Ronac Mamtani
· MD, MSCEVerifiedUniversity of Pennsylvania · Rehabilitation Medicine
Active 1988–2026
About
Ronac Mamtani, MD, MSCE, is an Associate Professor in GU Oncology at the University of Pennsylvania's Perelman School of Medicine. He serves as an Attending Physician in Hematology-Oncology at the Hospital of the University of Pennsylvania and is the Section Chief of GU Medical Oncology. His educational background includes a BS from Cornell University, an MD in Internal Medicine from Stony Brook School of Medicine, and an MS in Clinical Epidemiology from the University of Pennsylvania. His research and clinical interests focus on genitourinary cancers, with notable contributions to understanding racial disparities in targeted therapies for metastatic breast cancer, the application of artificial intelligence in patient-clinician communication, and the monitoring of tumor-derived DNA in bladder cancer. Dr. Mamtani is actively involved in advancing cancer research, particularly in the areas of oncology AI, targeted therapy options, and bladder-sparing approaches, contributing to the scientific community through various publications and presentations.
Research topics
- Internal medicine
- Medicine
- Immunology
- Oncology
- Urology
Selected publications
Journal of Cancer Policy · 2026-04-21
articleOpen accessSenior authorBACKGROUND: Artificial intelligence (AI) and machine learning (ML) tools are increasingly embedded in cancer care, yet the scope of U.S. Food and Drug Administration (FDA) oncology-specific authorizations and the clinical evidence described in publicly available decision documentation remain unclear. METHODS: We conducted a cross-sectional analysis of FDA-authorized AI/ML-enabled devices with oncology-specific indications from January 12, 2021, to September 12, 2025. Devices were identified from the FDA AI-Enabled Medical Device List and linked to FDA decision documents. Using a prespecified coding manual, we abstracted cancer type, clinical domain, whether indications were screening-, diagnosis-, and/or treatment-related, how devices fit into the FDA's computer-aided detection, diagnosis, and triage (CAD) taxonomy, and evidence features: (1) clinical testing using patient-derived data, (2) clinician-in-the-loop testing (studies assessing clinician performance with device output), and (3) prospective testing. RESULTS: Of 1008 FDA-authorized AI/ML devices, 149 (15%) had oncology-specific indications. Indications clustered in radiology (69/149, 46%) and radiation oncology (57/149, 38%). Of the 149 devices, 113 (76%) reported clinical testing, 31 (21%) clinician-in-the-loop testing, and 7 (5%) prospective testing. Higher-tier evidence (clinician-in-the-loop and/or prospective testing) was significantly more common among CAD devices (20/43, 47%) than non-CAD devices (11/106, 10%; p < 0.001). CONCLUSIONS: Oncology AI/ML device authorizations are concentrated in imaging and radiation oncology domains, with publicly described clinician-in-the-loop and prospective evaluations remaining uncommon overall, though higher-tier evidence was more frequent among CAD devices designed to directly aid clinician interpretation. Evidentiary expectations should be calibrated to device function and clinical risk, with stronger evaluation requirements for devices that directly shape decision-making.
JNCI Cancer Spectrum · 2026-04-21
articleOpen accessPURPOSE: We aimed to determine temporal trends and racial disparities in utilization and time to treatment initiation (TTI) of CDK4/6 inhibitors (CDK4/6i) and pertuzumab for first-line metastatic breast cancer (MBC). DESIGN: We extracted data from a nationwide electronic health record-derived deidentified database. Female patients ≥18 years old with ER+/HER2- or HER2+ MBC eligible for CDK4/6i(3/2015-10/2021) or pertuzumab(07/2012-09/2021) were included. Our outcomes were adjusted temporal trends in the proportion of patients receiving respective therapies using logistic regression with natural cubic splines for time trends and tested for changes in utilization over time within and between racial groups (non-Hispanic White (NHW) or non-Hispanic Black (NHB). Similar models using linear regression estimated mean TTI. RESULTS: 5173(NHW = 4478; NHB = 695) ER+/HER2- and 2321(NHW = 1915; NHB = 406) HER2+ MBC patients were included. There were significant differences in the proportion initiating CDK4/6i over time within racial groups (NHW, 23.5%(95%CI: 20.1%-27.3%) in 2015 to 53.8%(95%CI: 48.6%-59.0%) in 2021; NHB, 20.6%(95%CI: 11.9%-33.0%) in 2015 to 73.6%(95%CI: 61.7%-83.0%) in 2021) and between groups(p = 0.009). There was a significant increase in utilization of pertuzumab within both racial groups over time(p < 0.001), but no significant difference between groups(p = 0.45). TTI decreased over time with no significant differences in TTI trends between the two groups. CONCLUSIONS: Utilization of targeted therapies increased over time, however NHB patients were less likely to receive CDK4/6i compared to NHW. Approximately half of eligible patients did not receive pertuzumab. Further research is needed to understand mediators and design interventions to address underutilization of these therapies and those contributing to racial disparities in CDK4/6i utilization.
Missingness in Eligibility Criteria for Target Trial Emulation in EHR With Survival Outcomes
Statistics in Medicine · 2026-04-01
articleOpen accessIn certain settings, when conducting a randomized trial would be infeasible, electronic health records (EHR) can be used to emulate a target trial and estimate causal effects of an intervention. This process involves specifying the elements of a hypothetical trial protocol and applying these to the design of an observational study conducted with EHR data (or other observational data source). One element of target trial specification includes defining eligibility criteria. However, defining the eligible population with EHR can be complicated by missingness in eligibility-defining variables. Multiple imputation (MI) is one common approach to missingness in EHR data, but it is unclear whether imputation of eligibility criteria should occur before or after excluding ineligible individuals. Motivated by a target trial emulation of two treatments for advanced breast cancer, we explore this question when estimating the average causal effect under a target trial framework with survival outcomes. We illustrate how alternative MI strategies perform using simulated data and in a real-world analysis of oncology EHR data. We found that in most settings with high proportions of missingness in eligibility-defining variables, imputing missing data using a flexible imputation model, such as a random forest, prior to excluding ineligible individuals resulted in lower bias than complete case analysis or imputation after excluding ineligible individuals. Choices about how to handle practical challenges such as this in the application of target trial emulation to messy, real-world data sources can have substantial effects on causal parameter estimation and should be carefully considered to ensure that the results of observational studies are as rigorous as possible.
The Journal of Urology · 2026-04-27
articleUrologic Oncology Seminars and Original Investigations · 2025-08-05 · 3 citations
articleOpen accessSenior authorBACKGROUND: The combination of enfortumab vedotin (EV) and pembrolizumab (EV+P) was recently approved as a first-line (1L) therapy for patients with advanced urothelial cancer (aUC). Preclinical studies have suggested that these 2 drugs synergize with one another to drive anti-tumor responses. However, it remains unknown whether EV and pembrolizumab demonstrate synergistic activity in a clinical setting. METHODS: We analyzed progression-free survival (PFS) from the pivotal clinical trials evaluating EV and/or pembrolizumab as 1L therapy for aUC, focusing on cisplatin-ineligible patients. We computed predicted PFS for combination EV+P under a statistical model of independent drug action. We then compared predicted PFS to observed PFS to ascertain whether EV+P demonstrates synergistic vs. independent drug activity. RESULTS: Predicted PFS for EV+P combination therapy, assuming independent action of EV and pembrolizumab, was clinically and statistically indistinguishable from observed PFS for EV+P in the EV-302 trial (HR = 1.04 [0.79-1.37], P = 0.76). CONCLUSIONS: Among cisplatin-ineligible patients with untreated aUC, the observed clinical efficacy of combination EV+P is supported by a model of independent drug action. These findings suggest that distinct patient subgroups respond to EV and/or pembrolizumab. Identifying predictive biomarkers of response for each drug could reduce unnecessary toxicity arising from universal combination therapy, as patients could instead be selectively treated with whichever therapy is more likely to be effective.
Annals of Oncology · 2025-09-01
articleUrologic Oncology Seminars and Original Investigations · 2025-11-17 · 1 citations
articleOpen accessBACKGROUND AND OBJECTIVE: Enfortumab vedotin plus pembrolizumab (EV+P) is now the standard first-line (1L) therapy for advanced urothelial cancer (aUC), based on improved survival in the EV-302 trial. However, the trial excluded patients with creatinine clearance (CrCl) <30 ml/min, leaving an evidence gap for patients with severely impaired renal function. To address this, we evaluated outcomes of EV+P in patients with aUC and CrCl <30 ml/min using real-world data. METHODS: We conducted a real-world retrospective cohort study using a database derived from electronic health records from approximately 280 U.S. oncology practices. Adults with aUC initiating 1L EV+P between April 2023 and December 2024 were included. Outcomes included overall survival (OS), progression-free survival (PFS), and EV interruption-free survival (IFS), stratified by baseline CrCl (≥30 vs. <30 ml/min). We constructed multivariable Cox models adjusted for demographics, clinical factors, and potential confounders. RESULTS: Among 462 eligible patients who initiated 1L EV+P between April 2023 and December 2024, 65 (14.1%) had CrCl <30 ml/min. In multivariable Cox models, severely impaired renal function was not associated with worse overall survival (OS) (adjusted HR [aHR] = 0.95, 95% CI [0.61-1.49]; P = 0.84), progression-free survival (PFS) (aHR = 0.70 [0.47-1.06]; P = 0.092), or EV interruption-free survival (IFS) (aHR = 0.82 [0.48-1.38]; P = 0.45). CONCLUSIONS: These real-world findings indicate that patients with CrCl <30 ml/min experienced outcomes comparable to those with higher renal function, providing important evidence in a population that is often excluded from clinical trials.
Value in Health · 2025-07-01
articleSenior authorJournal of Managed Care & Specialty Pharmacy · 2025-09-17
articleSenior authorBACKGROUND: Bladder cancer is a common cancer with significant morbidity, mortality, and economic cost. Muscle-invasive bladder cancer (MIBC) is typically managed with radical cystectomy (RC). Despite its curative intent, a considerable proportion of patients experience recurrence after RC. The economic impact of recurrence among patients with surgically resected MIBC has not been described. OBJECTIVE: To assess health care resource utilization (HCRU) and costs among patients with surgically resected MIBC in the United States, including the impact of disease recurrence. METHODS: In this retrospective, observational study, the Surveillance, Epidemiology, and End Results-Medicare database (2007-2020) was used to identify patients diagnosed with T2-T4aN0M0 or T1-T4aN1M0 MIBC who underwent RC in the United States. Index date was the date of RC. Patients were stratified by whether they experienced recurrence following surgical resection. The index date for patients with recurrence was defined as 30 days prior to recurrence, and for patients without recurrence, the index date was drawn from a distribution to match the time window between surgical resection and the index date in the recurrence cohort. Patients were followed from the index date until the end of data availability, continuous enrollment, or death. Rates of HCRU per patient per year (PPPY) and mean health care costs per patient per month (PPPM; in 2022 USD) were summarized and compared between cohorts. RESULTS: < 0.001). CONCLUSIONS: Surgically resected MIBC was associated with a substantial economic burden with disease recurrence experiencing higher HCRU and health care costs. These findings underscore the need for novel and effective therapies that can prevent or delay disease recurrence for patients with MIBC.
Second-Line Treatment Strategies for Right-Sided, RAS/RAF Wild-Type Colorectal Cancer
JAMA Network Open · 2025-06-12
articleOpen accessThis comparative effectiveness study investigates anti–vascular endothelial growth factor vs anti–epidermal growth factor receptor therapy in second-line treatment among patients with RAS/RAF wild-type, right-sided cancer.
Recent grants
Insulin resistance in the development and progression of invasive bladder cancer
NIH · $872k · 2015–2020
Frequent coauthors
- 225 shared
Rick Bangs
SWOG Cancer Research Network
- 215 shared
Elizabeth R. Plimack
Fox Chase Cancer Center
- 214 shared
Kevin Chan
City Of Hope National Medical Center
- 214 shared
Philippe E. Spiess
Moffitt Cancer Center
- 212 shared
Thomas W. Flaig
University of Colorado Cancer Center
- 212 shared
Subodh M. Lele
Fred and Pamela Buffett Cancer Center
- 212 shared
Neeraj Agarwal
University of Utah
- 212 shared
Mark K. Buyyounouski
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