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6052 citation(s) found for "Vu, Peter".

Intergroup randomized phase III study of adjuvant FOLFIRI, FOLFOX, or 5-FU/leucovorin for stage II/III rectal cancer: ECOG-ACRIN E3201
Kam, Audrey E , Meropol, Neal J. , Giantonio, Bruce J. , Diasio, Robert B. , Flynn, Patrick J. , Catalano, Paul J. , Hartner, Lee , Rowland, Kendrith M. , Song, Wei , Mulcahy, Mary F. , Whitehead, Robert P. , Petrelli, Nicholas J. , O’Dwyer, Peter J , Cella, David , Benson, Al B. , Catalano, Paul J , Cella, David , Benson, Al , Kam, Audrey E , Zhao, Fengmin , Sinicrope, Frank A. , Mayer, Robert J. , O’Dwyer, Peter J. , Hamilton, Stanley R.

Mayo Clinic

The Oncologist | December 13, 2025 | Volume: 31 | Issue: 1 | Pages: No page available

10.1093/oncolo/oyaf416 | PMID 41397917 Get It

Abstract Background Adjuvant 5-FU monotherapy was previously the standard treatment for stage II/III rectal cancer. This study compared adjuvant FOLFIRI, FOLFOX, and 5-FU/LV. Methods Eligible patients had T3-T4 N0 or Tany N1-3 rectal adenocarcinoma ≤12 cm from the anal verge and received pre-operative or postoperative 5-FU chemoradiotherapy (CRT). Patients were randomized to adjuvant FOLFIRI (8 cycles), FOLFOX (8 cycles), or 5-FU/LV weekly (6/8 weeks; 3 cycles). The trial planned to enroll 3,150 patients but was closed early following activation of an alternative adjuvant rectal cancer study including bevacizumab (E5204). The primary endpoint was overall survival (OS); secondary endpoints included disease-free survival (DFS), sphincter preservation, tolerability, and quality of life (QOL). Results The trial enrolled 225 patients (179 randomized) before early closure. Grade 3/4 toxicity occurred in 59%, with neutropenia, leukopenia, and diarrhea being the most common. At a median follow-up of 9.7 years, no significant OS or DFS differences were observed. The rate of sphincter preservation was numerically higher with FOLFIRI and FOLFOX versus 5-FU/LV, but the difference was not statistically significant. Conclusion FOLFOX and FOLFIRI can be safely administered after CRT in rectal cancer patients safely with expected toxicities. Due to early trial closure and small sample size, the survival analysis was underpowered to detect a significant difference between regimens. ClinicalTrials.gov identifier NCT00068692
In Memoriam Peter James Dyck, MD
Litchy, William J. , Dyck, Peter James

Mayo Clinic

Muscle & Nerve | December 13, 2025 | Volume: 73 | Issue: 2 | Pages: 125-127

10.1002/mus.70103 Get It

Emerging Therapies in Autosomal Dominant Polycystic Kidney Disease
Chen, Christopher Y. , Hadla, Mohamad , Khambati, Ibrahim, Kashyap, Sonu , Westerfield, Vanessa , Fedeles, Sorin , Besse, Whitney , Hopp, Katharina , Harris, Peter C. , Patel, Vishal , Chini, Eduardo N. , Salih, Mahdi , Chini, Eduardo, Barry, Michael A , Chebib, Fouad T , Harris, Peter C , Hadla, Mohamad , Fedeles, Sorin V. , Patel, Vishal , Khambati, Ibrahim, Westerfield, Vanessa , Barry, Michael A. , Chebib, Fouad T.

Mayo Clinic

Kidney360 | December 12, 2025 | Volume: 7 | Issue: 7 | Pages: 1662-1676

10.34067/kid.0000001109 | PMID 41385299 Get It

Autosomal dominant polycystic kidney disease is the most common inherited kidney disorder and a leading monogenic cause of kidney failure. Reduction or loss of polycystin-1 and polycystin-2 function disrupts ciliary calcium signaling, elevates cyclic AMP (cAMP), reprograms cellular metabolism, and activates proliferative cascades that drive cyst expansion. Tolvaptan, a vasopressin V2 receptor antagonist, established cAMP modulation as a disease-modifying strategy but is limited by aquaretic effects and hepatotoxicity risk. This review highlights emerging therapeutic strategies in clinical trial development that extend beyond vasopressin antagonism. Gene-directed therapies aim to restore polycystin dosage, including anti–miR-17 oligonucleotides ( e.g ., farabursen) and pharmacochaperones that rescue misfolded polycystin-1 and restore trafficking in select PKD1 missense variants ( e.g ., VX-407). Paracrine signaling can be modulated with anti–pregnancy-associated plasma protein A antibodies that reduce insulin-like growth factor-1 bioavailability in cystic microenvironments. Metabolic reprogramming is targeted by agents such as metformin, bempedoic acid, glucagon-like peptide-1 receptor agonists, and structured dietary interventions. Sodium-glucose cotransporter 2 inhibitors hold theoretical promise but await definitive results from ongoing trials. A novel cAMP-lowering strategy through phosphodiesterase-4 activation is advancing toward clinical testing. Looking ahead, gene therapy, and genome editing offer the potential to raise polycystin levels above the threshold for cystogenesis, although challenges in vector capacity, kidney-specific delivery, and durability remain. Artificial intelligence–guided discovery, coupled with human organoid platforms, is accelerating therapeutic repurposing and rational combination design. Collectively, these advances signal a transition toward a layered, mechanism-guided framework in which vasopressin blockade is integrated with metabolic, other signaling, and genotype-specific therapies. As biomarkers and risk stratification tools mature, autosomal dominant polycystic kidney disease management is poised to become increasingly precise, tolerable, and effective.
Benefit of rituximab maintenance after first-line bendamustine-rituximab in patients with mantle cell lymphoma
Wang, Yucai , Hwang, Steven R. , Villa, Diego , Kugathasan, Laveniya , Kumar, Anita , Joseph, Ashlee , Brooks, Taylor , Hill, Brian T. , Bond, David A. , Maddocks, Kami J. , Nizamuddin, Imran , Danilov, Alexey V. , Argao, Christine, Ruan, Jia , Khan, Nazneen B., Ouchveridze, Evguenia, Mou, Eric , Pongas, Georgios , Lossos, Izidore S. , Harris, Zoey I., Young, Philip, Greenwell, Irl Brian , Gerber, Drew G. , Wang, Michael , Narkhede, Mayur , Stack, Anthony , Messmer, Marcus , Moyo, Tamara K. , Anna, Jacob, Stanisic, Alexander , Cohen, Jonathon B. , Hwang, Steven R , Villa, Diego , Kumar, Anita , Joseph, Ashlee , Brooks, Taylor R , Bond, David A , Kahl, Brad S , Ryan, Christine E , Grover, Natalie S , Tun, Aung M , Mou, Eric , Lossos, Izidore S , Moustafa, Muhamad Alhaj , Pophali, Priyanka , Gerber, Drew , Jain, Preetesh , Wang, Michael L , Narkhede, Mayur S , Mehta, Amitkumar , Stack, Anthony C , Bhansali, Rahul S , Barta, Stefan K , Ghosh, Nilanjan , Kamdar, Manali , Stanisic, Alexander V , Karmali, Reem , Maurer, Matthew , Cerhan, James R , Cohen, Jonathon B , Wang, Yucai , Larson, Melissa C. , Kahl, Brad S. , Ryan, Christine E. , Merryman, Reid W. , Grover, Natalie S. , Ouchveridze, Evguenia, Tun, Aung M. , Ayyappan, Sabarish Ram , Muñoz, Javier , Portell, Craig A. , Baidoun, Firas , Moustafa, Muhamad Alhaj , Reagan, Patrick Michael , Banaszak, Lauren Gabriele , Pophali, Priyanka A. , Velayati, Arash , Jain, Preetesh , Mehta, Amitkumar , Bhansali, Rahul S. , Kamdar, Manali , Anna, Jacob, Karmali, Reem , Maurer, Matthew J. , Cerhan, James R. , Martin, Peter

Mayo Clinic

Blood Advances | December 11, 2025 | Volume: 10 | Issue: 4 | Pages: 1372-1380

10.1182/bloodadvances.2025018527 | PMID 41380101 Get It

Abstract The benefit of rituximab maintenance after first-line (1L) bendamustine-rituximab (BR) in patients with mantle cell lymphoma (MCL) remains uncertain, with inconsistent results from the phase 2 MAINTAIN trial and several retrospective studies. We conducted a large retrospective study at 27 US and Canadian academic centers to examine the benefit of rituximab maintenance after BR. A total of 911 patients received 1L BR between 2010 and 2020, and 703 had an objective response and no evidence of disease progression at the 3-month post-BR landmark. Among those, 394 (56%) received rituximab maintenance and 309 (44%) did not, with largely similar baseline patient and disease characteristics. In the landmark analysis, rituximab maintenance was associated with improved event-free survival (EFS; median, 49.9 vs 29.7 months; P< .001) as well as overall survival (OS; median, 109.5 vs 74.2 months; P< .001). The EFS and OS benefits were observed across most of the subgroups. EFS and OS differences were statistically significant in those who achieved a complete response to 1L BR (n = 590; median EFS, 62.7 vs 31.1 months [P< .001]; median OS, 136.1 vs 75.3 months [P< .001]), but the analysis among those who achieved a partial response to 1L BR was limited by the small sample size. These results provide additional evidence for the survival benefit of rituximab maintenance after BR in MCL and support its use in clinical trial design and routine practice.
Topical steroid withdrawal syndrome: developing diagnostic criteria through a modified Delphi method
Hsu, Cynhia, Guo, Lily, Adams, D. Daryl, Eichenfield, Lawrence F. , Friedman, Olivia Hsu, Serrao, Rocco, Sheary, Belinda , Sidbury, Robert , Yu, JiaDe , Davis, Dawn, Davis, Dawn Marie R. , Friedman, Olivia Hsu, Harris, Sarah, Shi, Vivian Y. , Simpson, Eric Lawrence , Lio, Peter

Mayo Clinic

British Journal of Dermatology | December 11, 2025 | Volume: 194 | Issue: 4 | Pages: 768-778

10.1093/bjd/ljaf518 | PMID 41379834 Get It

Abstract Background Topical steroid withdrawal syndrome (TSW) is an adverse event following discontinuation of topical corticosteroids (TCS) and is of growing interest among patients and dermatologists. The absence of well-defined diagnostic criteria and limited insights into the pathomechanisms make diagnosis and future research challenging. Objectives To propose preliminary diagnostic criteria for TSW with the erythemato-oedematous subtype applicable for adult and paediatric populations using a Delphi consensus approach informed by a thorough literature review that summarizes the signs, symptoms and histology of TSW. Methods Eleven clinicians experienced in diagnosing and treating suspected TSW in both children and adults participated in a three-round modified Delphi process. Two rounds of surveys were conducted, with items ranked using a 5-point Likert scale. A predefined consensus threshold of ≥ 75% was established for any one feature to be deemed important. The third round involved a live video conference where the panel reached a consensus on essential diagnostic criteria. Results The panel identified 18 critical diagnostic items, encompassing elements from the patient’s clinical history, signs and symptoms. This includes history of escalating TCS requirement, morphology and distribution differing from primary condition, regional or generalized spontaneous neuropathic pain and severe burning sensation of the skin. Conclusions Differentiating TSW from conditions such as severe atopic dermatitis remains challenging. By emphasizing the common signs and symptoms of TSW, we aim to encourage discussions among healthcare professionals and progress towards the development of a reliable diagnostic tool. An author video to accompany this article is available online.
Age modifies the association between sex and the plasma inflammatory proteome in treated HIV
Schnittman, Samuel R , Murad, Natália Faraj , Olshen, Adam B. , Beck‐Engeser, Gabriele, Aquino, Noah, Ambayec, Gabrielle C., Cachay, Edward R. , Eron, Joseph J. , Saag, Michael S, Nance, Robin M. , Delaney, Joseph A. , Moore, Richard D. , Jacobson, Jeffrey M. , Crane, Heidi M. , Hunt, Peter W. , Delaney, Joseph A C , Abelman, Rebecca A. , Aquino, Noah, Saag, Michael S. , Ruderman, Stephanie A. , Mayer, Kenneth Hugh

Mayo Clinic

Journal of Clinical Investigation | December 9, 2025 | Volume: 136 | Issue: 3 | Pages: No page available

10.1172/jci196869 | PMID 41364552 Get It

BACKGROUND Among antiretroviral therapy–suppressed (ART-suppressed) people with HIV (PWH), women have higher levels of some inflammatory markers than men, but the effect of sex on the inflammatory proteome, and whether age modifies these differences, remain unclear. METHODS Plasma inflammatory protein levels were assessed in ART-suppressed PWH from the Center for AIDS Research Network of Integrated Clinical Systems. The relationship between sex and plasma proteins — including 22 interferon-α response pathway proteins — was assessed, adjusting for confounders and assessing interactions by age. RESULTS Of 922 participants, 162 (18%) were female. The median age was 47, above which the majority of women had undetectable plasma anti-Müllerian hormone levels, a biomarker of ovarian reserve. Age modified the influence of sex on the inflammatory proteome. Older age (>47) was associated with greater increases among women than men in 194 proteins. Interferon-α response proteins were higher in men in those ≤ 47 but higher in women in those > 47 (interaction P < 0.001). Among the 131 proteins associated with mortality risk ( q < 0.05), only 5 differed by sex among those ≤ 47, while 79 differed by sex in those > 47, with nearly all being higher in women. Women had decreased mortality than men ≤ 47 ( P < 0.001) but had similar mortality > 47 ( P = 0.84). CONCLUSION The menopausal transition appears to increase systemic type I interferon responses and inflammation in women with HIV, which may contribute to a loss of female advantage in mortality. FUNDING NIH National Heart, Lung, and Blood Institute; National Institute of Neurological Disorders and Stroke; National Institute of Allergy and Infectious Diseases.
Imprinted Binary Colloidal Crystals Support Growth and Stemness of Mouse Embryonic Stem Cells
Babaie, Ali , Wang, Peng‐Yuan , Abedi, Ali , Uddin, Md Hemayet , Joseph, Shanthi, Sümer, Hüseyin , Uddin, Hemayet , Thissen, Helmut , Kingshott, Peter , Abedi, Ali

Mayo Clinic

ACS Biomaterials Science & Engineering | December 8, 2025 | Volume: 12 | Issue: 4 | Pages: 2156-2172

10.1021/acsbiomaterials.5c01187 | PMID 41358614 Get It

Association of SULT2A1 Locus With Abiraterone Clearance in the Alliance A031201 : Randomized Phase
Norton, Nadine , Larson, Nicholas B. , Jenkins, Gregory D. , Langevin, Brooke , Gobburu, Jogarao , Morris, Michael J. , Kroetz, Deanna L. , Zhu, Hao‐Jie , O’Donnell, Peter H. , Hertz, Daniel L. , Beumer, Jan Hendrik , Gobbaru, Jogarao , Morris, Michael J , Kroetz, Deanna L , Zhu, Hao-Jie , Lewis, Lionel D , Hertz, Daniel L , Larson, Nicholas B , Norton, Nadine , Nakamura, Yusuke , Lewis, Lionel D.

Mayo Clinic

Clinical and Translational Science | December 5, 2025 | Volume: 18 | Issue: 12 | Pages: No page available

10.1111/cts.70425 | PMID 41346252 Get It

ABSTRACT Enzalutamide and abiraterone are hormonal treatments that improve survival in metastatic castration‐resistant prostate cancer. Identifying genetic variants associated with the clearance of these drugs may aid in improved dosing and outcomes. We performed genetic association studies of enzalutamide and abiraterone oral clearance in the Alliance A031201 clinical trial. Genome‐wide genotyping was performed with the primary analysis limited to European‐descent participants. Pharmacogene metabolic phenotypes were estimated using PyPGx and Stargazer. Associations of metabolic activity groups for CYP3A4 , CYP3A5 , CYP2C19 and SLCO1B1 with enzalutamide clearance ( N = 706) and CYP3A4 , SLCO2B1 and UGT1A4 with abiraterone clearance ( N = 323) were tested by linear regression. Targeted SNP associations were assessed for abiraterone clearance at loci proximal to major metabolizing genes. Full genome‐wide association studies were performed for both sets of clearance values. No significant associations were identified between metabolic phenotypes and enzalutamide or abiraterone oral clearance SNPs in the SULT2A1 5′ flanking region were significantly associated with lower abiraterone clearance, (rs296373, minor allele frequency = 0.15, β = −0.457, p = 3.2E‐06). Liver protein and liver and adrenal gland gene expression QTL databases indicated significantly lower SULT2A1 expression patterns for individuals carrying associated alleles, likely explaining the lower abiraterone oral clearance. CYP2C8*3 was associated with higher enzalutamide clearance ( p = 0.012), but this was not significant after correction for multiple testing. This study is the first to identify the genetic association of SULT2A1, known to be involved in the metabolism of steroids in the liver and adrenal glands, with abiraterone clearance. Genetic variation in SULT2A1 may be useful to inform personalized dosing of abiraterone. ClinicalTrials.gov Identifier: NCT01949337
Identifying candidates for outpatient administration of ciltacabtagene autoleucel (Cilta-cel) in relapsed-refractory multiple myeloma (RRMM)
Peres, Lauren C. , Shune, Leyla , Leitzinger, Christelle, Reid, Brett M. , Cassano, Raffaella Cassano , Kalariya, Nilesh, Gaballa, Mahmoud , Hunzeker, Zachary , Hosoya, Hitomi , Mikkilineni, Lekha , Gonzalez, Rebecca , Cahoon, Christopher, Sborov, Douglas W. , Bhurtel, Jenny , Purvey, Sneha , Ferreri, Christopher J. , Varga, Cindy , Voorhees, Peter M. , Goel, Utkarsh, Khouri, Jack , Afrough, Aimaz , Sannareddy, Aishwarya , Hassan, Hamza , Gordillo, Christian , Biran, Noa , Green, Kimberly , Zanwar, Saurabh , Costa, Luciano da Fontoura , Bal, Susan , Midha, Shonali , Alsina, Melissa , Shain, Kenneth H. , Kumar, Shaji , Patel, Krina, Sidana, Surbhi , Hansen, Doris, Davis, James A. , Sidana, Surbhi , Davis, James A , Hosoya, Hitomi , Dima, Danai , Colin, Christelle , Portuguese, Andrew J. , Banerjee, Rahul , Pasvolsky, Oren , Dillard, Christen , Grajales‐Cruz, Ariel , Puglianini, Omar Castañeda , Nishihori, Taiga , Wagner, Charlotte B , Kort, Jeries , Geer, Marcus , Atrash, Shebli , Goel, Utkarsh , Raza, Shahzad , Anwer, Faiz , Anderson, Larry D. , Herr, Megan M. , Reshef, Ran , Zolotov, Eli , Biran, Noa , Davis, James, Green, Kimberly, Lin, Yi , Costa, Luciano, Nadeem, Omar , Baz, Rachid , Locke, Frederick L. , Patel, Krina K. , Hansen, Doris K.

Mayo Clinic

Blood | December 5, 2025 | Volume: 146 | Issue: Supplement 1 | Pages: 4000-4000

10.1182/blood-2025-4000 Get It

Abstract Introduction: Cilta-cel is a BCMA-directed CAR T-cell therapy that has shown remarkable efficacy in patients with RRMM. As real-world (RW) experience with cilta-cel continues to expand, and with the recent FDA guidance reducing the recommended proximity to the CAR T center from four to two weeks post-infusion, there is growing interest in identifying patients at low risk for severe early complications who may be safely managed in the outpatient setting and potentially ‘discharged’ home earlier. Methods Data were collected from 769 patients with RRMM treated with cilta-cel at 15 institutions in the U.S. via the Multiple Myeloma Immunotherapy Consortium.Logistic regression was used to identify predictors of patients who could be managed in the outpatient setting (low-risk group). Based on expert consensus within the Consortium, low-risk patients were defined as: grade ≤1 CRS, no ICANS, and no IEC-HS. The remaining patients were categorized as high-risk. We evaluated baseline characteristics with missingness &lt; 20% as predictors, including age, sex, race, and ethnicity, ECOG performance status (PS) at time of lymphodepletion (LD), extramedullary disease, bone marrow plasma cell (BMPC) percentage, high-risk cytogenetics, bridging therapy including response, penta-refractory status, number of prior lines of therapy, prior anti-BCMA therapy, baseline C-reactive protein (CRP), and baseline ferritin. The cohort was restricted to patients with complete data on all predictors (n=455) and split into a training and testing cohort (80/20 split, n=364/91). Bidirectional stepwise regression was used to build the predictive model using variables with significance of p&lt;0.15 selected for entry. The best model was selected based on the AIC (Akaike Information Criterion) and a significance level of p&lt;0.05. Results Among the 455 patients with complete data included in the final model, 290 (64%) were categorized as low-risk and 165 (36%) as high-risk. Compared to the low-risk group, high-risk patients were more likely to have an ECOG PS ≥2 at time of LD (20% vs 9%, p&lt;0.001), high-risk cytogenetics (47% vs 35%, p=0.009), and penta-refractory disease status (34% vs 24%, p=0.031). High-risk patients also had a higher median BMPC percentage (15% vs 5%, p&lt;0.001), and higher baseline pre-LD CRP and ferritin. Overall response rates were high, at 95% vs 90% (p=0.047) for the low vs high risk groups, with complete response or better achieved in 73% vs 66% of patients, respectively (p=0.14). With a median follow-up of approximately 11 months, median progression-free survival was not reached (95% CI: 27-NA) in the low-risk group and 18.2 months (95% CI: 13.1-NA) in the high-risk group. In terms of safety, non-ICANS neurotoxicity (NINT) occurred less frequently in the low-risk group (6.6% vs 13%, p=0.015). Specifically, Parkinsonism was observed in 1.7% vs 6.1% (p=0.013), and cranial nerve palsy in 4.5% vs 5.5% (p=0.7), respectively. Non-relapse mortality (NRM) was lower in the low-risk group (4.2%) compared to the high-risk group (14%; p &lt; 0.001). The most common causes of NRM in the low- and high-risk groups were acute toxicities (0% vs 36%, including CRS, IEC-HS, and ICANS), delayed toxicities (0% vs 8%, including colitis, NINT, and Parkinsonism), infections (50% vs 48%), and other unrelated causes (50% vs 8%). The best model to predict low-risk patients that could be managed in the outpatient settingincluded BMPC percentage and ECOG PS at LD. In the training cohort, patients with a higher pre-LD BMPC percentage and an ECOG PS ³2 were less likely to be in the low-risk group(OR per 1-unit change in BMPC percentage = 0.99, 95% CI=0.98-0.99, p&lt;0.001 and OR for ECOG PS 2-4 = 0.38, 95% CI=0.20-0.72, p=0.003). The AUC for this model was 0.663 in the training cohort and 0.659 in the testing cohort. Conclusion In this large, multi-institutional cohort of patients with RRMM treated with cilta-cel, we identified clinical factors associated with lower risk for early severe toxicities, supporting outpatient administration and the potential for earlier discharge in selected patients, particularly those who are fit and have low disease burden. Our findings provide a practical framework to guide risk stratification and outpatient CAR T management strategies, particularly in light of evolving regulatory guidance and growing RW experience with cilta-cel.
Mortality in immune TTP remains unpredictable: Shortcomings of prediction models despite machine learning advances
Kashinath, Sanjana Kalvehalli , Singal, Mukul , Singh, Rishabh , Bechara, Simon, Peterson, Cecilia, Lee, Ho Jun , Mitchell, Carley , Nayak, Lalitha , Investigators, USTMA, Singal, Mukul , Singh, Rishabh , Abou-Ismail, Mouhamed Yazan , Sridharan, Meera , Khouri, Ashley , Kandula, Manasa , Zhang, Chong , Kouides, Peter A. , Mazepa, Marshall , Lim, Ming

Mayo Clinic

Blood | December 5, 2025 | Volume: 146 | Issue: Supplement 1 | Pages: 3105-3105

10.1182/blood-2025-3105 Get It

Abstract Background Despite advances in the diagnosis and treatment of immune thrombotic thrombocytopenic purpura (iTTP), recent mortality estimates remain around 5–10%. Predicting iTTP mortality risk has been of interest, as it may help individualize treatment or potentially guide the use of more intensive or novel therapies based on disease severity. However, prior attempts at mortality prediction have yielded inconsistent results, and no individual variable has demonstrated independent or reliable predictive ability. In a previous analysis utilizing the USTMA iTTP registry, which included 419 patients from 15 TTP referral centers, we reported that mortality due to immune TTP was unpredictable (Blood. 2021;138[Suppl 1]:1047). Neither the French Thrombotic Microangiopathy (TMA) Reference Score (previously validated in the French TMA Registry), nor a previous logistic regression model attempt (developed by USTMA investigators in 2021) demonstrated sufficient accuracy in predicting iTTP mortality in the USTMA dataset (AUC = 0.63 and 0.69, respectively). We subsequently utilized gradient boosted machine, a machine learning approach capable of handling multiple continuous variables and the complex interactions between them in large datasets, and developed a novel prediction tool: the USTMA Mortality Index (Res Pract Thromb Haemost. 2024; 8(3):102388). It demonstrated good performance in predicting iTTP mortality (AUC = 0.77) in repeated 10-fold cross-validation. However, it has not yet undergone external validation. Objectives To externally validate the USTMA Mortality Index to predict mortality due to acute iTTP in a multicenter cohort. Methods We performed an external validation using an independent cohort of iTTP patients from 5 institutions: University of Utah, Case Western Reserve University, Rochester Regional Health, University of Illinois, and Mayo Clinic. Patients in the validation cohort were not part of the development cohort (the USTMA registry). We included patients with confirmed iTTP and defined acute iTTP mortality as death within 30 days of admission. USTMA Mortality Index variables were collected at initial presentation, which included (in order of highest to lowest relative influence): lactate dehydrogenase, serum creatinine, age, hemoglobin, platelet count, presence of stupor/coma, fever. The model's prediction accuracy was assessed using area under the receiver operating characteristic curve (AUC). We calculated sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) based on the previously defined cut-offs of 4.27% and 9.08% mortality risk in the original model, which categorized patients into standard risk, high risk, and very high risk of predicted mortality. Results The external validation cohort included 103 patients with confirmed iTTP and 11 deaths (10.7% mortality rate). The USTMA Mortality Index demonstrated poor performance with AUC of 0.69 (95% CI, 0.55–0.83) in the validation cohort. The wide confidence interval reflects substantial uncertainty in model performance, ranging from poor to excellent, and is likely due to the small number of deaths. At a risk threshold ≥4.27%:Sensitivity = 64%Specificity = 70%PPV = 20%NPV = 94% At a risk threshold ≥9.08%:Sensitivity = 18%Specificity = 87%PPV = 14%NPV = 90% Conclusion The USTMA Mortality Index demonstrated poor performance in the external validation cohort (AUC = 0.69, 95% CI, 0.55–0.83), contrasting with its previously favorable performance in repeated 10-fold cross-validation. This discrepancy likely reflects model overfitting, a known challenge in AI-based clinical modeling. Our study is limited by the small number of deaths, resulting in a wide confidence interval ranging from poor to excellent performance. Given that neither the French TMA Reference Score, nor our group's prior logistic regression model (2021), nor the USTMA Mortality Index (2024) could reliably predict mortality upon external validation in our cohorts, these findings collectively suggest that mortality in acute iTTP remains difficult to predict at this time, regardless of statistical methodology or current machine learning capabilities. Clinical decision-making, including the use of therapies such as caplacizumab, should not be guided solely by mortality risk predictions. Instead, efforts to reduce mortality and improve outcomes should prioritize individualized clinical assessment over model-based stratification at this time.