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.

Pathogenicity Reclassification of Genetic Variants Related to Early-Onset Breast Cancer among Women of Mongoloid Origin

BACKGROUND

Germline alterations in BRCA1, BRCA2, and other genes are responsible for early-onset breast cancer. However, up to 20% of molecular tests report genetic variant of unknown significance (VUS) or novel variants that have never been previously described and their clinical significance are unknown. This study aimed to reclassify variant of unknown significance (VUS) or novel variants by using the ActiveDriveDB database that annotates variants through the lens of sites of post-translational modifications (PTM).

METHODS

Our study included thirty-eighth young Buryat BC patients, belonging to the Mongoloid race and anthropologically to the Central Asia. Genomic DNA was extracted from the peripheral blood lymphocytes using the phenol/chloroform method. DNA library were prepared using the Hereditary Cancer SolutionTM kit (Sophia GENETICS, Switzerland) to cover 27 genes, such as ATM, APC, BARD1, BRCA1, BRCA2, BRIP1, CDH1, CHEK2, EPCAM, FAM175A, MLH1, MRE11A, MSH2, MSH6, MUTYH, NBN, PALB2, PIK3CA, PMS2, PMS2CL, PTEN, RAD50, RAD51C, RAD51D, STK11, TP53, and XRCC2. Paired-end sequencing (2 x 150 bp) was conducted using NextSeq 500 system (Illumina, USA).

RESULTS

We re-examined 135 rare variants (41 VUS, 25 conflicting, 64 benign and 5 new variants). We identified 10 out of 135 (7.4%) mutations that affected the sites of post-translational modification in proteins. Of 135 rare mutations, 1 benign variant was reclassified as network-rewiring - motif loss mutation, 3 VUS and 1 new variant were reclassified as distal PTM- mutations, 2 new and 1 benign variant were classified as proximal PTM- mutations and 1 benign and 1 conflicting variant were classified as direct PTM- mutations.

CONCLUSIONS

For the first time, 7.4% (10 out of 135) of mutations that affected the sites of post-translational modification in proteins were identified among early-onset breast cancer women of Mongoloid origin.

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.

New germline mutations in BRCA1, ATM, MUTYH, and RAD51D genes in Tuvans early-onset breast cancer patients

BACKGROUND

In Russia, more than 50,000 women are diagnosed with breast cancer (BC) every year. Russia is a multinational country - about 200 ethnic groups live on its territory. Khakass, Buryats, Tuvans and other ethnic groups show higher rate of increase in BC incidence and a younger age of first diagnosed BC compared to Caucasian ethnicities. We focused on Tuvan ethnic group to find specific genetic aberrations associated with BC. There are no BC prevention models as well as standards for the treatment of inherited BC in Tuvans. In this context, the search for genetic markers of early cancer detection and the development of criteria for therapy response are relevant.

AIM

To identify hereditary mutations in BC-associated genes in Tuvan women.

MATERIALS AND METHODS

24 patients with early-onset BC (range, 25 to 46 years) were enrolled in the study. Genomic DNA isolated from blood samples was used to prepare libraries using a capture-based target enrichment kit covering 27 genes (ATM, APC, BARD1, BRCA1, BRCA2, BRIP1, CDH1, CHEK2, EPCAM, FAM175A, MLH1, MRE11A, MSH2, MSH6, MUTYH, NBN, PALB2, PIK3CA, PMS2, PMS2CL, PTEN, RAD50, RAD51C, RAD51D, STK11, TP53 and XRCC2). Next-generation sequencing was performed using the Illumina NextSeq500 System.

RESULTS

In our study, one pathogenic mutation was detected in BRCA1 (rs80357868) gene (prevalence of 4%, 1/24). We identified the truncating 3875_3878delGTCT mutation of BRCA1 gene in Tuvans BC patient aged 34 years. We also detected three mutations that were probably damaging by PolyPhen2 and/or deleterious by SIFT in ATM (rs781023264), MUTYH (rs199840380) and RAD51D (rs145309168) genes.

CONCLUSION

To the best of our knowledge, this is the first report that describes the highly pathogenic variant in the BRCA1 gene (rs80357868) and possibly damaging (PolyPhen2) germline variants in the ATM (rs781023264), MUTYH (rs199840380) and RAD51D (rs145309168) genes in young Tuvans BC patient.

New germline mutations in non-BRCA genes among breast cancer women of Mongoloid origin

In accordance with the Asian BRCA Consortium data, there is a significant difference in incidence rate of breast cancer depending on age, as well as spectrum and prevalence of BRCA1/2 mutations between Mongoloid (East Asian) and Caucasoid (European) people. However, European strategies to identify familial BC are still applied to the Asian population, including Russian Mongoloids (Khakas, Buryats, Tyvans and Yakuts and others). The main purpose of the study was to identify molecular changes associated with hereditary BC in Russian Mongoloid BC patients (Buryats). Thirty-nine patients were included in the study. Genomic DNA extracted from lymphocytes was used to prepare DNA-libraries. Target sequencing was designed to cover 27 genes, such as ATM, APC, BARD1, BRCA1, BRCA2, BRIP1, CDH1, CHEK2 and others. Paired-end sequencing (2 × 150 bp) was conducted on a NextSeq 500 system (Illumina, USA). Three pathogenic mutations in non-BRCA genes were found (prevalence of 8%). The pathogenic mutations were found in the RAD51D and PTEN genes. The pathogenic variant in the RAD51D gene (rs137886232, NC_000017.10:g.33428366G>A, p.R141X) was observed in two unrelated individuals aged under 40. One of these patients had a family history of late-onset stomach cancer in second-degree relatives. The pathogenic mutation in the PTEN gene (rs786201044, NC_000010.10:g.89692922T>C, p.C136R) was observed in a 38 years old breast cancer patient with no family history. In our study, we first describe pathogenic mutations in RAD51D and PTEN genes found in young Buryat patients.

New germline BRCA2 gene variant in the Tuvinian Mongol breast cancer patients

To date, there are a limited number of reports on inherited gene mutations associated with breast cancer (BC) among Mongoloid indigenous people in Russia. The present study aimed at identifying the BC-associated genes in 26 Russian Mongoloid BC patients (Buryats, Tuvinians and others). The median age of the patients at the time of breast cancer diagnosis was 41 years (range 25-51 years). Genomic DNA isolated from blood samples was used to prepare libraries using a capture-based target enrichment kit (Hereditary Cancer Solution™, SOPHiA GENETICS, Switzerland) covering 27 genes (ATM, APC, BARD1, BRCA1, BRCA2, BRIP1, CDH1, CHEK2, EPCAM, FAM175A, MLH1, MRE11A, MSH2, MSH6, MUTYH, NBN, PALB2, PIK3CA, PMS2, PMS2CL, PTEN, RAD50, RAD51C, RAD51D, STK11, TP53 and XRCC2). Next-generation sequencing (NGS) was performed on an Illumina NextSeq 500 System (Illumina, USA). In our study, we found 1 Indel and 11 SNPs that passed filters during variant calling. We identified a highly pathogenic germline rs483353122 (c.8208_8209insAG, p.Leu2737Serfs*2) in the BRCA2 gene in six unrelated Tuvinian Mongol BC patients. We also identified a likely damaging germline rs35352891 in the MUTYH gene (c.1118C>T, p.Ala373Val) in one Buryat Mongol BC patient. Other SNPs were classified as variants of uncertain significance. To the best of our knowledge, this report is the first to describe the highly pathogenic variant in the BRCA2 gene (rs483353122) and the likely damaging germline variant in the MUTYH gene (rs35352891) in Russian Mongoloid BC patients with young-onset and/or bilateral and/or familial BC. Further studies are therefore necessary to evaluate the contributions of novel sequence variants to hereditary BC.

EGFR analysis of 21,039 patients with NSCLC: Age-related gradual increase of the L858R mutation frequency in adenocarcinomas and high occurrence of ex19del/L858R mutations in squamous cell carcinomas from females and/or nonsmokers

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Background: EGFR testing in Russia is carried out upon the patronage of Russian Society of Clinical Oncology (RUSSCO), and the results are accumulated in a centralized database. Squamous cell carcinomas (SCC) constitute 60-70% of NSCLC incidence in Russia, however physicians are often discouraged to send NSCLC-SCC for EGFR testing due to low frequency of mutations. Methods: We considered all NSCLC patients analyzed by means of PCR for the presence of EGFR mutations (ex19del and L858R) within years 2012-2017. Results: 21,039 NSCLC patients were tested. EGFR analysis was successful in 20,768 patients (98.7%). EGFR mutations were detected in 3566/17717 (20.1%) adenocarcinomas (AdCa) of the lung (ex19del: 2203 (12.4%); L858R: 1363 (7.7%)). There was an evident age-related increase in the frequency of L858R substitution in AdCa patients (p =0.000, Table). This set of patients included 1,139 NSCLC-SCC cases, and the EGFR mutation was observed in 41 (3.6%) subjects. Among 189 females with NSCLC-SCC, ex19del or L858R were detected in 25 (13.2%) cases. Stratification by smoking status revealed EGFR mutation in 19/242 (7.9%) non-smokers. Conclusions: Elderly NSCLC patients have particularly increased probability to be diagnosed with L858R mutation. In the real-world setting, patients with NSCLC-SCC may have high frequency of EGFR mutations, either due to imprecise histological subtyping or due to yet unknown reasons. All female and non-smoking patients with NSCLC have to undergo EGFR testing irrespectively of tumor histology. [Table: see text]

New variants in the BRCA1 gene in Buryat Mongol breast cancer patients: Report from two families

BACKGROUND

The BRCA1 mutations that are endemic to the Slavic population of Russia have not been identified among indigenous peoples, including the Buryats, Tuvinians and Altaians with hereditary breast cancer.

OBJECTIVE

This study was aimed to identify the mutations that are responsible for the occurrence of hereditary breast cancer in the indigenous population of the Republic of Buryatia.

METHODS

Mutations in the BRCA1 gene were identified in blood samples by Sanger-based sequencing.

RESULTS

We identified 11 polymorphisms (10 SNPs and 1 Indel) and 6 new unclassified sequence variants in the BRCA1 gene. In our study three new sequence variants (c.321T>A, c.366T>A, c.4357+2T>A) were found in position of previously described polymorphisms in dbSNPs: rs80357544 (c.321delT), rs190900046 (c.366T>G), and rs80358152 (c.4357+2T>C), respectively. Other three new sequence variants (c.3605A>G, c.1998A>C, and c.80+13A>C) have not been previously described in dbSNP, BIC and Human Gene Mutation Databases.

CONCLUSIONS

We described six new sequence variants that have never been published in the literature or databases. Further studies are required to confirm the impact of new sequence variants on the risk of breast cancer in the Buryat Mongol population.

Frequency of EGFR mutations in non-small cell lung cancer patients: screening data from West Siberia

BACKGROUND

Incorporation of molecular analysis of the epidermal growth factor receptor (EGFR) gene into routine clinical practice has shown great promise to provide personalized therapy of the non-small cell lung cancer (NSCLC) in the developed world. However, the genetic testing of EGFR mutations has not yet become routine clinical practice in territories remote from the central regions of Russia. Therefore, we aimed to study the frequency of major types of activating mutations of the EGFR gene in NSCLC patients residing in West Siberia.

MATERIALS AND METHODS

We examined EGFR mutations in exons 19 and 21 in 147 NSCLC patients (excluding squamous cell lung carcinomas) by real time polymerase chain reaction.

RESULTS

EGFR mutations were detected in 28 of the 147 (19%) patients. There were 19 (13%) cases with mutations in exon 19 and 9 cases (6%) in exon 21. Mutations were more frequently observed in women (42%, p=0.000) than in men (1%). A significantly higher incidence of EGFR mutations was observed in bronchioloalveolar carcinomas (28%, p=0.019) and in adenocarcinomas (21%, p=0.024) than in large cell carcinomas, mixed adenocarcinomas, and NOS (4%). The EGFR mutation rate was much higher in never-smokers than in smokers: 38% vs. 3% (p=0.000). The frequency of EGFR mutations in the Kemerovo and Tomsk regions was 19%.

CONCLUSIONS

The incorporation of molecular analysis of the EGFR gene into routine clinical practice will allow clinicians to provide personalised therapy, resulting in a significant increase in survival rates and improvement in life quality of advanced NSCLC patients.

Effect of tocopherol-monoglucoside (TMG), a water-soluble glycosylated derivate of vitamin E, on hematopoietic recovery in irradiated mice

A preparation of alpha-tocopherol monoglucoside (TMG) administered i.p. at a dose of 600 mg/kg immediately after whole body gamma irradiation was examined for its radioprotective efficacy towards bone marrow and peripheral blood nucleated cells. When mice received X-rays at a dose of 5,6 Gy, a marked decrease in bone marrow karyocytes and a reduction of peripheral leukocytes within the early post-irradiated period were observed. However these changes were attenuated in TMG-treated mice. Significant protection of blood lymphocytes was found for the TMG group of mice. The return to normal value of the reduced blood leukocyte count starting from the 8th day was more rapid in TMG-treated mice than in untreated irradiated mice. TMG administration was found to enhance hematopoietic recovery, as measured by the exceeded nucleated bone marrow cell count due to elevated amount of both lymphoid and granulocytic elements in the TMG-group, in comparison with that of both control irradiated and non-irradiated animals. These findings indicate that the radioprotective effect of TMG is apparently realized through its influence on hematopoietic system.