74P Spatial concordance of tumor proliferation and accelerated repopulation from pathologic images to 18F-FLT PET images: A basic study guided for PET-based radiotherapy dose painting

e23100 Background: PET imaging with 18F-fluorothymidine (18F-FLT) can potentially be used to identify tumor subvolumes for selecting dose escalation in radiation therapy. The aim of this study was to monitor tumor cell proliferation and repopulation during fractionated radiotherapy and investigated the spatial concordance of tumor cell proliferation and repopulation with 18F-FLT tracer uptake. Methods: Mice bearing A549 xenograft tumors were assigned to 5 different irradiated groups (3f/6d, 6f/12d, 9f/18d, 12f/24d and 18f/36d) with 2 Gy/fractions and non-irradiated group. Serial 18F-FLT micro PET scans were performed at different time points, the maximum of standard uptake value (SUVmax) were measured to detect the feasible time of tumor repopulation during irradiation. Ex vivo images of the spatial pattern of intratumor 18F-FLT uptake and Ki-67 labeling index (LI) were obtained from thin tumor tissue sections. A layer-by-layer comparison between SUVmax and Ki-67 LI results, including the thresholds at which maximum overlap occurred between FLT-segmented areas and areas of active cell proliferation, were conducted to evaluate the spatial imaging pathology correlation. Results: The SUVmax were observed decreases in the 3f/6d group (P = 0.000), compared to these for non-irradiated tumors. However, it was significantly increased in the 6f/12d later, and then gradually reduced with treatment time prolonged again after 6f/12d group. Proliferation changes on pathology imaging at 6f/12d were also confirmed. Significant correlations were found between the SUVmax and Ki-67 LI of all ROIs in each in vitro tumor of cell proliferation group (Ps < 0.001). Similar results were also found in each tumor of accelerated repopulation group (Ps < 0.001). Furthermore, both of the mean ORRs were more than 50% in all layer of the tumor cell proliferation and accelerated groups. Regions of high-intensity 18F-FLT uptake in the autoradiographs exhibited prominent staining for Ki-67. Conclusions: 18F-FLT PET may be a promising imaging surrogate of tumor proliferative response to fractionated radiotherapy and might help make adaptive radiation oncology treatment plan.

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Robust maximization of tumor control probability for radicality constrained radiotherapy dose painting by numbers of head and neck cancer

Physics and Imaging in Radiation Oncology ◽

10.1016/j.phro.2019.11.004 ◽

2019 ◽

Vol 12 ◽

pp. 56-62

Author(s):

Eric Grönlund ◽

Erik Almhagen ◽

Silvia Johansson ◽

Erik Traneus ◽

Anders Ahnesjö

Keyword(s):

Head And Neck Cancer ◽

Head And Neck ◽

Neck Cancer ◽

Tumor Control ◽

Tumor Control Probability ◽

Dose Painting ◽

Radiotherapy Dose

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Phase I study of pazopanib (PAZ) in combination with PCI-24781 (PCI) in patients (pts) with metastatic solid tumors with new tumor proliferation imaging correlates in renal cell carcinoma (RCC) and sarcoma.

Journal of Clinical Oncology ◽

10.1200/jco.2013.31.15_suppl.tps2623 ◽

2013 ◽

Vol 31 (15_suppl) ◽

pp. TPS2623-TPS2623

Author(s):

Thach-Giao Truong ◽

Jennifer A. Grabowsky ◽

Stephanie Chen ◽

Roth Ea ◽

Andrew H. Ko ◽

...

Keyword(s):

Clinical Trial ◽

Phase I ◽

Solid Tumors ◽

Phase Iii ◽

Current Status ◽

Thymidine Uptake ◽

Tumor Proliferation ◽

Phase Ib ◽

Flt Pet ◽

Expansion Cohort

TPS2623 Background: PAZ is a multi-targeted tyrosine kinase inhibitor of VEGFR, PDGFR, and C-KIT, approved for metastatic RCC and refractory sarcoma based on phase III data showing prolonged PFS (JCO 2010;28:1061-8 and Lancet 2012;379:1879-86). PCI is a potent pan-HDAC inhibitor (pan-HDACi), observed in cell lines to change regulation of genes involved in cell signaling, apoptosis, proliferation, differentiation, and angiogenesis (Anticancer Res 2011;31:1115-23). Pre-clinical models suggest epigenetic modification with an HDACi potentiates PAZ’s efficacy by causing chromatin instability and gene expression changes involved in drug resistance (Can Res 2005;65:3815-22 and BJC 2009;100:758-63). We therefore designed a Phase Ia/b clinical trial combining PCI with PAZ in pts with advanced solid tumors, with an expansion cohort for preliminary efficacy in RCC and sarcoma. Methods: Primary objective of this phase Ia/b study is to evaluate the safety and tolerability of the combination of PAZ and PCI to determine the MTD and RP2D. In phase Ia, we utilized an accelerated phase I design. The phase Ib portion will include up to 20 pts per expansion cohort, for up to 32-70 pts enrolled. In phase 1a, pts receive run-in PCI alone on C1D-7 to D-4. Starting with C1D1, pts receive oral PCI on D1-5, 8-12, 15-19 BID 4 hrs apart and PAZ daily (D1-28) q28D cycle. CORRELATIVES: Pre- and post-treatment (Tx) H3 & H4 acetylation and HDAC activity in PBMCs. In phase Ib, these will also be studied in tumor biopsies. We will measure expression of VEGF, VEGFR, RAD51, HIF, Ki67; and analyze SNPs through genomic profiling. We will correlate response with pre- and post-Tx tumor thymidine uptake using 18F-fluorothymidine (FLT-PET) PET. Current Status: This is the 1st trial exploring the combination of an HDACi with PAZ in RCC and sarcoma, where there is an unmet need for new tolerable therapies. It will study FLT-PET, an imaging correlate that captures tumor proliferation and may have a role as a predictive biomarker. We are currently in phase Ia. Enrollment in the 3rd cohort exploring higher doses of PAZ will begin in Feb 2013. Clinical trial information: NCT01543763.

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Pharmacodynamic phase I study using FLT PET/CT in advanced solid malignancies treated with a sequential combination of X-82 and docetaxel.

Journal of Clinical Oncology ◽

10.1200/jco.2017.35.15_suppl.e14088 ◽

2017 ◽

Vol 35 (15_suppl) ◽

pp. e14088-e14088

Author(s):

Gil Edward Harmon ◽

Murtuza M. Rampurwala ◽

Matt Scarpelli ◽

Jens C. Eickhoff ◽

Lakeesha Carmichael ◽

...

Keyword(s):

Day Treatment ◽

Vascular Complications ◽

Therapeutic Window ◽

Tumor Proliferation ◽

Angiogenic Therapy ◽

Flt Pet ◽

Pet Ct ◽

Medicine Physician ◽

Sequential Combination ◽

The Mean

e14088 Background: Increased tumor proliferation has been observed during withdrawal of anti-angiogenic therapy, known as withdrawal flare, which has been demonstrated using [18-F] fluorothymidine [FLT] PET/CT . Sequencing chemotherapy may increase therapeutic window by better synchronizing treatment with tumor proliferation during the flare. This study utilizes FLT PET/CT to assess X-82, a novel VEGFR TKI, used in sequence with docetaxel. Methods: Pts with at least 1 lesion evaluable with FLT PET/CT underwent 21-day treatment cycles with X-82 daily on days 2-15. Starting in cycle 2 (C2), docetaxel was given on day 1 of each cycle. FLT PET/CTs were obtained on days 1 and 15 in cycles 1 and 2. Tumors were identified by a nuclear medicine physician and manually segmented. The maximum tumor FLT uptake SUVmax and the total tumor FLT uptake SUVtotal were extracted for each tumor. To quantify changes in tumor FLT uptake, SUVs were log transformed and included in mixed effects models with random effects accounting for intrapatient correlation of tumor responses. Results: 14 pts were treated with median 3.5 cycles (range 0-12). 4 pts with 13 metastatic tumors completed all PET scans and were included in the pharmacodynamic assessment. 1 pt had an unconfirmed PR and 7 pts had stable disease per RECIST 1.1. The mean percent (%) change in tumor SUV during C1 (X-82 monotherapy) was -13% for SUVmax (P = 0.04) and -17% for SUVtotal (P = 0.14). The mean % change in tumor SUV during C2 (X-82 + docetaxel) was -44% for SUVmax (P = 0.03) and -59% for SUVtotal (P < 0.01). There was a significantly greater decrease in SUV in C2 than in C1 for both SUVmax (P = 0.03) and SUVtotal(P = 0.02). Ten grade 3 AEs possibly related to X-82 were noted in 6 pts, including infections, cytopenias, and vascular complications. Conclusions: Diminished tumor proliferation was observed during X-82 treatment, indicating successful targeting of VEGFRs. Sequential combination of X-82 plus docetaxel showed greater decreases in tumor proliferation compared to X-82 monotherapy indicating value in sequencing chemotherapy during VEGFR TKI treatment breaks. There is evidence that combination therapy is both safe and effective. Clinical trial information: NCT 02146222.

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