Phase 2 study of add-on parsaclisib for patients with myelofibrosis and suboptimal response to ruxolitinib: final results

ABSTRACT

Ruxolitinib reduces spleen volume, improves symptoms, and increases survival in patients with intermediate- or high-risk myelofibrosis. However, suboptimal response may occur, potentially because of signaling via the phosphoinositide 3-kinase (PI3K)/protein kinase B pathway. This phase 2 study evaluated dosing, efficacy, and safety of add-on PI3Kδ inhibitor parsaclisib for patients with primary or secondary myelofibrosis with suboptimal response to ruxolitinib. Eligible patients remained on a stable ruxolitinib dose and received add-on parsaclisib 10 or 20 mg, once daily for 8 weeks, and once weekly thereafter (daily-to-weekly dosing; n = 32); or parsaclisib 5 or 20 mg, once daily for 8 weeks, then 5 mg once daily thereafter (all-daily dosing; n = 42). Proportion of patients achieving a ≥10% decrease in spleen volume at 12 weeks was 28% for daily-to-weekly dosing and 59.5% for all-daily dosing. Proportions of patients achieving ≥50% decrease at week 12 in Myelofibrosis Symptom Assessment Form and Myeloproliferative Neoplasms Symptom Assessment Form symptom scores were 14% and 18% for daily-to-weekly dosing, and 28% and 32% for all-daily dosing, respectively. Most common nonhematologic treatment-emergent adverse events were nausea (23%), diarrhea (22%), abdominal pain and fatigue (each 19%), and cough and dyspnea (each 18%). New-onset grade 3 and 4 thrombocytopenia were observed in 19% of patients, each dosed daily-to-weekly, and in 26% and 7% of patients dosed all-daily, respectively, managed with dose interruptions. Hemoglobin levels remained steady. The addition of parsaclisib to stable-dose ruxolitinib can reduce splenomegaly and improve symptoms, with manageable toxicity in patients with myelofibrosis with suboptimal response to ruxolitinib. This trial was registered at www.clinicaltrials.gov as #NCT02718300.

MPN-075 Efficacy and Safety of Add-on Parsaclisib to Ruxolitinib Therapy in Myelofibrosis Patients With Low Versus Higher Baseline Platelet Counts: A Subgroup Analysis of Data From a Phase 2 Study

CONTEXT

Ruxolitinib (JAK inhibitor) is effective in myelofibrosis, but suboptimal responses occur potentially from PI3K/AKT activation. In INCB50465-201 (NCT02718300), add-on parsaclisib (PI3Kδ inhibitor) showed preliminary efficacy in myelofibrosis patients. JAK inhibitors are associated with thrombocytopenia and patients with low platelet count (PC) are generally difficult to treat.

OBJECTIVE

Evaluate efficacy and safety of add-on parsaclisib in a subgroup analysis of study INCB50465-201 by baseline PC.

DESIGN

Open-label, phase 2.

SETTING

Clinical study.

PATIENTS

Primary/secondary myelofibrosis patients with a suboptimal response (palpable spleen >10 cm below left subcostal margin [LSM]; or palpable spleen 5-10 cm below LSM and active symptoms) after ≥6 months of receiving ruxolitinib (5-25 mg BID; stable dose ≥8 weeks).

INTERVENTIONS

Patients on stable ruxolitinib dose randomized to either add-on parsaclisib 10 or 20 mg QD for 8 weeks then same dose QW or parsaclisib 5 or 20 mg QD for 8 weeks then 5 mg QD.

MAIN OUTCOME MEASURES

Spleen volume (SV), Myelofibrosis-Symptoms Assessment Form Total Symptom Score (MFSAF-TSS v3.0), and safety based on baseline PC (low PC, 50-<100×10⁹/L; higher PC, ≥100×10⁹/L).

RESULTS

At data cutoff (08/27/2020), 67 patients (low PC, n=21; higher PC, n=46) were enrolled. For low versus higher PC, the median prior duration of ruxolitinib treatment was 34.7 versus 14.9 months and baseline median (range) MFSAF-TSS was 21.4 (0.6-47) versus 10.0 (0-43), respectively. For low versus higher PC patients: 9/18 (50%) versus 15/38 (39.4%) had spleen volume reduction (SVR) ≥10% at week 12, 6/17 (35.2%) versus 13/35 (37.1%) at week 24; 0 versus 1 had SVR ≥35% at week 12, 2 versus 1 at week 24; median change in MFSAF-TSS was -20.5% versus -22.2% at week 12, -26.1% versus -23.1% at week 24, respectively. Nonhematologic treatment-emergent adverse events were mostly grade 1 or 2; most common (≥25%) were dyspnea (7/21, 33%), falls (7/21, 33%), and peripheral edema (6/21, 29%) for low PC; diarrhea (13/46, 28%) for higher PC. Thrombocytopenia led to parsaclisib interruption in 9/21 low-PC versus 3/46 higher-PC patients and ruxolitinib interruption in 1/21 low-PC patients.

CONCLUSIONS

Add-on parsaclisib showed promising efficacy and combination therapy was generally well-tolerated in myelofibrosis patients with low or higher baseline PC.

Targeting the PI3K pathway in myeloproliferative neoplasms

INTRODUCTION

Decreasing efficacy over time and initial suboptimal response to Janus kinase (JAK) inhibitors such as ruxolitinib in a subset of patients are critical clinical challenges associated with myeloproliferative neoplasms (MPNs), primarily myelofibrosis.

AREAS COVERED

The role of phosphatidylinositol-3 kinase (PI3K) in MPN disease progression and treatment resistance and as a potential therapeutic target in patients who experience loss of response to JAK inhibition is discussed. Understanding the complex signaling networks involved in the pathogenesis of MPNs has identified potentially novel therapeutic targets and treatment strategies, such as inhibiting other signaling pathways in addition to the JAK/signal transducer and activator of transcription (STAT) pathway. PI3K plays a crucial role downstream of JAK signaling in rescuing tumor cell proliferation, with PI3Kδ being particularly important in hematologic malignancies. Concurrent targeting of both PI3K and JAK/STAT pathways may offer an innovative therapeutic strategy to maximize efficacy.

EXPERT OPINION

Based on our understanding of the underlying mechanisms and the role of PI3K pathway signaling in the loss of response or resistance to JAK inhibitor treatment and initial results from clinical studies, the combination of parsaclisib (PI3Kδ inhibitor) and ruxolitinib holds great clinical potential. If confirmed in larger clinical trials, parsaclisib may provide more treatment options and improve clinical outcomes for patients with MPNs.

Abstract CT541: Efficacy and safety of parsaclisib-ruxolitinib combination therapy in myelofibrosis patients (Pts) with low vs higher baseline platelet count (PC): A subgroup analysis of data from a phase 2 study

Background: Myelofibrosis (MF) pts often exhibit suboptimal response to chronic ruxolitinib therapy, possibly due to persistent PI3K pathway activation. In the ongoing phase 2 INCB 50465-201 trial (NCT02718300), add on parsaclisib (potent, highly selective PI3Kδ inhibitor) is showing preliminary efficacy in MF pts with suboptimal ruxolitinib response. JAK inhibitors (eg, ruxolitinib), are associated with thrombocytopenia; therefore, pts with low PC are commonly more difficult to treat. We present a subgroup analysis of efficacy and safety data from INCB 50465-201 by baseline PC.

Methods: Eligible adults had primary/secondary MF with suboptimal response (palpable spleen &gt;10 cm below left subcostal margin [LSM]; or palpable spleen 5-10 cm below LSM and active symptoms) after ≥6 months of ruxolitinib monotherapy (5-25 mg BID; stable dose ≥8 wks). Pts remained on their last stable ruxolitinib dose and received add on parsaclisib (10 or 20 mg QD for 8 wks; same dose QW thereafter) or parsaclisib (5 or 20 mg QD for 8 wks; 5 mg QD thereafter). For this analysis, spleen volume (SV), total symptom score (TSS) assessed by Myelofibrosis-Symptoms Assessment Form (MFSAF) v3.0 daily diary, and safety, were evaluated by baseline PC (low PC, 50-&lt;100 × 109/L; higher PC, ≥100 × 109/L).

Results: At data cutoff (8/27/2020), 67 pts were enrolled (low PC, n=21; higher PC, n=46; median age 68 y). For low vs higher PC, median prior duration of ruxolitinib use was 34.7 vs 14.9 months; baseline symptoms were worse for low PC vs higher PC (median [range] MFSAF-TSS, 21.4 [0.6-47] vs 10 [0-43]). For low vs higher PC, 9/18 (50.0%) vs 15/38 (39.4%) pts had SV reduction (SVR) ≥10% at wk 12; percentages of pts with SVR ≥10% were similar at wk 24 (6/17 [35.2%] vs 13/35 [37.1%]); 0 vs 1 pt had SVR ≥35% at wk 12; 2 vs 1 pt had SVR ≥35% at wk 24. Of pts with ≥10% SVR at wk 24, 4/6 with low PC and 9/13 with higher PC were on all daily dosing regimens. For low vs higher PC, median (range) percentage change in MFSAF-TSS was −20.5 (−56.6 to +17.1) vs −22.2 (−100 to +500) at wk 12; −26.1 (−54.7 to +2.4) vs −23.1 (−91.3 to +222.5) at wk 24. In both subgroups, nonhematologic treatment-emergent adverse events (TEAEs) were mostly grade 1/2. Most common (≥20%) TEAEs were dyspnea (33%), falls (33%), peripheral edema (29%), and nasal congestion (24%) for low PC; diarrhea (28%), nausea (24%), abdominal pain (24%), cough (20%), and fatigue (20%) for higher PC. For low vs higher PC, 9/21 (43%) vs 3/46 (7%) pts had parsaclisib dose interruption due to thrombocytopenia; 1 pt with low PC had ruxolitinib interruption due to thrombocytopenia.

Conclusion: Add-on parsaclisib showed efficacy in pts from both low and higher baseline PC groups. Given the acceptable safety profile and efficacy of add-on parsaclasib, MF pts with both low and higher PC may be able to benefit from parsaclisib-ruxolitinib combination therapy.

Citation Format: Abdulraheem Yacoub, Uma Borate, Raajit Rampal, Haris Ali, Eunice Wang, Aaron Gerds, Gabriela Hobbs, Marina Kremyanskaya, Elliott Winton, Casey O’Connell, Swati Goel, Stephen Oh, Gary Schiller, Albert Assad, Sue Erickson-Viitanen, Feng Zhou, Naval Daver. Efficacy and safety of parsaclisib-ruxolitinib combination therapy in myelofibrosis patients (Pts) with low vs higher baseline platelet count (PC): A subgroup analysis of data from a phase 2 study [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 CT541.

Abstract CT162: Addition of parsaclisib (INCB050465), a PI3Kδ inhibitor, in patients with suboptimal response to ruxolitinib: A phase 2 study in patients with myelofibrosis

Background: Ruxolitinib improves outcomes in patients (pts) with myelofibrosis (MF); however, suboptimal response may occur due to persistent PI3K/AKT pathway activation despite continued JAK inhibition. This phase 2 study (NCT02718300) evaluated optimal dosing and efficacy of add-on parsaclisib, a potent, highly selective next-generation PI3Kδ inhibitor, in pts with MF and suboptimal ruxolitinib response. Methods: Patients had primary/secondary MF, ECOG ≤2, and suboptimal response (palpable spleen &gt;10 cm below left subcostal margin [LSM]; or palpable spleen 5-10 cm below LSM and active symptoms) after ≥6 months of ruxolitinib (5-25 mg BID; stable dose, ≥8 weeks [wks]). Patients remained on their stable ruxolitinib dose and were randomized to add-on parsaclisib QD/QW (10 or 20 mg QD for 8 wks/same dose QW thereafter) or parsaclisib QD (5 or 20 mg QD for 8 wks/5 mg QD thereafter). Endpoints: baseline-to-wk-12 spleen volume (SV) change by MRI/CT (primary endpoint); spleen length and symptom changes (Myelofibrosis-Symptoms Assessment Form Total Symptom Score [MFSAF-TSS]). Results: At data cutoff (1/20/2020), 33 pts received parsaclisib QD/QW; 20 received QD (median treatment duration, 197 days; median average daily doses: parsaclisib, 4.9 mg/day; ruxolitinib, 30.0 mg/day). Baseline median (range) SV (cm3) was 2333 (327-5324) in QD/QW (n=30) and 1890 (434-3741) in QD (n=17); median MFSAF-TSS was 10.8 (n=28) and 18.7 (n=17). In QD/QW and QD, median percent SV change was −2.3 (n=30) and −15.4 (n=17) at wk 12; and −2.5 (n=24) and −25.4 (n=9) at wk 24. In QD/QW and QD, number of pts with wk 12 SV reduction ≥10% were 10/30 (33%) and 10/17 (59%); ≥25% were 1/30 (3%) and 4/17 (24%); and ≥35% were 0 and 1/17 (6%). Median percent change in MFSAF-TSS at wk 12 was −14.0 (n=21) in QD/QW; −39.6 (n=12) in QD. Nonhematologic AEs were primarily grade 1/2. Grade 3/4 treatment-related, nonhematologic AEs included disseminated tuberculosis, enteritis, fatigue, hypertension, increased alanine aminotransferase, and increased aspartate aminotransferase in QD/QW and stomatitis in QD. In QD/QW and QD, 6/33 and 6/20 pts had new-onset grade 3 thrombocytopenia; 7/33 and 0/20 pts had grade 4 thrombocytopenia; hemoglobin levels remained steady during the study in both groups. Serious treatment-related AEs were stomatitis, herpes zoster infection, varicella zoster infection, and disseminated tuberculosis (each n=1). No colitis/dose-limiting diarrhea/rash occurred. In QD/QW and QD, 18/33 and 10/20 pts interrupted parsaclisib, and 4/33 and 4/20 interrupted ruxolitinib for AEs. Conclusions: Add-on parsaclisib showed efficacy in pts with MF experiencing suboptimal ruxolitinib response; QD dosing appeared more efficacious than QD/QW dosing. Combination therapy demonstrated acceptable safety with limited grade 3/4 AEs and no dose-limiting AEs.

Citation Format: Abdulraheem Yacoub, Eunice S. Wang, Raajit K. Rampal, Uma Borate, Marina Kremyanskaya, Haris Ali, Gabriela S. Hobbs, Casey O'Connell, Albert Assad, Sue Erickson-Viitanen, Feng Zhou, Timothy C. Burn, Naval G. Daver. Addition of parsaclisib (INCB050465), a PI3Kδ inhibitor, in patients with suboptimal response to ruxolitinib: A phase 2 study in patients with myelofibrosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT162.

Abstract CT253: A Randomized, Double-Blind, Placebo-Controlled Phase 3 Study of Parsaclisib Plus Ruxolitinib in Patients with Myelofibrosis Who Have Suboptimal Response to Ruxolitinib

Background: Ruxolitinib (JAK1/JAK2 inhibitor) is indicated for the treatment of adults with intermediate (INT) or high-risk myelofibrosis (MF), including primary MF, post-polycythemia vera MF and post-essential thrombocythemia MF, but a subset of patients may exhibit a suboptimal response due to possible persistent PI3K/AKT activation. Targeting PI3K/AKT signaling may therefore have clinically relevant effects on MF disease burden. This phase 3, randomized, double-blind, placebo-controlled study will determine the effect of add-on parsaclisib, a highly selective PI3Kδ inhibitor, on signs and symptoms of MF in patients with suboptimal or declining response to stable ruxolitinib treatment (INCB 50465-304; NCT04551053). Methods: Eligible patients are aged ≥18 years with a diagnosis of at least INT-1-risk category according to the Dynamic International Prognostic Scoring System (DIPSS; Passamonti. Blood. 2010;115:1703-1708) primary or secondary (post-polycythemia vera or post-essential thrombocythemia) MF, have received ruxolitinib for ≥3 months with a stable dose (5-25 mg twice daily) for ≥8 weeks prior to receiving the first dose of study drug (Day 1), have evidence of suboptimal response to ruxolitinib (palpable spleen ≥5 cm below left subcostal margin, and total symptom score ≥10), and ECOG PS ≤2. Patients are excluded if they received prior therapy with any PI3K inhibitor, experimental or standard drug therapy for MF (except ruxolitinib) within 3 months of starting study drug, or have platelet count &lt;50×109/L, recent history of inadequate bone marrow reserve, or inadequate liver or renal function at screening. Approximately 212 patients on a stable dose of ruxolitinib will be randomized (1:1) to receive add-on parsaclisib 5 mg daily or matching placebo beginning on Day 1, with stratification by platelet count (≥100×109/L or 50 to &lt;100×109/L) and DIPSS risk category (high, INT-2, or INT-1) at randomization. Treatment will continue as long as tolerated and discontinuation criteria are not met. Upon patient completion of 24 weeks of treatment, he/she will be unblinded and if randomized to ruxolitinib plus placebo and with adequate hematology parameters, the patient will be able to crossover to receive ruxolitinib plus add-on parsaclisib. The primary objective is to evaluate and compare the efficacy of add-on parsaclisib versus placebo on spleen volume at Week 24. Secondary objectives are to evaluate and compare the effect of add-on parsaclisib versus placebo on: patient-reported MF symptoms, overall survival, time to onset and duration of spleen volume response, and safety and tolerability. Sites are opening throughout the US, EU, China and Japan.

Citation Format: Abdulraheem Yacoub, Michael Stouffs, Feng Zhou, Albert Assad. A Randomized, Double-Blind, Placebo-Controlled Phase 3 Study of Parsaclisib Plus Ruxolitinib in Patients with Myelofibrosis Who Have Suboptimal Response to Ruxolitinib [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT253.

A phase 3, randomized, double-blind, placebo-controlled study of ruxolitinib plus parsaclisib in patients with JAK- and PI3K-inhibitor treatment-naïve myelofibrosis

TPS7058

Background: Ruxolitinib (JAK1/JAK2 inhibitor) significantly improves outcomes in patients with myelofibrosis (MF); however, a subset of patients may experience a suboptimal response. Recent phase 2 data showed that addition of PI3Kδ inhibitor parsaclisib to ruxolitinib monotherapy resulted in additional alleviation of MF symptoms and splenomegaly in patients with MF (Yacoub. EHA2020. S216). This phase 3, randomized, double-blind study (INCB 50465-313; NCT04551066), evaluates the combination of ruxolitinib and parsaclisib in patients with MF who are naïve to Janus kinase (JAK) and PI3K inhibitor therapies. Methods: Eligible patients are aged ≥18 years with a diagnosis of primary MF, post-polycythemia vera MF, or post-essential thrombocythemia MF, have a Dynamic International Prognostic Scoring System (DIPSS; Passamonti. Blood. 2010;115:1703-1708) risk category of at least Intermediate (INT)-1, palpable spleen ≥5 cm below left subcostal margin; total symptom score ≥10 at screening, ECOG PS 0–2, and life expectancy ≥24 weeks. Patients will be excluded if they previously received therapy with any JAK inhibitor, any PI3K inhibitor, any experimental or standard drug therapy for MF ≤3 months of first study dose and/or lack of recovery from all toxicities related to previous therapies to grade ≤1, have recent history of inadequate bone marrow reserve (eg, platelet count = 50×109/L) or have inadequate liver or renal function at screening. Approximately 440 patients will be randomized (1:1) to ruxolitinib plus parsaclisib 5 mg QD or ruxolitinib plus matching placebo, with stratification at randomization by DIPSS risk category (high vs INT-2 vs INT-1) and platelet count (≥100×109/L vs 50 to = 100×109/L inclusive). Treatment will begin on Day 1, with starting ruxolitinib dose level determined by baseline platelet count, and will continue as long as treatment is tolerated and discontinuation criteria are not met. When the last enrolled patient has completed 24 weeks of treatment, the study will be unblinded and patients randomized to ruxolitinib plus placebo who have adequate hematology parameters will be able to crossover to receive parsaclisib together with continued ruxolitinib. The primary objective is the evaluation and comparison of spleen volume at Week 24 for patients who received ruxolitinib plus parsaclisib versus ruxolitinib plus placebo. Secondary objectives include evaluation and comparison of patient-reported MF symptoms, overall survival, time to onset and duration of response in spleen volume, and safety and tolerability for ruxolitinib plus parsaclisib versus ruxolitinib plus placebo. Sites are opening across the United States, Europe, Asia, and New Zealand. Clinical trial information: NCT04551066.

Splenomegaly Segmentation on Multi-Modal MRI Using Deep Convolutional Networks

The findings of splenomegaly, abnormal enlargement of the spleen, is a non-invasive clinical biomarker for liver and spleen diseases. Automated segmentation methods are essential to efficiently quantify splenomegaly from clinically acquired abdominal magnetic resonance imaging (MRI) scans. However, the task is challenging due to: 1) large anatomical and spatial variations of splenomegaly; 2) large inter- and intra-scan intensity variations on multi-modal MRI; and 3) limited numbers of labeled splenomegaly scans. In this paper, we propose the Splenomegaly Segmentation Network (SS-Net) to introduce the deep convolutional neural network (DCNN) approaches in multi-modal MRI splenomegaly segmentation. Large convolutional kernel layers were used to address the spatial and anatomical variations, while the conditional generative adversarial networks were employed to leverage the segmentation performance of SS-Net in an end-to-end manner. A clinically acquired cohort containing both T1-weighted (T1w) and T2-weighted (T2w) MRI splenomegaly scans was used to train and evaluate the performance of multi-atlas segmentation (MAS), 2D DCNN networks, and a 3-D DCNN network. From the experimental results, the DCNN methods achieved superior performance to the state-of-the-art MAS method. The proposed SS-Net method has achieved the highest median and mean Dice scores among the investigated baseline DCNN methods.

Acceleration of spleen segmentation with end-to-end deep learning method and automated pipeline

Delineation of Computed Tomography (CT) abdominal anatomical structure, specifically spleen segmentation, is useful for not only measuring tissue volume and biomarkers but also for monitoring interventions. Recently, segmentation algorithms using deep learning have been widely used to reduce time humans spend to label CT data. However, the computerized segmentation has two major difficulties: managing intermediate results (e.g., resampled scans, 2D sliced image for deep learning), and setting up the system environments and packages for autonomous execution. To overcome these issues, we propose an automated pipeline for the abdominal spleen segmentation. This pipeline provides an end-to-end synthesized process that allows users to avoid installing any packages and to deal with the intermediate results locally. The pipeline has three major stages: pre-processing of input data, segmentation of spleen using deep learning, 3D reconstruction with the generated labels by matching the segmentation results with the original image dimensions, which can then be used later and for display or demonstration. Given the same volume scan, the approach described here takes about 50 s on average whereas the manual segmentation takes about 30 min on the average. Even if it includes all subsidiary processes such as preprocessing and necessary setups, the whole pipeline process requires on the average 20 min from beginning to end.

Improving Splenomegaly Segmentation by Learning from Heterogeneous Multi-Source Labels

Splenomegaly segmentation on computed tomography (CT) abdomen anatomical scans is essential for identifying spleen biomarkers and has applications for quantitative assessment in patients with liver and spleen disease. Deep convolutional neural network automated segmentation has shown promising performance for splenomegaly segmentation. However, manual labeling of abdominal structures is resource intensive, so the labeled abdominal imaging data are rare resources despite their essential role in algorithm training. Hence, the number of annotated labels (e.g., spleen only) are typically limited with a single study. However, with the development of data sharing techniques, more and more publicly available labeled cohorts are available from different resources. A key new challenging is to co-learn from the multi-source data, even with different numbers of labeled abdominal organs in each study. Thus, it is appealing to design a co-learning strategy to train a deep network from heterogeneously labeled scans. In this paper, we propose a new deep convolutional neural network (DCNN) based method that integrates heterogeneous multi-resource labeled cohorts for splenomegaly segmentation. To enable the proposed approach, a novel loss function is introduced based on the Dice similarity coefficient to adaptively learn multi-organ information from different resources. Three cohorts were employed in our experiments, the first cohort (98 CT scans) has only splenomegaly labels, while the second training cohort (100 CT scans) has 15 distinct anatomical labels with normal spleens. A separate, independent cohort consisting of 19 splenomegaly CT scans with labeled spleen was used as testing cohort. The proposed method achieved the highest median Dice similarity coefficient value (0.94), which is superior (p-value<0.01 against each other method) to the baselines of multi-atlas segmentation (0.86), SS-Net segmentation with only spleen labels (0.90) and U-Net segmentation with multi-organ training (0.91). Our approach for adapting the loss function and training structure is not specific to the abdominal context and may be beneficial in other situations where datasets with varied label sets are available.

Robust Multicontrast MRI Spleen Segmentation for Splenomegaly Using Multi-Atlas Segmentation

OBJECTIVE

Magnetic resonance imaging (MRI) is an essential imaging modality in noninvasive splenomegaly diagnosis. However, it is challenging to achieve spleen volume measurement from three-dimensional MRI given the diverse structural variations of human abdomens as well as the wide variety of clinical MRI acquisition schemes. Multi-atlas segmentation (MAS) approaches have been widely used and validated to handle heterogeneous anatomical scenarios. In this paper, we propose to use MAS for clinical MRI spleen segmentation for splenomegaly.

METHODS

First, an automated segmentation method using the selective and iterative method for performance level estimation (SIMPLE) atlas selection is used to address the concerns of inhomogeneity for clinical splenomegaly MRI. Then, to further control outliers, semiautomated craniocaudal spleen length-based SIMPLE atlas selection (L-SIMPLE) is proposed to integrate a spatial prior in a Bayesian fashion and guide iterative atlas selection. Last, a graph cuts refinement is employed to achieve the final segmentation from the probability maps from MAS.

RESULTS

A clinical cohort of 55 MRI volumes (28 T1 weighted and 27 T2 weighted) was used to evaluate both automated and semiautomated methods.

CONCLUSION

The results demonstrated that both methods achieved median Dice , and outliers were alleviated by the L-SIMPLE (≍1 min manual efforts per scan), which achieved 0.97 Pearson correlation of volume measurements with the manual segmentation.

SIGNIFICANCE

In this paper, spleen segmentation on MRI splenomegaly using MAS has been performed.

SynSeg-Net: Synthetic Segmentation Without Target Modality Ground Truth

A key limitation of deep convolutional neural networks (DCNN) based image segmentation methods is the lack of generalizability. Manually traced training images are typically required when segmenting organs in a new imaging modality or from distinct disease cohort. The manual efforts can be alleviated if the manually traced images in one imaging modality (e.g., MRI) are able to train a segmentation network for another imaging modality (e.g., CT). In this paper, we propose an end-to-end synthetic segmentation network (SynSeg-Net) to train a segmentation network for a target imaging modality without having manual labels. SynSeg-Net is trained by using (1) unpaired intensity images from source and target modalities, and (2) manual labels only from source modality. SynSeg-Net is enabled by the recent advances of cycle generative adversarial networks (CycleGAN) and DCNN. We evaluate the performance of the SynSeg-Net on two experiments: (1) MRI to CT splenomegaly synthetic segmentation for abdominal images, and (2) CT to MRI total intracranial volume synthetic segmentation (TICV) for brain images. The proposed end-to-end approach achieved superior performance to two stage methods. Moreover, the SynSeg-Net achieved comparable performance to the traditional segmentation network using target modality labels in certain scenarios. The source code of SynSeg-Net is publicly available 2.

Randomized, double-blind, phase two study of ruxolitinib plus regorafenib in patients with relapsed/refractory metastatic colorectal cancer

BACKGROUND

The Janus kinase/signal transducer and activator of transcription (JAK-STAT) signaling pathway plays a key role in the systemic inflammatory response in many cancers, including colorectal cancer (CRC). This study evaluated the addition of ruxolitinib, a potent JAK1/2 inhibitor, to regorafenib in patients with relapsed/refractory metastatic CRC.

METHODS

In this two-part, multicenter, phase 2 study, eligible adult patients had metastatic adenocarcinoma of the colon or rectum; an Eastern Cooperative Oncology Group performance status of 0-2; received fluoropyrimidine, oxaliplatin, and irinotecan-based chemotherapy, an anti-vascular endothelial growth factor therapy (if no contraindication); and if KRAS wild-type (and no contraindication), an anti-epidermal growth factor receptor therapy; and progressed following the last administration of approved therapy. Patients who received previous treatment with regorafenib, had an established cardiac or gastrointestinal disease, or had an active infection requiring treatment were excluded. The study was conducted in 95 sites in North America, European Union, Asia Pacific, and Israel. After an open-label, safety run-in phase (part 1; ruxolitinib 20 mg twice daily [BID] plus regorafenib 160 mg once daily [QD]), the double-blind, randomized phase (part 2) was conducted wherein patients were randomized 1:1 to receive ruxolitinib 15 mg BID plus regorafenib 160 mg QD [ruxolitinib group] or placebo plus regorafenib 160 mg QD [placebo group]. Part 2 included substudy 1 (patients with high systemic inflammation, ie, C-reactive protein [CRP] >10 mg/L) and substudy 2 (patients with low systemic inflammation, ie, CRP ≤10 mg/L); the primary endpoint was overall survival (OS).

RESULTS

The study was terminated early; substudy 1 was terminated for futility at interim analysis and substudy 2 was terminated per sponsor decision. Ruxolitinib 20 mg BID was well tolerated in the safety run-in (n = 11). Overall, 396 patients were randomized (substudy 1: n = 175 [ruxolitinib group, n = 87; placebo group, n = 88]; substudy 2: n = 221 [ruxolitinib group, n = 110; placebo group, n = 111]). There was no significant difference in OS or progression-free survival (PFS) between treatments in substudy 1 (OS: hazard ratio [HR] = 1.040 [95% confidence interval: 0.725-1.492]; PFS: HR = 1.004 [0.724-1.391]) and substudy 2 (OS: HR = 0.767 [0.478-1.231]; PFS: HR = 0.787 [0.576-1.074]). The most common hematologic adverse event was anemia. No new safety signals with ruxolitinib were identified.

CONCLUSIONS

Although addition of ruxolitinib to regorafenib did not show increased safety concerns in patients with relapsed/refractory metastatic CRC, this combination did not improve OS/PFS vs. regorafenib plus placebo.

A Phase Ib/II Study of the JAK1 Inhibitor, Itacitinib, plus nab-Paclitaxel and Gemcitabine in Advanced Solid Tumors

Lessons Learned.

Itacitinib in combination with nab‐paclitaxel plus gemcitabine demonstrated an acceptable safety profile with clinical activity in patients with advanced solid tumors including pancreatic cancer.

The results support future studies of itacitinib as a component of combination regimens with other immunologic and targeted small molecule anticancer agents.

Background.

Cytokine‐mediated signaling via JAK/STAT is central to tumor growth, survival, and systemic inflammation, which is associated with cancer cachexia, particularly in pancreatic cancer. Because of their centrality in the pathogenesis of cancer cachexia and progression, JAK isozymes have emerged as promising therapeutic targets. Preclinical studies have demonstrated antiproliferative effects of JAK/STAT pathway inhibition in both in vitro and in vivo models of cancer, including pancreatic cancer.

Methods.

This phase Ib/II dose‐optimization study assessed itacitinib, a selective JAK1 inhibitor, combined with nab‐paclitaxel plus gemcitabine in adults with treatment‐naïve advanced/metastatic disease (Part 1) or pancreatic adenocarcinoma (Parts 2/2A; NCT01858883). Starting doses (Part 1) were itacitinib 400 mg, nab‐paclitaxel 125 mg/m², and gemcitabine 1,000 mg/m². Additional dose levels incorporated were granulocyte colony‐stimulating factor, de‐escalations of itacitinib to 300 mg once daily (QD), nab‐paclitaxel to 100 mg/m², and gemcitabine to 750 mg/m².

Results.

Among 55 patients in Part 1, 6 developed seven hematologic dose‐limiting toxicities (Cycle 1). Itacitinib 300 mg plus nab‐paclitaxel 125 mg/m² and gemcitabine 1,000 mg/m² was tolerated and expanded in Part 2. Treatment discontinuation and grade 3/4 neutropenia rates prompted itacitinib de‐escalation to 200 mg QD in Part 2A. The most common grade 3/4 toxicities were fatigue and neutropenia. Partial responses occurred across all itacitinib doses and several tumor types (overall response rate, 24%).

Conclusion.

Itacitinib plus chemotherapy demonstrated acceptable safety and clinical activity in patients with advanced solid tumors including pancreatic cancers. This study was terminated early (sponsor's decision) based on negative phase III results for a JAK1/2 inhibitor in previously treated advanced pancreatic cancer.

A Phase Ib study of ruxolitinib + gemcitabine ± nab-paclitaxel in patients with advanced solid tumors

Purpose

Aberrant activation of the Janus-associated kinase (JAK)/signal transducer and activator of transcription (STAT) pathway is associated with increased malignant cell proliferation and survival. This Phase Ib study evaluated ruxolitinib, a potent JAK1/2 inhibitor, in combination with gemcitabine with or without nab-paclitaxel in patients with advanced solid tumors.

Patients and methods

Patients received ruxolitinib + gemcitabine (regimen A) or ruxolitinib + gemcitabine + nab-paclitaxel (regimen B). The objective of the dose-finding phase was to identify the maximum tolerated doses (MTDs) of ruxolitinib plus gemcitabine with or without nab-paclitaxel.

Results

Among 42 patients enrolled, the median age was 62.5 years, 81.0% had pancreatic cancer, and almost 62% had received prior systemic therapy. Regimen A was tolerated with standard doses of gemcitabine; regimen B was tolerated with reduced doses of gemcitabine/nab-paclitaxel or concomitant granulocyte colony-stimulating factor. The sponsor decided to terminate the study early due to the interim analysis results of the Phase III JANUS 1 study. Discontinuations were mainly due to radiologic or clinical disease progression (81.0% of patients). Median treatment durations were 55.5 days (cohort A0) and 150.5 days (pooled B cohorts). Four patients (pooled B cohorts) had dose-limiting toxicities: grade 3 pneumonia (n=1), grade 4 neutropenia (n=1), and grade 4 thrombocytopenia (n=2). The most common grade 3/4 hematologic adverse events (AEs) were anemia, thrombocytopenia, and neutropenia. Serious AEs occurring in ≥2 patients in cohort A0 or pooled B cohorts were abdominal pain, sepsis (cohort A0), dehydration, anemia, and asthenia (pooled B cohorts). Overall response rates (ORRs) were 12.5% in cohort A0 and 38.5% in pooled B cohorts. Among patients with pancreatic cancer, ORR was 23.5% (14.0% cohort A0 30.0% pooled B cohorts).

Conclusion

The study was terminated early prior to reaching MTDs per sponsor decision; although ruxolitinib plus gemcitabine with or without nab-paclitaxel was generally safe and well tolerated in patients with advanced solid tumors, this combination will not be pursued further.

Fully Convolutional Neural Networks Improve Abdominal Organ Segmentation

Abdominal image segmentation is a challenging, yet important clinical problem. Variations in body size, position, and relative organ positions greatly complicate the segmentation process. Historically, multi-atlas methods have achieved leading results across imaging modalities and anatomical targets. However, deep learning is rapidly overtaking classical approaches for image segmentation. Recently, Zhou et al. showed that fully convolutional networks produce excellent results in abdominal organ segmentation of computed tomography (CT) scans. Yet, deep learning approaches have not been applied to whole abdomen magnetic resonance imaging (MRI) segmentation. Herein, we evaluate the applicability of an existing fully convolutional neural network (FCNN) designed for CT imaging to segment abdominal organs on T2 weighted (T2w) MRI's with two examples. In the primary example, we compare a classical multi-atlas approach with FCNN on forty-five T2w MRI's acquired from splenomegaly patients with five organs labeled (liver, spleen, left kidney, right kidney, and stomach). Thirty-six images were used for training while nine were used for testing. The FCNN resulted in a Dice similarity coefficient (DSC) of 0.930 in spleens, 0.730 in left kidneys, 0.780 in right kidneys, 0.913 in livers, and 0.556 in stomachs. The performance measures for livers, spleens, right kidneys, and stomachs were significantly better than multi-atlas (p < 0.05, Wilcoxon rank-sum test). In a secondary example, we compare the multi-atlas approach with FCNN on 138 distinct T2w MRI's with manually labeled pancreases (one label). On the pancreas dataset, the FCNN resulted in a median DSC of 0.691 in pancreases versus 0.287 for multi-atlas. The results are highly promising given relatively limited training data and without specific training of the FCNN model and illustrate the potential of deep learning approaches to transcend imaging modalities.

Splenomegaly Segmentation using Global Convolutional Kernels and Conditional Generative Adversarial Networks

Spleen volume estimation using automated image segmentation technique may be used to detect splenomegaly (abnormally enlarged spleen) on Magnetic Resonance Imaging (MRI) scans. In recent years, Deep Convolutional Neural Networks (DCNN) segmentation methods have demonstrated advantages for abdominal organ segmentation. However, variations in both size and shape of the spleen on MRI images may result in large false positive and false negative labeling when deploying DCNN based methods. In this paper, we propose the Splenomegaly Segmentation Network (SSNet) to address spatial variations when segmenting extraordinarily large spleens. SSNet was designed based on the framework of image-to-image conditional generative adversarial networks (cGAN). Specifically, the Global Convolutional Network (GCN) was used as the generator to reduce false negatives, while the Markovian discriminator (PatchGAN) was used to alleviate false positives. A cohort of clinically acquired 3D MRI scans (both T1 weighted and T2 weighted) from patients with splenomegaly were used to train and test the networks. The experimental results demonstrated that a mean Dice coefficient of 0.9260 and a median Dice coefficient of 0.9262 using SSNet on independently tested MRI volumes of patients with splenomegaly.

Multi-atlas Segmentation Enables Robust Multi-contrast MRI Spleen Segmentation for Splenomegaly

Non-invasive spleen volume estimation is essential in detecting splenomegaly. Magnetic resonance imaging (MRI) has been used to facilitate splenomegaly diagnosis in vivo. However, achieving accurate spleen volume estimation from MR images is challenging given the great inter-subject variance of human abdomens and wide variety of clinical images/modalities. Multi-atlas segmentation has been shown to be a promising approach to handle heterogeneous data and difficult anatomical scenarios. In this paper, we propose to use multi-atlas segmentation frameworks for MRI spleen segmentation for splenomegaly. To the best of our knowledge, this is the first work that integrates multi-atlas segmentation for splenomegaly as seen on MRI. To address the particular concerns of spleen MRI, automated and novel semi-automated atlas selection approaches are introduced. The automated approach interactively selects a subset of atlases using selective and iterative method for performance level estimation (SIMPLE) approach. To further control the outliers, semi-automated craniocaudal length based SIMPLE atlas selection (L-SIMPLE) is proposed to introduce a spatial prior in a fashion to guide the iterative atlas selection. A dataset from a clinical trial containing 55 MRI volumes (28 T1 weighted and 27 T2 weighted) was used to evaluate different methods. Both automated and semi-automated methods achieved median DSC > 0.9. The outliers were alleviated by the L-SIMPLE (≈1 min manual efforts per scan), which achieved 0.9713 Pearson correlation compared with the manual segmentation. The results demonstrated that the multi-atlas segmentation is able to achieve accurate spleen segmentation from the multi-contrast splenomegaly MRI scans.

Multi-Atlas Spleen Segmentation on CT Using Adaptive Context Learning

Automatic spleen segmentation on CT is challenging due to the complexity of abdominal structures. Multi-atlas segmentation (MAS) has shown to be a promising approach to conduct spleen segmentation. To deal with the substantial registration errors between the heterogeneous abdominal CT images, the context learning method for performance level estimation (CLSIMPLE) method was previously proposed. The context learning method generates a probability map for a target image using a Gaussian mixture model (GMM) as the prior in a Bayesian framework. However, the CLSSIMPLE typically trains a single GMM from the entire heterogeneous training atlas set. Therefore, the estimated spatial prior maps might not represent specific target images accurately. Rather than using all training atlases, we propose an adaptive GMM based context learning technique (AGMMCL) to train the GMM adaptively using subsets of the training data with the subsets tailored for different target images. Training sets are selected adaptively based on the similarity between atlases and the target images using cranio-caudal length, which is derived manually from the target image. To validate the proposed method, a heterogeneous dataset with a large variation of spleen sizes (100 cc to 9000 cc) is used. We designate a metric of size to differentiate each group of spleens, with 0 to 100 cc as small, 200 to 500cc as medium, 500 to 1000 cc as large, 1000 to 2000 cc as XL, and 2000 and above as XXL. From the results, AGMMCL leads to more accurate spleen segmentations by training GMMs adaptively for different target images.

Efficacy/safety analysis of a phase 2 study of ruxolitinib (Rux) + regorafenib (Re) in patients (pts) with relapsed/refractory (r/r) metastatic colorectal cancer (mCRC)

663

Background: The JAK-STAT pathway plays a role in the systemic inflammatory response in CRC. Rux, a potent JAK1/2 inhibitor, was evaluated in r/r mCRC pts. Methods: After a safety run-in (Rux 20 mg BID + Re 160 mg QD), pts were randomized to Rux 15 mg BID or placebo (Pb) + Re 160 mg QD. Rux could be titrated to 20 mg BID. The randomized phase included Substudy 1 (S1, pts with C-reactive protein [CRP] > 10 mg/L) and Substudy 2 (S2, pts with CRP ≤ 10 mg/L). Primary endpoint: OS. Results: Rux 20 mg BID was well tolerated in the safety run-in (n = 11). 396 pts were randomized (S1: n = 175; S2: n = 221). Median age in Rux vs (v) Pb groups: 62 v 60 yr (S1), 59 v 61 yr (S2). Most pts had ≥ 3 prior chemotherapy regimens: 85% v 84% (S1); 81% v 78% (S2). Median treatment durations: 57 d with Rux v 56 d with Pb (S1), 106 d with Rux v 56 d with Pb (S2). Discontinuations were mainly due to disease progression (S1: 61% v 63%, S2: 62% v 66%) or AEs (S1: 10% v 19%, S2: 9% v 9%). Rux + Re did not improve OS/PFS over Re + Pb in S1/S2 (see Table). S1 was terminated for futility at interim analysis; S2 was terminated per sponsor decision. The number of events required for final efficacy analysis was reached in S1, not in S2. Most common non-hematologic AEs (Rux v Pb): palmar-plantar erythrodysesthesia syndrome (PPES; S1: 42% v 44%; S2: 58% v 47%), diarrhea (S1: 38% v 31%; S2: 39% v 27%), decreased appetite (S1: 37% v 36%; S2: 26% v 33%), fatigue (S1: 34% v 36%; S2: 41% v 44%), hypertension (S1: 21% v 26%; S2: 42% v 40%). Most common grade (G) 3/4 non-hematologic AEs: PPES (S1: 13% v 15%; S2: 17% v 13%) and hypertension (S1: 9% v 7%; S2: 22% v 16%). Most common G 3/4 hematologic AEs (new/worsening lab abnormalities): lymphopenia (S1: 13% v 8%; S2: 14% v 7%) and anemia (S1: 4% v 5%; S2: 9% v 4%). Conclusions: Rux + Re did not improve OS/PFS in mCRC pts over Re alone. There was a nonsignificant trend towards improved OS/PFS in S2. Rux 15-20 mg BID safety profile was consistent with previous studies in other tumors. Clinical trial information: NCT02119676. [Table: see text]

A phase 1b/2 study of INCB039110 + nab-paclitaxel (N) and gemcitabine (G) in patients (pts) with advanced solid tumors and pancreatic cancer (PC)

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Background: JAK-STAT activity has been associated with malignant cell proliferation and production of proinflammatory cytokines involved in cancer progression. INCB039110 is a potent and selective inhibitor of JAK1. Methods: This was a 2-part phase 1b/2 open-label study evaluating INCB039110 (300 or 400 mg QD) in combination with N and G in pts with advanced or metastatic solid tumors (Part 1 [P1], dose optimization phase) and pts with advanced or metastatic PC who had not received prior chemotherapy (Part 2 [P2] and 2A [P2A]). Pts in P2 received the MTD established in P1: INCB039110 (300 mg QD) + N (125 mg/m2 day [d] 1, 8, 15) + G (1000 mg/m2 d 1, 8, 15), 28-d cycle. For exploratory purposes, pts in P2A underwent a 7-d induction phase with INCB039110 (200 mg QD) before receiving INCB039110 (200 mg QD) + N (125 mg/m2 d 1, 8, 15) + G (1000 mg/m2d 1, 8, 15). The primary objective was to evaluate safety/tolerability. Results: 55 pts were enrolled (27 P1, 20 P2, and 8 P2A). Most patients had advanced PC (n = 46). Median age was 65 (P1), 67 (P2), and 66 years (P2A). Prior therapy: 67% in P1, 30% in P2, and 0% in P2A. The most common reasons for treatment discontinuation were adverse events (AEs; 41% P1, 20% P2, 38% P2A), disease progression (37% P1, 45% P2, 0% P2A), and study termination by the sponsor (0% P1, 0% P2, 38% P2A). Median treatment durations were 84 d (P1), 121 d (P2), and 47 d (P2A). The most common non-hematologic AEs (all grades) were fatigue (59% P1, 75% P2, 88% P2A), nausea (41% P1, 50% P2, 38% P2A), pyrexia (37% P1, 40% P2, 13% P2A), and peripheral edema (30% P1, 50% P2, 25% P2A), with few grade 3 or 4 non-hematologic AEs. The most common grade 3 or 4 hematologic AEs (laboratory values) were neutropenia (33% P1, 60% P2, 13% P2A), lymphopenia (30% P1, 30% P2, 13% P2A), and leukopenia (30% P1, 45% P2, 0% P2A). The most common serious AEs occurring in ≥ 3 pts were pneumonia (n = 4 P1, n = 2 P2, n = 0 P2A) and anemia (n = 3 P1, n = 2 P2, n = 2 P2A). Among evaluable patients, ORR (all PRs) and DCR were 27% (13/48) and 75% (36/48), respectively. Responses were seen across INCB039110 doses. Conclusions: INCB039110 + N/G showed an acceptable safety profile in pts with advanced PC, with the combination demonstrating clinical activity. Clinical trial information: NCT01858883.

Primary analysis of a phase II open-label trial of INCB039110, a selective JAK1 inhibitor, in patients with myelofibrosis

Combined Janus kinase 1 (JAK1) and JAK2 inhibition therapy effectively reduces splenomegaly and symptom burden related to myelofibrosis but is associated with dose-dependent anemia and thrombocytopenia. In this open-label phase II study, we evaluated the efficacy and safety of three dose levels of INCB039110, a potent and selective oral JAK1 inhibitor, in patients with intermediate- or high-risk myelofibrosis and a platelet count ≥50×10⁹/L. Of 10, 45, and 32 patients enrolled in the 100 mg twice-daily, 200 mg twice-daily, and 600 mg once-daily cohorts, respectively, 50.0%, 64.4%, and 68.8% completed week 24. A ≥50% reduction in total symptom score was achieved by 35.7% and 28.6% of patients in the 200 mg twice-daily cohort and 32.3% and 35.5% in the 600 mg once-daily cohort at week 12 (primary end point) and 24, respectively. By contrast, two patients (20%) in the 100 mg twice-daily cohort had ≥50% total symptom score reduction at weeks 12 and 24. For the 200 mg twice-daily and 600 mg once-daily cohorts, the median spleen volume reductions at week 12 were 14.2% and 17.4%, respectively. Furthermore, 21/39 (53.8%) patients who required red blood cell transfusions during the 12 weeks preceding treatment initiation achieved a ≥50% reduction in the number of red blood cell units transfused during study weeks 1-24. Only one patient discontinued for grade 3 thrombocytopenia. Non-hematologic adverse events were largely grade 1 or 2; the most common was fatigue. Treatment with INCB039110 resulted in clinically meaningful symptom relief, modest spleen volume reduction, and limited myelosuppression.

Phase I/II Study of an Anti-CD30 Monoclonal Antibody (MDX-060) in Hodgkin's Lymphoma and Anaplastic Large-Cell Lymphoma

Purpose

MDX-060 is a human anti-CD30 immunoglobulin (Ig) G1κ monoclonal antibody that inhibits growth of CD30-expressing tumor cells in preclinical models. To determine the safety, maximum-tolerated dose (MTD), and efficacy of MDX-060 in patients with relapsed or refractory CD30+ lymphomas, sequential phase I and II studies were performed.

Patients and Methods

In the phase I portion, MDX-060 was administered intravenously at doses of 0.1, 1, 5, or 10 mg/kg weekly for 4 weeks to cohorts of three to six patients. Twenty-one patients—16 with Hodgkin's lymphoma (HL), three with anaplastic large-cell lymphoma (ALCL), and two with CD30+ T-cell lymphoma—were enrolled. Because of the lack of a defined MTD or dose-response correlation, the phase II portion was amended to include several dose levels. In the phase II portion, an additional 51 patients, 47 with HL and four with ALCL, were treated at doses of 1, 5, 10, and 15 mg/kg.

Results

MDX-060 was well tolerated, and an MTD has not been identified. Only 7% of patients experienced grade 3 or 4 treatment-related adverse events. Among the 72 patients treated, clinical responses were observed in six. Twenty-five patients had stable disease, including five who remained free from progression 1 year after treatment.

Conclusion

MDX-060 was well tolerated at doses up to 15 mg/kg. MDX-060 has limited activity as a single agent, but the minimal toxicity observed and the significant proportion of patients with stable disease suggests that further study of MDX-060 in combination with other therapies is warranted.

Overexpression of a member of the pentraxin family (PTX3) in human soft tissue liposarcoma

A unique feature of human soft tissue liposarcoma is a stable (12;16)(q13;p11) translocation observed mainly in myxoid and roundcell liposarcomas. This translocation results in FUS/CHOP fusion transcripts with a corresponding oncogenic protein. We hypothesised that genes downstream of FUS/CHOP might serve as attractive candidates for novel tumour associated antigens. Among a panel of analysed genes, only pentraxin related gene (PTX3) demonstrated high expression in liposarcomas as compared to normal tissues. The analysis of RNA and protein expression demonstrated concordant results. However, the level of RNA and protein overexpression did not correlate in all cases. Finally, PTX3 expression was not related to presence of a FUS/CHOP fusion transcript within the liposarcoma tissues. PTX3 has been associated with adipocyte differentiation and now, additionally, is characterised by a markedly increased expression in human soft tissue liposarcoma. This finding mandates further research efforts to clarify the exact role of PTX3 in liposarcoma oncogenesis.

The human oculomotor response to simultaneous visual and physical movements at two different frequencies

In order to investigate interactions in the visual and vestibular systems' oculomotor response to linear movement, we developed a two-frequency stimulation technique. Thirteen subjects lay on their backs and were oscillated sinusoidally along their z-axes at between 0.31 and 0.81 Hz. During the oscillation subjects viewed a large, high-contrast, visual pattern oscillating in the same direction as the physical motion but at a different, non-harmonically related frequency. The evoked eye movements were measured by video-oculography and spectrally analysed. We found significant signal level at the sum and difference frequencies as well as at other frequencies not present in either stimulus. The emergence of new frequencies indicates non-linear processing consistent with an agreement-detector system that have previously proposed.

The human oculomotor response to simultaneous visual and physical movements at two different frequencies

In order to investigate interactions in the visual and vestibular systems' oculomotor response to linear movement, we developed a two-frequency stimulation technique. Thirteen subjects lay on their backs and were oscillated sinusoidally along their z-axes at between 0.31 and 0.81 Hz. During the oscillation subjects viewed a large, high-contrast, visual pattern oscillating in the same direction as the physical motion but at a different, non-harmonically related frequency. The evoked eye movements were measured by video-oculography and spectrally analysed. We found significant signal level at the sum and difference frequencies as well as at other frequencies not present in either stimulus. The emergence of new frequencies indicates non-linear processing consistent with an agreement-detector system that have previously proposed.

Inhibitory action of orotate, 2-thioorotate and isoorotate on nucleotide metabolism and nucleic acid synthesis in hepatoma cells

1. The specificity of the action of orotate on hepatoma cells was investigated. 2. Orotic acid and its methyl ester had similar inhibitory effects on the incorporation of [3H]thymidine into DNA of hepatoma cells. 3. In contrast to previous studies in vivo, incubation of rat kidney cells with orotate caused an increase in the ratio of UTP/ATP concentrations that was similar to effects on hepatic cells. 4. Inhibitory effects of 2-thioorotate and isoorotate on metabolism were found to be less selective and required higher concentrations than with orotate.

Digital image analysis of optic nerve head pallor as a diagnostic test for early glaucoma

We developed a computer-based technique to quantify optic nerve head pallor from videographically acquired digitized optic nerve images and tested the ability of pallor measurements to discriminate between normal eyes and eyes with early glaucoma. Corresponding pixel values from images obtained under 540 nm (green) and 640 nm (red) light with a videographic fundus camera were used to quantify optic nerve head pallor. A pallor density histogram was calculated for each eye, and contained values between 0 (red) to 1 (white). A measure of the distribution width of the histogram provided pallor measurements standardized to the measurements of the large veins of the disc. A database of one eye each of 44 normal controls and 70 patients with early open angle glaucoma was used to test the measurements for diagnostic sensitivity and specificity. These standardized pallor measurements did not perform better than absolute pallor measurements to discriminate between normal and glaucomatous eyes. The sensitivity and specificity of standardized pallor measurements (49% and 57%, respectively, for this database) were not as good as those for stereoscopic measurements of disc rim area in the same database (70% and 73%). Pallor measurements of this type do not appear to be sensitive or specific indicators of early glaucoma.

Inhibitory effects of orotate on precursor incorporation into nucleic acids

The influence of orotic acid on the incorporation of precursors into nucleic acids was studied in mice and rats and in isolated cells. In vivo, orotate levels were modified by two diets which are known to increase the rate of pyrimidine nucleotide synthesis in rat liver. Of these diets, a 1% orotate diet had greater inhibitory effects than an arginine-deficient diet on the incorporation of [3H]orotate into RNA of mouse kidney than mouse liver. This contrasted with the situation in the rat where there was a greater effect in the liver than the kidney. The situation in the rat was more readily interpreted than in the mouse in terms of previously established effects of these diets on ribonucleotide pool sizes. However, studies using [3H]adenosine as a precursor for incorporation into RNA suggested that even in the mouse the effects of orotate were on pool sizes rather than an inhibitory effect on RNA synthesis. The incorporation of [3H]thymidine into DNA was inhibited by orotate to a similar degree in cultured HTC hepatoma cells and a line of rat liver epithelial cells. An effect on DNA synthesis rather than solely on pool sizes was suggested by the observation that the pool size of dTTP was not increased by 5 mM orotate under conditions in which there was a four-fold increase in the level of UTP in HTC cells. An inhibitory effect of orotate on DNA synthesis was further supported by an observation of decreased incorporation of [3H]deoxyadenosine into DNA and a lower rate of cellular proliferation.