A Phase II Study of High-Flow Nasal Cannula for Relieving Dyspnea in Advanced Cancer Patients

CONTEXT

The efficacy and tolerability of high-flow nasal cannula (HFNC) for relieving dyspnea in advanced cancer patients with limited prognosis requires elucidation.

OBJECTIVES

The primary aim of this trial was to assess the efficacy and tolerability of HFNC regarding dyspnea including severe as well as moderate for longer durations in patients under palliative care.

METHODS

In this prospective study, hospitalized patients with advanced cancer who had dyspnea at rest (numeric rating scale, NRS≥3) and hypoxemia were enrolled. They were treated with HFNC for five days in the respiratory unit. Primary endpoint was mean change of modified Borg scale at 24 hours. Key secondary endpoints consisted of mean changes in modified Borg scale during the study period and feasibility (Trial Identifier, UMIN000035738).

RESULTS

Between February 2019 and February 2022, 25 patients were enrolled and 21 were analyzed. Twenty patients used inspired oxygen and the mean fraction of inspired oxygen (FiO2) was 0.34 (range, 0.21-1.0). At baseline, mean NRS (dyspnea) was 5.9 (range, 3-10). Median survival time was 19 days (range, 3-657). The mean change of modified Borg scale was 1.4 (80% confidence interval [CI]: 0.8-1.9) at 24 hours, 12 patients (57%) showed 1.0 points improvement of modified Borg scale. Within two hours, 15 patients showed 1.0 points improvement of modified Borg scale and such early responders were likely to maintain dyspnea improvement for 24 hours. Nineteen patients could continue HFNC for 24 hours and 11 patients completed five days of HFNC.

CONCLUSION

To our knowledge, this trial is the first prospective study to assess the five-day efficacy and tolerability of HFNC for dyspnea in patients under palliative care. Although this did not reach the prespecified endpoint, about half of the patients showed 1.0 point improvement, a minimally clinically important difference (MCID) in the chronic lung disease. HFNC can be a palliative treatment option in advanced cancer patients with dyspnea.

First-Line Genomic Profiling in Previously Untreated Advanced Solid Tumors for Identification of Targeted Therapy Opportunities

IMPORTANCE

Precision oncology using comprehensive genomic profiling (CGP) by next-generation sequencing is aimed at companion diagnosis and genomic profiling. The clinical utility of CGP before the standard of care (SOC) is still not resolved, and more evidence is needed.

OBJECTIVE

To investigate the clinical utility of next-generation CGP (FoundationOne CDx [F1CDx]) in patients with previously untreated metastatic or recurrent solid tumors.

DESIGN, Setting, and Participants

This multicenter, prospective, observational cohort study enrolled patients with previously untreated advanced solid tumors between May 18, 2021, and February 16, 2022, with follow-up through August 16, 2022. The study was conducted at 6 hospitals in Japan. Eligible patients were aged 20 years or older and had Eastern Cooperative Oncology Group performance status of 0 to 1 with previously untreated metastatic or recurrent cancers in the gastrointestinal or biliary tract; pancreas, lung, breast, uterus, or ovary; and malignant melanoma.

EXPOSURE

Comprehensive genomic profiling testing before SOC for advanced solid tumors.

MAIN OUTCOMES AND MEASURES

Proportion of patients with actionable or druggable genomic alterations and molecular-based recommended therapy (MBRT).

RESULTS

A total of 183 patients met the inclusion criteria and 180 patients (92 men [51.1%]) with a median age of 64 years (range, 23-88 years) subsequently underwent CGP (lung [n = 28], colon/small intestine [n = 27], pancreas [n = 27], breast [n = 25], biliary tract [n = 20], gastric [n = 19], uterus [n = 12], esophagus [n = 10], ovary [n = 6], and skin melanoma [n = 6]). Data from 172 patients were available for end point analyses. Actionable alterations were found in 172 patients (100.0%; 95% CI, 97.9%-100.0%) and druggable alternations were identified in 109 patients (63.4%; 95% CI, 55.7%-70.6%). The molecular tumor board identified MBRT for 105 patients (61.0%; 95% CI, 53.3%-68.4%). Genomic alterations included in the companion diagnostics list of the CGP test were found in 49 patients (28.5%; 95% CI, 21.9%-35.9%) in a tumor-agnostic setting. After a median follow-up of 7.9 months (range, 0.5-13.2 months), 34 patients (19.8%; 95% CI, 14.1%-26.5%) received MBRT.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that CGP testing before SOC for patients with advanced solid tumors may be clinically beneficial to guide the subsequent anticancer therapies, including molecularly matched treatments.

Abstract 516: N-glycan moiety of IgG-Fc region is a prognostic biomarker for advancednon-small cell lung cancertreated with immune checkpoint inhibitors

Background: Although it has been known that N-glycan moiety in immunoglobulin G (IgG) fragment crystallizable (Fc) region, which affects antigen dependent cellular cytotoxicity (ADCC) activity is different between healthy individuals and cancer patients, the impact of N-glycan structure on cancer treatment is unknown. Here, we evaluated the putative ADCC activity by the N-glycan moiety of IgG-Fc using serum samples and analyzed its association with clinical benefits from immune checkpoint inhibitors (ICIs) in patients with advanced non-small cell lung cancer (NSCLC).

Patients and Methods: Serum samples from healthy volunteers (HVs) were obtained from Tohoku Medical Megabank and chronic obstructive pulmonary disease (COPD) patients were enrolled as a smoking-related non-cancer disease cohort. Serum samples from advanced NSCLC patients receiving ICIs until disease progression or unacceptable toxicity were collected prior treatment. Three IgG fractions (area 1, 2 and 3) corresponding to three peaks identified by affinity chromatography using TSKgel FcR-IIIA-NPR column (Tosoh, Japan) were quantified and the putative ADCC activity was estimated based on the ratio of area 3, which associates with highest ADCC activity, to the whole area (area 3 (%)). Mann-Whitney U-test, Kaplan-Meier methods and the log-rank test were conducted for statistical analyses using JMP Pro software (ver. 14.0).

Results: Forty-two COPD and ninty-six NSCLC patients were registered in the study between Jan 2016 and May 2021 at Wakayama Medical University. Characteristics of the patients were as follows: median age, 70 (range, 49-91); male. 78%; smoker, 79%; previous treatment ≥1, 77%; performance status 0-1, 82%; stage IV, 69%; squamous/non-squamous/unknown, 29/69/2%; nivolumab/pembrolizumab/atezolizumab, 46/42/12%. The objective response rate was 25.0% (24/96). The median progression free survival (PFS) and median overall survival (OS) was 72 days (95%CI, 49 to 127) and 310 days (95% CI, 216 to 453), respectively. The area 3 (%) was significantly lower in NSCLC patients than both HVs and COPD patients (P=0.0002 and p<0.0001, respectively) and no significant difference was observed between HVs and COPD samples. When time-to-event analysis was conducted by dividing into two groups in NSCLC patients at the median of the area 3 (%), OS was significantly longer in patient with higher ratio than those with lower one in both entire cohort (median OS, 952 vs 482; 95% CI, 453 days-not reached (NR) and 233-744 days; p=0.0236) and 2nd line subset (median OS, 952 vs 292; 95% CI, 453 days-NR and 120-692 days; p=0.001). Evaluation of IgG fraction was not associated with tumor response or PFS in this study cohort.

Conclusion: Our results suggest that evaluation of the N-glycan moiety of IgG-Fc in peripheral blood has a potential as a prognostic biomarker in advanced NSCLC patients treated with ICIs.

Citation Format: Jun Oyanagi, Yasuhiro Koh, Yasuyuki Akiyama, Atsushi Morimoto, Koichi Sato, Shunsuke Teraoka, Daichi Fujimoto, Nahomi Tokudome, Atsushi Hayata, Yuichi Ozawa, Hiroaki Akamatsu, Masanori Nakanishi, Hiroki Ueda, Nobuyuki Yamamoto. N-glycan moiety of IgG-Fc region is a prognostic biomarker for advancednon-small cell lung cancertreated with immune checkpoint inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 516.

Pre-treatment serum protein levels predict survival of non-small cell lung cancer patients without durable clinical benefit by PD-1/L1 inhibitors

While PD-1/L1 inhibitors are characterized by durable tumor control, they also prolong survival without prolongation of progression-free survival (PFS) in part of patients. However, little is known about the factors and mechanisms involved in this. Between December 2015 and September 2018, 106 patients with advanced non-small cell lung cancer treated with ICI monotherapy were enrolled in a prospective-observational study. Sixty-nine of whom progressed or died within 6 months after ICI initiation were defined as patients without durable clinical benefit (NDBs). Clinical factors and 39 serum proteins before ICI initiation and at the time of progressive disease (PD) were explored for an association with overall survival (OS) and OS after PD (OS-PD). As a result, median PFS, OS, and OS-PD were 44 days [95% confidence interval (CI): 39-56), 211 days (95% CI: 158-425), and 193 days (95% CI: 118-349), respectively. By multivariate analysis for OS, CRP (> 1.44 mg/dl) [HR 2.59 (95% CI:1.33-5.04), P = 0.005] and follistatin (> 685 pg/ml) [HR 2.29 (95% CI:1.12-4.69), P = 0.023] before ICI initiation were significantly predictive. Notably, no serum protein at the time of PD was predictive for OS-PD. There were also no serum predictive factors of OS in the 33 patients with durable clinical benefit. In conclusion, serum levels of CRP and follistatin before ICI initiation, not at the time of PD, are predictive for OS in NDBs, suggesting long-term survivor in NDBs are predetermined by the immune status before ICI initiation.

High-purity Isolation for Genotyping Rare Cancer Cells from Blood Using a Microfluidic Chip Cell Sorter

BACKGROUND/AIM

A multistep sorting method for enrichment of rare cells, such as circulating tumor cells, in the blood without cumbersome pretreatments required by most flow cytometry-based methods, which lead to high cost and decreased detection efficiency, was developed.

MATERIALS AND METHODS

After only hemolysis and cell staining, cancer cells are enriched by repetitive sorting (3×) based on nuclear-positive, cytokeratin-positive, and CD45-negative expression.

RESULTS

Experiments using spikes of PC-9 cells showed a mean recovery of 65% and mean purity of 83%, which was retained up to 72 hours after blood draw using preservative tubes. Significant differences in expression level of programmed death-ligand 1 or vimentin were observed between high- and low-expressing cell lines, concurrently with enrichment. Next-generation sequencing analysis of recovered PC-9, A549, and MDA-MB231 cells successfully detected all known mutations.

CONCLUSION

This novel isolation method applicable for preserved samples with sufficient recovery and purity may be substantially beneficial for recovering cells for subsequent molecular analysis.

Abstract P014: Clinical impact of evaluating serum IgG fractions in advanced non-small cell lung cancer treated with immune checkpoint inhibitors

Background: Structure of N-linked glycan in immunoglobulin G (IgG) fragment crystallizable (Fc) region is associated with antigen-dependent cellular cytotoxicity (ADCC) activity. Although it has been known that N-glycan moiety is different between healthy individuals and cancer patients, the relationship between the N-glycan structure and treatment response in cancer patients is unknown. Here, we evaluated the putative ADCC activity by the N-glycan moiety of IgG-Fc using peripheral blood and analyzed its association with clinical benefits from immune checkpoint inhibitors (ICIs) in patients with advanced non-small cell lung cancer (NSCLC). Patients and Methods: Advanced NSCLC patients received nivolumab, pembrolizumab or atezolizumab treatment until disease progression or unacceptable toxicity. Serum samples were collected at baseline. Tumor responses were classified into complete response (CR), partial response (PR), stable disease (SD), or progressive disease (PD) based on RECIST v1.1. Durable clinical benefit (DCB) was defined as patients whose response was lasting over 6 months. Three IgG fractions (area 1, 2 and 3) corresponding to three peaks identified by affinity chromatography using TSKgel FcR-IIIA-NPR column (Tosoh, Japan) were quantified and the putative ADCC activity was estimated based on the ratio of area 3, which associates with highest ADCC activity, to the whole area. All statistical analyses were carried out using JMP Pro software (ver. 14.0). Mann-Whitney U-test was conducted. Time to event analysis was conducted using Kaplan-Meier methods and the log-rank test. Results: Ninety-seven patients were registered in the study between Jan 2016 and Nov 2018 at Wakayama Medical University. Characteristics of the patients were as follows: median age, 70 (range, 49-91); male. 78%; smoker, 79%; previous treatment ≥1, 77%; performance status 0-1, 82%; stage III/IV, 31/69%; squamous/non-squamous/unknown, 29/69/2%; nivolumab/pembrolizumab/atezolizumab, 46/42/12%. The objective response rate was 25.0% (24/96) and the disease control rate was 55.2% (53/96). The DCB rate was 45.4% (44/96). The median progression free survival (PFS) was 72 days (95%CI, 49 to 127) and median overall survival (OS) was 310 days (95% CI, 229 to 475). When time-to-event analysis was conducted by dividing into two groups at the median of the ratio of area 3 to the whole area, OS was significantly longer in patient with higher ratio than those with lower one in both entire cohort (median OS, 952 vs 482; 95% CI, 482 days-not reached and 233-744 days; log rank p=0.0292) and 2nd line cohort (median OS, 952 vs 292; 95% CI, 453 days-not reached and 120-692 days; log rank p=0.0010). Evaluation of IgG fraction was not associated with tumor response or PFS in this study cohort. Conclusion: Our results suggest that evaluation of the N-glycan moiety of IgG-Fc in peripheral blood has a potential as a prognostic biomarker in advanced NSCLC patients treated with ICIs.

Citation Format: Jun Oyanagi, Yasuhiro Koh, Yasuyuki Akiyama, Atsushi Morimoto, Koichi Sato, Shunsuke Teraoka, Daichi Fujimoto, Nahomi Tokudome, Atsushi Hayata, Yuichi Ozawa, Hiroaki Akamatsu, Masanori Nakanishi, Hiroki Ueda, Nobuyuki Yamamoto. Clinical impact of evaluating serum IgG fractions in advanced non-small cell lung cancer treated with immune checkpoint inhibitors [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P014.

Abstract 2976: Establishment of organoids derived from patients with advanced thoracic malignancies

Background: In the past decade, three-dimensional organoid culture derived from various tumors has been applied to cancer research. Compared to the conventional two-dimensional cell culture, organoid culture recapitulates in vivo system and furthermore, its high establishment rate may hold the potential to help decision-making for precision medicine. However, it remains challenging to establish organoids from advanced thoracic malignancies due to a limited amount of biopsy specimens. Here, we report the attempt to establish organoids from endoscopic biopsy specimens and pleural effusions in patients with advanced thoracic malignancies

Methods: Organoid culture was attempted using biopsy specimens or pleural effusions from patients who underwent transbronchial biopsy, thoracoscopic biopsy or thoracentesis. After confirming the presence of malignant cells by rapid on-site evaluation, biopsy specimens were digested with collagenase and dispase at 37°C followed by being harvested and cultured in Matrigel. As for pleural effusions, mononuclear cells were isolated by ficoll density gradient centrifugation and CD45+ cells were depleted using anti-CD45 magnetic beads. Then, the resultant cells were cultured in Matrigel. Next-generation sequencing was performed to confirm cancer-related somatic mutations using Ion PGM system. Cell viability assay was performed by resazurin assay.

Results:142 patients were registered in the study between May 2019 and October 2020 at Wakayama Medical University. Fifty-one cases were excluded because of negative diagnosis for malignancy, retraction of the consent or risk of bleeding associated with biopsy. We attempted to culture organoids using 98 samples from 91 patients. The types of malignancies were as follows: non-small cell lung cancers (NSCLC)/SCLC/others, 80/8/3. A total of 33 organoids were successfully cultured with sustainable proliferation and 16 were successfully cryopreserved. Established organoids were confirmed to harbor the same mutations as detected by clinical testing with tissue samples and to form tumors in a xenotransplantation model. HLCO-75, established from pleural effusion at disease progression after osimertinib treatment was genotyped and found to gain ERBB2 V777L mutation in exon 20 in addition to original EGFR L858R mutation. Marked growth-inhibitory effect by poziotinib, a HER2 tyrosine kinase inhibitor with IC50 value 6 nM was observed whereas not by TAS6417, another EGFR/HER2 exon 20 inhibitor, suggesting the potential of organoid culture for decision-making in cancer precision medicine.

Conclusion: Our results suggest that organoid culture is feasible from small biopsy specimens and these organoids could be applied for personalized medicine.

Citation Format: Jun Oyanagi, Yasuhiro Koh, Koichi Sato, Masanori Tanaka, Katsuyuki Furuta, Takeya Sugimoto, Ryota Shibaki, Shunsuke Teraoka, Daichi Fujimoto, Nahomi Tokudome, Hiroaki Akamatsu, Atsushi Hayata, Atsushi Hayata, Yuichi Ozawa, Hiroki Ueda, Nobuyuki Yamamoto. Establishment of organoids derived from patients with advanced thoracic malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2976.

Tumor expression of cGAS, not STING, negatively impacts on the efficacy of PD-1/L1 inhibitors in non-small cell lung cancer with PD-L1 TPS ≥50

e21048

Background: The cGAS/STING pathway is an innate immune pathway that promotes cytokine production in response to cytoplasmic DNA, and its activation is important for the induction of anti-tumor immunity. However, predictivity of cGAS/STING tumor expression on the efficacy of PD-1/L1 inhibitors and subsequent immune responses (e.g., changes in serum cytokines) remain to be elucidated. Non-small cell lung cancer with PD-L1 tumor proportion score (TPS) of 50% or higher respond well to immune checkpoint inhibitor (ICI) monotherapy, but there is still a poor response group among them, and the extraction of such patients is an urgent issue. Methods: This is a post hoc analysis of prospective biomarker study, which enrolled 106 patients with advanced non-small cell lung cancer (NSCLC) who were treated with ICI monotherapy between December 2015 and September 2018. We investigated in 68 patients with preserved evaluable tissue samples taken before start of ICI treatment. cGAS, STING, and PD-L1 expression in tumors were stained by immunohistochemistry. cGAS and STING were evaluated by H-score. Using peripheral blood which was collected by the observational study, 41 serum proteins at the time of PD-1/L1 inhibitors initiation and in 4 – 6 weeks later were quantified. Results: The median cGAS and STING H-SCORE were 220 (5 – 300) and 190 (0 – 300), respectively. There were no differences in cGAS or STING H-SCORE between PD-L1 high (TPS ≥50) and low (TPS < 50) groups ( p= 0.990 and 0.283). Cases were divided into two groups according to median of the H-SCORE, respectively, and compared. Unexpectedly, cGAS high (H-SCORE ≥220) patients showed significantly shorter progression free survival of ICI when PD-L1 TPS ≥50 (median progression free survival (PFS); 143 days vs. not reached, p = 0.028) and progression free rate at 18 months was 7 and 53%, while no association was observed when PD-L1 TPS < 50 (median PFS; 47 vs. 61 days, p= 0.798). STING tumor expression was not associated with PFS regardless of PD-L1 TPS. In cytokine analysis, cGAS high was associated with significantly higher serum concentrations of TGF-β1 and β2 before ICI initiation (47.5 vs. 22.3hg/l, p= 0.023; 2118 vs. 882rg/ml, p= 0.037), and H-SCORE of cGAS, not STING, were significantly correlated with TGF-β1 and β2 basal levels (r = 0.447, p= 0.009; r = 0.373, p= 0.033). Analysis about fold change from baseline to 4 – 6 weeks later of 41 cytokines revealed that leptin significantly increased in cGAS high tumor while no difference was seen in all of cytokines between STING high and low tumor. Conclusions: Tumor expression (H-Score) of cGAS, not STING, is a candidate for predictor of poor response to ICI monotherapy in NSCLC with PD-L1 high (TPS ≥50). cGAS tumor expression may be associated with TGF-β producing, immune-suppressive tumor microenvironment in NSCLC. Clinical trial information: UMIN000024414.

Bloodborne Cytokines for Predicting Clinical Benefits and Immune-Related Adverse Events in Advanced Non-Small Cell Lung Cancer Treated With Anti-Programmed Cell Death 1 Inhibitors

BACKGROUND

Programmed cell death ligand 1 is a biomarker of immune checkpoint inhibitors (ICIs) for treating advanced non-small-cell lung cancer (NSCLC). Here, we evaluated serum proteins from patients with advanced NSCLC treated with ICIs to determine their potential as noninvasive predictive biomarkers for efficacy and immune-related adverse events (irAEs).

PATIENTS AND METHODS

Patients with advanced NSCLC who received nivolumab or pembrolizumab monotherapy until disease progression or unacceptable toxicity were integrated with previously reported nivolumab-treated patients. Blood samples were collected serially from baseline until the disease progressed. Serum protein levels were quantified using the Luminex assay. Associations of clinical benefit (CB) and onset of irAEs with serum protein levels were evaluated.

RESULTS

Sixty-three patients with advanced NSCLC were studied, and we used 63 and 47 paired serum samples at baseline and the second sampling point, respectively, for efficacy analysis. Baseline growth-regulated oncogene 1 (GRO-1) levels were significantly lower in durable CB (DCB) patients than in non-DCB patients (P < .05). Changes in monocyte chemoattractant protein 1 (MCP-1) levels significantly decreased between baseline and the second sampling point (P < .05). Patients with the low GRO-1/decreased MCP-1 subtype showed significantly longer progression-free survival (PFS) and overall survival (OS) than the high GRO-1/increased MCP-1 subgroup did (median PFS, not reached vs. 47 days, P < .0001; median OS, 985 days vs. 148 days, P = .0002, respectively). Elevated GRO-1 levels were associated with immune-related adverse event onset.

CONCLUSIONS

Serum GRO-1 and MCP-1 levels can identify patients with advanced NSCLC who are likely to benefit from ICI treatment. Time-course tracing of these protein levels might be valuable in ICI treatment.

CD24, not CD47, negatively impacts upon response to PD-1/L1 inhibitors in non-small-cell lung cancer with PD-L1 tumor proportion score < 50

CD24, a heavily glycosylated glycosylphosphatidylinositol–anchored surface protein, inhibits phagocytosis as potently as CD47. The relationship between such anti‐phagocytic factors and the immune response with immune–checkpoint inhibitors (ICI) remains unexplored. We evaluated CD24 and CD47 tumor proportion scores (TPS) in 68 of the 106 patients with advanced non–small‐cell lung cancer who participated in a prospective observational study of ICI treatment. We also explored the impact of CD24 TPS and CD47 TPS on ICI efficacy and serum cytokine changes. CD24 positivity (TPS ≥ 1) was negatively associated with progression–free survival (PFS) of ICI when PD‐L1 TPS was < 50 (median PFS; 37 vs 127 d, P = .033), but there was no association when PD‐L1 TPS was ≥ 50 (median PFS; 494 vs 144 d, P = .168). CD24 positivity was also related to significantly higher increase of CCL2 from baseline to 4‐6 wk later, and such increase was notably observed only when PD‐L1 TPS < 50 (P = .0004). CCL2 increase after ICI initiation was negatively predictive for survival after initiation of ICI (median survival time; not reached vs 233 d; P = .028). CD47 TPS high (≥60) significantly suppressed the increase in vascular endothelial growth factor (VEGF)‐A, D and PDGF‐AB/BB after ICI initiation. There was no association, however, between CD47 tumor expression and the efficacy of ICI. In conclusion, CD24, not CD47, is a candidate negative predictive marker of ICI in advanced, non–small‐cell lung cancer with PD‐L1 TPS < 50. Tumor expression of both CD24 and CD47 was associated with changes in factors related to monocytes and angiogenesis after ICI initiation (UMIN000024414).

Abstract 775: Longitudinal investigation of PD-L1 expression on circulating tumor cells (CTCs) in non-small cell lung cancer (NSCLC) patients treated with nivolumab

Purpose: We have previously reported that PD-L1-positive rate on CTCs at baseline was correlated with response to nivolumab in NSCLC patients. Here, we conducted a longitudinal follow-up investigation of PD-L1 expression on CTCs and its association with clinical outcome.

Methods: For CTC detection, 3ml of peripheral blood was collected from advanced NSCLC patients treated with nivolumab at baseline and week 4, 8, 12 and 24 or until progressive disease (PD). CTCs were enriched by microcavity array system based on the difference in size and defined as DAPI-positive, CK-positive, and CD45-negative cells and evaluated for PD-L1 expression by additional immunostaining.

Results: Forty-five patients were enrolled between January 2016 and January 2018 at Wakayama Medical University. The patient characteristics were as follows: median age 68 years (range, 49-86); male 75%; stage III/IV, 25/75%; adenocarcinoma/ squamous cell carcinoma/ other, 68/25/7%; partial response/stable disease/PD/not evaluable, 20/25/45/9%. At baseline, CTCs were evaluated in 44 patients (median, 13; range, 1-104) and PD-L1 positive CTCs were detected in 82% patients (median 29%; range, 0-100%), at week 4, evaluated in 31 patients (median, 4; range, 0-115) and detected in 58% patients (median, 13%; range, 0-100%), at week 8, evaluated in 16 patients (median, 11; range, 1-276) and detected in 56% patients (median, 7%; range, 0-60%), at week 12, evaluated in 13 patients (median, 11; range, 0-449) and detected in 62% patients (median, 15%; range, 0-88%), and at week 24, evaluated in 11 patients (median, 8; range, 0-35) and detected in 55% patients (median, 26%; range, 0-92%). Significant decrease in the ratio of PD-L1 positive CTCs between week 4 to week 8 was determined by Wilcoxon-matched-pairs signed rank test. Cutoff value of PD-L1-positivity rates in CTCs to segregate durable clinical benefit (DCB) from non-DCB was calculated to be 7% at week 8 according to ROC curve. Progression free survival was significantly longer in the patients with 7% or more of PD-L1 positivity rates (n = 8) than in those with less than 7% (n = 8) (p &lt; 0.01) at week 8, suggesting the predictive significance of early evaluation of PD-L1 expression on CTCs after nivolumab treatment. Interestingly, CTC count in 7 out of 9 patients who had a partial response (PR) transiently increased from the one immediately prior to achieving a PR. Progression free survival was significantly longer in patients with 1.5 times or more increase of CTC count (n = 6) than in those with less than 1.5 times (n = 3) (p &lt; 0.05), suggesting the transient tumor cell intravasation due to nivolumab treatment and its potential correlation with the duration of response depending on its magnitude.

Conclusions: Longitudinal evaluation of PD-L1-expressing CTCs may have a predictive potential in NSCLC patients treated with nivolumab.

Citation Format: Yasuhiro Koh, Mio Ikeda, Shunsuke Teraoka, Koichi Sato, Nahomi Tokudome, Atsushi Hayata, Hiroaki Akamatsu, Yuichi Ozawa, Keiichiro Akamatsu, Katsuya Endo, Masayuki Higuchi, Masanori Nakanishi, Hiroki Ueda, Nobuyuki Yamamoto. Longitudinal investigation of PD-L1 expression on circulating tumor cells (CTCs) in non-small cell lung cancer (NSCLC) patients treated with nivolumab [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 775.

Abstract B27: Longitudinal evaluation of PD-L1 expression on circulating tumor cells (CTCs) in non-small cell lung cancer (NSCLC) patients treated with nivolumab

Purpose: Though programmed death receptor-ligand 1 (PD-L1) expression on tumor tissue is a validated predictive biomarker for PD-1 pathway blockade in NSCLC, its longitudinal change during the treatment remains elusive. We have previously reported that PD-L1-positive rate on CTCs at baseline was correlated with response to nivolumab. Here, we conducted a longitudinal investigation of PD-L1 expression on CTCs in NSCLC patients treated with nivolumab and its association with clinical outcome.

Methods: For CTC detection, 3mL of peripheral blood was collected from advanced NSCLC patients treated with nivolumab at baseline and week 4, 8, 12, and 24 or until progressive disease (PD). The samples were enriched using the microcavity array system based on the difference in size. CTCs were defined as DAPI-positive, CK-positive, and CD45-negative cells and evaluated for PD-L1 expression by additional immunostaining.

Results: Forty-five patients were enrolled between January 2016 and January 2018 at Wakayama Medical University. The patient characteristics were as follows: median age 68 years (range, 49-86); male 75%; stage III/IV, 25/75%; adenocarcinoma/ squamous cell carcinoma/other, 68/25/7%; partial response/stable disease/PD/not evaluable, 20/25/45/9%. At baseline, CTCs were evaluated in 44 patients (median, 13; range, 1-104) and PD-L1 positive CTCs were detected in 82% of patients (median 29%; range, 0-100%); at week 4, evaluated in 31 patients (median, 4; range, 0-115) and detected in 58% of patients (median, 13%; range, 0-100%); at week 8, evaluated in 16 patients (median, 11; range, 1-276) and detected in 56% of patients (median, 7%; range, 0-60%); at week 12, evaluated in 13 patients (median, 11; range, 0-449) and detected in 62% of patients (median, 15%; range, 0-88%); and at week 24, evaluated in 11 patients (median, 8; range, 0-35) and detected in 55% of patients (median, 26%; range, 0-92%). Cutoff value of PD-L1-positivity rates in CTCs to segregate durable clinical benefit (DCB) from non-DCB was calculated to be 7% at week 8 according to receiver operating characteristic curve. Progression-free survival was significantly longer in the patients with less than 7% of PD-L1 positivity rates (n = 8) than in those with 7% or more (n = 8) (p &lt; 0.01) at week 8, suggesting the predictive significance of early evaluation of PD-L1 expression on CTCs after nivolumab treatment. It, however, did not translate into the predictive significance in overall survival. The change in CTC count at PD did not significantly differ between PD and last evaluation point before PD compared to that in non-PD patients at each evaluation point, suggesting the change in CTC count may not be predictive of disease progression upon nivolumab treatment.

Conclusion: Longitudinal evaluation of PD-L1-expressing CTCs may have a predictive potential in NSCLC patients treated with nivolumab. Evaluation in a larger cohort is warranted to confirm the results.

Citation Format: Mio Ikeda, Yasuhiro Koh, Shunsuke Teraoka, Koichi Sato, Nahomi Tokudome, Atsushi Hayata, Hiroaki Akamatsu, Yuichi Ozawa, Keiichiro Akamatsu, Katsuya Endo, Masayuki Higuchi, Masanori Nakanishi, Hiroki Ueda, Nobuyuki Yamamoto. Longitudinal evaluation of PD-L1 expression on circulating tumor cells (CTCs) in non-small cell lung cancer (NSCLC) patients treated with nivolumab [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr B27.

Differential significance of molecular subtypes which were classified into EGFR exon 19 deletion on the first line afatinib monotherapy

BACKGROUND

Epidermal growth factor receptor (EGFR)-sensitizing mutation, exon 19 deletion consists of several molecular variants. Influences of these variants on clinical response to EGFR tyrosine kinase inhibitors remain elusive.

METHODS

West Japan Oncology Group 8114LTR is a prospective, multi-institutional biomarker study. Treatment naïve, advanced non-small-cell lung cancer patients with EGFR-sensitizing mutation received afatinib monotherapy. We conducted a preplanned subset analysis of patients harboring exon 19 deletion. Tumor tissue exon 19 deletion molecular variants were identified by blocking-oligo-dependent polymerase chain reaction (PCR) and by Luminex Technology. Plasma cfDNA was also obtained before and after the treatment and EGFR mutations were detected with multiplexed, pico-droplet digital PCR assay.

RESULTS

Among 57 registered patients, twenty-nine patients were exon 19 deletion. Tissue DNA and cfDNA were available in 26 patients. Among the detected seven molecular variants, the most frequent was p.E746_A750delELREA (65.4%). According to the various classifications of molecular variants, twenty one (80.8%) were classified into 15-nucleotide deletion, one (3.8%) into 18-nucleotide deletion, and four patients (15.4%) into other insertion/substitution variant subgroups. The patient subgroup with 15-nucleotide deletion showed significantly longer progression-free survival than patients in other mixed insertion/substitution variant subgroup (p = 0.0244).

CONCLUSIONS

The clinical significance of molecular variants of exon 19 deletion on the first line afatinib monotherapy is reported here for the first time. Further investigation is needed for development of better therapeutic strategies.

TRIAL REGISTRATION

This trial was registered at UMIN Clinical Trials Registry at 2014/12/4 (UMIN000015847).

Detection of AXL expression in circulating tumor cells of lung cancer patients using an automated microcavity array system

Noninvasive diagnostics using circulating tumor cells (CTCs) are expected to be useful for decision making in precision cancer therapy. AXL, a receptor tyrosine kinase is associated with tumor progression, epithelial‐to‐mesenchymal transition (EMT), and drug resistance, and is a potential therapeutic target. However, the epithelial markers generally used for CTC detection may be not enough to detect AXL‐expressing CTCs due to EMT. Here, we evaluated the detection of AXL‐expressing CTCs using the mesenchymal marker vimentin with a microcavity array system. To evaluate the recovery of cancer cells, spike‐in experiments were performed using cell lines with varying cytokeratin (CK) or vimentin (VM) expression levels. With high CK and low VM‐expressing cell lines, PC‐9 and HCC827, the recovery rate of AXL‐expressing cancer cells was 1%‐17% using either CK or VM as markers. Whereas, with low CK and high VM‐expressing cell lines, MDA‐MB231 and H1299, it was 52%‐75% using CK and 72%‐88% using VM as a marker. For clinical evaluation, peripheral blood was collected from 20 non–small cell lung cancer patients and CTCs were detected using CK or VM as markers in parallel. Significantly more AXL‐expressing single CTCs were detected in VM‐positive than CK‐positive CTCs (P < .001). Furthermore, CTC clusters were identified only among VM‐positive CTCs in 20% of patients. Patients with one or more prior treatments harbored significantly more VM‐positive AXL‐expressing CTCs, suggesting the involvement of these CTCs in drug resistance. These results indicate the necessity of integrating mesenchymal markers with CTC detection and this should be further evaluated clinically.

Immune-Related Adverse Events by Immune Checkpoint Inhibitors Significantly Predict Durable Efficacy Even in Responders with Advanced Non-Small Cell Lung Cancer

Background

Although predictive value of immune‐related adverse events (irAEs) induced by immune checkpoint inhibitors (ICIs) have been suggested by several studies, their assessments were insufficient because patients were categorized only by the occurrence of irAEs. It has not been elucidated whether irAEs also play a significant role even in responders.

Materials and Methods

Between December 2015 and September 2018, 106 patients with advanced non‐small cell lung cancer treated with ICIs were enrolled in our prospective biomarker study. Twenty‐three of these were responders, defined as those with complete or partial response. We investigated the proportion of irAEs among overall and responders. For responders, progression‐free survival (PFS) and overall survival of ICIs were compared between those with and without irAEs. As an exploratory analysis, we measured 41 proteins from peripheral blood before and after ICI treatment.

Results

The proportion of irAEs was significantly higher in responders than nonresponders (65.2% vs. 19.3%, p < .01). Among responders, clinical characteristics did not differ regardless of the occurrence of irAEs. However, there was a significant difference in PFS among responders (irAE group 19.1 months vs. non‐irAE group 5.6 months; hazard ratio: 0.30 [95% confidence interval: 0.10–0.85]; p = .02). Of 41 protein analyses, fibroblast growth factor‐2 at baseline and monocyte chemoattractant protein fold change showed significant differences between them (p < .04).

Conclusion

Although this is a small sample–sized study, irAE might be a predictive factor of durable efficacy, even in patients who responded to ICIs. Investigation into the significance of irAEs in responders will contribute to the establishment of optimal administration of ICI.

Implications for Practice

Although the predictive value of immune‐related adverse events (irAEs) induced by immune checkpoint inhibitors (ICIs) has been suggested by several studies, it has not been elucidated whether irAEs also play a significant role even in responders. This study showed that more than 60% of responders had irAEs. It demonstrated the strong correlation between irAEs and efficacy even in responders. Investigation into the significance of irAEs in responders will contribute to the establishment of optimal administration of ICI.

Immune‐related adverse events might be a predictive factor of efficacy, even I patients who respond to immune checkpoint inhibitor therapy. This study investigated the significance of immune‐related adverse events in patients with non‐small cell lung cancer who had complete or partial response after treatment with immune checkpoint inhibitors.

Abstract 414: Detection of AXL-expressing circulating tumor cells (CTCs) in non-small-cell lung cancer (NSCLC) patients using an automated microcavity array (MCA) system

Purpose: Noninvasive diagnostics has been developed over the last decade and we have previously reported that CTCs can be utilized for evaluating molecular features of NSCLC. AXL, a receptor tyrosine kinase is linked to epithelial-to-mesenchymal transition (EMT) leading to cancer progression and regarded as a potential therapeutic target. However, many of current technologies rely on epithelial markers to detect CTCs and that makes it difficult to detect AXL-expressing CTCs. Here, we established the detection of AXL expression on CTCs using MCA system.

Methods: Preclinical experiments were performed using NSCLC cell lines H1299, PC9, and HCC827 and a breast cancer cell line MDA-MB231 with varying cytokeratin (CK) and AXL expression levels. The cells were spiked into 3 ml of peripheral blood from healthy donors, then enriched using MCA system, and detected by staining for CD45, DAPI, CK or vimentin (VM) with the addition staining for AXL. For clinical evaluation, 3ml of peripheral blood was collected from advanced NSCLC patients.

Results: DAPI-positive, CK or VM-positive, and CD45-negative cells were defined as CTCs. In spike-in experiments, when CK was used as a marker, AXL expression was detected in 5 and 17% of high CK-expressing HCC827 and PC9 cells, respectively and detected in 52 and 75% of low CK-expressing H1299 and MDA-MB231 cells, respectively. On the other hand, when VM was used as a marker, AXL expression was detected in 72 and 88% of high VM-expressing MDA-MB231 and H1299 cells, respectively whereas detected in 1 and 7% of PC9 and HCC827 cells with low VM expression, respectively. Twenty-four patients were enrolled in the clinical study. The patient characteristics were as follows: median age 69.5 years (range, 49-84); male 88%; stage III/IV, 25/75%; adenocarcinoma/ squamous cell carcinoma/ other, 63/33/4%. Both CK and VM staining in 17 patients, only CK in 6 patients, and only VM in 1 patient were performed. CK-positive single CTCs were detected in all patients (median, 4; range, 1-50) and AXL-expressing CK-positive single CTCs were detected in 26% of patients (median, 0; range, 0-1). On the other hand, VM-positive single CTCs were detected in 94% of patients (median, 6.5; range, 0-128) and AXL-expressing VM-positive single CTCs were detected in 89% of patients (median, 1; range, 0-106). Significantly more AXL-expressing single CTCs were detected in VM-positive than CK-positive (p &lt; 0.001). Notably, all of identified CTC clusters were positive for only VM, not CK and AXL-expressing CTC clusters were detected in 33% of patients (median, 0; range, 0-22).

Conclusion: Our data indicate that incorporating VM staining is necessary to detect AXL-positive CTCs due to EMT. Further clinical evaluation is warranted for validating the method and the clinical significance of AXL-positive CTCs.

Citation Format: Mio Ikeda, Yasuhiro Koh, Shunsuke Teraoka, Jun Oyanagi, Kuninobu Kanai, Atsushi Hayata, Nahomi Tokudome, Hiroaki Akamatsu, Yuichi Ozawa, Keiichiro Akamatsu, Masayuki Higuchi, Masanori Nakanishi, Hiroki Ueda, Nobuyuki Yamamoto. Detection of AXL-expressing circulating tumor cells (CTCs) in non-small-cell lung cancer (NSCLC) patients using an automated microcavity array (MCA) system [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 414.

Abstract 416: Predictive significance of serum protein levels in advanced non-small-cell lung cancer patients treated with pembrolizumab

Background: We have previously reported that serum IL-8 and G-CSF were correlated with clinical benefit and immune-related adverse events (irAE), respectively in non-small-cell lung cancer (NSCLC) patients treated with nivolumab. Here, we measured multiple serum proteins serially in NSCLC patients treated with pembrolizumab and explored the potential of predicting clinical response or irAE onset. This study was registered at UMIN (ID: 000024414).

Patients and Methods: Advanced NSCLC patients received pembrolizumab monotherapy (200 mg/body, q3W) until progressive disease (PD) or unacceptable toxicity. Serum samples were collected at baseline and at week 6. Best response was classified into partial response (PR), stable disease (SD), or progressive disease (PD) according to RECIST v1.1. Using LuminexTM xMapTM technology, serum levels of 41 proteins consisting of cytokines, chemokines, growth factors, and angiogenesis factors were measured. All statistical analyses were carried out using JMP Pro software (ver. 13.0) and Mann-Whitney U test were performed accordingly. A p value &lt;0.05 was considered as significant.

Results: Thirty-seven patients were registered in the study between March 2017 and October 2018 at Wakayama Medical University Hospital and 32 were included in the final analysis. Demographics of the patients were as follows: median age 70 (range, 50 to 91); male 75%; smoker 88%; stage III/IV, 22/78%; squamous/non-squamous, 31/69%, previous treatment; 0/1≤, 47/53%. Objective response rate was 28% and disease control rate was 56% in the entire cohort and 40% and 67%, respectively in the first-line subset. Among 41 serum proteins measured, no serum protein at baseline was associated with efficacy or irAE onset in the entire cohort. Levels of serum VEGF-C and sCD40L at baseline, however, in the first-line subset were found significantly lower in the patient who had PR and SD than those who did not. RANTES was also found significantly lower in patients who had PR in the 2nd or later line subset. With regard to irAE prediction, changes of HB-EGF levels between baseline and week 6 were significantly smaller in irAE patients in the entire cohort and changes of MCP-1 levels were significantly smaller in irAE patients in second or later line subset. The serum proteins identified in the current study were not overlapped with those identified in advanced NSCLC patients treated with nivolumab in the previous study.

Conclusions: We identified potential serum protein markers associated with clinical benefit and irAE from pembrolizumab treatment in advanced NSCLC by multi-analyte protein-based assay. Our results suggest that serum proteins associated with efficacy and irAE may vary among different anti-PD-1 antibodies and also between in the first-line setting and later one.

Citation Format: Jun Oyanagi, Yasuhiro Koh, Shunsuke Teraoka, Kuninobu Kanai, Atsuhsi Hayata, Nahomi Tokudome, Hiroaki Akamatsu, Yuichi Ozawa, Keiichiro Akamatsu, Masanori Nakanishi, Hiroki Ueda, Nobuyuki Yamamoto. Predictive significance of serum protein levels in advanced non-small-cell lung cancer patients treated with pembrolizumab [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 416.

Heterogeneous Expression of Programmed Death Receptor-ligand 1 on Circulating Tumor Cells in Patients With Lung Cancer

BACKGROUND

Blockade of the programmed death receptor-1 (PD-1) pathway is effective against solid tumors including lung cancer. PD-ligand 1 (PD-L1) expression on tumor tissue serves as a predictive biomarker for the efficacy of PD-1 pathway blockade. Here, we evaluated the expression of PD-L1 on circulating tumor cells (CTCs) in patients with lung cancer.

MATERIALS AND METHODS

Peripheral whole blood (3 mL) was collected from patients, and CTCs and PD-L1 expression were detected using a microcavity array (MCA) system. Immunohistochemistry for PD-L1 detection was also performed using matched tumor tissues.

RESULTS

Sixty-seven patients with lung cancer were enrolled in the study between July 2015 and April 2016 at Wakayama Medical University Hospital. The characteristics of the patients were as follows: median age, 71 years (range, 39-86 years); male, 72%; stage II to III/IV, 14%/85%; non-small-cell lung cancer/small-cell lung cancer/other, 73%/21%/6%. CTCs were detected in 66 of 67 patients (median, 19; range, 0-115), and more than 5 CTCs were detected in 78% of patients. PD-L1-expressing CTCs were detected in 73% of patients, and the proportion score of PD-L1-expressing CTCs ranged from 3% to 100%, suggesting intra-patient heterogeneity of PD-L1 expression on CTCs. Tumor tissues were available from 27 patients and were immunostained for PD-L1, and no correlation was observed between tumor tissues and CTCs based on the proportion score (R² = 0.0103).

CONCLUSION

PD-L1 expression was detectable on CTCs in patients with lung cancer, and intra-patient heterogeneity was observed. No correlation was observed between PD-L1 expression in tumor tissues and CTCs.

Predictive value of serum protein levels in patients with advanced non-small cell lung cancer treated with nivolumab

BACKGROUND

Although programmed cell death-ligand-1 (PD-L1) expression in tumor tissue has been established as predictive biomarker for the anti-programmed cell death-1 (PD-1) antibody treatment of non-small-cell lung cancer (NSCLC), additional biomarkers are critically needed. We evaluated serum proteins relevant to immune checkpoint blockade in patients with NSCLC treated with nivolumab to identify novel non-invasive predictive biomarkers.

PATIENTS AND METHODS

Patients with advanced NSCLC, who had failed at least one prior chemotherapy regimen, received nivolumab monotherapy (3 mg/kg, Q2W) until progressive disease (PD) or unacceptable toxicity was observed. Blood samples were collected at baseline and week 4. Fifty-seven serum protein levels were quantified with a Milliplex MAP assay. The associations of both clinical benefit (CB) and the onset of immune related adverse events (irAEs) with serum proteins levels were evaluated.

RESULTS

Thirty-eight patients with advanced NSCLC were enrolled in the study, with 38 and 32 paired serum samples at baseline and week 4 being available for efficacy analysis and irAE analysis, respectively. In durable CB (DCB) patients compared with non-DCB patients, the baseline serum levels of BMP-9 were significantly higher, whereas the follistatin, IL-8, IP-10, and TNF-α levels were significantly lower. In irAE patients compared with non-irAE patients the serum levels of G-CSF and RANTES at week 4 were significantly higher, whereas the levels of leptin were significantly lower. A multivariate analysis revealed that follistatin and IP-10 were statistically associated with DCB (p < 0.05) and RANTES was associated with irAE onset (p < 0.05). In a subset of irAE-developed patients, RANTES levels decreased after steroid administration, supporting its involvement in irAE.

CONCLUSION

Serum proteins have the potential to be predictive markers for DCB and irAEs onset in patients with NSCLC treated with nivolumab. In addition, antitumor activity and irAEs may not be regulated by the same mechanisms.

Abstract 2608: Predictive values of serum protein levels in advanced non-small cell lung cancer patients treated with nivolumab

Background: Though PD-ligand 1 (PD-L1) expression on tumor tissue has been established as companion diagnostics in non-small-cell lung cancer (NSCLC) for anti-PD-L1 treatment, additional biomarkers to enrich the patients likely to benefit from the therapy are critically needed. Here, we conducted a serial evaluation of multiple serum proteins relevant to the modulation of immune system in NSCLC patients treated with nivolumab.

Patients and Methods: Advanced NSCLC patients after failure of at least one prior chemotherapy regimen received nivolumab monotherapy (3mg/kg, q2W) until progressive disease (PD) or unacceptable toxicity. Serum samples were collected at baseline and at week 4. Best response was classified into partial response (PR), stable disease (SD), or progressive disease (PD) according to RECIST v1.1. Using LuminexTM xMapTM technology, serum levels of 54 proteins consisting of cytokines, chemokines, growth factors, and angiogenesis factors were measured. All statistical analyses were carried out using JMP Pro software (ver. 13.0) and Mann-Whitney U test and Spearman's test were performed accordingly. A p value &lt;0.05 was considered as significant.

Results: Thirty-eight patients were registered in the study between January 2016 and March 2017 at Wakayama Medical University Hospital and 34 were included in the final analysis. Demographics of the patients were as follows: median age 68 (range, 49 to 86); male 73 %; stage IV, 100 %; squamous/non-squamous, 30/70 %. Overall response rate was 22% (7/34), and disease control rate was 53% (18/34). Among 54 serum proteins measured serially, the level of serum TNF-α was significantly lower at baseline in non-PD patients than PD patients (p &lt; 0.05). The level of TNF-α was also correlated with longer progression free survival (PFS) (r= -0.5693). Serum IL-8 level at week 4 in PR patients were significantly lower than those in non-PR patients (p &lt;0.01) though no difference was observed at baseline between the two, supporting the relevance of serum IL-8 level to the efficacy of nivolumab. Correlation between IL-8 levels at week 4 and longer PFS turned out to be more significant (r=-0.6864). In addition, serum levels of VEGF-A, TGF-β1 and PDGF-AB/BB were significantly lower in PR patients than those in non-PR patients at week 4 (p &lt;0.05). However, these protein levels were not correlated with PFS.

Conclusions: We identified that the serum levels of IL-8, TNF-α, VEGF-A, TGF-β1 and PDGF-AB/BB as potential biomarkers to predict clinical benefit from nivolumab treatment in advanced NSCLC by multi-analyte protein-based assay. Incorporating additional serum protein levels may have potential to improve the patient enrichment besides previously reported potential biomarkers such as IL-8 and VEGF levels. Further evaluation is warranted in a larger cohort to validate the findings.

Citation Format: Jun Oyanagi, Yasuhiro Koh, Hiroaki Akamatsu, Kuninobu Kanai, Atsushi Hayata, Nahomi Tokudome, Keiichiro Akamatsu, Keiichiro Akamatsu, Masanori Nakanishi, Hiroki Ueda, Nobuyuki Yamamoto. Predictive values of serum protein levels in advanced non-small cell lung cancer patients treated with nivolumab [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2608.

Abstract 5595: Predictive impact of sequential evaluation of PD-L1-expressing circulating tumor cells in NSCLC patients treated with nivolumab

Background: Anti-PD-1 antibody nivolumab has become a new standard treatment for pretreated, advanced non-small cell lung cancer (NSCLC). Although PD-L1 expression on tumor tissue has a predictive value, significance of its expression on circulating tumor cells (CTCs) is unknown. Here, we conducted a sequential evaluation of PD-1-expressing CTCs in NSCLC patients treated with nivolumab.

Methods: Advanced NSCLC patients who received nivolumab at Wakayama Medical University Hospital were enrolled in the study (UMIN000024414). Nivolumab was administered 3 mg/kg bi-weekly until progressive disease (PD) or unacceptable toxicity. Peripheral whole blood (3 mL) was collected in an EDTA collection tube (BD vacutainer) and processed within 3 hours for CTC evaluation at baseline, week 4 and week 8. CTCs were detected using automated microcavity array system (Hitachi Chemical Co.). PD-L1 expression was immunohistochemically examined on both tumor tissues and CTCs using anti-PD-L1 antibody, clone 28-8 (Abcam).

Results: Thirty-eight patients were registered in the study between January 2016 and September 2016. Clinical characteristics of the patients were as follows: median age 68 (range, 49 to 86); male 73 %; stage IV 100 %; squamous/non-squamous, 30/65 %. Regarding nivolumab treatment, overall response rate (ORR) was 22% (95% confidence interval [CI]: 10-38%), and median progression-free survival (PFS) was 62 days (95%CI: 40-235 days). At baseline, CTCs were detected in all patients (median, 15; range, 1-90) and PD-L1-expressing CTCs were detected in 87% of patients. Tumor proportion score (TPS) of PD-L1 expression on CTCs varied from 6% to 100%. Matched tumor tissues were available from 14 patients and 7 showed the PD-L1 TPS ≥50%. PD-L1 status on CTCs was not correlated with that on tumor tissues both using proportional score and H score (Spearman's correlation: r = 0.0007 and 0.08, respectively). On CTCs, patients with PD-L1 ≥50 % have significantly higher disease control rate than those with below 50% (83.3% versus 36.4%, p&lt;0.01). Similarly, patients with PD-L1 ≥50 % on CTC had significantly longer PFS compared with those with below 50% (293 days versus 49 days, hazard ratio 2.41 (95% CI: 1.05-5.54), p = 0.03). During nivolumab treatment, number of CTCs was decreased (median number was 10 at 4 weeks, and 5 at 8 weeks). Among those with PD-L1 ≥50 % on CTC at baseline, changes in number and PD-L1 status on CTCs at 4 weeks did not correlate with PFS.

Conclusions: Sequential monitoring of PD-L1 expression on CTCs during nivolumab treatment was successfully conducted. PD-L1 expression on CTCs at baseline was a strong predictor in efficacy. Predictive significance of PD-L1-positive CTCs should be evaluated in a larger validation cohort.

Citation Format: Yasuhiro Koh, Hiroaki Akamatsu, Keita Mori, Kuninobu Kanai, Atsushi Hayata, Nahomi Tokudome, Masayuki Higuchi, Keiichiro Akamatsu, Masanori Nakanishi, Hiroki Ueda, Nobuyuki Yamamoto. Predictive impact of sequential evaluation of PD-L1-expressing circulating tumor cells in NSCLC patients treated with nivolumab [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5595.

Comprehensive Mutation and Copy Number Profiling in Archived Circulating Breast Cancer Tumor Cells Documents Heterogeneous Resistance Mechanisms

Addressing drug resistance is a core challenge in cancer research, but the degree of heterogeneity in resistance mechanisms in cancer is unclear. In this study, we conducted next-generation sequencing (NGS) of circulating tumor cells (CTC) from patients with advanced cancer to assess mechanisms of resistance to targeted therapy and reveal opportunities for precision medicine. Comparison of the genomic landscapes of CTCs and tissue metastases is complicated by challenges in comprehensive CTC genomic profiling and paired tissue acquisition, particularly in patients who progress after targeted therapy. Thus, we assessed by NGS somatic mutations and copy number alterations (CNA) in archived CTCs isolated from patients with metastatic breast cancer who were enrolled in concurrent clinical trials that collected and analyzed CTCs and metastatic tissues. In 76 individual and pooled informative CTCs from 12 patients, we observed 85% concordance in at least one or more prioritized somatic mutations and CNA between paired CTCs and tissue metastases. Potentially actionable genomic alterations were identified in tissue but not CTCs, and vice versa. CTC profiling identified diverse intra- and interpatient molecular mechanisms of endocrine therapy resistance, including loss of heterozygosity in individual CTCs. For example, in one patient, we observed CTCs that were either wild type for ESR1 (n = 5/32), harbored the known activating ESR1 p.Y537S mutation (n = 26/32), or harbored a novel ESR1 p.A569S (n = 1/32). ESR1 p.A569S was modestly activating in vitro, consistent with its presence as a minority circulating subclone. Our results demonstrate the feasibility and potential clinical utility of comprehensive profiling of archived fixed CTCs. Tissue and CTC genomic assessment are complementary, and precise combination therapies will likely be required for effective targeting in advanced breast cancer patients.Significance: These findings demonstrate the complementary nature of genomic profiling from paired tissue metastasis and circulating tumor cells from patients with metastatic breast cancer. Cancer Res; 78(4); 1110-22. ©2017 AACR.

Intermittent Capecitabine Monotherapy with Lower Dose Intensity in Heavily Pretreated Patients with Metastatic Breast Cancer

Aims and Background

The purpose of the present retrospective study was to evaluate efficacy and safety of a lower dose-intensity capecitabine monotherapy regimen in heavily pretreated patients with metastatic breast cancer.

Methods

Patients with metastatic breast cancer who had been administered capecitabine monotherapy between June 2003 and August 2004 at our hospital were retrospectively reviewed. Oral capecitabine (828 mg/m2) was given twice daily for three weeks followed by a one-week rest period; this was repeated every four weeks.

Results

One-hundred and two patients were assessed. Median follow-up of patients was 16.4 months. One hundred patients (98%) had been pretreated with either anthracyclines or taxanes, 81 patients (79%) with both anthracyclines and taxanes. Response rate was 17% (95% CI, 9-24%), and clinical benefit rate was 41% (95% CI, 32-51%). Median time-to-treatment failure was 4.9 months, and median overall survival time was 24.3 months. This regimen was well tolerated. The most frequent grade 3 or 4 adverse event was hand-foot syndrome (6%). Other grade 3 or 4 adverse events were seen in only 1%-3% of patients.

Conclusions

Intermittent capecitabine monotherapy with lower dose intensity achieved a high tumor control rate with low toxicity in heavily pretreated metastatic breast cancer patients.

Abstract A056: Sequential tracking of PD-L1 expression on circulating tumor cells in NSCLC patients treated with nivolumab

Background: Nivolumab (anti-PD-1 antibody) has become a new standard treatment in pretreated, advanced non-small cell lung cancer (NSCLC). Although strong expression of PD-L1 on tumor tissue has predictive value, significance of its expression on circulating tumor cell (CTC) is unknown and its status can be changed during the treatment. Here, we conducted a serial evaluation of PD-1-expressing CTCs in NSCLC patients treated with nivolumab. Methods: Advanced NSCLC patients who receive nivolumab at Wakayama Medical University Hospital were enrolled in this prospective observational study (registered at UMIN (000024414)). Nivolumab was administered 3 mg/kg biweekly until progressive disease (PD) or unacceptable toxicity. Peripheral whole blood (3 mL) was collected in a EDTA collection tube (BD vacutainer) and processed within 3 hours for CTC evaluation at baseline, week 4, and week 8. CTCs were detected using microcavity array system (Hitachi Chemical Co.). PD-L1 expression was immunohistochemically examined on both tumor tissues and CTCs using anti-PD-L1 antibody, clone 28-8 (Abcam). Results: Thirty-eight patients were registered in this study between January 2016 and September 2016. Clinical characteristics of the patients were as follows: median age 68 (range, 49 to 86); male 73%; stage IV 100%; squamous/non-squamous, 30/65%. Regarding nivolumab treatment, overall response rate (ORR) was 22% (95% confidence interval (CI): 10-38%), and median progression-free survival (PFS) was 62 days (95%CI: 40-235 days). At baseline, CTCs were detected in all patients (median, 15; range, 1-90) and PD-L1-expressing CTCs were detected in 87% of patients. Tumor proportion score (TPS) of PD-L1 expression on CTCs varied from 6% to 100%. Matched tumor tissues were available from 14 patients and 7 showed the PD-L1 TPS ≥ 50%. PD-L1 status on CTCs was not correlated with that on tumor tissues both using proportional score and H score (Spearman’s correlation: r = 0.0007 and 0.08, respectively). On CTCs, patients with PD-L1 ≥ 50 have significantly higher disease control rate than those with below 50% (83.3% versus 36.4%, p&lt;0.01). Similarly, patients with PD-L1 ≥ 50% on CTC was significantly longer PFS compared with those with below 50% (293 days versus 49 days, hazard ratio 2.41 (95% CI: 1.05-5.54), p = 0.03). During nivolumab treatment, number of CTCs was decreased (median number was 10 at 4 weeks and 5 at 8 weeks). Among those with PD-L1 ≥ 50% on CTC at baseline, changes in number and PD-L1 status on CTCs at 4 weeks did not correlate with PFS. Conclusions: Serial monitoring of PD-L1 expression on CTCs during nivolumab treatment was successfully conducted. PD-L1 expression on CTCs at baseline was a strong predictor in efficacy. Predictive significance of PD-L1-positive CTCs should be also evaluated in validation cohort using pembrolizumab.

Citation Format: Hiroaki Akamatsu, Yasuhiro Koh, Keita Mori, Kuninobu Kanai, Atsushi Hayata, Nahomi Tokudome, Masayuki Higuchi, HIsashige Kanbara, Keiichiro Akamatsu, Masanori Nakanishi, Hiroki Ueda, Nobuyuki Yamamoto. Sequential tracking of PD-L1 expression on circulating tumor cells in NSCLC patients treated with nivolumab [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A056.

Abstract A057: Serial evaluation of multiple serum protein levels in non-small lung cancer patients treated with nivolumab

Background: Blockade of programmed death receptor-1 (PD-1) pathway is effective against various malignancies. Although PD-ligand 1 (PD-L1) expression on tumor tissue has been established as companion diagnostics in non-small cell lung cancer (NSCLC), additional biomarkers to enrich the patients likely to benefit from the therapy are critically needed. Here, we conducted a serial evaluation of multiple serum cytokines, growth factors, and angiogenesis factors relevant to immune checkpoint blockade in NSCLC patients treated with nivolumab. Patients and Methods: Advanced NSCLC patients after failure of at least one prior chemotherapy regimen received nivolumab monotherapy (3mg/kg, q2W) until progressive disease (PD) or unacceptable toxicity. Serum samples were collected in a serum separation tube (Venoject II autosep, TERUMO) at baseline and at week 4. Best response was classified into partial response (PR), stable disease (SD), or progressive disease (PD) according to RECIST v1.1. Using LuminexTM xMapTM technology, serum levels of 54 proteins consisting of cytokines, chemokines, growth factors, and angiogenesis factors were analyzed. All statistical analyses were carried out using JMP Pro software (ver. 13.0) and Mann-Whitney U test and Spearman's test were performed accordingly. A p value &lt;0.05 was considered as significant. Results: Thirty-eight patients were registered in the study between January 2016 and March 2017 at Wakayama Medical University Hospital and 34 were included in the analysis. Demographics of the patients were as follows: median age 68 (range, 49 to 86); male 73 %; stage IV, 100%; squamous/non-squamous, 30/70 %. Overall response rate was 22% (7/34), and disease control rate was 53% (18/34). Among 54 serum proteins measured serially, the levels of serum IL-8 and TNF-α were significantly lower at baseline in non-PD patients than in PD patients (p &lt; 0.01 in both cases). In addition, the levels of both serum IL-8 and TNF-α were correlated with longer progression-free survival (PFS) (r=-0.4695 and -0.5912, respectively). It is noteworthy that serum IL-8 levels at week 4 in PR patients were significantly lower than those in non-PR patients (p &lt;0.01). Correlation between IL-8 levels at week 4 and longer PFS was shown to be more significant (r=-0.6864). Serum VEGF-A levels were significantly lower in PR patients than those in non-PR patients at week 4 (p &lt;0.05). Conclusions: We identified the serum levels of IL-8, TNF-α, and VEGF-A as potential biomarkers to predict clinical benefit from nivolumab treatment in advanced NSCLC by multi-analyte protein-based assay. Incorporating serum TNF-α levels may have potential to improve the patient enrichment in addition to previously reported potential biomarkers such as IL-8 and VEGF levels. Further evaluation is warranted in a larger cohort to validate the findings.

Citation Format: Jun Oyanagi, Yasuhiro Koh, Hiroaki Akamatsu, Kuninobu Kanai, Atsushi Hayata, Nahomi Tokudome, keiichiro Akamatsu, Masanori Nakanishi, Hiroki Ueda, Nobuyuki Yamamoto. Serial evaluation of multiple serum protein levels in non-small lung cancer patients treated with nivolumab [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A057.

Abstract 3797: Non-invasive identification of tumor cells using near infrared composition imaging system

BACKGROUND: Circulating tumor cells (CTCs) are expected to be utilized for decision-making in precision cancer medicine and further elucidation of cancer biology. However, it remains challenging to detect and isolate CTCs without any damages, that is critically important to analyze the molecular and biological properties of CTCs. Near infrared (NIR) imaging is one of the emerging technologies in the medical field and expected to be applied to visualization of blood vessels, nerves, and muscles under the skin or mucosa. Here we attempted to apply the NIR imaging technologies to distinguishing tumor cells from normal blood cells.

METHODS: To obtain NIR images, real-time composition imaging system Compovision® (Sumitomo Electric Industries, Ltd.) was used. This system is equipped with an NIR spectrographic camera and this camera processes hyperspectral data, in which each pixel has spectral data instead of a visible image in the wavelength band of 1,000-2,350 nm. The X-axis and Y-axis of the sensor chip correspond to the spatial direction and wavelength. Thus, hyperspectral data stores both image and spectral information. For this feasibility study, lung cancer cell lines with varying EpCAM expression levels such as A549, PC-9, PC-14, H23 were used. Lymphocytes and red blood cells were obtained from the peripheral blood of healthy volunteers. Phosphate-buffered saline (PBS) was used as a negative control. After we obtained NIR hyperspectral data, multivariate analysis such as principal component analysis (PCA) was performed for precise analysis.

RESULTS: We were able to obtain the hyperspectral data from all the lung cancer cell lines, lymphocytes, red blood cells and PBS alone and the spatially averaged spectrum was extracted from each data. Then the spectra were converted to absorption spectra and analyzed by PCA using the Unscrambler® X (CAMO Software) in the wavelength range of 1,000-2,200 nm. Two principal components were selected from results to separate data. Two-dimensional PCA score plot showed the clear segregation between tumor cells and normal blood cells such as lymphocytes and red blood cells, indicating the potential of non-invasive detection of tumor cells. In addition, obtained spectra from both EpCAM-expressing and EpCAM-non-expressing tumor cells were successfully segregated from those from normal blood cells. According to these results, it is suggested that segregating cells based on the difference in cytoskeletal components between epithelial cells and blood cells is feasible using the NIR imaging technology.

CONCLUSIONS: Using the NIR composition imaging technology, we were able to obtain the different spectral characteristics between tumor cells and normal blood cells, suggesting that this technology holds the potential to detect and isolate CTCs without any invasive labeling. This should be further explored for its application to the identification of CTCs.

Citation Format: Yasuhiro Koh, Satoshi Kambayashi, Hiroaki Akamatsu, Nahomi Tokudome, Hiroki Ueda, Nobuyuki Yamamoto. Non-invasive identification of tumor cells using near infrared composition imaging system [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 3797. doi:10.1158/1538-7445.AM2017-3797

Abstract 3778: PD-L1 expression on circulating tumor cells and its comparison with tumor tissues in Japanese lung cancer patients

Background: Blockade of programmed death receptor-1 (PD-1) pathway is effective against solid tumors including lung cancer. Although PD-ligand 1 (PD-L1) expression on tumor tissue is expected as a potent predictive biomarker, its detection remains challenging due to its dynamic and unstable status. Circulating tumor cells (CTCs) have potential as an alternative material for non-invasive and real-time diagnosis. Here, we evaluated the PD-L1 expression on CTCs in patients with lung cancer and investigated the agreement between tumor tissues and CTCs.

Material and methods: CTCs were captured and immune-stained using microcavity array system. CTCs were defined as those positive for DAPI and cytokeratin (CK) and negative for CD45. PD-L1 expression on CTCs was evaluated by addition of the process of PD-L1 immunocytochemistry. For CTCs detection, 3 ml of peripheral whole blood was collected from the patients who consented in written form and PD-L1 immunohistochemistry was performed using corresponding tumor tissues.

Results: Sixty-seven lung cancer patients were enrolled in the study between July 2015 and April 2016 at Wakayama Medical University. Patient characteristics were as follows: median age 71 (range, 39 to 86); male 72%; stage II-III/IV, 15/85%; non-small cell lung cancer (NSCLC)/small cell lung cancer (SCLC)/Other, 73/21/6%. CTCs were detected in 66 out of 67 patients (median 19; range, 0 to 115) and more than 5 CTCs were detected in 78% of patients. PD-L1-expressing CTCs were detected in 73% of patients and the proportion score (PS) of PD-L1-expressing CTCs ranged from 3% to 100%, suggesting intra-patient heterogeneity of PD-L1 expression on CTCs. Significantly more PD-L1-expressing CTCs were detected in patients without EGFR mutations than those with EGFR mutations (P = 0.0433). Tumor tissues were available from 28 patients and were immune-stained for PD-L1. Seven showed the PS of PD-L1-expressing tumor cells &lt; 1%, 11 showed 1-49%, and 10 showed ≥ 50%. No positive correlation was observed on PD-L1 expression between tumor tissues and CTCs based on PS (R2 = 0.0034). Three adenocarcinoma cases with PD-L1-positive tumor tissue did not harbor any PD-L1-expressing CTCs and conversely, three adenocarcinoma cases with PD-L1-negative tumor tissue harbored PD-L1-expressing CTCs, showing the discrepancy between tumor tissues and CTCs. It is also noteworthy that SCLC patients had perfect agreement on PD-L1 expression between tumor tissues and CTCs.

Conclusions: PD-L1 expression was detectable on CTCs in lung cancer patients and intra-patient heterogeneity of its expression was observed. There was no agreement between tumor tissues and CTCs on PD-1 expression. Further investigation is warranted to better understand the clinical significance of PD-L1-expressing CTCs.

Citation Format: Hiroaki Akamatsu, Yasuhiro Koh, Satomi Yagi, Satoshi Kambayashi, Ayaka Tanaka, Kuninobu Kanai, Atsushi Hayata, Nahomi Tokudome, Keiichiro Akamatsu, Masayuki Higuchi, Hisashige Kanbara, Masanori Nakanishi, Hiroki Ueda, Nobuyuki Yamamoto. PD-L1 expression on circulating tumor cells and its comparison with tumor tissues in Japanese lung cancer patients [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 3778. doi:10.1158/1538-7445.AM2017-3778

Abstract 4149: Increased migration ability of osimertinib-resistant EGFR-T790M mutant non-small-cell lung cancer cells

Background: A third generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) osimertinib is effective against gefitinib/erlotinib-resistant non-small-cell lung cancer (NSCLC) harboring EGFR T790M mutation. Although the majority of these patients initially responds to osimertinib, they eventually develop resistance. Acquired mutations such as EGFR C797S mutation have been reported to confer resistance to osimertinib, but mechanisms of resistance to osimertinib or biological behaviors of osimertinib-resistant NSCLC have not been fully elucidated.

Materials and methods: Osimertinib-resistant PC-9/ZD/OR1 and PC-9/ZD/OR3 cells were generated after continuous exposure of gefitinib-resistant PC-9/ZD cells harboring both EGFR exon 19 deletion and T790M mutations to increasing concentrations of osimertinib. Growth-inhibitory effect of inhibitors gefitinib and osimertinib was evaluated by MTT assay. Common EGFR mutational status was examined by RainDrop Digital PCR System (RainDance Technologies). Immunoblot analysis was performed to investigate the modulation of molecules relevant to EGFR signaling pathways. Cell-adhesion assay, wound closure assay and transwell assay were performed to evaluate the ability of cell adhesion and migration.

Results: Both PC-9/ZD/OR1 and PC-9/ZD/OR3 cells showed 50- to 120-fold more resistant to osimertinib than parental PC-9/ZD cells, and maintained resistance to gefitinib as well. PC-9/ZD/OR cells maintain EGFR exon 19 deletion and T790M mutations and C797S mutation was not detected. Although phosphorylation of EGFR and ERK1/2 were inhibited by osimertinib treatment in PC-9/ZD/OR cells, phosphorylation of Akt was not inhibited. PC-9/ZD/OR cells express the elevated level of c-MET and its phosphorylated form, suggesting that bypass signaling is activated to evade EGFR pathway blockade. PC-9/ZD/OR cells also express marked level of E-cadherin which parental PC-9/ZD cells do not express. PC-9/ZD/OR cells exhibited enhanced adherent activity, cell motility and migration ability compared to PC-9/ZD cells. Notably, osimertinib treatment significantly reduced the number of migrated cells not only in PC-9/ZD cells but also in PC-9/ZD/OR cells. These results suggest that osimertinib-resistant PC-9/ZD/OR cells acquired enhanced migration ability through c-MET pathway activation and/or induction of E-cadherin. Osimertinib treatment may be still effective to inhibit cell migration, suggesting that cell migration and cell growth are driven by different signaling pathways in PC-9/ZD/OR cells.

Conclusion: c-MET overexpression was suggested to confer resistance to osimertinib and the resistant cells exhibited enhanced cell migration. Continuative osimertinib treatment may be beneficial in preventing metastasis even after the failure and involvement of c-MET and E-cadherin in osimertinib resistance should be further investigated.

Citation Format: Satoshi Kambayashi, Yasuhiro Koh, Maiha Ohyama, Ayaka Tanaka, Hiroaki Akamatsu, Nahomi Tokudome, Hiroki Ueda, Nobuyuki Yamamoto. Increased migration ability of osimertinib-resistant EGFR-T790M mutant non-small-cell lung cancer cells [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 4149. doi:10.1158/1538-7445.AM2017-4149

Development of an automated size-based filtration system for isolation of circulating tumor cells in lung cancer patients

Circulating tumor cells (CTCs), defined as tumor cells circulating in the peripheral blood of patients with solid tumors, are relatively rare. Diagnosis using CTCs is expected to help in the decision-making for precision cancer medicine. We have developed an automated microcavity array (MCA) system to detect CTCs based on the differences in size and deformability between tumor cells and normal blood cells. Herein, we evaluated the system using blood samples from non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC) patients. To evaluate the recovery of CTCs, preclinical experiments were performed by spiking NSCLC cell lines (NCI-H820, A549, NCI-H23 and NCI-H441) into peripheral whole blood samples from healthy volunteers. The recovery rates were 70% or more in all cell lines. For clinical evaluation, 6 mL of peripheral blood was collected from 50 patients with advanced lung cancer and from 10 healthy donors. Cells recovered on the filter were stained. We defined CTCs as DAPI-positive, cytokeratin-positive, and CD45-negative cells under the fluorescence microscope. The 50 lung cancer patients had a median age of 72 years (range, 48–85 years); 76% had NSCLC and 20% had SCLC, and 14% were at stage III disease whereas 86% were at stage IV. One or more CTCs were detected in 80% of the lung cancer patients (median 2.5). A comparison of the CellSearch system with our MCA system, using the samples from NSCLC patients, confirmed the superiority of our system (median CTC count, 0 versus 11 for CellSearch versus MCA; p = 0.0001, n = 17). The study results suggest that our MCA system has good clinical potential for diagnosing CTCs in lung cancer.

Predictive impact of PD-L1-expressing circulating tumor cells in NSCLC patients treated with nivolumab

11541

Background: PD-L1 expression on tumor tissue is associated with response to PD-1 blockade in NSCLC. Here, we conducted a serial evaluation of PD-1-expressing circulating tumor cells (CTCs) as a potential real-time diagnostic modality in NSCLC patients treated with nivolumab. Methods: Advanced NSCLC patients after failure of at least one prior chemotherapy regimen received nivolumab monotherapy (3mg/kg, q2W) until progressive disease (PD) or unacceptable toxicity. Peripheral whole blood (3 mL) was collected for CTC evaluation at baseline and at week 4. CTCs were detected using microcavity array system (Hitachi Chemical Co., Ltd, Chikusei, Japan). PD-L1 expression was immunohistochemically examined on both tumor tissues and CTCs. This study was registered at UMIN (ID: 000024414). Results: Thirty patients were registered in the study between January 2016 and September 2016 at Wakayama Medical University Hospital and 29 were included in the analysis. Demographics of the patients were as follows: median age 70 (range, 49 to 86); male 73 %; stage IV, 100 %; squamous/non-squamous, 27/73 %. At baseline, CTCs were detected in all patients (median, 15; range, 1 to 90) and PD-L1-expressing CTCs were detected in 87% of patients. Tumor proportion score (TPS) of PD-L1 expression on CTCs ranged from 6% to 100%, indicating intrapatient heterogeneity. Matched tumor tissues were available from 14 patients and 7 showed the PD-L1 TPS ≥ 50%. No positive correlation was observed on PD-L1 expression between tumor tissues and CTCs based on TPS (R2 = 0.0035). Overall response rate was 25% (7/29), and disease control rate was 54% (15/29). Total CTC count was significantly decreased after nivolumab treatment at week 4 (p < 0.05), but no significant change was observed in PD-L1 TPS on CTC. Patients harboring CTCs with PD-L1 TPS 50% or more at baseline were significantly more likely to achieve non-PD than those harboring CTCs with TPS less than 50% (p < 0.05). Conclusions: This is the first report on a serial monitoring of PD-L1 expression on CTCs in patients treated with nivolumab. PD-L1-expressing CTCs are suggested to hold potential for predicting clinical benefit. Clinical trial information: 000024414.

Applicability of the Japanese equation for estimating glomerular filtration rate in patients with advanced-stage thoracic cancer

BACKGROUND

The 24-h creatinine clearance (24-h Ccr) and the Cockcroft-Gault equation (CG) are commonly used as markers of renal function in clinical practice. However, the utility of the Japanese equation for estimating glomerular filtration rate (eGFR) in cancer patients has not yet been evaluated. The aim of this cross-sectional study was to investigate the extent and correlating factors for differences between eGFR and both 24-h Ccr and CG in advanced-stage thoracic cancer patients.

METHODS

eGFR, 24-h Ccr, and CG were calculated in 90 patients with thoracic malignancies. We evaluated how these three parameters are affected by clinical factors, including age, body surface area, serum creatinine concentration, and body mass index.

RESULTS

eGFR and CG were significantly correlated with 24-h Ccr (r=0.64, p<0.001 and; r=0.67, p<0.001, respectively). However, the median value derived from eGFR was higher than the median 24-h Ccr and the CG value (74.0, 65.2, and 63.9mL/min, respectively). Age had a significant positive correlation with the differences between eGFR and both 24-h Ccr and CG value (r=0.30, p=0.005 and; r=0.47, p<0.001, respectively). The differences between eGFR and the other two parameters were significantly higher in older patients (age≥70 years) than in younger patients (age<70 years) (p=0.023, p<0.001, respectively).

CONCLUSIONS

eGFR is likely to overestimate the renal function of elderly cancer patients. A modified equation for evaluating the renal function of Japanese older patients might be needed.

Abstract 3151: Genetic profiling of circulating tumor cells (CTC) in metastatic breast cancer (MBC) patients

Introduction: Cancer-associated mutations are present in circulating cell free plasma tumor DNA (ptDNA). We have previously reported mutation profiles of DNA extracted from CTC (CTC-DNA) from two patients with MBC (#2 and 24 in table). Here, we report an expanded cohort with an updated gene panel.

Methods: We studied seven patients (two previously reported, along with five additional patients) with MBC who were enrolled in Mi-CTC-ONCOSEQ, had ≥5 CTC/7.5 ml whole blood (WB), and had at least one CTC with high quality DNA determined by the Ampli1™ quality control kit. CTC were enriched from WB with CellSearch© and purified from white blood cells (WBC) (DEPArray™). DNA from individual CTC and WBC was isolated and subjected to whole genomic amplification (Ampli 1™ WGA) and genotyped by multiplexed PCR-based next generation sequencing with the Oncomine Comprehensive Panel (OCP) on the Ion Torrent Proton. Exome sequencing of research biopsies of metastatic tissue was performed using an Illumina HiSeq 2500 platform. Previously reported patients (#2 and 24) sequenced with a beta version of the OCP were re-run, and updated results are provided.

Results: Six of seven patients were ER positive. Patients #2, 12, and 24 had CTC with mutations also found in the research biopsy (table). Novel alterations were found in comparison to research biopsy in five of the seven patients (table). In two patients (#19, 24), two potential actionable mutations (PTCH1 and NOTCH1) were found in CTC-DNA but not in tissue-DNA. No mutations were detected in any WBC.

Conclusions: We demonstrate the ability to purify CTC, and to isolate and amplify DNA of suitable quality for genetic analysis using a comprehensive targeted sequencing panel. Mutations found in tissue as well as novel mutations were found in CTC-DNA. Two potential actionable mutations were identified in CTC, but not in tissue, opening potentially new therapeutic opportunities. We conclude that mutational analysis of CTC-DNA and of tissue may be complementary. Prioritized mutations in CTCsPt #Gene (Mutation)# CTC Single (S) Pooled (P)# with mutation (variant fraction)# without mutation# not evaluable (insufficient coverage)# WBC (all pooled)# with mutationPresent in Biopsy?2CDH1 (p.Q641X)7 (S)5 (1.00)NA230YCDH1 (S70F)7 (S)5 (1.00)NA230YESR1 (p.Y537S)7 (S)4 (0.46)2130YESR1 (unreported mutation)7 (S)1 (0.56)5130N8NA3 (P)*NANA3 (P)40NA12PIK3CA (H1047R)1 (S)1 (0.85)NANA10YTP53 (p.R248Q)1 (S)1 (0.72)NANA10Y14HNF1A (p.W206C)3 (P)+ (0.17)NANA40N17BRCA2 (p.Q1931X)4 (P)+ (0.10)NANA40N19PTCH1 (p.E1242X)3 (P)+ (0.28)NANA30N24CDH1 (p.I584fs)5 (P)+ (0.79)NANA40Y4 (P)+ (0.68)4 (P)+ (0.77)CDH1 (p.E841X)5 (P)0NANA40N4 (P)+ (0.14)4 (P)0TP53 (p.152_156del)5 (P)+ (0.94)NANA40Y4 (P)+ (0.29)4 (P)+ (0.36)NOTCH1 (p.S2492X)5 (P)0 +NANA40N4 (P)(0.17)4 (P)0Legend: NA = not applicable; + = mutation present in pooled CTC; Y = Yes; N = No; *CTC-DNA from the pool of 3 CTC had low and high quality.

Citation Format: Costanza Paoletti, Andi K. Cani, Kimberly Aung, Elizabeth P. Darga, Emily M. Cannell, Daniel H. Hovelson, Maryam Yazdani, Allen R. Blevins, Nahomi Tokudome, Paul J. Baratta, Jose’ M. Larios, Dafydd G. Thomas, Martha E. Brown, Christina Gersch, Anne F. Schott, Daniel Robinson, Arul M. Chinnaiyan, Farideh Bischoff, Daniel F. Hayes, James M. Rae, Scott A. Tomlins. Genetic profiling of circulating tumor cells (CTC) in metastatic breast cancer (MBC) patients. [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 3151.

Abstract P2-02-19: Somatic genetic profiling of circulating tumor cells (CTC) in metastatic breast cancer (MBC) patients

Introduction: Somatic mutations, including those in TP53, PIK3CA, and estrogen receptor alpha (ESR1), are key to the biology of cancer and response to therapy. Recently, somatic cancer-associated mutations have been identified in circulating cell free plasma tumor DNA (ptDNA). Less is known about the mutation profile of DNA extracted from CTC (CTC-DNA). Since CTC-DNA provides mutational information of single cells, we hypothesize CTC-DNA will complement ptDNA to give greater insight into tumor heterogeneity.

Methods: Patients with ER positive MBC who were enrolled in the Mi CTC-ONCOSEQ, a companion trial to Mi-ONCOSEQ (the Michigan Oncology Sequencing Program), and who had ≥5CTC/7.5 ml whole blood were included. CTC were enriched from white blood cells (WBC) with CellSearch© (CXC kit). CTC and WBC were then purified using DEPArrayTM. DNA from individual CTC and WBC was isolated and subjected to whole genomic amplification (Ampli 1TM WGA). Genetic analysis was performed on individual CTC, pooled CTC and pooled WBC DNA by multiplexed PCR based targeted next generation sequencing (NGS) using the Oncomine Comprehensive Panel (targeting ∼130 onco- and tumor suppressor genes) and the Ion Torrent Proton. All patients had exome sequencing performed on research biopsies of metastases using an Illumina HiSeq 2500 platform.

Results: This pilot study was conducted using high quality DNA from two patients assessed to date. Both patients had lobular carcinoma and as expected harbored somatic, deleterious CDH1 (E-cadherin) mutations (frameshift and non-sense) in both research biopsy and CTC-DNA. These data supported our approach. Patient #1 was TP53 wild type in her research biopsy, but multiple CTC harbored somatic TP53 frame-shift mutations (Table). Patient #2 harbored an ESR1 Y537S mutation in her research biopsy. However, only 4 of 7 CTC also harbored this somatic, heterozygous mutation.

Prioritized mutations in CTCPt#Cell Type (CTC vs WBC), numberGeneMutationVariant fraction (expected 1=homozygous; 0.5=heterozygous)Found in research biopsy?1CTC_A2CDH1p.I584fs1YES CTC_A4  1  CTC_A7  0.54  CTC_pool*  0.74  WBC_pool  0  CTC_A2TP53p.152_156del1NO CTC_A4  1  CTC_A7  0.51  CTC_pool*  0.88  WBC_pool  0 2CTC_A9ESR1p.Y537S0.52YES CTC_D1  0.34  CTC_D2  0.46  CTC_D6  0.65  CTC_pool*  0.35  WBC_pool  0  CTC_A12  0  CTC_D3  0  CTC_D7  0  CTC_A12CDH1p.Q641X1YES CTC_A9  1  CTC_D1  1  CTC_D3  1  CTC_D6  1  CTC_pool*  1  WBC_pool  0 * pool of all CTC

Conclusions: We demonstrate the ability to purify CTC, isolate, and amplify DNA of suitable quality for genetic analysis using a comprehensive targeted sequencing panel. Both known and novel alterations were identified in comparison to research biopsy specimens. This approach allows single cell analysis demonstrating heterogeneity of mutational status in different single cells. Studies of CTC-ESR1 and other genetic abnormalities in patients with known tissue mutations who participated in Mi CTC-ONCOSEQ are now underway.

Citation Format: Paoletti C, Cani AK, Aung K, Darga EP, Cannell EM, Hovelson DH, Yazdani M, Blevins AR, Tokudome N, Larios JM, Thomas DG, Brown ME, Gersch C, Schott AF, Robinson DR, Chinnaiyan AM, Bischoff F, Hayes DF, Rae JM, Tomlins SA. Somatic genetic profiling of circulating tumor cells (CTC) in metastatic breast cancer (MBC) patients. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-02-19.

Abstract P3-05-01: Molecular analysis of cancer tissue, circulating tumor cells (CTC) and cell-free plasma tumor DNA (ptDNA) suggests variable mechanisms of resistance to endocrine therapy (ET) in estrogen receptor (ER) positive metastatic breast cancer (MBC)

Introduction: Fifty percent of ER positive MBC patients do not benefit from ET. Potential mechanisms of resistance to ET in this patient population include absence of ER expression by deletion or suppression, alteration in ER signaling pathway genes, or upregulation of multiple growth factor receptor pathways. We hypothesized that genotyping and phenotyping of CTC combined with genomic analysis of ptDNA will provide important insights into the multiple mechanisms of ET resistance and that a set of blood tests might serve as a "liquid biopsy" abrogating the need for tissue specimens.

Methods: Twenty-four patients providing informed consent were enrolled into the Mi CTC-ONCOSEQ study, a companion trial to Mi-ONCOSEQ (the Michigan Oncology Sequencing Program). Seven of these patients (5 with ER immunohistochemistry (IHC) positive and 2 with ER negative cancers) who had available archived primary and metastatic cancer tissue, a research metastatic biopsy for genomic analysis, and who had ≥5CTC/7.5 ml whole blood (WB) characterized for ER protein (CTC-ER) are the focus of this report. All the patients were ET refractory. None of them was progressing on fulvestrant at the time of study entry. CTC enumeration and phenotyping was performed with CellSearch©. Circulating ptDNA was analyzed by droplet digital polymerase chain reaction (ddPCR). ER status from archived tissue was obtained from chart review. ER mRNA expression was determined in the research biopsy of metastatic tissue by using quantitative RNA sequencing. Mutational status of ER gene, ESR1, was determined by Next-gen Sequencing using the Illumina HiSeq 2500 platform.

Results: The 2 control patients with triple negative breast cancer had negative CTC-ER. Discordance between CTC-ER and tissue ER by IHC was observed (Table). Two of the 5 ER positive patients retained CTC-ER positivity (39% and 19% of the CTC). One of them (#7) harbored an ESR1 mutation in the research biopsy tissue and in ptDNA, whereas the other (#14) had wild type (WT) ESR1. CTC-ER protein levels in patients #12, 17 and 24 were negative. All had WT ESR1 in the research biopsy tissue. Of note, patient #12 had WT ESR1 in the research biopsy, but an ESR1 mutation was detected in her ptDNA.

Pt#CTC-ER Tissue-ER  ESR1 status in research biopsyESR1 status in ptDNA N[deg]CTC/7.5ml WB% CTC-ER +Primary by IHCMet by IHCMet research biopsy by mRNA  71839%+++Y537SY537S141619%+NA+WTWT12130%+++WTD538G17160%++weakly+WTWT242750%+weakly+weakly+WTWT

Conclusions: These exploratory data suggest heterogeneous mechanisms of resistance to ET in patients with previously determined ER-positive MBC, including ESR1 mutations in ER positive cases (seen in 2 patients) and loss of ER expression (seen in CTC of 3 patients). In contrast, other cancers continue to express WT ESR1, and therefore must have developed alternative mechanisms of resistance. At least 2 of these mechanisms can be detected and monitored with complementary circulating assays: CTC and ptDNA. Further investigations are needed to understand the heterogeneous mechanisms of resistance to ET.

Citation Format: Paoletti C, Aung K, Cannell EM, Darga EP, Chu D, Kidwell KM, Thomas DG, Tokudome N, Brown ME, McNutt LM, Gersch C, Schott AF, Park BH, Robinson DR, Chinnaiyan AM, Rae JM, Hayes DF. Molecular analysis of cancer tissue, circulating tumor cells (CTC) and cell-free plasma tumor DNA (ptDNA) suggests variable mechanisms of resistance to endocrine therapy (ET) in estrogen receptor (ER) positive metastatic breast cancer (MBC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-05-01.

ESR1 Mutations in Circulating Plasma Tumor DNA from Metastatic Breast Cancer Patients

PURPOSE

Mutations in the estrogen receptor (ER)α gene, ESR1, have been identified in breast cancer metastases after progression on endocrine therapies. Because of limitations of metastatic biopsies, the reported frequency of ESR1 mutations may be underestimated. Here, we show a high frequency of ESR1 mutations using circulating plasma tumor DNA (ptDNA) from patients with metastatic breast cancer.

EXPERIMENTAL DESIGN

We retrospectively obtained plasma samples from eight patients with known ESR1 mutations and three patients with wild-type ESR1 identified by next-generation sequencing (NGS) of biopsied metastatic tissues. Three common ESR1 mutations were queried for using droplet digital PCR (ddPCR). In a prospective cohort, metastatic tissue and plasma were collected contemporaneously from eight ER-positive and four ER-negative patients. Tissue biopsies were sequenced by NGS, and ptDNA ESR1 mutations were analyzed by ddPCR.

RESULTS

In the retrospective cohort, all corresponding mutations were detected in ptDNA, with two patients harboring additional ESR1 mutations not present in their metastatic tissues. In the prospective cohort, three ER-positive patients did not have adequate tissue for NGS, and no ESR1 mutations were identified in tissue biopsies from the other nine patients. In contrast, ddPCR detected seven ptDNA ESR1 mutations in 6 of 12 patients (50%).

CONCLUSIONS

We show that ESR1 mutations can occur at a high frequency and suggest that blood can be used to identify additional mutations not found by sequencing of a single metastatic lesion.

Development of circulating tumor cell-endocrine therapy index in patients with hormone receptor-positive breast cancer

BACKGROUND

Endocrine therapy (ET) fails to induce a response in one half of patients with hormone receptor (HR)-positive metastatic breast cancer (MBC), and almost all will eventually become refractory to ET. Circulating tumor cells (CTC) are associated with worse prognosis in patients with MBC, but enumeration alone is insufficient to predict the absolute odds of benefit from any therapy, including ET. We developed a multiparameter CTC-Endocrine Therapy Index (CTC-ETI), which we hypothesize may predict resistance to ET in patients with HR-positive MBC.

METHODS

The CTC-ETI combines enumeration and CTC expression of four markers: estrogen receptor (ER), B-cell lymphoma 2 (BCL-2), Human Epidermal Growth Factor Receptor 2 (HER2), and Ki67. The CellSearch System and reagents were used to capture CTC and measure protein expression by immunofluorescent staining on CTC.

RESULTS

The feasibility of determining CTC-ETI was initially established in vitro and then in a prospective single-institution pilot study in patients with MBC. CTC-ETI was successfully determined in 44 of 50 (88%) patients. Eighteen (41%), 9 (20%), and 17 (39%) patients had low, intermediate, and high CTC-ETI scores, respectively. Interobserver concordance of CTC-ETI determination was from 94% to 95% (Kappa statistic, 0.90-0.91). Inter- and cell-to-cell intrapatient heterogeneity of expression of each of the CTC markers was observed. CTC biomarker expression was discordant from both primary and metastatic tissues.

CONCLUSIONS

CTC expression of ER, BCL-2, HER2, and Ki67 can be reproducibly measured with high analytical validity using the CellSearch System. The clinical implications of CTC-ETI, and of the heterogeneity of CTC biomarker expression, are being evaluated in an ongoing prospective trial.

Abstract PD6-4: Heterogeneity of expression of estrogen receptor by circulating tumor cells suggests diverse mechanisms of resistance to fulvestrant in metastatic breast cancer patients

Introduction: Fulvestrant is a selective estrogen receptor down-regulator (SERD). Recent studies have shown that the efficacy of fulvestrant is dose-related. However, at the higher dose (500 mg/month) most cancers develop resistance and progress. We previously reported expression of several markers, including estrogen receptor (ER) and BCL-2, on breast cancer circulating tumor cells (CTC) using CellSearch®. We now report pilot data showing inter-patient heterogeneity of these markers on CTC in patients with known ER positive breast cancer whose disease is progressing on fulvestrant.

Methods: We conducted a pilot trial to determine the analytical validity of measuring expression of markers of endocrine sensitivity (ER, BCL-2) or resistance (HER-2, Ki-67) with fluorescent-labeled antibodies using the CellSearch® system. Patients with ER positive metastatic breast cancer (MBC) whose disease was progressing on any type of therapy were eligible after signed informed consent. This report is limited to the subjects who were progressing on fulvestrant. Whole blood (WB) was characterized for CTC counts and each of the four molecular markers using the CXC CellSearch® kit.

Results: Of 50 enrolled patients, seven were progressing on fulvestrant. Two patients had no detectable CTC, while five patients had an average of ≥5 CTC/7.5 mL WB. Results are shown in a table below:

   CTC-ERCTC-BCL-2Patient #Fulvestrant dose (mg/month)Days since last doseN CTC/7.5 mL of WB% of CTC-ER+N CTC/7.5 mL of WB% of CTC-BCL-2+295002880%110%4550028170%170%2250341010%714%850031812%1735%172507728%367%

These exploratory data suggest widely different mechanisms of resistance to fulvestrant in different patients with ER positive MBC. In two of the patients (29, 45) treated with 500 mg/month, both CTC-ER and CTC-BCL-2 expression were absent, suggesting no signaling through the ER pathway. We hypothesize either that fulvestrant was actively down-regulating ER, but the cancers had adopted other growth and survival pathways, or that ER negative, hormone-independent clones had evolved. In the other three cases, ER was clearly present with evidence of signaling, based on BCL-2 expression. Two of these patients (2, 17) were on the lower dose of fulvestrant, now considered to be less effective. However, the third (8) was on the higher dose and yet still had evidence of ER signaling. This observation suggests that some patients may benefit from even higher doses of SERD therapy.

Conclusions: These pilot results suggest heterogeneous biological or pharmacological mechanisms of resistance to SERD therapy. These data suggest that CTC-ER and CTC-BCL-2 expression could serve as pharmacodynamic monitoring tools for dose escalation of fulvestrant or other SERDs. Further molecular analysis might provide biological bases for resistance to fulvestrant.

Supported by Veridex, LLC, Fashion Footwear Charitable Foundation of New York/QVC Presents Shoes on Sale™ (DFH), Associazione Sandro Pitigliani and by a studentship from FIRC (CP).

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD6-4.