Identification of a Predictive Genomic Biomarker for Prostate-directed Therapy in Synchronous Low-volume Metastatic Castration-sensitive Prostate Cancer

BACKGROUND

Standard of care management for synchronous metastatic castration-sensitive prostate cancer (mCSPC) includes androgen deprivation therapy with a second-generation antiandrogen therapy and/or docetaxel. Recently, randomized data have demonstrated that prostate-directed therapy (PDT) is associated with an improvement in overall survival (OS) among patients with low-volume metastatic disease. Tumor genomics represents an additional dimension to define the clinical trajectory of patients with mCSPC.

OBJECTIVE

To evaluate a high-risk (HiRi) genomic signature to predict the benefit from PDT.

DESIGN, SETTING, AND PARTICIPANTS

We performed a single-institution retrospective review of men with synchronous low-volume mCSPC who underwent DNA panel sequencing of their tumor. Patients were classified according to the presence of HiRi mutation including pathogenic mutations in TP53, ATM, BRCA1, BRCA2, or Rb1.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoint was to determine the effect of PDT on OS in patients with and without a HiRi mutation. A survival analysis was performed with the Kaplan-Meier method compared with log-rank test and multivariable Cox regression. The interaction between HiRi mutation and PDT was evaluated.

RESULTS AND LIMITATIONS

A total of 101 patients with synchronous low-volume CSPC were included with a median follow-up of 44 mo. Approximately half of patients were found to have a HiRi pathogenic mutation (49%). Patients with HiRi mutations demonstrated median OS of 73 versus 66.8 mo (p = 0.3) for no PDT versus PDT. Conversely, patients without a HiRi mutation demonstrated a significant improvement in OS of 60 versus 105.3 mo (p < 0.001) for no PDT versus PDT. The p value for interaction for OS between PDT and HiRi mutation was statistically significant (p < 0.001). Limitations include the retrospective nature of the study.

CONCLUSIONS

Here, we have identified a HiRi genomic biomarker that appears predictive for the lack of benefit from PDT in men with synchronous low-volume mCSPC. Further work validating these results is warranted.

PATIENT SUMMARY

In this report, we evaluated a high-risk genomic biomarker to predict the benefit from prostate-directed therapy for men with synchronous low-volume metastatic castration-sensitive prostate cancer. We found that men without a high-risk mutation appear to experience a greater clinical benefit from prostate-directed therapy than those with a high-risk mutation.

TP53 structure-function relationships in metastatic castrate-sensitive prostate cancer and the impact of APR-246 treatment

PURPOSE

Despite well-informed work in several malignancies, the phenotypic effects of TP53 mutations in metastatic castration-sensitive prostate cancer (mCSPC) progression and metastasis are not clear. We characterized the structure-function and clinical impact of TP53 mutations in mCSPC.

PATIENTS AND METHODS

We performed an international retrospective review of men with mCSPC who underwent next-generation sequencing and were stratified according to TP53 mutational status and metastatic burden. Clinical outcomes included radiographic progression-free survival (rPFS) and overall survival (OS) evaluated with Kaplan-Meier and multivariable Cox regression. We also utilized isogenic cancer cell lines to assess the effect of TP53 mutations and APR-246 treatment on migration, invasion, colony formation in vitro, and tumor growth in vivo. Preclinical experimental observations were compared using t-tests and ANOVA.

RESULTS

Dominant-negative (DN) TP53 mutations were enriched in patients with synchronous (vs. metachronous) (20.7% vs. 6.3%, p < 0.01) and polymetastatic (vs. oligometastatic) (14.4% vs. 7.9%, p < 0.01) disease. On multivariable analysis, DN mutations were associated with worse rPFS (hazards ratio [HR] = 1.97, 95% confidence interval [CI]: 1.31-2.98) and overall survival [OS] (HR = 2.05, 95% CI: 1.14-3.68) compared to TP53 wild type (WT). In vitro, 22Rv1 TP53 R175H cells possessed stronger migration, invasion, colony formation ability, and cellular movement pathway enrichment in RNA sequencing analysis compared to 22Rv1 TP53 WT cells. Treatment with APR-246 reversed the effects of TP53 mutations in vitro and inhibited 22Rv1 TP53 R175H tumor growth in vivo in a dosage-dependent manner.

CONCLUSIONS

DN TP53 mutations correlated with worse prognosis in prostate cancer patients and higher metastatic potential, which could be counteracted by APR-246 treatment suggesting a potential future therapeutic avenue.

Clinical and Genomic Differences Between Advanced Molecular Imaging-detected and Conventional Imaging-detected Metachronous Oligometastatic Castration-sensitive Prostate Cancer

In metastatic castration-sensitive prostate cancer (mCSPC), disease volume plays an integral role in guiding treatment recommendations, including selection of docetaxel therapy, metastasis-directed therapy, and radiation to the prostate. Although there are multiple definitions of disease volume, they have commonly been studied in the context of metastases detected via conventional imaging (CIM). One such numeric definition of disease volume, termed oligometastasis, is heavily dependent on the sensitivity of the imaging modality. We performed an international multi-institutional retrospective review of men with metachronous oligometastatic CSPC (omCSPC), detected via either advanced molecular imaging alone (AMIM) or CIM. Patients were compared with respect to clinical and genomic features using the Mann-Whitney U test, Pearson's χ2 test, and Kaplan-Meier overall survival (OS) analyses with a log-rank test. A total of 295 patients were included for analysis. Patients with CIM-omCSPC had significantly higher Gleason grade group (p = 0.032), higher prostate-specific antigen at omCSPC diagnosis (8.0 vs 1.7 ng/ml; p < 0.001), more frequent pathogenic TP53 mutations (28% vs 17%; p = 0.030), and worse 10-yr OS (85% vs 100%; p < 0.001). This is the first report of clinical and biological differences between AMIM-detected and CIM-detected omCSPC. Our findings are particularly important for ongoing and planned clinical trials in omCSPC. PATIENT SUMMARY: Metastatic prostate cancer with just a few metastases only detected via newer scanning methods (called molecular imaging) is associated with fewer high-risk DNA mutations and better survival in comparison to metastatic cancer detected via conventional scan methods.

Developing the POTOMAC Model: A Novel Prediction Model to Study the Impact of Lymphopenia Kinetics on Survival Outcomes in Head and Neck Cancer Via an Ensemble Tree-Based Machine Learning Approach

PURPOSE

Lymphopenia is associated with poor survival outcomes in head and neck squamous cell carcinoma (HNSCC), yet there is no consensus on whether we should limit lymphopenia risks during treatment. To fully elucidate the prognostic role of baseline versus treatment-related lymphopenia, a robust analysis is necessary to investigate the relative importance of various lymphopenia metrics (LMs) in predicting survival outcomes.

METHODS

In this prospective cohort study, 363 patients were eligible for analysis (patients with newly diagnosed, nonmetastatic HNSCC treated with neck radiation with or without chemotherapy in 2015-2019). Data were acquired on 28 covariates: seven baseline, five disease, seven treatment, and nine LMs, including static and time-varying features for absolute lymphocyte count (ALC), neutrophil-to-lymphocyte ratio, and immature granulocytes (IGs). IGs were included, given their hypothesized role in inhibiting lymphocyte function. Overall, there were 4.0% missing data. Median follow-up was 2.9 years. We developed a model (POTOMAC) to predict survival outcomes using a random survival forest (RSF) procedure. RSF uses an ensemble approach to reduce the risk of overfitting and provides internal validation of the model using data that are not used in model development. The ability to predict survival risk was assessed using the AUC for the predicted risk score.

RESULTS

POTOMAC predicted 2-year survival with AUCs at 0.78 for overall survival (primary end point) and 0.73 for progression-free survival (secondary end point). Top modifiable risk factors included radiation dose and max ALC decrease. Top baseline risk factors included age, Charlson Comorbidity Index, Karnofsky Performance Score, and baseline IGs. Top-ranking LMs had superior prognostic performance when compared with human papillomavirus status, chemotherapy type, and dose (up to 2, 8, and 65 times higher in variable importance score).

CONCLUSION

POTOMAC provides important insights into potential approaches to reduce mortality in patients with HNSCC treated by chemoradiation but needs to be validated in future studies.

WNT Pathway Mutations in Metachronous Oligometastatic Castration-Sensitive Prostate Cancer

PURPOSE

WNT signaling is a cellular pathway that has been implicated in the development and progression of prostate cancer. Oligometastatic castration-sensitive prostate cancer (omCSPC) represents a unique state of disease in which metastasis-directed therapy (MDT) has demonstrated improvement in progression-free survival. Herein, we investigate the clinical implications of genomic alterations in the WNT signaling cascade in men with omCSPC.

METHODS AND MATERIALS

We performed an international multi-institutional retrospective study of 277 men with metachronous omCSPC who underwent targeted DNA sequencing of their primary/metastatic tumor. Patients were classified by presence or absence of pathogenic WNT pathway mutations (in the genes APC, RNF43, and CTNNB1). Pearson χ2 and Mann-Whitney U tests were used to determine differences in clinical factors between genomic strata. Kaplan-Meier survival curves were generated for radiographic progression-free survival and overall survival, stratified according to WNT pathway mutation status.

RESULTS

A pathogenic WNT pathway mutation was detected in 11.2% of patients. Patients with WNT pathway mutations were more likely to have visceral metastases (22.6% vs 2.8%; P < .01) and less likely to have regional lymph node metastases (29.0% vs 50.4%; P = .02). At time of oligometastasis, these patients were treated with MDT alone (33.9%), MDT + limited course of systemic therapy (20.6%), systemic therapy alone (22.4%), or observation (defined as no treatment for ≥6 months after metastatic diagnosis). Multivariable cox regression demonstrated WNT pathway mutations associated with significantly worse overall survival (hazard ratio, 3.87; 95% confidence interval, 1.25-12.00).

CONCLUSIONS

Somatic WNT pathway alterations are present in approximately 11% of patients with omCSPC and are associated with an increased likelihood of visceral metastases. Although these patients have a worse natural history, they may benefit from MDT.

The impact of salvage radiotherapy initiation at PSA ≤ 0.5 ng/ml on metastasis-free survival in patients with relapsed prostate cancer following prostatectomy

BACKGROUND AND PURPOSE

Salvage radiation therapy (SRT) is indicated for biochemical failure after radical prostatectomy. Prior data have shown that initiation of SRT at lower PSA levels improves subsequent biochemical control, yet given the long natural history of prostate cancer questions remain regarding optimal timing of SRT. We analyzed the impact of prostate specific antigen (PSA) level at time of salvage radiotherapy with regard to both biochemical relapse-free (bRFS) as well as metastasis-free survival (MFS) in patients with biochemically recurrent prostate cancer.

METHODS

Using prospective institutional tumor registry data, univariate and multivariable-adjusted Cox proportional hazards models were constructed to assess association between outcomes and clinical and pathologic prognostic features, including pre-SRT PSA, interval from prostatectomy to SRT, androgen deprivation therapy (ADT), and adverse pathologic features.

RESULTS

We identified 397 patients who received salvage RT between 1985 and 2016: 187 (45.8%) received SRT initiated when pre-RT PSA was ≤0.5 ng/ml; 212 (52.0%) patients had pre-SRT PSA > 0.5 ng/ml. Independent of pathologic risk status and ADT use, pre-SRT PSA ≤ 0.5 ng/ml was the most significant predictor of bRFS (HR 0.39, 95% CI [0.27, 0.56]) as well as MFS (HR = 0.58, 95% CI [0.37, 0.91]). Seminal vesicle invasion was also associated with shorter interval to biochemical failure, HR = 1.79, 95% CI [1.07, 2.98], and eventual metastases, HR = 2.07, 95% CI [1.14, 3.740].

CONCLUSIONS

Initiation of salvage RT while PSA levels remain ≤0.5 ng/ml was associated with improved MFS. Consideration for salvage RT initiation while PSA levels remain low is warranted to minimize risk of future prostate cancer metastasis.

Long-Term Outcomes and Genetic Predictors of Response to Metastasis-Directed Therapy Versus Observation in Oligometastatic Prostate Cancer: Analysis of STOMP and ORIOLE Trials

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The initial STOMP and ORIOLE trial reports suggested that metastasis-directed therapy (MDT) in oligometastatic castration-sensitive prostate cancer (omCSPC) was associated with improved treatment outcomes. Here, we present long-term outcomes of MDT in omCSPC by pooling STOMP and ORIOLE and assess the ability of a high-risk mutational signature to risk stratify outcomes after MDT. The primary end point was progression-free survival (PFS) calculated using the Kaplan-Meier method. High-risk mutations were defined as pathogenic somatic mutations within ATM, BRCA1/2, Rb1, or TP53. The median follow-up for the whole group was 52.5 months. Median PFS was prolonged with MDT compared with observation (pooled hazard ratio [HR], 0.44; 95% CI, 0.29 to 0.66; P value < .001), with the largest benefit of MDT in patients with a high-risk mutation (HR high-risk, 0.05; HR no high-risk, 0.42; P value for interaction: .12). Within the MDT cohort, the PFS was 13.4 months in those without a high-risk mutation, compared with 7.5 months in those with a high-risk mutation (HR, 0.53; 95% CI, 0.25 to 1.11; P = .09). Long-term outcomes from the only two randomized trials in omCSPC suggest a sustained clinical benefit to MDT over observation. A high-risk mutational signature may help risk stratify treatment outcomes after MDT.

Abstract 1971: Lymphocyte kinetics, frailty and survival outcomes in HNSCC

Lymphopenia is associated with decreased survival outcomes in head and neck squamous cell carcinoma (HNSCC). This is a significant concern especially for frail individuals who are more vulnerable to immunological dysregulations. A robust analysis is needed to understand whether we should expend efforts to limit treatment-related hematological toxicities in HNSCC.

First, we would like to understand the prognostic significance for baseline (BL) vs. treatment-related lymphopenia (TRL). We want to know if lymphopenia is merely a reflection of the patient’s frailty at baseline, or if this is iatrogenic and therefore can be a target for treatment modifications in a bid to improve survival. Here, we identified 222 newly diagnosed M0 HNSCC patients treated with radiation ± systemic therapy in 2015-2018 at our institution. Clinical frailty is defined by age ≥ 65 or KPS ≤ 70. Using Kaplan Meier estimates and Cox regression with dichotomous variables, we performed multivariate analysis for both overall survival (OS) and progression-free survival (PFS). Important predictors included frailty (p ≤ 0.002) and ≥ 2K/mm3 decrease in absolute lymphocyte counts (ALC) (p ≤ 0.006). BL did not significantly impact OS or PFS (p ≤ 0.37). For TRL, ALC decrease had greater prognostic significance compared with ALC nadirs (p ≤ 0.45).

Next, we simplified our survival model to include only frailty and TRL. Overall, fit patients with modest ALC decline (&lt; 2K/mm3) achieved excellent survival outcomes while frail patients with severe ALC decline (≥ 2K/mm3) had inferior outcomes (3-year OS 95% vs. 56%, p &lt; 0.0001; 3-year PFS 84% vs. 42%, p = 0.002). On subgroup analyses, similar outcomes were also identified for HPV+ HNSCC (n = 172, 3-year OS 96% vs. 71%, p = 0.002; 3-year PFS 89% vs. 54% p = 0.03).

Finally, we want to know if ALC decline is determined primarily by treatment intensity, or if frail patients are naturally predisposed to greater ALC decline during treatment. In our data, frail patients had more modest ALC decline when compared to fit patients (1.26 ± 0.57 vs. 1.54 ± 0.58 K/mm3 p = 0.0006). In our survival model, we did not observe any first-order interactions between frailty and ALC decline (p = 0.54). The extent of ALC decline was also higher for patients with concurrent administrations of cisplatin (as opposed to radiation alone, p &lt; 0.0001). Thus, we postulate that the extent of ALC decline is determined primarily by treatment intensity. It is possible that frail patients with severe ALC decline have inferior survival outcomes because they cannot maintain immunological balance and respond poorly when there is significant TRL. This opens opportunities to re-evaluate if the risk of TRL is modifiable by limiting the number of concurrent cycles of chemotherapy administered, and by considering radiation dose de-intensification especially for HPV-associated HNSCC. Lastly, TRL becomes an important consideration when immunotherapeutics are grafted onto existing CRT treatment paradigms.

Citation Format: Carmen Kut, Todd McNutt, Carole Fakhry, Theodore DeWeese, Harry Quon. Lymphocyte kinetics, frailty and survival outcomes in HNSCC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1971.

Establishing a Deaf and American Sign Language Inclusive Residency Program

Improving diversity in residency programs has been increasingly emphasized as a means to address gender, racial, and ethnic disparities in medicine. However, limited attention has been given to the potential benefits of training physicians with differences other than gender or race and ethnicity. Americans with a disability represent about 27% of the U.S. population, whereas 1%-3% of physician trainees report having a disability. In 2013, a national survey identified only 86 physicians or trainees reporting deafness or hearing loss as a disability. To date, there are no published strategies on how to create an inclusive program for Deaf trainees. Herein, the authors report on the development of a Deaf and American Sign Language (ASL) inclusive residency program that can serve as an academic model for other programs, in any medical specialty, seeking to create an accessible training program for Deaf physicians and that can be adapted for trainees with other disabilities. In March 2017, the radiation oncology residency program at Johns Hopkins University matched an ASL-signing Deaf resident who would begin the program in July 2018. In preparation, department leadership engaged key stakeholders and leaders within the university's health system and among the department faculty, residents, and staff as well as the incoming resident to create an ASL inclusive program. A 5-step transition process for the training program was ultimately developed and implemented. The authors focused on engaging the Deaf trainee and interpreters, engaging health system and departmental leadership, contracting a training consultant and developing oral and written training materials for faculty and staff, and optimizing the workspace via accommodations. Through collaborative preparation, a Deaf and ASL-signing resident was successfully integrated into the residency program. The proposed 5-step transition process provides an effective, engaging model to encourage other institutions that are seeking to employ similar inclusivity initiatives.

Impact of radiation dose on recurrence in high-risk prostate cancer patients

BACKGROUND

Dose escalated radiation therapy (RT) combined with long-term androgen deprivation therapy (ADT) is a standard of care option for men with high-risk and locally advanced prostate cancer (PCa). However, the optimal dose of escalated RT and ADT is not known. Here we assessed the impact of radiation dose and length of ADT on biochemical recurrence in a multi-institutional cohort stratified by the Cambridge prognostic group (CPG). We hypothesized that radiation dose and length of ADT would impact outcome in similar risk groups of our patients.

METHODS

Two-hundred and forty-four patients were included, 132 from Oslo University Hospital, Department of Oncology and 112 from Johns Hopkins Hospital, Department of Radiation Oncology. Biochemical recurrence was defined as prostate-specific antigen (PSA) nadir +2 ng/mL. Time to recurrence was estimated using Kaplan-Meier analysis and when stratified by CPG the log-rank test was used. Cox regression analysis was performed to identify factors associated with risk of recurrence. Site of recurrence was investigated.

RESULTS

The median follow-up time was 7.4 years. The vast majority (71%) of patients were classified as high-risk (CPG 4) or very high-risk features (CPG 5). Significantly more PSA recurrences occurred in CPG 5 (41%) compared with CPG 4 (25%) (P = .04) and five-year cumulative recurrence-free survival was lower for CPG 4 and 5 (89% and 68%) compared with CPG 1, 2, and 3 (100%, 100%, and 93%). The recurrence-free survival for CPG 5 was significantly higher for prostate irradiation of 80 Gy as compared with 74 Gy (P = .011). For CPG 4 and 5 no local recurrences were detected in patients receiving 80 Gy. On stepwise Cox regression analysis neither age nor length of ADT were independent prognostic factors for recurrence free survival.

CONCLUSION

Prostate dose escalation from 74 to 80 Gy decreases risk of recurrence in high-risk PCa. Further studies are needed to identify the optimal combination of ADT and RT.

Initial Impact and Operational Responses to the COVID-19 Pandemic by American Radiation Oncology Practices

PURPOSE

In February 2020, the COVID-19 pandemic reached the United States. The impact of the pandemic on the US radiation oncology field remains unknown. The American Society for Radiation Oncology surveyed US radiation oncology practice leaders to gauge initial impact and immediate operational responses to the pandemic.

METHODS AND MATERIALS

From April 16 to April 30, 2020, the American Society for Radiation Oncology surveyed US radiation oncology practice leaders by email to gauge initial impact and immediate operational responses to the COVID-19 pandemic.

RESULTS

Two hundred twenty-two (43%) of 517 leaders responded from community and academic practices (62% and 34%, respectively), hospital-based and free-standing centers (69% and 29%), and metro and rural locations (88% and 12%). Practices reported treating an average of 1086 patients per year in 2019 (range, 0-7900) with an average daily treatment volume of 70 patients (range, 5-400). All practices reported uninterrupted operation. On average, practices were treating 68% of their typical volume (range, 10%-95%), with 92% implementing planned treatment postponement for lower risk patients. An estimated revenue decrease of 20% or more was experienced by 71% of practices. Confirmed COVID-19 patient cases were treated by 39% of practices. Seventy percent experienced staff shortages. Almost all (98%) practices implemented formal operational procedures to protect patients and staff, although personal protective equipment/infection control supply shortages were reported by 78% of practices. Seventy-four percent used telemedicine for virtual follow-up surveillance, and 15% leveraged telemedicine for on-treatment assessment.

CONCLUSIONS

The clinical and financial impacts of the COVID-19 pandemic on US radiation oncology were deep and broad. Despite reported shortages in personal protective equipment, declines in revenue, and reduced patient volumes, practices adapted quickly by refining standard processes of care, implementing recommended safety measures, and employing telemedicine to facilitate treatment continuity. Patients with higher risk disease experienced uninterrupted access to care. We plan to continue regular surveying across the lifespan of the pandemic to document the geographic and temporal impact of COVID-19 on the field and its patients.

Needs and Challenges for Radiation Oncology in the Era of Precision Medicine

Modern medicine, including the care of the cancer patient, has significantly advanced, with the evidence-based medicine paradigm serving to guide clinical care decisions. Yet we now also recognize the tremendous heterogeneity not only of disease states but of the patient and his or her environment as it influences treatment outcomes and toxicities. These reasons and many others have led to a reevaluation of the generalizability of randomized trials and growing interest in accounting for this heterogeneity under the rubric of precision medicine as it relates to personalizing clinical care predictions, decisions, and therapy for the disease state. For the cancer patient treated with radiation therapy, characterizing the spatial treatment heterogeneity has been a fundamental tenet of routine clinical care facilitated by established database and imaging platforms. Leveraging these platforms to further characterize and collate all clinically relevant sources of heterogeneity that affect the longitudinal health outcomes of the irradiated cancer patient provides an opportunity to generate a critical informatics infrastructure on which precision radiation therapy may be realized. In doing so, data science-driven insight discoveries, personalized clinical decisions, and the potential to accelerate translational efforts may be realized ideally within a network of institutions with locally developed yet coordinated informatics infrastructures. The path toward realizing these goals has many needs and challenges, which we summarize, with many still to be realized and understood. Early efforts by our group have identified the feasibility of this approach using routine clinical data sets and offer promise that this transformation can be successfully realized in radiation oncology.

Using a real-time location system to measure patient flow in a radiation oncology outpatient clinic

PURPOSE

Common performance metrics for outpatient clinics define the time between patient arrival and entry into an examination room as "waiting time." Time spent in the room is considered processing time. This characterization systematically ignores time spent in the examination room waiting for service. If these definitions are used, performance will consistently understate total waiting times and overstate processing times. Correcting such errors will provide a better understanding of system behavior.

METHODS AND MATERIALS

In a radiation oncology service in an urban academic clinic, we collected data from a patient management system for 84 patients with 4 distinct types of visits: consultations, follow-ups, on-treatment visits, and nurse visits. Examination room entry and exit times were collected with a real-time location system for relevant care team members. Novel metrics of clinic performance were created, including the ratio of face time (ie, time during which the patient is with a practitioner) to total cycle time, which we label face-time efficiency. Attending physician interruptions occurred when the attending is called out of the room during a patient visit, and coordination-related delays are defined as waits for another team member.

RESULTS

Face-time efficiency levels for consults, follow-ups, on-treatment visits, and nurse visits were 30.1%, 22.9%, 33.0%, and 25.6%, respectively. Attending physician interruptions averaged 6.7 minutes per patient. If these interruptions were eliminated, face-time efficiencies would rise to 33.2%, 29.2%, 34.4%, and 25.6%, respectively. Eliminating all coordination-related delays would increase these values to 41.3%, 38.9%, 54.7%, and 38.7%, respectively.

CONCLUSIONS

A real-time location system can be used to augment a patient management system and automate data collection to provide improved descriptions of clinic performance.

An optimised spectrophotometric assay for convenient and accurate quantitation of intracellular iron from iron oxide nanoparticles

We report the development and optimisation of an assay for quantitating iron from iron oxide nanoparticles in biological matrices by using ferene-s, a chromogenic compound. The method is accurate, reliable and can be performed with basic equipment common to many laboratories making it convenient and inexpensive. The assay we have developed is suited for quantitation of iron in cell culture studies with iron oxide nanoparticles, which tend to manifest low levels of iron. The assay was validated with standard reference materials and with inductively coupled plasma-mass spectrometry (ICP-MS) to accurately measure iron concentrations ~1 × 10⁻⁶ g in about 1 × 10⁶ cells (~1 × 10⁻¹² g Fe per cell). The assay requires preparation and use of a working solution to which samples can be directly added without further processing. After overnight incubation, the absorbance can be measured with a standard UV/Vis spectrophotometer to provide iron concentration. Alternatively, for expedited processing, samples can be digested with concentrated nitric acid before addition to the working solution. Optimization studies demonstrated significant deviations accompany variable digestion times, highlighting the importance to ensure complete iron ion liberation from the nanoparticle or sample matrix to avoid underestimating iron concentration. When performed correctly, this method yields reliable iron ion concentration measurements to ~2 × 10⁻⁶ M (1 × 10⁻⁷ g/ml sample).

Continued Benefit to Rectal Separation for Prostate Radiation Therapy: Final Results of a Phase III Trial

PURPOSE

SpaceOAR, a Food and Drug Administration-approved hydrogel intended to create a rectal-prostate space, was evaluated in a single-blind phase III trial of image guided intensity modulated radiation therapy. A total of 222 men were randomized 2:1 to the spacer or control group and received 79.2 Gy in 1.8-Gy fractions to the prostate with or without the seminal vesicles. The present study reports the final results with a median follow-up period of 3 years.

METHODS AND MATERIALS

Cumulative (Common Terminology Criteria for Adverse Events, version 4.0) toxicity was evaluated using the log-rank test. Quality of life (QOL) was examined using the Expanded Prostate Cancer Index Composite (EPIC), and the mean changes from baseline in the EPIC domains were tested using repeated measures models. The proportions of men with minimally important differences (MIDs) in each domain were tested using repeated measures logistic models with prespecified thresholds.

RESULTS

The 3-year incidence of grade ≥1 (9.2% vs 2.0%; P=.028) and grade ≥2 (5.7% vs 0%; P=.012) rectal toxicity favored the spacer arm. Grade ≥1 urinary incontinence was also lower in the spacer arm (15% vs 4%; P=.046), with no difference in grade ≥2 urinary toxicity (7% vs 7%; P=0.7). From 6 months onward, bowel QOL consistently favored the spacer group (P=.002), with the difference at 3 years (5.8 points; P<.05) meeting the threshold for a MID. The control group had a 3.9-point greater decline in urinary QOL compared with the spacer group at 3 years (P<.05), but the difference did not meet the MID threshold. At 3 years, more men in the control group than in the spacer group had experienced a MID decline in bowel QOL (41% vs 14%; P=.002) and urinary QOL (30% vs 17%; P=.04). Furthermore, the control group were also more likely to have experienced large declines (twice the MID) in bowel QOL (21% vs 5%; P=.02) and urinary QOL (23% vs 8%; P=.02).

CONCLUSIONS

The benefit of a hydrogel spacer in reducing the rectal dose, toxicity, and QOL declines after image guided intensity modulated radiation therapy for prostate cancer was maintained or increased with a longer follow-up period, providing stronger evidence for the benefit of hydrogel spacer use in prostate radiation therapy.

Changes to physician processing times in response to clinic congestion and patient punctuality: a retrospective study

OBJECTIVES

We examine interactions among 3 factors that affect patient waits and use of overtime in outpatient clinics: clinic congestion, patient punctuality and physician processing rates. We hypothesise that the first 2 factors affect physician processing rates, and this adaptive physician behaviour serves to reduce waiting times and the use of overtime.

SETTING

2 urban academic clinics and an affiliated suburban clinic in metropolitan Baltimore, Maryland, USA.

PARTICIPANTS

Appointment times, patient arrival times, start of service and physician processing times were collected for 105 visits at a low-volume suburban clinic 1, 264 visits at a medium-volume academic clinic 2 and 22 266 visits at a high-volume academic clinic 3 over 3 distinct spans of time.

INTERVENTION

Data from the first clinic were previously used to document an intervention to influence patient punctuality. This included a policy that tardy patients were rescheduled.

PRIMARY AND SECONDARY OUTCOME MEASURES

Clinicians' processing times were gathered, conditioned on whether the patient or clinician was tardy to test the first hypothesis. Probability distributions of patient unpunctuality were developed preintervention and postintervention for the clinic in which the intervention took place and these data were used to seed a discrete-event simulation.

RESULTS

Average physician processing times differ conditioned on tardiness at clinic 1 with p=0.03, at clinic 2 with p=10^-5 and at clinic 3 with p=10^-7. Within the simulation, the adaptive physician behaviour degrades system performance by increasing waiting times, probability of overtime and the average amount of overtime used. Each of these changes is significant at the p<0.01 level.

CONCLUSIONS

Processing times differed for patients in different states in all 3 settings studied. When present, this can be verified using data commonly collected. Ignoring these behaviours leads to faulty conclusions about the efficacy of efforts to improve clinic flow.

HOXC10 Expression Supports the Development of Chemotherapy Resistance by Fine Tuning DNA Repair in Breast Cancer Cells

Development of drug resistance is a major factor limiting the continued success of cancer chemotherapy. To overcome drug resistance, understanding the underlying mechanism(s) is essential. We found that HOXC10 is overexpressed in primary carcinomas of the breast, and even more significantly in distant metastasis arising after failed chemotherapy. High HOXC10 expression correlates with shorter recurrence-free and overall survival in patients with estrogen receptor-negative breast cancer undergoing chemotherapy. We found that HOXC10 promotes survival in cells treated with doxorubicin, paclitaxel, or carboplatin by suppressing apoptosis and upregulating NF-κB Overexpressed HOXC10 increases S-phase-specific DNA damage repair by homologous recombination (HR) and checkpoint recovery in cells at three important phases. For double-strand break repair, HOXC10 recruits HR proteins at sites of DNA damage. It enhances resection and lastly, it resolves stalled replication forks, leading to initiation of DNA replication following DNA damage. We show that HOXC10 facilitates, but is not directly involved in DNA damage repair mediated by HR. HOXC10 achieves integration of these functions by binding to, and activating cyclin-dependent kinase, CDK7, which regulates transcription by phosphorylating the carboxy-terminal domain of RNA polymerase II. Consistent with these findings, inhibitors of CDK7 reverse HOXC10-mediated drug resistance in cultured cells. Blocking HOXC10 function, therefore, presents a promising new strategy to overcome chemotherapy resistance in breast cancer. Cancer Res; 76(15); 4443-56. ©2016 AACR.

Image-guided thermal therapy with a dual-contrast magnetic nanoparticle formulation: A feasibility study

PURPOSE/OBJECTIVE

The aim of this study was to develop and investigate the properties of a magnetic iron oxide nanoparticle-ethiodised oil formulation for image-guided thermal therapy of liver cancer.

MATERIALS AND METHODS

The formulation comprises bionised nano-ferrite (BNF) nanoparticles suspended in ethiodised oil, emulsified with polysorbate 20 (BNF-lip). Nanoparticle size was measured via photon correlation spectroscopy and transmission electron microscopy. In vivo thermal therapy capability was tested in two groups of male Foxn1(nu) mice bearing subcutaneous HepG2 xenograft tumours. Group I (n = 12) was used to screen conditions for group II (n = 48). In group II, mice received one of BNF-lip (n = 18), BNF alone (n = 16), or PBS (n = 14), followed by alternating magnetic field (AMF) hyperthermia, with either varied duration (15 or 20 min) or amplitude (0, 16, 20, or 24 kA/m). Image-guided fluoroscopic intra-arterial injection of BNF-lip was tested in New Zealand white rabbits (n = 10), bearing liver VX2 tumours. The animals were subsequently imaged with CT and 3 T MRI, up to 7 days post-injection. The tumours were histopathologically evaluated for distribution of BNF-lip.

RESULTS

The BNF showed larger aggregate diameters when suspended in BNF-lip, compared to clear solution. The BNF-lip formulation produced maximum tumour temperatures with AMF >20 kA/m and showed positive X-ray visibility and substantial shortening of T1 and T2 relaxation time, with sustained intratumoural retention up to 7 days post-injection. On pathology, intratumoural BNF-lip distribution correlated well with CT imaging of intratumoural BNF-lip distribution.

CONCLUSION

The BNF-lip formulation has favourable thermal and dual imaging capabilities for image-guided thermal therapy of liver cancer, suggesting further exploration for clinical applications.

A streamlined failure mode and effects analysis

PURPOSE

Explore the feasibility and impact of a streamlined failure mode and effects analysis (FMEA) using a structured process that is designed to minimize staff effort.

METHODS

FMEA for the external beam process was conducted at an affiliate radiation oncology center that treats approximately 60 patients per day. A structured FMEA process was developed which included clearly defined roles and goals for each phase. A core group of seven people was identified and a facilitator was chosen to lead the effort. Failure modes were identified and scored according to the FMEA formalism. A risk priority number,RPN, was calculated and used to rank failure modes. Failure modes with RPN > 150 received safety improvement interventions. Staff effort was carefully tracked throughout the project.

RESULTS

Fifty-two failure modes were identified, 22 collected during meetings, and 30 from take-home worksheets. The four top-ranked failure modes were: delay in film check, missing pacemaker protocol/consent, critical structures not contoured, and pregnant patient simulated without the team's knowledge of the pregnancy. These four failure modes had RPN > 150 and received safety interventions. The FMEA was completed in one month in four 1-h meetings. A total of 55 staff hours were required and, additionally, 20 h by the facilitator.

CONCLUSIONS

Streamlined FMEA provides a means of accomplishing a relatively large-scale analysis with modest effort. One potential value of FMEA is that it potentially provides a means of measuring the impact of quality improvement efforts through a reduction in risk scores. Future study of this possibility is needed.

The international cancer expert corps: a unique approach for sustainable cancer care in low and lower-middle income countries

The growing burden of non-communicable diseases including cancer in low- and lower-middle income countries (LMICs) and in geographic-access limited settings within resource-rich countries requires effective and sustainable solutions. The International Cancer Expert Corps (ICEC) is pioneering a novel global mentorship-partnership model to address workforce capability and capacity within cancer disparities regions built on the requirement for local investment in personnel and infrastructure. Radiation oncology will be a key component given its efficacy for cure even for the advanced stages of disease often encountered and for palliation. The goal for an ICEC Center within these health disparities settings is to develop and retain a high-quality sustainable workforce who can provide the best possible cancer care, conduct research, and become a regional center of excellence. The ICEC Center can also serve as a focal point for economic, social, and healthcare system improvement. ICEC is establishing teams of Experts with expertise to mentor in the broad range of subjects required to establish and sustain cancer care programs. The Hubs are cancer centers or other groups and professional societies in resource-rich settings that will comprise the global infrastructure coordinated by ICEC Central. A transformational tenet of ICEC is that altruistic, human-service activity should be an integral part of a healthcare career. To achieve a critical mass of mentors ICEC is working with three groups: academia, private practice, and senior mentors/retirees. While in-kind support will be important, ICEC seeks support for the career time dedicated to this activity through grants, government support, industry, and philanthropy. Providing care for people with cancer in LMICs has been a recalcitrant problem. The alarming increase in the global burden of cancer in LMICs underscores the urgency and makes this an opportune time fornovel and sustainable solutions to transform cancer care globally.

Abstract 635: Antigen-specific immune responses in melanoma using stereotactic radiotherapy combined with anti-PD1 checkpoint blockade

Purpose: Multiple pre-clinical studies and case reports have described potential synergy between radiotherapy and immunotherapy, including checkpoint blockade with anti-PD1 and anti-CTLA-4 antibodies. However, further understanding of how radiotherapy contributes to immune mediated cell death, especially with regards to timing and dose per fraction, is needed to guide protocols for clinical trials. Here we investigated the development of radiation induced antigen-specific immune responses (RASIR) using stereotactic image guided small animal radiotherapy combined with anti-PD1 checkpoint blockade in a B16 melanoma model.

Experimental Design: MC38 colorectal carcinoma, B16, and B16-OVA melanoma were cultured in complete RPMI media. A gamma-cell irradiator was used for in-vitro irradiation of cell suspensions. For in-vivo experiments 6-8 week old C57BL/6 mice were injected with 1x10^5 or 5x10^5 B16-OVA cells into the flank. Tumors were irradiated using a stereotactic CT guided small animal irradiator to treat a 1cmx1cm field prescribed to isocenter. For adoptive transfer experiments mice received 2x10^6 purified OT1 T-cells via retro-orbital injection. Anti-PD1 antibody was given intraperitoneally in three scheduled doses of 200ug. Cells were processed, stained, and analyzed by Flow cytometry on BD FACSCaliber or LSR II for indicated cell surface markers or intracellular cytokines.

Results: We found that irradiation with 10Gy or 20Gy increased cell surface expression of MHC Class I, CCR7, CXCR3, and FAS in MC38 colorectal carcinoma and B16 melanoma at 24 and 48 Hours. We observed in-vivo that stereotactic radiotherapy of B16-OVA melanoma tumors increased CFSE labeled proliferation and Interferon-gamma activation of adoptively transferred OT1 T-cells in the draining lymph node and spleen. 18 Gy of radiotherapy resulted in increased activation and proliferation of antigen-specific T-cells when compared to 12Gy suggesting a possible dose response. Furthermore, when radiotherapy was combined with scheduled anti-PD1 antibody there was near eradication of B16-OVA melanoma tumors accompanied by increased development of endogenous antigen-specific immune responses.

Conclusions: Radiotherapy increased expression of immunogenic cell surface markers in MC38 colorectal carcinoma and B16 melanoma. Stereotactic radiotherapy induced endogenous CD8 mediated antigen-specific immune responses when combined with scheduled anti-PD1 immunotherapy and resulted in near eradication of established B16-OVA melanoma. This study provides important pre-clinical evidence to support and guide clinical trials combining radiotherapy with anti-PD1 checkpoint blockade in melanoma. Future goals include analyzing development of RASIR using fractionated stereotactic radiotherapy with combined checkpoint blockade in multiple different tumor types.

Citation Format: Andrew Sharabi, Christopher Nirschl, Tina Ceccato, Brian Francica, Angela Alme, Thomas Nirschl, Esteban Velarde, Theodore DeWeese, Charles Drake. Antigen-specific immune responses in melanoma using stereotactic radiotherapy combined with anti-PD1 checkpoint blockade. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 635. doi:10.1158/1538-7445.AM2014-635

Prospective randomized phase 2 trial of intensity modulated radiation therapy with or without oncolytic adenovirus-mediated cytotoxic gene therapy in intermediate-risk prostate cancer

PURPOSE

To assess the safety and efficacy of combining oncolytic adenovirus-mediated cytotoxic gene therapy (OAMCGT) with intensity modulated radiation therapy (IMRT) in intermediate-risk prostate cancer.

METHODS AND MATERIALS

Forty-four men with intermediate-risk prostate cancer were randomly assigned to receive either OAMCGT plus IMRT (arm 1; n=21) or IMRT only (arm 2; n=23). The primary phase 2 endpoint was acute (≤90 days) toxicity. Secondary endpoints included quality of life (QOL), prostate biopsy (12-core) positivity at 2 years, freedom from biochemical/clinical failure (FFF), freedom from metastases, and survival.

RESULTS

Men in arm 1 exhibited a greater incidence of low-grade influenza-like symptoms, transaminitis, neutropenia, and thrombocytopenia than men in arm 2. There were no significant differences in gastrointestinal or genitourinary events or QOL between the 2 arms. Two-year prostate biopsies were obtained from 37 men (84%). Thirty-three percent of men in arm 1 were biopsy-positive versus 58% in arm 2, representing a 42% relative reduction in biopsy positivity in the investigational arm (P=.13). There was a 60% relative reduction in biopsy positivity in the investigational arm in men with <50% positive biopsy cores at baseline (P=.07). To date, 1 patient in each arm exhibited biochemical failure (arm 1, 4.8%; arm 2, 4.3%). No patient developed hormone-refractory or metastatic disease, and none has died from prostate cancer.

CONCLUSIONS

Combining OAMCGT with IMRT does not exacerbate the most common side effects of prostate radiation therapy and suggests a clinically meaningful reduction in positive biopsy results at 2 years in men with intermediate-risk prostate cancer.

Impact of a home-based walking intervention on outcomes of sleep quality, emotional distress, and fatigue in patients undergoing treatment for solid tumors

Exercise use among patients with cancer has been shown to have many benefits and few notable risks. The purpose of this study was to evaluate the impact of a home-based walking intervention during cancer treatment on sleep quality, emotional distress, and fatigue. Methods. A total of 138 patients with prostate (55.6%), breast (32.5%), and other solid tumors (11.9%) were randomized to a home-based walking intervention or usual care. Exercise dose was assessed using a five-item subscale of the Cooper Aerobics Center Longitudinal Study Physical Activity Questionnaire. Primary outcomes of sleep quality, distress, and fatigue were compared between the two study arms. Results. The exercise group (n = 68) reported more vigor (p = .03) than control group participants (n = 58). In dose response models, greater participation in aerobic exercise was associated with 11% less fatigue (p < .001), 7.5% more vigor (p = .001), and 3% less emotional distress (p = .03), after controlling for intervention group assignment, age, and baseline exercise and fatigue levels. Conclusion. Patients who exercised during cancer treatment experienced less emotional distress than those who were less active. Increasing exercise was also associated with less fatigue and more vigor. Home-based walking is a simple, sustainable strategy that may be helpful in improving a number of symptoms encountered by patients undergoing active treatment for cancer.

Initial validation and clinical experience with 3D optical-surface-guided whole breast irradiation of breast cancer

We had introduced 3D optical surface-guided radiotherapy (SGRT) of the breast cancer (BC). We then initiated the feasibility, accuracy, and precision studies of stereovision in detection of any breast displacement through the course of treatment for total thirty breasts undertaken whole breast irradiation (WBI). In the SGRT, CT-based plan data were parsed into an in-house computer program through which the reference surfaces were generated in 3D video format. When patients were positioned on treatment Tables, real-time stereovisions were rapidly acquired while the live surface tracking shown steady thorax motion. The real-time surface images were automatically aligned with the reference surface and detected shape and location changes of the breast were online corrected through the Table and beam adjustments. Accumulated dose to each patient was computed according to the frequency distribution of the measured breast locations during beam on time. Application of SGRT had diminished large skin-marking errors of > 5-mm and daily breast-setup errors of >10-mm that occurred on half of cases. Accuracy (mean) and precision (two standard deviations) of the breast displacements across the tangential field edges in the (U, V) directions were improved from (-0.5 ± 8.8,  2.2 ± 10.8) mm in conventional setup to (0.4 ± 4.6,  0.7 ± 4.4) mm in the final position while intra-fractional motion contributed only (0.1 ± 2.8, 0.0 ± 2.2) mm in free breathing. Dose uniformity and coverage to targets had both been increased by up to 10% and the lung or heart intersections have been decreased by half of those volumes if they were irradiated at the initial positions. SGRT of BC appears to be feasible regardless of skin tones, as fast as a snapshot for 3D imaging, and very accurate and precise for daily setup of flexible breast targets. Importantly, the technique allows us to verify the breast shape and position during beam-on time.

Abstract 5524: Radiosensitization of nanoparticle-based thermal delivery in mice bearing human prostate cancer

Heat is a potent sensitizer for radiation therapy. Technical hurdles associated with the selective and tumor-specific delivery of cytotoxic heat have precluded the widespread clinical adoption of heat as a therapeutic agent. Iron oxide magnetic nanoparticles have recently emerged as a promising alternative.

Male nude mice bearing PC3 tumors, a human prostate cancer cell line, were used for the study. A total of fifteen cohorts of mice, with ten mice per group, were used. Five groups received nanoparticle thermal therapy (no radiation) at varying thermal doses; four groups received the combination of heat with 5 Gy radiation within five minutes post thermal therapy; three groups received radiation only (5, 8, and 10 Gy); and, three groups served as controls (no treat, magnetic field only, and particles with 5 Gy but no magnetic field). Magnetic nanoparticles suspensions were injected directly into the tumors at doses 5, 2.5, and 1 mg Fe/g tumor. Two to four hours post-injection, the mice were anesthetized and placed in a helical solenoid alternating magnetic field coil. Particle heating was initiated by an AC field with frequency of 160 kHz and varying amplitudes of 600, 500, and 400 Oersteds for twenty minutes. The particle heat output varies with field amplitude. Cohorts of mice receiving combined radiation and heat therapy were given 5 Gy radiation within five minutes of thermal therapy. Tumor growth was monitored and growth delay and survival was measured. Intratumor and rectal temperatures were monitored in five mice of each heat therapy cohort with optical fiber-based temperature probes.

Complete tumor regression was observed for the 600 Oe and 5 mg Fe/g tumor combination, with local morbidity. Radiosensitization was achieved with lower thermal doses (400 Oe and 500 Oe with 5 mg Fe/g tumor) and no morbidity. For these cohorts, the heat alone was not effective. Tumor volume doubling time for 400 Oe and 5 mg Fe was 7 days (5 days for no treat control), and 10 days for 500 Oe and 5 mg Fe. However, the combination of 5 Gy (doubling time 22 days) with heat, even with the low thermal dose, produced significant tumor responses. For the combination of 400 Oe and 5 mg Fe with 5 Gy, tumor doubling time was increased to 32 days, and for the combination of 500 Oe with 5 mg Fe and 5 Gy, tumor volume failed to achieve doubling 45 days post therapy. Further study and analysis is ongoing and the results of their conclusions will be presented.

Magnetic nanoparticle-based heat delivery has the potential to sensitize tumors to radiation even with low thermal doses. This offers the potential to improve therapeutic response while simultaneously minimizing therapy-related morbidity.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5524.

Lack of an effect of high dose isoflavones in men with prostate cancer undergoing androgen deprivation therapy

PURPOSE

The profound hypogonadism due to androgen deprivation therapy for prostate cancer results in complications such as sexual dysfunction, poor quality of life, vasomotor symptoms and altered cognition. Since estrogen is associated with cardiovascular risks, phytoestrogens are being increasingly evaluated as a potential treatment for these adverse effects. We evaluated the effects of high dose isoflavones, equivalent to that consumed by Asian populations, on the aforementioned consequences of androgen deprivation therapy.

MATERIALS AND METHODS

A total of 33 men undergoing androgen deprivation therapy for prostate cancer were enrolled in this randomized, double-blind, placebo controlled, 12-week pilot trial. Participants were randomly assigned to receive 20 gm soy protein containing 160 mg total isoflavones (17) vs taste matched placebo, that is 20 gm whole milk protein (16). The study was performed at a tertiary care center in the United States.

RESULTS

At baseline the groups were well matched in demographic parameters, sleep quality, cognition and overall quality of life. However, men in the isoflavone group had a higher baseline prevalence of hot flashes and poor intercourse satisfaction compared to those on placebo. At 12 weeks there were no significant differences between the 2 groups in any outcome measure.

CONCLUSIONS

This pilot study of high dose isoflavones in androgen deprived men showed no significant improvement in cognition, vasomotor symptoms or any other aspect of quality of life measures compared to placebo. Future studies should use variable doses of isoflavones for a longer period before ruling out beneficial isoflavone effects in this population.

Phase I trial with a combination of docetaxel and 153Sm- EDTMP in patients (pts) with castration-resistant metastatic prostate cancer (mCRPC)

5155

Background: Bone targeted therapy holds great promise for improving outcomes in mCRPC. Preclinical data strongly supported biological synergism of docetaxel (Tax) and 153Sm-EDTMP (Sm) in mCRPC. Concurrent Tax and Sm regimens were reported feasible and tolerable in phase I studies. This study was designed to evaluate toxicity and preliminary efficacy of 2 cycles (12 wks/cycle, C) of concomitant standard dose/schedule of Sm plus Q3 wks schedule of Tax in mCRPC. Methods: mCRPC pts with progressive bone metastases were treated in 4 cohorts ( CH). Previous Tax and palliative RT to bone was admissible. Dose escalation of Tax was implemented if no DLT was observed in the preceding CH. Tax doses (on days 1, 22, per 12 wk cycle) were given as follows: CH 1- 50mg/m2 (C1 and 2); CH 2–75mg/m2 (C1) and 50mg/m2 (C2); CH3 - 75mg/m2 (C1 and 2) and CH4 ( Tax day 1, 22, 43 per 12 wk C) 75mg/m2 (C1 and 2). Sm was administered on days 2 (Q12 wks X 2) at dose of 1 mCi/kg/cycle (max. of 2 cycles). Disease status was assessed (with bone /CT scans and PSA) after every cycle. Results: Thirteen pts with progressive bone metastases were enrolled. Three had prior Tax and 3 had prior palliative radiation. Thirteen pts received total 20 cycles in 4 cohorts. Toxicity was primarily hematological. There were total 34 episodes Grade 3/4 neutropenia with a median 7 (range 7 -14) days to recovery to ≤ grade1. Tax dose was reduced to 50% in 2 CH4 pts at C2. Only 1 DLT G3 thrombocytopenia occurred on cohort 4 with duration of 9 wks. Median baseline PSA was 100.4 ng/ml (range 8.6 - 1064), 9/13 (69%) pts had PSA>50% decrease. Median time to disease progression was 147 days (range 72 days - 10 months+); 6/13 (46%) pts had stable/improved bone scans at 6 months and 8/8 (100%) symptomatic pts had improvement in pain. Conclusions: Concurrent 6-month administration of 2 and possibly 3 full dose /standard schedule of Tax with 2 full doses of Sm is feasible with reversible bone marrow suppression. The combination may provide additional clinical benefits for mCRPC pts with extensive bone metastasis.

No significant financial relationships to disclose.