioblastoma subtype.

Results

Among 129 patients enrolled (Ona + Bev, n = 64; Pla + Bev, n = 65), baseline characteristics were balanced. The median progression-free survival was 3.9 months for Ona + Bev versus 2.9 months for Pla + Bev (hazard ratio, 1.06; 95% CI, 0.72 to 1.56; P = .7444). The median overall survival was 8.8 months for Ona + Bev and 12.6 months for Pla + Bev (hazard ratio, 1.45; 95% CI, 0.88 to 2.37; P = .1389). Grade ≥ 3 adverse events were reported in 38.5% of patients who received Ona + Bev and 35.9% of patients who received Pla + Bev. Exploratory biomarker analyses suggested that patients with high expression of hepatocyte growth factor or unmethylated O6-methylguanine–DNA methyltransferase may benefit from Ona + Bev.

Conclusion

There was no evidence of further clinical benefit with the addition of onartuzumab to bevacizumab compared with bevacizumab plus placebo in unselected patients with recurrent glioblastoma in this phase II study; however, further investigation into biomarker subgroups is warranted.

Brain Distribution and Efficacy of the Brain Penetrant PI3K Inhibitor GDC-0084 in Orthotopic Mouse Models of Human Glioblastoma

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults. Limited treatment options have only marginally impacted patient survival over the past decades. The phophatidylinositol 3-kinase (PI3K) pathway, frequently altered in GBM, represents a potential target for the treatment of this glioma. 5-(6,6-Dimethyl-4-morpholino-8,9-dihydro-6H-[1,4]oxazino[4,3-e]purin-2-yl)pyrimidin-2-amine (GDC-0084) is a PI3K inhibitor that was specifically optimized to cross the blood-brain barrier. The goals of our studies were to characterize the brain distribution, pharmacodynamic (PD) effect, and efficacy of GDC-0084 in orthotopic xenograft models of GBM. GDC-0084 was tested in vitro to assess its sensitivity to the efflux transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) and in vivo in mice to evaluate its effects on the PI3K pathway in intact brain. Mice bearing U87 or GS2 intracranial tumors were treated with GDC-0084 to assess its brain distribution by matrix-assisted laser desorption ionization (MALDI) imaging and measure its PD effects and efficacy in GBM orthotopic models. Studies in transfected cells indicated that GDC-0084 was not a substrate of P-gp or BCRP. GDC-0084 markedly inhibited the PI3K pathway in mouse brain, causing up to 90% suppression of the pAkt signal. MALDI imaging showed GDC-0084 distributed evenly in brain and intracranial U87 and GS2 tumors. GDC-0084 achieved significant tumor growth inhibition of 70% and 40% against the U87 and GS2 orthotopic models, respectively. GDC-0084 distribution throughout the brain and intracranial tumors led to potent inhibition of the PI3K pathway. Its efficacy in orthotopic models of GBM suggests that it could be effective in the treatment of GBM. GDC-0084 is currently in phase I clinical trials.

A multicenter, single-arm, open-label, phase 2 study of apitolisib (GDC-0980) for the treatment of recurrent or persistent endometrial carcinoma (MAGGIE study)

BACKGROUND

The current single-arm, open-label trial was designed to evaluate the activity of apitolisib (GDC-0980), a dual phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) inhibitor, in patients with advanced endometrial cancer (EC).

METHODS

Patients with recurrent or persistent EC who were treated with 1 to 2 prior lines of chemotherapy but no prior PI3K/mTOR inhibitor received oral apitolisib at a dose of 40 mg daily during 28-day cycles until disease progression or intolerable toxicity occurred. Patients with type I/II diabetes who required insulin were excluded. The primary endpoints were progression-free survival (PFS) at 6 months and objective response rate.

RESULTS

A total of 56 women were enrolled, including 13 (23%) with well-controlled diabetes. Reasons for discontinuation were disease progression (24 patients; 43%), adverse events (13 patients; 23%), and withdrawal by subject (12 patients; 21%). Grade 3/4 apitolisib-related adverse events were hyperglycemia (46%), rash (30%), colitis (5%), and pneumonitis (4%) (toxicities were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.0]). The PFS rate at 6 months was 20% (Kaplan-Meier estimate; 95% confidence interval [95% CI], 7%-33%). The objective response rate was 6% (confirmed). The median PFS was 3.5 months (95% CI, 2.7-3.7 months) and the median overall survival was 15.7 months (95% CI, 9.2-17.0 months). Nineteen patients discontinued the study before the first tumor assessment. Dose reductions were required for 4 diabetic (31%) and 18 nondiabetic (42%) patients. Comprehensive molecular profiling of 46 evaluable archival tumor samples demonstrated that 57% of patients had at least 1 alteration in phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), phosphatase and tensin homolog (PTEN), or AKT1. All 3 patients with a confirmed response had at least 1 alteration in a PI3K pathway gene.

CONCLUSIONS

The antitumor activity noted with the use of a dose of 40 mg of apitolisib daily was limited by tolerability, especially in diabetic patients. Patients with PI3K pathway mutations may have derived enhanced benefit from apitolisib. Cancer 2016;122:3519-28. © 2016 American Cancer Society.

Atezolizumab in combination with bevacizumab enhances antigen-specific T-cell migration in metastatic renal cell carcinoma

Anti-tumour immune activation by checkpoint inhibitors leads to durable responses in a variety of cancers, but combination approaches are required to extend this benefit beyond a subset of patients. In preclinical models tumour-derived VEGF limits immune cell activity while anti-VEGF augments intra-tumoral T-cell infiltration, potentially through vascular normalization and endothelial cell activation. This study investigates how VEGF blockade with bevacizumab could potentiate PD-L1 checkpoint inhibition with atezolizumab in mRCC. Tissue collections are before treatment, after bevacizumab and after the addition of atezolizumab. We discover that intra-tumoral CD8⁺ T cells increase following combination treatment. A related increase is found in intra-tumoral MHC-I, Th1 and T-effector markers, and chemokines, most notably CX3CL1 (fractalkine). We also discover that the fractalkine receptor increases on peripheral CD8⁺ T cells with treatment. Furthermore, trafficking lymphocyte increases are observed in tumors following bevacizumab and combination treatment. These data suggest that the anti-VEGF and anti-PD-L1 combination improves antigen-specific T-cell migration.

Cancer immunotherapy can be used in combination with other therapies for a better response. Here, the authors conduct a phase Ib clinical study and report the clinical activity and the immune response of the anti-PDL1 agent, atezolizumab, in combination with bevacizumab in ten patients with metastatic renal cell carcinoma.

Abstract 1837: Comprehensive RNA-seq transcriptome interrogation of paired hepatocellular carcinoma and cirrhosis tissues revealed significant molecular features of disease evolution and modulation of tumor immunity

First 2 authors contributed equally

Hepatocellular carcinoma (HCC) is the second most common cause of death from cancer worldwide with extremely poor prognosis. HCC is known to be closely associated with liver injury-induced cirrhosis caused by various etiologies, including HBV infection. The prolonged timeline and heterogeneous nature of HCC adds complexity to dissecting the biology of this disease in humans. While Sorafenib is approved for the first-line treatment of metastatic HCC, most patients rapidly progress on treatment with Sorafenib. Consequently, alternative therapeutic options for HCC are much needed. The identification of molecular subtypes and reliable biomarkers associated with disease evolution is critical in facilitating development of new therapeutic agents in HCC.

To understand the manifestation of early molecular events in HCC disease progression in human, we analyzed genome-wide RNA-seq data derived from 100 paired samples consisting of HCC tumors (most with 60-80% tumor content) and adjacent cirrhotic tissues from early stage patients (TNM system: T1N0M0, T2N0M0, and T3N0M0; similar to BCLC stage A and B). Differential expression analysis revealed a cluster of genes that significantly differentiated HCC from cirrhotic tissues and illustrated a widespread deregulation of cell cycle machinery modulated by probable molecular abnormalities represented by Polo-Like Kinase, Checkpoint kinases, G2/M DNA damage checkpoint regulation, DNA damage-induced 14-3-3σ signaling, ATM signaling, and estrogen-mediated S-phase entry. Prominent down-regulation of FXR/LXR/RXR activation was also observed in HCC tumors. Strikingly, the unsupervised hierarchical clustering of both cirrhotic and HCC tissues revealed 3 groups of genes with mRNA expression closely correlating with disease progression stage-wise from cirrhosis to T1, T2, and T3 stages. Specifically, we made a novel observation illustrating the stage-wise activation of Wnt signaling pathway, but de-activation of MAPK pathway. Upon in-depth analysis, our data also suggests that as HCC progresses, translation machinery and embryonic morphogenesis are stimulated, while angiogenesis, negative regulation of apoptosis, and mesenchymal cell differentiation are possibly impinged. In addition, we found that components of processes crucial for activating immune response appear to be impaired as disease progresses from cirrhosis to stage T3. To confirm the aforementioned finding through focused assessment of immune-microenvironment by gene expression, we utilized Fluidigm platform and corroborated the down-regulation of effector T cell signature.

In conclusion, data presented provides a holistic depiction of evolution of HCC and the associated tumor immunity, thus paving a way for future detailed subtyping and therapeutics discovery.

Citation Format: Bonnie P. Liu, Kwame Okrah, Jeff Cheng, Maipelo Motlhabi, Charlie Sun, Teiko Sumiyoshi, Shoji Ikeda, Hartmut Koeppen, Zineb Mounir, Craig Cummings, Nadia Haque, Garret Hampton, Lukas Amler, Mark Lackner, Shih-Min A. Huang. Comprehensive RNA-seq transcriptome interrogation of paired hepatocellular carcinoma and cirrhosis tissues revealed significant molecular features of disease evolution and modulation of tumor immunity. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1837.

Preclinical pharmacokinetics, pharmacodynamics, tissue distribution, and tumor penetration of anti-PD-L1 monoclonal antibody, an immune checkpoint inhibitor

MPDL3280A is a human monoclonal antibody that targets programmed cell death-1 ligand 1 (PD-L1), and exerts anti-tumor activity mainly by blocking PD-L1 interaction with programmed cell death-1 (PD-1) and B7.1. It is being investigated as a potential therapy for locally advanced or metastatic malignancies. The purpose of the study reported here was to characterize the pharmacokinetics, pharmacodynamics, tissue distribution and tumor penetration of MPDL3280A and/or a chimeric anti-PD-L1 antibody PRO304397 to help further clinical development. The pharmacokinetics of MPDL3280A in monkeys at 0.5, 5 and 20 mg · kg(-1) and the pharmacokinetics / pharmacodynamics of PRO304397 in mice at 1, 3 10 mg · kg(-1) were determined after a single intravenous dose. Tissue distribution and tumor penetration for radiolabeled PRO304397 in tumor-bearing mouse models were determined. The pharmacokinetics of MPDL3280A and PRO304397 were nonlinear in monkeys and mice, respectively. Complete saturation of PD-L1 in blood in mice was achieved at serum concentrations of PRO304397 above ∼ 0.5 µg · mL(-1). Tissue distribution and tumor penetration studies of PRO304397 in tumor-bearing mice indicated that the minimum tumor interstitial to plasma radioactivity ratio was ∼ 0.3; saturation of target-mediated uptake in non-tumor tissues and desirable exposure in tumors were achieved at higher serum concentrations, and the distribution into tumors was dose-and time-dependent. The biodistribution data indicated that the efficacious dose is mostly likely higher than that estimated based on simple pharmacokinetics/pharmacodynamics in blood. These data also allowed for estimation of the target clinical dose for further development of MPDL3280A.

Phase I Study of Apitolisib (GDC-0980), Dual Phosphatidylinositol-3-Kinase and Mammalian Target of Rapamycin Kinase Inhibitor, in Patients with Advanced Solid Tumors

PURPOSE

This first-in-human phase I trial assessed the safety, tolerability, and preliminary antitumor activity of apitolisib (GDC-0980), a dual inhibitor of class I PI3K, and mTOR kinases.

EXPERIMENTAL DESIGN

Once-daily oral apitolisib was administered to patients with solid tumors for days 1 to 21 or 1 to 28 of 28-day cycles. Pharmacokinetic and pharmacodynamic parameters were assessed.

RESULTS

Overall, 120 patients were treated at doses between 2 and 70 mg. The commonest ≥G3 toxicities related to apitolisib at the recommended phase 2 dose (RP2D) at 40 mg once daily included hyperglycemia (18%), rash (14%), liver dysfunction (12%), diarrhea (10%), pneumonitis (8%), mucosal inflammation (6%), and fatigue (4%). Dose-limiting toxicities (1 patient each) were G4 fasting hyperglycemia at 40 mg (21/28 schedule) and G3 maculopapular rash and G3 fasting hyperglycemia at 70 mg (21/28 schedule). The pharmacokinetic profile was dose-proportional. Phosphorylated serine-473 AKT levels were suppressed by ≥90% in platelet-rich plasma within 4 hours at the MTD (50 mg). Pharmacodynamic decreases in fluorodeoxyglucose positron emission tomography uptake of >25% occurred in 66% (21/32) of patients dosed at 40 mg once daily. Evidence of single-agent activity included 10 RECIST partial responses (PR; confirmed for peritoneal mesothelioma, PIK3CA mutant head-and-neck cancer, and three pleural mesotheliomas).

CONCLUSIONS

Apitolisib exhibited dose-proportional pharmacokinetics with target modulation at doses ≥16 mg. The RP2D was 40 mg once-daily 28/28 schedule; severe on-target toxicities were apparent at ≥40 mg, particularly pneumonitis. Apitolisib was reasonably tolerated at 30 mg, the selected dose for pleural mesothelioma patients given limited respiratory reserve. Modest but durable antitumor activity was demonstrated. Clin Cancer Res; 22(12); 2874-84. ©2016 AACR.

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 <1% overlap, each benefiting from atezo. In POPLAR, ORR in TC3 and IC3 subgroups was 40% and 30%, respectively, vs 14.6% in all pts treated with atezo. IC3 tumors had a high frequency of immune infiltrates, including CD8+ T cells, localized in the intra-epithelium, epithelial/stroma interface and stroma. These tumors also exhibited high expression of genes associated with effector T cells, consistent with PD-L1 regulated by an adaptive IFNγ-driven mechanism. However, high infiltration of CD8+ T cells within the tumor at baseline was not associated with response to atezo (P=.39), suggesting that the mechanism of response is not exclusively due to adaptive antitumor T-cell immunity. In contrast, TC3 tumors had distinct histopathologic characteristics, with a dense desmoplastic and sclerotic TME and low intratumoral CD8 infiltrate. PD-L1 on TC appeared to be regulated by intrinsic tumor mechanisms, including promoter methylation. TC0 and IC0 tumors (lowest/no PD-L1 expression; ≈30% of NSCLC) showed little/no evidence of immune infiltration or activation, consistent with immunologic ignorance.

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.

Randomized, phase II, placebo-controlled trial of onartuzumab and/or bevacizumab in combination with weekly paclitaxel in patients with metastatic triple-negative breast cancer

BACKGROUND

Increased hepatocyte growth factor/MET signaling is associated with an aggressive phenotype and poor prognosis in triple-negative breast cancer (TNBC). We evaluated the benefit of adding onartuzumab, a monoclonal anti-MET antibody, to paclitaxel with/without bevacizumab in patients with TNBC.

PATIENTS AND METHODS

Women with metastatic TNBC were randomized to receive onartuzumab plus placebo plus weekly paclitaxel (OP; n = 60) or onartuzumab plus bevacizumab plus paclitaxel (OBP; n = 63) or placebo plus bevacizumab plus paclitaxel (BP; n = 62). The primary end point was progression-free survival (PFS); additional end points included overall survival (OS), objective response rate (ORR), and safety. This trial was hypothesis generating and did not have power to detect minimum clinically meaningful differences between treatment arms.

RESULTS

There was no improvement in PFS with the addition of onartuzumab to BP [hazard ratio (HR), 1.08; 95% confidence interval (CI) 0.69-1.70]; the risk of a PFS event was higher with OP than with BP (HR, 1.74; 95% CI 1.13-2.68). Most patients had MET-negative tumors (88%); PAM50 subtype analysis showed basal-like tumors in 68% of samples. ORR was higher in the bevacizumab arms (OBP: 42.2%; 95% CI 28.6-57.1; BP: 54.7%; 95% CI 41.0-68.4) compared with OP (27.5%; 95% CI 15.9-40.6). Median OS was shorter with OBP (HR, 1.36; 95% CI 0.75-2.46) and OP (HR, 1.92; 95% CI 1.03-3.59), than with BP. Peripheral edema was more frequent in the onartuzumab arms (OBP, 51.8%; OP, 58.6%) versus BP (17.7%).

CONCLUSION

This study did not show a clinical benefit of the addition of onartuzumab to paclitaxel with/without bevacizumab in patients with predominantly MET-negative TNBC.

CLINICALTRIALSGOV

NCT01186991.

Abstract PR03: CD8+ T-cell distribution and immunomodulator expression in BRAF-mutant melanoma affect the response to BRAF inhibitor and chemotherapy

Although intense effort has been made in studying immune cell dynamics in tumors after treatment with targeted therapies and to recharacterize tumor stages based on their immune cell components, less is known about how baseline immune cell characteristics in tumors affect response to approved therapies. Here we describe baseline expression of immune regulators and CD8+ T-cell distribution in BRAF-mutated metastatic melanoma and their relationship with progression-free survival (PFS) on vemurafenib and chemotherapy. To our knowledge, we are the first to describe the baseline characteristics of tumor-infiltrating lymphocytes and their impact on outcomes in a large randomized, controlled trial in melanoma.

Archival or baseline samples were collected from patients in 2 clinical trials (BRIM2 and BRIM3) and analyzed. A total of 252 RNA samples were prepared from formalin-fixed, paraffin-embedded (FFPE) tissue samples and profiled for expression using a panel of 96 immune genes on the Fluidigm platform (Fluidigm Corp). Additionally, for 277 patients from the BRIM3 trial, CD8+ T cells were detected by immunohistochemistry (IHC) and quantified using Definiens (Definiens AG). Patients were defined as high or low expressers based on a median cutoff, and hazard ratios (HRs) were determined by cox proportional hazards modeling of PFS. HRs refer to the comparison of high and low expressing groups, where an HR<1 is indicative of a better outcome for the high-expressing group.

A discovery (BRIM2) – validation (BRIM3) scheme was applied to assess the prognostic value of the expression of immune-related genes. Samples from the BRIM3 dacarbazine and vemurafenib arms were compared to assess the predictive value of the markers on the treatment effect of vemurafenib. Of the genes tested, 26 met our discovery criteria in the BRIM2 trial and 2, IL7 and IL12A, were validated in BRIM3. In the vemurafenib arm of BRIM3, patients with high expression of IL7 had improved PFS compared with patients with low IL7, with an HR of 0.63 (95% confidence interval [CI]: 0.41-0.97; P=0.03); high expression of IL12A had an HR of 0.58 (0.38-0.88; P=0.01). Neither gene was associated with PFS in the dacarbazine-treated arm; however, high and low expressers of both genes benefited from vemurafenib treatment.

Because immune contexture is known to be associated with outcomes, slides were stained for CD8+ T-cell content in 3 marker areas: center, peripheral, and invasive margin. In the dacarbazine arm, increased PFS was seen in patients with higher CD8+ T-cell content in the tumor center or periphery, with HRs of 0.58 (0.43-0.94; P=0.02) and 0.39 (0.25-0.59; P<0.01), respectively. CD8+ T-cell content did not show a significant effect in vemurafenib-treated patients, and all groups benefited from vemurafenib treatment.

Based on these characterizations, tumor immune cell components seem to play important but varying roles in response to dacarbazine or vemurafenib treatment in BRAF-mutant melanoma.

This abstract is also being presented as Poster B22.

Citation Format: Matthew Wongchenko, Christina Rabe, Jeffrey Sosman, Grant McArthur, Yuanyuan Xiao, Houston Gilbert, Luc Andries, Mark Kockx, Hartmut Koeppen, Priti Hegde, Lukas Amler, Yibing Yan, Antoni Ribas. CD8+ T-cell distribution and immunomodulator expression in BRAF-mutant melanoma affect the response to BRAF inhibitor and chemotherapy. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Melanoma: From Biology to Therapy; Sep 20-23, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(14 Suppl):Abstract nr PR03.

Abstract B03: Pharmacodynamic biomarker evaluation in phase I clinical trials of selective PI3K and PI3K/mTOR inhibitors

Background: The PI3K/Akt pathway is frequently altered in cancer by multiple mechanisms including PI3K activating mutations, PTEN loss, RTK activation, and other oncogenic mutations. GDC-0941 and GDC-0980 are selective PI3K and dual PI3K/mTOR inhibitors, respectively, which are currently in clinical development. Pharmacodynamic changes in biomarkers in response to dose and exposures were analyzed from sequential biopsies from phase I studies of GDC-0941 and GDC-0980. The purpose was to evaluate pathway inhibition at tolerable doses, as well as look for associations between modulation of phosphorylation and gene expression of downstream PI3K factors and interactions with cancer immune cell infiltration.

Methods: Pre- and post-treatment biopsies were collected from a subset of patients who were treated with escalating doses of GDC-0941 (NCT00876122, NCT00876109) or GDC-0980 (NCT00854126). In addition to previously described phospho-S6, phospho-AKT, and phospho-PRAS40 analysis by immunohistochemistry (IHC), CyclinD1, phospho-ERK, Ki-67, and markers of T-cell infiltration (CD8, PD-L1) were also assessed by IHC. Gene expression analysis was also performed with the nCounter® Analysis System (NanoString Technologies) to determine if pathway modulation can be assessed more quantitatively across a broader set of markers, and to determine whether feedback upregulation of pathway components was observed in treated patient samples. Genes analyzed included PI3K pathway, apoptosis/cell cycle, and tumor immunity related genes.

Results: Pharmacodynamic biomarker assays were conducted on 23 paired samples from the GDC-0941 study and 22 paired samples from the GDC-0980 study. Post-dose samples were obtained within hours of anticipated Cmax of both drugs. Reduction of phospho-S6, phospho-AKT, and phospho-PRAS40 were observed in a dose and exposure dependent manner. Upregulation of immune-related proteins was not observed after two weeks dosing with GDC-0941 or GDC-0980, which could be impacted by inhibition of T-cell signaling through PI3K. We report here the pharmacodynamic gene expression analysis, as measured by the NanoString nCounter® system, in patients from whom tissue was available, and analysis of the extent to which these the pharmacodynamic biomarkers are associated with each other. Based on PK modeling and PD, the doses achieved in Phase I studies enable future studies to be conducted at doses associated with tumor xenograft shrinkage (J Clin Oncol 29: 2011 [suppl; abstr 3052, 3021], Mol Cancer Ther 2009;8[12 Suppl]:B137).

Conclusions: Pharmacodynamic assays confirmed effective broad pathway knockdown of multiple signaling components at safe and tolerated clinical doses of GDC-0941 and GDC-0980. What remains unclear is duration and magnitude of pathway inhibition required will translate to clinical efficacy and translatability across tumor types that may have different PI3K pathway dependencies and alterations. These data supports further clinical testing to evaluate efficacy in these different patient subsets.

Citation Format: Yoshito Nakanishi, Jill M. Spoerke, Mika Derynck, Jennifer O. Lauchle, Hartmut Koeppen, Jill Fredrickson, Joseph Ware, Garret Hampton, Yibing Yan, Mark R. Lackner. Pharmacodynamic biomarker evaluation in phase I clinical trials of selective PI3K and PI3K/mTOR inhibitors. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr B03.

Anti-CD22 and anti-CD79B antibody drug conjugates are active in different molecular diffuse large B-cell lymphoma subtypes

Antibody drug conjugates (ADCs), in which cytotoxic drugs are linked to antibodies targeting antigens on tumor cells, represent promising novel agents for the treatment of malignant lymphomas. Pinatuzumab vedotin is an anti-CD22 ADC and polatuzumab vedotin an anti-CD79B ADC that are both linked to the microtubule-disrupting agent monomethyl auristatin E (MMAE). In the present study, we analyzed the activity of these agents in different molecular subtypes of diffuse large B-cell lymphoma (DLBCL) both in vitro and in early clinical trials. Both anti-CD22-MMAE and anti-CD79B-MMAE were highly active and induced cell death in the vast majority of activated B-cell-like (ABC) and germinal center B-cell-like (GCB) DLBCL cell lines. Similarly, both agents induced cytotoxicity in models with and without mutations in the signaling molecule CD79B. In line with these observations, relapsed and refractory DLBCL patients of both subtypes responded to these agents. Importantly, a strong correlation between CD22 and CD79B expression in vitro and in vivo was not detectable, indicating that patients should not be excluded from anti-CD22-MMAE or anti-CD79B-MMAE treatment because of low target expression. In summary, these studies suggest that pinatuzumab vedotin and polatuzumab vedotin are active agents for the treatment of patients with different subtypes of DLBCL.

Abstract A03: Comprehensive predictive biomarker evaluation in two phase II clinical trials of the PI3K/mTOR inhibitor GDC-0980 in metastatic renal cell carcinoma and advanced endometrial cancer

Background: The PI3K/mTOR pathway is frequently activated in cancer by multiple mechanisms. GDC-0980 is a dual pan-PI3K and mTOR (TORC1/2) inhibitor that has been evaluated in two Phase II studies (J Clin Oncol 32:5s, 2014 [suppl; abstr 4525 and 5513]). The randomized ROVER study showed that the PI3K/mTOR inhibitor GDC-0980 did not improve efficacy over the TORC1 inhibitor everolimus in metastatic renal cell carcinoma (mRCC). The single arm MAGGIE study evaluated the activity of GDC-0080 in patients with advanced endometrial cancer (EC). Although some single agent anti-tumor activity was observed, overall evaluation of anti-tumor activity of GDC-0980 was limited by tolerability, especially in diabetic patients. Comprehensive biomarker analysis, including targeted next generation sequencing (NGS) and a panel of biomarkers tailored to each tumor type, was conducted in both Phase II studies to determine the prevalence of PI3K/mTOR pathway alterations, and to assess the association between anti-tumor activity and candidate predictive biomarkers.

Methods: The primary and secondary endpoints included progression-free survival (PFS) and objective response rate (ORR). Archival tissue samples were collected for biomarker analysis, and correlations with efficacy were retrospectively explored. Samples were subjected to targeted NGS (Illumina) covering 88 oncogenes and tumor suppressors, copy number analysis using quantitative-PCR, PTEN immunohistochemistry (IHC), HIF1A IHC (ROVER), and gene expression analysis (NanoString nCounter® System, ROVER).

Results: In ROVER, the median PFS was significantly shorter for GDC-0980 than everolimus. Retrospective biomarker analyses revealed a relationship between VHL mutation status (by NGS) and improved PFS with everolimus but not GDC-0980. High HIF1A protein expression was associated with longer PFS in both arms, whereas low expression of STK11/LKB1 mRNA was associated with benefit with everolimus only. Additional gene expression analysis of PI3K pathway, apoptosis/cell cycle, and tumor immunity related genes will be presented. In MAGGIE, PFS at 6 months was estimated to be 20%, and the ORR was 9% (unconfirmed). Evaluable archival tumor samples were obtained from 88% of the patients and 52% of patients had at least one alteration in PIK3CA, PTEN or AKT1. PTEN loss by IHC was generally well correlated with mutation status determined by NGS. All 5 patients with either a confirmed or investigator assessed partial response had at least one PI3K pathway alteration.

Conclusions: Clinical data to date have suggested that identification of predictive biomarkers for agents targeting PI3K/mTOR signaling is challenging and will require tailoring to specific tumor types. Here we provide comprehensive assessment from two phase II clinical studies of GDC-0980. Our data, although retrospective in nature and requiring confirmation, suggest that pathway activation along the VHL-HIF1A axis may be predictive of anti-tumor activity for mTOR-targeting agents in mRCC. Our results in EC suggest that at least in this study population, frequency of pathway alterations was somewhat lower than observed in prior published data, but the presence of PIK3CA or AKT1 mutations or PTEN loss enriched for anti-tumor activity. Clinical trial information: NCT01442090 (mRCC), NCT01455493 (EC).

Citation Format: Jill M. Spoerke, Vicky Makker, Carol Aghajanian, Powles Thomas, Robert J. Motzer, Jennifer O. Lauchle, Hema Parmar, Houston Gilbert, Wei Lin, Bridget O'Keeffe, Michelle Byrtek, Hartmut Koeppen, Yulei Wang, Shan Lu, Ling-Yuh Huw, Garret M. Hampton, Mark R. Lackner. Comprehensive predictive biomarker evaluation in two phase II clinical trials of the PI3K/mTOR inhibitor GDC-0980 in metastatic renal cell carcinoma and advanced endometrial cancer. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr A03.

Patients with Slowly Proliferative Early Breast Cancer Have Low Five-Year Recurrence Rates in a Phase III Adjuvant Trial of Capecitabine

PURPOSE

We conducted a randomized phase III study to determine whether patients with early breast cancer would benefit from the addition of capecitabine (X) to a standard regimen of doxorubicin (A) plus cyclophosphamide (C) followed by docetaxel (T).

EXPERIMENTAL DESIGN

Treatment comprised eight cycles of AC→T (T dose: 100 mg/m(2) on day 1) or AC→XT (X dose: 825 mg/m(2) twice daily, days 1-14; T dose: 75 mg/m(2) on day 1). The primary endpoint was 5-year disease-free survival (DFS).

RESULTS

Of 2,611 women, 1,304 were randomly assigned to receive AC→T and 1,307 to receive AC→XT. After a median follow-up of 5 years, the study failed to meet its primary endpoint [HR, 0.84; 95% confidence interval (CI), 0.67-1.05; P = 0.125]. A significant improvement in overall survival, a secondary endpoint, was seen with AC→XT versus AC→T (HR, 0.68; 95% CI, 0.51-0.92; P = 0.011). There were no unexpected adverse events. Of patients with estrogen receptor (ER)-positive/HER2-negative disease, 70% of whom were node-positive, 26% and 59% had tumors with a centrally assessed Ki-67 score of <10% or <20%, respectively, and only 17 (2%) and 53 (6%) DFS events, respectively, occurred in these groups at 7 years.

CONCLUSIONS

The very low event rate in patients with ER-positive, low Ki-67 cancers, regardless of nodal status, strongly suggests that these patients should not be enrolled in adjuvant trials that assess 5-year DFS rates and that central Ki-67 analyses can identify these patients.