Kasia Kozlowski

Adherence Is the Critical Factor for Achieving Molecular Responses in Patients With Chronic Myeloid Leukemia Who Achieve Complete Cytogenetic Responses on Imatinib

PURPOSE There is a considerable variability in the level of molecular responses achieved with imatinib therapy in patients with chronic myeloid leukemia (CML). These differences could result from variable therapy adherence. METHODS Eighty-seven patients with chronic-phase CML treated with imatinib 400 mg/d for a median of 59.7 months (range, 25 to 104 months) who had achieved complete cytogenetic response had adherence monitored during a 3-month period by using a microelectronic monitoring device. Adherence was correlated with levels of molecular response. Other factors that could influence outcome were also analyzed. RESULTS Median adherence rate was 98% (range, 24% to 104%). Twenty-three patients (26.4%) had adherence <or= 90%; in 12 of these patients (14%), adherence was <or= 80%. There was a strong correlation between adherence rate (<or= 90% or > 90%) and the 6-year probability of a 3-log reduction (also known as major molecular response [MMR]) in BCR-ABL1 transcripts (28.4% v 94.5%; P < .001) and also complete molecular response (CMR; 0% v 43.8%; P = .002). Multivariate analysis identified adherence (relative risk [RR], 11.7; P = .001) and expression of the molecular human organic cation transporter-1 (RR, 1.79; P = .038) as the only independent predictors for MMR. Adherence was the only independent predictor for CMR. No molecular responses were observed when adherence was <or= 80% (P < .001). Patients whose imatinib doses were increased had poor adherence (86.4%). In this latter population, adherence was the only independent predictor for inability to achieve an MMR (RR, 17.66; P = .006). CONCLUSION In patients with CML treated with imatinib for some years, poor adherence may be the predominant reason for inability to obtain adequate molecular responses.

Poor adherence is the main reason for loss of CCyR and imatinib failure for chronic myeloid leukemia patients on long-term therapy.

We studied the relation between adherence to imatinib measured with microelectronic monitoring systems and the probabilities of losing a complete cytogenetic response (CCyR) and of imatinib failure in 87 CCyR chronic myeloid leukemia patients receiving long-term therapy. We included in our analysis the most relevant prognostic factors described to date. On multivariate analysis, the adherence rate and having failed to achieve a major molecular response were the only independent predictors for loss of CCyR and discontinuation of imatinib therapy. The 23 patients with an adherence rate less than or equal to 85% had a higher probability of losing their CCyR at 2 years (26.8% vs 1.5%, P = .0002) and a lower probability of remaining on imatinib (64.5% vs 90.6%, P = .006) than the 64 patients with an adherence rate more than 85%. In summary, we have shown that poor adherence is the principal factor contributing to the loss of cytogenetic responses and treatment failure in patients on long-term therapy.

18F-ICMT-11, a Caspase-3–Specific PET Tracer for Apoptosis: Biodistribution and Radiation Dosimetry

Effective anticancer therapy induces tumor cell death through apoptosis. Noninvasive monitoring of apoptosis during therapy may provide predictive outcome information and help tailor treatment. A caspase-3–specific imaging radiotracer, 18F-(S)-1-((1-(2-fluoroethyl)-1H-[1,2,3]-triazol-4-yl)methyl)-5-(2(2,4-difluorophenoxymethyl)-pyrrolidine-1-sulfonyl)isatin (18F-ICMT-11), has been developed for use in PET studies. We report the safety, biodistribution, and internal radiation dosimetry profiles of 18F-ICMT-11 in 8 healthy human volunteers. Methods: 18F-ICMT-11 was intravenously administered as a bolus injection (mean ± SD, 159 ± 2.75 MBq; range, 154–161 MBq) to 8 healthy volunteers (4 men, 4 women). Whole-body (vertex to mid thigh) PET/CT scans were acquired at 6 time points, up to 4 h after tracer injection. Serial whole blood, plasma, and urine samples were collected for radioactivity measurement and radiotracer stability. In vivo 18F activities were determined from quantitative analysis of the images, and time–activity curves were generated. The total numbers of disintegrations in each organ normalized to injected activity (residence times) were calculated as the area under the curve of the time–activity curve, normalized to injected activities and standard values of organ volumes. Dosimetry calculations were then performed using OLINDA/EXM 1.1. Results: Injection of 18F-ICMT-11 was well tolerated in all subjects, with no serious tracer-related adverse events reported. The mean effective dose averaged over both men and women was estimated to be 0.025 ± 0.004 mSv/MBq (men, 0.022 ± 0.004 mSv/MBq; women, 0.027 ± 0.004 mSv/MBq). The 5 organs receiving the highest absorbed dose (mGy/MBq), averaged over both men and women, were the gallbladder wall (0.59 ± 0.44), small intestine (0.12 ± 0.05), upper large intestinal wall (0.08 ± 0.07), urinary bladder wall (0.08 ± 0.02), and liver (0.07 ± 0.01). Elimination was both renal and via the hepatobiliary system. Conclusion: 18F-ICMT-11 is a safe PET tracer with a dosimetry profile comparable to other common 18F PET tracers. These data support the further development of 18F-ICMT-11 for clinical imaging of apoptosis.

Biodistribution and Radiation Dosimetry of Deuterium-Substituted 18F-Fluoromethyl-[1, 2-2H4]Choline in Healthy Volunteers

11C-choline and 18F-fluoromethylcholine (18F-FCH) have been used in patients to study tumor metabolic activity in vivo; however, both radiotracers are readily oxidized to respective betaine analogs, with metabolites detectable in plasma soon after injection of the radiotracer. A more metabolically stable FCH analog, 18F-fluoromethyl-[1,2-2H4]choline (18F-D4-FCH), based on the deuterium isotope effect, has been developed. We report the safety, biodistribution, and internal radiation dosimetry profiles of 18F-D4-FCH in 8 healthy human volunteers. Methods: 18F-D4-FCH was intravenously administered as a bolus injection (mean ± SD, 161 ± 2.17 MBq; range, 156–163 MBq) to 8 healthy volunteers (4 men, 4 women). Whole-body (vertex to mid thigh) PET/CT scans were acquired at 6 time points, up to 4 h after tracer injection. Serial whole-blood, plasma, and urine samples were collected for radioactivity measurement and plasma radiotracer metabolites. Tissue 18F radioactivities were determined from quantitative analysis of the images, and time–activity curves were generated. The total numbers of disintegrations in each organ normalized to injected activity (residence times) were calculated as the area under the curve of the time–activity curve normalized to injected activities and standard organ volumes. Dosimetry calculations were performed using OLINDA/EXM 1.1. Results: The injection of 18F-D4-FCH was well tolerated in all subjects, with no radiotracer-related serious adverse event reported. The mean effective dose averaged over both men and women (±SD) was estimated to be 0.025 ± 0.004 (men, 0.022 ± 0.002; women, 0.027 ± 0.002) mSv/MBq. The 5 organs receiving the highest absorbed dose (mGy/MBq) were the kidneys (0.106 ± 0.03), liver (0.094 ± 0.03), pancreas (0.066 ± 0.01), urinary bladder wall (0.047 ± 0.02), and adrenals (0.046 ± 0.01). Elimination was through the renal and hepatic systems. Conclusion: 18F-D4-FCH is a safe PET radiotracer with a dosimetry profile comparable to other common 18F PET tracers. These data support the further development of 18F-D4-FCH for clinical imaging of choline metabolism.

Clinical Translation of a ‘Click’ Labeled 18F-Octreotate Radioligand for Imaging Neuroendocrine Tumors

We conducted the first-in-human study of 18F-fluoroethyl triazole [Tyr3] octreotate (18F-FET-βAG-TOCA) in patients with neuroendocrine tumors (NETs) to evaluate biodistribution, dosimetry, and safety. Despite advances in clinical imaging, detection and quantification of NET activity remains a challenge, with no universally accepted imaging standard. Methods: Nine patients were enrolled. Eight patients had sporadic NETs, and 1 had multiple endocrine neoplasia type 1 syndrome. Patients received 137–163 MBq (mean ± SD, 155.7 ± 8 MBq) of 18F-FET-βAG-TOCA. Safety data were obtained during and 24 h after radioligand administration. Patients underwent detailed whole-body PET/CT multibed scanning over 4 h with sampling of venous bloods for radioactivity and radioactive metabolite quantification. Regions of interest were defined to derive individual and mean organ residence times; effective dose was calculated with OLINDA 1.1. Results: All patients tolerated 18F-FET-βAG-TOCA with no adverse events. Over 60% parent radioligand was present in plasma at 60 min. High tumor (primary and metastases)-to-background contrast images were observed. Physiologic distribution was seen in the pituitary, salivary glands, thyroid, and spleen, with low background distribution in the liver, an organ in which metastases commonly occur. The organs receiving highest absorbed dose were the gallbladder, spleen, stomach, liver, kidneys, and bladder. The calculated effective dose over all subjects (mean ± SD) was 0.029 ± 0.004 mSv/MBq. Conclusion: The favorable safety, imaging, and dosimetric profile makes 18F-FET-βAG-TOCA a promising candidate radioligand for staging and management of NETs. Clinical studies in an expanded cohort are ongoing to clinically qualify this agent.

Exploiting altered patterns of choline kinase-alpha expression on human prostate tissue to prognosticate prostate cancer

Aims Malignant transformation results in overexpression of choline-kinase (CHK) and altered choline metabolism, which is potentially detectable by immunohistochemistry (IHC). We investigated the utility of CHK-alpha (CHKA) IHC as a complement to current diagnostic investigation of prostate cancer by analysing expression patterns in normal (no evidence of malignancy) and malignant human prostate tissue samples. Methods As an initial validation, paraffin-embedded prostatectomy specimen blocks with both normal and malignant prostate tissue were analysed for CHKA protein and mRNA expression by western blot and quantitative reverse transcriptase PCR (qRT-PCR), respectively. Subsequently, 100 paraffin-embedded malignant prostate tumour and 25 normal prostate cores were stained for both Ki67 (labelling-index: LI) and CHKA expression. Results The validity of CHKA-antibody was verified using CHKA-transfected cells and siRNA knockdown. Immunoblotting of tissues showed good resolution of CHKA protein in malignant prostate, verifying use of the antibody for IHC. There was minimal qRT-PCR detectable CHKA mRNA in normal tissue, and conversely high expression in malignant prostate tissues. IHC of normal prostate cores showed mild (intensity) CHKA expression in only 28% (7/25) of samples with no Ki67 expression. In contrast, CHKA was expressed in all malignant prostate cores along with characteristically low proliferation (median 2% Ki67-LI; range 1–17%). Stratification of survival according to CHK intensity showed a trend towards lower progression-free survival with CHK score of 3. Conclusions Increased expression of CHKA, detectable by IHC, is seen in malignant lesions. This relatively simple cost-effective technique (IHC) could complement current diagnostic procedures for prostate cancer and, therefore, warrants further investigation.

Clinical translation of [18F]ICMT-11 for measuring chemotherapy-induced caspase 3/7 activation in breast and lung cancer

BackgroundEffective anticancer therapy is thought to involve induction of tumour cell death through apoptosis and/or necrosis. [18F]ICMT-11, an isatin sulfonamide caspase-3/7-specific radiotracer, has been developed for PET imaging and shown to have favourable dosimetry, safety, and biodistribution. We report the translation of [18F]ICMT-11 PET to measure chemotherapy-induced caspase-3/7 activation in breast and lung cancer patients receiving first-line therapy.ResultsBreast tumour SUVmax of [18F]ICMT-11 was low at baseline and unchanged following therapy. Measurement of M30/M60 cytokeratin-18 cleavage products showed that therapy was predominantly not apoptosis in nature. While increases in caspase-3 staining on breast histology were seen, post-treatment caspase-3 positivity values were only approximately 1%; this low level of caspase-3 could have limited sensitive detection by [18F]ICMT-11-PET. Fourteen out of 15 breast cancer patients responded to first–line chemotherapy (complete or partial response); one patient had stable disease. Four patients showed increases in regions of high tumour [18F]ICMT-11 intensity on voxel-wise analysis of tumour data (classed as PADS); response was not exclusive to patients with this phenotype. In patients with lung cancer, multi-parametric [18F]ICMT-11 PET and MRI (diffusion-weighted- and dynamic contrast enhanced-MRI) showed that PET changes were concordant with cell death in the absence of significant perfusion changes.ConclusionThis study highlights the potential use of [18F]ICMT-11 PET as a promising candidate for non-invasive imaging of caspase3/7 activation, and the difficulties encountered in assessing early-treatment responses. We summarize that tumour response could occur in the absence of predominant chemotherapy-induced caspase-3/7 activation measured non-invasively across entire tumour lesions in patients with breast and lung cancer.

Histogram analysis of apparent diffusion coefficient from whole-body diffusion-weighted MRI to predict early response to chemotherapy in patients with metastatic colorectal cancer: preliminary results

AIM To evaluate apparent diffusion coefficient (ADC) histogram analysis parameters, acquired from whole-body diffusion-weighted magnetic resonance imaging (DW-MRI), as very early predictors of response to chemotherapy in patients with metastatic colorectal cancer (mCRC). MATERIALS AND METHODS This was a single-institution prospective study, approved by the West Midlands-South Birmingham research ethics committee. All patients gave fully informed consent prior to imaging. Sixteen patients with histologically confirmed mCRC were enrolled to the study and 11 were successfully scanned with whole-body DW-MRI before (baseline) and 10.8±2.7 days after commencing chemotherapy (follow-up). Therapy response was assessed by RECIST 1.1. Mean ADC and histogram parameters (skewness, kurtosis, 25th, 50th, and 75th percentiles) were compared between progressors and non-progressors at baseline and follow-up. Receiver operating characteristics (ROC) analysis was performed for the statistically significant parameters. Data from metastases were also compared to normative tissue data acquired from healthy volunteers. RESULTS Three patients had progressive disease (progressors) and eight had partial response/stable disease (non-progressors). Mean, 25th, 50th, and 75th percentiles were significantly lower for progressors at baseline (p=0.012, 0.012, 0.012 and 0.025 respectively) with areas under the ROC curves (AUC)=0.58, 0.50, 0.58 and 0.63, respectively. Skewness and kurtosis were significantly lower for non-progressors at follow-up (p=0.001 and 0.003 respectively) with AUC=0.67 and 0.79 respectively. CONCLUSION ADC histogram analysis shows potential in discriminating progressive from non-progressive disease in patients with mCRC, who underwent whole-body DW-MRI. The technique can potentially be tested as a response assessment methodology in larger trials.

EVALUATION OF CASPASE-3 ACTIVATION IN AN ALZHEIMER’S DISEASE POPULATION USING [ 18 F]ICMT-11 PET/CT

Neuropathological studies have shown that tau accumulation is closely linked to cognitive decline. Using [F]AV1451 PET it is now possible to quantify tau pathology in vivo. The aim of this study was to investigate specific [F]AV1451 binding in relation to amyloid status and neuropsychological performance in cognitively normal subjects with SCD. Methods: 23 subjects with SCD (age 6667, 52% female, MMSE: 2861) underwent both 90 minute dynamic [F]florbetapir (amyloid) and 130 minute dynamic [F]AV1451 (tau) PET scans, and an extensive neuropsychological test battery. [F]Florbetapir scans were read visually as positive or negative for presence of cerebral amyloid. Reference parametric mapping (RPM) with cerebellar grey matter as reference region was used to calculate [F]AV1451 binding potential (BPND). Results were analysed for 1) medial temporal lobe (MTL), known as the first region to harbour tau pathology in aging, 2) a global region (neocortex), and 3) putamen, a region thought to represent “off-target” binding. Raw neuropsychological test scores were converted into z-scores and combined into composite scores for episodic memory. Results: [F]Florbetapir positive subjects (n1⁄47) showed higher [F]AV1451 BPND than [F]florbetapir negative subjects (n1⁄416) in MTL (0.2160.18 vs -0.0460.05, p<0.01) and neocortex (0.1460.06 vs 0.0260.04, p<0.01). Adjusted for age, sex and education, lower episodic memory scores were, although at trend level, associated with higher [F]AV1451 BPND in MTL (b1⁄4-0.52, p1⁄40.06) and neocortex (b1⁄4-0.49, p1⁄40.07), but not putamen (b1⁄4-0.25, p1⁄40.43). Across all subjects, regardless of amyloid status, higher age correlated with higher [F]AV1451 BPND in the putamen (Pearson’s r 1⁄4 0.66, p<0.01), but not with [F]AV1451 BPNDin MTL and neocortex. Conclusions:These preliminary data suggest that tau load in AD specific regions of patients with SCD is higher in amyloid positive than in amyloid negative subjects. In addition, tau accumulation in MTL and neocortex might be associated with poorer episodic memory performance. This highlights the potential of tau PET to capture early and subtle cognitive changes in subjects with SCD.

Abstract P5-01-02: Evaluation of apoptosis in breast cancer using the novel PET probe [18F]ICMT-11 in patients treated with neoadjuvant FEC chemotherapy: Initial assessment of optimum imaging time and relation to caspase-3 immunostaining

Background: [18F]ICMT-11 is an isatin analogue which has been developed by our group as a novel PET radiotracer for studies of apoptosis in vivo. Preclinical studies have demonstrated subnanomolar affinity to caspase 3, and validated the potential for imaging apoptosis in xenograft models. A first-in-man study showed that the agent was well tolerated with acceptable dosimetry. This is the first study of this agent to measure the effect of chemotherapy on radiotracer uptake in patients. As apoptosis is a dynamic process, one of the main objectives of the study was to determine the optimal time-point for imaging post-chemotherapy and compare the results with immunohistochemistry assessments at the same time-points. The study was approved by a regional ethics committee and ARSAC. Methods: 7 patients with breast tumour lesions measuring 15mm or more, due to undergo neoadjuvant chemotherapy with FEC (5FU, Epirubicin, Cyclophosphamide) had dynamic PET scans for 66mins 30seconds following intravenous injection of [18F]ICMT-11 with a mean activity of 340.82 Mbq±20.76 and Specific Activity range of 447.014-5128.34 Gbq/µmol prior to chemotherapy and 24h-2 weeks post-chemotherapy. A breast biopsy was also obtained within a few hours of the 2nd PET scan to correlate apoptosis in the breast tissue utilising TUNEL and Caspase 3 staining by immunohistochemistry. Volumes of interest were drawn manually and analyzed using Analyze software®. Results: The scans were well tolerated in all patients. Uptake of [18F]ICMT-11 was demonstrated in all tumor lesions. The tumours studied included ER positive and PR positive, HER2 positive and triple negative patients. The first cohort patients were imaged pre-chemotherapy and 24-48h post chemotherapy. Tumour to Breast ratio (TBR) showed an increase from 1.42±0.21(pre) to 1.71±0.33 (post). Tumour to muscle ratio (TMR) was not increased, 1.52±0.30(pre) and 1.22±0.09 (post). In addition, an increase the SUV was noted in the lymph nodes of patients, at both 24 and 48h. (SUVav 0.39±0.02 (pre), 0.45±0.03 (post), and SUVmax 0.87± 0.02(pre) ,1.22±0.12 (post). The lymph nodes were however not sampled for immunohistochemistry. A further cohort of patients had the follow-up scan 2 weeks post chemotherapy, TBR and TMR were both increased in this cohort 1.50±0.22 (pre), 2.52±0.48 (post),and 1.82±0.10 (pre), 2.08±0.0.04 (post), respectively. Caspase and TUNEL labelling with immunohistochemistry also showed increased in apoptosis in the breast biopsies at 2 weeks compared to baseline in keeping with the PET data. Conclusion: These preliminary data suggest that [18F]ICMT-11 is a promising marker for chemotherapy induced apoptosis in vivo, and correlates with findings in tumor biospsies using TUNEL and immunostaining for caspase 3. Further work is underway to study a larger cohort of patients, and identify the optimal PET pharmacokinetic parameter to describe [18F]ICMT-11 uptake and retention. Citation Format: Shairoz Merchant, Eric O Aboagye, Adrian Lim, Kasia Kozlowski, Naina Patel, Jennifer Steel, Susan Cleator, Sami Shousha, Vidhya Varghese, Raoul C Coombes, Laura Kenny. Evaluation of apoptosis in breast cancer using the novel PET probe [18F]ICMT-11 in patients treated with neoadjuvant FEC chemotherapy: Initial assessment of optimum imaging time and relation to caspase-3 immunostaining [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-01-02.