Integrative Analyses of Tumor and Peripheral Biomarkers in the Treatment of Advanced Renal Cell Carcinoma

The phase III JAVELIN Renal 101 trial demonstrated prolonged progression-free survival (PFS) in patients (N = 886) with advanced renal cell carcinoma treated with first-line avelumab + axitinib (A+Ax) versus sunitinib. We report novel findings from integrated analyses of longitudinal blood samples and baseline tumor tissue. PFS was associated with elevated lymphocyte levels in the sunitinib arm and an abundance of innate immune subsets in the A+Ax arm. Treatment with A+Ax led to greater T-cell repertoire modulation and less change in T-cell numbers versus sunitinib. In the A+Ax arm, patients with tumors harboring mutations in ≥2 of 10 previously identified PFS-associated genes (double mutants) had distinct circulating and tumor-infiltrating immunologic profiles versus those with wild-type or single-mutant tumors, suggesting a role for non-T-cell-mediated and non-natural killer cell-mediated mechanisms in double-mutant tumors. We provide evidence for different immunomodulatory mechanisms based on treatment (A+Ax vs. sunitinib) and tumor molecular subtypes.

SIGNIFICANCE

Our findings provide novel insights into the different immunomodulatory mechanisms governing responses in patients treated with avelumab (PD-L1 inhibitor) + axitinib or sunitinib (both VEGF inhibitors), highlighting the contribution of tumor biology to the complexity of the roles and interactions of infiltrating immune cells in response to these treatment regimens. This article is featured in Selected Articles from This Issue, p. 384.

DELTA-1: A global, multicenter, phase 2 study of ITIL-168, an unrestricted autologous tumor-infiltrating lymphocyte (TIL) cell therapy, in adult patients with advanced cutaneous melanoma

TPS9594

Background: Patients (pts) with advanced (unresectable or metastatic) cutaneous melanoma and persistent disease after checkpoint inhibitor therapy have poor outcomes and limited treatment options, highlighting a significant unmet medical need (Schadendorf D et al. Lancet. 2018;392:971-984). Investigational autologous TIL cell therapies have shown promise in this population, partly attributable to their intrinsic and patient-specific antitumor activity (Borch TH et al. J Immunother Cancer. 2020;8:e000668). Made from each patient’s digested and cryopreserved tumor, ITIL-168 is an autologous TIL cell therapy manufactured to offer an unrestricted T-cell receptor repertoire. A single-center, compassionate use clinical series demonstrated the feasibility and clinical utility of an earlier version of ITIL-168, with a high overall response rate among pts previously treated with PD-1 inhibitor (PD-1i) therapy (58%, n = 12; Pillai M et al. Ann Oncol. 2021;32[suppl 5]:S882). DELTA-1 (NCT05050006) is a global, multicenter phase 2 study to evaluate efficacy and safety of ITIL-168 in pts with cutaneous melanoma relapsed or refractory to a PD-1i, pts intolerant to a PD-1i, and pts whose current best response to a PD-1i is stable disease. Methods: Pts aged ≥18 years with histologically confirmed advanced cutaneous melanoma, ECOG performance status 0-1, and adequate organ function will be enrolled in 1 of 3 cohorts. Cohort 1 (n≈80) will include pts who relapsed after or were refractory to ≥1 prior line of systemic therapy, including a PD-1i and, if BRAF-mutated, a BRAFi ± MEKi. Cohorts 2 and 3 (n≈25 each) will include pts intolerant to PD-1i and those with stable disease after ≥4 doses of PD-1i, respectively. After tumor resection for TIL harvest, pts must have ≥1 remaining measurable lesion per RECIST 1.1. Pts with uveal, acral, or mucosal melanoma, prior allogeneic transplant or cell therapy, and with central nervous system (CNS) disorder or symptomatic and/or untreated CNS metastases are ineligible. Pts will receive 5 days of lymphodepleting chemotherapy (cyclophosphamide ×2 days overlapping with fludarabine ×5 days) followed by a single ITIL-168 infusion (≥5×109 cells) and supportive short-course, high-dose IL-2. The primary endpoint is objective response rate (ORR) per central review. Secondary endpoints include duration of response, progression-free survival, overall survival, disease control rate, TIL persistence, and safety. Hypothesis testing of ORR will be performed for cohort 1. The primary analysis will occur when all pts in the cohort 1 modified intent-to-treat population have been followed for ≥6 months after the first posttreatment disease assessment. DELTA-1 opened for enrollment in September 2021. Updated site information will be given at the time of presentation. Clinical trial information: NCT05050006.

Hallmarks of Resistance to Immune-Checkpoint Inhibitors

Immune-checkpoint inhibitors (ICI), although revolutionary in improving long-term survival outcomes, are mostly effective in patients with immune-responsive tumors. Most patients with cancer either do not respond to ICIs at all or experience disease progression after an initial period of response. Treatment resistance to ICIs remains a major challenge and defines the biggest unmet medical need in oncology worldwide. In a collaborative workshop, thought leaders from academic, biopharma, and nonprofit sectors convened to outline a resistance framework to support and guide future immune-resistance research. Here, we explore the initial part of our effort by collating seminal discoveries through the lens of known biological processes. We highlight eight biological processes and refer to them as immune resistance nodes. We examine the seminal discoveries that define each immune resistance node and pose critical questions, which, if answered, would greatly expand our notion of immune resistance. Ultimately, the expansion and application of this work calls for the integration of multiomic high-dimensional analyses from patient-level data to produce a map of resistance phenotypes that can be utilized to guide effective drug development and improved patient outcomes.

Association of Neutrophil-to-Lymphocyte Ratio with Efficacy of First-Line Avelumab plus Axitinib vs. Sunitinib in Patients with Advanced Renal Cell Carcinoma Enrolled in the Phase 3 JAVELIN Renal 101 Trial

PURPOSE

To evaluate the association between neutrophil-to-lymphocyte ratio (NLR) and efficacy of avelumab plus axitinib or sunitinib.

EXPERIMENTAL DESIGN

Adult patients with untreated advanced renal cell carcinoma (RCC) with a clear-cell component, ≥1 measurable lesions, Eastern Cooperative Oncology Group performance status of 0 or 1, fresh or archival tumor specimen, and adequate renal, cardiac, and hepatic function were included. Retrospective analyses of the association between baseline NLR and progression-free survival (PFS) and overall survival (OS) in the avelumab plus axitinib or sunitinib arms were performed using the first interim analysis of the phase 3 JAVELIN Renal 101 trial (NCT02684006). Multivariate Cox regression analyses of PFS and OS were conducted. Translational data were assessed to elucidate the underlying biology associated with differences in NLR.

RESULTS

Patients with below-median NLR had longer observed PFS with avelumab plus axitinib [stratified HR, 0.85; 95% confidence interval (CI), 0.634-1.153] or sunitinib (HR, 0.56; 95% CI, 0.415-0.745). In the avelumab plus axitinib or sunitinib arms, respectively, median PFS was 13.8 and 11.2 months in patients with below-median NLR, and 13.3 and 5.6 months in patients with median-or-higher NLR. Below-median NLR was also associated with longer observed OS in the avelumab plus axitinib (HR, 0.51; 95% CI, 0.300-0.871) and sunitinib arms (HR, 0.30; 95% CI, 0.174-0.511). Tumor analyses showed an association between NLR and key biological characteristics, suggesting a role of NLR in underlying mechanisms influencing clinical outcome.

CONCLUSIONS

Current data support NLR as a prognostic biomarker in patients with advanced RCC receiving avelumab plus axitinib or sunitinib.

HLA-A*03 and response to immune checkpoint blockade in cancer: an epidemiological biomarker study

BACKGROUND

Predictive biomarkers could allow more precise use of immune checkpoint inhibitors (ICIs) in treating advanced cancers. Given the central role of HLA molecules in immunity, variation at the HLA loci could differentially affect the response to ICIs. The aim of this epidemiological study was to determine the effect of HLA-A*03 as a biomarker for predicting response to immunotherapy.

METHODS

In this epidemiological study, we investigated the clinical outcomes (overall survival, progression free survival, and objective response rate) after treatment for advanced cancer in eight cohorts of patients: three observational cohorts of patients with various types of advanced tumours (the Memorial Sloan Kettering Integrated Mutation Profiling of Actionable Cancer Targets [MSK-IMPACT] cohort, the Dana-Farber Cancer Institute [DFCI] Profile cohort, and The Cancer Genome Atlas) and five clinical trials of patients with advanced bladder cancer (JAVELIN Solid Tumour) or renal cell carcinoma (CheckMate-009, CheckMate-010, CheckMate-025, and JAVELIN Renal 101). In total, these cohorts included 3335 patients treated with various ICI agents (anti-PD-1, anti-PD-L1, and anti-CTLA-4 inhibitors) and 10 917 patients treated with non-ICI cancer-directed therapeutic approaches. We initially modelled the association of HLA amino-acid variation with overall survival in the MSK-IMPACT discovery cohort, followed by a detailed analysis of the association between HLA-A*03 and clinical outcomes in MSK-IMPACT, with replication in the additional cohorts (two further observational cohorts and five clinical trials).

FINDINGS

HLA-A*03 was associated in an additive manner with reduced overall survival after ICI treatment in the MSK-IMPACT cohort (HR 1·48 per HLA-A*03 allele [95% CI 1·20-1·82], p=0·00022), the validation DFCI Profile cohort (HR 1·22 per HLA-A*03 allele, 1·05-1·42; p=0·0097), and in the JAVELIN Solid Tumour clinical trial for bladder cancer (HR 1·36 per HLA-A*03 allele, 1·01-1·85; p=0·047). The HLA-A*03 effect was observed across ICI agents and tumour types, but not in patients treated with alternative therapies. Patients with HLA-A*03 had shorter progression-free survival in the pooled patient population from the three CheckMate clinical trials of nivolumab for renal cell carcinoma (HR 1·31, 1·01-1·71; p=0·044), but not in those receiving control (everolimus) therapies. Objective responses were observed in none of eight HLA-A*03 homozygotes in the ICI group (compared with 59 [26·6%] of 222 HLA-A*03 non-carriers and 13 (17·1%) of 76 HLA-A*03 heterozygotes). HLA-A*03 was associated with shorter progression-free survival in patients receiving ICI in the JAVELIN Renal 101 randomised clinical trial for renal cell carcinoma (avelumab plus axitinib; HR 1·59 per HLA-A*03 allele, 1·16-2·16; p=0·0036), but not in those receiving control (sunitinib) therapy. Objective responses were recorded in one (12·5%) of eight HLA-A*03 homozygotes in the ICI group (compared with 162 [63·8%] of 254 HLA-A*03 non-carriers and 40 [55·6%] of 72 HLA-A*03 heterozygotes). HLA-A*03 was associated with impaired outcome in meta-analysis of all 3335 patients treated with ICI at genome-wide significance (p=2·01 × 10-8) with no evidence of heterogeneity in effect (I2 0%, 95% CI 0-0·76) INTERPRETATION: HLA-A*03 is a predictive biomarker of poor response to ICI. Further evaluation of HLA-A*03 is warranted in randomised trials. HLA-A*03 carriage could be considered in decisions to initiate ICI in patients with cancer.

FUNDING

National Institutes of Health, Merck KGaA, and Pfizer.

Avelumab in Combination with Axitinib as First-Line Treatment in Patients with Advanced Hepatocellular Carcinoma: Results from the Phase 1b VEGF Liver 100 Trial

INTRODUCTION

Combining an immune checkpoint inhibitor with a targeted antiangiogenic agent may leverage complementary mechanisms of action for the treatment of advanced/metastatic hepatocellular carcinoma (aHCC). Avelumab is a human anti-PD-L1 IgG1 antibody with clinical activity in various tumor types; axitinib is a selective tyrosine kinase inhibitor of vascular endothelial growth factor receptors 1, 2, and 3. We report the final analysis from VEGF Liver 100 (NCT03289533), a phase 1b study evaluating safety and efficacy of avelumab plus axitinib in treatment-naive patients with aHCC.

METHODS

Eligible patients had confirmed aHCC, no prior systemic therapy, ≥1 measurable lesion, Eastern Cooperative Oncology Group performance status ≤1, and Child-Pugh class A disease. Patients received avelumab 10 mg/kg intravenously every 2 weeks plus axitinib 5 mg orally twice daily until progression, unacceptable toxicity, or withdrawal. Endpoints included safety and investigator-assessed objective response per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 and modified RECIST (mRECIST) for HCC.

RESULTS

Twenty-two Japanese patients were enrolled and treated with avelumab plus axitinib. The minimum follow-up was 18 months as of October 25, 2019 (data cutoff). Grade 3 treatment-related adverse events (TRAEs) occurred in 16 patients (72.7%); the most common (≥3 patients) were hypertension (n = 11 [50.0%]), palmar-plantar erythrodysesthesia syndrome (n = 5 [22.7%]), and decreased appetite (n = 3 [13.6%]). No grade 4 TRAEs or treatment-related deaths occurred. Ten patients (45.5%) had an immune-related AE (irAE) of any grade; 3 patients (13.6%) had an infusion-related reaction (IRR) of any grade, and no grade ≥3 irAE and IRR were observed. The objective response rate was 13.6% (95% CI: 2.9-34.9%) per RECIST 1.1 and 31.8% (95% CI: 13.9-54.9%) per mRECIST for HCC.

CONCLUSION

Treatment with avelumab plus axitinib was associated with a manageable toxicity profile and showed antitumor activity in patients with aHCC.

Efficacy and correlative analyses of avelumab plus axitinib versus sunitinib in sarcomatoid renal cell carcinoma: post hoc analysis of a randomized clinical trial

BACKGROUND

Among patients with advanced renal cell carcinoma (RCC), those with sarcomatoid histology (sRCC) have the poorest prognosis. This analysis assessed the efficacy of avelumab plus axitinib versus sunitinib in patients with treatment-naive advanced sRCC.

METHODS

The randomized, open-label, multicenter, phase III JAVELIN Renal 101 trial (NCT02684006) enrolled patients with treatment-naive advanced RCC. Patients were randomized 1 : 1 to receive either avelumab plus axitinib or sunitinib following standard doses and schedules. Assessments in this post hoc analysis of patients with sRCC included efficacy (including progression-free survival) and biomarker analyses.

RESULTS

A total of 108 patients had sarcomatoid histology and were included in this post hoc analysis; 47 patients in the avelumab plus axitinib arm and 61 in the sunitinib arm. Patients in the avelumab plus axitinib arm had improved progression-free survival [stratified hazard ratio, 0.57 (95% confidence interval, 0.325-1.003)] and a higher objective response rate (46.8% versus 21.3%; complete response in 4.3% versus 0%) versus those in the sunitinib arm. Correlative gene expression analyses of patients with sRCC showed enrichment of gene pathway scores for cancer-associated fibroblasts and regulatory T cells, CD274 and CD8A expression, and tumors with The Cancer Genome Atlas m3 classification.

CONCLUSIONS

In this subgroup analysis of JAVELIN Renal 101, patients with sRCC in the avelumab plus axitinib arm had improved efficacy outcomes versus those in the sunitinib arm. Correlative analyses provide insight into this subtype of RCC and suggest that avelumab plus axitinib may increase the chance of overcoming the aggressive features of sRCC.

Integrating peripheral biomarker analyses from JAVELIN Renal 101: Avelumab + axitinib (A + Ax) versus sunitinib (S) in advanced renal cell carcinoma (aRCC)

4547

Background: In the phase 3 JAVELIN Renal 101 trial (NCT02684006), treatment-naive patients (pts) with aRCC demonstrated prolonged progression-free survival (PFS) and a higher objective response rate with A + Ax vs S. We report the association of blood-based biomarkers with differential responses to treatment. Methods: Biomarkers in pretreatment (pre-tx) and on-treatment (on-tx) blood samples from 886 enrolled pts were correlated with clinical outcomes and molecular profiling data from corresponding tumor samples. Analyses include blood counts of unique populations, T-cell receptor sequencing, circulating cytokines, and serum proteomics by mass spectrometry MALDI-TOF. Results: At baseline, higher pre-tx monocyte counts were associated with shorter PFS in the A + Ax arm (Table). In the S arm, higher pre-tx levels of multiple T-cell–related metrics, including the percent of productively rearranged peripheral T cells, were associated with longer PFS but had no association in the A + Ax arm (Table). Higher pre-tx neutrophil counts were associated with shorter PFS in both arms, but neutrophil-to-lymphocyte ratio (NLR) was only associated with PFS for the S arm (Table). On-therapy biomarkers showed differential post-tx changes in T-cell numbers and clones at C2D1. Tx-specific differences were also seen in non–T-cell populations such as monocytes and neutrophils at multiple time points through C3D1. Serum levels of pre- and on-tx VEGF, CRP, and several interleukins showed differential associations with PFS (eg, higher pre-tx VEGF was associated with shorter PFS in only the S arm) (Table). Specific genomic alterations in tumor tissues were associated with differences in several pre- and on-tx angiokines & cytokines. Conclusions: Response to treatment with first-line A + Ax or S was associated with immune fitness and tx-specific immunomodulation. We identified peripheral biomarkers in pts with aRCC associated with the presence of impactful genomic alterations and differential clinical outcomes. Clinical trial information: NCT02684006. [Table: see text]

Molecular characteristics of renal cell carcinoma (RCC) risk groups from JAVELIN Renal 101

744

Background: The phase 3 JAVELIN Renal 101 trial in patients (pts) with advanced RCC demonstrated a progression-free survival (PFS) benefit and higher objective response rate (ORR) with avelumab + axitinib (A+Ax) vs sunitinib (S) (Motzer NEJM 2019). PFS and ORR favored A+Ax in all MSKCC risk groups, but median PFS varied. Here, we report results from analyses of baseline tumor samples to define molecular characteristics underlying risk group classifications. Methods: Nephrectomy or tumor samples from pts enrolled in the study were characterized by immunohistochemistry (CD8 and PD-L1), whole exome sequencing, or gene expression profiling (n = 705–850). Gene expression signatures (GES), pathway activation status, and mutational profiles were examined in relation to MSKCC risk groups. Results: Of the 886 total pts enrolled, 23%, 66%, and 11% had favorable (F), intermediate (I), or poor (P) MSKCC risk factors at baseline. In the F, I, and P groups, the ORR was 66%/38%, 50%/24%, and 31%/9%; median PFS was NR/16.7 mo, 13.3 mo/7.9 mo, and 5.6 mo/2.8 mo for the A+Ax/S arms, respectively. Neither the presence of PD-L1+ immune cells nor CD8+ cells differentiated the subgroups; however, the presence of PD-L1+ tumor cells was highest in the P group (p=0.0159). When compared to the I and P groups, the F group was enriched for NOTCH2 mutations (p=0.0002), displayed high FLT1 expression (p=0.007), and showed a trend favoring angiogenesis GES (JAVELIN Renal 101 and IMmotion150). The I group displayed few distinguishing characteristics (low neutrophil GES [p=0.02] and elevated homeobox gene expression [p=0.00052]). Relative to the F group, the P group showed higher cell cycle gene expression (p=0.0057) and PTEN mutation frequency, wild-type NOTCH2 genotype, elevated IMmotion150 Myeloid inflamed GES (p=0.0024), and macrophage-specific GES (p=0.0327), as well as GES for TH2 (p=0.0002), hypoxia (p=0.0199), glycolysis (p=0.0066), and the lowest expression of a dendritic cell GES (p=0.0209). Conclusions: In advanced RCC patients, biological differences within each MSKCC risk category may impact response to treatment and may help explain why these groups perform differently. Clinical trial information: NCT02684006.

Biomarker analyses from JAVELIN Renal 101: Avelumab + axitinib (A+Ax) versus sunitinib (S) in advanced renal cell carcinoma (aRCC)

101

Background: The phase 3 JAVELIN Renal 101 trial in previously untreated patients (pts) with aRCC demonstrated a progression-free survival (PFS) benefit and higher objective response rate with A+Ax vs S (Motzer, ESMO 2018; LBA6_PR). Here, we report outcomes from biomarker analyses of baseline tumor samples. Methods: We correlated efficacy with the results of molecular analyses of tissue samples from all 886 pts enrolled in JAVELIN Renal 101. Nephrectomy or tumor samples were characterized by immunohistochemistry (CD8 and PD-L1), whole-exome sequencing (WES), and RNAseq. WES and RNAseq were used to examine somatic mutations and analyze relevant gene expression signatures (GES) in relation to clinical outcomes. GES analyses included published and de novo signatures: effector T cell (Teff), angiogenesis (angio),T cell-inflamed (Tinf), and a novel immune-related signature incorporating pathway indicators for T- and NK-cell activation and IFNγ signaling, among others. Results: PD-L1 expression (≥1% immune cells) was associated with the longest PFS in the A+Ax arm and the shortest in the S arm (HR, 0.63; 95% CI, 0.49, 0.81). Significant treatment arm–specific differences in PFS were observed relative to wildtype when mutations in genes such as CD1631L, PTEN, or DNMT1 were present. Tumor mutational burden did not distinguish pts with respect to PFS. High-angio GES was associated with significantly improved PFS in the S arm but did not differentiate PFS in the A+Ax arm. In the low-angio subset, A+Ax improved PFS vs S. Pts with high Teff and Tinf in the A+Ax arm had longer PFS vs the S arm. In the A+Ax arm, PFS was enhanced in patients with immune GES–positive tumors vs those in the negative group (HR, 0.63; 95% CI, 0.46, 0.86; 2-sided p = 0.004), as well as in an independent dataset (JAVELIN Renal 100; Choueiri, Lancet Oncol, 2018) (HR, 0.46; 95% CI, 0.20, 1.05; 2-sided p = 0.064). Updated efficacy, including overall survival, will be presented. Conclusions: These findings define molecular features that differentiate therapy-specific outcomes in first-line aRCC and may inform personalized therapy strategies for pts with aRCC. Funding: Pfizer and Merck KGaA. Clinical trial information: NCT02684006.

First-line avelumab + axitinib in patients with advanced hepatocellular carcinoma: Results from a phase 1b trial (VEGF Liver 100)

4072

Background: Combining an immune checkpoint inhibitor with a targeted antiangiogenic agent may leverage complementary mechanisms of action for treatment of advanced/metastatic (a/m) hepatocellular carcinoma (HCC). Avelumab is a human anti–PD-L1 IgG1 antibody with clinical activity in various tumor types; axitinib is a tyrosine kinase inhibitor selective for VEGF receptors 1/2/3. VEGF Liver 100 (NCT03289533) is a phase 1b study evaluating safety and efficacy of avelumab + axitinib in treatment-naive patients (pts) with HCC; interim results are reported here. Methods: Eligible pts had confirmed a/m HCC, ≥1 measurable lesion, a fresh or archival tumor specimen, ECOG PS ≤1, and Child-Pugh class A. Pts received avelumab 10 mg/kg IV Q2W + axitinib 5 mg orally BID until progression, unacceptable toxicity, or withdrawal. Endpoints included safety and objective response (RECIST v1.1; modified [m] RECIST for HCC). Results: Interim assessment was performed after a minimum follow up of 6 months based on the released study data set (clinical cut-off date: Aug 1, 2018). As of the cut-off date, 22 pts (median age: 68.5 y) were treated with avelumab (median: 20.0 wk) and axitinib (median: 19.9 wk). The most common grade 3 treatment-related adverse events (TRAEs) (≥10% of patients) were hypertension (50.0%) and hand-foot syndrome (22.7%); no grade 4/5 TRAEs were reported. Immune-related AEs (irAEs) (≥10% of pts) were hypothyroidism (31.8%) and hyperthyroidism (13.6%). No grade ≥3 irAEs were reported; no pts discontinued treatment due to TRAEs or irAEs. Based on Waterfall plot calculations, tumor shrinkage was observed in 15 (68.2%) and 16 (72.7%) pts by RECIST and mRECIST, respectively. ORR was 13.6% (95% CI, 2.9%-34.9%) and 31.8% (95% CI, 13.9%-54.9%) by RECIST and mRECIST, respectively. OS data were immature at data cutoff. Conclusions: The preliminary safety of avelumab + axitinib in HCC is manageable and consistent with the known safety profiles of avelumab and axitinib when administered as monotherapies. This study demonstrates antitumor activity of the combination in HCC. Follow-up is ongoing. Clinical trial information: NCT03289533. [Table: see text]

Avelumab plus Axitinib versus Sunitinib for Advanced Renal-Cell Carcinoma

BACKGROUND

In a single-group, phase 1b trial, avelumab plus axitinib resulted in objective responses in patients with advanced renal-cell carcinoma. This phase 3 trial involving previously untreated patients with advanced renal-cell carcinoma compared avelumab plus axitinib with the standard-of-care sunitinib.

METHODS

We randomly assigned patients in a 1:1 ratio to receive avelumab (10 mg per kilogram of body weight) intravenously every 2 weeks plus axitinib (5 mg) orally twice daily or sunitinib (50 mg) orally once daily for 4 weeks (6-week cycle). The two independent primary end points were progression-free survival and overall survival among patients with programmed death ligand 1 (PD-L1)-positive tumors. A key secondary end point was progression-free survival in the overall population; other end points included objective response and safety.

RESULTS

A total of 886 patients were assigned to receive avelumab plus axitinib (442 patients) or sunitinib (444 patients). Among the 560 patients with PD-L1-positive tumors (63.2%), the median progression-free survival was 13.8 months with avelumab plus axitinib, as compared with 7.2 months with sunitinib (hazard ratio for disease progression or death, 0.61; 95% confidence interval [CI], 0.47 to 0.79; P<0.001); in the overall population, the median progression-free survival was 13.8 months, as compared with 8.4 months (hazard ratio, 0.69; 95% CI, 0.56 to 0.84; P<0.001). Among the patients with PD-L1-positive tumors, the objective response rate was 55.2% with avelumab plus axitinib and 25.5% with sunitinib; at a median follow-up for overall survival of 11.6 months and 10.7 months in the two groups, 37 patients and 44 patients had died, respectively. Adverse events during treatment occurred in 99.5% of patients in the avelumab-plus-axitinib group and in 99.3% of patients in the sunitinib group; these events were grade 3 or higher in 71.2% and 71.5% of the patients in the respective groups.

CONCLUSIONS

Progression-free survival was significantly longer with avelumab plus axitinib than with sunitinib among patients who received these agents as first-line treatment for advanced renal-cell carcinoma. (Funded by Pfizer and Merck [Darmstadt, Germany]; JAVELIN Renal 101 ClinicalTrials.gov number, NCT02684006.).

Use of TMB and PD-L1 to predict outcomes of checkpoint inhibitor treatment

150

Background: Medical practice is moving toward a more tailored, patient-centric one with precision medicine (biomarker)-guided therapies. Studies have evaluated ways of applying precision medicine to cancer therapies, and the use of several biomarkers has shown promise. The potential value of tumor mutational burden (TMB) and/or programmed death-ligand 1 (PD-L1) biomarkers to enhance the prediction of which patients are most likely to respond to checkpoint inhibitors has been explored in many studies. The objective of this literature review was to identify and summarize these studies. Methods: Literature searches were performed using electronic medical databases (MEDLINE, Embase, and BIOSIS) and internet searches of specified sites. Bibliographies of key systematic literature reviews and meta-analyses were reviewed for studies of interest. Due to the volume of literature for various cancer types, studies with a sample size of <50 patients were excluded. Results: The review identified 27 trials in non-small cell lung cancer (NSCLC), 39 trials in melanoma, 10 trials in urothelial cancer, and 5 trials in renal cell cancer indications. Studies also were identified in other cancer types (eg, colorectal, breast, and gastric cancer and Merkel cell carcinoma [MCC]). TMB as a predictor of outcomes was evaluated in 12 trials, including 6 in NSCLC. A TMB of ≥10 mutations per megabase was shown to be an effective biomarker in the CheckMate 227 study. PD-L1 was found to predict response in melanoma and all types of NSCLC other than squamous (Checkmate-017). However, prediction of response was not a prespecified analysis in some PD-L1 studies; other studies had small sample sizes and wide CIs. A clear predictive trend for PD-L1 was not identified in renal, breast, or gastric cancer or MCC. Conclusions: On the basis of the data in this review, assessment of TMB and PD-L1 biomarker expression may enhance the prediction of response to checkpoint inhibition in some tumors, such as NSCLC and melanoma. In this rapidly growing area of research, further exploratory biomarkers are being investigated, such as tumor-infiltrating lymphocytes and KRAS and BRAF mutations, that may provide insight on the potential efficacy of a treatment in a given patient.

Safety and efficacy of durvalumab in patients with head and neck squamous cell carcinoma: results from a phase I/II expansion cohort

INTRODUCTION

Durvalumab selectively blocks programmed cell death ligand-1 (PD-L1) binding to programmed cell death-1. Encouraging clinical activity and manageable safety were reported in urothelial carcinoma, non-small-cell lung cancer (NSCLC), hepatocellular carcinoma (HC) and small-cell lung cancer (SCLC) in a multicenter phase I/II study. Safety and clinical activity in recurrent/metastatic head and neck squamous cell carcinoma (HNSCC) were evaluated in the expansion phase.

METHODS

Patients received 10 mg/kg of durvalumab intravenously every 2 weeks for 12 months or until confirmed progressive disease or unacceptable toxicity. The primary objective was safety; clinical activity was a secondary objective.

RESULTS

Sixty-two patients were enrolled and evaluable (received first dose ≥24 weeks before data cutoff). Median age was 57 years; 40.3% were human papillomavirus (HPV)-positive; 32.3% had tumour cell PD-L1 expression ≥25%, and 62.9% were current/former smokers. They had a median of 2 prior systemic treatments (range, 1-13). All-causality adverse events (AEs) occurred in 98.4%; drug-related AEs occurred in 59.7% and were grade III-IV in 9.7%. There were no drug-related discontinuations or deaths. Objective response rate (blinded independent central review) was 6.5% (15.0% for PD-L1 ≥25%, 2.6% for <25%). Median time to response was 2.7 months (range, 1.2-5.5); median duration was 12.4 months (range, 3.5-20.5+). Median progression-free survival was 1.4 months; median overall survival (OS) was 8.4 months. OS rate was 62% at 6 months and 38% at 12 months (42% for PD-L1 ≥25%, 36% for <25%).

CONCLUSIONS

Durvalumab safety in HNSCC was manageable and consistent with other cohorts of the study. Early, durable responses in these heavily pretreated patients warrant further investigation; phase III monotherapy and combination therapy studies are ongoing. CLINICAL TRIAL REGISTRY: clinicaltrials.gov NCT01693562; MedImmune study 1108.

Preliminary results for avelumab plus axitinib as first-line therapy in patients with advanced clear-cell renal-cell carcinoma (JAVELIN Renal 100): an open-label, dose-finding and dose-expansion, phase 1b trial

BACKGROUND

The combination of an immune checkpoint inhibitor and a VEGF pathway inhibitor to treat patients with advanced renal-cell carcinoma might increase the clinical benefit of these drugs compared with their use alone. Here, we report preliminary results for the combination of avelumab, an IgG1 monoclonal antibody against the programmed cell death protein ligand PD-L1, and axitinib, a VEGF receptor inhibitor approved for second-line treatment of advanced renal-cell carcinoma, in treatment-naive patients with advanced renal-cell carcinoma.

METHODS

The JAVELIN Renal 100 study is an ongoing open-label, multicentre, dose-finding, and dose-expansion, phase 1b study, done in 14 centres in the USA, UK, and Japan. Eligible patients were aged 18 years or older (≥20 years in Japan) and had histologically or cytologically confirmed advanced renal-cell carcinoma with clear-cell component, life expectancy of at least 3 months, an Eastern Cooperative Oncology Group performance status of 1 or less, received no previous systemic treatment for advanced renal cell carcinoma, and had a resected primary tumour. Patients enrolled into the dose-finding phase received 5 mg axitinib orally twice daily for 7 days, followed by combination therapy with 10 mg/kg avelumab intravenously every 2 weeks and 5 mg axitinib orally twice daily. Based on the pharmacokinetic data from the dose-finding phase, ten additional patients were enrolled into the dose-expansion phase and assigned to this regimen. The other patients in the dose-expansion phase started taking combination therapy directly. The primary endpoint was dose-limiting toxicities in the first 4 weeks (two cycles) of treatment with avelumab plus axitinib. Safety and antitumour activity analyses were done in all patients who received at least one dose of avelumab or axitinib. This trial is registered with ClinicalTrials.gov, number NCT02493751.

FINDINGS

Between Oct 30, 2015, and Sept 30, 2016, we enrolled six patients into the dose-finding phase and 49 into the dose-expansion phase of the study. One dose-limiting toxicity of grade 3 proteinuria due to axitinib was reported among the six patients treated during the dose-finding phase. At the cutoff date (April 13, 2017), six (100%, 95% CI 54-100) of six patients in the dose-finding phase and 26 (53%, 38-68) of 49 patients in the dose-expansion phase had confirmed objective responses (32 [58%, 44-71] of all 55 patients). 32 (58%) of 55 patients had grade 3 or worse treatment-related adverse events, the most frequent being hypertension in 16 (29%) patients and increased concentrations of alanine aminotransferase, amylase, and lipase, and palmar-plantar erythrodysaesthesia syndrome in four (7%) patients each. Six (11%) of 55 patients died before data cutoff, five (9%) due to disease progression and one (2%) due to treatment-related autoimmune myocarditis. At the end of the dose-finding phase, the maximum tolerated dose established for the combination was avelumab 10 mg/kg every 2 weeks and axitinib 5 mg twice daily.

INTERPRETATION

The safety profile of the combination avelumab plus axitinib in treatment-naive patients with advanced renal-cell carcinoma seemed to be manageable and consistent with that of each drug alone, and the preliminary data on antitumour activity are encouraging. A phase 3 trial is assessing avelumab and axitinib compared with sunitinib monotherapy.

FUNDING

Pfizer and Merck.

Expression of PD-L1 and other immunotherapeutic targets in thymic epithelial tumors

Introduction

The thymus is a critical organ for the development of the adaptive immune system and thymic epithelial tumors (TETs; thymomas and thymic carcinomas) are often associated with auto-immune paraneoplastic conditions. However, the immunobiology of TETs is not well described. An evaluation of the tumor microenvironment, with particular focus on expression of immunotherapeutic targets, may facilitate and prioritize development of immunotherapy strategies for patients with TETs.

Methods

Tumor tissues from 23 patients with WHO Type B2/B3 thymoma (n = 12) and thymic carcinoma (n = 11) were identified and clinical outcomes were annotated. The expression of membranous PD-L1 on tumor cells, CD3+ and CD8+ tumor infiltrating lymphocytes (TILs), co-stimulatory (CD137, GITR, ICOS), and co-inhibitory immune checkpoint molecules (PD-1, CTLA-4, TIM-3) were assessed semi-quantitatively using immunohistochemistry.

Results

PD-L1 positivity (≥ 25% of tumor membrane expression) was frequent in TETs (15/23, 65%), more common in thymomas compared to thymic carcinomas (p<0.01), and was associated with longer overall survival (p = 0.02). TIM-3 and GITR were expressed in all TETs, including 18/23 and 12/23 with at least moderate/high expression, respectively. Moderate/high CD137 expression correlated with CD8+ (p = 0.01) and moderate/high GITR expression co-associated with PD-1 (p = 0.043).

Conclusions

TETs are characterized by frequent PD-L1 expression and PD-L1 is associated with improved survival, suggesting PD-L1 signaling may be biologically important in TETs. Robust expression of markers of immune activation and immunotherapeutic target molecules in TETs emphasizes the potential for development of anti-PD-1/PD-L1 therapies.

First-line avelumab + axitinib therapy in patients (pts) with advanced renal cell carcinoma (aRCC): Results from a phase Ib trial

4504

Background: Combining an immune checkpoint inhibitor with a targeted antiangiogenic agent may leverage complementary mechanisms of action for treatment of aRCC. Avelumab is a fully human anti–PD-L1 IgG1 antibody with clinical activity in various tumor types; axitinib, a VEGF receptor inhibitor, is approved for second-line treatment of aRCC. JAVELIN Renal 100 (NCT02493751) is a phase Ib study evaluating safety and clinical activity of avelumab + axitinib in treatment-naïve pts with aRCC; updated results are reported here. Methods: Eligible pts had confirmed clear-cell aRCC, ≥1 measurable lesion, fresh or archival tumor specimen, ECOG PS ≤1, and no prior systemic therapy. Pts received avelumab 10 mg/kg IV Q2W + axitinib 5 mg orally BID until progression, unacceptable toxicity, or withdrawal. Endpoints included safety (NCI CTCAE v4.03) and objective response (RECIST v1.1). Results: As of Dec 30, 2016, 55 pts (median age 60.0 yrs [range 42.0–76.0]; 76.4% male; 34.5% ECOG PS = 1) were enrolled. 54 pts were treated with avelumab for a median of 24.1 wks (range 2.0–62.0); 55 pts were treated with axitinib for a median of 25.3 wks (range 3.0-61.0). 51 pts (92.7%) had an avelumab-related adverse event (AE) with the therapy combination, the most common (≥30% any grade) were fatigue and diarrhea (30.9% each). 10 pts (18.2%) had a max grade 3 and 1 pt (1.8%) had a max grade 4 avelumab-related AE. 52 pts (94.5%) had an axitinib-related AE with the therapy combination; the most common (≥30% any grade) were diarrhea (52.7%), hypertension (45.5%), dysphonia (43.6%), and fatigue (43.6%). 24 pts (43.6%) had a max grade 3 and 5 pts (9.1%) had a max grade 4 axitinib-related AE. 2 deaths occurred in the study during the reporting period: 1 due to progression and 1 related to both treatments (myocarditis). An AE led to discontinuation of avelumab in 5 pts (9.1%) and axitinib in 4 pts (7.3%). Confirmed ORR was 54.5% (95% CI 40.6–68.0) based on 2 CR and 28 PR. Unconfirmed ORR was 60.0% (95% CI 45.9–73.0). Conclusions: The safety profile of the combination of avelumab + axitinib appears manageable and consistent with those agents administered as monotherapy, and early encouraging antitumor activity was observed. Follow-up is ongoing. Clinical trial information: NCT02493751.

Validation of biomarkers to predict response to immunotherapy in cancer: Volume I - pre-analytical and analytical validation

Immunotherapies have emerged as one of the most promising approaches to treat patients with cancer. Recently, there have been many clinical successes using checkpoint receptor blockade, including T cell inhibitory receptors such as cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programmed cell death-1 (PD-1). Despite demonstrated successes in a variety of malignancies, responses only typically occur in a minority of patients in any given histology. Additionally, treatment is associated with inflammatory toxicity and high cost. Therefore, determining which patients would derive clinical benefit from immunotherapy is a compelling clinical question.

Although numerous candidate biomarkers have been described, there are currently three FDA-approved assays based on PD-1 ligand expression (PD-L1) that have been clinically validated to identify patients who are more likely to benefit from a single-agent anti-PD-1/PD-L1 therapy. Because of the complexity of the immune response and tumor biology, it is unlikely that a single biomarker will be sufficient to predict clinical outcomes in response to immune-targeted therapy. Rather, the integration of multiple tumor and immune response parameters, such as protein expression, genomics, and transcriptomics, may be necessary for accurate prediction of clinical benefit. Before a candidate biomarker and/or new technology can be used in a clinical setting, several steps are necessary to demonstrate its clinical validity. Although regulatory guidelines provide general roadmaps for the validation process, their applicability to biomarkers in the cancer immunotherapy field is somewhat limited. Thus, Working Group 1 (WG1) of the Society for Immunotherapy of Cancer (SITC) Immune Biomarkers Task Force convened to address this need. In this two volume series, we discuss pre-analytical and analytical (Volume I) as well as clinical and regulatory (Volume II) aspects of the validation process as applied to predictive biomarkers for cancer immunotherapy. To illustrate the requirements for validation, we discuss examples of biomarker assays that have shown preliminary evidence of an association with clinical benefit from immunotherapeutic interventions. The scope includes only those assays and technologies that have established a certain level of validation for clinical use (fit-for-purpose). Recommendations to meet challenges and strategies to guide the choice of analytical and clinical validation design for specific assays are also provided.

Validation of biomarkers to predict response to immunotherapy in cancer: Volume II - clinical validation and regulatory considerations

There is growing recognition that immunotherapy is likely to significantly improve health outcomes for cancer patients in the coming years. Currently, while a subset of patients experience substantial clinical benefit in response to different immunotherapeutic approaches, the majority of patients do not but are still exposed to the significant drug toxicities. Therefore, a growing need for the development and clinical use of predictive biomarkers exists in the field of cancer immunotherapy. Predictive cancer biomarkers can be used to identify the patients who are or who are not likely to derive benefit from specific therapeutic approaches. In order to be applicable in a clinical setting, predictive biomarkers must be carefully shepherded through a step-wise, highly regulated developmental process. Volume I of this two-volume document focused on the pre-analytical and analytical phases of the biomarker development process, by providing background, examples and "good practice" recommendations. In the current Volume II, the focus is on the clinical validation, validation of clinical utility and regulatory considerations for biomarker development. Together, this two volume series is meant to provide guidance on the entire biomarker development process, with a particular focus on the unique aspects of developing immune-based biomarkers. Specifically, knowledge about the challenges to clinical validation of predictive biomarkers, which has been gained from numerous successes and failures in other contexts, will be reviewed together with statistical methodological issues related to bias and overfitting. The different trial designs used for the clinical validation of biomarkers will also be discussed, as the selection of clinical metrics and endpoints becomes critical to establish the clinical utility of the biomarker during the clinical validation phase of the biomarker development. Finally, the regulatory aspects of submission of biomarker assays to the U.S. Food and Drug Administration as well as regulatory considerations in the European Union will be covered.

Development of a programmed cell death ligand-1 immunohistochemical assay validated for analysis of non-small cell lung cancer and head and neck squamous cell carcinoma

Background

A high-quality programmed cell-death ligand 1 (PD-L1) diagnostic assay may help predict which patients are more likely to respond to anti-programmed cell death-1 (PD-1)/PD-L1 antibody-based cancer therapy. Here we describe a PD-L1 immunohistochemical (IHC) staining protocol developed by Ventana Medical Systems Inc. and key analytical parameters of its use in formalin-fixed, paraffin-embedded (FFPE) samples of non-small cell lung cancer (NSCLC) and head and neck squamous cell carcinoma (HNSCC).

Methods

An anti-human PD-L1 rabbit monoclonal antibody (SP263) was optimized for use with the VENTANA OptiView DAB IHC Detection Kit on the automated VENTANA BenchMark ULTRA platform. The VENTANA PD-L1 (SP263) Assay was validated for use with FFPE NSCLC and HNSCC tissue samples in a series of studies addressing sensitivity, specificity, robustness, and precision. Samples from a subset of 181 patients from a Phase 1/2 study of durvalumab (NCT01693562) were analyzed to determine the optimal PD-L1 staining cut-off for enriching the probability of responses to treatment. The scoring algorithm was defined using statistical analysis of clinical response data from this clinical trial and PD-L1 staining parameters in HNSCC and NSCLC tissue. Inter-reader agreement was established by three pathologists who evaluated 81 NSCLC and 100 HNSCC samples across the range of PD-L1 expression levels.

Results

The VENTANA PD-L1 (SP263) Assay met all pre-defined acceptance criteria. For both cancer types, a cut-off of 25 % of tumor cells with PD-L1 membrane staining of any intensity best discriminated responders from nonresponders. Samples with staining above this value were deemed to have high PD-L1 expression, and those with staining below it were deemed to have low or no PD-L1 expression. Inter-reader agreement on PD-L1 status was 97 and 92 % for NSCLC and HNSCC, respectively.

Conclusions

These results highlight the robustness and reproducibility of the VENTANA PD-L1 (SP263) Assay and support its suitability for use in the evaluation of NSCLC and HNSCC FFPE tumor samples using the devised ≥25 % tumor cell staining cut-off in a clinical setting. The clinical utility of the PD-L1 diagnostic assay as a predictive biomarker will be further validated in ongoing durvalumab studies.

Trial registration

ClinicalTrials.gov: NCT01693562

Abstract LB-228: Pharmacokinetics of Tremelimumab, a fully human anti-CTLA-4 monoclonal antibody, in subjects with unresectable malignant mesothelioma

Purpose: Tremelimumab is a fully human IgG2 monoclonal antibody specific for cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4/CD152). Tremelimumab blocks the interaction of CTLA-4 with its ligands B7.1 and B7.2, and enhances human T-cell activation, as demonstrated by increased interleukin-2 production in in-vitro/in-vivo studies. The primary objectives of this analysis were to assess the preliminary population pharmacokinetics (PK) of tremelimumab in mesothelioma and identify the impact of potential patient/disease characteristics on PK variability.

Methods: Tremelimumab serum concentration-time data were collected from a second-line, single-arm phase-2 study (NCT01649024/NCT01655888) designed to evaluate clinical activity along with safety and tolerability of multiple IV doses of tremelimumab in patients with malignant mesothelioma. Two dosing regimens were tested: 15 mg/kg every 90 days (Q90D) up to 4 doses in a 12 month period until progressive disease or unacceptable toxicity and, 10 mg/kg every 4 weeks (Q4W) for 6 months followed by 10 mg/kg every 12 weeks (Q12W) until progressive disease or unacceptable toxicity. A total of 40 subjects provided evaluable PK data at various prespecified time points following both dosing regimens. Tremelimumab serum concentrations were determined using a validated enzyme-linked immunosorbent assay (ELISA) with a lower limit of quantitation (LLOQ) of 0.156 µg/mL. PK analysis was performed using a non-linear mixed effects modeling approach with NONMEM 7.2 software.

Results: Tremelimumab PK exposure in mesothelioma subjects was similar to previous melanoma studies following 15 mg/kg Q90D. Following the 15 mg/kg Q90D, PK exposure was below the target trough level of ∼30 µg/mL for about half of the dosing interval with almost all subjects below the LLOQ at the end of the 90-day dosing interval. Following more frequent dosing of 10 mg/kg Q4W, PK exposure was increased and maintained at or above the target level in the majority of subjects over the entire dosing interval. Tremelimumab PK was best described using a 2-compartment linear model with first order elimination. Following IV dosing, the typical clearance (CL) and central volume of distribution (Vc) were 0.2 L/day and 3.5 L, respectively. The between-subject variability for CL and Vc were 22% and 7%, respectively. The estimated typical PK parameters were similar to other monoclonal antibodies without target mediated elimination. The baseline body weight and Eastern Cooperative Oncology Group (ECOG) performance status were identified as significant covariates for CL, whereas only baseline body weight was significant covariate for volume of distribution.

Conclusions: A 2-compartment population PK model adequately described tremelimumab PK in subjects with mesothelioma. PK parameter estimates were similar in both mesothelioma and melanoma populations. Tremelimumab 10 mg/kg Q4W yielded higher exposure than 15 mg/kg Q90D with a majority of subjects maintaining concentrations above the target trough level of ∼30 µg/mL over the dosing interval. Preliminary covariate screening identified body weight and ECOG as influential factors for PK parameters. These correlations will be further validated using data from larger clinical trials.

Citation Format: Luana Calabro', Rajesh Narwal, Paul B. Robbins, Alessandra Di Pietro, Ornella Cutaia, Ester Fonsatti, Diego Annesi, Carolina Fazio, Ramy Ibrahim, Michele Maio. Pharmacokinetics of Tremelimumab, a fully human anti-CTLA-4 monoclonal antibody, in subjects with unresectable malignant mesothelioma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-228. doi:10.1158/1538-7445.AM2014-LB-228

Abstract 4792: Biomarker discovery: Correlation of peripheral and tumoral markers in matched tumor and plasma samples

The heterogeneous nature of cancer necessitates the identification of markers to enable selection of appropriate patients for treatment and maximal clinical benefit. Archival tumor specimens are often analyzed for biomarkers, but may not reflect a patient's current state of disease. Predictive biomarkers from matrices amenable to longitudinal analyses and available through minimally invasive approaches could greatly improve patient outcomes by ensuring that the right patient receives the right drug. Peripheral markers are accessible and attractive, however, their relationship to tumoral markers, tumor biology as well as to primary or secondary clinical outcomes are not well understood. We examined the correlations among potential predictive biomarkers in these compartments by performing proteomic profiling of ∼300 analytes in 100 matched plasma and tumor tissue samples derived from patients with colorectal cancer (CRC), gastric, ovarian, and non-small cell lung cancer (NSCLC) of squamous cell carcinoma (SCC) or adenocarcinoma (ADC) histology. Using Luminex based assays, we identified markers which clearly distinguish each tumor type from another and may be useful for patient enrichment. VEGF has been implicated in processes essential to tumor growth and disease progression such as angiogenesis, vasculogenesis and hypoxia. Therefore, we examined the relationship between VEGF levels in plasma samples and tumor tissue within individual patients and explored the correlations among VEGF levels with those of other soluble proteins in the same matrices as well as with a marker of blood vessel formation in the tumors, microvessel density (MVD). We found the highest level of VEGF in the plasma of CRC patients but NSCLC patients displayed the highest level of VEGF in tumors. A poor correlation between tumoral or plasma VEGF levels was observed in all of the samples except for those from NSCLC SCC patients. MVD analysis of the tumors revealed that gastric and NSCLC ADC patients have a higher density of capillary vessels than other cancers. Surprisingly, no intra-patient correlation was detected between tumoral levels or plasma levels of VEGF and MVD. However, modest correlations between the MVD level in tumor tissues and select analytes in plasma have been observed for some tumor types. Further evaluation of these potential protein signatures in additional matched patient samples and animal disease models is warranted to generate clinically testable hypotheses for patient enrichment. The validity of these protein signatures as predictive markers for response to targeted therapies must be tested clinically. These novel and unexpected findings suggest that some peripheral markers may accurately represent the biology of the tumor and that matched sample analysis can provide an approach for biomarker discovery and hypothesis generation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4792. doi:1538-7445.AM2012-4792

Abstract 2543: PRLX 93936, is a potent, novel, tumor-selective, small molecule with a unique mechanism of action

Currently in Phase I testing, PRLX 93936 was developed and characterized at Prolexys Pharmaceuticals. It is a potent small molecule drug that shows robust and selective anti-cancer activity in a wide array of solid tumors including those with mutations that activate the RAS pathway. PRLX 93936 was chosen as a clinical lead as a result of extensive medicinal chemistry efforts and pharmacological profiling of over 400 novel small molecules. These compounds were designed to cover the chemical space originating from a molecule, Erastin, identified in a screen against isogenic cell lines differentially expressing genes such as those that activate the RAS pathway (Dolma et. al, Cancer Cell 3: 285-296, 2003). Cells that are sensitive to PRLX 93936 undergo caspase dependent apoptosis, necrosis, cell cycle arrest, ion flux and cell shrinkage leading to death and tumor growth inhibition. Characterization of drug treated cells shows that selective activation of RAS and JNK pathway members correlates with compound sensitivity. Research to elucidate the precise mechanism(s) and target(s) through which these biological responses are achieved has revealed that PRLX 93936's mechanism of action is unique. Several key lines of evidence support this conclusion including: 1. COMPARE analysis of PRLX 93936 activity in the NCI 60 panel of cell lines which showed that it is functionally distinct among the agents tested, 2. Profiling studies which examined PRLX 93936 binding or inhibition of enzyme activity against CYP450 enzymes, cell surface receptors and action potential mediating cardiac ion channels revealed only Cyp 3A4 and hERG as potential targets, 3. Kinase profiling of PRLX 93936 against evolutionarily diverse enzymes which identified no significant inhibitory activity, and 4. Genotyping and gene expression profiling studies which have yet to reveal a clear target profile correlation. Since the most common target classes were eliminated as potential suspects, additional non-traditional enzyme targets were screened for relevance to PRLX 93936 activity. Proteomics experiments identified the mitochondrial protein VDAC (Voltage Dependent Anion Channel) as a specific binding protein and potential molecular target of PRLX 93936 (Yagoda et al., Nature. 447: 865-869, 2007). More recent findings indicate that PRLX 93936 is a potent, selective inhibitor of several RAS pathway proteins including key enzymes which regulate the phosphorylation and activity of proteins involved in the RAS/JNK pathway. RNAi based validation studies and synergistic anti-cancer activity observed in combination with specific targeted drugs support these findings. PRLX 93936 may therefore represent a novel class of cancer therapeutics that target the majority of tumors characterized by RAS pathway activation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2543.

Use of human tissue to assess the oncogenic activity of melanoma-associated mutations

Multiple genetic alterations occur in melanoma, a lethal skin malignancy of increasing incidence. These include mutations that activate Ras and two of its effector cascades, Raf and phosphoinositide 3-kinase (PI3K). Induction of Ras and Raf can be caused by active N-Ras and B-Raf mutants as well as by gene amplification. Activation of PI3K pathway components occurs by PTEN loss and by AKT3 amplification. Melanomas also commonly show impairment of the p16(INK4A)-CDK4-Rb and ARF-HDM2-p53 tumor suppressor pathways. CDKN2A mutations can produce p16(INK4A) and ARF protein loss. Rb bypass can also occur through activating CDK4 mutations as well as by CDK4 amplification. In addition to ARF deletion, p53 pathway disruption can result from dominant negative TP53 mutations. TERT amplification also occurs in melanoma. The extent to which these mutations can induce human melanocytic neoplasia is unknown. Here we characterize pathways sufficient to generate human melanocytic neoplasia and show that genetically altered human tissue facilitates functional analysis of mutations observed in human tumors.

Peptide delivery to tissues via reversibly linked protein transduction sequences

The development of peptide-based therapeutics has suffered from challenges associated with delivery to intact tissue. In skin, an array of protein targets resides only tens of micrometers below the surface; however, because of difficulties in traversing the cutaneous barrier, the potentialfor peptide-based therapeutics remains unrealized. We have developed a general approach for topical peptide delivery into skin using releasable protein transduction sequences to enable peptide transport across tissue boundaries. Upon entry into the cell, the disulfide linkage between the peptide transduction sequences and peptide cargo is cleaved, permitting the dissociation of the highly charged peptide transduction sequences from the active peptide. A protype cargo peptide, the hemagglutinin (HA) epitope, was conjugated to a hepta-arginine protein transduction sequence via a releasable disulfide linkage. This construct penetrated the skin to deep dermis within 1 h after topical application. Consistent with the dissociation of the protein transduction and cargo sequences, absorbed protein transduction sequences and HA peptides displayed differential intracellular localization. Reversible protein transduction sequence linkage thus represents a noninvasive platform for tissue delivery of intact peptides with no requirement for viral vectors or parenteral injection and may be of broad utility in molecular therapy.

Sustainable systemic delivery via a single injection of lentivirus into human skin tissue

The skin offers a tissue site accessible for delivery of gene-based therapeutics. To develop the capability for sustained systemic polypeptide delivery via cutaneous gene transfer, we generated and injected pseudotyped HIV-1 lentiviral vectors intradermally at a range of doses into human skin grafted on immune-deficient mice. Unlike Moloney murine leukemia virus (MLV)-based retrovectors, which failed to achieve detectable cutaneous gene transfer by this approach, lentivectors effectively targeted all major cell types within human skin tissue, including fibroblasts, endothelial cells, keratinocytes, and macrophages. After a single injection, lentivectors encoding human erythropoietin (EPO) produced dose-dependent increases in serum human EPO levels and hematocrit that increased rapidly within one month and remained stable subsequently. Delivered gene expression was confined locally at the injection site. Excision of engineered skin led to rapid and complete loss of human EPO in the bloodstream, confirming that systemic EPO delivery was entirely due to lentiviral targeting of cells within skin rather than via spread of the injected vector to visceral tissues. These findings indicate that the skin can sustain dosed systemic delivery of therapeutic polypeptides via direct lentivector injection and thus provide an accessible and reversible approach for gene-based delivery to the bloodstream.

Impact of laminin 5 beta3 gene versus protein replacement on gene expression patterns in junctional epidermolysis bullosa

Molecular therapy studies to date have examined only a limited number of corrective parameters. To assess more global impacts on cellular gene expression for two major molecular therapeutic approaches, we compared gene versus protein delivery in the human genetic disease junctional epidermolysis bullosa (JEB). Both gene and protein replacement of the laminin 5 beta3 (beta3) adhesion molecule restored normal growth and adhesion to poorly viable JEB cells. Gene expression profiling was then performed using cDNA microarrays. The expression of more genes was normalized after beta3 gene transfer than after protein transfer. As anticipated for beta3 delivery, many of the genes whose expression was restored to the normal range were those encoding adhesion molecules and hemidesmosome components. Although gene transfer normalized the expression of a higher percentage of genes than did protein transfer, neither approach fully normalized expression of all genes examined. In addition, both approaches disrupted the expression of some genes, but protein transfer altered expression of a larger proportion of the genes studied. Our findings suggest that therapeutic gene and protein delivery may exert different effects on gene expression and thus may have implications for the development and analysis of molecular therapies for the treatment of genetic disorders.

In vivo restoration of laminin 5 beta 3 expression and function in junctional epidermolysis bullosa

The blistering disorder, lethal junctional epidermolysis bullosa (JEB), can result from mutations in the LAMB3 gene, which encodes laminin 5 beta3 (beta3). Appropriate expression of LAMbeta3 in JEB skin tissue could potentially ameliorate the symptoms of the underlying disease. To explore the utility of this therapeutic approach, primary keratinocytes from six unrelated JEB patients were transduced with a retroviral vector encoding beta3 and used to regenerate human skin on severe combined immunodeficient (SCID) mice. Tissue regenerated from beta3-transduced JEB keratinocytes produced phenotypically normal skin characterized by sustained beta3 expression and the formation of hemidesmosomes. Additionally, beta3 gene transfer corrected the distribution of a number of important basement membrane zone proteins including BPAG2, integrins beta4/beta1, and laminins alpha3/gamma2. Skin produced from beta3-negative (beta3[-]) JEB cells mimicked the hallmarks of the disease state and did not exhibit any of the aforementioned traits. Therefore, by effecting therapeutic gene transfer to beta3-deficient primary keratinocytes, it is possible to produce healthy, normal skin tissue in vivo. These data support the utility of gene therapy for JEB and highlight the potential for gene delivery in the treatment of human genetic skin disease.

Improved expression in hematopoietic and lymphoid cells in mice after transplantation of bone marrow transduced with a modified retroviral vector

Retroviral vectors based on the Moloney murine leukemia virus (MoMuLV) are currently the most commonly used vehicles for stable gene transfer into mammalian hematopoietic cells. But, even with reasonable transduction efficiency, expression only occurs in a low percentage of transduced cells and decreases to undetectable levels over time. We have previously reported the modified MND LTR (myeloproliferative sarcoma virus enhancer, negative control region deleted, dl587rev primer-binding site substituted) to show increased expression frequency and decreased methylation in transduced murine embryonic stem cells and hematopoietic stem cells. We have now compared expression of the enhanced green fluorescent protein (eGFP) from a vector using the MoMuLV LTR (LeGFPSN) with that from the modified vector (MNDeGFPSN) in mature hematopoietic and lymphoid cells in the mouse bone marrow transplant (BMT) model. In primary BMT recipients, we observed a higher frequency of expression from the MND LTR (20% to 80%) in hematopoietic cells of all lineages in spleen, bone marrow, thymus, and blood compared with expression from the MoMuLV LTR (5% to 10%). Expression from the MND LTR reached 88% in thymic T lymphocytes and 54% in splenic B lymphocytes for up to 8 months after BMT. The mean fluorescence intensity of the individual cells, indicating the amount of protein synthesized, was 6- to 10-fold higher in cells expressing MNDeGFPSN compared with cells expressing LeGFPSN. Transduction efficiencies determined by DNA polymerase chain reaction of vector copy number were comparable for the 2 vectors. Therefore, the MND vector offers an improved vehicle for reliable gene expression in hematopoietic cells.

High-resolution analysis of cytosine methylation in the 5ĺong terminal repeat of retroviral vectors

Retroviral vectors based on the Moloney murine leukemia virus (Mo-MuLV) are among the most commonly used vectors for stable gene transfer into mammalian cells. However, expression from the transcription unit of the Mo-MuLV long terminal repeat (LTR) has often been unsatisfactory. Transcriptional suppression of retroviral vectors in vitro in embryonal carcinoma (EC) cells and in vivo in hematopoietic stem cells (HSCs) has been associated with increased levels of cytosine methylation in the vector 5' LTR. To obtain a comprehensive picture of the methylation pattern in the 5' LTR of retroviral vectors, we employed the bisulfite genomic sequencing technique, which allows detection of the methylation pattern of every CpG dinucleotide in a target sequence. We studied the 5' LTR within the Mo-MuLV-based vector, LN, and a series of multiply modified vectors, which show improved expression in vitro and in vivo. Methylation patterns of the vectors were compared in PA317 (3T3-derived) fibroblasts, which are permissive for expression from all of the vectors, and in F9 embryonal carcinoma (EC) cells, which are restrictive for expression from the parental Mo-MuLV LTR but show improved expression from the modified vectors. These analyses revealed that the levels of methylation of CpG dinucleotides were globally consistent throughout the entire LTR, including the region of transcriptional factor binding. All vectors showed no measurable methylation of CpG dinucleotides throughout the 5' LTR in the PA317 fibroblasts. The CpG dinucleotides of the standard Mo-MuLV-based vector (LN) were highly methylated in F9 EC cells (49.1%). The doubly modified vector, MD-neo, which did not show improved expression, exhibited a relatively high level of methylation (45%), similar to that found in the LN vector. In contrast, the CpG dinucleotides of the triply modified vectors, which showed improved expression in EC cells (MND-neo and MTD-neo), were much less methylated (26.2 and 23.4%, respectively). The results extend our previous findings of an inverse correlation between gene expression and methylation of cytosine residues of the LTR of retroviral vectors.