Phase 1 trial of navitoclax and sorafenib in patients with relapsed or refractory solid tumors with hepatocellular carcinoma expansion cohort.

Navitoclax (ABT-263) is an oral BCL2 homology-3 mimetic that binds with high affinity to pro-survival BCL2 proteins, resulting in apoptosis. Sorafenib, an oral multi kinase inhibitor also promotes apoptosis and inhibits tumor angiogenesis. The efficacy of either agent alone is limited; however, preclinical studies demonstrate synergy with the combination of navitoclax and sorafenib. In this phase 1 study, we evaluated the combination of navitoclax and sorafenib in a dose escalation cohort of patients with refractory solid tumors, with an expansion cohort in hepatocellular carcinoma (HCC). Maximum tolerated dose (MTD) was determined using the continual reassessment method. Navitoclax and sorafenib were administered continuously on days 1 through 21 of 21-day cycles. Ten patients were enrolled in the dose escalation cohort and 15 HCC patients were enrolled in the expansion cohort. Two dose levels were tested, and the MTD was navitoclax 150 mg daily plus sorafenib 400 mg twice daily. Among all patients, the most common grade 3 toxicity was thrombocytopenia (5 patients, 20%): there were no grade 4 or 5 toxicities. Patients received a median of 2 cycles (range 1-36 cycles) and all patients were off study treatment at data cut off. Six patients in the expansion cohort had stable disease, and there were no partial or complete responses. Drug-drug interaction between navitoclax and sorafenib was not observed. The combination of navitoclax and sorafenib did not increase induction of apoptosis compared with navitoclax alone. Navitoclax plus sorafenib is tolerable but showed limited efficacy in the HCC expansion cohort. These findings do not support further development of this combination for the treatment of advanced HCC. This phase I trial was conducted under ClinicalTrials.gov registry number NCT01364051.

Induction of antitumor cytotoxic lymphocytes using engineered human primary blood dendritic cells.

Dendritic cell (DC)-based cancer immunotherapy has achieved modest clinical benefits, but several technical hurdles in DC preparation, activation, and cancer/testis antigen (CTA) delivery limit its broad applications. Here, we report the development of immortalized and constitutively activated human primary blood dendritic cell lines (ihv-DCs). The ihv-DCs are a subset of CD11c+/CD205+ DCs that constitutively display costimulatory molecules. The ihv-DCs can be genetically modified to express human telomerase reverse transcriptase (hTERT) or the testis antigen MAGEA3 in generating CTA-specific cytotoxic T lymphocytes (CTLs). In an autologous setting, the HLA-A2+ ihv-DCs that present hTERT antigen prime autologous T cells to generate hTERT-specific CTLs, inducing cytolysis of hTERT-expressing target cells in an HLA-A2-restricted manner. Remarkably, ihv-DCs that carry two allogeneic HLA-DRB1 alleles are able to prime autologous T cells to proliferate robustly in generating HLA-A2-restricted, hTERT-specific CTLs. The ihv-DCs, which are engineered to express MAGEA3 and high levels of 4-1BBL and MICA, induce simultaneous production of both HLA-A2-restricted, MAGEA3-specific CTLs and NK cells from HLA-A2+ donor peripheral blood mononuclear cells. These cytotoxic lymphocytes suppress lung metastasis of A549/A2.1 lung cancer cells in NSG mice. Both CTLs and NK cells are found to infiltrate lung as well as lymphoid tissues, mimicking the in vivo trafficking patterns of cytotoxic lymphocytes. This approach should facilitate the development of cell-based immunotherapy for human lung cancer.

Calcium: magnesium intake ratio and colorectal carcinogenesis, results from the prostate, lung, colorectal, and ovarian cancer screening trial.

BACKGROUND: We aimed to evaluate the associations between calcium and various stages of colorectal carcinogenesis and whether these associations are modified by the calcium to magnesium (Ca:Mg) ratio. METHODS: We tested our hypotheses in the prostate lung, colorectal and ovarian cancer screening trial. RESULTS: Calcium intake did not show a dose-response association with incident adenoma of any size/stage (P-trend = 0.17), but followed an inverse trend when restricted to synchronous/advanced adenoma cases (P-trend = 0.05). This inverse trend was mainly in participants with Ca:Mg ratios between 1.7 and 2.5 (P-trend = 0.05). No significant associations were observed for metachronous adenoma. Calcium intake was inversely associated with CRC (P-trend = 0.03); the association was primarily present for distal CRC (P-trend = 0.01). The inverse association between calcium and distal CRC was further modified by the Ca:Mg ratio (P-interaction < 0.01); significant dose-response associations were found only in participants with a Ca:Mg ratio between 1.7 and 2.5 (P-trend = 0.04). No associations for calcium were found in the Ca:Mg ratio above 2.5 or below 1.7. CONCLUSION: Higher calcium intake may be related to reduced risks of incident advanced and/or synchronous adenoma and incident distal CRC among subjects with Ca:Mg intake ratios between 1.7 and 2.5.

VetLLM: Large Language Model for Predicting Diagnosis from Veterinary Notes.

Lack of diagnosis coding is a barrier to leveraging veterinary notes for medical and public health research. Previous work is limited to develop specialized rule-based or customized supervised learning models to predict diagnosis coding, which is tedious and not easily transferable. In this work, we show that open-source large language models (LLMs) pretrained on general corpus can achieve reasonable performance in a zero-shot setting. Alpaca-7B can achieve a zero-shot F1 of 0.538 on CSU test data and 0.389 on PP test data, two standard benchmarks for coding from veterinary notes. Furthermore, with appropriate fine-tuning, the performance of LLMs can be substantially boosted, exceeding those of strong state-of-the-art supervised models. VetLLM, which is fine-tuned on Alpaca-7B using just 5000 veterinary notes, can achieve a F1 of 0.747 on CSU test data and 0.637 on PP test data. It is of note that our fine-tuning is data-efficient: using 200 notes can outperform supervised models trained with more than 100,000 notes. The findings demonstrate the great potential of leveraging LLMs for language processing tasks in medicine, and we advocate this new paradigm for processing clinical text.

A phase I study of the ceramide nanoliposome in patients with advanced solid tumors.

PURPOSE: Ceramide is a sphingolipid metabolite that deactivates multiple oncogenic signaling pathways and promotes cell death. In-vivo data demonstrate single-agent anti-cancer activity and enhanced efficacy with combination strategies. This phase I dose-escalation trial evaluated Ceramide nanoLiposomes (CNL) in patients with advanced solid tumors and no standard treatment option. METHODS: The primary objective was to establish the maximum tolerated dose. Secondary objectives included determining the recommended phase II dose, the safety and tolerability, the pharmacokinetic profile and preliminary anti-tumor efficacy. RESULTS: 15 patients with heavily pretreated metastatic disease enrolled. Safety data were analyzed for all patients, while pharmacokinetic data were available for 14 patients. There were no grade 3 or higher treatment-related adverse events. The maximum tolerated dose was not reached and there were no dose-limiting toxicities. The most common grade 1 or 2 treatment-related adverse events included headache, fatigue, constipation, nausea and transaminitis. The maximum concentration and area under the curve increased with dose. Clearance was consistent between doses and was observed mainly through the liver without significant hepatotoxicity. The half-life ranged from 20 to 30 h and the volume of distribution was consistent with a lipophilic drug. CONCLUSIONS: CNL exhibited an encouraging safety profile and pharmacokinetic parameters, with some signals of efficacy including prolonged stable disease in 1 patient with refractory pancreatic cancer. Pre-clinical data indicate potential synergy between CNL and multiple systemic therapies including chemotherapy, targeted therapy, and immunotherapy. Future studies are planned investigating CNL in combination strategies. TRIAL REGISTRATION: This study is registered under ClinicalTrials.gov ID: NCT02834611.

DNAJB1-PRKACA fusion neoantigens elicit rare endogenous T cell responses that potentiate cell therapy for fibrolamellar carcinoma.

Fibrolamellar carcinoma (FLC) is a liver tumor with a high mortality burden and few treatment options. A promising therapeutic vulnerability in FLC is its driver mutation, a conserved DNAJB1-PRKACA gene fusion that could be an ideal target neoantigen for immunotherapy. In this study, we aim to define endogenous CD8 T cell responses to this fusion in FLC patients and evaluate fusion-specific T cell receptors (TCRs) for use in cellular immunotherapies. We observe that fusion-specific CD8 T cells are rare and that FLC patient TCR repertoires lack large clusters of related TCR sequences characteristic of potent antigen-specific responses, potentially explaining why endogenous immune responses are insufficient to clear FLC tumors. Nevertheless, we define two functional fusion-specific TCRs, one of which has strong anti-tumor activity in vivo. Together, our results provide insights into the fragmented nature of neoantigen-specific repertoires in humans and indicate routes for clinical development of successful immunotherapies for FLC.

Impact of genetic targets on cancer therapy in esophagogastric cancer.

The treatment of esophagogastric cancer has been rapidly evolving in the past decade. New cytotoxic drugs and targeted agents have been integrated in the therapeutic paradigm. To better understand the tumor biology and to better utilize targeted agents, genetic alterations in esophagogastric cancer have been actively explored. For example, Her2/Neu amplification and expression were observed in gastric and gastroesophageal (GE) junction cancers. Combination of trastuzumab with cytotoxic chemotherapy has demonstrated a survival advantage in patients with Her2/Neu positive gastric cancer. However, the prognosis of advanced esophagogastric cancer remains poor. This is largely attributed to the tumor heterogeneity and poorly understood tumor biology. This article provides a summary of potential genetic targets and the role of novel targeted agents in the treatment of esophagogastric cancer.

BRAF-Driven Pancreatic Cancer: Prevalence, Molecular Features, and Therapeutic Opportunities.

BRAF-altered pancreatic cancer is an important molecular subgroup that activates the mitogen-activated protein kinase pathway and promotes tumorigenesis. This manuscript reviews the prevalence and molecular features of BRAF-driven pancreatic cancer and also explores the published data about targeted approaches for this subgroup. A review of the existing literature was undertaken through the PubMed database using the search terms BRAF mutation, BRAF fusion, BRAF deletion, mitogen-activated protein kinase pathway, and pancreatic cancer. Pathogenic BRAF variants are enriched in KRAS wild-type (WT) tumors and drive tumorigenesis in in vitro and experimental animal models. The majority of clinical cases are comprised of V600E mutations, N486-P490 deletions and fusions. Anecdotal evidence is building that KRAS-WT, BRAF-driven pancreatic cancers are sensitive either to BRAF inhibitors, MEK inhibitors, or combination strategies. Precision medicine has transformed the treatment landscape for several cancers. With increasing knowledge about molecular drivers in pancreatic cancer, it is critical to characterize each distinct subgroup and evaluate targeted approaches to improve clinical outcomes.

Potential Immunotherapy Targets for Liver-Directed Therapies, and the Current Scope of Immunotherapeutics for Liver-Related Malignancies.

Liver cancer, including hepatocellular carcinoma and intrahepatic cholangiocarcinoma, is increasing in incidence and mortality across the globe. An improved understanding of the complex tumor microenvironment has opened many therapeutic doors and led to the development of novel pharmaceuticals targeting cellular signaling pathways or immune checkpoints. These interventions have significantly improved tumor control rates and patient outcomes, both in clinical trials and in real-world practice. Interventional radiologists play an important role in the multidisciplinary team given their expertise in minimally invasive locoregional therapy, as the bulk of these tumors are usually in the liver. The aim of this review is to highlight the immunological therapeutic targets for primary liver cancers, the available immune-based approaches, and the contributions that interventional radiology can provide in the care of these patients.

Probabilistic Prediction of Laboratory Test Information Yield.

Low-yield repetitive laboratory diagnostics burden patients and inflate cost of care. In this study, we assess whether stability in repeated laboratory diagnostic measurements is predictable with uncertainty estimates using electronic health record data available before the diagnostic is ordered. We use probabilistic regression to predict a distribution of plausible values, allowing use-time customization for various definitions of "stability" given dynamic ranges and clinical scenarios. After converting distributions into "stability" scores, the models achieve a sensitivity of 29% for white blood cells, 60% for hemoglobin, 100% for platelets, 54% for potassium, 99% for albumin and 35% for creatinine for predicting stability at 90% precision, suggesting those fractions of repetitive tests could be reduced with low risk of missing important changes. The findings demonstrate the feasibility of using electronic health record data to identify low-yield repetitive tests and offer personalized guidance for better usage of testing while ensuring high quality care.

Correction: From 2 dimensions to 3rd dimension: Quantitative prediction of anterior chamber depth from anterior segment photographs via deep-learning.

[This corrects the article DOI: 10.1371/journal.pdig.0000193.].

From 2 dimensions to 3rd dimension: Quantitative prediction of anterior chamber depth from anterior segment photographs via deep-learning.

Anterior chamber depth (ACD) is a major risk factor of angle closure disease, and has been used in angle closure screening in various populations. However, ACD is measured from ocular biometer or anterior segment optical coherence tomography (AS-OCT), which are costly and may not be readily available in primary care and community settings. Thus, this proof-of-concept study aims to predict ACD from low-cost anterior segment photographs (ASPs) using deep-learning (DL). We included 2,311 pairs of ASPs and ACD measurements for algorithm development and validation, and 380 pairs for algorithm testing. We captured ASPs with a digital camera mounted on a slit-lamp biomicroscope. Anterior chamber depth was measured with ocular biometer (IOLMaster700 or Lenstar LS9000) in data used for algorithm development and validation, and with AS-OCT (Visante) in data used for testing. The DL algorithm was modified from the ResNet-50 architecture, and assessed using mean absolute error (MAE), coefficient-of-determination (R2), Bland-Altman plot and intraclass correlation coefficients (ICC). In validation, our algorithm predicted ACD with a MAE (standard deviation) of 0.18 (0.14) mm; R2 = 0.63. The MAE of predicted ACD was 0.18 (0.14) mm in eyes with open angles and 0.19 (0.14) mm in eyes with angle closure. The ICC between actual and predicted ACD measurements was 0.81 (95% CI 0.77, 0.84). In testing, our algorithm predicted ACD with a MAE of 0.23 (0.18) mm; R2 = 0.37. Saliency maps highlighted the pupil and its margin as the main structures used in ACD prediction. This study demonstrates the possibility of predicting ACD from ASPs via DL. This algorithm mimics an ocular biometer in making its prediction, and provides a foundation to predict other quantitative measurements that are relevant to angle closure screening.

Anal margin cancer: current situation and ongoing trials.

PURPOSE OF REVIEW: To summarize the current treatment approach in managing anal margin cancer and to discuss potential emerging new strategies. RECENT FINDINGS: The management of anal margin cancer has been evolving over the past three decades. The treatment paradigm has been shifted from radical surgical resection to an organ-preservation approach. Multimodality strategies incorporating radiation or even chemoradiation are frequently considered in some cases. However, because of the rarity of the disease, the disease frequently remains an overlooked topic. At present, there is no prospective trial addressing the best clinical management of the disease. SUMMARY: The clinical course of squamous cell carcinoma of the anal margin is very different from that of the anal canal. The biology of anal margin cancer has not been actively explored and fully understood. There is a need to formulate a consensus approach for the clinical management of the disease. In addition, incorporation of new therapeutics in this disease especially in those with advanced stages should be explored.

c-Met represents a potential therapeutic target for personalized treatment in hepatocellular carcinoma.

UNLABELLED: c-Met, a high-affinity receptor for hepatocyte growth factor (HGF), plays a critical role in cancer growth, invasion, and metastasis. Hepatocellular carcinoma (HCC) patients with an active HGF/c-Met signaling pathway have a significantly worse prognosis. Although targeting the HGF/c-Met pathway has been proposed for the treatment of multiple cancers, the effect of c-Met inhibition in HCC remains unclear. The human HCC cell lines Huh7, Hep3B, MHCC97-L, and MHCC97-H were used in this study to investigate the effect of c-Met inhibition using the small molecule selective c-Met tyrosine kinase inhibitor PHA665752. MHCC97-L and MHCC97-H cells demonstrate a mesenchymal phenotype with decreased expression of E-cadherin and increased expression of c-Met, fibronectin, and Zeb2 compared with Huh7 and Hep3B cells, which have an epithelial phenotype. PHA665752 treatment blocked phosphorylation of c-Met and downstream phosphoinositide 3-kinase/Akt and mitogen-activated protein kinase/Erk pathways, inhibited cell proliferation, and induced apoptosis in c-Met-positive MHCC97-L and MHCC97-H cells. In xenograft models, administration of PHA665752 significantly inhibited c-Met-positive MHCC97-L and MHCC97-H tumor growth, and PHA665752-treated tumors demonstrated marked reduction of both c-Met phosphorylation and cell proliferation. c-Met-negative Huh7 and Hep3B cells were not affected by c-Met inhibitor treatment in vitro or in vivo. In addition, c-Met-positive MHCC97-L and MHCC97-H cells demonstrated cancer stem cell-like characteristics, such as resistance to chemotherapy, tumor sphere formation, and increased expression of CD44 and ABCG2, and PHA665752 treatment suppressed tumor sphere formation and inhibited CD44 expression. CONCLUSION: c-Met represents a potential target of personalized treatment for HCC with an active HGF/c-Met pathway.

Nanoliposomal ceramide prevents in vivo growth of hepatocellular carcinoma.

BACKGROUND AND OBJECTIVES: Hepatocellular carcinoma (HCC) affects an increasing number of people worldwide. The poor survival rate of patients with HCC is manifested by an aggressive and metastatic phenotype, as well as a poor response to common therapeutic strategies. The purpose of this study was to evaluate the efficacy of nanoliposomal C6-ceramide as an antineoplastic agent in an in vivo model of human HCC. METHODS: The growth-arresting and pro-apoptotic properties of nanoliposomal C6-ceramide were first evaluated in vitro in human SK-HEP-1 cells by assessing cellular viability, caspase 3/7 activity, annexin-V expression, DNA fragmentation, cell cycle distribution and AKT phosphorylation. SK-HEP-1 cells were then engrafted subcutaneously into athymic nude mice and nanoliposomal C6-ceramide was administered by tail vein injection. Tumour size was monitored over time, followed by excision of tumours to evaluate tumour vascularisation, proliferation, apoptosis and cellular signalling. RESULTS: Nanoliposomal C6-ceramide, but not ghost (no ceramide) nanoliposomes, induced apoptotic cell death of SK-HEP-1 cells in vitro, concomitant with an accumulation of cells in the G2 phase of the cell cycle and decreased phosphorylation of AKT. Systemic administration of nanoliposomal C6-ceramide to mice engrafted with SK-HEP-1 tumours reduced tumour vascularisation and proliferation, induced tumour cell apoptosis, decreased phosphorylation of AKT and ultimately blocked tumour growth. CONCLUSIONS: These studies show that nanoliposomal ceramide is an efficacious antineoplastic agent for the treatment of in vitro and in vivo models of human HCC.

Radiation Therapy and Malignant Fistulae of Anorectal Cancers.

PURPOSE: Although fistulization is a well-studied late toxic effect of radiation therapy (RT), anorectal cancers (ARCs) can present with malignant fistulae (MF) and negatively affect quality of life. The effect of RT, often combined with concurrent chemotherapy, on MF needs systematic analysis, because practitioners are concerned that RT may exacerbate MF. We reviewed our institutional series evaluating the hypothesis that RT worsens MF. METHODS AND MATERIALS: A single-institutional retrospective analysis of patients with ARC receiving RT from 2006 to 2019 was performed. These patients were screened for MF. Any MF resected before RT and RT not directed at the site of MF were excluded. Effects were assessed by review of available follow-up documentation and imaging. RESULTS: A total of 639 patients with ARC were reviewed, and 47 had MF (7.4%). With a median follow-up of 22 months (range, 2-133 months), RT improved MF in 17 of 29 evaluable patients (59%), with 9 of 29 (31.0%) having resolution. The median time to improvement was 50 days (range, 25-117 days); the median duration of improvement was 161 days (range, 0-1941 days). Malignant fistulae persisted in 12 of 29 patients (41%), with persistent local disease in all cases; in 2 cases, MF worsened concomitant with local progression. CONCLUSIONS: In all, 7.4% of patients with ARC presented with MF. Radiation therapy led to improvement or resolution in more than half of evaluable patients. Persistence or worsening of MF was only observed in patients with refractory or progressive local disease. Based on our findings, MF is not a contraindication to RT and may be considered as an independent indication for palliative RT.

Smartphone-Acquired Anterior Segment Images for Deep Learning Prediction of Anterior Chamber Depth: A Proof-of-Concept Study.

Purpose: To develop a deep learning (DL) algorithm for predicting anterior chamber depth (ACD) from smartphone-acquired anterior segment photographs. Methods: For algorithm development, we included 4,157 eyes from 2,084 Chinese primary school students (aged 11-15 years) from Mojiang Myopia Progression Study (MMPS). All participants had with ACD measurement measured with Lenstar (LS 900) and anterior segment photographs acquired from a smartphone (iPhone Xs), which was mounted on slit lamp and under diffuses lighting. The anterior segment photographs were randomly selected by person into training (80%, no. of eyes = 3,326) and testing (20%, no. of eyes = 831) dataset. We excluded participants with intraocular surgery history or pronounced corneal haze. A convolutional neural network was developed to predict ACD based on these anterior segment photographs. To determine the accuracy of our algorithm, we measured the mean absolute error (MAE) and coefficient of determination (R 2) were evaluated. Bland Altman plot was used to illustrate the agreement between DL-predicted and measured ACD values. Results: In the test set of 831 eyes, the mean measured ACD was 3.06 ± 0.25 mm, and the mean DL-predicted ACD was 3.10 ± 0.20 mm. The MAE was 0.16 ± 0.13 mm, and R 2 was 0.40 between the predicted and measured ACD. The overall mean difference was -0.04 ± 0.20 mm, with 95% limits of agreement ranging between -0.43 and 0.34 mm. The generated saliency maps showed that the algorithm mainly utilized central corneal region (i.e., the site where ACD is clinically measured typically) in making its prediction, providing further plausibility to the algorithm's prediction. Conclusions: We developed a DL algorithm to estimate ACD based on smartphone-acquired anterior segment photographs. Upon further validation, our algorithm may be further refined for use as a ACD screening tool in rural localities where means of assessing ocular biometry is not readily available. This is particularly important in China where the risk of primary angle closure disease is high and often undetected.

American Radium Society (ARS) Appropriate Use Criteria (AUC) for Locoregional Gastric Adenocarcinoma: Systematic Review and Guidelines.

OBJECTIVE: The objective of this study was to systematically evaluate the data regarding the use of neoadjuvant, perioperative, surgical, and adjuvant treatment options in localized gastric cancer patients and to develop Appropriate Use Criteria recommended by a panel of experts convened by the American Radium Society. METHODS: Preferred reporting items for systematic reviews and meta-analyses methodology was used to develop an extensive analysis of peer-reviewed phase 2/2R/3 trials, as well as meta-analyses found within the Ovid Medline database between 2010 and 2020. The expert panel then rated the appropriateness of various treatments in 5 representative clinical scenarios through a well-established consensus methodology (modified Delphi). RESULTS: For patients with medically operable locally advanced gastric cancer, the strongest recommendation was for perioperative chemotherapy based on high-quality data. Acceptable alternatives included surgery followed by either chemotherapy or concurrent chemoradiotherapy (CRT). For patients with upfront resection of stages I to III gastric cancer (no neoadjuvant therapy), the group strongly recommended adjuvant therapy with either chemotherapy alone or CRT, based on high-quality data. For patients with locally advanced disease who received preoperative chemotherapy without tumor regression, the group strongly recommended postoperative chemotherapy or postoperative CRT. Finally, for medically inoperable gastric cancer patients, there was moderate consensus recommending definitive concurrent CRT. CONCLUSIONS: The addition of chemotherapy and/or radiation, either in the neoadjuvant, adjuvant, or perioperative setting, results in improved survival rates for patients compared with surgery alone. For inoperable patients, definitive CRT is a reasonable treatment option, though largely palliative.

Multidisciplinary management of early and locally advanced esophageal cancer.

Clinical management of esophageal cancer is a multidisciplinary challenge. Diagnosis is associated with a high mortality and approximately 40% of patients have locally advanced disease at clinical presentation. Surgery remains one of the fundamental parts of treatment, but multimodal approaches including chemotherapy and radiation are associated with improved outcomes. This comprehensive review addresses the multidisciplinary management of early and locally advanced esophageal cancer.

Reirradiation for Rectal Cancer Using Pencil Beam Scanning Proton Therapy: A Single Institutional Experience.

PURPOSE: Reirradiation for rectal cancer (RC) after prior pelvic radiation therapy (RT) has been shown to be safe and effective. However, limited data exist for proton therapy (PT), including pencil beam scanning proton therapy (PBS-PT). We hypothesize that PT is safe and feasible for re-treatment and may allow for decreased toxicity and treatment escalation. METHODS AND MATERIALS: A single-institution, retrospective, institutional review board-approved analysis of all patients with RC and prior pelvic RT receiving PBS-PT reirradiation was performed. Data on patient and treatment characteristics and outcomes were collected. Local progression, progression-free survival, overall survival, and late grade >3 toxicity were estimated using the Kaplan-Meier method. RESULTS: Twenty-eight patients (median follow-up: 28.6 months) received PBS-PT reirradiation between 2016 and 2019, including 18 patients with recurrent RC (median prior dose: 54.0 Gy) and 10 patients with de novo RC and variable prior RT. The median reirradiation dose was 44.4 Gy (range, 16.0-60.0 Gy; 21 of 28 twice daily), and 24 of 28 patients received concurrent chemotherapy. Six underwent surgical resection. Three (10.7%) experienced grade 3 acute toxicities, and 1 did not complete RT owing to toxicity. Four (14.2%) had late grade <3 toxicity, including 1 grade 5 toxicity in a patient with a prior RT-related injury. The 1-year local progression, progression-free survival, and overall survival rates were 33.7% (95% confidence interval [CI], 14.5%-52.9%), 45.0% (95% CI, 26.2%-63.8%), and 81.8% (95% CI, 67.3%-96.3%), respectively. CONCLUSIONS: This is the largest series using PT for reirradiation for RC and the first study using PBS-PT. Low acute toxicity rates and acceptable late toxicity support PBS-PT as an option for this high-risk patient population, with a need for continued follow-up.