Evaluating the effect of short-course rifapentine-based regimens with or without enhanced behaviour-targeted treatment support on adherence and completion of treatment for latent tuberculosis infection among adults in the UK (RID-TB: Treat): protocol for an open-label, multicentre, randomised controlled trial.

INTRODUCTION: The successful scale-up of a latent tuberculosis (TB) infection testing and treatment programme is essential to achieve TB elimination. However, poor adherence compromises its therapeutic effectiveness. Novel rifapentine-based regimens and treatment support based on behavioural science theory may improve treatment adherence and completion. METHODS AND ANALYSIS: A pragmatic multicentre, open-label, randomised controlled trial assessing the effect of novel short-course rifapentine-based regimens for TB prevention and additional theory-based treatment support on treatment adherence against standard-of-care. Participants aged between 16 and 65 who are eligible to start TB preventive therapy will be recruited in England. 920 participants will be randomised to one of six arms with allocation ratio of 5:5:6:6:6:6: daily isoniazid +rifampicin for 3 months (3HR), routine treatment support (control); 3HR, additional treatment support; weekly isoniazid +rifapentine for 3 months (3HP), routine treatment support; weekly 3HP, additional treatment support ; daily isoniazid +rifapentine for 1 month (1HP), routine treatment support; daily 1HP, additional treatment support. Additional treatment support comprises reminders using an electronic pillbox, a short animation, and leaflets based on the perceptions and practicalities approach. The primary outcome is adequate treatment adherence, defined as taking ≥90% of allocated doses within the pre-specified treatment period, measured by electronic pillboxes. Secondary outcomes include safety and TB incidence within 12 months. We will conduct process evaluation of the trial interventions and assess intervention acceptability and fidelity and mechanisms for effect and estimate the cost-effectiveness of novel regimens. The protocol was developed with patient and public involvement, which will continue throughout the trial. ETHICS AND DISSEMINATION: Ethics approval has been obtained from The National Health Service Health Research Authority (20/LO/1097). All participants will be required to provide written informed consent. We will share the results in peer-reviewed journals. TRIAL REGISTRATION NUMBER: EudraCT 2020-004444-29.

Association of Bone Metastatic Burden With Survival Benefit From Prostate Radiotherapy in Patients With Newly Diagnosed Metastatic Prostate Cancer: A Secondary Analysis of a Randomized Clinical Trial.

IMPORTANCE: Prostate radiotherapy (RT) improves survival in men with low-burden metastatic prostate cancer. However, owing to the dichotomized nature of metastatic burden criteria, it is not clear how this benefit varies with bone metastasis counts and metastatic site. OBJECTIVE: To evaluate the association of bone metastasis count and location with survival benefit from prostate RT. DESIGN, SETTING, AND PARTICIPANTS: This exploratory analysis of treatment outcomes based on metastatic site and extent as determined by conventional imaging (computed tomography/magnetic resonance imaging and bone scan) evaluated patients with newly diagnosed metastatic prostate cancer randomized within the STAMPEDE trial's metastasis M1 RT comparison. The association of baseline bone metastasis counts with overall survival (OS) and failure-free survival (FFS) was assessed using a multivariable fractional polynomial interaction procedure. Further analysis was conducted in subgroups. INTERVENTIONS: Patients were randomized to receive either standard of care (androgen deprivation therapy with or without docetaxel) or standard of care and prostate RT. MAIN OUTCOMES AND MEASURES: The primary outcomes were OS and FFS. RESULTS: A total of 1939 of 2061 men were included (median [interquartile range] age, 68 [63-73] years); 1732 (89%) had bone metastases. Bone metastasis counts were associated with OS and FFS benefit from prostate RT. Survival benefit decreased continuously as the number of bone metastases increased, with benefit most pronounced up to 3 bone metastases. A plot of estimated treatment effect indicated that the upper 95% CI crossed the line of equivalence (hazard ratio [HR], 1) above 3 bone metastases without a detectable change point. Further analysis based on subgroups showed that the magnitude of benefit from the addition of prostate RT was greater in patients with low metastatic burden with only nonregional lymph nodes (M1a) or 3 or fewer bone metastases without visceral metastasis (HR for OS, 0.62; 95% CI, 0.46-0.83; HR for FFS, 0.57; 95% CI, 0.47-0.70) than among patients with 4 or more bone metastases or any visceral/other metastasis (HR for OS, 1.08; 95% CI, 0.91-1.28; interaction P = .003; HR for FFS, 0.87; 95% CI, 0.76-0.99; interaction P = .002). CONCLUSIONS AND RELEVANCE: In this exploratory analysis of a randomized clinical trial, bone metastasis count and metastasis location based on conventional imaging were associated with OS and FFS benefit from prostate RT in M1 disease. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00268476; ISRCTN.com Identifier: ISRCTN78818544.

The Automated Bone Scan Index as a Predictor of Response to Prostate Radiotherapy in Men with Newly Diagnosed Metastatic Prostate Cancer: An Exploratory Analysis of STAMPEDE's "M1|RT Comparison".

BACKGROUND: Prostate radiotherapy (RT) is a first-line option for newly diagnosed men with low-burden metastatic prostate cancer. The current criterion to define this clinical state is based on manual bone metastasis counts, but enumeration of bone metastases is limited by interobserver variations, and it does not account for metastasis volume or lesional coalescence. The automated bone scan index (aBSI) is a quantitative method of evaluating bone metastatic burden in a standardised and reproducible manner. OBJECTIVE: To evaluate whether aBSI has utility as a predictive imaging biomarker to define a newly diagnosed metastatic prostate cancer population that might benefit from the addition of prostate RT to standard of care (SOC) systemic therapy. DESIGN, SETTING, AND PARTICIPANTS: This is an exploratory analysis of men with newly diagnosed metastatic prostate cancer randomised in a 1:1 ratio to either SOC or SOC + prostate RT within the STAMPEDE "M1|RT comparison". INTERVENTION: The SOC was lifelong androgen deprivation therapy, with up-front docetaxel permitted from December 2015. Men allocated RT received either a daily or a weekly schedule that was nominated before randomisation. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Baseline bone scans were evaluated retrospectively to calculate aBSI. We used overall (OS) and failure-free (FFS) survival as the end points. Treatment-aBSI interaction was evaluated using the multivariable fractional polynomial interaction (MFPI) and subpopulation treatment effect pattern plot. Further analysis was done in aBSI quartiles using Cox regression models adjusted for stratification factors. RESULTS AND LIMITATIONS: Baseline bone scans for 660 (SOC: 323 and SOC + RT: 337) of 2061 men randomised within the "M1|RT comparison" met the software requirements for aBSI calculation. The median age was 68 yr, median PSA was 100 ng/mL, median aBSI was 0.9, and median follow-up was 39 mo. Baseline patient characteristics including aBSI were balanced between the treatment groups. Using the MFPI procedure, there was evidence of aBSI-treatment interaction for OS (p = 0.04, MFPI procedure) and FFS (p < 0.01, MFPI procedure). Graphical evaluation of estimated treatment effect plots showed that the OS and FFS benefit from prostate RT was greatest in patients with a low aBSI. Further analysis in quartiles based on aBSI supported this finding. CONCLUSIONS: A low automated bone scan index is predictive of survival benefit associated with prostate RT in men with newly diagnosed metastatic prostate cancer. PATIENT SUMMARY: The widely used bone scan can be evaluated using an automated technique to potentially select men with newly diagnosed metastatic prostate cancer who might benefit from prostate radiotherapy.