Assessment of hypoxic subvolumes in laryngeal cancer with (18)F-fluoroazomycinarabinoside ((18)F-FAZA)-PET/CT scanning and immunohistochemistry

Hypoxia-specific imaging in patients with lymphoma undergoing CAR-T therapy

PURPOSE

Intratumoral hypoxia in non-Hodgkin's Lymphoma (NHL) may interfere with chimeric antigen receptor T-cell (CAR-T) function. We conducted a single-center pilot study (clinicaltrials.gov ID NCT04409314) of [18F]fluoroazomycin arabinoside, a hypoxia-specific radiotracer abbreviated as [18F]FAZA, to assess the feasibility of this positron emission tomography (PET) imaging modality in this population.

METHODS

Patients with relapsed NHL being evaluated for CAR-T therapy received a one-time [18F]FAZA PET scan before pre-CAR-T lymphodepletion. A tumor to mediastinum (T/M) ratio of 1.2 or higher with regard to [18F]FAZA uptake was defined as positive for intratumoral hypoxia. We planned to enroll 30 patients with an interim futility analysis after 16 scans.

RESULTS

Of 16 scanned patients, 3 had no evidence of disease by standard [18F]fluorodeoxyglucose PET imaging before CAR-T therapy. Six patients (38%) had any [18F]FAZA uptake above background. Using a T/M cutoff of 1.20, only one patient (a 68-year-old male with relapsed diffuse large B-cell lymphoma) demonstrated intratumoral hypoxia in an extranodal chest wall lesion (T/M 1.35). Interestingly, of all 16 scanned patients, he was the only patient with progressive disease within 1 month of CAR-T therapy. However, because of our low overall proportion of positive scans, our study was stopped for futility.

CONCLUSIONS

Our pilot study identified low-level [18F]FAZA uptake in a small number of patients with NHL receiving CAR-T therapy. The only patient who met our pre-specified threshold for intratumoral hypoxia was also the only patient with early CAR-T failure. Future plans include exploration of [18F]FAZA in a more selected patient population.

First Comparison between [18f]-FMISO and [18f]-Faza for Preoperative Pet Imaging of Hypoxia in Lung Cancer

Simple Summary

The definition of the tumor hypoxia is important in oncology because this characteristic is linked to a poor prognosis. In this context, we compared two hypoxia tracers, FMISO and FAZA, before surgery for lung cancer. Hypoxia tracers correlate well with each other and FMISO is superior to FAZA in defining the hypoxia volume of lung cancers. However, there is no correlation with immunohistochemical findings (GLUT-1, CAIX, LDH-5, and HIF1-Alpha).

Abstract

Hypoxic areas are typically resistant to treatment. However, the fluorine-18-fluoroazomycin-arabinoside (FAZA) and fluorine 18 misonidazole (FMISO) tracers have never been compared in non small cell lung cancer (NSCLC). This study compares the capability of 18F-FAZA PET/CT with that of 18F-FMISO PET/CT for detecting hypoxic tumour regions in early and locally advanced NSCLC patients. We prospectively evaluated patients who underwent preoperative PET scans before surgery for localised NSCLC (i.e., fluorodeoxyglucose (FDG)-PET, FMISO-PET, and FAZA-PET). The PET data of the three tracers were compared with each other and then compared to immunohistochemical analysis (GLUT-1, CAIX, LDH-5, and HIF1-Alpha) after tumour resection. Overall, 19 patients with a mean age of 68.2 ± 8 years were included. There were 18 lesions with significant uptake (i.e., SUVmax >1.4) for the F-MISO and 17 for FAZA. The mean SUVmax was 3 (±1.4) with a mean volume of 25.8 cc (±25.8) for FMISO and 2.2 (±0.7) with a mean volume of 13.06 cc (±13.76) for FAZA. The SUVmax of F-MISO was greater than that of FAZA (p = 0.0003). The SUVmax of F-MISO shows a good correlation with that of FAZA at 0.86 (0.66–0.94). Immunohistochemical results are not correlated to hypoxia PET regardless of the staining. The two tracers show a good correlation with hypoxia, with FMISO being superior to FAZA. FMISO, therefore, remains the reference tracer for defining hypoxic volumes.

Non-FDG PET/CT in Diagnostic Oncology: a pictorial review

Positron emission tomography/computed tomography (PET/CT) is currently one of the main imaging modalities for cancer patients worldwide. Fluorodeoxyglucose (FDG) PET/CT has earned its global recognition in the modern management of cancer patients and is rapidly becoming an important imaging modality for patients with cardiac, neurological, and infectious/inflammatory conditions.

Despite its proven benefits, FDG has limitations in the assessment of several relevant tumours such as prostate cancer. Therefore, there has been a pressing need for the development and clinical application of different PET radiopharmaceuticals that could image these tumours more precisely. Accordingly, several non-FDG PET radiopharmaceuticals have been introduced into the clinical arena for management of cancer. This trend will undoubtedly continue to spread internationally. The use of PET/CT with different PET radiopharmaceuticals specific to tumour type and biological process being assessed is part of the personalised precision medicine approach.

The objective of this publication is to provide a case-based method of understanding normal biodistribution, variants, and pitfalls, including several examples of different imaging appearances for the main oncological indications for each of the new non-FDG PET radiopharmaceuticals. This should facilitate the interpretation and recognition of common variants and pitfalls to ensure that, in clinical practice, the official report is accurate and helpful.

Some of these radiopharmaceuticals are already commercially available in many countries (e.g. ⁶⁸Ga-DOTATATE and DOTATOC), others are in the process of becoming available (e.g. ⁶⁸Ga-PSMA), and some are still being researched. However, this list is subject to change as some radiopharmaceuticals are increasingly utilised, while others gradually decrease in use.

Mechanism-Specific Pharmacodynamics of a Novel Complex-I Inhibitor Quantified by Imaging Reversal of Consumptive Hypoxia with [18F]FAZA PET In Vivo

Tumors lack a well-regulated vascular supply of O₂ and often fail to balance O₂ supply and demand. Net O₂ tension within many tumors may not only depend on O₂ delivery but also depend strongly on O₂ demand. Thus, tumor O₂ consumption rates may influence tumor hypoxia up to true anoxia. Recent reports have shown that many human tumors in vivo depend primarily on oxidative phosphorylation (OxPhos), not glycolysis, for energy generation, providing a driver for consumptive hypoxia and an exploitable vulnerability. In this regard, IACS-010759 is a novel high affinity inhibitor of OxPhos targeting mitochondrial complex-I that has recently completed a Phase-I clinical trial in leukemia. However, in solid tumors, the effective translation of OxPhos inhibitors requires methods to monitor pharmacodynamics in vivo. Herein, ¹⁸F-fluoroazomycin arabinoside ([¹⁸F]FAZA), a 2-nitroimidazole-based hypoxia PET imaging agent, was combined with a rigorous test-retest imaging method for non-invasive quantification of the reversal of consumptive hypoxia in vivo as a mechanism-specific pharmacodynamic (PD) biomarker of target engagement for IACS-010759. Neither cell death nor loss of perfusion could account for the IACS-010759-induced decrease in [¹⁸F]FAZA retention. Notably, in an OxPhos-reliant melanoma tumor, a titration curve using [¹⁸F]FAZA PET retention in vivo yielded an IC₅₀ for IACS-010759 (1.4 mg/kg) equivalent to analysis ex vivo. Pilot [¹⁸F]FAZA PET scans of a patient with grade IV glioblastoma yielded highly reproducible, high-contrast images of hypoxia in vivo as validated by CA-IX and GLUT-1 IHC ex vivo. Thus, [¹⁸F]FAZA PET imaging provided direct evidence for the presence of consumptive hypoxia in vivo, the capacity for targeted reversal of consumptive hypoxia through the inhibition of OxPhos, and a highly-coupled mechanism-specific PD biomarker ready for translation.

Roles of GLUT-1 and HK-II expression in the biological behavior of head and neck cancer

The Warburg effect plays an important role in the proliferation and invasion of malignant tumors. Glucose transporter 1 and hexokinase II are two key energy transporters involved in mediating the Warburg effect. This review will analyze the mechanisms of these two markers in their effects on the biological behavior of head and neck cancer.

Prognostic value of dynamic hypoxia PET in head and neck cancer: Results from a planned interim analysis of a randomized phase II hypoxia-image guided dose escalation trial

BACKGROUND AND PURPOSE

To prospectively assess the prognostic value of tumour hypoxia determined by dynamic [¹⁸F]Fluoromisonidazole (dynFMISO) PET/CT, and to evaluate both feasibility and toxicity in patients with locally advanced squamous cell carcinomas of the head and neck (LASCCHN) treated with dynFMISO image-guided dose escalation (DE) using dose-painting by contours.

PATIENTS AND METHODS

We present a planned interim analysis of a randomized phase II trial. N=25 patients with LASCCHN received baseline dynFMISO PET/CT to derive hypoxic volumes (HV). Patients with tumour hypoxia were randomized into standard radiochemotherapy (stdRT) (70Gy/35 fractions) or DE (77Gy/35 fractions) to the HV. Patients with non-hypoxic tumours were treated with stdRT. Loco-regional control (LRC) in hypoxic patients randomized to stdRT was compared to non-hypoxic patients. Feasibility and toxicity were analysed for patients in the DE arm and compared to stdRT.

RESULTS

With a mean follow-up of 27months, LRC in hypoxic patients receiving stdRT (n=10) was significantly worse compared to the non-hypoxic group (n=5) (2y-LRC 44.4% versus 100%, p=0.048). The respective LRC for the DE group (n=10) was 70.0%. Treatment compliance as well as acute and late toxicity did not show significant differences between the DE and the standard dose arms.

CONCLUSION

Tumour hypoxia determined by baseline dynFMISO PET/CT is associated with a high risk of local failure in patients with LASCCHN. First data suggest that DE to HV is feasible without excess toxicity.

Current relevance of hypoxia in head and neck cancer

Head and Neck cancer (HNC) is a complex mix of cancers and one of the more common cancers with a relatively poor prognosis. One of the factors that may assist us in predicting survival and allow us to adjust our treatment strategies is the presence of tumor hypoxia. In this overview we aim to evaluate the current evidence and potential clinical relevance of tumor hypoxia in head and neck cancer according to an extensive search of current literature.An abundance of evidence and often contradictory evidence is found in the literature. Even the contradictory evidence and comparisons are difficult to judge as criteria and methodologies differ greatly, furthermore few prospective observational studies exist for verification of the pre-clinical studies. Despite these discrepancies there is clear evidence of associations between prognosis and poor tumor oxygenation biomarkers such as HIF-1α, GLUT-1 and lactate, though these associations are not exclusive. The use of genetic markers is expanding and will probably lead to significantly more and complex evidence. The lack of oxygenation in head and neck tumors is of paramount importance for the prediction of treatment outcomes and prognosis. Despite the wide array of conflicting evidence, the drive towards non-invasive prediction of tumor hypoxia should continue.