Arsenic trioxide extends survival of Li-Fraumeni syndrome mimicking mouse.

Li-Fraumeni syndrome (LFS) is characterized by germline mutations occurring on one allele of genome guardian TP53. It is a severe cancer predisposition syndrome with a poor prognosis, partly due to the frequent development of subsequent primary tumors following DNA-damaging therapies. Here we explored, for the first time, the effectiveness of mutant p53 rescue compound in treating LFS-mimicking mice harboring a deleterious p53 mutation. Among the ten p53 hotspot mutations in IARC LFS cohorts, R282W is one of the mutations predicting the poorest survival prognosis and the earliest tumor onset. Among the six clinical-stage mutant p53 rescue compounds, arsenic trioxide (ATO) effectively restored transactivation activity to p53-R282W. We thus constructed a heterozygous Trp53 R279W (corresponding to human R282W) mouse model for the ATO treatment study. The p53R279W/+ (W/+) mice exhibited tumor onset and overall survival well mimicking the ones of human LFS. Further, 35 mg/L ATO addition in drink water significantly extended the median survival of W/+ mice (from 460 to 596 days, hazard ratio = 0.4003, P = 0.0008). In the isolated tumors from ATO-treated W/+ mice, the representative p53 targets including Cdkn1a, Mdm2, and Tigar were significantly upregulated, accompanying with a decreased level of the proliferation marker Ki67 and increased level of apoptosis marker TUNEL. Together, the non-genotoxic treatment of p53 rescue compound ATO holds promise as an alternative for LFS therapeutic.

Lung adenocarcinoma in a patient with Li-Fraumeni syndrome bearing a novel germ-line mutation, TP53R333Vfs*12.

Germline mutations of TP53 are responsible for Li-Fraumeni syndrome in its 60-80%. We found a novel germline mutation, TP53: c.997del:p.R333Vfs*12 (NM_000546.6, GRCh, 17:7670713..7670713). The proband is a 40-year-old female, who was suffered from osteosarcoma in her right forearm at her age of 11. She was also suffered from lung adenocarcinoma in her right upper lobe and bone metastasis in her right scapula at her age of 37. She was treated with gefitinib, an epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) because of EGFR mutation (L747-S752 del). Her bone metastasis became resistant after 1-year treatment. Bone metastasis had an additional EGFR mutation (T790M). The secondary treatment with osimertinib, an another EGFR-TKI, can successfully control the tumors for over 2 years. This TP53 mutation (R333Vfs*12) was first found in lung adenocarcinomas. The therapeutic effect of osimertinib for this triple mutant lung adenocarcinoma is better than the previous report.

Li-Fraumeni Syndrome Disease Model: A Platform to Develop Precision Cancer Therapy Targeting Oncogenic p53.

Li-Fraumeni syndrome (LFS) is a rare hereditary autosomal dominant cancer disorder. Germline mutations in TP53, the gene encoding p53, are responsible for most cases of LFS. TP53 is also the most commonly mutated gene in human cancers. Because inhibition of mutant p53 is considered to be a promising therapeutic strategy to treat these diseases, LFS provides a perfect genetic model to study p53 mutation-associated malignancies as well as to screen potential compounds targeting oncogenic p53. In this review we briefly summarize the biology of LFS and current understanding of the oncogenic functions of mutant p53 in cancer development. We discuss the strengths and limitations of current LFS disease models, and touch on existing compounds targeting oncogenic p53 and in vitro clinical trials to develop new ones. Finally, we discuss how recently developed methodologies can be integrated into the LFS induced pluripotent stem cell (iPSC) platform to develop precision cancer therapy.

Destabilization of Mutant p53 Proteins Suppresses Tumor Growth.

Sustained mutant p53 is required for tumor maintenance and is a therapeutic target in vivo.

Successful treatment of a patient with Li-Fraumeni syndrome and metastatic lung adenocarcinoma harboring synchronous EGFR L858R and ERBB2 extracellular domain S310F mutations with the pan-HER inhibitor afatinib.

We report the case of a young, never-smoker woman with Li-Fraumeni syndrome and advanced lung adenocarcinoma refractory to multiple lines of conventional chemotherapy and negative for actionable alterations by routine testing. Comprehensive genomic profiling by clinical-grade next generation sequencing was performed on 3320 exons of 184 cancer-related genes and 37 introns of 14 genes frequently rearranged in cancer. The tumor was found to harbor both EGFR L858R and ERBB2 S310F alterations and also tested positive for a known TP53 germline mutation. The presence of the EGFR mutation was further validated by direct sequencing. Based on these results, a dual EGFR/ERBB2 inhibitor, afatinib, was chosen for treatment. The patient achieved a rapid, complete, and durable response to afatinib monotherapy, both clinically and radiographically. The treatment was very well tolerated. This unique case raises practical questions as to the challenges of molecular testing and highlights the potential association of p53 mutations with concurrent EGFR and ERBB2 aberrations. As this case powerfully illustrates, the combination of broad genomic profiling and targeted therapy guided by mutational analysis offers the possibility of precision management of refractory advanced adenocarcinoma in the background of neoplastic syndromes.

Targeted therapy for hereditary cancer syndromes: hereditary breast and ovarian cancer syndrome, Lynch syndrome, familial adenomatous polyposis, and Li-Fraumeni syndrome.

Cancer genetics has rapidly evolved in the last two decades. Understanding and exploring the several genetic pathways in the cancer cell is the foundation of targeted therapy. Several genomic aberrations have been identified and their role in carcinogenesis is being explored. In contrast to most cancers where these mutations are acquired, patients with hereditary cancer syndromes have inherited genomic aberrations. The understanding of the molecular pathobiology in hereditary cancer syndromes has advanced dramatically. In addition, many molecularly targeted therapies have been developed that could have potential roles in the treatment of patients with hereditary cancer syndromes. In this review, we outline the presentation, molecular biology, and possible targeted therapies for two of the most widely recognized hereditary cancer syndromes -- hereditary breast and ovarian cancer syndrome and hereditary non-polyposis colorectal cancer syndrome (Lynch syndrome). We will also discuss other syndromes such as familial adenomatous polyposis and Li-Fraumeni syndrome (TP53).

Clinical response to a lapatinib-based therapy for a Li-Fraumeni syndrome patient with a novel HER2V659E mutation.

UNLABELLED: Genomic characterization of recurrent breast and lung tumors developed over the course of 10 years in a 29-year-old patient with a germline TP53 mutation (Li-Fraumeni Syndrome) identified oncogenic alterations in the HER2 and EGFR genes across all tumors, including HER2 amplifications, an EGFR-exon 20 insertion, and the first-in-humans HER2V659E mutation showing a phenotypic convergent evolution toward HER2 and EGFR alterations. Following the identification of HER2-activating events in the most recent lung carcinoma and in circulating tumor cells, we treated the reminiscent metastatic lesions with a lapatinib-based therapy. A symptomatic and radiologic clinical response was achieved. HER2V659E sensitivity to lapatinib was confirmed in the laboratory. SIGNIFICANCE: The precise knowledge of the genomic alterations present in tumors is critical to selecting the optimal treatment for each patient. Here, we report the molecular characterization and clinical response to a lapatinib-based therapy for the tumors of a Li-Fraumeni patient showing prevalence of HER2 and EGFR genomic alterations.

Rapamycin extends lifespan and delays tumorigenesis in heterozygous p53+/- mice.

TOR (Target of Rapamycin) pathway accelerates cellular and organismal aging. Similar to rapamycin, p53 can inhibit the mTOR pathway in some mammalian cells. Mice lacking one copy of p53 (p53+/- mice) have an increased cancer incidence and a shorter lifespan. We hypothesize that rapamycin can delay cancer in heterozygous p53+/- mice. Here we show that rapamycin (given in a drinking water) extended the mean lifespan of p53+/- mice by 10% and when treatment started early in life (at the age less than 5 months) by 28%. In addition, rapamycin decreased the incidence of spontaneous tumors. This observation may have applications in management of Li-Fraumeni syndrome patients characterized by heterozygous mutations in the p53 gene.

Enhancement of transcriptional activity of mutant p53 tumor suppressor protein through stabilization of tetramer formation by calix[6]arene derivatives.

Li-Fraumeni syndrome, a hereditary disorder characterized by familial clusters of early-onset multiple tumors, is caused by mutation of the TP53 gene, which encodes the p53 tumor suppressor protein. Mutation of Arg337 to histidine in the tetramerization domain of p53 is most frequently observed in Li-Fraumeni syndrome. This mutation is reported to destabilize the tetrameric structure of p53. We designed and synthesized calix[6]arene derivatives, which have six imidazole or pyrazole groups at the upper rim. In this study, we report, for the first time, the enhancement of the in vivo transcriptional activity of the most common Li-Fraumeni p53 mutant by imidazole-calix[6]arene through stabilization of the oligomer formation.

Li-Fraumeni syndrome: the genetics and treatment considerations for the sarcoma and associated neoplasms.

Li-Fraumeni syndrome is an autosomal dominant disorder first reported by Drs Li and Fraumeni in 1969. Malkin was the first to describe a germline mutation as an underlying defect of Li-Fraumeni syndrome. Cancer risk in mutation carriers has been estimated to be 50% by age 40 and 90% by age 60. Children of affected parents have an approximate 50% risk of inheriting the familial mutation. Functional assays have been established that allow for easy genetic testing for TP53 mutation. Treatment goals center on early detection and surgical resection of affected organ. Targeted therapy for the TP53 gene may hold promise for the future.

Successful treatment of an unresectable choroid plexus carcinoma in a patient with Li-Fraumeni syndrome.

Choroid plexus carcinoma (CPC) is an uncommon central nervous system tumor requiring complete surgical excision for favorable outcome. The authors report the successful treatment of a 2-year-old patient with widely disseminated CPC and Li-Fraumeni syndrome. Following a partial resection of the tumor the patient received chemotherapy consisting of cyclophosphamide, etoposide, and carboplatin. There were no additional surgical procedures and radiation was not administered. Remarkably, the patient remains without evidence of active disease more than 3 years from the completion of therapy. Additional studies are necessary to determine whether this treatment plan can be beneficial to other patients with CPC and whether the patient's p53 mutation had an effect on outcome.

Leukemic and non-leukemic lymphocytes from patients with Li Fraumeni syndrome demonstrate loss of p53 function, Bcl-2 family dysregulation and intrinsic resistance to conventional chemotherapeutic drugs but not flavopiridol.

Li Fraumeni syndrome (LFS) is characterised by a predisposition to the early onset of certain tumors and is associated with germline mutation of the anti-oncogene p53. In this study we analysed the in vitro responses of lymphocytes from two LFS patients to chemotherapeutic drugs in terms of apoptosis induction and the expression of key intracellular proteins that regulate this process. One of the LFS patients also suffered from B-cell chronic lymphocytic leukemia (B-CLL) and hence presented with a light-chain restricted B-cell lymphocytosis while the other patient had entirely normal blood counts. The B-lymphocytes from both LFS patients showed a marked degree of resistance to chlorambucil and fludarabine when compared to age-matched controls but were remarkably sensitive to the novel flavone, flavopiridol. Loss of function of p53 was demonstrated by a failure to induce Bax and p21 protein expression. In addition, altered basal expression patterns of Bcl-2 and Bax, two key regulators of apoptosis, were found in the LFS lymphocytes when compared with controls. These results suggest that LFS lymphocytes carrying a p53 mutation show intrinsic resistance to conventional chemotherapeutic drugs and this is associated with dysregulation of Bcl-2 family proteins. Furthermore, The innate resistance profile was similar in leukemic and non-leukemic lymphocytes and was therefore independent of genetic changes acquired during malignant transformation. Novel agents that induce p53-independent cell killing may be useful not only in the treatment of LFS-associated tumors but also drug resistant tumors in general where p53 and/or Bcl-2 family dysregulation is a feature.