Coming theses from other universities
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HER2-receptor quantification in breast cancer patients by imaging with ABY-025 Affibody and PET
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-517674
Breast cancer is the most common malignancy in women worldwide. Human epidermal growth factor receptor type 2 (HER2) is overexpressed in up to 20% of breast cancer cases and is considered an important prognostic factor and a therapeutic target. With the introduction of HER2-targeted therapy, it was important to recognize patients who will likely benefit from such treatment. Immunohistochemistry staining performed on a tumor biopsy, with in situ hybridization to detect gene amplification if needed, is the current gold standard method for HER2 receptor quantification. However, in cases with multiple metastases, it is both unfeasible and impractical to perform multiple biopsies without risking higher morbidity. Molecular imaging with tracers specifically targeting HER2 receptors provides a non-invasive approach, which allows full body quantification without the serious side effects associated with invasive biopsies. The molecule of focus in this thesis work is Affibody ZHER2:2891 (ABY-025) molecule that has a high affinity and selectivity towards HER2 receptors.
This thesis is based on four original articles. The first part focused on the aspect of breast cancer imaging using HER2-targeting gallium-labeled tracer 68Ga-ABY-025 in positron emission tomography (PET) and its role in predicting breast cancer outcome. The second part was to investigate the effect of different risk factors on developing brain metastasis, the overall survival and the effect of HER2-targeted treatment on breast cancer brain metastasis based on Uppsala County cancer registry.
We demonstrated that HER2-binding Affibody PET kinetics can be explained using a two-tissue compartment model and SUV values correlated well with the influx rates calculated using kinetic modeling, supporting its use to measure actual HER2 receptor binding. Phase II study demonstrated the potential of 68Ga-ABY-025 PET to predict the treatment outcome more accurately compared to biopsy HER2-status that uses the traditional immunohistochemistry staining and in situ hybridization techniques. 68Ga-ABY-025 PET provided accurate staging and reduced false positive 18F-FDG PET results in HER2-positive cases. HER2-positive molecular subtypes were associated with an increased risk of developing brain metastasis. Yet, longer survival times were observed in HER2-positive subtypes receiving HER2-targeted therapy.
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Surveillance and follow-up of early prostate cancer
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-515875
Active surveillance (AS) for prostate cancer was introduced to address overtreatment resulting from prostate-specific antigen (PSA) testing. Despite advancements such as Magnetic Resonance Imaging (MRI) and targeted biopsies, PSA remains crucial in prostate cancer diagnostics, leading to ongoing challenges of overdiagnosis and overtreatment. This thesis aimed to investigate different aspects of AS and follow-up of early prostate cancer and provide new insights to reduce overtreatment and enhance surveillance and follow-up. In Paper I, the rationale and methodology of a randomized controlled trial, the Prostate Cancer Active Surveillance Trigger trial/Scandinavian Prostate Cancer Group study no. 17 (PCASTt/SPCG17), were outlined. This trial's objective is to evaluate the safety of an AS protocol based on MRI and standardized triggers for repeat biopsies and transition to radical treatment. Patient recruitment is anticipated to conclude in 2024. Paper II investigated the risks of biochemical recurrence, metastatic disease, and prostate cancer-related death in patients following radical prostatectomy. The analysis was conditioned on time after radical prostatectomy without biochemical recurrence. For patients with favourable histopathology in prostatectomy specimens and no biochemical recurrence five years post-prostatectomy, the probability of developing metastatic disease or dying from prostate cancer within 20 years after surgery was very low. This suggests shorter follow-up for selected patients. Paper III compared outcomes of AS for men from different healthcare regions in Sweden with varying traditions of AS. Regions with lower uptake in AS demonstrated a higher probability of transitioning from AS to radical treatment, but no difference in AS failure. The results suggest overtreatment in regions with low uptake in AS. Paper IV explored the associations between potential triggers for transitioning from AS to radical treatment and the transition to treatment. We analysed how this association changed with the introduction of prostate MRI. We found an increasingly strong association between triggers, particularly histopathological progression, and transition. However, most treated men had not experienced histopathological progression. The introduction of MRI did not contribute much to the change. In conclusion, this thesis outlines an ongoing study on defined triggers for transitioning from AS to radical treatment, suggests shorter follow-up after radical prostatectomy for selected patients, reveals overtreatment in regions with low uptake in AS, and shows an increasing use of histopathological progression as a trigger for transition to radical treatment.
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Brain-gut-adipose interplay in the antidiabetic effects of gastric bypass surgery
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-517684
Gastric bypass surgery (GBP) leads not only to considerable and consistent weight loss but to a number of beneficial metabolic effects, often including a swift remission of type 2 diabetes (T2DM). Increases in the gut hormone GLP-1 are considered central to this effect, although several other mechanism are likely involved. One complication to GBP is post-bariatric hypoglycaemia (PBH), where the individual suffers from episodes of low blood sugar after meals. The mechanism behind this is incompletely understood.
Previous research has reported an attenuation of the counterregulatory response to hypoglycaemia in patients after GBP. Many hypoglycaemic episodes also appear to be asymptomatic. Together, this has led to the hypothesis that GBP and PBH may involve an adaptation to lower blood glucose levels, a lowered glycaemic set point. As much of hypoglycaemia counterregulation involves the central nervous system (CNS), such an adaptation would presumably involve neuroendocrine mechanism. Experimental treatment with GLP-1 receptor agonists (GLP-1RA) has been reported as successful against PBH, which is paradoxical as GLP-1RA stimulate insulin release.
The aim of this thesis is to further explore the metabolic changes after GBP that may influence glycaemic control. In Paper I, euglycaemic-hypoglycaemic clamps were used to assess whether infusion with GLP-1RA affects the counterregulatory response to hypoglycaemia after GBP. In Paper II, normoglycaemic-hypoglycaemic clamps were performed before and after GBP during simultaneous brain imaging with fMRI and FDG-PET techniques, cognitive testing and assessment of counterregulatory hormones. Paper III details the time course of metabolic changes after GBP in patients with previous T2DM with focus on adipose tissue, including gene expression, and possible anti-inflammatory effects. Paper IV approaches the same question as Paper I, this time in the setting of a standardized meal test. All papers include assessment of heart rate variability (HRV) as a potential reflection of autonomic nervous system (ANS) activity.
In Paper I, we do not find indications that GLP-1RA affects counterregulatory hormones, but that it may affect ANS activation during hypoglycaemia. In contrast, Paper IV reports higher cortisol levels with GLP1-RA after a meal, and indications of ANS effects, but no effect on post-prandial glucose levels. Results from Paper II support the hypothesis that GBP attenuates hormonal counterregulatory responses and affects how the CNS responds to hypoglycaemia. In Paper III we report sustained improvements in glucose uptake in adipocytes, potentially indications of decreased low-grade inflammation and signs of transient increases in parasympathetic activity.