Long-term response with the atypical reaction to nivolumab in microsatellite stability metastatic colorectal cancer: A case report

Immunotherapy has become an integral part of a comprehensive treatment approach to metastatic colorectal cancer (mCRC). Nivolumab (Opdivo) is a human immunoglobulin G4 monoclonal antibody that blocks the interaction between the programmed cell death 1 (PD-1) receptor and its ligands 1/2 (PD-L1/PD-L2), leading to inhibition of T-cell proliferation, cytokine secretion, and enhanced immune response. The US Food and Drug Administration (FDA) has approved this drug for use in high microsatellite instability (MSI-high)/deficiencies in mismatch repair (dMMR) advanced CRC patients. However, its efficacy is extremely limited in microsatellite stability (MSS)/mismatch repair proficient (pMMR) patients. We report a case of a 42-year-old man diagnosed with MSS/pMMR mCRC who has achieved a durable response to nivolumab after a progression under chemotherapy with antiangiogenic treatment. We observed for the first time an atypical response after 8 months of nivolumab treatment, with the regression of previous primary pulmonary lesions and the presence of new para-aortic lymph node lesions. This report demonstrates that a subset of pretreated mCRC patients with the MSS/pMMR phenotype may benefit from nivolumab and these patients need more attention.

Role of TGF-β signaling in the mechanisms of tamoxifen resistance

The transforming growth factor beta (TGF-β) signaling pathway plays complex role in the regulation of cell proliferation, apoptosis and differentiation in breast cancer. TGF-β activation can lead to multiple cellular responses mediating the drug resistance evolution, including the resistance to antiestrogens. Tamoxifen is the most commonly prescribed antiestrogen that functionally involved in regulation of TGF-β activity. In this review, we focus on the role of TGF-β signaling in the mechanisms of tamoxifen resistance, including its interaction with estrogen receptors alfa (ERα) pathway and breast cancer stem cells (BCSCs). We summarize the current reported data regarding TGF-β signaling components as markers of tamoxifen resistance and review current approaches to overcoming tamoxifen resistance based on studies of TGF-β signaling.

Impact of estrogen receptor α on the tamoxifen response and prognosis in luminal-A-like and luminal-B-like breast cancer

The luminal-A-like and luminal-B-like breast cancer groups have distinct biological features that lead to differences in the treatment response and clinical outcome. The aim of this study was to examine the value of the distribution pattern of ERα expression, ESR1 SNPs as well as ESR1 mRNA expression in predicting tamoxifen response and survival in patients with luminal-A-like and luminal-B-like breast cancer. A total of 135 patients with both subtypes were stratified into two groups depending on the tamoxifen response: tamoxifen-resistant patients (TR) and tamoxifen-sensitive patients (TS). ESR1 mRNA expression was measured by real-time quantitative reverse transcription-PCR. Three polymorphisms of ESR1 (rs2077647, rs2228480 and rs1801132) were genotyped using a TaqMan assay. The distribution pattern of ERα expression was analyzed immunohistochemically using the visual assessment of staining. The primary endpoint was progression-free survival (PFS). There was a significant decrease in ESR1 mRNA expression level in the TR group when compared to the TS group among patients with luminal-B-like subtype (P = 0.038). ESR1 2014AA mutant genotype of rs2228480 was more prevalent in the TR patients with luminal-B-like subtype than the TS group (P = 0.045). In the luminal-A-like group, tamoxifen-resistant tumors were more frequently heterogeneous for ERα expression than tamoxifen-sensitive tumors (P = 0.016). Multivariate analysis showed a strong association of lymph node status and the distribution pattern of ERα expression with tamoxifen responsiveness in this cohort of patients. In addition, a luminal-A-like patients with the heterogeneous ERα expression had a significantly shorter PFS time than those with the homogeneous ERα (P = 0.013). These results indicate that the heterogeneous expression of ERα is an accurate predictor of tamoxifen response and survival in luminal-A-like breast cancer patients. ESR1 rs2228480 may act as a marker with a high prognostic potential in luminal-B-like tumors.

Predictive value of vascular endothelial growth factor receptor type 2 in triple-negative breast cancer patients treated with neoadjuvant chemotherapy

The identification of informative biomarkers that could predict the treatment response is particularly important in the triple-negative (TN) breast cancer, which is characterized by biological diversity. The aim of this study was to investigate the impact of vascular endothelial growth factor receptor (VEGFR2) expression and its gene polymorphisms on pathologic complete response (pCR) to neoadjuvant chemotherapy (NCT) in Russian patients with TN breast cancer. We performed a retrospective analysis of 70 women with operable TN breast cancer, who underwent NCT with 5-fluorouracil, adriamycin, and cyclophosphamide (FAC) or cyclophosphamide, adriamycin, and capecitabine (CAX) between 2007 and 2013. VEGFR2 expression was evaluated before NCT by immunohistochemistry. TaqMan SNP assays were used for genotyping KDR - 604T>C (rs2071559) and KDR 1192G>A (rs2305948) polymorphisms. The pCR was used as an end-point in the treatment efficacy analysis. In the univariate analysis, the pCR rate was strongly associated with young age (P = 0.004), high Ki67 expression (P = 0.012), lymph node negativity (P = 0.023) as well as with positive VEGFR2 expression (P = 0.019) and the CAX regimen (P = 0.005). In the multivariate analysis, only patient's age (P = 0.005) and pre-NCT VEGFR2 expression (P = 0.048) remained significant predictors of pCR. The pCR rate was higher in the CAX-treated patients than that in the FAC-treated patients (P = 0.005). Our results revealed that - 604TT genotype of rs2071559 and age < 50 years were correlated with a pCR in the CAX-treated patients. VEGFR2 expression in pre-NCT tumors and KDR gene polymorphism can be considered as additional predictive molecular markers of pCR in Russian TN breast cancer patients treated with NCT.

Abstract A26: The distribution pattern of ERα expression, VEGFR2 expression level and its genetic variation as potential biomarkers for tamoxifen resistance

Background. The crosstalk between estrogen receptor alpha (ERα) and growth factor receptors is an essential part of tamoxifen resistance and the vascular endothelial growth factor/ tyrosine kinase domain receptor (VEGF/KDR) signaling pathway is clinically significant in the mechanisms of this resistance. The aim of the present study was to analyze the association of distribution pattern of ERα expression, VEGFR2 expression level, ESR1 and KDR single nucleotide polymorphisms (SNPs) with tamoxifen response in hormone receptor-positive primary breast cancer.

Material and methods. Formalin-fixed paraffin-embedded and fresh frozen breast cancer tissue of the primary tumor was obtained from 97 hormone receptor-positive breast cancer patients treated with adjuvant tamoxifen at the Tomsk Cancer Research Institute. The distribution patterns of ERα expression and Ki-67 protein expression were determined by immunohistochemistry. The quantitative expression levels of VEGFR2 (CD309) and p-Akt473 was measured using a flow cytometry. TaqMan SNP assays were used for genotyping ESR1+30T&gt;C (rs2077647), ESR1 2014G&gt;A (rs2228480), KDR-604T&gt;C (rs2071559) and KDR 1192G&gt;A (rs2305948) polymorphisms. Progression-free survival (PFS) was used as end-point for survival analyses.

Results. Patients who did not benefit from tamoxifen treatment (tamoxifen resistance group -TR) showed significantly higher heterogeneous ERα expression than tamoxifen sensitive patients (TS; 81.1% and 58.3% respectively, P = 0.021). We found that ESR12014A mutant allele carriers were more prevalent in TR patients than in TS group (26.3% vs. 8.0%, respectively, P = 0.009). Similarly, the KDR -604T allele of rs2071559 was statistically significant related with tamoxifen resistance (P = 0.034). However, the KDR 1192G allele of rs2305948 were significantly less common in the tamoxifen progressive group compared to the tamoxifen sensitive patients (38.0% vs. 90.0%, respectively, P = 0.035). In addition, the variant homozygote KDR 1192GG (vs. AA) of rs2305948 was associated with VEGFR2 expression (r = -0.524, p = 0.012). VEGFR2 expression levels also showed borderline significant correlation with p-Akt473 expression (r = 0.368, p = 0.070). The Kaplan-Meier survival analysis demonstrated a significant relationship of heterogeneous distribution of ERα expression with poor survival of tamoxifen treated patients (log-rank P = 0.009). Moreover, the PFS for the patients with the KDR -604TT genotypes of rs2071559 were worse than for the patients with the CC genotype (log-rank P = 0.123).

Conclusion. The distribution pattern of ERα expression, VEGFR2 expression level and its genetic variation can serve as potential predictors for hormone receptor-positive breast cancer patients treated with adjuvant tamoxifen and thus provide more information for optimizing patient's selection to tamoxifen adjuvant therapy.

Citation Format: Nataliya Babyshkina, Sergey Vtorushin, Stanislav Patalyak, Tatyana Dronova, Elena Slonimskaya, Nadejda Cherdyntseva. The distribution pattern of ERα expression, VEGFR2 expression level and its genetic variation as potential biomarkers for tamoxifen resistance. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A26.

Abstract 562: Impact of ERα expression status and ESR1 genetic variation on progression in tamoxifen-treated breast cancer patients

Background. Resistance to tamoxifen remains a major clinical challenge in the treatment of breast cancer. The aim of this study was to evaluate the influence of the intensity and the pattern of estrogen receptor α (ERα) expression and common single nucleotide polymorphisms (SNP) in the estrogen receptor 1 gene (ESR1, rs2228480:2014G&gt;A; rs2077647:+30T&gt;C) on disease progression in breast cancer patients who received adjuvant tamoxifen.

Material and methods. Formalin-fixed paraffin-embedded tumor tissue samples were retrospectively collected from 61 patients, who had distant metastasis versus distant metastasis-free breast cancers (n = 37 versus n = 24, respectively, with a 9-year follow-up). Protein expression of ER, PR and HER2 were assessed by immunohistochemistry. Real-time polymerase chain reaction analysis was used to determine the ESR1 SNPs.

Results. We found that the heterogeneous distribution of ERα was statistically significant related with a low expression level and intensity of ERα in tumor tissue samples (p=0.002 and p=0.0002, respectively). In addition, the level and intensity of ERα expression was lower in patients with distant metastasis compared to distant metastasis-free cases, but these differences were not significant (P&gt;0.05). Nonetheless, the ESR1 2014A allele was associated with a heterogeneous distribution of ERα expression (p=0.02). We showed the higher risk of distant metastasis development for the patients carrying the ESR1 2014A mutant allele compared with women with ESR1 2014G variant (p=0.04).

Conclusion. These data suggest that the expression level and intensity of ERα with ESR1 2014G&gt;A genetic variation could be a useful molecular markers for predicting tamoxifen treatment prognosis in breast cancer patients.

Citation Format: Nataliya Babyshkina, Sergey Vtorushin, Stanislav Patalyak, Tatyana Dronova, Elena Slonimskaya, Nadejda Cherdyntseva. Impact of ERα expression status and ESR1 genetic variation on progression in tamoxifen-treated breast cancer patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 562. doi:10.1158/1538-7445.AM2014-562