Cost-Utility and Budget Impact Analyses of Oral Chemotherapy for Stage III Colorectal Cancer: Real-World Evidence after Policy Implementation in Thailand

This study conducted a cost-utility analysis and a budget impact analysis (BIA) of outpatient oral chemotherapy versus inpatient intravenous chemotherapy for stage III colorectal cancer (CRC) in Thailand. A Markov model was constructed to estimate the lifetime cost and health outcomes based on a societal perspective. Eight chemotherapy strategies were compared. Clinical and cost data on adjuvant chemotherapy were collected from the medical records of 1747 patients at Siriraj Hospital, Thailand. The cost-effectiveness results were interpreted against a Thai willingness-to-pay threshold of USD 5003/quality-adjusted life year (QALY) gained. A 5-year BIA was performed. Of the eight strategies, CAPOX then FOLFIRI yielded the highest life-year and QALY gains. Its total lifetime cost was also the highest. An incremental cost-effectiveness ratio of CAPOX then FOLFIRI compared to 5FU/LV then FOLFOX, a commonly used regimen USD was 4258 per QALY gained.The BIA showed that when generic drug prices were applied, 5-FU/LV then FOLFOX had the smallest budgetary impact (USD 9.1 million). CAPOX then FOLFIRI required an approximately three times higher budgetary level (USD 25.1 million). CAPOX then FOLFIRI is the best option. It is cost-effective compared with 5-FU/LV then FOLFOX. However, policymakers should consider the relatively high budgetary burden of the CAPOX then FOLFIRI regimen.

Abstract 6588: Systems biology-based drug repositioning and biomarker discovery for Thai liver fluke-associated cholangiocarcinoma

Our group has recently reported the successful use of comprehensive drug response and pan-omic profiling for identifying repurposable drug shortlists in Asian cholangiocarcinoma. We also developed the CCA45 gene-expression signature that could accurately predict the prognosis of CCA patients, especially those with Asian ethnic backgrounds. To further explore therapeutic candidates and potential resistance mechanisms, we have established CCA1 cell lines resistant to their subgroup-specific drug candidates: MEK and SRC inhibitors. Reverse-phase protein arrays (RPPA)-based proteomic profiling revealed upregulation of cell cycle, apoptosis, MAPK, and mTOR-related proteins in both MEKi- and SRCi-resistant cells. Src pathway activity was found to be more significantly reduced in SRCi-resistant cells. We identified CDK4/6 inhibitors as the second-line therapeutic candidates for MEK inhibitor-resistant cells by systematic drug screening. SRCi-resistant cells unexpectedly developed cross-resistance to MEK inhibitors and showed sensitivity to only a few CDK4/6 inhibitors. These data are beneficial for the clinical translation of our proposed drug candidates for Asian CCA, preparing the alternate regimens after drug resistance. We also adopted the DSP-based spatial transcriptomic platform to compare the tumor microenvironment between chemotherapy-sensitive and chemotherapy-resistant CCA patients. While the CTA panel showed consistent patterns of normalized gene expression to those of the WTA panel, the CTA panel can only measure 17 of the 45 genes required for our CCA45 signature. Out of these 17 genes, ITGB4, FGFR3, VEGFC, NOTCH1, and RRAD showed significant gene expression changes with reducing tumor percentage. The microenvironment of gemcitabine/cisplatin responder (R) non-responder (NR) exhibited negative regulation of ERK1/2 and MAPK, high WNT pathway activity, and high tumor-infiltrating lymphocyte (TIL). In contrast, the microenvironment of the non-responder (NR) subgroup showed high neutrophil-related activity, high NFκB, high Treg, and the exhausted immune phenotype. Overall, our study contributes toward realizing the precision medicine concept for CCA patients.

Citation Format: Supawan Jamnongsong, Patipark Kueanjinda, Piyathida Tawornparcha, Kulthida Vaeteewoottacharn, Seiji Okada, Siwanon Jirawatnotai, Ananya Pongpaibul, Krittiya Korphaisarn, Somponnat Sampattavanich. Systems biology-based drug repositioning and biomarker discovery for Thai liver fluke-associated cholangiocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6588.

The KRAS-Mutant Consensus Molecular Subtype 3 Reveals an Immunosuppressive Tumor Microenvironment in Colorectal Cancer

Colorectal cancers (CRC) with KRAS mutations (KRAS^mut) are frequently included in consensus molecular subtype 3 (CMS3) with profound metabolic deregulation. We explored the transcriptomic impact of KRAS^mut, focusing on the tumor microenvironment (TME) and pathways beyond metabolic deregulation. The status of KRAS^mut in patients with CRC was investigated and overall survival (OS) was compared with wild-type KRAS (KRAS^wt). Next, we identified CMS, and further investigated differentially expressed genes (DEG) of KRAS^mut and distinctive pathways. Lastly, we used spatially resolved gene expression profiling to define the effect of KRAS^mut in the TME regions of CMS3-classified CRC tissues. CRC patients with KRAS^mut were mainly enriched in CMS3. Their specific enrichments of immune gene signatures in immunosuppressive TME were associated with worse OS. Activation of TGFβ signaling by KRAS^mut was related to reduced pro-inflammatory and cytokine gene signatures, leading to suppression of immune infiltration. Digital spatial profiling in TME regions of KRAS^mut CMS3-classified tissues suggested up-regulated genes, CD40, CTLA4, ARG1, STAT3, IDO, and CD274, that could be characteristic of immune suppression in TME. This study may help to depict the complex transcriptomic profile of KRAS^mut in immunosuppressive TME. Future studies and clinical trials in CRC patients with KRAS^mut should consider these transcriptional landscapes.

Corrigendum: Combining the SMAC mimetic LCL161 with Gemcitabine plus Cisplatin therapy inhibits and prevents the emergence of multidrug resistance in cholangiocarcinoma

[This corrects the article DOI: 10.3389/fonc.2022.1021632.].

Combining the SMAC mimetic LCL161 with Gemcitabine plus Cisplatin therapy inhibits and prevents the emergence of multidrug resistance in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a highly lethal gastrointestinal malignancy that has one of the worst prognoses among solid tumors. The combination of Gemcitabine + Cisplatin (GEM/CIS) remains the standard first-line treatment for advanced stage CCA. However, this drug combination yields only a modest objective response rate, and in cases that initially respond to this treatment, drug resistance commonly rapidly develops. To improve the efficiency of GEM/CIS therapy for CCA, a thorough understanding of the mechanism of GEM/CIS resistance in CCA is required. To that end - in this study, we developed several acquired GEM/CIS-resistant CCA cell lines and we screened those cell lines for acquired vulnerability. The screening process revealed that subset of CCA with GEM/CIS resistance acquired vulnerability to the small-molecule second mitochondrial-derived activator of caspases (SMAC) mimetics LCL161 and Birinapant. The observed acquired vulnerability was found to be associated with upregulation of an inhibitor of apoptosis protein 2 (cIAP2), a known target of SMAC mimetics. LCL161 or cIAP2-shRNA downregulated cIAP2 and restored the sensitivity to GEM/CIS in GEM/CIS-resistant CCA cell lines and in in vivo GEM/CIS-resistant xenograft models. A strong synergic effect was observed when LCL161 was added to GEM/CIS. Interestingly, this synergism was also observed in drug-naïve CCA cell lines, xenografts, and patient-derived organoids. This triplet therapy also prevented the emergence of multidrug-resistant CCA in in vitro and in vivo models. Our findings suggest that activation of cIAP2 allows CCA to escape GEM/CIS, and that suppression of cIAP2 reestablishes the apoptotic profile of CCA, thus restoring its vulnerability to GEM/CIS. The results of this study indicate that combining the SMAC mimetic LCL161 with GEM/CIS inhibits and prevents the emergence of multidrug resistance in CCA.

Efficacy, Safety, and Patient-Reported Outcomes of Atezolizumab Plus Bevacizumab for Unresectable Hepatocellular Carcinoma in Thailand: A Multicenter Prospective Study

PURPOSE

Atezolizumab plus bevacizumab treatment is a first-line therapy for unresectable hepatocellular carcinoma (HCC) worldwide. The efficacy, safety, and patient-reported outcomes (PROs) of HCC in Thailand have not yet been reported. This study aimed to evaluate the efficacy, safety, and PROs of atezolizumab plus bevacizumab.

MATERIALS AND METHODS

From September 2020 to August 2021, 30 patients with unresectable HCC who met the inclusion criteria of atezolizumab plus bevacizumab as first-line treatment were enrolled. Analysis was assessed for progression-free survival, overall survival, adverse events (AEs), and quality of life (QoL).

RESULTS

The median progression-free survival and overall survival periods were 6.7 and 10.2 months, respectively. The disease control rate was 63.3%. The frequent AEs were proteinuria, hypertension, and hepatitis. Serious AEs included gastrointestinal bleeding, but none of the patients died from serious AEs. The discontinuation rate was 23.3%, and the median number of treatment cycles was 10.5 cycles. In total, 23.3% of the patients continued treatment after 1 year of therapy. The global health status/QoL and physical function scores showed less deterioration at baseline than at 3 and 6 months (median scores = 76.7, 71.6, and 64.1 in QoL and 84.7, 79.6, and 79.0 in physical function, respectively). The HCC18 symptom score index data showed a slow progression of symptom scores from baseline to 3 and 6 months (12.7, 19.6, and 22.3, respectively).

CONCLUSION

This study demonstrates that atezolizumab plus bevacizumab is effective and has a safety profile comparable with that of previous studies as first-line therapy for unresectable HCC in a real-world setting and in Thai populations. Data on PROs also demonstrate benefits in terms of patients' QoL and symptoms.

Primary pulmonary lymphoepithelioma-like carcinoma treated with immunotherapy: A case report and literature review

Here, we report a case of metastatic Epstein–Barr virus (EBV)‐related primary pulmonary lymphoepithelioma‐like carcinoma (PPLELC) in a young, nonsmoking female who responded well to treatment with two types of immune checkpoint inhibitors (ICIs). This is the first case report of a favorable outcome to ICIs in the late‐line treatment of advanced PPLELC patients with programmed cell death‐ligand 1 (PD‐L1) expression.

The Acquired Vulnerability Caused by CDK4/6 Inhibition Promotes Drug Synergism Between Oxaliplatin and Palbociclib in Cholangiocarcinoma

Cholangiocarcinoma (CCA) is one of the most difficult to treat cancers, and its nature of being largely refractory to most, if not all, current treatments results in generally poor prognosis and high mortality. Efficacious alternative therapies that can be used ubiquitously are urgently needed. Using acquired vulnerability screening, we observed that CCA cells that reprofile and proliferate under CDK4/6 inhibition became vulnerable to ribosomal biogenesis stress and hypersensitive to the anti-ribosome chemotherapy oxaliplatin. CCA cells overexpress the oncogenic ribosomal protein RPL29 under CDK4/6 inhibition in a manner that correlated with CDK4/6 inhibitor resistance. Depletion of RPL29 by small interfering RNAs (siRNAs) restored the sensitivity of CCA cells to CDK4/6 inhibition. Oxaliplatin treatment suppressed the RPL29 expression in the CDK4/6 inhibitor treated CCA cells and triggered RPL5/11-MDM2-dependent p53 activation and cancer apoptosis. In addition, we found that combination treatment with oxaliplatin and the CDK4/6 inhibitor palbociclib synergistically inhibited both parental and CDK4/6 inhibitor-resistant CCA, and prevented the emergence of CDK4/6 and oxaliplatin-resistant CCA. This drug combination also exerted suppressive and apoptosis effects on CCA in the in vitro 3-dimensional culture, patient-derived organoid, and in vivo xenograft CCA models. These results suggest the combination of the CDK4/6 inhibitor palbociclib and the anti-ribosome drug oxaliplatin as a potentially promising treatment for cholangiocarcinoma.

Effect of Primary Tumor Location on Second- or Later-Line Treatment With Anti-Epidermal Growth Factor Receptor Antibodies in Patients With Metastatic Colorectal Cancer: A Retrospective Multi-Center Study

BACKGROUND

Current guidelines recommend anti-epidermal growth factor receptor monoclonal antibodies (anti-EGFR Ab) as first-line treatment only in patients with left-sided RAS wild type (RASwt) metastatic colorectal cancer (mCRC). However, there are no guideline recommendations specific to tumor sidedness in subsequent-line treatment. This study aimed to investigate the effect of primary tumor location on second- or later-line treatment outcomes in patients with KRASwt mCRC.

METHODS

Medical records of patients diagnosed with mCRC at 3 academic centers in Thailand (Siriraj, Chulalongkorn, and Ramathibodi hospital) between 2008 and 2019 were retrospectively reviewed. Patients with KRASwt mCRC who received anti-EGFR Ab in second- or later-line treatment were included. The impact of tumor sidedness on progression-free survival (PFS) was determined using Kaplan-Meier method, and those results were compared using log-rank test.

RESULTS

Among the 2,102 patients who had KRAS analysis data, 1,130 (54%) patients had KRASwt. Of those, 413 patients received anti-EGFR Ab in second- or later-line treatment. One hundred and sixty-two of 413 (39%) patients had extended RAS analysis. Seventy (17%) patients had right-sided tumors. Two hundred and thirty-eight (58%) patients received anti-EGFR Ab in the third line, and 132 (32%) patients and 43 (10%) patients were treated in the second and more than third line, respectively. Single-agent irinotecan was the most commonly used backbone chemotherapy (303/413, 73%). Patients with right-sided tumors had non-significantly inferior PFS compared to patients with left-sided tumors (median PFS: 5.7 months (mo), 95% confidence interval [CI]: 3.9-7.5 vs. 7.5 mo, 95% CI 6.5-8.5; p=0.17). Subgroup analysis showed no difference in PFS when stratified by treatment lines. Patient with right-sided tumors had significantly inferior OS compared to patients with left-sided tumors (median OS: 23.3 mo vs. 29.9 mo; p=0.005).

CONCLUSIONS

To date, this is the largest real world data of the effect of primary tumor location on anti-EGFR Ab which demonstrated that tumor sidedness has no significant impact on treatment outcomes in KRASwt mCRC patients receiving second- or later-line therapy. Our findings do not support the utility of tumor sidedness for treatment selection in these settings. We confirmed that patients with right-sided tumors had significantly worse survival.

Co-occurrence CDK4/6 amplification serves as biomarkers of de novo EGFR TKI resistance in sensitizing EGFR mutation non-small cell lung cancer

Despite the development of predictive biomarkers to shape treatment paradigms and outcomes, de novo EGFR TKI resistance advanced non-small cell lung cancer (NSCLC) remains an issue of concern. We explored clinical factors in 332 advanced NSCLC who received EGFR TKI and molecular characteristics through 65 whole exome sequencing of various EGFR TKI responses including; de novo (progression within 3 months), intermediate response (IRs) and long-term response (LTRs) (durability > 2 years). Uncommon EGFR mutation subtypes were significantly variable enriched in de novo resistance. The remaining sensitizing EGFR mutation subtypes (exon 19 del and L858R) accounted for 75% of de novo resistance. Genomic landscape analysis was conducted, focusing in 10 frequent oncogenic signaling pathways with functional contributions; cell cycle, Hippo, Myc, Notch, Nrf2, PI-3-Kinase/Akt, RTK-RAS, TGF-β, p53 and β-catenin/Wnt signaling. Cell cycle pathway was the only significant alteration pathway among groups with the FDR p-value of 6 × 10^-4. We found only significant q-values of < 0.05 in 7 gene alterations; CDK6, CCNE1, CDK4, CCND3, MET, FGFR4 and HRAS which enrich in de novo resistance [range 36-73%] compared to IRs/LTRs [range 4-22%]. Amplification of CDK4/6 was significant in de novo resistance, contrary to IRs and LTRs (91%, 27.9% and 0%, respectively). The presence of co-occurrence CDK4/6 amplification correlated with poor disease outcome with HR of progression-free survival of 3.63 [95% CI 1.80-7.31, p-value < 0.001]. The presence of CDK4/6 amplification in pretreatment specimen serves as a predictive biomarker for de novo resistance in sensitizing EGFR mutation.

Effect of primary tumor location on second- or later-line treatment with anti-epidermal growth factor receptor antibodies in patients with metastatic colorectal cancer: A retrospective multicenter study

195

Background: Currently, there are no guideline recommendations of anti-EGFR Ab specific to tumor sidedness in subsequent-line treatment in patients with metastatic colorectal cancer (mCRC). We previously reported the effect of primary tumor location on subsequent-line treatment with anti-EGFR Ab from a single center. Here we presented the outcome from a multi-center study. Methods: Medical records of patients diagnosed with mCRC at 3 academic centers in Thailand (Siriraj, Chulalongkorn, and Ramathibodi hospital) between 2008 and 2019 were retrospectively reviewed. Patients with KRASwt mCRC who received anti-EGFR Ab in second- or later-line treatment were included. The impact of tumor sidedness on progression-free survival (PFS) was determined using Kaplan-Meier method, and those results were compared using log-rank test. Results: Among the 2,102 patients who had KRAS analysis data, 1,130 (54%) patients had KRASwt. Of those, 413 patients received anti-EGFR Ab in second- or later-line treatment. One hundred and sixty-two of 413 (39%) patients had extended RAS analysis. Seventy (17%) patients had right-sided tumors. Two hundred and thirty-eight (58%) patients received anti-EGFR Ab in the third line, and 132 (32%) patients and 43 (10%) patients were treated in the second and more than third line, respectively. Single-agent irinotecan was the most commonly used backbone chemotherapy (303/413, 73%). Patients with right-sided tumors had non-significantly inferior PFS compared to patients with left-sided tumors (median PFS: 5.7 months (mo), 95% confidence interval [CI]: 3.9-7.5 vs. 7.5 mo, 95% CI 6.5-8.5; p =0.17). Subgroup analysis showed no difference in PFS when stratified by treatment lines. Patient with right-sided tumors had significantly inferior OS compared to patients with left-sided tumors (median OS: 23.3 mo vs. 29.9 mo; p =0.005). Conclusions: To date, this is the largest real world data of the effect of primary tumor location on anti-EGFR Ab which demonstrated that tumor sidedness has no significant impact on treatment outcomes in KRASwt mCRC patients receiving second- or later-line therapy. Our findings do not support the utility of tumor sidedness for treatment selection in these settings. We confirmed that patients with right-sided tumors had significantly worse survival.

Low Fat-Free Mass Index Measured by Bioelectrical Impedance Analysis Correlates With Hematologic Adverse Events in Early-Stage Breast Cancer Patients Receiving Chemotherapy: A Prospective Observational Cohort Study

Background: Low muscle mass is associated with worse cancer treatment outcomes. Although dual-energy X-ray absorptiometry or computerized tomography-based analysis have both been widely studied in this clinical setting, studies in the use of bioelectrical impedance analysis (BIA) remain limited. The aim of this prospective study was to investigate for association between body composition estimated by BIA and hematologic adverse events in early-stage breast cancer patients receiving chemotherapy. Methods: A total of 144 female patients were enrolled. Before the first cycle of chemotherapy, body weight and fat-free mass were measured by a BIA device and then those values were converted into body mass index and fat-free mass index. Association between fat-free mass index and composite adverse events (CAEs), including grade 4 neutropenia, febrile neutropenia, or relative dose intensity <85%, was explored. Results: CAEs occurred in 85 patients (59%), and point biserial correlation showed an inverse correlation between the fat-free mass index and CAE. No included patients were sarcopenic (fat-free mass index <11.4 kg/m²). Receiver operating characteristic curve analysis revealed <14.85 kg/m² as the cutoff value indicating a low fat-free mass index. Using this cutoff, 85 patients were classified as having a low fat-free mass index, and 62 of those patients (72.9%) had CAE (relative risk: 1.86, P < .001). After adjusting for other factors, a low fat-free mass index was found to be independently associated with a high CAE (adjusted odds ratio: 4.562, 95% CI: 2.162-9.627, P < .001). Conclusion: Low fat-free mass index is an independent predictor of increased risk of hematologic adverse events in early-stage breast cancer patients receiving chemotherapy. Estimation of fat-free mass index by BIA may identify at-risk patients so that interventions can be considered to improve treatment outcomes.

Loss of CDX-2 expression is an independent poor prognostic biomarker in patients with early-stage deficient mismatch repair colorectal cancer

AIM

To investigate the clinicopathological factors, molecular features, and prognostic implications associated with loss of Caudal-related homeobox transcription factor 2 (CDX-2) expression in colorectal cancer (CRC) patients.

METHODS

Immunohistochemistry for CDX-2 expression was performed on formalin-fixed, paraffin-embedded primary CRC tissue samples from 449 patients. Correlation between CDX-2 expression and clinicopathological and molecular characteristics was evaluated. Univariate and multivariate survival analyses were performed to determine the prognostic value of loss of CDX-2 expression.

RESULTS

Of 449 patients, 84% were stage I-III. CDX-2-negative expression was identified in 18 of 441 (4.1%) patients. Loss of CDX-2 expression was more commonly found in patients with right-sided tumors rather than left-sided tumors (odds ratio [OR] = 3.57; p = 0.009), deficient mismatch repair (dMMR) compared to proficient MMR (pMMR) (OR = 3.7; p = 0.012), and BRAF mutation compared to BRAF wild type (OR = 8.06; p = 0.002). Univariate analysis revealed that stage I-III CRC patients with loss of CDX-2 expression had significantly worse overall survival (OS) and disease-free survival (DFS) than those with positive CDX-2 expression (5-year OS = 33.3% vs. 74.6%, respectively; p < 0.001, and 5-year DFS: 42.9% vs. 69.5%, respectively; p = 0.004). Loss of CDX-2 expression remained significantly associated with worse OS compared to positive CDX-2 expression in multivariate analysis (hazard ratio [HR] = 2.4; 95% confidence interval [CI], 1.12-5.11; p = 0.023).

CONCLUSIONS

Loss of CDX-2 expression was found to be associated with right-sided tumor, dMMR status, and BRAF mutation. Moreover, loss of CDX-2 expression is a poor prognostic factor for OS in stage I-III, even among patients with dMMR tumors.

The effect of primary tumor location on second- or later-line treatment with anti-EGFR antibodies in patients with metastatic colorectal cancer: A single-center cohort study

3541

Background: The guideline recommends anti-EGFR monoclonal antibodies (anti-EGFR Ab) as first-line treatment only for patients with left-sided RAS wild type (RASwt) metastatic colorectal cancer (mCRC). However, there are no recommendations on tumor sidedness in subsequent lines. This study aimed to evaluate the effect of primary tumor location on second- or later-line treatment outcomes in patients with KRASwt mCRC. Methods: Medical records of patients diagnosed with mCRC at Siriraj Hospital between 2008 and 2019 were retrospectively reviewed. Patients with KRASwt who received anti-EGFR Ab in second- or later-line treatment were included. The impact of tumor sidedness on progression-free survival (PFS) was determined using the Kaplan-Meier method and compared using the log-rank test. Results: Of 671 patients who had data on KRAS analysis, 396 patients (59%) had KRASwt. Of these, 210 patients received anti-EGFR Ab in second- or later-line treatment. Twenty-nine percent of patients (60 out of 210) had extended RAS analysis. Thirty patients (14%) had right-sided tumors, while 180 patients (86%) had left-sided tumors. Sixty-nine percent of patients (146 of 210) were treated in the third line, while 19% and 12% were treated in the second and the fourth line, respectively. Single-agent irinotecan was the most commonly used chemotherapy backbone (92%). Patients with right-sided tumors had non-significantly inferior PFS compared with patients with left-sided tumors (median PFS was 4.7 months, 95% CI 0.8–8.7 vs. 6 months, 95% CI 4.6–7.3; p = 0.55). Subgroup analysis on the impact of primary tumor location showed no difference in PFS when stratified by treatment lines. Conclusions: This study demonstrated that tumor sidedness has no impact on treatment outcomes in patients treated with anti-EGFR Ab in second- or later-line treatment. Therefore, there is not enough evidence to use tumor sidedness for treatment selection in these settings. A multi-center retrospective study is ongoing.

Whole-exome sequencing in advanced-stage sensitizing EGFR mutation non-small cell lung cancer: Explore resistance biomarkers to EGFR TKI treatment

9039

Background: Despite the development of predictive biomarkers to shape treatment paradigms and outcomes, 10-20% of de novo EGFR TKI resistance advanced non-small cell lung cancer (NSCLC) in the presence of EGFR mutation remains the issue of concern. Methods: We explored clinical factors in 332 advanced NSCLC who received EGFR TKI and molecular characteristics through 65 whole exome sequencing of various EGFR TKI responses including; de novo (progression within 3 months), intermediate response (IRs) and long-term response (LTRs) (durability > 2 year). Results: Uncommon EGFR mutation subtype was a significant variable in de novo resistance vs. IRs and LTRs with odd ratios of 6.83 ([95% CI 2.36 – 19.80], p-value < 0.001) and 16.84 ([95%CI 1.66 – 171.45, p-value 0.02), respectively. The remaining sensitizing EGFR mutation subtype (exon 19 del and L858R) accounted for 75% of de novo resistance. Genomic landscape analysis was conducted, focusing in 10 frequent oncogenic signaling pathways with functional contributions; cell cycle, Hippo, Myc, Notch, Nrf2, PI-3-Kinase/Akt, RTK-RAS, TGF-β, p53 and β-catenin/Wnt signaling. Cell cycle pathway was the only significant alteration pathway among groups with the FDR p-value of 6×10-4. We found only significant q-values of < 0.05 in 7 gene alterations; CDK6, CCNE1, CDK4, CCND3, MET, FGFR4 and HRAS which enrich in de novo resistance [range 36-73%] compared to IRs/LTRs [range 4-22%]. Amplification of CDK4/6 was significant in de novo resistance, contrary to IRs and LTRs (91%, 27.9% and 0%, respectively). The presence of co-occurrence CDK4 /6 amplification correlated with poor disease outcome with HR of progression-free survival of 3.63 [95% CI 1.80-7.31, p-value < 0.001]. Conclusions: The presence of CDK4 /6 amplification in pretreatment specimen serve as a predictive biomarker for de novo resistance in sensitizing EGFR mutation.

Efficacy of Combination Docetaxel and Nintedanib in Advanced Non-Small Cell Lung Cancer in Thailand: A Multicenter Study

Introduction

The mainstay systemic treatment for non-oncogenic addictive advanced stage non-small cell lung cancer is chemotherapy. Anti-angiogenic agents are additive compounds that enhance disease control and lead to improvement of overall survival benefit. Recently PD-(L)1 blockage, a checkpoint inhibitor, has been adopted as another line of treatment. A sequential strategy to enhance the efficacy of combination docetaxel and nintedanib after immunotherapy, correlated with genomic mutation, has been explored.

Method

A retrospective cohort study of 56 patients from 8 centers in Thailand who received combination docetaxel and nintedanib via the Thai nintedanib Named Patient Use program was conducted. Demographic characteristics, treatment details, and treatment responses were retrieved from medical records.

Results

The majority of patients were male (62.5%) with adenocarcinoma subtype (88%). Thirty-five percent had sensitizing EGFR mutation. Combination docetaxel and nintedanib was given as second to fourth line of treatment. Median PFS of docetaxel/nintedanib was 5.6 months [95% CI 4.8-6.9]. Median OS of the entire cohort was 22.5 months [95% CI 20.2-31.1]. Among them, only four patients received this combination after immunotherapy which limited the validity of efficacy analysis. Median PFS of those four patients was 7.9 months [range 5.2-9.1] which was slightly higher than the remaining cohort (median PFS 4.5 months, 95% CI: 4.0-6.0, p-value 0.09). Among the adenocarcinoma subtype, a relapse-time of platinum-doublet chemotherapy of more than 6 months was solely indicated as a benefit of combination docetaxel/nintedanib treatment compared to the relapse-time of platinum-doublet chemotherapy of less than 6 months by multivariate HR of PFS 0.32 [95% CI: 0.14-0.68, p-value 0.003].

Conclusion

Combination docetaxel and nintedanib provided more benefit in relapse-time of platinum-doublet chemotherapy of more than 6 months in advanced stage adenocarcinoma lung cancer. Neither EGFR nor ALK alteration influenced the outcome of treatment.

Clinicopathological Characteristics and Outcome of Adolescent and Young Adult-Onset Microsatellite Stable Colorectal Cancer Patients

Purpose: Colorectal cancer (CRC) incidence is increasing in adults younger than 50 years. This study evaluated clinicopathological characteristics and outcome of adolescent and young adult (AYA)-onset sporadic CRC patients. Methods: Medical records of patients who were diagnosed adenocarcinoma of colon or rectum at Siriraj Hospital between 2007 and 2018 were retrospectively reviewed. The patients were classified into two groups: AYA-onset CRC (age 15-39 years) and adult-onset CRC (age >50 years). Associations between sporadic microsatellite stable (MSS) AYA-/adult-onset CRC and clinicopathological features and outcome were evaluated. Results: A total of 203 patients were diagnosed with AYA-onset CRC with no known history of familial CRC syndromes, 119 had data on mismatch repair status; 98 confirmed MSS CRC. AYA-onset CRC patients were commonly found with left-sided rather than right-sided tumors (77.1% vs. 22%) and late stage of disease (80.7% in stage III-IV vs. 19.3% in stage I-II). Compared with adult-onset CRC (218 patients), AYA-onset MSS CRC had more patients with female gender (p = 0.038), perineural invasion (p = 0.003), and signet ring cell/mucinous histology (p = 0.132). On univariate analysis, male gender and mucinous/signet ring cell histology had worse overall survival (OS) (p = 0.004 and p = 0.072, respectively) and remained significant in multivariate analysis for signet ring cell histology (p = 0.008). There was no difference in disease-free survival and OS between both age groups. Conclusions: Sporadic MSS AYA-onset CRC patients were associated with female gender and aggressive pathological characteristics. However, there was no difference in survival outcome between AYA-onset and adult-onset groups.

Consensus molecular subtypes in colorectal cancer differ by geographic region

4061

Background: The consensus molecular subtypes (CMS) have emerged as a novel classification in colorectal cancer (CRC). However, these subtypes, were mostly derived from a US/European population, and have scant data in other ethnic groups. This study aimed to demonstrate molecular subtypes of CRC across geographic regions. Methods: Formalin fixed paraffin embedded (FFPE) tissue from untreated patients with stage II-III colon cancer from Brazil, Canada, Mexico, Thailand, and the US were evaluated. Gene expression profiling was performed at the University of Texas MD Anderson Cancer Center using NanoString’s nCounter technology and an optimized classifier for FFPE. Results: A total of 366 samples were included in this study, evenly distributed between the 5 international sites. While the US population matched previously reported distributions, the distribution of CMS subtypes varied substantially by region (P < 0.0001). While CMS1 was still associated with right-sided tumors (P < 0.001) and deficient mismatch repair (dMMR) (P < 0.001), the prevalence varied between 8% in Brazil to 30% in Mexico. CMS2 was found vary from 14% in Mexico to 47% in Brazil. The metabolic CMS3 subtype was present in only 3% in Thailand, but as high as 19% in Brazil. CMS4 was confirmed to be associated with higher stage (P = 0.047), and the prevalence was lowest in Brazil (14%) compared to 44% and 49% in US and Mexico, respectively. Expansion of study cohort is ongoing. Conclusions: CMS subtype prevalence differs substantially by geographic region in CRC. These variations suggest that transcriptomic-defined disease biology in international populations may be more heterogeneous than previously appreciated. Further studies in global populations are required to validate and extend these findings, which may have important impact for novel therapeutic development.

Abstract IA27: Context-dependent role of KRAS in GI malignancies

Oncogenic Kras (Kras*) plays a key role in tumor maintenance and therapeutic resistance in several cancer types, although the precise biologic functions and mechanisms are not completely understood. We had previously shown in pancreatic ductal adenocarcinoma that some tumors underwent spontaneous relapse and were devoid of Kras* expression and downstream canonical MAPK signaling, instead acquiring amplification and overexpression of the transcriptional coactivator Yap1. Functional studies established the role of Yap1 and the transcriptional factor Tead2 in driving Kras*-independent tumor maintenance. In a second previous study, we developed a faithful colorectal cancer (CRC) mouse model and showed that Kras* drove invasion and maintenance in CRC. Here, utilizing this CRC mouse model, we demonstrate that KRAS* promotes a pronounced immune-suppressive profile distinguished by a predominance of myeloid-derived suppressor cells (MDSCs). We performed integrated transcriptomic and genomic analyses that identified IRF2 (Interferon Regulatory Factor 2) as a key KRAS* effector mediating immune suppression. IRF2 suppresses MDSC migration and infiltration in KRAS*-expressing CRC tumors by targeting the CXCL3/CXCR2 axis. We also observed that de novo resistance of KRAS*-expressing tumors to anti-PD1 therapy could be overcome by enforced IRF2 expression or by treatment with SX-682, a small-molecule CXCR2 antagonist. In addition, CRC patient tumors with higher IRF2 expression showed increased response to anti-PD1 therapy. This KRAS*-mediated immune-suppressive mechanism provides a framework for CRC patient selection and combination therapies to enhance the effectiveness of immune checkpoint blockade therapy in advanced disease.

Citation Format: Wen-Ting Liao, Michael J. Overman, Adam Boutin, Prasenjit Dey, Di Zhao, Guocan Wang, Jiexi Li, Zhengdao Lan, Jun Li, Xiaoying Shang, Ming Tang, Shan Jiang, Xingdi Ma, Peiwen Chen, Riham Katkhuda, Krittiya Korphaisarn, Deepavali Chakravarti, Qing Chang, Jianhua Zhang, Dipen M. Maru, Dean Y. Maeda, John A. Zebala, Scott Kopetz, Y. Alan Wang, Ronald A. DePinho. Context-dependent role of KRAS in GI malignancies [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr IA27.

Validation of HER2 Amplification as a Predictive Biomarker for Anti–Epidermal Growth Factor Receptor Antibody Therapy in Metastatic Colorectal Cancer

Purpose

HER2 amplification has been implicated in resistance to therapy with anti–epidermal growth factor receptor antibodies (anti-EGFRabs) in metastatic colorectal cancer (mCRC). The purpose of the study was to validate the predictive impact of HER2 amplification in mCRC.

Patients and Methods

We analyzed patients with RAS/BRAF wild-type mCRC across two distinct cohorts. In cohort 1 (n = 98), HER2 amplification was tested in tumor tissue using dual in situ hybridization ( HER2 amplification: HER2/CEP17 ratio, 2.0 or greater). Cohort 2 (n = 70) included 16 patients with HER2 amplification and 54 HER2 nonamplified controls identified by next-generation sequencing ( HER2 amplification: four or more copies) who had received prior anti-EGFRabs. The primary end point was progression-free survival (PFS) on treatment with anti-EGFRab therapy, which was estimated and compared using the Kaplan-Meier method and log-rank test.

Results

Median PFS in cohort 1 on anti-EGFRab–based therapy was significantly shorter in patients with HER2 amplification compared with HER2 nonamplified patients (2.8 v 8.1 months, respectively; hazard ratio [HR], 7.05; 95% CI, 3.4 to 14.9; P < .001). These findings were validated in cohort 2 (median PFS for HER2 amplified v nonamplified: 2.8 v 9.3 months, respectively; HR, 10.66; 95% CI, 4.5 to 25.1; P < .001). The median PFS on therapy without anti-EGFRabs was similar among HER2-amplified and nonamplified patients in both cohort 1 (9.7 v 11.1 months, respectively; HR, 1.01; 95% CI, 0.4 to 2.4; P = .97) and cohort 2 (9.6 v 11.3 months, respectively; HR, 1.21; 95% CI, 0.5 to 3.1; P = .66). In multivariable analyses, HER2 amplification emerged as a single independent predictor of poor PFS on anti-EGFRab therapy in both cohort 1 (HR, 6.48; 95% CI, 3.1 to 13.6; P < .001) and cohort 2 (HR, 10.1; 95% CI, 4.3 to 23.9; P < .001).

Conclusion

HER2 amplification in RAS/RAF wild-type mCRC seems to be a predictive biomarker for lack of efficacy of anti-EGFRab therapy. Screening patients with RAS/BRAF wild-type mCRC for HER2 amplification should be considered before anti-EGFRab treatment to guide therapy and to identify patients for early referral to clinical trials.

Dependency of Cholangiocarcinoma on Cyclin D-Dependent Kinase Activity

Cholangiocarcinoma (CCA) is a bile duct cancer with a very poor prognosis. Currently, there is no effective pharmacological treatment available for it. We showed that CCA ubiquitously relies on cyclin-dependent kinases 4 and 6 (CDK4/6) activity to proliferate. Primary CCA tissues express high levels of cyclin D1 and the specific marker of CDK4/6 activity, phospho-RB Ser780. Treatment of a 15-CCA cell line collection by pharmacological CDK4/6 inhibitors leads to reduced numbers of cells in the S-phase and senescence in most of the CCA cell lines. We found that expression of retinoblastoma protein (pRB) is required for activity of the CDK4/6 inhibitor, and that loss of pRB conferred CDK4/6 inhibitor-drug resistance. We also identified that sensitivity of CCA to CDK4/6 inhibition is associated with the activated KRAS signature. Effectiveness of CDK4/6 inhibition for CCA was confirmed in the three-dimensional spheroid-, xenograft-, and patient-derived xenograft models. Last, we identified a list of genes whose expressions can be used to predict response to the CDK4/6 inhibitor. Conclusion: We investigated a ubiquitous dependency of CCA on CDK4/6 activity and the universal response to CDK4/6 inhibition. We propose that the CDK4/6-pRB pathway is a suitable therapeutic target for CCA treatment.

Global differences in the prevalence of the CpG island methylator phenotype of colorectal cancer

Background

CpG Island Methylator Phenotype (CIMP) is an epigenetic phenotype in CRC characterized by hypermethylation of CpG islands in promoter regions of tumor suppressor genes, leading to their transcriptional silencing and loss of function. While the prevalence of CRC differs across geographical regions, no studies have compared prevalence of CIMP-High phenotype across regions. The purpose of this project was to compare the prevalence of CIMP across geographical regions after adjusting for variations in methodologies to measure CIMP in a meta-analysis.

Methods

We searched PubMed, Medline, and Embase for articles focusing on CIMP published from 2000 to 2018. Two reviewers independently identified 111 articles to be included in final meta-analysis. We classified methods used to quantify CIMP into 4 categories: a) Classical (MINT marker) Panel group b) Weisenberg-Ogino (W-O) group c) Human Methylation Arrays group and d) Miscellaneous group. We compared the prevalence of CIMP across geographical regions after correcting for methodological variations using meta-regression techniques.

Results

The pooled prevalence of CIMP-High across all studies was 22% (95% confidence interval:21–24%; I² = 94.75%). Pooled prevalence of CIMP-H across Asia, Australia, Europe, North America and South America was 22, 21, 21, 27 and 25%, respectively. Meta-regression analysis identified no significant differences in the prevalence of CIMP-H across geographical regions after correction for methodological variations. In exploratory analysis, we observed variations in CIMP-H prevalence across countries.

Conclusion

Although no differences were found for CIMP-H prevalence across countries, further studies are needed to compare the influence of demographic, lifestyle and environmental factors in relation to the prevalence of CIMP across geographical regions.

High Frequency of KRAS Codon 146 and FBXW7 Mutations in Thai Patients with Stage II-III Colon Cancer

Background: KRAS, NRAS, and BRAF gene mutations are the most clinically relevant and frequently reported in colorectal cancer (CRC). Although data on these genes are frequently reported in several counties, data specific to these genes among Thai population are scarce. The aim of this study was to investigate and identify molecular alterations associated with colon cancer in Thai population, and to determine the impact of these genetic aberrations on clinical outcome. Methods: DNA from 108 archived formalin-fixed, paraffin-embedded (FFPE) tissue samples that histologically confirmed adenocarcinoma of stage II-III colon cancer between 2010 and 2012 at Siriraj Hospital (Bangkok, Thailand) were extracted. Gene mutational analysis was performed by next-generation sequencing (NGS) using an Oncomine Solid Tumor DNA kit (Thermo Fisher Scientific, Inc., Waltham, MA, USA). Results: A total of 22 somatic gene mutations were detected. The mutation frequency observed in KRAS, NRAS, BRAF, PIK3CA, and FBXW7 mutations was 47.2%, 1.9%, 1.9%, 12%, and 14.8%, respectively. KRAS mutation codon 12, 13, 59, 61, 117, and 146 mutations were identified in 29.6%, 8.3%, 1.8%, 0.9%, 0.0%, and 8.3%, respectively. KRAS Exon 4 had better DFS compared with Exon 2 and 3. Conclusions: This study is the first to comprehensively report hotspot mutations using NGS in Thai colon cancer patients. The most commonly identified gene mutation frequencies among Thai patients (KRAS, NRAS, BRAF, TP53, and PIK3CA) were similar to the gene mutation frequencies reported in Western population, except for subgroup of KRAS codon 146 and FBXW7 mutations that had a slightly higher frequency.

KRAS-IRF2 Axis Drives Immune Suppression and Immune Therapy Resistance in Colorectal Cancer

The biological functions and mechanisms of oncogenic KRAS^G12D (KRAS^∗) in resistance to immune checkpoint blockade (ICB) therapy are not fully understood. We demonstrate that KRAS^∗ represses the expression of interferon regulatory factor 2 (IRF2), which in turn directly represses CXCL3 expression. KRAS^∗-mediated repression of IRF2 results in high expression of CXCL3, which binds to CXCR2 on myeloid-derived suppressor cells and promotes their migration to the tumor microenvironment. Anti-PD-1 resistance of KRAS^∗-expressing tumors can be overcome by enforced IRF2 expression or by inhibition of CXCR2. Colorectal cancer (CRC) showing higher IRF2 expression exhibited increased responsiveness to anti-PD-1 therapy. The KRAS^∗-IRF2-CXCL3-CXCR2 axis provides a framework for patient selection and combination therapies to enhance the effectiveness of ICB therapy in CRC.

FBXW7 missense mutation: a novel negative prognostic factor in metastatic colorectal adenocarcinoma

Background

FBXW7 functions as a ubiquitin ligase tagging multiple dominant oncogenic proteins and commonly mutates in colorectal cancer. Data suggest missense mutations lead to greater loss of FBXW7 function than other gene aberrations do. However, the clinicopathologic factors and outcomes associated with FBXW7 missense mutations in metastatic colorectal cancer (mCRC) have not been described.

Methods

Data were obtained from mCRC patients whose tumors were evaluated by next-generation sequencing for hotspot mutations at The University of Texas MD Anderson Cancer Center. Alterations in FBXW7 were identified, and their associations with clinicopathologic features and overall survival (OS) were evaluated.

Results

Of 855 mCRC patients, 571 had data on FBXW7 status; 43 (7.5%) had FBXW7 mutations, including 37 with missense mutations. R465C mutations in exon 9 were the most common missense mutations (18.6%). PIK3CA mutations were associated with FBXW7 missense mutations (p=0.012). On univariate analysis, patients with FBXW7 missense mutations had significantly worse OS (median 28.7 mo) than those with wild-type FBXW7 (median 46.6 mo; p=0.003). On multivariate analysis including other known prognostic factors such as BRAF mutations, FBXW7 missense mutations were the strongest negative prognostic factor for OS (hazard ratio 2.0; p=0.003).

Conclusions

In the largest clinical dataset of mCRC to date, FBXW7 missense mutations showed a strong negative prognostic association.

Abstract A055: RSPO3 overexpression is a characteristic feature of signet ring gastrointestinal malignancies

Introduction: The Wnt/β-catenin pathway is critical in the pathogenesis of many gastrointestinal malignancies, and, when disrupted, promotes aberrant cell proliferation and loss of cell stemness. Mutations in APC are the most common etiology of Wnt/β-catenin signaling dysfunction in colorectal (CRC) cancers. However, in the approximately 20% of CRCs that are APC wild-type, abnormalities in cell-surface genes like RNF43 and RSPO drive pathologic Wnt/β-catenin activity. We sought to characterize further gastrointestinal tumors harboring RSPO alterations. Methods: Under an IRB-approved protocol at MD Anderson, tumors from 665 patients with metastatic CRC at MD Anderson were evaluated by next-generation sequencing for APC mutations and for the presence of signet ring cells. Mutation profiling and gene expression data from the TCGA (www.cbioportal.org) were analyzed in 223 patients with CRC for APC mutations and for RSPO overexpression for a correlation using a Fisher’s exact test. RNA extracted from 19 separate frozen tumors from patients with confirmed signet ring metastatic CRC was next analyzed by RNA-seq for the presence for RSPO fusions and for RSPO gene expression levels. In a validation set of FFPE samples derived from patients with signet ring metastatic CRC or signet ring gastric adenocarcinomas, RSPO3 gene expression was analyzed using RT-PCR in a CLIA-validated setting (Oncomed Pharmaceuticals). Results: APC mutations were detected less frequently in signet ring CRC tumors relative to non-signet ring counterparts (18% vs. 56%, P&lt; .001). RSPO overexpression was also observed more commonly in APC wild-type CRC tumors (16% vs. 7%, P= .04). Given these associations, we investigated further a correlation between signet ring adenocarcinomas and RSPO overexpression. Gene expression analysis of signet ring CRC tumors revealed high RSPO3 expression in 13 of 19 cases (68%). Here, a trend towards higher RSPO3 expression was observed in tumors with &gt; 50% signet ring cells present (P=.20). In a validation cohort of patients with signet ring adenocarcinomas, RSPO3 overexpression was noted in 20/38 (52%) CRCs and 21/22 (96%) gastric adenocarcinomas. RSPO fusions were detected in 0 of 19 patients with signet ring CRC analyzed by RNA-seq. Conclusions: In molecularly specified populations of patients with colorectal and gastric malignancies, RSPO3 overexpression is detected in high frequencies in signet ring adenocarcinomas. Given the cell surface localization of RSPO3 and the importance of Wnt/β-catenin signaling in the tumorigenesis of gastrointestinal malignancies, our findings warrant further evaluation for anti-RSPO3 therapies as novel treatment options for patients with signet ring adenocarcinomas.

Citation Format: Van Morris, Alexey Sorokin, Mariela Blum, Krittiya Korphaisarn, Jeannelyn Estrella, Leonardo Faoro, Min Wang, Stanley Hamilton, Ann M. Kapoun, Scott Kopetz. RSPO3 overexpression is a characteristic feature of signet ring gastrointestinal malignancies [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 A055.

Arginine methylation of EGFR: a new biomarker for predicting resistance to anti-EGFR treatment

Arginine methylation of the epidermal growth factor receptor (meEGFR) increases the binding affinity of EGFR ligands and is reported to have a role in predicting response to anti-EGFR agents. This study investigated the predictive impact of meEGFR in metastatic colorectal cancer (mCRC) patients treated with anti-EGFR agents. Two patient cohorts were evaluated. Cohort 1 consisted of mCRC patients with documented disease progression following anti-EGFR treatment. Circulating tumor cells (CTCs) were isolated and distinguished based on CD45^- and Epcam⁺. Cohort 2 consisted of formalin fixed paraffin-embedded (FFPE) blocks from a prospective cohort. meEGFR in both cohorts was identified by positive staining for me-R198/200 EGFR signal. CTCs were identified in 30 out of 47 cases in cohort 1. Of those 30, meEGFR-CTCs were identified in 19 cases. Mean total meEGFR-CTCs counts was 2.3 (range 0-30) cells per 7.5 ml. There was no association between meEGFR-CTCs and clinic-pathological-molecular features. In RAS^wt/BRAF^wt patients with high levels of meEGFR-CTCs ratio (≥ 0.23) had significantly inferior PFS with anti-EGFR treatment (HR = 3.4, 95% CI 1.5-7.9, P = 0.004). By contrast, high levels of meEGFR in the untreated tumor tissues had no correlation with anti-EGFR treatment duration in cohort 2. Therefore, meEGFR-CTCs may have the potential to serve as a "liquid biopsy" biomarker to predict anti-EGFR treatment efficacy.

Genomic analysis of exceptional responder to regorafenib in treatment-refractory metastatic rectal cancer: a case report and review of the literature

We present the case of a 53-year-old male with metastatic rectal cancer who was treatment resistant to FOLFOX and FOLFOXIRI. Due to a Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation, regorafenib was given in the third line setting. Surprisingly, the patient had a prolonged partial response that lasted 27 months. Mutational status was extensively evaluated to identify potential alterations that might play a role as predictive markers for this unusual event. A poorly characterized but nontransforming mutation in Fms-like tyrosine kinase 4 (FLT4) was present in the tumor. Prior to and at the time of clinical progression, we found amplification of fibroblast growth factor receptor 1 (FGFR1) and epidermal growth factor receptor (EGFR), loss of the FLT4 mutation, and gain of KIT proto-oncogene receptor tyrosine kinase (KIT) G961S suggesting potential roles in acquired resistance.

Arginine methylation of EGFR in circulating tumor cells: A new biomarker for predicting resistance to anti-EGFR agents

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Background: Arginine methylation of the epidermal growth factor receptor (meEGFR) increases binding affinity of EGF and other EGFR ligands, reduces the efficacy of anti-EGFR agents in vivo, and is reported to have a role in predicting response to anti-EGFR agents. This study aimed to investigate the predictive impact of meEGFR in metastatic colorectal cancer (mCRC) patients (pts) treated with anti-EGFR agents using blood-based testing. Methods: 15 mL of blood were collected from mCRC pts with documented disease progression following anti-EGFR treatment (Rx). Circulating tumor cells (CTCs) were isolated using antibody (ab)-independent micro-fluidic cassette-based technology (Parsortix system), which separates CTCs on the basis of size and deformability. CTCs were identified based on negative staining for CD45ab and positive staining for EpCAMab. meEGFR was identified based on positive staining for me-R198/200ab on CTCs. Associations between meEGFR-CTCs and total CTCs with progression free survival (PFS) were determined by Kaplan-Meier method and compared by the log-rank test. Results: A total of 47 mCRC pts were prospectively included in this study. CTCs were identified in 30 out of 47 cases (64%). Of those 30, meEGFR-CTCs were identified in 19 cases (63%). Mean total CTCs and meEGFR-CTCs counts were 3.6 (range 0-52) and 2.3 (range 0-30) cells per 7.5ml, respectively. There was no association between meEGFR-CTCs and clinic-pathological features (age, sex, tumor site & grade), line of anti-EGFR Rx, previous irinotecan used, or NRAS, BRAF, PIK3CA, and MSI status. However, in RASwt/BRAFwtmCRC pts, high levels of meEGFR ratio (defined as > 0.25 meEGFR-CTCs per total CTCs) was associated with significantly inferior PFS with anti-EGFR Rx (median PFS 5.4 mo vs. 8 mo, HR 3.4, 95% CI of 1.5-7.9, P = 0.004). By contrast, high levels of total CTCs ( > 3 cells/per 7.5 ml) had no impact on PFS with anti-EGFR Rx. Conclusions: We have successfully isolated CTCs from mCRC pts’ blood using Parsortix system. Elevated levels of arginine methylated EGFR is associated with a shorter PFS with anti-EGFR-based Rx. Assessment of meEGFR-CTCs may provide a “liquid biopsy” biomarker for reduced efficacy from anti-EGFR Rx.

Efficacy of ginger for prophylaxis of chemotherapy-induced nausea and vomiting in breast cancer patients receiving adriamycin-cyclophosphamide regimen: a randomized, double-blind, placebo-controlled, crossover study

PURPOSE

The purpose of this study is to determine the efficacy of ginger for reducing chemotherapy-induced nausea and vomiting (CINV) in breast cancer patients receiving adriamycin and cyclophosphamide (AC) regimens.

METHODS

We enrolled breast cancer patients receiving AC who experienced moderate to severe nausea or vomiting during the first chemotherapy cycle. Subjects were randomized to receive a 500-mg ginger capsule or placebo twice a day for 5 days starting on the first day of the second AC cycle and were switched to the other treatment in the third cycle. All participants also received ondansetron and dexamethasone for CINV prophylaxis. Nausea severity was recorded once a day during the first 5 days of each cycle. The primary outcome was reduction in nausea score.

RESULTS

Thirty-four subjects (68 cycles of AC) were enrolled. Mean (range) maximum nausea score in the first AC cycle was 58 (40-90). Thirty-three subjects (97 %) received the same AC doses in the second as in the third cycle. Mean (±standard error) maximum nausea scores in patients receiving ginger and placebo were 35.36 (±4.43) and 32.17 (±3.71), respectively. The difference in mean maximum nausea scores was 3 (95 % confidence interval, -3 to 9; P = 0.3). There were no significant differences between ginger and placebo in terms of vomiting incidence and severity, rescue medication use, chemotherapy compliance, and adverse events.

CONCLUSIONS

Ginger (500 mg) twice daily was safe, but conferred no additional benefit in terms of reducing nausea severity in breast cancer patients receiving AC and ondansetron and dexamethasone for CINV prophylaxis.

Signet ring cell colorectal cancer: Genomic insights into a rare subpopulation of colorectal adenocarcinoma

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Background: Colorectal signet ring cell carcinoma (SRCC) has been shown to be associated with advanced tumor stage at presentation and worse outcomes. Due to the rarity of this subtype, 1% of all colorectal adenocarcinoma (CRC), little is known about its molecular characteristics. We aimed to characterize the molecular alterations of this subgroup. Methods: Metastatic CRC (mCRC) patients (pts) with signet ring cell (SC) histology who had tumors evaluated with next generation sequencing between February 2009 and November 2015 were reviewed. SC mCRC were classified into 2 groups; SRCC (>50% of signet cells) and adenocarcinoma (AC) with SC component. Genomic alterations, microsatellite instability (MSI) and CpG island methylator phenotype (CIMP) status noted in SC mCRC were compared to non-SC mCRC pts from the Assessment of Targeted Therapies Against Colorectal Cancer program at MD Anderson Cancer Center using Pearson’s χ 2 test. Results: A total of 665 mCRC pts were included in this study. 93 pts (14%) had SC histology of which 30 (32.3%) pts were SRCC. The Table below shows key cancer genes mutation frequencies. Conclusions: Colorectal SRCC has distinct molecular features compared with non-SC and AC with SC component CRC. The frequencies of KRAS, PIK3CA and APC mutations were lower than the frequencies reported in non-SC CRC. SRCC was not associated with MSI-H or CIMP-H tumor in this study. Further studies on identification of activated pathways underlying this worse prognosis and potential therapeutic targets are required. [Table: see text]

BRAF-Directed Therapy in Metastatic Colorectal Cancer

Activating BRAF (V-raf murine sarcoma viral oncogene homolog B) mutations occur in approximately 5% to 10% of patients with metastatic colorectal cancer, mostly V600E mutation, and it is associated with distinct clinical and pathological features. To date, there are no approved treatments to target this mutation. BRAF inhibitor monotherapy has limited efficacy, in contrast to metastatic melanoma. Combination strategies that block not only BRAF mutated kinase but other alternative pathways are ongoing and have demonstrated improved activity. This review aims to provide data about new strategies to target to BRAF gene mutation in metastatic colorectal cancer.

Deficient DNA mismatch repair is associated with favorable prognosis in Thai patients with sporadic colorectal cancer

AIM: To determine the prognostic significance of deficient mismatch repair (dMMR) and BRAF V600E in Thai sporadic colorectal cancer (CRC) patients.

METHODS: We studied a total of 211 out of 405 specimens obtained from newly diagnosed CRC patients between October 1, 2006 and December 31, 2007 at Siriraj Hospital, Mahidol University. Formalin-fixed paraffin-embedded blocks of CRC tissue samples were analyzed for dMMR by detection of MMR protein expression loss by immunohistochemistry or microsatellite instability using polymerase chain reaction (PCR)-DHPLC. BRAF V600E mutational analysis was performed in DNA extracted from the same archival tissues by two-round allele-specific PCR and analyzed by high sensitivity DHPLC. Associations between patient characteristics, MMR and BRAF status with disease-free survival (DFS) and overall survival (OS) were determined by Kaplan-Meier survival plots and log-rank test together with Cox’s proportional hazard regression.

RESULTS: dMMR and BRAF V600E mutations were identified in 31 of 208 (14.9%) and 23 of 211 (10.9%) tumors, respectively. dMMR was more commonly found in patients with primary colon tumors rather than rectal cancer (20.4% vs 7.6%, P =0.01), but there was no difference in MMR status between the right-sided and left-sided colon tumors (20.8% vs 34.6%, P = 0.24). dMMR was associated with early-stage rather than metastatic disease (17.3% vs 0%, P = 0.015). No clinicopathological features such primary site or tumor differentiation were associated with the BRAF mutation. Six of 31 (19.3%) samples with dMMR carried the BRAF mutation, while 17 of 177 (9.6%) with proficient MMR (pMMR) harbored the mutation (P = 0.11). Notably, patients with dMMR tumors had significantly superior DFS (HR = 0.30, 95%CI: 0.15-0.77; P = 0.01) and OS (HR = 0.29, 95%CI: 0.10-0.84; P = 0.02) compared with patients with pMMR tumors. By contrast, the BRAF V600E mutation had no prognostic impact on DFS and OS.

CONCLUSION: The prevalence of dMMR and BRAF V600E in Thai sporadic CRC patients was 15% and 11%, respectively. The dMMR phenotype was associated with a favorable outcome.

Association between Pathological Complete Response and Outcome Following Neoadjuvant Chemotherapy in Locally Advanced Breast Cancer Patients

PURPOSE

We aimed to determine the rate of pathological complete response (pCR), clinicopathological factors associated with pCR, and clinical outcomes following neoadjuvant chemotherapy in locally advanced breast cancer.

METHODS

Medical records of patients who had undergone neoadjuvant chemotherapy for breast cancer between January 2007 and September 2011 were retrospectively reviewed, and the pCR rates were calculated according to three sets of criteria: the National Surgical Adjuvant Breast and Bowel Project (NSABP), the MD Anderson Cancer Center (MDACC), and the German Breast Group (GBG). Tumors were classified as luminal A like, luminal B like, human epidermal growth factor receptor 2 (HER2), or triple-negative. pCR and clinical outcome, including overall survival (OS) and disease-free survival (DFS) rates were analyzed at the median follow-up of 54.2 months.

RESULTS

Of a total of 179 patients who had received neoadjuvant chemotherapy, 167 patients (93.3%) had locally advanced breast cancer and 12 patients (6.7%) had early-stage breast cancer. The majority of patients (152 patients, 89.4%) received anthracycline-based neoadjuvant chemotherapy. The objective clinical response rate was 61.5%, comprising clinical partial response in 5.5% and clinical complete response in 3.9% of patients. Twenty-one (11.7%), 20 (11.2%), and 17 patients (9.5%) achieved pCR according to NSABP, MDACC, and GBG definitions, respectively. pCR rates, as defined by NSABP, according to breast cancer subtype were 4.4%, 9.7%, 24.2%, and 19.2% in luminal A like, luminal B like, HER2, and triple-negative subtypes, respectively. Patients who achieved pCR had significantly better DFS (5-year DFS rates, 80% vs. 53%, p=0.030) and OS (5-year OS rates, 86% vs. 54%, p=0.042) than those who did not.

CONCLUSION

The pCR rate following neoadjuvant chemotherapy for breast cancer in Thai women attending our institution was 11.7%; pCR was more frequently observed in HER2 and triple-negative breast tumor subtypes. Patients who achieved pCR had significantly improved survival.

Effectiveness of direct observation and supervision at out-patient setting on improving clinical skills of medical students

BACKGROUND

Direct observation and supervision (DOS) is the teaching method where a mentor provides direct observation during patient encounter and provides feedback to the learner in real-time manner Previous studies showed that DOS improves patient care and trainees' clinical skill but is difficult to implement.

OBJECTIVE

To evaluate students' performance and attitude after implementing DOS to the 5th year medical students.

MATERIAL AND METHOD

DOS was introduced for the whole class of the 5th year medical students throughout the year at out-patient setting department of Medicine, Siriraj Hospital in 2012. DOS sessions were provided during the first few patients 'encounters. Students 'performances at out-patients clinics were ratedfor other 8 subsequence sessions. The average score were compared to the 5th year medical students in 2011 (Conventional technique, CT).

RESULTS

Two hundred andforty six students were supervised in DOS group. The mean score ofstudents who received DOS was significantly higher than CT group with the score of 8.2 compared to 7.9, respectively (p < 0.001). With respect to students'satisfaction, 75% of students rated DOS as a learning method with high to very high benefit.

CONCLUSION

DOS method is feasible to implement and could improve student's performance with good satisfaction from medical students.

Prevalence of BRAF gene mutation in Thai sporadic colorectal cancer patients

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Background: The role of BRAF gene mutation has been studied for its association with prognosis of colorectal cancer (CRC). The prevalence was reported 10-15% in Caucasian patients. However, there is no existing data in Thai patients. This study aimed to determine the prevalence of BRAF V600E mutation, association with various clinicopathological features and outcome in Thai sporadic CRC patients. Methods: DNA was extracted from randomly selected formalin-fixed paraffin-embedded tumor blocks of CRC patients with stage I-IV receiving surgery of the primary tumors at Siriraj Hospital between 2006 and 2007. BRAF V600E mutation was performed by two-round allele-specific PCR and analysis using high sensitivity DHPLC. The association between patient characteristics and BRAF status with overall survival (OS) and disease free survival (DFS) were explored by Kaplan-Meier estimation and log-rank test together with Cox’s proportional hazard regression. Results: BRAF V600E mutation was identified in 7 out of 188 patients (3.7%). Four patients were female. There were more likely to found in tumors on the left side (n=4) compared with right side (n=2) and rectum (n=1). All patients with mutation had stage I-III diseases; one with stage I and 3 with stage II and III each. Four had moderately differentiated tumors. Six patients had neither lymphovascular nor perineural invasion. Patients with mutation seemed to have better survival. In multivariate analysis, BRAF mutation did not have major prognostic value regarding DFS or OS. Conclusions: The prevalence of BRAF V600E mutation in Thai sporadic CRC was 3.7% which was lower than what reported in Caucasian patients. Further study with larger number of patients is warranted to determine whether BRAF mutation has significant prognostic value.