3'-Deoxy-3'-18F-Fluorothymidine and 18F-Fluorodeoxyglucose positron emission tomography for the early prediction of response to Regorafenib in patients with metastatic colorectal cancer refractory to all standard therapies.

PURPOSE: The purpose of this study was to evaluate the value of 3'-deoxy-3'-18F-fluorothymidine (18F-FLT) and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) for early prediction of standard anatomic response and survival outcomes in patients with metastatic colorectal cancer (mCRC) receiving Regorafenib. METHODS: Sixty-eight patients with mCRC refractory to standard cytotoxic chemotherapy were enrolled and received Regorafenib (160 mg/day on days 1-21, following a 7-day break). Standard anatomical response was evaluated every 8 weeks. Both scans were performed before and on day 21 of Regorafenib. RESULTS: Of the 61 patients included in per-protocol analysis, complete response was not observed, but partial response was observed in 8.2% (n = 5), stable disease in 67.2% (n = 41), and progressive disease in 24.6% (n = 15). The objective response rate was 8.2% and disease control rate 75.4%. Five responders (8.2%) and 13 non-responders (21.3%) met the CT and 18F-FLT PET/CT criteria (maximum standardized uptake value decrease ≥ 10.6% for responders). Forty-three (70.5%) exhibited discordant responses on CT and 18F-FLT PET/CT (McNemar test, P < 0.001). At a median follow-up of 8.9 months, median progression-free survival (PFS) and median overall survival (OS) were 3.6 months (95% confidence interval [CI], 3.34-3.80 months) and 8.5 months (95% CI, 6.95-10.10 months), respectively. Comparison of PFS and OS according to 18F-FLT PET/CT response revealed slightly longer PFS (P = 0.015) in responders, but the correlation with OS was not significant. The PET Response Criteria in Solid Tumours (PERCIST) of 18F-FDG PET/CT revealed differences in PFS and OS between partial metabolic response (PMR) and non-PMR (P = 0.048 and P = 0.014, respectively), and between progressive metabolic disease (PMD) and non-PMD (P = 0.189 and P = 0.007, respectively). CONCLUSIONS: Survival outcome was significantly associated with PERCIST using 18F-FDG PET/CT but the change of 18F-FLT uptake was only slightly associated with PFS. 18F-FDG PET/CT can be used as imaging biomarker to predict clinical outcomes early in patients with mCRC receiving Regorafenib.

High-yielding, automated production of 3'-deoxy-3'-[(18)F]fluorothymidine using a modified Bioscan Coincidence FDG reaction module.

INTRODUCTION: High-yielding, automated production of a PET tracer that reflects proliferation, 3'-deoxy-3'-[(18)F]fluorothymidine ([(18)F]FLT), is reported using a modified Bioscan Coincidence FDG reaction module. METHODS: Production of [(18)F]FLT was implemented through: (1) modification of an original FDG manifold; (2) application of an alternate time sequence; and (3) altered solid-phase extraction (SPE) purification. Quality control testing, including standard radiochemical figures of merit and preclinical positron emission tomography (PET) imaging, was carried out. RESULTS: High decay-corrected yields of [(18)F]FLT (16-39%) were reproducibly obtained. The product exhibited very high specific activity (4586.9TBq/mmol; 123,969Ci/mmol) and radiochemical purity (>99%). Overall, the [(18)F]FLT produced in this manner was superior to typical productions that utilized a GE TRACERlab FXF-N reaction module. Additionally, purification with SPE cartridges, followed by manual elution, accelerated overall run time and resulted in a two-fold increase in [(18)F]FLT concentration. PET imaging showed the [(18)F]FLT produced by this method was highly suitable for non-invasive tumor imaging in mice. CONCLUSIONS: The Bioscan Coincidence GE FDG Reaction Module was readily adapted to reproducibly provide [(18)F]FLT in high yield, specific activity, and radiochemical purity. The approach was suitable to provide sufficient amounts of material for preclinical studies.

A randomized, placebo-controlled trial of abacavir intensification in HIV-1-infected adults with virologic suppression on a protease inhibitor-containing regimen.

BACKGROUND AND OBJECTIVE: Maximizing the durability of viral suppression is a key goal of antiretroviral therapy. The objective of AIDS Clinical Trials Group Study 372A was to determine whether the intensification strategy of adding abacavir to an effective indinavir-dual nucleoside regimen would delay the time to virologic failure. METHODS: Zidovudine-experienced subjects (n=229) on therapy with indinavir + zidovudine + lamivudine with plasma HIV-1 RNA levels<500 copies/mL were randomized to abacavir 300 mg twice daily or placebo. The primary endpoint was the time to treatment failure, defined as a composite of confirmed virologic failure (2 consecutive HIV-1 RNAs>200 copies/mL) and treatment discontinuation. RESULTS: At baseline, the study population was 88% male with a median age of 41 years and median CD4 cell count of 250/mm3. Median follow-up was 4.4 years. The primary endpoint was reached in 61/116 of abacavir versus 62/113 of placebo recipients (P=.77); virologic failure occurred in 34/116 and 42/113 patients, respectively (P=.22). There were no differences in the proportions of subjects with plasma HIV-1 RNA levels below 50 copies/mL, in CD4 cell count increases, nor adverse events between the arms. In the study, 17% of subjects developed nephrolithiasis, 2% experienced abacavir hypersensitivity, and 4.8% experienced at least 1 serious cardiovascular event (7 [6%] in the abacavir arm, 4 [3.5%] in the placebo arm). In additional secondary and post hoc analyses, rates of intermittent viremia, suppression below a plasma HIV-1 RNA level of 6 copies/mL, and HIV-1 proviral DNA levels in peripheral blood mononuclear cells were not significantly different in the 2 arms. CONCLUSIONS: The strategy of intensification with abacavir in patients who are virologically suppressed on a stable antiretroviral regimen does not confer a clinical or virologic benefit. As antiretroviral regimens have become more potent since this trial was completed, it will be even more difficult to prove that late intensification of already virologically suppressed patients will add benefit. However, studies are warranted with drugs with new mechanisms of action to determine whether the level of persistent viremia below 50 copies/ mL can be further reduced and what influence this may have on latent HIV reservoirs.

Antiretroviral therapy for adult HIV-infected patients. Recommendations from a state-of-the-art conference. National Institute of Allergy and Infectious Diseases State-of-the-Art Panel on Anti-Retroviral Therapy for Adult HIV-Infected Patients.

This document summarizes recommendations from a state-of-the-art conference convened to evaluate the role of nucleoside analogue reverse transcriptase inhibitors in the treatment of human immunodeficiency virus (HIV) infection. Data from controlled clinical trials of zidovudine, didanosine, and zalcitabine were reviewed by an expert panel, which then formulated guidelines to assist clinicians and HIV-infected patients in the use of these agents. Recommendations were framed in the context of clinical scenarios for patients with asymptomatic HIV infection who have not had prior antiretroviral therapy; those with signs and symptoms of HIV-related disease who have not received prior therapy; clinically stable patients who are tolerating initial zidovudine therapy; patients experiencing clinical progression while on zidovudine therapy; and those who are intolerant of antiretroviral therapy. The panel concluded that physicians need to integrate up-to-date scientific knowledge with other relevant needs to improve the care of HIV-infected patients.