A personalized approach to lymphoproliferations in patients with inborn errors of immunity.

Biopsies from patients with inborn error of immunity (IEI) may pose a diagnostic challenge due to the abnormal anatomy of their lymphoid organs and the tendency for the development of lymphoproliferations in various organs, some of which may lead to the wrong impression of malignant lymphoma which may prompt aggressive unnecessary treatment. In this article we will review typical histologic findings in various IEI's described in the literature and discuss the appropriate approach to the diagnosis of lymphoproliferations in these patients by presenting illustrative cases.

New Insights into Macular Type of Primary Cutaneous B-Cell Lymphoma: Extension of the Clinical and Histopathological Patterns.

BACKGROUND: Primary cutaneous B-cell lymphoma (PCBCL) classically presents with papules, plaques, and nodules/tumors. Previous reports of PCBCL manifesting with macular lesions are scarce and focused on primary cutaneous follicle-center cell lymphoma (PCFCL). OBJECTIVES: The objective of this study was to report our experience with PCBCL presenting with erythematous macules. METHODS: Patients with low-grade PCBCL manifesting with erythematous patches, diagnosed and managed between January 2000 through December 2019 at 2 tertiary cutaneous-lymphoma outpatient clinics, were included. Clinical data were retrospectively collected, and biopsy specimens of the macules, and if present of the typical nodular/tumoral lesions, were reviewed. RESULTS: There were 14 patients, aged 16-67 years, 8 had PCFCL and 6 marginal zone lymphoma (PCMZL). All had 1-15 cm erythematous macules, mimicking: interstitial granuloma annulare/vascular tumors/early-stage folliculotropic mycosis fungoides, or presenting with figurate erythema or livedo reticularis-like/net-like pattern. In 3 patients, macules were the presenting lesions, in 2 as the sole manifestation, whereas in 12 patients, typical PCBCL lesions were observed during disease course. The macules showed in all, superficial and deep perivascular infiltrates, and in most, periadnexal infiltrates. Micronodules were observed in 11 specimens, with nodular infiltrates also observed in 4. B cells comprised the majority of the lymphocytes in only 4. Seven of 11 cases tested showed immunoglobulin heavy chain monoclonality. CONCLUSIONS: PCMZL and PCFCL may manifest with erythematous macules. Physicians should be aware of this unusual manifestation of low-grade PCBCL, which may represent a clinicopathological diagnostic pitfall.

ETV6-NCOA2 fusion induces T/myeloid mixed-phenotype leukemia through transformation of nonthymic hematopoietic progenitor cells.

Mixed-phenotype acute leukemia is a rare subtype of leukemia in which both myeloid and lymphoid markers are co-expressed on the same malignant cells. The pathogenesis is largely unknown, and the treatment is challenging. We previously reported the specific association of the recurrent t(8;12)(q13;p13) chromosomal translocation that creates the ETV6-NCOA2 fusion with T/myeloid leukemias. Here we report that ETV6-NCOA2 initiates T/myeloid leukemia in preclinical models; ectopic expression of ETV6-NCOA2 in mouse bone marrow hematopoietic progenitors induced T/myeloid lymphoma accompanied by spontaneous Notch1-activating mutations. Similarly, cotransduction of human cord blood CD34+ progenitors with ETV6-NCOA2 and a nontransforming NOTCH1 mutant induced T/myeloid leukemia in immunodeficient mice; the immunophenotype and gene expression pattern were similar to those of patient-derived ETV6-NCOA2 leukemias. Mechanistically, we show that ETV6-NCOA2 forms a transcriptional complex with ETV6 and the histone acetyltransferase p300, leading to derepression of ETV6 target genes. The expression of ETV6-NCOA2 in human and mouse nonthymic hematopoietic progenitor cells induces transcriptional dysregulation, which activates a lymphoid program while failing to repress the expression of myeloid genes such as CSF1 and MEF2C. The ETV6-NCOA2 induced arrest at an early immature T-cell developmental stage. The additional acquisition of activating NOTCH1 mutations transforms the early immature ETV6-NCOA2 cells into T/myeloid leukemias. Here, we describe the first preclinical model to depict the initiation of T/myeloid leukemia by a specific somatic genetic aberration.

Association of Preoperative Clinical, Laboratory, Imaging, and Pathologic Data With Clinically Beneficial Pathology Among Routine Splenectomy Specimens.

Importance: Previous studies have shown that uniform pathologic review of all splenectomy surgical specimens reveals new clinically actionable diagnoses only in a minority of cases. Objective: To examine whether the aggregate of clinical, laboratory, imaging, and pathologic preoperative data is associated with a clinically beneficial pathologic study for routine splenectomy surgical specimens. Design, Setting, and Participants: This single-center retrospective cohort study included all patients who underwent splenectomy from January 1, 2013, through December 31, 2018, at a single center. Clinical, imaging, and pathologic data were extracted from the institution's electronic medical records system. Data analysis was conducted from June to November 2020. Exposures: Undergoing splenectomy for trauma or diagnostic or therapeutic indications. Main Outcomes and Measures: Spleen pathology study resulting in a new medical diagnosis or change in medical management. Results: Overall, 90 patients (53 [59%] men) with a median (range) age of 59 (19-90) years underwent splenectomy for therapeutic purposes in 41 patients (45%), trauma in 24 patients (27%), diagnostic purposes in 15 patients (17%), and combined therapeutic and diagnostic purposes in 9 patients (10%). In 14 patients (15%) a new malignant neoplasm was found, and in 8 patients (9%), a new nonneoplastic medical condition was diagnosed. A new pathologic diagnosis resulted in change in medical management in 16 patients (18%). In patients without a prior diagnosis of cancer, 41 of 56 pathology biopsies (73%) were found to be normal whereas in 7 biopsies (13%), a new diagnosis of a hematologic malignant neoplasm was revealed (P < .001). Patients with clinical splenomegaly were significantly more likely to have a new pathologic diagnosis of cancer compared with patients without splenomegaly (15 of 26 [58%] vs 4 of 64 [7%]; P < .001). In 39 of 43 patients (91%) with normal presurgery imaging studies, normal spleen pathology was revealed, whereas in 14 of 17 patients (82%) with abnormal imaging studies, a new hematological malignant neoplasm was diagnosed following pathologic review of the spleen specimen (P < .001). Patients with gross abnormalities on macroscopic examination had a significantly increased likelihood of a hematological cancer diagnosis (17 of 40 [43%]) and a solid cancer diagnosis (4 [10%]) compared with patients with grossly normal specimens (4 of 49 [8%]; P < .001). Conclusions and Relevance: In this cohort study, routine pathologic review of spleen specimens was clinically beneficial in patients with splenomegaly, abnormal imaging results, a prior diagnosis of cancer, and with grossly abnormal spleens.

Congenital neutropenia with variable clinical presentation in novel mutation of the SRP54 gene.

BACKGROUND: The SRP54 (signal recognition protein 54) is a conserved component of the ribonucleoprotein complex that mediates cotranslational targeting and translocation of proteins to the endoplasmic reticulum. In 2017, mutations in the gene have been described as a cause of congenital neutropenia with or without pancreatic insufficiency, and since then, only limited cases were added to the literature. METHODS: Two patients with neutropenia underwent hematological, immunological, and genetic work-up, including lymphocyte phenotyping, immunoglobulins, and complement levels, antineutrophil and antinuclear antibodies, bone marrow FISH panel for myelodysplastic syndrome, whole-exome sequencing, and in silico proteomic analysis. RESULTS: Clinical findings in the two families revealed a wide spectrum of immunological and clinical manifestations, ranging from mild asymptomatic neutropenia during febrile illnesses to severe neutropenia and life-threatening infection requiring leg amputation. Immunological and hematological work-up showed isolated neutropenia with normal lymphocyte subpopulations, immunoglobulin and complement levels, and negative autoimmune tests. Bone marrow aspirations showed variability ranging from normal myelopoiesis to myeloid maturation arrest at the promyelocytic stage, with normal FISH panel for myelodysplastic syndrome. Genetic analysis identified a novel, de novo, in-frame deletion in the SRP54 gene, c.342-344delAAC, p.T115del. In silico proteomic analysis suggested impaired SRP54 protein function due to reduced GTP activity and stability. CONCLUSIONS: We describe congenital neutropenia with variable clinical presentation in novel mutation of the SRP54 gene.

Markers of the pre-metastatic niche "knock on the door" of metastasis-free cervical lymph nodes in patients with oral cancer.

AIM: To assess expression of some markers of the pre-metastatic niche (PMN) in lymph nodes (LNs) of oral cancer patients. MATERIALS: LNs from metastatic-free neck dissections (LN0/N0, N = 43) and metastatic-free LNs in the vicinity of metastasis-containing LNs (LN0/N+, N = 30) were immuno-histochemically stained for lysyl oxidase (LOX), fibronectin (FN), vascular-endothelial growth factor receptor (VEGFR)-1 and matrix metalloproteinase (MMP)-9. Staining was assessed as 0 (no or weak staining), 1 (strong stain in 25% cells or extracellular area), 2 (same as 1 but in up to 50%) and 3 (same as 1 but in > than 50% of cells/area). Assessment was performed in the lymph node capsule (CAP), sub-capsular sinus (SCS) and medullary sinus (MS). In addition, sections were stained with picrosirius red and examined with polarized microscopy for assessing the distribution of polarization colors of the collagen fibers in the LN capsular area. RESULTS: All examined LNs were positive for markers of the PMN. In general, the distribution and intensity of the immunoreactivity was similar between the LN0/N0 and LN0/N+, with only a few differences regarding expression of LOX in the capsule (p = 0.002) and VEGFR1 and MMP9 in the SCS (p = 0.023 and p < 0.001, respectively). Picrosirius red stain and polarized microscopy revealed a disrupted arrangement and distribution of the collagen fibers in both LN0/N0 and LN0/N + . CONCLUSION: Markers for PMN were shown for the first time to be expressed in cervical LN0/N0 from patients with oral cancer, suggesting the increased permissive pathway remotely paved by the primary oral tumor for the incoming metastatic cells.

NCAM1/FGF module serves as a putative pleuropulmonary blastoma therapeutic target.

Pleuropulmonary blastoma (PPB) is a rare pediatric lung neoplasm that recapitulates developmental pathways of early embryonic lungs. As lung development proceeds with highly regulated mesenchymal-epithelial interactions, a DICER1 mutation in PPB generates a faulty lung differentiation program with resultant biphasic tumors composed of a primitive epithelial and mesenchymal stroma with early progenitor blastomatous cells. Deciphering of PPB progression has been hampered by the difficulty of culturing PPB cells, and specifically progenitor blastomatous cells. Here, we show that in contrast with in-vitro culture, establishment of PPB patient-derived xenograft (PDX) in NOD-SCID mice selects for highly proliferating progenitor blastoma overexpressing critical regulators of lung development and multiple imprinted genes. These stem-like tumors were sequentially interrogated by gene profiling to show a FGF module that is activated alongside Neural cell adhesion molecule 1 (NCAM1). Targeting the progenitor blastoma and these transitions with an anti-NCAM1 immunoconjugate (Lorvotuzumab mertansine) inhibited tumor growth and progression providing new paradigms for PPB therapeutics. Altogether, our novel in-vivo PPB xenograft model allowed us to enrich for highly proliferating stem-like cells and to identify FGFR and NCAM1 as two key players that can serve as therapeutic targets in this poorly understood and aggressive disease.

CD137 deficiency causes immune dysregulation with predisposition to lymphomagenesis.

Dysregulated immune responses are essential underlying causes of a plethora of pathologies including cancer, autoimmunity, and immunodeficiency. We here investigated 4 patients from unrelated families presenting with immunodeficiency, autoimmunity, and malignancy. We identified 4 distinct homozygous mutations in TNFRSF9 encoding the tumor necrosis factor receptor superfamily member CD137/4-1BB, leading to reduced, or loss of, protein expression. Lymphocytic responses crucial for immune surveillance, including activation, proliferation, and differentiation, were impaired. Genetic reconstitution of CD137 reversed these defects. CD137 deficiency is a novel inborn error of human immunity characterized by lymphocytic defects with early-onset Epstein-Barr virus (EBV)-associated lymphoma. Our findings elucidate a functional role and relevance of CD137 in human immune homeostasis and antitumor responses.

Sustained Response to Imatinib in a Pediatric Patient with Concurrent Myeloproliferative Disease and Lymphoblastic Lymphoma Associated with a CCDC88C-PDGFRB Fusion Gene.

BACKGROUND: The WHO defined myeloid and lymphoid neoplasms (MLN) with eosinophilia associated with PDGFRB, PDGFRA, FGFR1 rearrangements as a new entity in 2016. PDGFRB-rearranged MLN sensitive to imatinib were described in adult patients. We report the first pediatric patient with PDGFRB-rearranged myeloproliferative disorder associated with T-lymphoblastic lymphoma bearing the t(5; 14)(q33;q32) translocation who was successfully treated with imatinib only. Methods/Aims: Analysis of bone marrow and peripheral blood cells by fluorescent in situ hybridization identified the PDGFRB partner as CCDC88C. Whole genome sequencing of the patient's DNA identified the exact junction site, confirmed by PCR amplification and Sanger sequencing. A real-time quantitative PCR assay was designed to quantify the fused CCDC88C-PDGFRB product. RESULTS: A 2.5-year-old boy was diagnosed with myeloproliferative disorder and eosinophilia associated with lymphoblastic lymphoma both bearing the CCDC88C-PDGFRB fusion. Imatinib therapy resulted in rapid clinical, hematological, and cytogenetic response. Molecular response to treatment was monitored by a real-time PCR assay specific for the CCDC88C- PDGFRB fusion. CONCLUSION: This is the first description of MLN with eosinophilia in the pediatric age group. Response to treatment with imatinib only was monitored by specific quantitative PCR assay with sustained remission lasting 5.5 years from diagnosis.

In Vivo Expansion of Cancer Stemness Affords Novel Cancer Stem Cell Targets: Malignant Rhabdoid Tumor as an Example.

Cancer stem cell (CSC) identification relies on transplantation assays of cell subpopulations sorted from fresh tumor samples. Here, we attempt to bypass limitations of abundant tumor source and predetermined immune selection by in vivo propagating patient-derived xenografts (PDX) from human malignant rhabdoid tumor (MRT), a rare and lethal pediatric neoplasm, to an advanced state in which most cells behave as CSCs. Stemness is then probed by comparative transcriptomics of serial PDXs generating a gene signature of epithelial to mesenchymal transition, invasion/motility, metastasis, and self-renewal, pinpointing putative MRT CSC markers. The relevance of these putative CSC molecules is analyzed by sorting tumorigenic fractions from early-passaged PDX according to one such molecule, deciphering expression in archived primary tumors, and testing the effects of CSC molecule inhibition on MRT growth. Using this platform, we identify ALDH1 and lysyl oxidase (LOX) as relevant targets and provide a larger framework for target and drug discovery in rare pediatric cancers.

Low rate of spleen involvement in sporadic Burkitt lymphoma at staging on PET-CT.

BACKGROUND: Burkitt lymphoma is a highly aggressive B cell non-Hodgkin lymphoma. Cross-sectional imaging techniques that are used to detect liver and spleen involvement by lymphoma have high rates of false negative and false positive findings, and as such may reduce the accuracy of staging. PURPOSE: This retrospective study evaluated the use of FDG PET-CT in determining splenic involvement at staging, in a relatively large cohort of adult patients with the sporadic form of Burkitt lymphoma (SBL). PATIENTS AND METHODS: All adult patients who underwent FDG PET-CT for staging of SBL at one medical center during 2005-2014 were enrolled for this retrospective study. RESULTS: Data were analyzed of 20 patients, with median age 49 years; 17 were male. PET-CT revealed highly intense FDG uptake, mean SUV max 11.4 ± 7.49 (range 4.3-38) in various tissues. None of the 20 patients had either focal or diffuse increased uptake of FDG in the spleen parenchyma. In 2 patients, there were highly FDG-avid soft tissue masses adjacent to the spleen, both in the context of direct peritoneal disease extension. CONCLUSION: The spleen is rarely involved in SBL at the time of staging, according to PET-CT, except in cases with direct extension from adjacent peritoneal mass. The low rate of spleen involvement according to PET-CT may serve as a specific characteristic of SBL. Larger-scale clinical studies incorporating PET-CT scans in SBL are needed to confirm our observation.

Elderly apolipoprotein E­/­ mice with advanced atherosclerotic lesions in the aorta do not develop Alzheimer's disease-like pathologies.

Atherosclerosis and Alzheimer's disease (AD) are a major cause of morbidity and mortality in Western societies. These diseases share common risk factors, which are exhibited in old age, including hypertension, diabetes, hypercholesterolemia and apolipoprotein (Apo) ε4 allele. We previously demonstrated that factor XI (FXI) deficiency in mice reduced the atherosclerotic plaque area in coronary sinuses and the aortic arch. This led us to investigate whether FXI deficiency in elderly ApoE knockout (KO) mice would decrease pathological alterations compatible with atherosclerosis and AD. The present study used ApoE/factor XI double KO (ApoE/FXI DKO) mice aged 64 weeks and age­matched ApoE KO mice to serve as a control group. The ApoE KO mice developed an advanced atherosclerotic lesion area in the aortic arch, which was reduced by 33% in the DKO mice. However, neither atherosclerosis nor AD­associated pathological alterations in the elderly mice brains were observed in either the DKO mice or the ApoE KO mice. The results advocate a dichotomy between the brain and peripheral blood vessels. Therefore, the ApoE KO and DKO mice cannot serve as mouse models for studying AD or pathological brain changes compatible with atherosclerosis. The mechanism by which ApoE KO protects against brain pathology should be further studied as it may prove helpful for future treatment of senile dementia.

Disruption of Thrombocyte and T Lymphocyte Development by a Mutation in ARPC1B.

Regulation of the actin cytoskeleton is crucial for normal development and function of the immune system, as evidenced by the severe immune abnormalities exhibited by patients bearing inactivating mutations in the Wiskott-Aldrich syndrome protein (WASP), a key regulator of actin dynamics. WASP exerts its effects on actin dynamics through a multisubunit complex termed Arp2/3. Despite the critical role played by Arp2/3 as an effector of WASP-mediated control over actin polymerization, mutations in protein components of the Arp2/3 complex had not previously been identified as a cause of immunodeficiency. Here, we describe two brothers with hematopoietic and immunologic symptoms reminiscent of Wiskott-Aldrich syndrome (WAS). However, these patients lacked mutations in any of the genes previously associated with WAS. Whole-exome sequencing revealed a homozygous 2 bp deletion, n.c.G623DEL-TC (p.V208VfsX20), in Arp2/3 complex component ARPC1B that causes a frame shift resulting in premature termination. Modeling of the disease in zebrafish revealed that ARPC1B plays a critical role in supporting T cell and thrombocyte development. Moreover, the defects in development caused by ARPC1B loss could be rescued by the intact human ARPC1B ortholog, but not by the p.V208VfsX20 variant identified in the patients. Moreover, we found that the expression of ARPC1B is restricted to hematopoietic cells, potentially explaining why a mutation in ARPC1B has now been observed as a cause of WAS, whereas mutations in other, more widely expressed, components of the Arp2/3 complex have not been observed.

The impact of IgG-4-ROD on the diagnosis of orbital tumors: A retrospective analysis.

This study was to determine the prevalence of immunoglobulin G4 (IgG4)-related orbital disease (IgG4-ROD) among patients who have previously undergone biopsy and were diagnosed to have idiopathic orbital inflammatory disease (IOID) or orbital lymphoproliferative disease (OLD), namely, lymphoma and benign reactive lymphoid hyperplasia (BRLH). This is a retrospective cross-sectional study. The charts and slides of all patients who underwent biopsies and were histopathologically diagnosed to have either IOID or OLD were reviewed. Demographics, clinical features, initial histopathological diagnoses, treatment received, and final outcome were noted. Using the diagnostic criteria for diagnosis for IgG4 disease, those cases that would classify as "possible IgG4-related disease (IgG4-RD)" were reviewed, reclassified, and reassigned a diagnosis of IgG4-ROD. We reviewed 105 patients' clinical charts. Of these 105 patients, upon reviewing the histopathology, 18 (17.15%) patients were found to fit the diagnostic criteria for possible IgG4-ROD. Of these 18 patients who were now reassigned the diagnosis of IgG4-ROD, the most common previous histopathological diagnosis was found to be IOID, for eight patients (44%), then BRLH, which was noted in five patients (27.8%), followed by lymphoma, which was noted in two patients (11.1%). Previously diagnosed cases of IOID and OLD were found to fulfill the criteria for IgG4-ROD. Given the advent of recent diagnostic and histopathological techniques, all cases of suspected IOID and OLD should be screened for IgG4-ROD and all previously diagnosed cases must be closely followed up, given the systemic implication of IgG4-RD. Histopathological reassessment of previously diagnosed cases may be considered.

Laparoscopic Lymph Node Biopsy: Efficacy and Advantages.

BACKGROUND: Diagnosis of abdominal lymphadenopathy is challenging when not accompanied by peripheral lymphadenopathy. Computed tomography-guided core-needle biopsy has largely replaced open procedures in recent years, but this approach is limited by access to the anatomic region and the amount of tissue acquired. OBJECTIVES: To demonstrate the feasibility of the laparoscopic approach in obtaining abdominal lymph node biopsies and to evaluate the diagnostic adequacy of the technique. METHODS: We reviewed the data of patients who underwent laparoscopic lymph node biopsy between 2014 and 2014 in our department. Demographics, intra-operative parameters and postoperative course were examined, as were histological reports. Postoperative complications were categorized according to the Clavien-Dindo(CD) classification. RESULTS: Between 2004 and 2014, 57 laparoscopic biopsies were performed for intra-abdominal lymphadenopathy. One case was a repeated attempt due to limited histologic material. The mean age was 49.5 ± 19.6 years. There were two conversions to open laparotomy, one due to small bowel injury and the other due to a sizable mass. Overall, 56 cases had full clinical data: 48 cases (85.7%) had CD=0, six (10.7%) had CD=1, one postoperative severe complication (CD=3) and one mortality (CD=5), which was related to preexisting hepatic insufficiency. Mean hospital stay was 1.6 days. Overall, adequate tissue samples were acquired in 96.7% and only 3 of these cases resulted in inconclusive diagnoses. CONCLUSIONS: Laparoscopic lymph node biopsy is a viable alternative to the currently available methods of tissue retrieval. It provides an access for nodes which are inaccessible percutaneously, and may allow a superior diagnostic yield.

Correction: Overcoming Resistance of Cancer Cells to PARP-1 Inhibitors with Three Different Drug Combinations.

[This corrects the article DOI: 10.1371/journal.pone.0155711.].

Mutations in STN1 cause Coats plus syndrome and are associated with genomic and telomere defects.

The analysis of individuals with telomere defects may shed light on the delicate interplay of factors controlling genome stability, premature aging, and cancer. We herein describe two Coats plus patients with telomere and genomic defects; both harbor distinct, novel mutations in STN1, a member of the human CTC1-STN1-TEN1 (CST) complex, thus linking this gene for the first time to a human telomeropathy. We characterized the patients' phenotype, recapitulated it in a zebrafish model and rescued cellular and clinical aspects by the ectopic expression of wild-type STN1 or by thalidomide treatment. Interestingly, a significant lengthy control of the gastrointestinal bleeding in one of our patients was achieved by thalidomide treatment, exemplifying a successful bed-to-bench-and-back approach.

Overcoming Resistance of Cancer Cells to PARP-1 Inhibitors with Three Different Drug Combinations.

Inhibitors of poly[ADP-ribose] polymerase 1 (PARPis) show promise for treatment of cancers which lack capacity for homologous recombination repair (HRR). However, new therapeutic strategies are required in order to overcome innate and acquired resistance to these drugs and thus expand the array of cancers that could benefit from them. We show that human cancer cell lines which respond poorly to ABT-888 (a PARPi), become sensitive to it when co-treated with vorinostat (a histone deacetylase inhibitor (HDACi)). Vorinostat also sensitized PARPis insensitive cancer cell lines to 6-thioguanine (6-TG)-a drug that targets PARPis sensitive cells. The sensitizing effect of vorinostat was associated with increased phosphorylation of eukaryotic initiation factor (eIF) 2α which in and of itself increases the sensitivity of cancer cells to ABT-888. Importantly, these drug combinations did not affect survival of normal fibroblasts and breast cells, and significantly increased the inhibition of xenograft tumor growth relative to each drug alone, without affecting the mice weight or their liver and kidney function. Our results show that combination of vorinostat and ABT-888 could potentially prove useful for treatment of cancer with innate resistance to PARPis due to active HRR machinery, while the combination of vorinostat and 6-TG could potentially overcome innate or acquired resistance to PARPis due to secondary or reversal BRCA mutations, to decreased PARP-1 level or to increased expression of multiple drug resistant proteins. Importantly, drugs which increase phosphorylation of eIF2α may mimic the sensitizing effect of vorinostat on cellular response to PARPis or to 6-TG, without activating all of its downstream effectors.