Sodium-glucose cotransporter 2 inhibitors and the cancer patient: from diabetes to cardioprotection and beyond.

Sodium-glucose cotransporter 2 inhibitors (SGLT2i), a new drug class initially designed and approved for treatment of diabetes mellitus, have been shown to exert pleiotropic metabolic and direct cardioprotective and nephroprotective effects that extend beyond their glucose-lowering action. These properties prompted their use in two frequently intertwined conditions, heart failure and chronic kidney disease. Their unique mechanism of action makes SGLT2i an attractive option also to lower the rate of cardiac events and improve overall survival of oncological patients with preexisting cardiovascular risk and/or candidate to receive cardiotoxic therapies. This review will cover biological foundations and clinical evidence for SGLT2i modulating myocardial function and metabolism, with a focus on their possible use as cardioprotective agents in the cardio-oncology settings. Furthermore, we will explore recently emerged SGLT2i effects on hematopoiesis and immune system, carrying the potential of attenuating tumor growth and chemotherapy-induced cytopenias.

Posttransplant Autoimmune Hemolytic Anemia with Anti-D Specificity Successfully Treated with Daratumumab: A Case Report.

Introduction: Autoimmune hemolytic anemia (AIHA) occurs in 0.7-5.6% of patients undergoing hematopoietic stem cell transplantation, especially from unrelated or haploidentical donor or after lympho-depleted transplant; the majority of cases are represented by warm AIHA, occurring in a full donor chimerism setting. Standard treatments (corticosteroids, intravenous immunoglobulin, splenectomy, rituximab, cyclophosphamide, plasma exchange) lead to lower response rates than those reported in primary AIHA. Daratumumab use has been proposed in many autoimmune conditions (immune thrombocytopenic purpura, aplastic anemia, thrombotic thrombocytopenic purpura, systemic lupus erythematosus, multiple sclerosis), but only few reports have been published on its use for post-HSCT AIHA, mainly in pediatric patients. Case Presentation: We report the successful use of daratumumab in a 68-year-old patient, suffering from post-HSCT AIHA. Five months after Rh-mismatched HSCT, the patient was diagnosed with anti-D AIHA. After first-line treatment (oral prednisone, rituximab, and plasma exchange) failure, being still transfusion-dependent with symptomatic anemia, he underwent treatment with daratumumab, achieving both clinical and laboratory responses. Discussion: Daratumumab may represent a safe and effective alternative to conventional immunosuppressive therapy, and it deserves further investigations.

Allogeneic cord blood transfusions prevent fetal haemoglobin depletion in preterm neonates. Results of the CB-TrIP study.

Repeated red blood cell (RBC) transfusions in preterm neonates are associated with poor outcome and increased risk for prematurity-associated diseases. RBC transfusions cause the progressive replacement of fetal haemoglobin (HbF) by adult haemoglobin (HbA). We monitored HbF levels in 25 preterm neonates until 36 weeks of post-menstrual age (PMA); patients received RBC units from allogeneic cord blood (cord-RBCs) or from adult donors (adult-RBCs), depending on whether cord-RBCs were available. Primary outcome was HbF level at PMA of 32 weeks. Twenty-three neonates survived until this age: 14 received no transfusions, two only cord-RBCs, three only adult-RBCs and four both RBC types. HbF levels in neonates transfused with cord-RBCs were significantly higher than in neonates receiving adult-RBCs (P < 0·0001) or both RBC types (P < 0·0001). Superimposable results were obtained at PMA of 36 weeks. Every adult-RBCs transfusion increased the risk for an HbF in the lowest quartile by about 10-fold, whereas this effect was not evident if combined adult- and cord-RBCs were evaluated. Overall, these data show that transfusing cord-RBCs can limit the HbF depletion caused by conventional RBC transfusions. Transfusing cord blood warrants investigation in randomised trials as a strategy to mitigate the severity of retinopathy of prematurity (NCT03764813).

Umbilical cord blood: Current uses for transfusion and regenerative medicine.

The past 20 years of experience with umbilical cord blood transplantation have demonstrated that cord blood is effective in the treatment of a spectrum of diseases, including hematological malignancies, bone marrow failure, hemoglobinopathies, and inborn errors of metabolism. However, only a few number of umbilical cord blood units collected have a cell content adequate for an allogenic hematopoietic stem cell transplantation. In the meanwhile, there is an increasing interest in exploiting cord blood derivatives in different fields. In this review, we will summarize the most recent updates on clinical applications of umbilical cord blood platelet derivatives for regenerative medicine, and we will revise the literature concerning the use of umbilical cord blood for autologous or allogeneic transfusion purposes. The methodological aspect and the biological characteristics of these products also will be discussed.

Preoperative autologous blood donation in adult bone marrow donors: reappraisal of a single-centre experience.

To avoid risk for allogeneic transfusions in healthy bone marrow (BM) donors, 1-2 preoperative autologous blood donations (PAD) are usually collected before the BM harvest. We analysed the haematological parameters in BM donors before and after the harvest, to assess the efficacy of this practice in limiting the postharvest anaemia. Overall, 102 consecutive donors underwent BM harvest preceded by one (26 cases) or two PAD (76 cases), which were infused during BM collection. We analysed the parameters related to donors, PAD timing and BM graft characteristics. PAD induced a significant decrease in Hb (from 14·6 g/dl, IQ range 13·3-15·5 to12·9 g/dl, IQ range 11·8-13·9; P < 0·0001) in all donors, with a median Hb loss at day -1 of 10·9% (IQ range 6·8-14·2). The PAD-related Hb decrease was independent of sex or number of PAD, and was inversely related to the time elapsed from first or last PAD. In comparison with values recorded at day-1, BM harvest produced an additional Hb decrease, accounting for a median Hb loss of 18·9% (IQ range 14·9-24·4). Overall, in comparison with pre-PAD values, Hb levels at day +1 were reduced of 28·9% (IQ range 23·6-32·2), independently if donors had 1 or 2 PAD reinfused. In conclusion, these data show that two PAD do not carry any advantage over one PAD. An eventual benefit of PAD can be achieved only if an adequate interval between PAD and BM harvest elapses. Prospective randomized studies could be worth to establish if any role for PAD does exist in BM donors.

Pros and Cons of Cryopreserving Allogeneic Stem Cell Products.

The COVID-19 pandemic has precipitously changed the practice of transplanting fresh allografts. The safety measures adopted during the pandemic prompted the near-universal graft cryopreservation. However, the influence of cryopreserving allogeneic grafts on long-term transplant outcomes has emerged only in the most recent literature. In this review, the basic principles of cell cryopreservation are revised and the effects of cryopreservation on the different graft components are carefully reexamined. Finally, a literature revision on studies comparing transplant outcomes in patients receiving cryopreserved and fresh grafts is illustrated.

Hematopoietic stem cell transplantation: an Italian monocentric experience on the health assessment and eligibility of adult-related donors.

Introduction: Indications for HSCT are increasing worldwide, paralleled by a growing demand for donors of therapeutic cells. Methods: Herein, we report our real-world experience of adult HPC donor assessment during a 5-year study period (2018-2023): we have retrospectively revised data of 455 potential related stem cell donors, consecutively evaluated at our center. Donor medical history was assessed by a questionnaire and an interview with a trained physician experienced in donation procedures to evaluate donor fitness and medical history. Pre-existing health disorders were fully investigated. Behavioral risk factors for communicable infectious diseases were also routinely explored. Results and discussion: Overall, 351 donors were finally assessed as eligible for HPC donation, and 233 underwent stem cell collection, 158 through apheresis from mobilized peripheral blood, and 75 through bone marrow harvest. Among them, 27 donors were selected despite the presence of pre-existing health conditions, which would be potential exclusion criteria for unrelated donors: 16 suffered from well-controlled cardiovascular diseases (CVD) and 11 from allergic diathesis. Most of the selected donors with pre-existing disorders were candidates for apheresis HPC collection (21, 77.8%), while only six (22.2%) underwent BM harvest. We then analyzed the data relative to the corresponding 233 allogeneic HSCT to explore if the presence of pre-existing diseases in the donors could show any association with transplant characteristics. Transplants from CVD and allergy donors showed no significant disparities in comparison with those from healthy donors. A significant difference emerged regarding the disease severity, with a higher proportion of patients with high/very high disease risk index (DRI) among those receiving grafts from CVD donors (68.7% in transplants from CVD donors versus 36.0% in transplants from healthy donors, p=0.005). Multivariate analysis confirmed that high/very high DRI patients had an increased probability of receiving donations from CVD donors (OR, 4.89; 95%CI, 1.15-20.86; p=0.031). Among donors with well-controlled pre-existing conditions, no adverse events were recorded during stem cell collection or at follow-up. Our results suggest that in patients at high risk for relapse requiring a prompt allogeneic transplant, a familiar donor might be accepted for HPC apheresis donation on less strict criteria than unrelated donors, without risk for both donor and patient.

Cord blood transfusions in extremely low gestational age neonates to reduce severe retinopathy of prematurity: results of a prespecified interim analysis of the randomized BORN trial.

BACKGROUND: Preterm infants are at high risk for retinopathy of prematurity (ROP), with potential life-long visual impairment. Low fetal hemoglobin (HbF) levels predict ROP. It is unknown if preventing the HbF decrease also reduces ROP. METHODS: BORN is an ongoing multicenter double-blinded randomized controlled trial investigating whether transfusing HbF-enriched cord blood-red blood cells (CB-RBCs) instead of adult donor-RBC units (A-RBCs) reduces the incidence of severe ROP (NCT05100212). Neonates born between 24 and 27 + 6 weeks of gestation are enrolled and randomized 1:1 to receive adult donor-RBCs (A-RBCs, arm A) or allogeneic CB-RBCs (arm B) from birth to the postmenstrual age (PMA) of 31 + 6 weeks. Primary outcome is the rate of severe ROP at 40 weeks of PMA or discharge, with a sample size of 146 patients. A prespecified interim analysis was scheduled after the first 58 patients were enrolled, with the main purpose to evaluate the safety of CB-RBC transfusions. RESULTS: Results in the intention-to-treat and per-protocol analysis are reported. Twenty-eight patients were in arm A and 30 in arm B. Overall, 104 A-RBC units and 49 CB-RBC units were transfused, with a high rate of protocol deviations. A total of 336 adverse events were recorded, with similar incidence and severity in the two arms. By per-protocol analysis, patients receiving A-RBCs or both RBC types experienced more adverse events than non-transfused patients or those transfused exclusively with CB-RBCs, and suffered from more severe forms of bradycardia, pulmonary hypertension, and hemodynamically significant patent ductus arteriosus. Serum potassium, lactate, and pH were similar after CB-RBCs or A-RBCs. Fourteen patients died and 44 were evaluated for ROP. Ten of them developed severe ROP, with no differences between arms. At per-protocol analysis each A-RBC transfusion carried a relative risk for severe ROP of 1.66 (95% CI 1.06-2.20) in comparison with CB-RBCs. The area under the curve of HbF suggested that HbF decrement before 30 weeks PMA is critical for severe ROP development. Subsequent CB-RBC transfusions do not lessen the ROP risk. CONCLUSIONS: The interim analysis shows that CB-RBC transfusion strategy in preterm neonates is safe and, if early adopted, might protect them from severe ROP. TRIAL REGISTRATION: Prospectively registered at ClinicalTrials.gov on October 29, 2021. Identifier number NCT05100212.

Red Blood Cell Exchange as a Valid Therapeutic Approach for Pregnancy Management in Sickle Cell Disease: Three Explicative Cases and Systematic Review of Literature.

Pregnancy in women with sickle cell disease (SCD) is a high-risk situation, especially during the third trimester of gestation and in the post-partum period, due to chronic hypoxia and vaso-occlusive phenomena occurring in the maternal-fetal microcirculation: as a result, unfavorable outcomes, such as intra-uterine growth restriction, prematurity or fetal loss are more frequent in SCD pregnancies. Therefore, there is a consensus on the need for a strict and multidisciplinary follow-up within specialized structures. Transfusion support remains the mainstay of treatment of SCD pregnancies, whereas more targeted modalities are still controversial: the benefit of prophylactic management, either by simple transfusions or by automated red blood cell exchange (aRBCX), is not unanimously recognized. We illustrate the cases of three SCD pregnant patients who underwent aRBCX procedures at our institution in different clinical scenarios. Moreover, we carried out a careful literature revision to investigate the management of pregnancy in SCD, with a particular focus on the viability of aRBCX. Our experience and the current literature support the use of aRBCX in pregnancy as a feasible and safe procedure, provided that specialized equipment and an experienced apheresis team is available. However, further research in this high-risk population, with appropriately powered prospective trials, is desirable to refine the indications and timing of aRBCX and to confirm the advantages of this approach on other transfusion modalities.

Day -1 CD34+ Cells and Platelet Count Predict the Number of Apheresis in Poor-Mobilizer Patients Rescued by Plerixafor.

Plerixafor is widely used as up-front treatment with G-CSF to enhance peripheral blood hematopoietic stem cell output in patients failing previous mobilizations. Less frequently, plerixafor is used to rescue an unsatisfactory mobilization following chemotherapy (CT) and G-CSF. This study investigates if pre-collection factors affect the CD34+ cell harvest in chemotherapy and G-CSF mobilizations rescued by plerixafor. Clinical and hematological data relative to patients, mobilization, and apheresis products were retrospectively examined. The outcome was completing a target cell dose ≥ 2 × 106 CD34+ cells/kg at first apheresis. The effect exerted on the outcome by patient- and disease-related factors was investigated by univariate and multivariate logistic regression analysis. The analysis included data from 42 patients affected by hematological (39 patients) and non-hematological malignancies (three patients). Twenty-nine patients (69%) attained the target cell dose at first apheresis. Twelve out of the remaining 13 patients received an additional plerixafor administration, and all accomplished the transplant dose at a second apheresis procedure. Day -1 CD34+ PB count (OR1.46, 95% CI 1.1-1.9, p = 0.008) and platelet count (OR1.0, 95% CI 1.0-1.0, p = 0.033) predicted the achievement of the target dose at first apheresis, independently of pre-mobilization CT, radiation therapy, and disease status at mobilization. At ROC curve analysis, the best cut-off value predicting the successful collection at first apheresis was 7.5/µL for Day -1 CD34+ cell count (AUC 0.830, 0.69 sensitivity, and 0.92 specificity) and 75 × 109/L for Day -1 platelet count (AUC = 0.736, 0.65 sensitivity and 0.85 specificity). In conclusion, on-demand plerixafor rescue allows a successful stem cell collection, irrespectively of disease type and status, prior CT lines, and radiation exposure. Pre-apheresis CD34+ cells and platelet count predict the need for one or two aphereses.

Differences in Cerebral Tissue Oxygenation in Preterm Neonates Receiving Adult or Cord Blood Red Blood Cell Transfusions.

Importance: Repeated transfusions in preterm neonates with anemia of prematurity replace fetal hemoglobin (HbF) with adult Hb (HbA), which has a low oxygen affinity. The reduction of HbF is associated with a higher incidence of retinopathy of prematurity (ROP). Objective: To assess whether HbF and HbA are differently associated with cerebral tissue oxygenation in preterm neonates. Design, Setting, and Participants: This cohort study was a single-center, pilot study on cerebral oxygenation kinetics in preterm neonates with a gestational age between 24.0 weeks and 27.9 weeks who were admitted to the neonatal intensive care unit of Policlinico Universitario A. Gemelli IRCCS from December 27, 2021, to May 15, 2023. This study was ancillary to the ongoing, double-blind, multicenter Umbilical or Adult Donor Red Blood Cells in Extremely Low Gestational Age Neonates and Retinopathy of Prematurity (BORN) randomized clinical trial. The BORN trial outcome was ROP severity in neonates randomized to receive standard packed red blood cell (PRBC) transfusions obtained from RBCs of adult donors (A-RBCs) or from cord blood (CB-RBCs). According to standard procedures at the institute's neonatal intensive care unit, patients concurrently received continuous cerebral near-infrared spectroscopy (NIRS) monitoring. This cohort study was not prespecified in the trial protocol. Exposure: Transfusion with A-RBCs or CB-RBCs. Main Outcomes and Measures: The main outcome was the kinetics of cerebral regional oxygen saturation (crSO2) and cerebral fraction of tissue oxygen extraction (cFTOE) associated with A-RBC or CB-RBC transfusions. Cerebral NIRS monitoring was performed by neonatologists and nurses, who were blinded to the PRBC type. The NIRS monitoring was conducted starting with the blood product order, during transfusion, and for the subsequent 24 hours after transfusion completion. The mean treatment effects of A-RBCs or CB-RBCs were quantified using a linear mixed model for repeated measures. Results: Of 23 randomized neonates, 17 (11 male [64.7%]; median gestational age at birth, 25.6 weeks [IQR, 25.3-26.1 weeks]) with a median birth weight of 840 g (IQR, 580-900 g) were included in the study; NIRS was evaluated for 42 transfusion episodes, of which 22 were A-RBCs and 20 were CB-RBCs. Globally considering all posttransfusion time points, the overall crSO2 covariate-adjusted mean after CB-RBC transfusions was 5.27% lower (95% CI, 1.20%-9.34%; P = .01) than that after A-RBC transfusions, while the cFTOE after CB-RBC transfusions was 6.18% higher (95% CI, 1.66%-10.69%; P = .009) than that after A-RBCs. Conclusions and Relevance: The findings of this cohort study suggest that A-RBC transfusions may be associated with more oxygen delivery to cerebral tissues of preterm neonates than transfusions from CB-RBCs. This finding may explain the previously observed association between low HbF and high ROP risk. It also suggests that use of CB to meet the RBC transfusion needs of neonates with a gestational age of less than 28 weeks may protect cerebral tissues from overexposure to oxygen.

Single shot of intravenous iron in cardiac surgery: The ICARUS study.

BACKGROUND: Iron deficiency (ID), with or without anemia, is commonly observed among patients scheduled for cardiac surgery. We investigated if screening ID in the immediate preoperative period and treating ID patients regardless of anemia could reduce perioperative transfusion requirements. METHODS: This is an observational single-center propensity score-matched study including candidates to elective cardiac surgery prospectively and retrospectively enrolled. Prospectively enrolled patients were screened for ID at hospital admission: if ferritin was ≤100 µg/L or ≤ 300 µg/L with transferrin saturation index ≤20% they received intravenous ferric carboxymaltose, B12-vitamin, and folic acid. A retrospective series of patients not screened for ID and matched for gender, type of surgery, BMI, Goudie transfusion risk score, hemoglobin level, and red blood cell (RBC) indices, served as controls. The primary outcome was the proportion of patients requiring ≤1 packed RBC (pRBC) unit within day 7 or discharge The main secondary outcomes were intraoperative and postoperative pRBC transfusions, duration of hospitalization, and cost-effectiveness of ID screening and treatment. RESULTS: We included 479 prospective and 833 retrospective cases: 442 patients screened for ID and 442 matched controls with unknown iron status were analyzed. ID was observed in 196 patients (44.3%) and iron was administered 1 day (IQR 1-2) before surgery. Overall, 76.9% of patients in the prospective group and 69.7% of controls received ≤1 pRBC transfusion (p = 0.014). The risk for multiple transfusions was lower in patients screened for ID (OR 0.689, 95% CI 0.510-0.930). Despite similar Hb levels at day 7, patients in the prospective group received fewer postoperative pRBC transfusions (p < 0.001) and had a shorter hospital length of stay (p < 0.001). Globally, hospitalization costs were lower in patients screened and treated for ID. CONCLUSIONS: Short-term pre-operative iron therapy is associated with a reduction in postoperative transfusions in anemic and non-anemic ID cardiac surgery patients and has a favorable impact on hospitalization costs. CLINICAL TRIAL REGISTRATION: NCT04744181.

Acute Promyelocytic Leukemia in a Woman with Thalassemia Intermedia: Case Report and Review of Literature on Hematological Malignancies in ß-Thalassemia Patients.

Patients affected by transfusion-dependent ß-thalassemia are prone to developing several clinical complications, mostly related to the iron overload. We report the case of a patient affected by transfusion-dependent ß-thalassemia (TDT) developing acute promyelocytic leukemia (APL). In our case, the therapeutic management was significantly complicated not only by myocardial dysfunction, but also by the occurrence of the differentiation syndrome following all-trans retinoic acid (ATRA) administration. We carried out a careful revision of the current literature on the occurrence of hematological malignancies in ß-thalassemia patients to investigate the major complications so far described. APL occurrence in ß-thalassemia patients has been very rarely reported, and our experience suggests that TDT patients suffering pre-existing comorbidities may develop a potentially fatal complication during ATRA therapy.

Transfusion-Free Survival Predicts Severe Retinopathy in Preterm Neonates.

Repeated red blood cell (RBC) transfusions are thought to increase the risk for retinopathy of prematurity (ROP), likely due to a critical fetal hemoglobin (HbF) reduction. In this study, we investigated if the postmenstrual age (PMA) of neonates at transfusion influences the risk for ROP. We estimated the cumulative transfusion-free survival (TFS) in a series of 100 preterm neonates receiving one or more RBC units. TFS was calculated by censoring patients at first transfusion and expressing the time between birth and transfusion as either PMA or postnatal day. Then, we investigated if TFS predicted the occurrence of severe ROP, defined as ROP stage 3 or higher. We found that neonates with severe ROP displayed a significantly shorter TFS expressed according to their PMA (p = 0.001), with similar TFS according to postnatal days. At receiver operating characteristic (ROC) curve analysis, receiving an RBC unit before week 28 of PMA predicted severe ROP with a sensitivity of 64% and a specificity of 78%. In addition, receiving a second RBC unit before the PMA of 29 weeks predicted severe ROP with a sensitivity of 75% and a specificity of 69%. At multivariate analysis, PMA at the second transfusion was even more informative than at first transfusion and outperformed all other variables in predicting severe ROP, with an odds ratio of 4.554 (95% CI 1.332-15.573, p = 0.016). Since HbF decrease is greater after multiple RBC transfusions, it is conceivable that neonates receiving more than one unit before the PMA of 29 weeks may be exposed to a greater disturbance of retinal vascularization. Any strategy aimed at preventing the critical HbF decrease at this low age might potentially reduce the risk for severe ROP.

Immunohistochemical evaluation of STAT3-p-tyr705 expression in feline mammary gland tumours and correlation with histologic grade.

STAT3 (signal transducer and activator of transcription 3) is a cytoplasmic transcription factor that plays a role in the G1 to S phase cell-cycle transition and is induced by cytokines and growth factors. The expression of STAT3 phosphorylated on tyrosine 705 (STAT3-p-tyr705) in normal, hyperplastic and neoplastic feline mammary gland tissue was assessed by immunohistochemistry in 45 cats. The samples included 4 normal mammary non-lactating tissues, 9 hyperplastic tissues (5 fibroepithelial hyperplasia and 4 lobular epithelial hyperplasia), 2 benign tumours (1 complex adenoma, and 1 simple adenoma), and 30 carcinomas (18 simple tubular papillary, 6 simple tubular, 2 simple solid, 3 cribriform, and 1 adenosquamous carcinoma). For immunohistochemistry, tissue sections were incubated with an anti-STAT3-p-tyr705 monoclonal antibody and visualized with EnVision-DAB polymer. STAT3-p-tyr705 positivity was quantified in a semi-quantitative manner. All positive samples showed cytoplasmic and/or nuclear positivity. Normal non-lactating mammary tissue showed a low number of positive cells, similar to hyperplastic tissue. In neoplastic tissues, a high number of positive cells with a moderate to intense reaction was observed. Moreover, a correlation was observed between nuclear positivity for STAT3-p-tyr705 and histologic grade (P=0.013; r=0.447), tubular formation (P=0.043; r=0.820), and mitotic activity (P<0.0001; r=0.689). In contrast, no such correlations were observed for cytoplasmic reactivity of STAT3-p-tyr705. A significant difference was observed between malignant lesions and hyperplasia with regards to expression of STAT3-p-tyr 705 in the cytoplasm (P=0.008; U=59.00) and nuclei (P=0.002; U=47.00). These results confirm previous our data and reinforce the potential role of STAT3 in malignancy as reported for human breast cancer and other sporadic tumours.

Transcriptional properties of feline p53 and its tumour-associated mutants: a yeast-based approach.

Mutations at the tumour suppressor gene TP53 are associated with nearly half of human cancers, but they appear to be rare ( approximately 10%) in feline neoplasms. The reasons for this difference are presently unclear but might be related to evolutionary divergence of p53 functions. To begin exploring this issue, we developed a yeast-based functional assay to measure the transcriptional ability of wild-type (wt) or mutant feline p53 (fe_p53) in comparison with human or murine p53 (hu_p53, mo_p53). fe_p53 cDNA was cloned and expressed in a panel of yeast reporter strains engineered to contain the ADE2 or the luciferase gene under p53 control via different p53 response elements. We established that wt fe_, hu_ and mo_p53 can act as transcription factors in yeast with overlapping DNA sequence specificities. Random mutagenesis and phenotypic evaluation of fe_ and hu_p53 cDNAs was also performed, revealing equal susceptibility to deleterious mutations. Five tumour-associated fe_p53 mutants exhibited a similar impact on the transactivation capacity (partial or complete loss) compared to the corresponding hu_p53 mutants. Given the high conservation of the intrinsic functional properties of fe_p53, further studies will be needed to clarify the role of p53 in feline carcinogenetic pathways.