Optimal size threshold for PIRADSv2 category 5 upgrade and its positive predictive value: is it predictive of "very high" likelihood of clinically-significant cancer?

AIM

To identify the optimal size metric and threshold for Prostate Imaging Reporting and Data System (PIRADS) 5 upgrade, calculate its positive predictive value (PPV) for clinically-significant prostate cancer (csPCA), and determine if it is indicative of a "very high" likelihood of csPCA.

MATERIALS AND METHODS

One hundred and forty-three PIRADS 4 or 5 lesions were evaluated. Lesion diameters were used to calculate lesion volume (LV). Pearson correlation between maximum lesion diameter (MLD) and LV was calculated. Area under the curve (AUC) for discriminating csPCA (Gleason grade ≥ 3 + 4) was calculated using MLD and LV. Optimal size thresholds (using Youden index) and highly predictive size thresholds were identified for the whole prostate (WP), peripheral zone (PZ), and transitional zone (TZ).

RESULTS

There was high correlation between MLD and LV (r=0.77-0.81), with comparable AUCs for MLD and LV in the identification of csPCA in the WP (0.73, 0.72), PZ (0.73, 0.73), and TZ (0.79, 0.75). Optimal MLD thresholds were 1.4, 1.4, and 1.6 cm in the WP, PZ, and TZ respectively, with PPVs of 76%, 81%, and 69%, respectively. An MLD threshold of 2.7 cm would be needed in the WP to achieve a PPV approaching 90%, with sensitivity decreasing to 10%.

CONCLUSIONS

There is high correlation between MLD and LV with comparable discrimination of csPCA using each. PIRADSv2's 1.5 cm MLD threshold is near the optimal threshold for PIRADS 5 upgrade but has moderate PPV. A much higher threshold would be needed to increase its PPV, with significant sacrifice in sensitivity.

Focal Boosted IMRT Treatment of Prostate Cancer to 84 Gy in 28 Fractions: Preliminary Clinical Outcomes and Dosimetry

PURPOSE/OBJECTIVE(S)

The FLAME trial reported that focal boosting of prostate tumor to 95 Gy in 35 fractions improves biochemical control. However, this treatment is not commonly used in the United States. We investigated a focally boosted treatment of 84 Gy in 28 fractions (EQD2 108 Gy, BED 252 Gy).

MATERIALS/METHODS

Between 2019-2022, men with unfavorable intermediate risk (uIR) and high risk (HR) prostate cancer were enrolled on a prospective registry and received a novel IMRT regimen. The dose levels were 84 Gy to the gross tumor volume (GTV) as defined on mpMRI (T2W and ADC) with no added margin, 70 Gy to the prostate and proximal seminal vesicles, and optional 50.4 Gy to elective pelvic lymph nodes (all 28 fractions). Patients received fiducial markers and hydrogel spacer. The treatment planning goal was to cover 95% of the GTV at 84 Gy, and also meet the target and normal tissue dosimetry criteria of the hypofractionated treatment arm of NRG-GU005. VMAT was used for treatment delivery. ADT was given at the discretion of the treating physician.

RESULTS

A total of 20 men were included in the study, 2 (10%) uIR and 18 (90%) HR. 9 (45%) tumors were GS 7, 7 (35%) were GS 8, and 4 (20%) were GS 9. There were 13 (65%) stage cT1, 4 (20%) cT2 and 3 (15%) cT3. One (5%) patient received short term ADT, 18 (95%) long term ADT, and 1 (5%) refused ADT. 18 (90%) men received elective nodal radiation. The mean baseline PSA was 25.1 (range 4.2-73.4). The median baseline IPSS score was 11.1 (IQR 4.5-12), and 4 patients had severe baseline urinary symptoms (IPSS ≥20). The mean baseline prostate volume was 57.4 cc (range 26.8-198.3). The mean volume of the 84 Gy boost target was 7.1 cc (range 2.3-15.0) and the mean proportion of the prostate boosted was 14.8% (range 2% - 47%). There were 10 (50%) men with 1 boost target, 6 (30%) with two, 3 (15%) with three, and 1 (5%) had 4 boost targets. Targets were located in peripheral zone (85%), transition zone (30%), and central zone (5%). Patients met all per-protocol normal tissue criteria of NRG-GU005, except for bladder D0.03cc. The mean±SD (Gy) rectum D15%, D25%, and D30% were 51±5, 45±5, 42±4. The mean±SD (Gy) bladder D0.03cc, D30%, D50% were 79±4, 50±8, 38±10. At a median follow up time of 21.3 months (range 7.1-38.2), no patients have developed biochemical progression, local recurrence, distant progression, or death from prostate cancer. One patient died at 18 months from metastatic colorectal cancer, unrelated to prostate cancer treatment. Acute grade 1-2 GU toxicity occurred in 13 (65%) patients, and acute grade 1-2 GI toxicity occurred in 4 (20%) patients. No patients developed grade 3+ acute or late GU or GI toxicity. Two patients required temporary foley catheter for obstruction during RT, and both had IPSS >20 at baseline. The patient who refused ADT had a PSA bounce of magnitude 2.2 ng/mL at 14 months, PSA values declined without additional treatment.

CONCLUSION

A novel 28-fraction focal boosted IMRT treatment is feasible and has an acceptable early toxicity profile. Oncologic results are promising but require longer follow up.

Prediction of Progression After Cervix Cancer Radiotherapy Using a Machine-Learning Model on Pre-Treatment MRI

PURPOSE/OBJECTIVE(S)

MRI may be useful to identify women with cervical cancer at high risk of disease progression to test strategies of treatment intensification. The purpose of this study was to determine the value of a machine-learning model built on pre-treatment MRI for prediction of risk of progression after radiation therapy.

MATERIALS/METHODS

MagneticResonance Imaging (MRI) data for women with cervical cancer was collected from The Cancer Genome Atlas Cervical Squamous Cell Carcinoma and Endocervical Adenocarcinoma Collection (TCGA-CESC) on the Cancer Imaging Archive (TCIA), which reported clinical, treatment, and imaging data from a single institution. 27 patients who had received radiation for cervical cancer were selected for input into a custom 3-D Residual Neural Network (ResNet) model with added custom layers specific to DICOM data in tensorflow python package. One T2 MRI per patient was used to predict recurrence free survival after radiation treatment, where patients were predicted to be "high risk" or "low risk" for disease recurrence as the output of the model. All slices of the T2 MRI were used. The model was validated using five-fold cross validation; 80% of the data was used to train each fold and 20% was used for testing. Final model statistical significance was confirmed through shuffle test at the p < 0.01 level. The clinical outcomes of patients and the model's "low-risk" and "high-risk" prediction were compared.

RESULTS

There were 27 patients in the study with mean age of 51 years (range 29-79). 20 patients had squamous cell carcinoma and 7 patients had adenocarcinoma. The stage breakdown consisted of 9 women IB, 2 IIA, 9 IIB, 2 IIIA, 2 IIIB, and 3 stage IV. 10 women were treated with radiation alone and 17 with chemo-radiation. 5 women received surgery in addition to radiation or chemoradiation. 21 patients received brachytherapy. Median follow-up of patients was 29 months (range 3-64). The model predicted 7 patients as "high risk" for recurrence; all 7 developed a recurrence during follow up. None of the 20 patients predicted to be "low risk" developed disease recurrence. Among all patients in the study, the two-year progression free survival (PFS) was 82.0%. Patients identified as "low risk" and "high risk" by model had two-year PFS of 100% and 43%, respectively. Among patients with recurrence, 3 developed local recurrence and 4 developed distant metastases. The ResNet model achieved cross-validated accuracy of 92% for prediction of progression-free survival (p<0.01).

CONCLUSION

A 3-D ResNet machine-learning model using pretreatment MRI image data can accurately predict clinical outcomes for cervical cancer following radiation therapy. Future work to confirm generalizability should focus on validation with a larger clinical dataset.

Improvement in Disease Activity in Refractory Juvenile Dermatomyositis Following Abatacept Therapy

OBJECTIVE

An open-label 24-week study was conducted to evaluate the safety and efficacy of abatacept in patients with refractory juvenile dermatomyositis (JDM).

METHODS

Ten patients >7 years of age with moderate disease activity were enrolled in a 24-week study to examine the safety and treatment response of subcutaneous abatacept. The primary endpoint was the International Myositis Assessment and Clinical Studies Group (IMACS) Definition of Improvement (DOI). Secondary endpoints included safety, change in core set activity measures (CSMs) of IMACS and Pediatric Rheumatology International Trials Organization (PRINTO), and the ACR-EULAR response criteria for JDM. Blinded radiologists assessed thigh magnetic resonance imaging (MRI). Interferon gene score (IFNGS) was performed on whole-blood RNA by NanoString and cytokines were assessed by Luminex.

RESULTS

Five patients achieved DOI at week 12, and nine achieved DOI at week 24, including two with minimal, four moderate, and three with major improvement by ACR-EULAR response criteria using IMACS CSMs. All CSMs improved from baseline at weeks 12 and 24, except muscle enzymes. Daily corticosteroid dose decreased from a mean of 16.7 mg at baseline to 10.2 mg at week 24 (p=0.002). Average MRI muscle edema score decreased from baseline 5.3 to 2.3 at week 24 (p=0.01). Six patients had down-trending IFNGS and galectin-9 at week 24. Decreases in IFNGS, IP-10, galectin-9 and IL-2 correlated with improvement in disease activity and in MRI muscle edema. Eleven Grade 2 or 3 treatment-emergent adverse events were observed.

CONCLUSIONS

This open-label study demonstrated abatacept may be beneficial for treatment-refractory JDM.

Infarct Involution and Improved Function During Healing of Acute Myocardial Infarction: The Role of Microvascular Obstruction #,?

Delayed contrast-enhanced cardiac magnetic resonance imaging (ceCMR) delineates infarct size. The presence of hypoenhancement consistent with microvascular obstruction (MO) signifies larger infarcts with a worse prognosis. We hypothesized that the size of the contrast defect (CD) on ceCMR in acutely infarcted myocardium may change during infarct healing and depend upon the presence of MO. Twenty-five patients underwent CMR on weeks 1 and 8 after reperfused myocardial infarction. After short-axis cine CMR was performed, gadolinium was infused and ceCMR images and matched tagged cine MR images were obtained in the three most dysfunctional short-axis slices on cine CMR. The area and transmural extent of hyperenhancement (HE) with or without MO representing total CD size were planimetered. Between week 1 and week 8, the CD area fell from 1729+/-970 mm2 at week 1 to 1270+/-706 mm2 (p<0.001), as did the transmural extent of infarction (71+/-22% to 63+/-24%, p<0.001). The decline in CD trended to be higher in patients with MO (840+/-807 mm2) than in HE (312+/-485 mm2, p<0.07). In the patient group as a whole, ejection fraction (EF) improved (56+/-9% to 60+/-10%, p=0.002) between weeks 1 and 8, but patients with MO showed no increase in EF. Segments with some HE demonstrated partial functional improvement whereas no improvement was seen in HE+MO segments. In patients 8 weeks after reperfused myocardial infarction (MI), the size of infarction by ceCMR decreases compared to week 1 post-MI, especially in those with microvascular obstruction in whom there is little improvement in regional or global function.

Comparative molecular field analysis and QSAR on substrates binding to cytochrome P450 2D6

In this study, we utilized comparative molecular field analysis (CoMFA) to gain a better understanding of the steric and electrostatic features of the cytochrome p450 2D6 (CYP2D6) active site. The training set consists of 24 substrates with reported K(M) values from liver microsomal CYP2D6 spanning an activity range of almost three log units. The low energy conformers were fit by root mean square (RMS) to minaprine at the site of metabolism and to the protonated nitrogen. In this manner, we constructed two CoMFA models, one model with a distance constraint and another without. The model with the distance parameter (non-cross-validated R(2)=0.99) was approximately equal to the CoMFA without a distance parameter (non-cross-validated R(2)=0.98). Validation of our CoMFA was accomplished by predicting the K(M) values of 15 diverse CYP2D6 substrates not in the original training set resulting in a predictive R(2)=0.62. Finally, we also pursued correlations of pK(a) and log P with CYP2D6 substrate K(M) in an effort to investigate other physicochemical properties.