Is the Motion Causing a Commotion? Two-Fraction Prostate SBRT on the MR-Linac

PURPOSE/OBJECTIVE(S)

In HERMES (NCT04595019) men with localized prostate cancer are treated on the Unity MR-Linac platform (MRL, Elekta AB, Stockholm) and randomized between stereotactic body radiotherapy (SBRT) with 36.25 Gy in 5 fractions and 24 Gy in 2 fractions. Patients randomized to two fractions receive 24 Gy to the high risk PTV, 20 Gy to the low risk PTV and a boost of 27 Gy to the dominant intraprostatic lesion. This study explores dose received by the target and organs at risk (OARs) when considering intrafraction motion in two fraction SBRT.

MATERIALS/METHODS

Targets and OARs were delineated and a reference plan generated on Monaco v5.40.01 (Elekta). An Adapt-to-Shape (ATS) workflow was used. Contours were propagated to the session MRI (MRIsession) and edited accordingly. Prior to delivery, a verification MRI (MRIverif) was acquired with baseline shifts corrected for using the Adapt-to-Position (ATP-of-ATS) workflow. A post treatment MRI (MRIpost) was acquired after delivery. Men in the 2-fraction arm received each fraction in 2 sub-fractions sequentially on the same day, to mitigate intrafraction motion. The plans of 5 men receiving 2 fraction SBRT were analyzed. The targets, urethra, bladder and rectum were recontoured on the MRIverif and MRIpost. Delivered plans were recalculated on the corresponding MRIverif and MRIpost. The percentage of optimal and mandatory target dose constraints met were calculated. Accumulated OAR doses were calculated by averaging their respective dose statistics across all sub-fractions, conservatively assuming that the same area of the OAR receives the maximum dose each fraction. Analysis was carried out separately for MRIverif and MRIpost as the true 'delivered dose' most likely lies between these two estimates.

RESULTS

There was good coverage across all fractions. The mandatory constraints of CTVpsv V24.0 Gy > 95% and CTVsv V20.0 Gy > 95% were met in 100% of fractions and V2700cGy > 95% in 90% on the MRIpost. Table 3 shows OAR dose.

CONCLUSION

This work demonstrates that target coverage is good, even for the GTV where no margin is applied. With our conservative dose calculation approach, we found dose constraints are exceeded for some patients. However, treatment has been well tolerated, suggesting that that our current dose constraints may be cautious. Once Elekta's True Tracking and automated gating software is implemented at our center we will be able to further improve OAR clinical goal compliance.

Understanding the Benefit of Magnetic Resonance-guided Adaptive Radiotherapy in Rectal Cancer Patients: a Single-centre Study

AIMS

Neoadjuvant chemoradiotherapy followed by surgery is the mainstay of treatment for patients with rectal cancer. Standard clinical target volume (CTV) to planning target volume (PTV) margins of 10 mm are used to accommodate inter- and intrafraction motion of target. Treating on magnetic resonance-integrated linear accelerators (MR-linacs) allows for online manual recontouring and adaptation (MRgART) enabling the reduction of PTV margins. The aim of this study was to investigate motion of the primary CTV (CTVA; gross tumour volume and macroscopic nodes with 10 mm expansion to cover microscopic disease) in order to develop a simultaneous integrated boost protocol for use on MR-linacs.

MATERIALS AND METHODS

Patients suitable for neoadjuvant chemoradiotherapy were recruited for treatment on MR-linac using a two-phase technique; only the five phase 1 fractions on MR-linac were used for analysis. Intrafraction motion of CTVA was measured between pre-treatment and post-treatment MRI scans. In MRgART, isotropically expanded pre-treatment PTV margins from 1 to 10 mm were rigidly propagated to post-treatment MRI to determine overlap with 95% of CTVA. The PTV margin was considered acceptable if overlap was >95% in 90% of fractions. To understand the benefit of MRgART, the same methodology was repeated using a reference computed tomography planning scan for pre-treatment imaging.

RESULTS

In total, nine patients were recruited between January 2018 and December 2020 with T3a-T4, N0-N2, M0 disease. Forty-five fractions were analysed in total. The median motion across all planes was 0 mm, demonstrating minimal intrafraction motion. A PTV margin of 3 and 5mm was found to be acceptable in 96 and 98% of fractions, respectively. When comparing to the computed tomography reference scan, the analysis found that PTV margins to 5 and 10 mm only acceptably covered 51 and 76% of fractions, respectively.

CONCLUSION

PTV margins can be reduced to 3-5 mm in MRgART for rectal cancer treatment on MR-linac within an simultaneous integrated boost protocol.

Feasibility of tumour-focused adaptive radiotherapy for bladder cancer on the MR-linac

Bladder tumour-focused magnetic resonance image-guided adaptive radiotherapy using a 1.5 Tesla MR-linac is feasible. A full online workflow adapting to anatomy at each fraction is achievable in approximately 30 min. Intra-fraction bladder filling did not compromise target coverage with the class solution employed.

Trajectories of Alcohol Use and Related Harms for Managed Alcohol Program Participants over 12 Months Compared with Local Controls: A Quasi-Experimental Study

AIM

Investigate changes in alcohol use and related harm using the first multisite, controlled, longitudinal study of Managed Alcohol Programs (MAPs). MAPs provide regular doses of alcohol, accommodation, social supports and healthcare to unstably housed people with alcohol dependence.

METHODS

A multisite, quasi-experimental, longitudinal study was conducted in day centres, shelters and residential programs for unstably housed people. There were 59 MAP participants from six Canadian cities and 116 local controls. Self-reported alcohol consumption and harms were assessed at 0-2, 6 and 12 months. Liver function test results were accessed for MAP participants.

RESULTS

Both groups had similar reductions in mean drinks per day (MAP: -8.11; controls: -8.54 controls, P < 0.001) and days drinking per month (MAP: -2.51 days, P < 0.05; control: -4.81 days, P = 0.0001) over 6--12 months. Both reduced non-beverage alcohol consumption. MAP participants reported significantly fewer harms at both 0-2 and 6 months than controls. MAP participants had similar total consumption to controls, but spread out over more days (25.41 versus 19.64 days per month, P = 0.001). After leaving a MAP, participants' liver status deteriorated, with increases in both aspartate transaminase and bilirubin levels. MAP sites with effective policies on outside drinking drank less and had fewer harms.

CONCLUSION

MAP participants drank less hazardously than controls, especially with effective management of non-MAP drinking. Reductions in alcohol use and harms occurred for both groups, although MAP participants reported fewer harms at 0-6 months. Departing an MAP was associated with deterioration in liver status. Although providing stable housing, MAPs did not worsen health or increase alcohol use.

Feasibility of magnetic resonance guided radiotherapy for the treatment of bladder cancer

Whole bladder magnetic resonance image-guided radiotherapy using the 1.5 Telsa MR-linac is feasible. Full online adaptive planning workflow based on the anatomy seen at each fraction was performed. This was delivered within 45 min. Intra-fraction bladder filling did not compromise target coverage. Patients reported acceptable tolerance of treatment.

Heavy Drinkers and the Potential Impact of Minimum Unit Pricing-No Single or Simple Effect?

Aims

To explore the potential impact of a minimum unit price (MUP: 50 pence per UK unit) on the alcohol consumption of ill Scottish heavy drinkers.

Methods

Participants were 639 patients attending alcohol treatment services or admitted to hospital with an alcohol-related condition. From their reported expenditure on alcohol in their index week, and assuming this remained unchanged, we estimated the impact of a MUP (50 ppu) on future consumption. (Around 15% purchased from both the more expensive on-sale outlets (hotels, pubs, bars) and from off-sales (shops and supermarkets). For them we estimated the change in consumption that might follow MUP if (i) they continued this proportion of 'on-sales' purchasing or (ii) their reported expenditure was moved entirely to off-sale purchasing (to maintain consumption levels)).

Results

Around 69% of drinkers purchased exclusively off-sale alcohol at <50 ppu. Their drinking, post MUP, may reduce by a mean of 33%. For this group, from a population of very heavy, ill consumers, we were unable to show a differential effect across multiple deprivation quintiles. For other drinkers there might be no reduction, especially if after MUP there were many products priced close to 50 ppu. Moving away from on-sales purchases could support, for some, an increase in consumption.

Conclusions

While a proportion of our harmed, heavy drinkers might be able to mitigate the impact of MUP by changing purchasing habits, the majority are predicted to reduce purchasing. This analysis, focusing specifically on harmed drinkers, adds a unique dimension to the evidence base informing current pricing policy.

Short Summary

From drink purchasing data of heavy drinkers, we estimated the impact of legislating £0.50 minimum unit price. Over two thirds of drinkers, representing all multiple deprivation quintiles, were predicted to decrease alcohol purchasing; remainder, hypothetically, could maintain consumption. Our data address an important gap within the evidence base informing policy.

Alcohol purchasing by ill heavy drinkers; cheap alcohol is no single commodity

Objectives

Potential strategies to address alcohol misuse remain contentious. We aim to characterise the drink purchases of one population group: heavy drinkers in contact with Scottish health services. We contrast our findings with national sales data and explore the impact of socio-economic status on purchasing behaviour.

Study design

Cross-sectional study comparing alcohol purchasing and consumption by heavy drinkers in Edinburgh and Glasgow during 2012.

Methods

639 patients with serious health problems linked to alcohol (recruited within NHS hospital clinics (in- and out-patient settings) 345 in Glasgow, 294 in Edinburgh) responded to a questionnaire documenting demographic data and last week's or a ‘typical’ weekly consumption (type, brand, volume, price, place of purchase). Scottish Index of Multiple Deprivation quintile was derived as proxy of sociodemographic status.

Results

Median consumption was 184.8 (IQR = 162.2) UK units/week paying a mean of 39.7 pence per alcohol unit (£0.397). Off-sales accounted for 95% of purchases with 85% of those <50 pence (£0.5 UK) per alcohol unit. Corresponding figures for the Scottish population are 69% and 60%. The most popular low-priced drinks were white cider, beer and vodka with the most common off-sales outlet being the corner shop, despite supermarkets offering cheaper options. Consumption levels of the cheapest drink (white cider) were similar across all quintiles apart from the least deprived.

Conclusions

Heavy drinkers from all quintiles purchase the majority of their drinks from off-sale settings seeking the cheapest drinks, often favouring local suppliers. While beer was popular, recent legislation impacting on the sale of multibuys may prevent the heaviest drinkers benefiting from the lower beer prices available in supermarkets. Non-etheless, drinkers were able to offset higher unit prices with cheaper drink types and maintain high levels of consumption. Whilst price is key, heavy drinkers are influenced by other factors and adapt their purchasing as necessary.

•

We surveyed drinking behaviour in 639 patients with alcohol-related harm.

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Consumption was predominantly from off-sale settings (median = 184.8 UK units/week).

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Popular drinks were cheap varieties of white cider and vodka.

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Price and location of point of sale were key drivers of consumption.

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85% of units cost less that the proposed minimum unit price for alcohol.

A dose escalation (DE), pharmacokinetic (PK), and pharmacodynamic (PD) study of OSI-930 and erlotinib (E) in patients (pts) with advanced solid tumors

3550

Background: EGFR and VEGFR are important targets in a number of human cancers with common downstream signalling pathways. Combined blockade of EGFR-VEGFR with E and OSI-930 has shown additional antitumor activity compared to either agent alone with long-term remissions in multiple xenograft models. Methods: Sequential cohorts of pts with advanced refractory solid tumors were treated with OSI-930 BID with addition of E QD from Day 8 and beyond to determine the maximum tolerated dose (MTD) and to evaluate safety, PK and efficacy of the combination. Escalation followed a standard 3+3 design until dose-limiting toxicity (DLT) was observed in ≥ 2/6 pts. PK of OSI-930, E and its metabolite OSI-420 were determined. Levels of soluble VEGFR2 (sVEGFR2) in plasma were also measured. Results: 16 pts have been entered (13M/3F); median age 63 years (range 41–78), PS ≤2 and 38% pts with mCRC. OSI-930/E were administered at 3 levels [mg(pts entered/evaluable)]; 200 BID/100 QD (7/6), 200 BID/150 QD (4/3), and 300 BID/150 QD (5/5). Median duration of therapy was 8 weeks (range 1–22). DLT was seen in 1/6 pts at 200 BID/100 QD (>5 day interruption due to G4 neutropenia); and 1/5 at 300 BID/150 QD (G3 Asthenia/lethargy). Other common related toxicities (% all grades:% g3/4) were: skin-related (rash, HFS etc) (85:23), Asthenia/lethargy/fatigue (69:15), diarrhea (77:8), anorexia (92:0), and transaminitis (31:15). Reduction and/or interruptions of one or both study drugs during or beyond the initial 28 days were required in 8/14 pts. Six of 11 pts evaluable for response achieved SD ≥12 weeks. Median plasma Cmax (and AUCTau) of OSI -930 for Cohort 3 (300 BID/150 QD) were: 0.826 (6.08), 0.947 (5.57), and 1.66 (14.3) μg/mL (μg.hr/mL) on Days 7, 8 and 22, respectively. Exposure of OSI-930 increased approximately 2-fold upon co-administration with E at steady-state. OSI-930 appeared not to alter the PK properties of E or the ratio of OSI-420 to E. Decreases in plasma sVEGFR2 were observed, indicating a PD effect of OSI-930. Conclusions: Additional patients are being added to confirm the MTD of the combination. PK data indicate a drug-drug interaction with doubling of the OSI-930 exposure on co-administration with E.

[Table: see text]

Final results of a dose escalation (DE), pharmacokinetic (PK), and pharmacodynamic (PD) study of two schedules of OSI-930 in patients (pts) with advanced solid tumors

3564

Background: OSI-930 is an oral TKI with potent activity against Kit, VEGFR2, and PDGFR. Preclinical studies demonstrate tumor regression with long-term remissions across multiple xenograft models. Methods: Sequential cohorts of pts with advanced solid tumors received continuous daily OSI-930 to determine the maximum tolerated dose (MTD) and to evaluate safety, PK/PD and efficacy of OSI-930 with both QD and BID dosing. An expansion cohort was enrolled for detailed PD analysis including sVEGFR2 plasma levels, PET imaging in GIST pts or DCE-MRI in selected pts. Results: A total of 58 pts were treated (20M/38F; median 60 years (range 19–83)). OSI-930 was dosed up to 1600 mg QD without reaching MTD. 46 pts received BID dosing [mg(# pts treated)]; 400(7), 500 (31) and 600(8). DLT's were seen in 3/8 pts at 600 mg BID; G3 rash (2 pts) and G4 GGT; and 3/31 at 500 mg BID; G3 myalgia, G3 fatigue and G3 lipase. G3 hypertension was noted in 3/46 pts but not dose-limiting. Common G1/2 toxicities were fatigue (37%), diarrhea (27%), nausea (31%), and rash (24%). Objective (CA125) responses were seen in platinum-resistant ovarian cancer (2 PR/8) while in heavily pretreated GIST (median 4 prior therapies including imatinib/sunitinib), 8/18 pts achieved SD ≥12 w. Median therapy duration in the BID arm was 9 w and 18/46 pts with SD ≥12 w. PK indicated that Css were achieved after ∼7d with BID dosing. PET scans showed reduction in glycolytic activity in 4/9 pts and DCE-MRI response was seen in 4/6 pts. A trend in decreased sVEGFR levels was seen at higher doses. Conclusions: At the MTD level of 500 mg BID OSI-930 is an active, well-tolerated compound with clinically relevant antitumor activity and exposure levels consistent with antitumor activity in preclinical models. PD data indicate mechanistic proof of concept for OSI-930. OSI-930/erlotinib combination phase I study is currently enrolling.

[Table: see text]

A phase II study of single agent OSI-7904L in patients with metastatic or recurrent squamous cell carcinoma of the head and neck (SCCHN)

e17005

Background: Given the limited efficacy and relative toxicity of chemotherapy for metastatic or recurrent squamous cell carcinoma of the head and neck, further research is needed to both increase the efficacy and decrease the toxicity of treatment. OSI-7904L is a novel liposomal formulation of a non-competitive thymidylate synthase inhibitor. In a phase I study, 12 mg/m2 dosing given every 21 days was both feasible and well tolerated. Methods: This multi-center, two-stage, phase II trial was designed to assess the efficacy and toxicity of OSI-7904L in patients with advanced, refractory SCCHN. A total of 41 patients were to be enrolled by completion of stage II. Enrollment was limited to patients with histologically proven squamous histology, locally recurrent and/or metastatic disease, with no more than one prior chemotherapy regimen. Patients were required to have a performance status of ≤ 2, predicted life expectancy of at least three months and adequate hematopoietic, hepatic and renal function. Efficacy was assessed according to RECIST guidelines, and toxicity was evaluated per CTC AE 3.0. Results: Ten patients enrolled in stage 1. Median age was 60 (range 42–66). Nine were evaluable for response assessment with one withdrawn after one cycle due to a grade 4 papular rash. There were no objective responses while 4 of the 10 patients had stable disease during their first restaging. Median time to progression was 2.5 months for the 9 evaluable patients. Besides the one grade 4 dermatologic reaction, other toxicities were grade 3 fatigue and dehydration, and grade 2 anorexia. Assuming an expected 20% response rate required to initiate enrollment in stage II, the probability of the tenth patient being a responder was less than 3%, thus the study was closed due to lack of response in this population. Conclusions: OSI-7904L was well tolerated similar to the phase I data, but did not demonstrate efficacy in metastatic or recurrent HNSCC patients. Further study of this drug as a single-agent with the current dosing regimen is not recommended.

[Table: see text]