bims-p53act 2026-01-11 papers

bims-p53act

Biomed News

on p53 mutations and anti-cancer therapy response

Issue of 2026–01–11
twelve papers selected by
Toni Martínez Bernabé, Universitat de les Illes Balears

Elucidating cooperative genetic events in DCIS progression in mutant p53-driven breast cancer.
Acquired on-target alterations drive clinical resistance to p53-Y220C reactivators.
Clinical Features and Treatment Strategies of Li-Fraumeni Syndrome Patients With Inherited TP53 Mutations.
Clinical impact of TP53 classifications in previously treated advanced driver-negative non-small cell lung cancer: A biomarker analysis of the OAK and POPLAR randomized clinical trials.
Targeting ceramide metabolism to restore hypoxia-induced apoptosis in p53-deficient colon cancer cells.
SB431542, a Selective Inhibitor of the TGF-β Type I Receptor, Enhances Doxorubicin Antitumor Activity via p63 Activation in Mutant p53 Breast Cancer Cells.
Inhibition of GPX4 induces the death of p53-mutant triple-negative breast cancer cells.
The value of DNA repair gene and TP53 co-mutation in predicting the response of non-small cell lung cancer to immunotherapy.
APOBEC3C coordinates DDX5 in R-loop resolution and dynamic control of Chk1-mediated stress-responsive circuitry as a prerequisite for gemcitabine resistance in p53-deficient cells.
The p53 R181C mutation accumulates through impaired deacetylation by Sirt1 and facilitates tumor development.
p53 status determines the epigenetic response to demethylating agents azacitidine and decitabine.
DNA Damage Sensing and TP53 Function as Modulators of Sensitivity to Calicheamicin-Based Antibody-Drug Conjugates for Acute Leukemia.

Proc Natl Acad Sci U S A. 2026 Jan 13. 123(2): e2526544123

Elucidating cooperative genetic events in DCIS progression in mutant p53-driven breast cancer.

Rhiannon L Morrissey, Joy M McDaniel, Gilda P Chau, Xiaoping Su, Mitheera V, Vidhi Chandra, Beverly R E A Dixon, Adel K El-Naggar, Alastair M Thompson, Guillermina Lozano.

  Ductal carcinoma in situ (DCIS) is a precursor mammary lesion characterized by abnormal epithelial cells in mammary ducts that remain confined to the luminal space. Not all DCIS becomes invasive, and no strategy currently exists in patients to stratify indolent DCIS from DCIS at risk of progression. Several studies of human DCIS and breast cancer suggest that TP53 mutations occur early in DCIS. However, TP53 mutation alone is insufficient for DCIS formation or transformation to invasive disease. Using an autochthonous somatic mouse model of Trp53R245W induced breast cancer (equivalent to the TP53R248W hotspot mutation in humans), we identified DCIS lesions. Through exome sequencing and low-pass whole-genome sequencing, we identified additional genomic changes shared between DCIS and invasive tumors. This comparison nominated seven murine candidate genes, with eight human orthologs. We assessed the cooperativity of these genes with mutant TP53 in human breast cells using acinar morphogenesis and migration assays. Overexpression of TMEM267, which encodes a transmembrane protein overexpressed in 22% of TP53 missense mutant breast cancer cases, in cells with mutant TP53 caused a significant increase in the filled duct, DCIS-like phenotype. We nominate TMEM267 as a cooperating event with mutant TP53 in DCIS progression.

Keywords:  DCIS; breast cancer; mouse models; mutant p53

DOI:  https://doi.org/10.1073/pnas.2526544123
Cancer Discov. 2026 Jan 08.

Acquired on-target alterations drive clinical resistance to p53-Y220C reactivators.

Ferran Fece de la Cruz, Andreas Varkaris, Parasvi S Patel, Elijah W Kushner, Alvin A Morales-Giron, Sangmi Sandra Lee, Ankit Singh, Clara T Kim, Bryanna L Norden, Sara Ehnstrom, Jakob M Riedl, Jacquelyn M Curtis, Haley Barnes, Allison M Kehlmann, Nicholas J Chevalier, Hitomi S Okuma, Manisha Patel, Lori J Wirth, Brendan Connell, Francis Nugent, Leontios Pappas, Kayao Lau, Dejan Juric, Jessica L Hopkins, Keelan Z Guiley, Kevan M Shokat, Doga C Gulhan, Aparna R Parikh, Ryan B Corcoran.

The tumor suppressor TP53 is the most frequently altered gene in cancer, and the Y220C hotspot, found in 1.8% of TP53-mutant tumors, creates a druggable cavity that destabilizes p53. Rezatapopt, a first-in-class, orally bioavailable reactivator of Y220C-mutant p53, has demonstrated promising initial efficacy in the phase 1/2 PYNNACLE trial. We report the first clinical mechanisms of resistance to this therapeutic class. Profiling of circulating tumor DNA, tumor biopsies, and rapid autopsy specimens upon rezatapopt progression revealed multiple heterogenous secondary TP53 alterations in cis with Y220C, including: (1) DNA-binding domain mutations or frameshift/nonsense mutations that abolish transcriptional activity, and (2) mutations within the Y220C binding surface predicted to hinder drug binding. Functional modeling confirmed these double mutants eliminate p53 reactivation and target gene induction by rezatapopt. These findings establish a molecular framework for resistance to p53 Y220C reactivators and inform strategies to overcome resistance with next-generation agents.

DOI: https://doi.org/10.1158/2159-8290.CD-25-1761
Mol Genet Genomic Med. 2026 Jan;14(1): e70177

Clinical Features and Treatment Strategies of Li-Fraumeni Syndrome Patients With Inherited TP53 Mutations.

Keyu Chen, Yufen Xu, Binbin Song, Yuyang Gu, Xiaofang Xu, Jun Cao, Meiyu Fang.

   BACKGROUND: Li-Fraumeni syndrome is a rare autosomal dominant disorder caused by a pathogenic mutation of the tumor suppressor gene TP53. This disease starts at an early age and has been shown to be associated with multiple tumors. The study aims to discuss the clinical and genetic characteristics of Li-Fraumeni syndrome (LFS) and to provide therapeutic experience of LFS.
MATERIALS AND METHODS: We conducted a retrospective analysis of the clinicopathologic features, family history, treatment and follow-up in five LFS patients with germline TP53 (NCBI Gene: 7157, HGNC: 11998, OMIM: 191170) pathogenic/likely pathogenic (P/LP) variants. This research had been approved by the ethics committee and implemented.
RESULTS: Our study involved five LFS patients with germline TP53 P/LP variants, including thyroid cancer, ovarian melanoma, colon cancer, fibrosarcoma, and lung cancer. Among this group of patients, the age at which tumors first appeared was between 24 and 53 years old. Three patients had a family history of tumors, and the other two were probands in the family. Traditional chemotherapy has limited effectiveness in clinical practice and may increase the risk of tumor development. However, immune checkpoint inhibitors (ICIs) have shown unexpected efficacy in patients with high programmed cell death ligand-1 (PD-L1) expression. Next-generation sequencing (NGS) and PD-L1 detection may provide more potential targets for LFS patients to achieve better therapeutic outcomes. In addition, we have added a new TP53 frameshift mutation spectrum, namely c.642_643delTA (p.H214Qfs*7), which belongs to the pathogenic variant. This mutant has not been described in the existing literature.
CONCLUSION: Patients with LFS may be potential beneficiaries of immune checkpoint inhibitors and targeted therapies.

Keywords:  Li‐Fraumeni syndrome; TP53 pathogenic/likely pathogenic variants; germline mutations; hereditary disease; immune checkpoint inhibitors

DOI:  https://doi.org/10.1002/mgg3.70177
Lung Cancer. 2025 Dec 29. pii: S0169-5002(25)00783-4. [Epub ahead of print]212 108891

Clinical impact of TP53 classifications in previously treated advanced driver-negative non-small cell lung cancer: A biomarker analysis of the OAK and POPLAR randomized clinical trials.

Deborah Di-Xin Zhou, Sarah J Lord, Frank Po-Yen Lin, Wendy A Cooper, Milita Zaheed, Robert John Simes, Thomas John, Chee Khoon Lee.

   BACKGROUND: In NSCLC, TP53 mutations are heterogeneous with varied effects on protein synthesis, function and clinical outcomes. We hypothesize that a refined classification of TP53 mutations, beyond binary categorization, could improve prognostication. Furthermore, specific mutations could be associated with enhanced benefit from immune checkpoint inhibitors (ICI) versus chemotherapy. To investigate this, we analyzed data from randomized trials (OAK and POPLAR) which compared atezolizumab to chemotherapy in previously treated advanced driver-negative NSCLC.
METHODS: Participants were classified as TP53 mutant or wild-type using baseline plasma, and by coding mutation, and Olivier's and Poeta's classification. We performed multivariable Cox regression analyses to evaluate the prognostic significance of TP53 mutations, and interaction tests to assess their predictive value.
RESULTS: Among 762 participants, 49% harbored a TP53 mutation. TP53 mutations based on binary categorization were associated with poorer but not statistically significant OS compared to wild-type (adjusted-HR 1.15; 95 %CI 0.96-1.38; P = .12). However, nonsense mutations classified by coding mutations (adjusted-HR 1.71; 95% CI 1.22-2.39;P = .002), non-missense mutations classified by Olivier's classification (adjusted-HR 1.33; 95% CI 1.03-1.74; P = .03) and disruptive mutations classified by Poeta's classification (adjusted-HR 1.33; 95% CI 1.37-1.77; P = .03) were associated with statistically significant poorer OS. TP53 status did not predict differential benefit from ICI versus chemotherapy (interaction P = .45).
CONCLUSION: In advanced driver-negative NSCLC following progression on first-line chemotherapy, nonsense, non-missense and disruptive mutations of TP53 were strongly associated with inferior OS. These data support utilizing a nuanced classification of TP53 mutations as a stratification factor in future trials, and laboratory reporting to aid prognostication.

Keywords:  Chemotherapy; Immune checkpoint inhibitors; NSCLC; TP53

DOI:  https://doi.org/10.1016/j.lungcan.2025.108891
PLoS One. 2026 ;21(1): e0340295

Targeting ceramide metabolism to restore hypoxia-induced apoptosis in p53-deficient colon cancer cells.

Karen Mechleb, Nancy Hourani, Maya Fakhry, Osama A Alyamani, Rouba Hage-Sleiman, Hicham Younes, Antoine Abou Fayad, Nadia Soudani, Amer Sakr, Nadine Darwiche, Georges Nemer, Raya Saab, Marguerite Mrad, Ghassan Dbaibo.

Hypoxic stress in solid tumors triggers growth arrest and apoptosis through p53 activation and stabilization. This environment inactivates p53 and drives the expansion of p53-mutant clones, which accentuate tumor aggressiveness. Ceramide, a signaling sphingolipid, was previously identified as a downstream collaborator with p53 in the stress-induced apoptosis and cell cycle arrest. Among sphingolipids, the balance between pro- and anti-apoptotic products, dictated by the expression and activity of appropriate enzymes, helps determine cell fate in response to hypoxia. The current study aimed to understand the role of ceramide in HCT116 human colon cancer cells response to hypoxia in the presence or absence of p53, and to determine whether the modulation of ceramide metabolism could sensitize the resistant p53-deficient cells to hypoxia-induced cell death. We observed that HCT116 p53-deficient cells were resistant to hypoxic cell death. We explored the role of ceramide in this response by screening for different sphingolipid metabolites through liquid-chromatography-mass spectrometry, and by measuring the expression of key enzymes involved in ceramide biosynthesis and breakdown. We also evaluated the changes in the cellular response to hypoxia associated with introduction of sphingolipid metabolites or with modulating the activity of related sphingolipid-metabolizing enzymes. In hypoxic p53-deficient cells, ceramide was synthesized via the de novo pathway through the action of ceramide synthases and dihydroceramide desaturase (DEGS1) driving the evasion of hypoxia-induced apoptosis. Among the accumulating ceramide species in p53 deficient cells, C24-ceramide was the most abundant and possibly contributing to their resistance. Tipping the sphingolipid balance in favor of pro-apoptotic sphingolipids, through the addition of C6 ceramide or sphingosine, or through the combined pharmacologic inhibition of DEGS1 and sphingosine kinase 1, helped circumvent the cellular resistance to hypoxia-induced apoptosis in cells lacking p53. Therefore, modulating sphingolipid metabolism may be a viable approach in the treatment of solid tumors with hypoxic regions.

DOI: https://doi.org/10.1371/journal.pone.0340295
Front Biosci (Landmark Ed). 2025 Dec 18. 30(12): 45389

SB431542, a Selective Inhibitor of the TGF-β Type I Receptor, Enhances Doxorubicin Antitumor Activity via p63 Activation in Mutant p53 Breast Cancer Cells.

Yu-Ling Kou, Yu-Jie Liu, Tzu-Chi Hsu, Kuan-Yo Wu, Sih-Tong Chen, Jing-Yan Chen, Kuan-Yu Lin, Hsiao-Hsuan Wang, Yi-Ting Cheng, Chia-Chi Chen, Bi-He Cai.

   BACKGROUND: TP53 gene mutations are common in breast cancer and are linked to chemoresistance. p63, a p53 family member, can induce apoptosis independently of p53, representing a potential therapeutic target in TP53-mutant tumors. This study evaluated the synergistic effects of SB431542, a TGF-β type I receptor inhibitor, and doxorubicin in TP53-mutant breast cancer cells.
METHODS: Isoform-specific RT-PCR was used to assess TAp63 and ΔNp63 expression following SB431542 treatment in T47D, MDA-MB-231, and MDA-MB-468 cells. Cell viability was assessed using the CCK8 assay. Synergistic interaction was quantified using the Coefficient of Drug Interaction (CDI). Caspase-3/7 activity assays and immunocytochemistry analyses were performed to evaluate apoptotic signaling and p63 expression. Inhibition studies using PETα, a p53-family inhibitor, and a pan-caspase inhibitor were conducted to determine the pathway dependency of the observed effects.
RESULTS: SB431542 selectively increased TAp63 but not ΔNp63 expression in all three TP53-mutant breast cancer cells. GAS6, a TAp63 target, was also upregulated by SB431542. Treatment with SB431542 and doxorubicin used in combination significantly reduced cell viability (CDI 0.54-0.63), increased caspase activity, and enhanced p63 expression. The anticancer effect was significantly reduced by co-treatment with either the p53-family inhibitor or the pan-caspase inhibitor, confirming that the cytotoxic response was mediated through TAp63 and caspase activation.
CONCLUSIONS: SB431542 potentiates doxorubicin-induced apoptosis in TP53-mutant breast cancer cells by upregulating TAp63 and activating caspase-dependent pathways. These findings suggest that targeting the TGF-β/TAp63 signaling axis may offer a novel therapeutic approach to overcome chemoresistance in aggressive, TP53-mutant breast cancers.

Keywords:  SB431542; breast cancer; doxorubicin; drug interactions; mutation; p63; tumor suppressor protein p53

DOI:  https://doi.org/10.31083/FBL45389
Breast Cancer Res Treat. 2026 Jan 06. 215(2): 49

Inhibition of GPX4 induces the death of p53-mutant triple-negative breast cancer cells.

William M Tahaney, Amanda Lanier, Jing Qian, Cassandra L Moyer, Nghi Nguyen, Yanxia Ma, Jamal Hill, Reid T Powell, Clifford C Stephan, Peter J A Davies, Abhijit Mazumdar, Powel H Brown.

   BACKGROUND: Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer characterized by high rates of tumor protein 53 (TP53) mutation and with limited targeted therapies. Despite being clinically advantageous, direct targeting of mutant TP53 has been challenging. Therefore, we hypothesized that p53-mutant TNBC cells rely upon other potentially targetable survival pathways.
METHODS: In vitro and in silico screens were used to identify drugs that induced preferential death in TP53-mutant cells. The effect of the ferroptosis inducer ML-162 was tested both in vitro and in vivo and the mechanism of cell death following ML-162 treatment or GPX4 knockout was determined.
RESULTS: High-throughput drug screening demonstrated that TP53-mutant TNBCs are highly sensitive to peroxidase, cell cycle, cell division, and proteasome inhibitors. We further characterized the effect of the ferroptosis inducer ML-162 and demonstrated that ML-162 induces preferential ferroptosis in TP53-mutant TNBC cells. Treatment of TP53-mutant xenografts with ML-162 suppressed tumor growth and increased lipid peroxidation in vivo. Testing ferroptosis inducers demonstrated TP53-missense mutant, and not TP53-null or wild-type cells, were more sensitive to ferroptosis, and expression of mutant TP53 genes in p53-null cells sensitized cells to ML-162 treatment.
CONCLUSIONS: This study demonstrates that TP53-mutant TNBC cells have unique survival pathways that can be effectively targeted. Our results illustrate the intrinsic vulnerability of TP53-mutant TNBCs to ferroptosis and highlight GPX4 as a potential target for the precision treatment of TP53-mutant TNBC.

Keywords:   p53 ; Ferroptosis; GPX4; Gain-of-function; TNBC; TP53

DOI:  https://doi.org/10.1007/s10549-025-07865-6
Discov Oncol. 2026 Jan 05. 17(1): 7

The value of DNA repair gene and TP53 co-mutation in predicting the response of non-small cell lung cancer to immunotherapy.

Bin Ye, Chunzhi Wu, Xiaoying Quan, Xiaoli Jia, Lin Yao, Lei Lei, Xiaoyan Chen.

   BACKGROUND: While mutations in DNA repair gene (DDR) or TP53 alone have been linked to favorable outcomes in immunotherapy, their co-mutations may not have the same effect. The co-occurrence of DDR and TP53 mutations may actually impair DNA repair, cause more genomic instability, and worsen prognosis, indicating that they may have a context-specific effect.
METHODS: Clinical characteristics and next-generation sequencing (NGS) data of non-small-cell lung cancer (NSCLC) patients receiving immune checkpoint inhibitors (ICIs) were collected from cBioPortal ( www.cbioportal.org ). The incidence of DDR mutations was calculated. Kaplan-Meier analyses were performed to determine overall survival (OS) for the DDR+/TP53+ group vs. the DDR+/TP53- group using log-rank testing (p = 0.034). Univariate and multivariate Cox analyses were performed to establish prognostic value.
RESULTS: Of the 350 patients studied, 78.6% had DDR mutations, 62% had TP53 mutations. The presence of DDR mutation status demonstrated a significant association with tumor mutational burden (TMB). Patients with DDR+/TP53+ mutations had shorter OS outcomes than DDR+/TP53-. Multivariable analysis confirmed that the presence of co-mutations was an independent predictor of poor outcome and diminished ICI efficacy.
CONCLUSION: While previous reports would suggest that the mutation status of DDR or TP53 leads to a benefit, our results demonstrate that upon co-mutations of DDR/TP53, mutant patients have inferior outcomes in NSCLC for immunotherapy treatments. This signifies that co-mutation status is an important consideration in biomarker-driven treatment strategies.

Keywords:  Co-mutation; DNA repair gene; Immunotherapy; NSCLC; TP53

DOI:  https://doi.org/10.1007/s12672-025-03775-7
Cell Death Dis. 2026 Jan 07. 17(1): 6

APOBEC3C coordinates DDX5 in R-loop resolution and dynamic control of Chk1-mediated stress-responsive circuitry as a prerequisite for gemcitabine resistance in p53-deficient cells.

Li Tao, Yang Zhao, Zhuangzhaung Jiang, Shujing Kong, Yanlin Ding, Tengyang Ni, Weimin Wang, Yanqing Liu.

Genomic instability is a hallmark of cancer, encompassing both sequence and structural alterations that drive tumor evolution and heterogeneity. The APOBEC3 family of deoxycytidine deaminases has emerged as a major source of mutagenic activity in cancers. R-loops are RNA-DNA hybrids and structural barriers that interfere with replication and transcription. Among the APOBEC3 family, APOBEC3C (A3C) is particularly worthy of attention for its upregulation, driving the DNA replication stress tolerance in response to replication stress-inducing drug gemcitabine. However, the molecular mechanisms of gemcitabine resistance and regulatory circuitries mediated by A3C remain largely unknown, especially in checkpoint-deficient tumors. Initially, we screened that A3C was a putative transcriptional target of p53, and p53-deficient H1299 cells harboring A3C elicited a chemoresistant phenotype upon gemcitabine treatment both in vitro and in vivo. A3C expression enhanced Chk1-dependent S-phase checkpoint activation, thus slowing down replication fork progression and facilitating DNA repair. Pull-down assay and proteomic analysis identified that A3C had a specific interaction with the RNA helicase DDX5, which coordinately played critical roles in R-loop resolution. In contrast to A3C, DDX5 expression attenuated Chk1-dependent S-phase checkpoint activation. Knockdown of DDX5 in A3C-proficient H1299 cells attenuated gemcitabine-induced Chk1 activation and enhanced the therapeutic index of gemcitabine by promoting R-loop accumulation. Therefore, we conclude that A3C/DDX5/R-loop complex may impair the sensitivity of gemcitabine by modulating Chk1 dynamics and DNA replication/damage response machinery.

DOI: https://doi.org/10.1038/s41419-025-08215-6
Commun Biol. 2026 Jan 03.

The p53 R181C mutation accumulates through impaired deacetylation by Sirt1 and facilitates tumor development.

Erli Wang, Liangzi Cao, Wendong Guo, Xiang Dong, Wanying Zhang, Xiaowen Zhang, Zhuo Wang, Xia Chen, Aicun Li, Yu Zou, Shikun Li, Kedian Chen, Han Su, Sunrun Cao, Ning Du, Pingyuan Wang, Paul M Hwang, Xiangsheng Liu, Xiaoyu Song, Hongde Xu, Jingwei Liu, Liu Cao.

Li-Fraumeni Syndrome (LFS) is linked to mutations in the p53 gene and is characterized by autosomal dominant early-onset familial cancer susceptibility. The p53R181C mutation is one of the earliest described mutations associated with early-onset familial hereditary breast cancer. Highly stable mutant p53 protein is often a prerequisite for tumor initiation and progression, but the pathways leading to p53R181C accumulation and carcinogenesis are not understood. Here, we found that p53 R181C mutation decreases the interaction of p53 with the Sirt1 deacetylase, resulting in increased p53 K382 acetylation and inhibition of MDM2-mediated ubiquitination and degradation of p53. Moreover, the R181C mutation leads to "loss-of-function" of transcriptional regulating tumor suppressor genes like p21, bax, and PUMA as well as "gain-of-function" of transcriptional regulating tumor promoting genes of PIK3CA, SHC1, SRC and PAK4. This dysregulation promotes genomic instability, enabling cancer cells to evade cell cycle control, senescence and apoptosis, thus facilitating tumor development. Our findings unraveled the mechanism by which the p53R181C mutant protein accumulates and facilitates tumor development.

DOI: https://doi.org/10.1038/s42003-025-09465-y
EMBO Rep. 2026 Jan 07.

p53 status determines the epigenetic response to demethylating agents azacitidine and decitabine.

Emma Langdale Hands, Arndt Wallmann, Gabrielle Oxley, Sophie Storrar, Rochelle D'Souza, Mathew Van de Pette.

  5'-Azacitidine (Aza) and 5-Aza-2'-deoxycytidine (Dac) are widely used demethylating drugs that directly integrate into nucleic acids. They are frequently used interchangeably, surprisingly as their selectivity is unique from the other, with no predictors of response or clinical biomarkers to indicate drug preference. Using these drugs to induce demethylation, we combine DRIPc-Seq, Immunostaining, RNA-Seq and Mass spectrometry to uncover unique cellular responses. Activation of p53, exclusively by Aza, sustains accumulation of R-loops in CpG islands of p53 target genes. This effect is abolished by the removal of p53, compounded by destabilisation of heterochromatin marks. Dac treatment induces global chromatin modification, sustaining DNA damage, which is heightened in the absence of p53. Rescue experiments reverse the changes observed in the epigenome, demonstrating a direct role for p53 in preserving H3K9me3 and H3K27me3. These insights further our knowledge of how cells recognize and respond to methylation changes and uncover novel roles for p53 in modulation of the epigenome. Further to this, we determine a first in kind biomarker in p53 status that may be relevant for clinical settings.

Keywords:  Azacitidine; Decitabine; Epigenetics; R-Loops; p53

DOI:  https://doi.org/10.1038/s44319-025-00678-0
Cancers (Basel). 2025 Dec 25. pii: 67. [Epub ahead of print]18(1):

DNA Damage Sensing and TP53 Function as Modulators of Sensitivity to Calicheamicin-Based Antibody-Drug Conjugates for Acute Leukemia.

Camryn M Pettenger-Willey, George S Laszlo, Margery Gang, Frances M Cole, Colin D Godwin, Sarah Erraiss, Pritha Chanana, Allie R Kehret, Junyang Li, Jacob W Barton, Meghann M Yochim, Eduardo Rodríguez-Arbolí, Roland B Walter.

   BACKGROUND/OBJECTIVES: Approved for treatment of acute leukemia, gemtuzumab ozogamicin (GO) and inotuzumab ozogamicin (InO) are antibody-drug conjugates (ADCs) that deliver a toxic calicheamicin (CLM) derivative. The resistance mechanisms to GO/InO remain incompletely understood.
METHODS: We performed a genome-wide clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 screen for CLM sensitivity genes, and then performed confirmatory cytotoxicity assays.
RESULTS: Several DNA damage pathway regulation genes were identified, most notably TP53. Across 13 acute leukemia cell lines, the six TP53-mutant cell lines (TP53MUT) were indeed 10- to 1000-fold less sensitive to CLM than the seven TP53WT cell lines. In five TP53WT/KO syngeneic cell line pairs we generated, TP53KO cells were significantly less sensitive to CLM than their TP53WT counterparts. In TP53WT but not TP53MUT cells, the MDM2 inhibitor and p53 activator, idasanutlin, enhanced CLM cytotoxicity, demonstrating that decoupling of cells from MDM2-p53 regulation sensitizes leukemia cells to CLM. The ATM inhibitors AZD1390 and lartesertib also significantly enhanced CLM efficacy but did so independent of the TP53 status. In contrast, neither an ATR inhibitor, Chk1/Chk2 inhibitor, Chk2 inhibitor, or a PARP inhibitor significantly impacted CLM-induced cytotoxicity across the thirteen cell lines. Together, our studies identify ATM, MDM2, and TP53-which are in the same cellular response to DNA damage pathway-as key modulators of CLM-induced cytotoxicity in acute leukemia cells.
CONCLUSIONS: These results support further evaluation of combination therapies with corresponding small-molecule inhibitors (currently pursued for therapy of other cancers) toward clinical testing as novel strategies to increase the efficacy of CLM-based ADCs such as GO and InO.

Keywords:  CD22; CD33; CRISPR/Cas9; acute leukemia; calicheamicin; drug screen; gemtuzumab ozogamicin; inotuzumab ozogamicin

DOI:  https://doi.org/10.3390/cancers18010067