Homozygous knockout of p53 in mice leads to early mortality from lymphoma, with almost complete penetrance, thus hampering studies of other tumor histotypes related to p53 alterations. To avoid ...lymphoma development, we crossed p53 knockout mice (BALB-p53 mice) with alymphocytic BALB/c Rag2-/-;Il2rg-/- (RGKO) mice. We compared the tumor spectrum of homozygous (BALB-p53-/-) and heterozygous (BALB-p53+/-) mice with alymphocytic mice (RGKO-p53-/- and RGKO-p53+/-). Lymphoma incidence in BALB-p53-/- mice exceeded 80%, whereas in RGKO-p53-/- it was strongly reduced. The prevalent tumor of RGKO-p53-/- mice was hemangiosarcoma (incidence over 65% in both sexes, mean latency 18 weeks), other tumors included soft tissue sarcomas (incidence ~10%), lung and mammary carcinomas. Tumor spectrum changes occurred also in p53 heterozygotes, in which lymphomas are relatively rare (~20%). RGKO-p53+/- had an increased incidence of hemangiosarcomas, reaching ~30%, and females had an increased incidence of osteosarcomas, reaching ~20%. Osteosarcomas shared with the corresponding human tumors the involvement of limbs and a high metastatic ability, mainly to the lungs. Specific alterations in the expression of p53-related genes (p16Ink4a, p19Arf, p15Ink4b, p21Cip1) were observed. Genetic prevention of lymphoma in p53 knockout mice led to new models of sarcoma development, available for studies on hemangiosarcoma and osteosarcoma onset and metastatization.
Rhabdomyosarcoma is a tumor of striated muscle origin that displays defective myogenic differentiation. Terminal myogenesis
switches off cell proliferation and migration, hence, the promotion of ...rhabdomyosarcoma differentiation should antagonize
tumor growth and metastasis. Terminal myogenesis is controlled by cell-intrinsic myogenic transcription factors like myogenin
and environmental mediators like interleukin 4 (IL-4). We studied whether the expression of myogenin or exposure to IL-4 could
promote the myogenesis of poorly differentiating human rhabdomyosarcoma cells RD/12. Forced expression of myogenin amplified
myosin expression and the formation of myotube-like elements, inhibited cell migration, and reduced the growth of local tumors
and liver metastases in immunodepressed mice. In contrast, exposure to IL-4 promoted cell proliferation and survival, especially
at high cell density, inhibited myogenin expression, and myogenesis. Moreover, IL-4 stimulated the directed migration of cells
with low myogenin levels, but not of cells with higher (spontaneous or forced) levels. Thus, IL-4, which was known to promote
late stages of normal myogenesis, favors growth and migration, and inhibits further differentiation of the myogenic stages
attained by rhabdomyosarcoma cells. Strategies to increase myogenin expression and block IL-4 could simultaneously reduce
growth and migration, and enhance terminal differentiation of rhabdomyosarcoma, thus contributing to the control of tumor
growth and metastatic spread. Mol Cancer Ther 2009;8(4):754–61
The TS/A cell line was established in 1983 from a spontaneous mammary tumor arisen in an inbred BALB/c female mouse. Its features (heterogeneity, low immunogenicity and metastatic ability) rendered ...the TS/A cell line suitable as a preclinical model for studies on tumor-host interactions and for gene therapy approaches. The integrated biological profile of TS/A resulting from the review of the literature could be a path towards the description of a precision experimental model of mammary cancer.
Epidermal growth factor receptor (
EGFR
) gene fusions represent an extremely rare aberration, occurring in approximately 0.05–0.13% non-small cell lung cancer (NSCLC) patients.
RAD51
is the most ...frequently involved partner gene in
EGFR
fusions, but other fusion partner genes have been described. To date, a considerable number of next-generation sequencing (NGS) panels still cannot detect these alterations due to the position of the breakpoint site, mainly involving intron 24 of
EGFR
. Current evidences show that such gene alteration is more likely to occur in lung adenocarcinomas of young, female, non-smoker patients. Also, brain metastases are frequently reported in these patients. Only very few cases in literature described clinical characteristics and outcomes of patients harboring
EGFR
gene fusions, reporting responses to 1st generation
EGFR
tyrosine kinase inhibitors (TKIs). Herein, we report the case of two young non-smoker females with metastatic NSCLC harboring
EGFR
-
RAD51
gene fusion, detected by FoundationOne DX1 assay, who responded to
EGFR
TKIs. The first patient initially received erlotinib, then switched to osimertinib for renal toxicity, while the second was treated with gefitinib. This is, to our knowledge, the first report describing response to the 3rd
EGFR
TKI osimertinib. Our experience highlights the need of a broader molecular profiling in young or never smoker NSCLC patients without detectable molecular aberration using standard NGS panels. Finally, further studies to assess the real prevalence of
EGFR
gene fusions and their spectrum of sensitivity to different
EGFR
TKIs are needed.
Non-small cell lung cancer (NSCLC) patients harboring BRAF non-V600 alterations constitute a heterogeneous and poorly studied population orphan of targeted therapies. We conducted a systematic review ...to detect all BRAF alterations of defined functional class across different cancer types. Then, we searched for NSCLC patients harboring these alterations in the cancer bioportal and in POPLAR and OAK trials using patient-level data, to investigate clinical and genomic differences associated with each BRAF functional class and the prognostic impact of BRAF non-V600 mutations. We found that NSCLC patients harboring distinct classes of BRAF alterations have different clinical characteristics, clinical features and genomic landscape. Moreover, BRAF non-V600 alterations were associated with a poor prognostic impact, apparently regardless of the treatment received. These peculiar features may suggest the use of tailored treatments according to each class of BRAF alteration. Background: In non-small cell lung cancer (NSCLC), BRAF class 1 alterations are effectively targeted by BRAF inhibitors. Conversely, targeted therapies have very low or absent activity in patients carrying class 2 and 3 alterations. The spectrum of BRAF alterations in NSCLC patients, and their accompanying clinical features, genomic landscape and treatment outcomes have been poorly reported. Patients and methods: We identified BRAF alterations of defined functional class across different tumors through a systematic review. Then, we selected NSCLC patients carrying BRAF alterations, according to the systematic review, in the cBioPortal (cBioPortal cohort) to collect and analyze clinical, biomolecular and survival data. Finally, we identified NSCLC patients carrying BRAF non-V600 mutations enrolled in POPLAR and OAK trials (POPLAR/OAK cohort), extracting clinical and survival data for survival analyses. Results: 100 different BRAF non-V600 alterations were identified through the systematic review. In the cBioPortal cohort (n = 139), patients harboring class 2 and 3 alterations were more frequently smokers and had higher tumor mutational burden compared to those carrying class 1 alterations. The spectrum of most frequently co-altered genes was significantly different between BRAF alterations classes, including SETD2, STK11, POM121L12, MUC16, KEAP1, TERT, TP53 and other genes. In the POPLAR/OAK cohort, patients carrying non-V600 BRAF alterations were characterized by poor prognosis compared to BRAF wild-type patients. Conclusions: Different classes of BRAF alterations confer distinctive clinical features, biomolecular signature and disease behavior to NSCLC patients. Non-V600 alterations are characterized by poor prognosis, but key gene co-alterations involved in cancer cell survival and immune pathways may suggest their potential sensitivity to tailored treatments.
Cancer vaccine feasibility would benefit from reducing the number and duration of vaccinations without diminishing efficacy. However, the duration of in vivo studies and the huge number of possible ...variations in vaccination protocols have discouraged their optimization. In this study, we employed an established mouse model of preventive vaccination using HER-2/neu transgenic mice (BALB-neuT) to validate in silico-designed protocols that reduce the number of vaccinations and optimize efficacy. With biological training, the in silico model captured the overall in vivo behavior and highlighted certain critical issues. First, although vaccinations could be reduced in number without sacrificing efficacy, the intensity of early vaccinations was a key determinant of long-term tumor prevention needed for predictive utility in the model. Second, after vaccinations ended, older mice exhibited more rapid tumor onset and sharper decline in antibody levels than young mice, emphasizing immune aging as a key variable in models of vaccine protocols for elderly individuals. Long-term studies confirmed predictions of in silico modeling in which an immune plateau phase, once reached, could be maintained with a reduced number of vaccinations. Furthermore, that rapid priming in young mice is required for long-term antitumor protection, and that the accuracy of mathematical modeling of early immune responses is critical. Finally, that the design and modeling of cancer vaccines and vaccination protocols must take into account the progressive aging of the immune system, by striving to boost immune responses in elderly hosts. Our results show that an integrated in vivo-in silico approach could improve both mathematical and biological models of cancer immunoprevention.
Abstract
Human tumors are dynamic entities that undergo variation, selection and progression within the patient. How well patient-derived xenografts (PDX) recapitulate tumor dynamics? To investigate ...these aspects we established a collection of breast cancer PDX, representative of the main intrinsic subtypes. From 66 primary breast cancer specimens, we obtained 5 transplantable PDXs (8%). The highest rate of PDX stabilization was obtained for HER2-positive (40%) followed by triple negative (17%) and luminal B (14%) subtypes. In 3/66 cases a human lymphoma developed without any further evidence of breast cancer. Two HER-2-positive and one non-amplified, HER-2++, luminal B PDXs were serially transplanted in mice for 7-25 passages over a period of 2-4 years. Morphological and immunohistochemical (ER, PR, Ki67, p53, HER2, HER1, HER3, IGFR) features were highly stable over serial passages of PDXs, which retained the histology and the expression pattern of the tumor of origin. After the second passage, one HER-2++ amplified PDX, named BO-HAT4, was split in six different sublines, which were then studied separately to analyze random and selective events in long-term evolution. Two sublines progressively acquired a marked acceleration of tumor growth rate, whereas the remaining four did not. Metastatic spread was absent in early passages and appeared sporadically in late passages. In vitro cultures derived from early in vivo passages showed a rapid onset of cell senescence, whereas late in vivo passages gave rise to long-term in vitro cultures. However, we have not yet been able to obtain continuous cell lines from breast cancer PDX. To study the onset of resistance to HER-2 targeted therapies, sequential in vivo passages of BO-HAT4 were treated with trastuzumab, leading to a progressive loss of sensitivity. After one year of treatment BO-HAT4 was completely resistant to trastuzumab. We are currently investigating the molecular changes underlying trastuzumab resistance. Interestingly, both trastuzumab-sensitive and -resistant tumors were highly inhibited by neratinib. In conclusion, the low take rate as PDX prevents the generalized analysis of human breast cancer patients. Individual PDX allow the analysis of target therapy response and onset of resistance, however long-term study of transplantable breast cancer PDX show that tumor progression in these model systems is a late and random event. Supported by grants from the Italian Association for Cancer Research (AIRC) and the University of Bologna, Italy.
Citation Format: Lorena Landuzzi, Marianna L. Ianzano, Claudio Ceccarelli, Enrico Di Oto, Giordano Nicoletti, Veronica Giusti, Roberta Laranga, Tania Balboni, Carla De Giovanni, Massimiliano Dall'Ora, Sofia Asioli, Arianna Palladini, Donatella Santini, Maria Pia Foschini, Mario Taffurelli, Pier-Luigi Lollini, Patrizia Nanni. Functional stability, progression and evolution of targeted drug sensitivity of HER-2-positive breast cancer patient-derived xenografts abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 216.
Full-length HER2 oncoprotein and splice variant Delta16 are co-expressed in human breast cancer. We studied their interaction in hybrid transgenic mice bearing human full-length HER2 and Delta16 (F1 ...HER2/Delta16) in comparison to parental HER2 and Delta16 transgenic mice. Mammary carcinomas onset was faster in F1 HER2/Delta16 and Delta16 than in HER2 mice, however tumor growth was slower, and metastatic spread was comparable in all transgenic mice. Full-length HER2 tumors contained few large vessels or vascular
, whereas Delta16 tumors presented a more regular vascularization with numerous endothelium-lined small vessels. Delta16-expressing tumors showed a higher accumulation of
. injected doxorubicin than tumors expressing full-length HER2. F1 HER2/Delta16 tumors with high full-length HER2 expression made few large vessels, whereas tumors with low full-length HER2 and high Delta16 contained numerous small vessels and expressed higher levels of VEGF and VEGFR2. Trastuzumab strongly inhibited tumor onset in F1 HER2/Delta16 and Delta16 mice, but not in full-length HER2 mice. Addiction of F1 tumors to Delta16 was also shown by long-term stability of Delta16 levels during serial transplants, in contrast full-length HER2 levels underwent wide fluctuations. In conclusion, full-length HER2 leads to a faster tumor growth and to an irregular vascularization, whereas Delta16 leads to a faster tumor onset, with more regular vessels, which in turn could better transport cytotoxic drugs within the tumor, and to a higher sensitivity to targeted therapeutic agents. F1 HER2/Delta16 mice are a new immunocompetent mouse model, complementary to patient-derived xenografts, for studies of mammary carcinoma onset, prevention and therapy.
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