EARLY RELEASE: The Journal of Clinical Endocrinology & Metabolism
The Endocrine Society
[ 123I]Iodometomidate Imaging in Adrenocortical Carcinoma
Michael C. Kreissl*1, Andreas Schirbel*1, Martin Fassnacht2, Heribert Haenscheid1, Frederik A. Verburg1,3, Stefanie Bock2, Wolfgang Saeger4, Pascal Knoedler5, Christoph Reiners1, Andreas K. Buck1, Bruno Allolio*2, Stefanie Hahner*2
1Department of Nuclear Medicine, University Hospital of Wuerzburg, University of Wuerzburg, Oberduerrbacher Strasse 6, D-97080 Wuerzburg, Germany; 2Endocrinology & Diabetes Unit, Department of Internal Medicine I, University Hospital of Wuerzburg, University of Wuerzburg, Oberduerrbacher Strasse 6, D-97080 Wuerzburg, Germany; 3Department of Nuclear Medicine, University Hospital of Aachen, Aachen University, Pauwelsstrasse 30, D-52074 Aachen, Germany;
4Department of Pathology, Marienkrankenhaus, Alfredstrasse 9, D-22087 Hamburg, Germany;
5Department of Radiology, University Hospital of Wuerzburg, University of Wuerzburg, Oberduerrbacher Strasse 6, D-97080 Wuerzburg, Germany
Context: Imaging with [123I]iodometomidate ([123I]IMTO) has been shown to diagnose adreno- cortical lesions with high sensitivity and specificity.
Objective: Clinical utility of [123I]IMTO imaging in adrenocortical carcinoma (ACC).
Design: Prospective monocentric diagnostic study and prospective case series. Single tertiary re- ferral center.
Patients and Interventions: 58 patients with histologically confirmed ACC all ENSAT IV received 185 MBq of [123I]IMTO. Sequential planar whole body scans until 24 hours p.i. and SPECT/CT hybrid imaging 4 - 6 h p.i. were performed.
Main Outcome Measures: Uptake of [123I]IMTO in ACC lesions. Sensitivity and specificity of [123I]IMTO imaging compared to conventional imaging. Number of patients eligible for [13] ]]IMTO therapy.
Results: Of 430 lesions detected by conventional imaging, 30% showed strong, 8% moderate and 62% no tracer accumulation. [123I]IMTO detects both primaries and metastatic lesions of ACC. However, a substantial percentage of lesions fails to show [123I]IMTO uptake. The overall sensitivity and specificity values were 38% and 100%, respectively. 34 (59%) patients had at least one [ 123I]IMTO-positive lesion. Cortisol and aldosterone secretion by ACC was positively correlated to [123|]IMTO uptake (P=0.01) .; cytotoxic chemotherapy and mitotane treatment did presumably not influence tracer uptake. 21 patients (36.2%) had radiotracer uptake in all lesions ≥ 2 cm and therefore were potential candidates for targeted systemic radiotherapy with [13]]]IMTO.
Conclusion: About one third of patients with ACC show specific retention of [123I]IMTO in meta- static lesions. This study provides support for the conduct of a prospective trial to determine if the first molecular informed therapy using [131I]IMTO will be of value to patients with metastatic ACC.
E tomidate and some of its analogs like metomidate, fluoroetomidate and iodometomidate bind with high avidity and affinity to the adrenocortical CYP11B en-
zymes 11ß-hydroxylase (CYP11B1) and aldosterone syn- thase (CYP11B2) (1-3). Accordingly, [11C]metomidate and [123I]iodometomidate ([123I]IMTO) tracers have been shown to allow imaging of benign adrenocortical lesions
with high sensitivity and specificity (1, 4-7), thereby non- invasively providing important diagnostic information and providing an alternative to the use of radiocholesterol imaging ([131I]-6ß-iodomethyl-norcholesterol (NP-59), [75Se]-60-selenomethyl-19-norcholesterol (Scintadren)) (8-15).
Studies using [11C]metomidate in adrenocortical can- cer (ACC) also demonstrated significant uptake in most cases suggesting that imaging of CYP11B enzymes may be useful also in ACC (16). However, the number of ACC patients studied with [11 C]metomidate positron emission tomography (PET) was small (n = 13) and some ACCs failed to show uptake of [11 C]metomidate. We, therefore, here present data of [123I]IMTO imaging in a large cohort of patients with ACC to comprehensively assess the clin- ical utility of IMTO imaging in ACC.
We hypothesized that [123IJIMTO imaging might be helpful to demonstrate the adrenocortical origin in non- secreting ACC and may hold the potential to detect me- tastases or local recurrences not visualized by computer- ized tomography (CT). Furthermore, as it has been shown that targeted radionuclide therapy with [131IJIMTO may be effective in some patients with stage IV ACC (17), we were interested to know what percentage of ACC patients would potentially qualify for such a treatment and whether pretreatment with mitotane and/or cytotoxic che- motherapy might negatively impact on the uptake of [123IJIMTO in ACC.
Subjects and Methods
Patients
This is the first study reporting on the biodistribution of [123IJIMTO in ACC. 20 patients with ACC were investigated within a diagnostic pilot trial assessing the clinical utility of [123IJIMTO for differentiation of adrenocortical from non ad- renocortical lesions (18). We observed high tracer uptake in a subcohort of ACC patients and, consecutively, patients with fa- vorable biodistribution were offered treatment using [13]]]IMTO. First results of IMTO related therapy have been recently published (17). Due to the limited treatment options in patients with metastatic ACC, [123IJIMTO imaging was offered to 41 additional patients with ACC, based on compassionate use. The combination of the two cohorts of patients with ACC was chosen to here present data from a larger patient sample. Patients with a history of histologically confirmed ACC and lesions de- tected by computed tomography (CT) or magnet resonance im- aging (MRI) were included. Further inclusion criteria were a negative pregnancy test and established contraception in females of childbearing age as well as the ability and willingness to give written informed consent. Exclusion criteria were pregnancy or breast feeding and renal failure (serum creatinine > 2 mg/dl).
Copyright @ 20132013 by The Endocrine Society
Received September 2, 2012. Accepted April 15, 2013.
All patients had undergone CT using i.v. contrast enhance- ment and/or MRI using standard imaging protocols within 6 wk before or after gamma camera imaging with [123IJIMTO. The secretory status of the tumors at the time of primary diagnosis was determined by an experienced endocrinologist upon review of the results of a detailed hormonal workup following the guide- lines of the European Network for the Study of Adrenal Tumors (ENS@T; www.ensat.org/acc). As both aldosterone synthase and 11-B-hydroxylase represent the targets of [123IJIMTO, the tumors were classified either as aldosterone and/or cortisol (a/c) secreting or not a/c secreting. The proliferation index (Ki67) was determined from the tumor samples and used to establish the diagnosis of ACC; in 55 patients the proliferation index was available.
Radiopharmaceutical
[123IJIMTO was prepared as previously described (19). Briefly, about 260 MBq [123I]iodide in 0.05 N NaOH (CYI.9; GE Healthcare, Braunschweig, Germany) were added to a solu- tion of 30 µg of the stannylated precursor in 25 uL ethanol. To initiate the reaction, 6 pL 1 N HCI and 10 uL chloramine-T (1.5 mg/mL) were added. The reaction was allowed to proceed at room temperature for 3 min and quenched by the addition of 6 AL 1 N NaOH. Finally 10 µL Na2S2O5 (4 mg/mL) were added in order to reduce oxidized radioiodine species to iodide. The solution was injected into a HPLC system equipped with an analytical RP-18 column (Kromasil 100-5℃18, 250 × 4.6 mm; CS Chromatographie Service, Langerwehe, Germany). HPLC separation was performed using ethanol/water/ammonia 50/ 50/1 as eluent with a flow of 1.0 ml/min. The [123I]IMTO con- taining fraction was collected and evaporated to dryness at room temperature under reduced pressure. Heating during this step should be strictly avoided in order to suppress deiodination and to maintain high radiochemical purity. For i.v .- injection, the res- idue was redissolved in a suitable volume of PBS/ethanol 80/20 and passed through a sterile 0.22 um Millipore filter into a sterile vial.
[123I]IMTO image evaluation
Acute and chronic toxicities after injection were assessed ac- cording to the Common Toxicity Criteria (CTCAE) of the Na- tional Cancer Institute (version 4.0). For all planar images, a dual-head gamma camera (Siemens ECAM Duet, Germany) equipped with a medium-energy parallel-hole collimator was used. Thirty minutes before injection of the radiotracer, free ra- dioiodine uptake into the thyroid gland was blocked by admin- istration of sodium perchlorate (1,150 mg) orally. Thyroid blockage was continued for 3 d with 460 mg sodium perchlorate 3 times daily. 185 MBq [123IJIMTO were intravenously (IV) injected. Planar scans of the whole body were performed with a dual head gamma camera (Siemens Ecam Duet, Germany) 5 min, 45 min, 90 min, 4 h, 6 h and 21-24 h post injection using a standard technique (window setting 159 keV ± 7.5%, bed speed 20 cm/min, matrix 256 × 1024, no auto contour) in the initial 20 patients. In the remaining patients, imaging included at least 1 planar scan (with the scanning parameters as mentioned above) 4-6 h post injection. All patients except for one also received SPECT/CT imaging between 4 and 6 h post injection, which was
Abbreviations:
performed on a dedicated SPECT/CT camera system (Siemens Symbia T2, Germany). SPECT parameters were window setting 159 keV ± 7.5%, rotation 180° per detector head with 3º an- gular step (= 2 × 60 frames) at 30 s per projection, autocontour, step and shoot, 128 × 128 matrix, slice thickness 4.8 mm. The low-dose CT was acquired using 130 kV and 17 mAs (recon- structed slice thickness 5 mm). SPECT data were corrected for attenuation and reconstructed iteratively using an ordered subset expectation maximization (OSEM) algorithm (6 subsets, 6 iter- ations, 3D smoothing 8 mm). For attenuation correction, CT data were reconstructed using a B08s kernel, for visual interpre- tation and image fusion data were also reconstructed using a B30S kernel. Due to a camera breakdown one SPECT/CT scan could not been performed and SPECT-only data were used. For image fusion and display the data were also reconstructed using a B30S kernel.
The spatial resolution was 13 mm full width at half maximum in the planar scans and 11 mm in reconstructed SPECT/CT data both measured with a 123I line source centered in a water filled phantom with 26 cm diameter to mimic scatter and attenuation in a patient.
CT/MRI image analysis
Besides the low-dose-CT acquired in the context of SPECT/ CT, 47 patients had a recent contrast-enhanced spiral CT of the chest and abdomen. Morphological imaging of the chest was available in 8 patients and of the abdomen in 3 patients. Diag- nostic CT and, in 3 patients, also MRI data were analyzed along with the low-dose-CT from the SPECT/CT by a board certified radiologist who was unaware of the patients’ history or findings from other studies. The 5 largest lesions in each organ/location were registered, along with their maximal diameters. The radi- ologist also classified the lesions in terms of being suspicious for local relapse, local lymph node metastases and distant lymph node metastases (again max. 5 lesions per location). Conven- tional imaging served as reference for the calculation of sensi- tivity and specificity values of [123IJIMTO imaging.
Image analysis and evaluation
Semiquantitative analysis
The objective of the quantitative analysis of tumor lesions in planar scans was to identify the time point of optimum contrast. For the assessment of the planar scans in the initial 19 patients which were imaged in the context of the clinical trial with com- plete sets of data, ventral and dorsal views of the whole body scans of all time points were aligned and superimposed onto each other. The most suitable view (dorsal/frontal) for the visualiza- tion was determined for each lesion. Then a circular ROI (Ø 2 cm) was assigned to the region of highest tracer uptake within each lesion. A second circular ROI of the same size was placed next to the lesion ROI within the same organ and served as background ROI for the determination of the tumor to back- ground ratio. Only lesions, which could be clearly delineated, were assessed. Ratios were only calculated for those time points on which the lesions were visualized on the whole body scan. Up to 5 tumor lesions (primary tumor, local recurrence and metas- tases) were analyzed. Mean pixel counts were used for the cal- culation of ratios.
Semiquantitative analysis of the attenuation corrected SPECT data was performed using up to 5 spherical volumes of interest
(VOIs; Ø 2 cm) which were assigned up to 5 of the most prom- inent tumor lesions visualized by SPECT/CT. One further VOI was placed to the liver adjacent to the right adrenal gland (box 2 × 3 x 3 cm). Mean voxel counts were calculated for the de- termination of tumor-to-liver ratios.
Given the inherent spatial resolution of 11-13 mm of the scintigraphic images, it must be expected that tumor to back- ground or tumor to liver ratios are increasingly underestimated by the analysis with decreasing diameters of less than 2-3 cm due to the partial volume effect by spill-over and, if the lesion is smaller than the VOI, by the tissue-fraction effect i.e., averaging tumor and benign tissue included in the VOI.
Visual analysis
For visual image analysis and interpretation, [123I]IMTO da- tasets i.e., planar imaging together with SPECT/CT data were reviewed by two experienced nuclear medicine physicians (A.K.B. and M.C.K.) together with an endocrinologist (S.H. or M.F.) in consensus. The readers were not aware of the patient identity. Uptake in each tumor lesion described on CT was graded as “0”: No uptake, “1”: Moderate uptake, “2”: Strong uptake. For the analysis of sensitivity and specificity, lesions with uptake grade 1 and 2 were coded as positive.
Metastatic lesions visualized by [123IJIMTO in addition to those detected by conventional imaging were registered. A pa- tient was considered to be [123I]IMTO-positive if at least one lesion detected by CT displayed unequivocal uptake of [123IJIMTO. It was also assessed if patients were potentially el- igible for systemic targeted radionuclide therapy using [131IJIMTO. In order to achieve a good therapeutic effect of [13]]]IMTO, all lesions > 2cm were expected to show moderate or high tracer uptake; patients meeting this criterion were con- sidered eligible for radionuclide-based therapy with [13]]]IMTO.
We also determined the utility of SPECT and SPECT/CT re- garding lesion detection. For this purpose, the number of lesions found by planar scintigraphy in the body area covered by SPECT imaging was compared to the number of lesions visualized by SPECT. Furthermore, the number of additional lesions detected by SPECT/CT, including low-dose-CT compared to SPECT only was assessed. The number of additional lesions was limited to five per organ
Statistical analysis
Results are expressed as mean ± SD or median (range). All data was analyzed using IBM SPSS Statistics 20 (IBM Corp., Armonk, NY, USA). The relationship between IMTO positivity and survival was tested using Kaplan-Meier survival analysis, employing a log-rank test in order to test for differences between survival curves of different groups. To assess the relationship between IMTO positivity and prior treatments, current mitotane therapy and serum mitotane levels a logistic regression analysis was performed. For comparing suitability for [131IJIMTO ther- apy among the patients with and prior mitotane/cytotoxic che- motherapy a Chi-Square-Test was applied. The relationship be- tween the proliferation index Ki67 and intensity of IMTO uptake as well as survival and suitability for [131IJIMTO therapy was assessed using a Spearman correlation. P values < 0.05 were considered statistically significant.
Ethical considerations
The study comprises both prospective and retrospective eval- uations. Nineteen ACC patients imaged in the context of a phase I/II study gave their informed consent prior to all study related procedures and were also subjected to a standardized imaging protocol as mentioned above. The study was approved by the German Federal Institute for Drugs and Medical Devices (BfArM) (Permit No. 4031230), the local ethics committee of the University of Wuerzburg (Permit No. 100/05) and the German Federal Office for Radiation Protection (BfS) (Permit No. Z5-22461/2-2006-024).
As mentioned above, further [123IJIMTO investigations were performed on a compassionate use basis after obtaining written informed consent from each patient.
Results
Patients
Sixty-one patients with histologically proven ACC and known tumor lesions (primary tumor, local relapse, me-
tastases) were studied with [123IJIMTO between May 2006 and October 2010. Patient characteristics are given in Table 1. 12 patients with the ACC still in situ were also included in an analysis of the utility of [123IJIMTO in a total 51 patients with adrenal lesions which will be pub- lished elsewhere.
Cortisol or aldosterone hypersecretion was observed in 22 patients. In 57/58 patients, tumor material was as- sessed by the reference pathologist of the German ACC Registry to confirm the diagnosis of ACC (W.S.). In the remaining patient, the diagnosis of ACC was considered certain because of a diagnosis of ACC by the local pathol- ogist together with laboratory and clinical evidence of glu- cocorticoid excess. 42 patients had received prior treat- ment with mitotane. Of these, 17 were still on treatment with mitotane. Blood mitotane levels had been measured within 6 wk of the [123I]IMTO study in all patients taking mitotane and in 17/25 patients who had stopped mitotane.
| Sex (m/f) | 21m/37f |
|---|---|
| Weight (kg) | 72.8 ± 15.1 |
| BMI (kg/m2) | 24.9 ± 3.8 |
| Age (years) Cortisol and/or aldosterone secretion at time of diagnosis | 52.1 ± 15.8 |
| - secretion | 22 |
| - no secretion | 39 |
| Treatment naïve ACC | 3 |
| Prior resection of primary tumor | 46 |
| Local recurrence / residual tumor | 16 |
| Metastatic disease | 58 |
| Mitotane therapy: - current | 17 |
| - previous | 25 |
| Mean mitotane level of patients currently on mitotane (mg/liter) | 13.7 ± 10.1 |
| Chemotherapy - within 6 weeks of imaging | 10 |
| - > 6 weeks prior to imaging | 20 |
| No prior systemic therapy (mitotane or chemotherapy) | 12 |
| Survival in months (median; range) | 18 (0.4-63) |
| Chemotherapy regimens used before imaging (median; range) | 1 (0 - 5) |
| Chemotherapy regimens used before imaging (median; range) | 1 (0 - 6) |
| Most commonly used chemotherapy regimens (no patients) before and after IMTO imaging | Streptozocin (36) |
| EDP (33) | |
| Sunitinib (15) | |
| Trofosfamide (8) | |
| Gemcitabine-Erlotinib (7) Bevacizumab-Capecitabine (7) |
In 47 patients the primary tumor had initially been re- sected and 29 patients had received cytotoxic chemother- apy for advanced disease, 10 of them had had chemother- apy within 6 wk prior to imaging. All patients were registered with the German ACC Registry (20) and were followed for a median of 42 mo (range 21 - 63).
Visual assessment of [123I]IMTO uptake
Representative imaging results using [123IJIMTO in ACC can be found in Figure 1. On morphological assess- ment of CT / MRI images, 430 lesions were documented. 266 (62%) did not show any tracer uptake, 34 (8%) had a moderate and 130 (30%) a strong uptake of the radio- tracer. We did not observe any false positive lesions, there-
fore the specificity of [123IJIMTO imaging is 100%. The highest number of [123IJIMTO positive lesions and there- fore also the highest sensitivity was observed in local re- currences and soft tissue metastases. The lowest number was found in lung, peritoneum and pleura, where the me- dian diameter also was the smallest (Figure 2a). In order to assess the relevance of lesion size on [123I]IMTO positiv- ity/sensitivity, tracer uptake is plotted in relation to the maximal diameter of the metastatic lesion in Figure 2b. Only 5.0% of the metastases smaller than 10 mm were [123IJIMTO positive, whereas 40%-50% of metastases ≥ 30 mm were positive
In addition to the lesions seen on conventional imaging,
PID:2002544806
b
PID:2002583924
PID:2002601178
a
c
LDR
>
>
LDR
LDR
d
e
f
g
R VL
R VL
R VL
LDR
LDR
PID:2002509439
PID:2002564717
PID:2002476584
PID:2002506827
a
100%
Sensitivity / Percent of metastases
90%
negative
80%
moderately positive
70%
strongly positive
60%
50%
40%
30%
20%
10%
0%
Max .~ (mm): No. of lesions (n):
< 10
10-19
20-29
30-39
40-49
≥50
76
114
84
43
40
41
b
100%
Sensitivity / Percent of lesions
90%
O negative
80%
O weakly positive
70%
Istrongly positive
60%
50%
40%
30%
20%
10%
0%
| Localization: | local relapse | liver | lymph node | lung | peri- toneum | pleura | soft tissue | bone |
|---|---|---|---|---|---|---|---|---|
| No. of lesions (n): | 20 | 95 | 62 | 156 | 22 | 11 | 13 | 11 |
| Median diameter (mm): | 57 | 39 | 23 | 13 | 12 | 12 | 23 | 37 |
c
100%
90%
*
Percentage of IMTO positive patients
80%
70%
60%
50%
40%
30%
20%
10%
0%
c/a secreting
c/a non-secreting
History of mitotane
No history of mitotane
Currently on mitotane
Currently not on mitotane
Prior chemotherapy
No prior chemotherapy
12 additional foci of abnormal tracer uptake were de- tected in 6 patients. Three of those were found outside the field of view of CT imaging, 9 inside the field of view. 11 lesions could be confirmed by follow-up or reevaluation using conventional imaging.
On a patient-based evaluation, 34 of 58 (59%) patients
were found to be [123I]IMTO-posi- tive, 24 (41%) did not show any foci of abnormal uptake of the radiotracer.
A significant correlation was noted between IMTO positivity and initial a/c secretion by the tumor (P = .01). 80.0% of the patients with a aldosterone/cortisol secreting ACC at initial evaluation had at least one [123I]IMTO-positive lesion and therefore were positive on IMTO im- aging (Figure 2c). In patients not ex- hibiting increased aldosterone/corti- sol production, 47.4% showed [123I]IMTO uptake in at least one tu- mor lesion (Figure 2c).
Of the patients with moderate or strong uptake of the radiotracer, 41% had received chemotherapy, 24% were on current mitotane med- ication. In contrast, 58% of the [123I]IMTO-negative patients had been treated with chemotherapy be- fore and 33% had received mitotane or were on current mitotane therapy. On logistic regression analysis, no significant influence of prior thera- pies and current mitotane therapy on [123I]IMTO uptake could be found. Furthermore, there was no signifi- cant correlation of [123I]IMTO up- take to serum mitotane levels. There was no significant difference in sur- vival between those patients who showed [123I]IMTO positivity in at least one lesion and those in whom no lesions were positive (P = . 48). Of the 3 patients with treatment naïve primary ACC, 2 were [123I]IMTO negative and 1 was positive (Figure 1a, 1b).
21 patients (36.2%) had radio- tracer uptake in all lesions sized 2 cm or larger and therefore met the major prerequisite for targeted systemic ra- diotherapy with [131IJIMTO. 4/5 (80.0%) of the patients without previous systemic therapy were suitable for [131I]IMTO treatment, whereas in the group of patients who had received systemic treatment either with chemotherapy and/or mitotane only 16/29 (55.2%) qualified for radiotherapy based on [123IJIMTO
uptake in their tumor lesions. However, this difference did not prove to be significant (P = . 41). There was no sig- nificant difference in survival between those patients who showed [123IJIMTO positivity in at least one lesion and those in whom no lesions were positive (P = . 46) and between those patients suitable for treatment with [131IJIMTO and those not suitable (P = . 71).
On correlation analysis between the Ki67 index and IMTO uptake, on a per patient basis or eligibility for IMTO treatment, IMTO positivity showed a tendency to- wards a negative correlation with Ki67, indicating higher probability of IMTO uptake in more differentiated tissue (r= - 0.283, P = . 054). Eligibility for treatment was not significantly correlated with Ki67 (r = - 0.141, P = . 34), whereas overall survival was significantly negatively cor- related with Ki67 (r= - 0.331, P = . 023).
When assessing the influence of the imaging modalities, planar scintigraphy versus SPECT alone versus SPECT/ CT, we found more lesions with SPECT as compared to planar imaging in 40% of patients. On a lesion basis, SPECT detected 67% more lesions (165 vs. 99). SPECT/CT also found more lesions as compared to SPECT alone in 68% of patients, mainly due to the de- tection of small lung lesions with the low-dose-CT as part of SPECT/CT. On a lesion basis, 85% more lesions were seen (306 vs. 165) as compared to nonhybrid functional imaging.
Semiquantitative assessment of [123I]IMTO uptake
On planar gamma camera imaging, 41 foci of patho- logical tracer uptake were detected in 15 of the 19 patients with complete sets of data. As shown in Figure 3, the high- est tumor to background ratio was observed in most le- sions at the latest time point (22-24 h p.i.). However, 5 lesions showed the highest uptake ratio already 5 min after injection. The analysis of the time point of optimal con- trast is independent on any systematical underestimate of the ratios of an analyzed lesion due to partial volume ef-
20
Number of lesions
15
10
5
0
5 min
45 min
90 min
4 h
6 h
22-24 h
Imaging time point
fect. According to the analysis as described above with a potential underestimate of the values deduced for small lesions, the median tumor to background ratio was 2.1 (range 1.2 - 10.8) A representative example is shown in Figure 4.
In keeping with planar imaging, on semiquantitative evaluation of the SPECT/CT studies, a variable uptake of the radiotracer was noted. Some lesions were only visu- alized in the CT part of the SPECT/CT and therefore had a low tumor-to-liver ratio whereas other lesions displayed a strong accumulation of the radiotracer. The median tu- mor to liver ratio was 2.1 (range 0.2 - 18.8, n = 51 lesions).
Side effects related to the administration of IMTO, as assessed by CTC criteria
In terms of acute reactions, a single patient developed symptoms of flush with short-term dyspnea and tachycar- dia, which did not require intervention and subsided within 5 min (CTCAE grade 1). Another patient suffered from back pain during imaging (CTCAE grade 1) which was attributed to his overweight. For the analysis of cre- atinine levels after one year, data were available from 23/34 surviving patients. All except for one patient who had 4 chemotherapy regimens (streptozotocin, etoposide&doxorubicin&cisplatin, bevacicumab&capecitabine and thalidomide), showed stable values. On long-term follow-up (>2 y), no side ef- fects attributable to the injection of the radiotracer were observed.
Discussion
For the first time we have evaluated the utility of [123IJIMTO imaging in a large sample of patients with ACC demonstrating that most patients exhibit tracer up- take in some or all ACC lesions.
While, as expected, the percentage of patients with [123IJIMTO uptake in primary or metastatic lesions was significantly higher in a/c secreting ACC, still a large per- centage of ACC not secreting aldosterone or cortisol showed uptake of [123IJIMTO thereby noninvasively es- tablishing the adrenocortical origin of the respective pos- itive lesions. Thus, [123IJIMTO could become a particu- larly useful tool to establish a diagnosis of ACC in nonsecretory adrenocortical malignancies, potentially even affecting the surgical strategy. In addition, also tak- ing into account the observed specificity of 100% high uptake of [123IJIMTO by a single metastatic lesion estab- lishes stage IV ACC without the need of further histo- pathological confirmation, again potentially affecting
LDR
5 min
45 min
90 min
4 h
6 h
23 h
treatment strategies. However, further confirmatory phase II/III studies with histopathological correlation are necessary.
However, a large percentage of metastatic lesions de- tected by CT failed to show [123IJIMTO uptake, especially the sensitivity for detecting lung metastases is limited. Sev- eral reasons probably account for this observation. The percentage of [123IJIMTO positive lesions increased with increasing diameter of metastases reaching a plateau at a diameter of ≥ 3 cm. This indicates that SPECT with its limited spatial resolution (11 mm full width at half max- imum) may fail to detect some lesions expressing CYP11B enzymes with a diameter < 2cm. For smaller lesions, the pattern of scintigraphic counts is more and more deter- mined by the point spread function of the detection system defining a minimal volume of distribution. As the lesion mass decreases rapidly with decreasing diameter, the CYP11B expressing mass becomes too small to induce a significant signal within this volume. Use of [124]]IMTO PET in ACC with its higher resolution may theoretically increase the resolution and sensitivity, furthermore the longer half-life of 124I may overcome the disadvantages of 11C. However, currently no data on [124IJIMTO PET in ACC have been published. Also, a correlation with [18F]- FDG PET, which has been shown to be a sensitive imaging tool for ACC and adrenal lesions should be performed in the future (6, 7, 21-27). From our large series it is clear that also other mechanisms account for the substantial per- centage of negative lesions with a diameter > 3 cm. Lack of [11C]metomidate uptake in ACC has also been reported by Hennings et al. (5) and has been related to extensive tumor necrosis as demonstrated by histopathology. Thus, in some larger lesions the amount of remaining viable pro- liferating cells may become too small for detection by
[123IJIMTO imaging. In addition, low or completely miss- ing expression of CYP11B enzymes may account for neg- ative lesions. In some patients positive and [123IJIMTO negative lesions coexist, which might be attributable to tumor evolution and associated loss of expression of CYP11B enzymes in some tumor cell clones. Tumor het- erogeneity is increasingly becoming the focus of research. Using exome sequencing, chromosome aberration analy- sis and ploidy profiling, Gerlinger et al. have recently dem- onstrated this heterogeneity on multiple spatially sepa- rated samples obtained from primary renal carcinomas (28). Low or absent CYP11B may be present already in the primary tumor and may be the cause of uniformly negative lesions in some ACC patients. When correlating the pro- liferation index Ki67 with IMTO positivity, we observed a trend towards a lower uptake in higher proliferative tumors, however the tumor samples assessed where from the primary tumors whereas the IMTO scans in many patients was performed months to years after initial diag- nosis and in many cases after systemic therapies which may have induced changes in tumor biology.
In 10% of patients positive lesions were visualized by [123I]IMTO, which had not been detected in CT. A frac- tion of the lesions (3/12) were seen outside the field of view of CT and therefore were not previously known. Other lesions seen in the bone, liver and the mesentery did not show pathological contrast enhancement or structural ab- normalities, but could be confirmed by follow-up exam- inations or other imaging modalities. However, in none of these cases treatment decisions were influenced by these findings.
An important question concerns the influence of mito- tane and cytotoxic chemotherapy on [123I]IMTO uptake in ACC lesions. Mitotane has been reported to interfere
with CYP11B1 activity (29), although direct binding to this enzyme has never been demonstrated. More recently, inhibition of CYP11B1 by mitotane has been questioned based on data from urinary steroid profiling in ACC (Chortis et al. under review). Based on our data no clear picture emerges, although current treatment with mito- tane was associated with a lower percentage of positive patients compared to a history of mitotane use (52.9 vs. 61.9%). Obviously, repeated imaging before and after reaching effective mitotane target plasma concentrations would be the best way to clarify this issue. Similarly, the impact of cytotoxic chemotherapy on [123I]IMTO uptake remains uncertain and consecutive imaging may also be required here to come to a clear answer.
The effect of systemic therapy on [123IJIMTO uptake is of high relevance in the context of radionuclide therapy [131I]IMTO. To qualify as a potential candidate for ra- dionuclide treatment with [131IJIMTO in the context of a clinical trial, all ACC lesions > 2 cm in a given patient should be uniformly positive in [123I]IMTO imaging. In the entire study population a relevant percentage of pa- tients (36.2%) qualified for such treatment and, in fact, 8 out of these 21 patients underwent [131IJIMTO treatment as reported previously (17). [13]]]IMTO therapy repre- sents the first molecular informed therapy of ACC as [123IJIMTO imaging allows appreciation of the expression of CYP11B enzymes in neoplastic tissue in the individual patient. Thus, currently a prospective phase II trial is un- derway to further evaluate this therapeutic option in ad- vanced ACC. In this context it is of interest that in treat- ment naïve patients 4 out of 5 positive patients (80.0%) qualified for [131IJIMTO therapy whereas in pretreated patients only 16 out of 29 positive patients (55.2%) did. This observation could indicate that treatment with [13]]]IMTO might be feasible more often early in the course of ACC and should not be delayed until increasing tumor cell heterogeneity precludes effective therapy.
According to our results, [123IJIMTO imaging may be of value in two different diagnostic settings in patients with ACC:
1. It can be used to evaluate a patient with ACC re- garding eligibility for enrollment in a clinical trial using [123IJIMTO for molecular informed targeted radionuclide therapy.
2. It helps in selected cases to noninvasively distinguish lesions of adrenocortical and nonadrenocortical origin (18).
Conclusion
[123I]IMTO allows visualization of recurrent and meta- static ACC in a substantial percentage of lesions and may
be particularly useful to demonstrate the adrenocortical origin in nonsecretory ACC lesions. The overall lesion based sensitivity and specificity was 38% and 100%, re- spectively. Furthermore, our study indicates that about one third of all ACC patients with metastastic disease show uptake of the radiotracer in all malignant lesions, which provides further support for the conduct of a pro- spective trial to determine if the first molecular informed therapy using [131IJIMTO will be of value to patients with metastatic ACC.
Acknowledgments
This work has been supported by the Wilhelm Sander Founda- tion (Grant No. 2003.175. to B.A., A.S. and S.H.) the IZKF Wuerzburg (Grant No. F-124 to S.H.and A.S.) and FP-7 WP06 ENSAT Cancer to B.A. S.H. is an awardee of the Else-Kröner- Fresenius Stiftung (Grant No. 2010 EKES.29). We also would like to thank Olga Schelkunov and Janina Schwind for their assistance.
Address all correspondence and requests for reprints to: Dr. med. Michael C. Kreissl, Department of Nuclear Medicine, Uni- versity Hospital of Wuerzburg, Oberduerrbacher Strasse 6, D-97080 Wuerzburg, Germany, Fax: +49-931-201-635000, Phone: +49-201-35000, e-mail: kreissl m@klinik.uni-wuerzburg.de.
* both authors contributed equally to this work Disclosure Summary: The authors have nothing to disclose This work was supported by .
References
1. Hahner S, Stuermer A, Kreissl M, Reiners C, Fassnacht M, Haens- cheid H, Beuschlein F, Zink M, Lang K, Allolio B, Schirbel A. [123 IJIodometomidate for molecular imaging of adrenocortical cyto- chrome P450 family 11B enzymes. J Clin Endocrinol Metab. 2008; 93:2358-2365.
2. Mitterhauser M, Wadsak W, Wabnegger L, Sieghart W, Viernstein H, Kletter K, Dudczak R. In vivo and in vitro evaluation of [18F]FETO with respect to the adrenocortical and GABAergic sys- tem in rats. Eur J Nucl Med Mol Imaging. 2003;30:1398-1401.
3. Zolle IM, Berger ML, Hammerschmidt F, Hahner S, Schirbel A, Peric-Simov B. New selective inhibitors of steroid 11beta-hydroxy- lation in the adrenal cortex. Synthesis and structure-activity rela- tionship of potent etomidate analogues. J Med Chem. 2008;51: 2244-2253.
4. Hennings J, Hellman P, Ahlstrom H, Sundin A. Computed tomog- raphy, magnetic resonance imaging and 11C-metomidate positron emission tomography for evaluation of adrenal incidentalomas. Eur J Radiol. 2009;69:314-323.
5. Hennings J, Lindhe O, Bergstrom M, Langstrom B, Sundin A, Hell- man P. [11C]metomidate positron emission tomography of adre- nocortical tumors in correlation with histopathological findings. J Clin Endocrinol Metab. 2006;91:1410-1414.
6. Minn H, Salonen A, Friberg J, Roivainen A, Viljanen T, Langsjo J, Salmi J, Valimaki M, Nagren K, Nuutila P. Imaging of adrenal in- cidentalomas with PET using (11)C-metomidate and (18)F-FDG. J Nucl Med. 2004;45:972-979.
7. Zettinig G, Mitterhauser M, Wadsak W, Becherer A, Pirich C, Vi- erhapper H, Niederle B, Dudczak R, Kletter K. Positron emission tomography imaging of adrenal masses: (18)F-fluorodeoxyglucose and the 11beta-hydroxylase tracer (11)C-metomidate. Eur J Nucl Med Mol Imaging. 2004;31:1224-1230.
8. Freitas JE, Grekin RJ, Thrall JH, Gross MD, Swanson DP, Beier- waltes WH. Adrenal imaging with iodomethyl-norcholesterol (I- 131) in primary aldosteronism. J Nucl Med. 1979;20:7-10.
9. Gordon L, Levine JH, Mayfield RK, Buse MG. Adrenal imaging with iodomethyl-norcholesterol (I-131) in primary aldosteronism. J Nucl Med. 1979;20:897-898.
10. Hwang I, Balingit AG, Georgitis WJ, Sisson JC, Shapiro B. Adre- nocortical SPECT using iodine-131 NP-59. J Nucl Med. 1998;39: 1460-1463.
11. La Cava G, Imperiale A, Olianti C, Gheri GR, Ladu C, Mannelli M, Pupi A. SPECT semiquantitative analysis of adrenocortical (131)I-6 beta iodomethyl-norcholesterol uptake to discriminate subclinical and preclinical functioning adrenal incidentaloma. J Nucl Med. 2003;44:1057-1064.
12. Maurea S, Imbriaco M, Mollica C, Pace L, Salvatore M. Quantita- tive imaging characterization of hypersecreting or nonhypersecret- ing adrenal adenomas: comparison between iodine-131 norcholes- terol uptake and magnetic resonance signal intensity ratios. Nucl Med Commun. 2011;32:535-541.
13. Maurea S, Klain M, Mainolfi C, Ziviello M, Salvatore M. The di- agnostic role of radionuclide imaging in evaluation of patients with nonhypersecreting adrenal masses. J Nucl Med. 2001;42:884-892.
14. Nocaudie-Calzada M, Huglo D, Lambert M, Ernst O, Proye C, Wemeau JL, Marchandise X. Efficacy of iodine-131 6beta-methyl- iodo-19-norcholesterol scintigraphy and computed tomography in patients with primary aldosteronism. Eur J Nucl Med. 1999;26: 1326-1332.
15. Wong KK, Komissarova M, Avram AM, Fig LM, Gross MD. Ad- renal cortical imaging with I-131 NP-59 SPECT-CT. Clin Nucl Med. 2010;35:865-869.
16. Khan TS, Sundin A, Juhlin C, Langstrom B, Bergstrom M, Eriksson B. 11C-metomidate PET imaging of adrenocortical cancer. Eur J Nucl Med Mol Imaging. 2003;30:403-410.
17. Hahner S, Kreissl MC, Fassnacht M, Haenscheid H, Knoedler P, Lang K, Buck AK, Reiners C, Allolio B, Schirbel A. [131I]Iodome- tomidate for Targeted Radionuclide Therapy of Advanced Adreno- cortical Carcinoma. J Clin Endocrinol Metab. 2012;97:914-922.
18. Hahner S, Kreissl MC, Fassnacht M, Haenscheid H, Bock S, Ver- burg FA, Knoedler P, Lang K, Reiners C, Buck AK, Allolio B, Schir- bel A. Functional Characterization of Adrenal Lesions Using [123I]IMTO-SPECT/CT. J Clin Endocrinol Metab.2013
19. Schirbel A, Zolle IM, Hammerschmidt F, Berger ML, Schiller D, Kvaternik H, Reiners C. [123/131I]Iodometomidate as a radioli- gand for functional diagnosis of adrenal disease: synthesis, struc- tural requirements and biodistribution. Radiochim Acta. 2004;92: 297-303.
20. Fassnacht M, Johanssen S, Fenske W, Weismann D, Agha A,
Beuschlein F, Fuhrer D, Jurowich C, Quinkler M, Petersenn S, Spahn M, Hahner S, Allolio B. Improved survival in patients with stage II adrenocortical carcinoma followed up prospectively by specialized centers. J Clin Endocrinol Metab. 2010;95:4925-4932.
21. Ansquer C, Scigliano S, Mirallie E, Taieb D, Brunaud L, Sebag F, Leux C, Drui D, Dupas B, Renaudin K, Kraeber-Bodere F. 18F-FDG PET/CT in the characterization and surgical decision concerning adrenal masses: a prospective multicentre evaluation. Eur J Nucl Med Mol Imaging. 2010;37:1669-1678.
22. Caoili EM, Korobkin M, Brown RK, Mackie G, Shulkin BL. Dif- ferentiating adrenal adenomas from nonadenomas using (18)F- FDG PET/CT: quantitative and qualitative evaluation. Acad Radiol. 2007;14:468-475.
23. Groussin L, Bonardel G, Silvera S, Tissier F, Coste J, Abiven G, Libe R, Bienvenu M, Alberini JL, Salenave S, Bouchard P, Bertherat J, Dousset B, Legmann P, Richard B, Foehrenbach H, Bertagna X, Tenenbaum F. 18F-Fluorodeoxyglucose positron emission tomog- raphy for the diagnosis of adrenocortical tumors: a prospective study in 77 operated patients. J Clin Endocrinol Metab. 2009;94: 1713-1722.
24. Leboulleux S, Dromain C, Bonniaud G, Auperin A, Caillou B, Lum- broso J, Sigal R, Baudin E, Schlumberger M. Diagnostic and prog- nostic value of 18-fluorodeoxyglucose positron emission tomogra- phy in adrenocortical carcinoma: a prospective comparison with computed tomography. J Clin Endocrinol Metab. 2006;91:920- 925.
25. Mackie GC, Shulkin BL, Ribeiro RC, Worden FP, Gauger PG, Mody RJ, Connolly LP, Kunter G, Rodriguez-Galindo C, Wallis JW, Hur- witz CA, Schteingart DE. Use of [18F]fluorodeoxyglucose positron emission tomography in evaluating locally recurrent and metastatic adrenocortical carcinoma. J Clin Endocrinol Metab. 2006;91: 2665-2671.
26. Rao SK, Caride VJ, Ponn R, Giakovis E, Lee SH. F-18 fluorode- oxyglucose positron emission tomography-positive benign adrenal cortical adenoma: imaging features and pathologic correlation. Clin Nucl Med. 2004;29:300-302.
27. Tenenbaum F, Groussin L, Foehrenbach H, Tissier F, Gouya H, Bertherat J, Dousset B, Legmann P, Richard B, Bertagna X. 18F- fluorodeoxyglucose positron emission tomography as a diagnostic tool for malignancy of adrenocortical tumours? Preliminary results in 13 consecutive patients. Eur J Endocrinol. 2004;150:789-792.
28. Gerlinger M, Rowan AJ, Horswell S, Larkin J, Endesfelder D, Gron- roos E, Martinez P, Matthews N, Stewart A, Tarpey P, Varela I, Phillimore B, Begum S, McDonald NQ, Butler A, Jones D, Raine K, Latimer C, Santos CR, Nohadani M, Eklund AC, Spencer-Dene B, Clark G, Pickering L, Stamp G, Gore M, Szallasi Z, Downward J, Futreal PA, Swanton C. Intratumor heterogeneity and branched evolution revealed by multiregion sequencing. N Engl J Med. 2012; 366:883-892.
29. Touitou Y, Moolenaar AJ, Bogdan A, Auzeby A, Luton JP. o,p’- DDD (mitotane) treatment for Cushing’s syndrome: adrenal drug concentration and inhibition in vitro of steroid synthesis. Eur J Clin Pharmacol. 1985;29:483-487.