CXCR4 Expression as a Prognostic Biomarker in Soft Tissue Sarcomas.

Poor long-term survival in localized high-risk soft tissue sarcomas (STSs) of the extremities and trunk highlights the need to identify new prognostic factors. CXCR4 is a chemokine receptor involved in tumor progression, angiogenesis, and metastasis. The aim of this study was to evaluate the association between CXCR4 expression in tumor tissue and survival in STSs patients treated with neoadjuvant therapy. CXCR4 expression was retrospectively determined by immunohistochemical analysis in serial specimens including initial biopsies, tumors post-neoadjuvant treatment, and tumors after relapse. We found that a positive cytoplasmatic expression of CXCR4 in tumors after neoadjuvant treatment was a predictor of poor recurrence-free survival (RFS) (p = 0.003) and overall survival (p = 0.019) in synovial sarcomas. We also found that positive nuclear CXCR4 expression in the initial biopsies was associated with poor RFS (p = 0.022) in undifferentiated pleomorphic sarcomas. In conclusion, our study adds to the evidence that CXCR4 expression in tumor tissue is a promising prognostic factor for STSs.

Histopathological, Clinical, And Molecular (HICAM) score for patients with colorectal liver metastases.

BACKGROUND: Histopathological and molecular features have been proposed to hold prognostic information, but few have been validated. The aim of this retrospective study was to validate the Genetic And Morphological Evaluation ('GAME') score and assess the impact of histological characteristics on the prognosis in patients with colorectal liver metastases. METHODS: Data were collected from 176 patients with metastatic colorectal cancer undergoing liver resection at Hospital de la Santa Creu i Sant Pau. Patients were classified into Genetic And Morphological Evaluation score groups and relapse-free survival and overall survival were calculated. Histopathological changes in colorectal liver metastases were documented and prognostic variables were selected to create a post-surgery score, called the Histopathological, Clinical, And Molecular ('HICAM') score. RESULTS: Regarding the Genetic And Morphological Evaluation score, the high-risk group had a median relapse-free survival of 8.8 months, compared with 20.5 months for the low-risk group (P = 0.005), and the high-risk group had a median overall survival of 37.8 months, compared with 67.0 months for the low-risk group (P = 0.005). Histological examination of 144 liver samples showed that the desertic immune phenotype was associated with worse overall survival in the multivariable analysis (P = 0.020). The Histopathological, Clinical, And Molecular score variables were age at diagnosis, tumour burden score, carcinoembryonic antigen levels greater than or equal to 20 ng/ml, primary tumour resection, TNM stage at diagnosis, molecular status, histopathological growth patterns, and immune phenotypes of the liver. The high-risk group had a median relapse-free survival of 8.4 months, compared with 20.4 months for the low-risk group (P < 0.001), and a median overall survival of 30.4 months, compared with 105.0 months for the low-risk group (P < 0.001). CONCLUSION: The Genetic And Morphological Evaluation score was validated as a preoperative prognostic tool to predict candidacy for liver resection. The Histopathological, Clinical, And Molecular score could be useful to assess adjuvant treatment after hepatic resection.

Frequency and clinical relevance of DPYD genetic variants in gastrointestinal cancer patients.

OBJECTIVE: To determine the prevalence of loss-of-function variants in the dihydropyrimidine dehydrogenase gene in patients with gastrointestinal neoplasms, assess their clinical relevance, and evaluate the  implementation of a multidisciplinary circuit at three months from its  implementation. METHOD: This is a descriptive, observational and retrospective study, which  included adult patients with gastrointestinal cancer treated at a tertiary  university hospital who underwent dihydropyrimidine dehydrogenase genotyping between September 2019 and December 2020. The  variables collected were sex, age, type of cancer, location, stage, treatment received, indication of treatment and degree of toxicity  developed during the first three cycles. The genotyped variants were  rs3918290 (c.1905+1G>A), rs55886062 (c.1679T>G), rs67376798  (c.2846A>T) and rs75017182 (c.1129-5923C>G). RESULTS: A total of 115 patients were included. The frequency of heterozygous dihydropyrimidine dehydrogenase variant carriers was 9.6% (11  patients). The most frequently identified variant was rs75017182 (6 patients). The second most common variant was rs67376798 (3 patients),  followed by rs3918290 (2 patients). No patients presented with the  rs55886062 variant. Two of the dihydropyrimidine dehydrogenase carriers  developed  grade 3-5 toxicity after the first cycle of a regimen that included  fluoropyrimidines. Both received full doses of fluoropyrimidine, since their  dihydropyrimidine dehydrogenase genotype was unknown before treatment  initiation. None of the dihydropyrimidine dehydrogenase carriers who began treatment with a reduced dose of fluoropyrimidine experienced grade 3-5  toxicity. Since the creation in October 2020 of a multidisciplinary team, with  the active participation of hospital pharmacists, the monthly average of dihydropyrimidine dehydrogenase genotyping studies has increased from 6.4  (January-October) to 17.5 (November-December). CONCLUSIONS: The present study shows a relatively high prevalence of loss-of- function variants in the dihydropyrimidine dehydrogenase gene as well as the  importance of genotyping such variants before starting a treatment with  fluoropyrimidines. Hospital pharmacists can contribute to the implementation  of pharmacogenetics in daily clinical practice in a tertiary hospital.

OBJETIVO: Determinar la prevalencia de variantes de pérdida de función en el  gen de la dihidropirimidina deshidrogenasa (DPYD) en pacientes con tumores  digestivos, valorar su relevancia clínica y evaluar la implementación de un  circuito multidisciplinar tras tres meses de funcionamiento.Método: Estudio descriptivo, observacional y retrospectivo donde se incluyeron los pacientes adultos afectos de tumores digestivos, atendidos en  un hospital universitario de tercer nivel, a los que se había  afectuado el genotipado de DPYD entre septiembre de 2019 y diciembre de  2020. Las variables recogidas fueron sexo, edad, tipo de cáncer, localización,  estadio, tratamiento recibido, indicación del tratamiento y grado de toxicidad desarrollado durante los tres primeros ciclos. Se genotiparon las  variantes rs3918290 (c.1905+1G>A), rs55886062 (c.1679T>G), rs67376798 (c.2846A>T) y rs75017182 (c.1129-5923C>G). RESULTADOS: Se incluyeron 115 pacientes. La frecuencia de portadores en  heterocigosis de variantes del gen DPYD fue del 9,6% (11 pacientes). La  variante más frecuentemente identificada fue el rs75017182 (6 pacientes). La  segunda variante más frecuente fue el rs67376798 (3 pacientes), seguida del  rs3918290 (2 pacientes). Ningún paciente presentó la variante rs55886062.  Dos de los pacientes portadores desarrollaron toxicidad  grados 3-5 tras el  primer ciclo de un esquema que incluía fluoropirimidinas. Ambos recibieron  dosis plenas de fluoropirimidina, puesto que no se conocía el genotipo de DPYD antes de iniciar el tratamiento. Ninguno de los pacientes portadores que  tmpezó el tratamiento con una dosis reducida de fluoropirimidina experimentó  toxicidad grados 3-5. Desde la creación en octubre de 2020 de un equipo  multidisciplinar, con participación activa del farmacéutico hospitalario, se ha  incrementado el número de estudios de genotipado de DPYD de una media de  6,4 estudios mensuales (enero-octubre) a 17,5 (noviembre-diciembre). CONCLUSIONES: Nuestro estudio muestra la relativamente elevada prevalencia de variantes de pérdida de función en el gen DPYD, así como la  importancia de genotiparlas antes de empezar un esquema de tratamiento que  contenga fluoropirimidinas. El farmacéutico hospitalario puede contribuir a la implementación de la farmacogenética en la  práctica clínica diaria en un hospital de tercer nivel.

Frecuencia y relevancia clínica de las variantes del gen DPYD en pacientes con tumores digestivos / Frequency and clinical relevance of DPYD genetic variants in gastrointestinal cancer patients

Objetivo: Determinar la prevalencia de variantes de pérdida de funciónen el gen de la dihidropirimidina deshidrogenasa (DPYD) en pacientescon tumores digestivos, valorar su relevancia clínica y evaluar la implementación de un circuito multidisciplinar tras tres meses de funcionamiento.Método: Estudio descriptivo, observacional y retrospectivo donde seincluyeron los pacientes adultos afectos de tumores digestivos, atendidosen un hospital universitario de tercer nivel, a los que se había efectuado elgenotipado de DPYD entre septiembre de 2019 y diciembre de 2020. Lasvariables recogidas fueron sexo, edad, tipo de cáncer, localización, estadio, tratamiento recibido, indicación del tratamiento y grado de toxicidaddesarrollado durante los tres primeros ciclos. Se genotiparon las variantesrs3918290 (c.1905+1G>A), rs55886062 (c.1679T>G), rs67376798(c.2846A>T) y rs75017182 (c.1129-5923C>G).Resultados: Se incluyeron 115 pacientes. La frecuencia de portadoresen heterocigosis de variantes del gen DPYD fue del 9,6% (11 pacientes).La variante más frecuentemente identificada fue el rs75017182 (6 pacientes). La segunda variante más frecuente fue el rs67376798 (3 pacientes),seguida del rs3918290 (2 pacientes). Ningún paciente presentó la varianters55886062. (AU)

Objective: To determine the prevalence of loss-of-function variants in thedihydropyrimidine dehydrogenase gene in patients with gastrointestinalneoplasms, assess their clinical relevance, and evaluate the implementation of a multidisciplinary circuit at three months from its implementation.Method: This is a descriptive, observational and retrospective study,which included adult patients with gastrointestinal cancer treated at atertiary university hospital who underwent dihydropyrimidine dehydrogenase genotyping between September 2019 and December 2020.The variables collected were sex, age, type of cancer, location, stage,treatment received, indication of treatment and degree of toxicity developed during the first three cycles. The genotyped variants were rs3918290(c.1905+1G>A), rs55886062 (c.1679T>G), rs67376798 (c.2846A>T)and rs75017182 (c.1129-5923C>G).Results: A total of 115 patients were included. The frequency of heterozygous dihydropyrimidine dehydrogenase variant carriers was 9.6%(11 patients). The most frequently identified variant was rs75017182 (6 patients).The second most common variant was rs67376798 (3 patients), followedby rs3918290 (2 patients). No patients presented with the rs55886062variant. (AU)

Novel Somatic Genetic Variants as Predictors of Resistance to EGFR-Targeted Therapies in Metastatic Colorectal Cancer Patients.

BACKGROUND: About 40% of RAS/BRAF wild-type metastatic colorectal cancer (mCRC) patients undergoing anti-EGFR-based therapy have poor outcomes. Treatment failure is not only associated with poorer prognosis but higher healthcare costs. Our aim was to identify novel somatic genetic variants in the primary tumor and assess their effect on anti-EGFR response. PATIENTS AND METHODS: Tumor (somatic) and blood (germline) DNA samples were obtained from two well-defined cohorts of mCRC patients, those sensitive and those resistant to EGFR blockade. Genetic variant screening of 43 EGFR-related genes was performed using targeted next-generation sequencing (NGS). Relevant clinical data were collected through chart review to assess genetic results. RESULTS: Among 61 patients, 38 were sensitive and 23 were resistant to treatment. We identified eight somatic variants that predicted non-response. Three were located in insulin-related genes (I668N and E1218K in IGF1R, T1156M in IRS2) and three in genes belonging to the LRIG family (T152T in LRIG1, S697L in LRIG2 and V812M in LRIG3). The remaining two variants were found in NRAS (G115Efs*46) and PDGFRA (T301T). We did not identify any somatic variants related to good response. CONCLUSIONS: This study provides evidence that novel somatic genetic variants along the EGFR-triggered pathway could modulate the response to anti-EGFR drugs in mCRC patients. It also highlights the influence of insulin-related genes and LRIG genes on anti-EGFR efficacy. Our findings could help characterize patients who are resistant to anti-EGFR blockade despite harboring RAS/BRAF wild-type tumors.

ABCB1 Genetic Variants as Predictors of Irinotecan-Induced Severe Gastrointestinal Toxicity in Metastatic Colorectal Cancer Patients.

Irinotecan is widely used in the treatment of metastatic colorectal cancer (mCRC) despite its severe toxicities. Toxicity is often associated with the UGT1A1*28/*28 genotype. An explanation for idiopathic toxicity beyond the UGT1A1 biomarker, however, remains a major concern for clinicians. One of the main irinotecan transporters is P-glycoprotein (P-gp), which is a hepatic efflux pump encoded by ABCB1. P-gp is involved in the biliary excretion of irinotecan and its active metabolite SN-38. We aimed to assess whether functional variants in ABCB1 also contribute to identifying patients at risk of toxicity. A cohort of 308 mCRC patients treated with irinotecan-based regimens were genotyped for polymorphisms in ABCB1 (rs1128503, rs2032582, and rs1045642). The effect of these variants and their haplotypes on irinotecan-induced severe toxicity (diarrhea, neutropenia, asthenia, nausea, and mucositis) was assessed. After adjusting for the relevant clinical and pathological parameters in the multivariate analysis, we found rs1128503 was significantly associated with severe diarrhea and mucositis (P=0.014 and P=0.002, respectively). Additionally, rs2032582 was associated with severe mucositis (P<0.001). Our results show that rs1128503 genotyping could help to predict severe gastrointestinal toxicity induced by irinotecan.

Clinical value of next generation sequencing of plasma cell-free DNA in gastrointestinal stromal tumors.

BACKGROUND: Gastrointestinal stromal tumor (GIST) initiation and evolution is commonly framed by KIT/PDGFRA oncogenic activation, and in later stages by the polyclonal expansion of resistant subpopulations harboring KIT secondary mutations after the onset of imatinib resistance. Thus, circulating tumor (ct)DNA determination is expected to be an informative non-invasive dynamic biomarker in GIST patients. METHODS: We performed amplicon-based next-generation sequencing (NGS) across 60 clinically relevant genes in 37 plasma samples from 18 GIST patients collected prospectively. ctDNA alterations were compared with NGS of matched tumor tissue samples (obtained either simultaneously or at the time of diagnosis) and cross-validated with droplet digital PCR (ddPCR). RESULTS: We were able to identify cfDNA mutations in five out of 18 patients had detectable in at least one timepoint. Overall, NGS sensitivity for detection of cell-free (cf)DNA mutations in plasma was 28.6%, showing high concordance with ddPCR confirmation. We found that GIST had relatively low ctDNA shedding, and mutations were at low allele frequencies. ctDNA was detected only in GIST patients with advanced disease after imatinib failure, predicting tumor dynamics in serial monitoring. KIT secondary mutations were the only mechanism of resistance found across 10 imatinib-resistant GIST patients progressing to sunitinib or regorafenib. CONCLUSIONS: ctDNA evaluation with amplicon-based NGS detects KIT primary and secondary mutations in metastatic GIST patients, particularly after imatinib progression. GIST exhibits low ctDNA shedding, but ctDNA monitoring, when positive, reflects tumor dynamics.

Pharmacogenetic clinical randomised phase II trial to evaluate the efficacy and safety of FOLFIRI with high-dose irinotecan (HD-FOLFIRI) in metastatic colorectal cancer patients according to their UGT1A 1 genotype.

BACKGROUND: Patients harbouring the UGT1A1*28/*28 genotype are at risk of severe toxicity with the standard irinotecan dose. However, this dose is considerably lower than the dose that can be tolerated by UGT1A1*1/*1 and *1/*28 patients. This randomised phase II trial evaluated the efficacy and safety of the FOLFIRI regimen with high-dose irinotecan (HD-FOLFIRI) in metastatic colorectal cancer patients. METHODS: Eighty-two patients with the UGT1A1*1/*1 or the *1/*28 genotype were randomised to receive HD-FOLFIRI versus FOLFIRI. Patients with the UGT1A1*28/*28 genotype were excluded. In the experimental group, the irinotecan dose was 300 mg/m2 for UGT1A1*1/*1 and 260 mg/m2 for *1/*28 patients. In the control group, the dose was 180 mg/m2. We analysed the overall response rate (ORR), toxicity, and survival. RESULTS: The ORR was significantly higher in the HD-FOLFIRI group (67.5 versus 43.6%; p = 0.001 OR: 1.73 [95% CI:1.03-2.93]). Neutropenia (17.7%), diarrhoea (5.1%), and asthenia (5.1%) were the most common grade 3-4 toxicity. No differences were observed in severe toxicity (22.5% versus 20.5%), dose reduction (22.5% versus 28.2%), or prophylactic G-CSF (17.5% versus 12.8%). No difference in survival was found. CONCLUSIONS: Patients with the UGT1A1*1/*1 and *1/*28 genotypes can receive high doses of irinotecan to achieve a more favourable ORR without significant adverse events.

Relevance of CYP3A4*20, UGT1A1*37 and UGT1A1*28 variants in irinotecan-induced severe toxicity.

Severe irinotecan-induced toxicity is associated with UGT1A1 polymorphisms. However, some patients develop side-effects despite harbouring a normal UGT1A1 genotype. As CYP3A4 is also an irinotecan-metabolizing enzyme, our study aimed to elucidate the influence of the CYP3A4*20 loss-of-function allele in the toxicity profile of these patients. Three-hundred and eight metastatic colorectal cancer patients treated with an irinotecan-containing chemotherapy were studied. The presence of CYP3A4*20, UGT1A1*37 and UGT1A1*28 alleles was tested. Associations between these genetic variants and toxicity were evaluated. UGT1A1*28 was significantly associated with severe diarrhoea, neutropenia and asthenia (P = 0.002, P = 0.037 and P = 0.041, respectively). One patient with the UGT1A1*28/*37 genotype presented with grade IV neutropenia and lethal septic shock. One heterozygous UGT1A1 (*1/*28) patient also carried the CYP3A4*20 allele but did not develop toxicity. We confirm that UGT1A1*37 and UGT1A1*28 are associated with severe toxicity and suggest that the CYP3A4*20 allele does not play a role in irinotecan-induced toxicity.

Genetic variants in the VEGF pathway as prognostic factors in stages II and III colon cancer.

The role of vascular endothelial growth factor (VEGF) gene polymorphisms in the prognosis of colon cancer prognosis remains unclear. We evaluated the influence of 28 single-nucleotide polymorphisms in 12 genes in the VEGF pathway on the prognosis of 347 patients with stage II-III colon cancer. We found that rs9513070 (VEGFR1) and rs1137282 (KRAS) were associated with overall survival in stage II colon cancer patients (p = 0.025 and p = 0.001, respectively). When primary tumor location was considered, rs9513070 was also associated with relapse-free and overall survival (p = 0.033 and p = 0.031, respectively) in left colon cancer patients. Additionally, rs35251833 in the ITGAV gene correlated with relapse-free survival (p = 0.032). This study provides evidence that germline polymorphisms in VEGFR1, KRAS and ITGAV genes are associated with prognosis in stages II-III colon cancer patients. As stage and tumor location are correlated with prognosis, future genetic studies should stratify colon cancer patients according to these parameters.

Detection of human herpesvirus 8 sequences in cutaneous cherry angiomas.

Cherry angiomas (CAs) are common vascular benign skin tumors, characterized by abnormal angiogenesis, whose etiology is still unclear and poorly studied. We investigated the presence of HHV8 in CAs due to virus ability of inducing neoangiogenesis in endothelial cells. A total of 29 patients were enrolled in a randomized, controlled, blinded analysis of skin specimens including various vascular lesions. All clinical samples were anonymized and analyzed by three different biomolecular assays to minimize the risk of false positive/negative results. Results showed that 53 % of eruptive CAs harbor HHV8 sequences, with the highest viral loads in samples derived from immunosuppressed patients. By contrast, no paucilesional CAs were positive for HHV8. Considering HHV8 prevalence in the Mediterranean population (10-15 %), results obtained in eruptive CAs are significant and suggest for the first time a possible involvement of HHV8 in eruptive cherry angiomas development, particularly in the context of immunosuppression, similar to that recognized for major HHV8-induced pathologies.

Retinoids in the chemoprevention of non-melanoma skin cancers: why, when and how.

INTRODUCTION: The chemoprevention refers to the use of various types of chemical agents for preventing carcinogenic progression. Systemic retinoids are the most studied chemopreventive agents due to their capacity to regulate cell proliferation and their demonstrated efficacy in several clinical studies. OBJECTIVES: The aim of the authors was to give precise indications regarding the use of the systemic retinoid in the chemoprevention of non-melanoma skin cancer (NMSC). METHODS: The authors reviewed the literature found through a search to MEDLINE (from 2001 to December 2011). RESULTS: Both acitretin and isotretinoin are effective for the prevention of NMSC. Isotretinoin is preferred in xeroderma pigmentosum and nevoid basal cell carcinoma syndrome, whereas acitretin is more used in transplant recipients, psoriasis and severe sun damage. CONCLUSION: Despite numerous studies of the literature concerning retinoids in chemoprevention of NMSC, precise details of the type of retinoid to use, dosage and the duration of this preventive treatment and how to manage side effects in the case of long-lasting treatment are still not uniform and comparable. Moreover, neither guidelines nor approval by Food and Drug Administration exist to regulate the use of retinoids in chemoprevention.

Total body skin examination for skin cancer screening in patients with focused symptoms.

BACKGROUND: The value of total body skin examination (TBSE) for skin cancer screening is controversial. OBJECTIVE: We sought to determine whether TBSE could be helpful in patients with focused skin symptoms who would not otherwise have undergone TBSE. METHODS: In a prospective, multicenter, cross-sectional study consecutive adult patients were recruited during a period of 18 months. Physicians first inspected problem areas and uncovered areas and then performed TBSE. Equivocal lesions detected in both steps were excised or biopsied. Primary outcomes were the absolute and relative risks of missing skin cancer and the number of patients needed to examine to detect melanoma or another malignancy. A secondary outcome was the proportion of false-positive results obtained by TBSE. RESULTS: We examined 14,381 patients and detected 40 (0.3%) patients with melanoma and 299 (2.1%) with at least one nonmelanoma skin cancer by TBSE. In 195 (1.3%) patients equivocal lesions found by TBSE turned out to be benign. We calculated that 47 patients need to be examined by TBSE to find one skin malignancy and 400 patients to detect one melanoma. The risk of missing one malignancy if not performing TBSE was 2.17% (95% confidence interval 1.25-3.74). Factors significantly increasing the chance to find a skin cancer were age, male gender, previous nonmelanoma skin cancer, fair skin type, skin tumor as the reason for consultation, and presence of an equivocal lesion on problem/uncovered areas. LIMITATIONS: The impact of TBSE on skin cancer mortality was not evaluated. CONCLUSIONS: TBSE improves skin cancer detection in patients with focused skin symptoms and shows a low rate of false-positive results.

Imatinib sensitivity in BCR-ABL1-positive chronic myeloid leukemia cells is regulated by the remaining normal ABL1 allele.

Chronic myeloid leukemia in chronic phase (CML-CP) cells that harbor oncogenic BCR-ABL1 and normal ABL1 allele often become resistant to the ABL1 kinase inhibitor imatinib. Here, we report that loss of the remaining normal ABL1 allele in these tumors, which results from cryptic interstitial deletion in 9q34 in patients who did not achieve a complete cytogenetic remission (CCyR) during treatment, engenders a novel unexpected mechanism of imatinib resistance. BCR-ABL1-positive Abl1(-/-) leukemia cells were refractory to imatinib as indicated by persistent BCR-ABL1-mediated tyrosine phosphorylation, lack of BCR-ABL1 protein degradation, increased cell survival, and clonogenic activity. Expression of ABL1 kinase, but not a kinase-dead mutant, restored the antileukemic effects of imatinib in ABL1-negative chronic myelogenous leukemia (CML) cells and in BCR-ABL1-positive Abl1(-/-) murine leukemia cells. The intracellular concentration of imatinib and expression of its transporters were not affected, although proteins involved in BCR-ABL1 degradation were downregulated in Abl1(-/-) cells. Furthermore, 12 genes associated with imatinib resistance were favorably deregulated in Abl1(-/-) leukemia. Taken together, our results indicate that loss of the normal ABL1 kinase may serve as a key prognostic factor that exerts major impact on CML treatment outcomes.

Genomic amplification of BCR/ABL1 and a region downstream of ABL1 in chronic myeloid leukaemia: a FISH mapping study of CML patients and cell lines.

BACKGROUND: Chronic myeloid leukaemia (CML) is characterized by the expression of the BCR/ABL1 fusion gene, a constitutively activated tyrosine kinase that commonly results from the formation of the Philadelphia (Ph) chromosome after a t(9;22)(q34;q11) or variant rearrangement. The duplication of the Ph chromosome is a recurring abnormality acquired during disease progression, whereas intrachromosomal amplification of BCR/ABL1 is a rare phenomenon and has been associated with imatinib therapy resistance. Archival bone marrow chromosome suspensions from 19 CML patients known to carry more than 1 copy of BCR/ABL1 and 10 CML cell lines were analyzed by fluorescent in situ hybridization with a panel of probes from 9q34.1-qter to investigate whether they carried two identical copies of the Ph chromosome or, instead, one or both Ph contained cryptic imbalances of some regions. RESULTS: A duplication of the entire Ph chromosome with no further events involving the derivative 22 was found in 12 patients. In contrast, a sideline with either 1 or 2 isochromosomes of the Ph chromosome was identified in 6 patients but none of the cell lines. In one of the patients a translocation between the distal end of one arm of the isoderivative chromosome 22 and a third chromosome was revealed. 2 patients were found to carry marker structures harbouring high copy number gains of BCR/ABL1 fusion along with a variable part of 9q34 region downstream of ABL1 breakpoint, similarly to the markers present in the imatinib resistant cell line K562. We identified the following regions of amplification: 9q34.1 → q34.2 and 9q34.1 → qter, with a common minimum amplified region of 682 Kb. One of the patients had 5 BCR/ABL1 positive clones with variable level of 9q34 amplifications on a variety of structures, from an isoderivative 22 to tandem duplications. CONCLUSIONS: These data confirm that the intrachromosomal genomic amplification of BCR/ABL1 that occurs in some CML patients during disease progression also involves amplification of 9q34 gene-rich sequences downstream of ABL1 breakpoint. The variety of rearrangements identified in this relatively small cohort demonstrates that the Ph chromosome is not a stable structure but prone to further rearrangements during disease progression.