Targeting TP53 Mutations in Myelodysplastic Syndromes

Clinical outcomes and characteristics of patients with TP53-mutated myelodysplastic syndromes

OBJECTIVE

To explore the clinical outcomes and characteristics of TP53-mutated primary myelodysplastic syndromes (MDS).

METHODS

A total of 74 de novo primary MDS patients who were diagnosed and treated in the Department of Hematology of our hospital from January 2018 and September 2021 were analyzed retrospectively. All patients had evaluable blood cell counts, mean corpuscular volume (MCV), lactate dehydrogenase (LDH), bone marrow (BM) morphology, biopsy, and MDS-related 20-gene mutations sequencing. In addition, 69 of 74 patients had complete cytogenetic analysis through conventional chromosome analysis and fluorescence in-situ hybridization.

RESULTS

Patients were divided into two cohorts, the TP53-mutated type (TP53^Mut) group (n = 19) and TP53 wild type (TP53^WT) group (n = 55). Compared with the TP53^WT group, patients in the TP53^Mut group had higher ratios of cytogenetic abnormalities (82.4% vs. 30.8%, P < 0.001), with 5q- karyotype (64.70% vs. 38.5%, P < 0.001), complex karyotype(CK) (64.70% vs. 38.5%, P < 0.001), HR-MDS (94.7% vs. 61.8%, P = 0.008), and acute myelogenous leukemia (AML) transformation (26.3% vs. 12.7%, P < 0.001). Interestingly, patients in the TP53^Mut group had lower median MCV than the TP53^WT group (94.40 fl vs. 101.90 fl, P = 0.008). Furthermore, MCV = 100 fl as cutoff, and found that MCV ≤ 100 fl was more common in the TP53^Mut group (73.7% vs. 38.2%, P < 0.001). After 1-4 courses of HMA ± chemotherapy, the overall response rate of the TP53^Mut group was higher than the TP53^WT group (83.3% vs. 71.4%, P = 0.012). With the median follow-up 12.0 months (1-46 months), the results show that the median OS and leukemia-free survival (LFS) of TP53^Mut group was significantly shorter than the TP53^WT group (P = 0.0018; P = 0.0310). Results of multivariate Cox proportional hazard analyses show TP53 mutation was an independent prognostic factor for the OS (HR 2.724, 95%CI 1.099-6.750, P = 0.030).

CONCLUSION

TP53-mutated primary MDS patients were associated with higher frequency of cytogenetic abnormalities, with 5q- karyotype, CK, AML transformation, higher risk IPSS-R, lower MCV and sensitive to HMA treatment, but worse survival.

Pulmonary infection associated with immune dysfunction is associated with poor prognosis in patients with myelodysplastic syndrome accompanied by TP53 abnormalities

The aim of this study was to examine the characteristics and prognosis of patients with myelodysplastic syndrome (MDS) accompanied by TP53 abnormalities and explore potential prognostic factors and treatment responses. This retrospective analysis included 95 patients with MDS and TP53 abnormalities and 173 patients with MDS without TP53 abnormalities at the Fujian Medical University Union Hospital between January 2016 and June 2023. Among patients with TP53 abnormalities, 26 (27.4%) developed AML during the disease course, with a median transformation time of 5.7 months. Complex karyotypes were observed in 73.1% of patients, and the proportions of -5 or del(5q), -7 or del(7q), +8, and -20 or del(20q) were 81.8%, 54.5%, 30.7%, and 25.0%, respectively. These patients exhibited poor survival, with a median overall survival (OS) of 7.3 months, and had 1- and 2-year OS rates of 42.2% and 21.5%, respectively. The complete response rates for azacitidine monotherapy, venetoclax combined with azacitidine, decitabine monotherapy, and decitabine combined with low-dose chemotherapy were 9.1%, 41.7%, 37.5%, and 33.3%, respectively. Long-term survival was similar among the four treatment groups. Patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) had a median OS of 21.3 months, which trended to be longer than that of patients who did not undergo allo-HSCT (5.6 months; P = 0.1449). Patients with pulmonary infection at diagnosis experienced worse OS than those without pulmonary infection (2.3 months vs. 15.4 months; P < 0.0001). Moreover, 61.9% of patients with pulmonary infection had immune dysfunction, with a ratio of CD4+ to CD8+ T lymphocytes below two. Pulmonary infections and complex karyotypes were independent adverse prognostic factors for OS. In conclusion, TP53 abnormalities in patients with MDS were frequently accompanied by complex karyotypes, and treatments based on hypomethylating agents or venetoclax have limited efficacy. Pulmonary infections associated with immune dysfunction is associated with poor prognosis.

Allogeneic Hematopoietic Cell Transplantation Improves Outcome in Myelodysplastic Syndrome Across High-Risk Genetic Subgroups: Genetic Analysis of the Blood and Marrow Transplant Clinical Trials Network 1102 Study

PURPOSE

Allogeneic hematopoietic cell transplantation (HCT) in patients with myelodysplastic syndrome (MDS) improves overall survival (OS). We evaluated the impact of MDS genetics on the benefit of HCT in a biological assignment (donor v no donor) study.

METHODS

We performed targeted sequencing in 309 patients age 50-75 years with International Prognostic Scoring System (IPSS) intermediate-2 or high-risk MDS, enrolled in the Blood and Marrow Transplant Clinical Trials Network 1102 study and assessed the association of gene mutations with OS. Patients with TP53 mutations were classified as TP53multihit if two alleles were altered (via point mutation, deletion, or copy-neutral loss of heterozygosity).

RESULTS

The distribution of gene mutations was similar in the donor and no donor arms, with TP53 (28% v 29%; P = .89), ASXL1 (23% v 29%; P = .37), and SRSF2 (16% v 16%; P = .99) being most common. OS in patients with a TP53 mutation was worse compared with patients without TP53 mutation (21% ± 5% [SE] v 52% ± 4% at 3 years; P < .001). Among those with a TP53 mutation, OS was similar between TP53single versus TP53multihit (22% ± 8% v 20% ± 6% at 3 years; P = .31). Considering HCT as a time-dependent covariate, patients with a TP53 mutation who underwent HCT had improved OS compared with non-HCT treatment (OS at 3 years: 23% ± 7% v 11% ± 7%; P = .04), associated with a hazard ratio of 3.89; 95% CI, 1.87 to 8.12; P < .001 after adjustment for covariates. OS among patients with molecular IPSS (IPSS-M) very high risk without a TP53 mutation was significantly improved if they had a donor (68% ± 10% v 0% ± 12% at 3 years; P = .001).

CONCLUSION

HCT improved OS compared with non-HCT treatment in patients with TP53 mutations irrespective of TP53 allelic status. Patients with IPSS-M very high risk without a TP53 mutation had favorable outcomes when a donor was available.

Progress toward Better Treatment of Therapy-Related AML

Therapy-related acute myeloid leukemia (t-AML) comprises 10-20% of all newly diagnosed cases of AML and is related to previous use of chemotherapy or ionizing radiotherapy for an unrelated malignant non-myeloid disorder or autoimmune disease. Classic examples include alkylating agents and topoisomerase II inhibitors, whereas newer targeted therapies such as poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitors have emerged as causative agents. Typically, t-AML is characterized by adverse karyotypic abnormalities and molecular lesions that confer a poor prognosis. Nevertheless, there are also cases of t-AML without poor-risk features. The management of these patients remains controversial. We describe the causes and pathophysiology of t-AML, putting emphasis on its mutational heterogeneity, and present recent advances in its treatment including CPX-351, hypomethylating agent plus venetoclax combination, and novel, molecularly targeted agents that promise to improve the cure rates. Evidence supporting personalized medicine for patients with t-AML is presented, as well as the authors' clinical recommendations.

Comparison of the International Consensus and 5th WHO edition classifications of adult myelodysplastic syndromes and acute myeloid leukemia

Several editions of the World Health Organization (WHO) classifications of lympho-hemopoietic neoplasms in 2001, 2008, and 2016 served as the international standard for diagnosis. Since the 4th WHO edition, here referred as WHO-HAEM4, significant clinico-pathological, immunophenotypic, and molecular advances have been made in the field of myeloid neoplasms, which have contributed to refine diagnostic criteria, to upgrade entities previously defined as provisional and to identify new entities. This process has resulted in two recent classification proposals of myeloid neoplasms: the International Consensus Classification (ICC) and the 5th edition of the WHO classification (WHO-HAEM5). In this paper, we review and compare the two classifications in terms of diagnostic criteria and entity definition, with a focus on adult myelodysplastic syndromes/neoplasms (MDS) and acute myeloid leukemia (AML). The goal is to provide a tool to facilitate the work of pathologists, hematologists and researchers involved in the diagnosis and treatment of these hematological malignancies.

TP53-Mutated Myelodysplastic Syndrome and Acute Myeloid Leukemia: Biology, Current Therapy, and Future Directions

TP53-mutated myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) form a distinct group of myeloid disorders with dismal outcomes. TP53-mutated MDS and AML have lower response rates to either induction chemotherapy, hypomethylating agent-based regimens, or venetoclax-based therapies compared with non-TP53-mutated counterparts and a poor median overall survival of 5 to 10 months. Recent advances have identified novel pathogenic mechanisms in TP53-mutated myeloid malignancies, which have the potential to improve treatment strategies in this distinct clinical subgroup. In this review, we discuss recent insights into the biology of TP53-mutated MDS/AML, current treatments, and emerging therapies, including immunotherapeutic and nonimmune-based approaches for this entity.

SIGNIFICANCE

Emerging data on the impact of cytogenetic aberrations, TP53 allelic burden, immunobiology, and tumor microenvironment of TP53-mutated MDS and AML are further unraveling the complexity of this disease. An improved understanding of the functional consequences of TP53 mutations and immune dysregulation in TP53-mutated AML/MDS coupled with dismal outcomes has resulted in a shift from the use of cytotoxic and hypomethylating agent-based therapies to novel immune and nonimmune strategies for the treatment of this entity. It is hoped that these novel, rationally designed combinations will improve outcomes in this area of significant unmet need.

Allogeneic haematopoietic stem cell transplantation with decitabine-containing preconditioning regimen in TP53-mutant myelodysplastic syndromes: A case study

Myelodysplastic syndrome (MDS) with TP53 mutations has a poor prognosis after transplantation, and novel therapeutic means are urgently needed. Decitabine (Dec) monotherapy has demonstrated improved overall response rates in MDS and acute myeloid leukaemia, although these responses were not durable. This study aimed to preliminary evaluate the efficacy of a Dec-containing allogeneic haematopoietic stem cell transplantation (allo-HSCT) preconditioning regimen in TP53-mutant MDS. Nine patients with TP53-mutant myelodysplastic syndromes received the decitabine-containing preconditioning regimen and subsequent myeloablative allo-HCT between April 2013 and September 2021 in different centres. At a median follow-up of 42 months (range, 5 to 61 months), the overall survival (OS) was 89% (8/9), progression-free survival (PFS) was 89% (8/9), and relapse incidence was 11.1%. The incidence of severe acute (grade III-IV) graft-versus-host disease (GVHD) was 22.2% (2/9) and that of chronic moderate-to-severe GVHD was 11.1% (1/9). The 1-year GVHD-free/relapse-free survival (GRFS) was 56% (5/9). In conclusion, we found real-world clinical data that supports the use of a Dec-containing preconditioning regimen before allo-HSCT for possible improved outcomes in TP53-mutant MDS patients; there is therefore an urgent call for an in-depth exploration of the involved mechanism to confirm these preliminary findings.

Cancer spectrum in TP53-deficient golden Syrian hamsters: A new model for Li-Fraumeni syndrome

Background:

The TP53 tumor suppressor gene is the most commonly mutated gene in human cancers. Humans who inherit mutant TP53 alleles develop a wide range of early onset cancers, a disorder called Li-Fraumeni Syndrome (LFS). Trp53-deficient mice recapitulate most but not all of the cancer phenotypes observed in TP53-deficient human cancers, indicating that new animal models may complement current mouse models and better inform on human disease development.

Materials and Methods:

The recent application of CRISPR/Cas9 genetic engineering technology has permitted the emergence of golden Syrian hamsters as genetic models for wide range of diseases, including cancer. Here, the first cancer phenotype of TP53 knockout golden Syrian hamsters is described.

Results:

Hamsters that are homozygous for TP53 mutations become moribund on average ~ 139 days of age, while hamsters that are heterozygous become moribund at ~ 286 days. TP53 homozygous knockout hamsters develop a wide range of cancers, often synchronous and metastatic to multiple tissues, including lymphomas, several sarcomas, especially hemangiosarcomas, myeloid leukemias and several carcinomas. TP53 heterozygous mutants develop a more restricted tumor spectrum, primarily lymphomas.

Conclusions:

Overall, hamsters may provide insights into how TP53 deficiency leads to cancer in humans and can become a new model to test novel therapies.

Restoring two tumor suppressor pathways with one PAWI

In this issue of Cell Chemical Biology, Cheng et al. (2021) identify a class of drugs that activate a mitotic stress-dependent signaling cascade, which culminates in p53 activation and Wnt pathway inhibition (PAWI). PAWI compounds may therefore be effective in cancers associated with loss of p53 and activation of Wnt signaling.

Emerging agents and regimens for AML

Until recently, acute myeloid leukemia (AML) patients used to have limited treatment options, depending solely on cytarabine + anthracycline (7 + 3) intensive chemotherapy and hypomethylating agents. Allogeneic stem cell transplantation (Allo-SCT) played an important role to improve the survival of eligible AML patients in the past several decades. The exploration of the genomic and molecular landscape of AML, identification of mutations associated with the pathogenesis of AML, and the understanding of the mechanisms of resistance to treatment from excellent translational research helped to expand the treatment options of AML quickly in the past few years, resulting in noteworthy breakthroughs and FDA approvals of new therapeutic treatments in AML patients. Targeted therapies and combinations of different classes of therapeutic agents to overcome treatment resistance further expanded the treatment options and improved survival. Immunotherapy, including antibody-based treatment, inhibition of immune negative regulators, and possible CAR T cells might further expand the therapeutic armamentarium for AML. This review is intended to summarize the recent developments in the treatment of AML.

Comprehensive bioinformatics analysis of the TP53 signaling pathway in Wilms' tumor

Background

Differential expression of tumor protein 53 (TP53, or p53) has been observed in multiple cancers. However, the expression levels and prognostic role of TP53 signaling pathway genes in Wilms' tumor (WT) have yet to be fully explored.

Methods

The expression levels of TP53 signaling pathway genes including TP53, mouse double minute 2 (MDM2), mouse double minute 4 (MDM4), cyclin-dependent kinase 2A (CDKN2A), cyclin-dependent kinase 2B (CDKN2B), and tumor suppressor p53-binding protein 1 (TP53BP1) in WT were analyzed using the Oncomine database. Aberration types, co-mutations, mutation locations, signaling pathways, and the prognostic role of TP53 in WT were investigated using cBioPortal. MicroRNA (miRNA) and transcription factor (TF) targets were identified with miRTarBase, miWalk, and ChIP-X Enrichment Analysis 3 (CheA3), respectively. A protein-protein network was constructed using GeneMANIA. The expression of TP53 signaling genes were confirmed in WT samples and normal kidney tissues using the Human Protein Atlas (HPA). Cancer Therapeutics Response Portal (CTRP) was used to analyze the small molecules potentially targeting TP53.

Results

TP53 was significantly expressed in the Cutcliffe Renal (P=0.010), but not in the Yusenko Renal (P=0.094). Meanwhile, MDM2 was significantly overexpressed in the Yusenko Renal (P=0.058), but not in the Cutcliffe Renal (P=0.058). The expression levels of MDM4 no significant difference between the tumor and normal tissue samples. The most common TP53 alteration was missense and the proportion of TP53 pathway-related mutations was 2.3%. Co-expressed genes included ZNF609 (zinc finger protein 609), WRAP53 (WD40-encoding RNA antisense to p53), CNOT2 (CC chemokine receptor 4-negative regulator of transcription 2), and CDH13 (cadherin 13). TP53 alterations indicated poor prognosis of WT (P=1.051e-4). The regulators of the TP53 pathway included miR-485-5p and TFs NR2F2 and KDM5B. The functions of TP53 signaling pathway were signal transduction in response to DNA damage and regulate the cell cycle. The small molecules targeting TP53 included PRIMA-1, RITA, SJ-172550, and SCH-529074.

Conclusions

TP53 was found to be differentially expressed in WT tissues. TP53 mutations indicated poor outcomes of WT. Therefore, pifithrin-mu, PRIMA-1, RITA, SJ-172550, and SCH-529074 could be used in combination with traditional chemotherapy to treat WT.

TP53 in Myelodysplastic Syndromes: Recent Biological and Clinical Findings

TP53 dysregulation plays a pivotal role in the molecular pathogenesis of myelodysplastic syndromes (MDS), identifying a subgroup of patients with peculiar features. In this review we report the recent biological and clinical findings of TP53-mutated MDS, focusing on the molecular pathways activation and on its impact on the cellular physiology. In MDS, TP53 mutational status is deeply associated with del(5q) syndrome and its dysregulation impacts on cell cycle, DNA repair and apoptosis inducing chromosomal instability and the clonal evolution of disease. TP53 defects influence adversely the MDS clinical outcome and the treatment response rate, thus new therapeutic approaches are being developed for these patients. TP53 allelic state characterization and the mutational burden evaluation can therefore predict prognosis and identify the subgroup of patients eligible for targeted therapy. For these reasons, in the era of precision medicine, the MDS diagnostic workup cannot do without the complete assessment of TP53 mutational profile.