Sir Peter MacCallum Department of Oncology - Research Publications
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ItemNo Preview AvailableFDG PET in the evaluation of immune-related hypophysitis and thyroiditis following combination ipilimumab and nivolumab in advanced melanoma(Society of Nuclear Medicine and Molecular Imaging, 2020-05-01)Objectives: Hypophysitis and thyroiditis are among the most commonly reported immune-related adverse events (irAEs) following combined ipilimumab/nivolumab therapy for melanoma. The role of 18F-FDG PET/CT (FDG-PET) in the evaluation of these endocrinopathies has not been systematically assessed. Methods: Between 2016 to 2019, all patients (pts) with advanced melanoma who received combined ipilimumab/nivolumab therapy were reviewed. Pts with a pre-treatment and post-treatment FDG-PET were included. On FDG-PET, PET-hypophysitis was defined as a discernable new uptake in the pituitary fossa and PET-thyroiditis as new diffuse uptake in the thyroid. Pre- and post-treatment SUVmax of pituitary and thyroid gland was measured. ROC analysis was used to derive the optimal threshold for metabolic changes on FDG-PET for distinguishing endocrinopathy. FDG-PET, clinical data and brain MRI were reviewed independently by a Nuclear Medicine physician, endocrinologist, and radiologist, respectively, and then findings were correlated. Results: Of 162 pts, 133 and 134 had assessable FDG-PET for hypophysitis and thyroiditis, respectively, with post-treatment FDG-PET performed at a median 76 days (IQR 52-83, range 18-225) from the start of immunotherapy. Overall 41/133 (29%) pts had PET-hypophysitis, of which 18 were clinically-confirmed, 3 were false-positive and 20 were not clinically-assessable due to receiving high-dose glucocorticoids for a concurrent irAE at the time of imaging, although 6 of these also had supportive contemporaneous MRI findings. For PET-hypophysitis pts, median pre- and post-treatment pituitary SUVmax were 2.7 (IQR 2.5-2.9, range 1.9-3.9) and 4.7 (IQR 3.6-5.5, range 2.6-16.2), with a percentage increase of 63% (IQR 39-94%, range 13-431%). The abnormal PET findings preceded the clinical diagnosis in 7/18 pts by a median of 16 days (range 5-50). FDG-PET was negative for hypophysitis in 12/29 pts with a prior or subsequent clinical diagnosis of hypophysitis. Where the clinical presentation was not masked by high-dose glucocorticoids, the positive and negative predictive value of FDG-PET for hypophysitis was 86% and 87%, respectively. Based on ROC analysis the optimal percentage change in SUVmax was 30% for distinguishing hypophysitis. PET-thyroiditis was detected in 30/134(22%) pts. The pre- and post-treatment SUVmax were 2.1 (IQR 1.7-2.3, range 1.3-3.3) and 4.8 (IQR 3.8-5.9, range 2.8-9.1), respectively, with an increase of 116% (IQR 84-177%, range 52-300%). Overall 41/134 (31%) pts had documented biochemical evidence of thyroiditis. The positive and negative predictive value of PET was 97% and 89%, respectively. Based on ROC analysis, the optimal percentage change in SUVmax for distinguishing thyroiditis was 42%. Further follow-up FDG-PET (30/39 pts with PET-hypophysitis and 25/30 pts with PET-thyroiditis) revealed resolution of SUVmax to baseline in all cases by a median of 104 days (IQR 77-133, range 40-484) and 32 days (IQR 79-194, range 49-1045), respectively. Conclusions: FDG-PET detects transient increases in FDG uptake in the pituitary and thyroid gland following combined ipilimumab/nivolumab which appears to be highly predictive of the development of these endocrinopathies, therefore prompting more stringent monitoring. A high incidence of uninterpretable biochemical assessment of the pituitary-adrenal axis likely contributed to the underestimation of hypophysitis incidence. A multimodality approach is important in the timely diagnosis of immune-related endocrinopathies.
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ItemNo Preview AvailableOpportunistic Assessment of Pituitary Gland with Routine MRI and PET/CT Can Guide in Earlier and Increased Identification of Hypophysitis in Patients Treated with Combination Checkpoint Inhibitors(The Endocrine Society, 2020-05-08)Background: Hypophysitis is one of the commonly reported adverse events related to immune checkpoint inhibitors (ICI), and the incidence is expected to rise with increased use of combined programmed cell death protein 1 (PD1) and cytotoxic T lymphocyte associated protein 4 (CTLA4) blockade. The clinical diagnosis can be delayed due to non-specific symptoms. At our centre, subjects undergo periodic imaging to assess tumour response to ICI. We reviewed whether neuroimaging studies can guide us in the diagnosis of hypophysitis and whether early changes can be detected before the onset of the clinical syndrome. Methods: We retrospectively reviewed the medical charts, biochemistry, structural brain imaging and whole-body positron emission tomography (PET) with specific reference to hypophysitis in 162 patients treated with combination ICI at a tertiary melanoma referral centre. Suspected cases were identified based on meeting one or more of the following criteria: 1) A documented diagnosis of hypophysitis or pituitary dysfunction found on chart review, 2) A relative change in pituitary size or appearance from baseline on neuroimaging studies, or 3) An increase in pituitary maximum standardized uptake value (SUVmax) greater than 25% from baseline on 18F-FDG PET. Results: 58/162 patients (36%) met criteria for suspected hypophysitis. Only 4 patients were identified on routine screening of early morning cortisol. 14 patients presented with symptoms leading to biochemical work up. A further 40 patients were found to have suspicious imaging changes, 13 of which went on to receive a formal diagnosis of hypophysitis. Of the remaining 27 patients, 23 were receiving high dose glucocorticoids for concomitant immune related adverse events at the time of the abnormal imaging study.Conclusion: We report the highest incidence to date of suspected hypophysitis in cohort of patients treated with combination ICI. This study highlights the important role of structural and functional neuroimaging in the early recognition of hypophysitis. Imaging may also play a role when the clinical syndrome is masked by concurrent glucocorticoid use.
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ItemImaging for assessment of cancer treatment response to immune checkpoint inhibitors can be complementary in identifying hypophysitis(FRONTIERS MEDIA SA, 2023-11-29)INTRODUCTION: Hypophysitis is reported in 8.5%-14% of patients receiving combination immune checkpoint inhibition (cICI) but can be a diagnostic challenge. This study aimed to assess the role of routine diagnostic imaging performed during therapeutic monitoring of combination anti-CTLA-4/anti-PD-1 treatment in the identification of hypophysitis and the relationship of imaging findings to clinical diagnostic criteria. METHODS: This retrospective cohort study identified patients treated with cICI between January 2016 and January 2019 at a quaternary melanoma service. Medical records were reviewed to identify patients with a documented diagnosis of hypophysitis based on clinical criteria. Available structural brain imaging with magnetic resonance imaging (MRI) or computed tomography (CT) of the brain and 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography with computed tomography (FDG-PET/CT) were assessed retrospectively. The main radiological outcome measures were a relative change in pituitary size or FDG uptake temporally attributed to cICI. RESULTS: There were 162 patients (median age 60 years, 30% female) included. A total of 100 and 134 had serial CT/MRI of the brain and FDG-PET/CT, respectively. There were 31 patients who had a documented diagnosis of hypophysitis and an additional 20 who had isolated pituitary imaging findings. The pituitary gland enlargement was mild, and the largest absolute gland size was 13 mm, with a relative increase of 7 mm from baseline. There were no cases of optic chiasm compression. Pituitary enlargement and increased FDG uptake were universally transient. High-dose glucocorticoid treatment for concurrent irAEs prevented assessment of the pituitary-adrenal axis in 90% of patients with isolated imaging findings. CONCLUSION: Careful review of changes in pituitary characteristics on imaging performed for assessment of therapeutic response to iICI may lead to increased identification and more prompt management of cICI-induced hypophysitis.
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ItemIncreased Thyroidal Activity on Routine FDG-PET/CT after Combination Immune Checkpoint Inhibition: Temporal Associations with Clinical and Biochemical Thyroiditis(MDPI, 2023-12)BACKGROUND: FDG-PET/CT used for immune checkpoint inhibitor (ICI) response assessment can incidentally identify immune-related adverse events (irAEs), including thyroiditis. This study aimed to correlate the time course of FDG-PET/CT evidence of thyroiditis with clinical and biochemical evolution of thyroid dysfunction. METHODS: A retrospective review was performed by two independent blinded nuclear medicine physicians (NMPs) of thyroidal FDG uptake in 127 patients who underwent PET/CT between January 2016 and January 2019 at baseline and during treatment monitoring of combination ICI therapy for advanced melanoma. Interobserver agreement was assessed and FDG-PET/CT performance defined by a receiver-operating characteristic (ROC) curve using thyroid function tests (TFTs) as the standard of truth. Thyroid maximum standardized uptake value (SUVmax) and its temporal changes with respect to the longitudinal biochemistry were serially recorded. RESULTS: At a median of 3 weeks after commencing ICI, 43/127 (34%) had a diagnosis of thyroiditis established by abnormal TFTs. FDG-PET/CT was performed at baseline and at a median of 11 weeks (range 3-32) following the start of therapy. ROC analysis showed an area under the curve of 0.87 (95% CI 0.80, 0.94) for FDG-PET/CT for detection of thyroiditis with a positive predictive value of 93%. Among patients with biochemical evidence of thyroiditis, those with a positive FDG-PET/CT were more likely to develop overt hypothyroidism (77% versus 35%, p < 0.01). In the evaluation of the index test, there was an almost perfect interobserver agreement between NMPs of 93.7% (95% CI 89.4-98.0), kappa 0.83. CONCLUSION: Increased metabolic activity of the thyroid on routine FDG-PET/CT performed for tumoral response of patients undergoing ICI therapy is generally detected well after routine biochemical diagnosis. Elevation of FDG uptake in the thyroid is predictive of overt clinical hypothyroidism and suggests that an ongoing robust inflammatory response beyond the initial thyrotoxic phase may be indicative of thyroid destruction.
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ItemClinical validation and implementation of droplet digital PCR for the detection of BRAF mutations from cell-free DNA(ELSEVIER, 2022-10)Droplet digital PCR (ddPCR) has been demonstrated in many research studies to be a sensitive method in the analysis of circulating tumour DNA (ctDNA) for identifying mutations and tracking disease. The transition of ddPCR into the diagnostic setting requires a number of critical steps including the assessment of accuracy and precision and ultimately implementation into clinical use. Here we present the clinical validation of ddPCR for the detection of BRAF mutations (V600E and V600K) from plasma. We describe the performance characteristics assessed including the limit of blank, limit of detection, ruggedness, accuracy, precision and the effect of the matrix. Overall, each assay could achieve a limit of detection of 0.5% variant allele fraction and was highly accurate, with 100% concordance of results obtained from routine diagnostic testing of formalin fixed tumour samples or reference controls (n=36 for BRAF V600E and n=30 for BRAF V600K). Inter-laboratory reproducibility across 12 plasma samples for each assay was also assessed and results were 100% concordant. Overall, we report the successful validation and translation of a ddPCR assay into clinical routine practice.
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ItemPrognostic and predictive value of β-blockers in the EORTC 1325/KEYNOTE-054 phase III trial of pembrolizumab versus placebo in resected high-risk stage III melanoma(ELSEVIER SCI LTD, 2022-04)BACKGROUND: β-adrenergic receptors are upregulated in melanoma cells and contribute to an immunosuppressive, pro-tumorigenic microenvironment. This study investigated the prognostic and predictive value of β-adrenoreceptor blockade by β-blockers in the EORTC1325/KEYNOTE-054 randomised controlled trial. METHODS: Patients with resected stage IIIA, IIIB or IIIC melanoma and regional lymphadenectomy received 200 mg of adjuvant pembrolizumab (n = 514) or placebo (n = 505) every three weeks for one year or until recurrence or unacceptable toxicity. At a median follow-up of 3 years, pembrolizumab prolonged recurrence-free survival (RFS) compared to placebo (hazard ratio (HR) 0.56, 95% confidence interval (CI) 0.47-0.68). β-blocker use was defined as oral administration of any β-blocker within 30 days of randomisation. A multivariable Cox proportional hazard model was used to estimate the HR for the association between the use of β-blockers and RFS. RESULTS: Ninety-nine (10%) of 1019 randomised patients used β-blockers at baseline. β-blockers had no independent prognostic effect on RFS: HR 0.96 (95% CI 0.70-1.31). The HRs of RFS associated with β-blocker use were 0.67 (95% CI 0.38-1.19) in the pembrolizumab arm and 1.15 (95% CI 0.80-1.66) in the placebo arm. The HR of RFS associated with pembrolizumab compared to placebo was 0.34 (95% CI 0.18-0.65) among β-blocker users and 0.59 (95% CI 0.48-0.71) among those not using β-blockers. CONCLUSIONS: This study suggests no prognostic effect of β-blockers in resected high-risk stage III melanoma. However, β-blockers may predict improved efficacy of adjuvant pembrolizumab treatment. The combination of immunotherapy with β-blockers merits further investigation. This study is registered with ClinicalTrials.gov, NCT02362594, and EudraCT, 2014-004944-37.
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ItemModelling aggressive prostate cancers of young men in immune-competent mice, driven by isogenic Trp53 alterations and Pten loss(SPRINGERNATURE, 2022-09-08)Understanding prostate cancer onset and progression in order to rationally treat this disease has been critically limited by a dire lack of relevant pre-clinical animal models. We have generated a set of genetically engineered mice that mimic human prostate cancer, initiated from the gland epithelia. We chose driver gene mutations that are specifically relevant to cancers of young men, where aggressive disease poses accentuated survival risks. An outstanding advantage of our models are their intact repertoires of immune cells. These mice provide invaluable insight into the importance of immune responses in prostate cancer and offer scope for studying treatments, including immunotherapies. Our prostate cancer models strongly support the role of tumour suppressor p53 in functioning to critically restrain the emergence of cancer pathways that drive cell cycle progression; alter metabolism and vasculature to fuel tumour growth; and mediate epithelial to mesenchymal-transition, as vital to invasion. Importantly, we also discovered that the type of p53 alteration dictates the specific immune cell profiles most significantly disrupted, in a temporal manner, with ramifications for disease progression. These new orthotopic mouse models demonstrate that each of the isogenic hotspot p53 amino acid mutations studied (R172H and R245W, the mouse equivalents of human R175H and R248W respectively), drive unique cellular changes affecting pathways of proliferation and immunity. Our findings support the hypothesis that individual p53 mutations confer their own particular oncogenic gain of function in prostate cancer.
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ItemTargeting MDM4 as a Novel Therapeutic Approach in Prostate Cancer Independent of p53 Status(MDPI, 2022-08)Metastatic prostate cancer is a lethal disease in patients incapable of responding to therapeutic interventions. Invasive prostate cancer spread is caused by failure of the normal anti-cancer defense systems that are controlled by the tumour suppressor protein, p53. Upon mutation, p53 malfunctions. Therapeutic strategies to directly re-empower the growth-restrictive capacities of p53 in cancers have largely been unsuccessful, frequently because of a failure to discriminate responses in diseased and healthy tissues. Our studies sought alternative prostate cancer drivers, intending to uncover new treatment targets. We discovered the oncogenic potency of MDM4 in prostate cancer cells, both in the presence and absence of p53 and also its mutation. We uncovered that sustained depletion of MDM4 is growth inhibitory in prostate cancer cells, involving either apoptosis or senescence, depending on the cell and genetic context. We identified that the potency of MDM4 targeting could be potentiated in prostate cancers with mutant p53 through the addition of a first-in-class small molecule drug that was selected as a p53 reactivator and has the capacity to elevate oxidative stress in cancer cells to drive their death.
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ItemTumor immune microenvironment of primary prostate cancer with and without germline mutations in homologous recombination repair genes(BMJ PUBLISHING GROUP, 2022-06)BACKGROUND: Aberrations in homologous recombination repair (HRR) genes are emerging as important biomarkers for personalized treatment in prostate cancer (PCa). HRR deficiency (HRD) could affect the tumor immune microenvironment (TIME), potentially contributing to differential responses to poly ADP-ribose polymerase (PARP) inhibitors and immune checkpoint inhibitors. Spatial distribution of immune cells in a range of cancers identifies novel disease subtypes and is related to prognosis. In this study we aimed to determine the differences in the TIME of PCa with and without germline (g) HRR mutations. METHODS: We performed gene expression analysis, multiplex immunohistochemistry of T and B cells and quantitative spatial analysis of PCa samples from 36 patients with gHRD and 26 patients with sporadic PCa. Samples were archival tumor tissue from radical prostatectomies with the exception of one biopsy. Results were validated in several independent cohorts. RESULTS: Although the composition of the T cell and B cells was similar in the tumor areas of gHRD-mutated and sporadic tumors, the spatial profiles differed between these cohorts. We describe two T-cell spatial profiles across primary PCa, a clustered immune spatial (CIS) profile characterized by dense clusters of CD4+ T cells closely interacting with PD-L1+ cells, and a free immune spatial (FIS) profile of CD8+ cells in close proximity to tumor cells. gHRD tumors had a more T-cell inflamed microenvironment than sporadic tumors. The CIS profile was mainly observed in sporadic tumors, whereas a FIS profile was enriched in gHRD tumors. A FIS profile was associated with lower Gleason scores, smaller tumors and longer time to biochemical recurrence and metastasis. CONCLUSIONS: gHRD-mutated tumors have a distinct immune microenvironment compared with sporadic tumors. Spatial profiling of T-cells provides additional information beyond T-cell density and is associated with time to biochemical recurrence, time to metastasis, tumor size and Gleason scores.
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ItemTargeting wild-type TP53 using AMG 232 in combination with MAPK inhibition in Metastatic Melanoma; a phase 1 study(SPRINGER, 2022-10)BACKGROUND: Targeting the MDM2-p53 interaction using AMG 232 is synergistic with MAPK inhibitors (MAPKi) in preclinical melanoma models. We postulated that AMG 232 plus MAPKi is safe and more effective than MAPKi alone in TP53-wild type, MAPKi-naïve metastatic melanoma. METHODS: Patients were treated with increasing (120 mg, 180 mg, 240 mg) oral doses of AMG 232 (seven-days-on, 15-days-off, 21-day cycle) plus dabrafenib (D) and trametinib (T) (Arm 1, BRAFV600-mutant) or T alone (Arm 2, BRAFV600-wild type). Patients were treated for seven days with AMG 232 alone before adding T±D. Safety and efficacy were assessed using CTCAE v4.0 and RECIST v1.1 criteria, respectively. Pharmacokinetic (PK) analysis was performed at baseline and steady-state levels for AMG 232. RESULTS: 31 patients were enrolled. Ten and 21 patients were enrolled in Arm 1 and Arm 2, respectively. The most common AMG 232-related adverse events (AEs) were nausea (87%), diarrhea (77%), and fatigue (74%). Seven patients (23%) were withdrawn from the study due to AMG 232-related AEs. Three dose-limiting AEs occurred (Arm 1, 180 mg, nausea; Arm 2, 240 mg, grade 3 pulmonary embolism; Arm 2, 180 mg, grade 4 thrombocytopenia). AMG 232 PK exposures were not altered when AMG 232 was combined with T±D. Objective responses were seen in 8/10 (Arm 1) and 3/20 (Arm 2) evaluable patients. The median progression-free survival for Arm 1 and Arm 2 was 19.0 months-not reached and 2.8 months, respectively. CONCLUSION: The maximum tolerated dose of AMG 232 for both arms was 120 mg. AMG 232 plus T±D exhibited a favorable PK profile. Although objective responses occurred in both arms, adding AMG 232 to T±D did not confer additional clinical benefit.