Next generation radiotheranostics promoting precision medicine.

Radiotheranostics is a field of rapid growth with some approved treatments including 131I for thyroid cancer, 223Ra for osseous metastases, 177Lu-DOTATATE for neuroendocrine tumors, and 177Lu-PSMA (prostate-specific membrane antigen) for prostate cancer, and several more under investigation. In this review, we will cover the fundamentals of radiotheranostics, the key clinical studies that have led to current success, future developments with new targets, radionuclides and platforms, challenges with logistics and reimbursement and, lastly, forthcoming considerations regarding dosimetry, identifying the right line of therapy, artificial intelligence and more.

PSMA PET applications in the prostate cancer journey: from diagnosis to theranostics.

The heterogeneity of prostate cancer has made imaging modalities of crucial importance in this disease. Accurate diagnosis and staging of the volume and extent of disease, especially in advanced and metastatic prostate cancer, can help to tailor the timing and modalities of treatment. While MRI has been effective in the detection of significant prostate cancer, its use in the identification and quantification of extraprostatic disease is limited. This gap is now being filled by PSMA PET. PSMA PET scans have now been shown to have a role in all stages in the prostate cancer journey. Emerging evidence has shown its promise in primary staging, restaging and theranostics. In this paper, we review the evidence for the use of PSMA PET in the various stages of prostate cancer, from initial diagnosis to advanced metastatic disease where other systemic treatments have failed.

A pilot study of cardiopulmonary exercise testing and cardiac stress positron emission tomography before major non-cardiac surgery.

Cardiac events are a common cause of peri-operative morbidity. Cardiopulmonary exercise testing can objectively assess risk, but it does not quantify myocardial ischaemia. With appropriate dietary preparation to suppress basal myocardial glucose uptake, positron emission tomography with 18 F-fluorodeoxyglucose can identify post-ischaemic myocardium, providing an attractive complement to exercise testing. We aimed to investigate the feasibility of this diagnostic algorithm. Patients referred for cardiopulmonary exercise testing before major cancer surgery were prospectively recruited. Exercise testing and positron emission tomography imaging were performed after a high fat-low carbohydrate meal. Protocol feasibility (primary end-point) included compliance with pre-test diet instructions and the completion of tests. Stress myocardial perfusion imaging was performed if either exercise testing or positron emission tomography was equivocal or positive for ischaemia. We recorded cardiac complications for 30 postoperative days. We enrolled 26 participants, 20 of whom completed protocol. Twenty-one participants proceeded to surgery: myocardial injury or infarction was diagnosed in three participants, two of whom had positive or equivocal positron emission tomography but negative myocardial perfusion imaging. We have shown that pre-operative cardiac positron emission tomography after cardiopulmonary exercise testing is feasible; protocol deviations were minor and did not affect image quality. Our findings warrant further investigation to compare the diagnostic utility of cardiac positron emission tomography imaging with standard pre-operative stress tests.

Assessment of predictors of response and long-term survival of patients with neuroendocrine tumour treated with peptide receptor chemoradionuclide therapy (PRCRT).

PURPOSE: To review the response and outcomes of (177)Lu-DOTA-octreotate chemoradionuclide therapy (LuTate PRCRT) in patients with neuroendocrine tumour (NET) expressing high levels of somatostatin receptors with uncontrolled symptoms or disease progression. METHODS: A total of 68 patients (39 men; 17 - 76 years of age) who had completed an induction course of at least three cycles of LuTate PRCRT between January 2006 and June 2010 were reviewed. Ten patients were treated for uncontrolled symptoms and 58 had disease progression despite conventional treatment. The majority had four induction LuTate cycles (median treatment duration 5 months and cumulative activity 31 GBq), and 63 patients had concomitant 5-FU radiosensitizing infusional chemotherapy. Factors predicting overall survival were assessed using the log-rank test and Cox proportional hazards regression. RESULTS: Of those treated for uncontrolled symptoms, 70 % received benefit maintained for at least 6 months after treatment. Among patients with progressive disease 68 % showed stabilization or regression on CT, 67 % on molecular imaging and 56 % biochemically up to 12 months after treatment; 32 patients died. Overall survival rates at 2 and 5 year were 72.1 % and 52.1 %, respectively. Median overall survival was not estimable at a median follow-up of 60 months (range 5 - 86 months). Nonpancreatic primary sites, dominant liver metastases, lesion size <5 cm and the use of 5-FU chemotherapy were statistically significantly associated with objective response. A disseminated pattern and a high disease burden (whole-body retention index) were associated with an increased risk of death. Objective biochemical, molecular imaging and CT responses were all associated with longer overall survival. CONCLUSION: A high proportion of patients with progressive NET or uncontrolled symptoms received therapeutic benefit from LuTate with concomitant 5-FU chemotherapy. The achievement of objective biochemical, molecular or CT responses within 12 months was associated with improved overall survival. Patients with a primary pancreatic site and larger lesions (>5 cm) appeared to have lower objective response rates and may need a more aggressive treatment approach.

Limited role for surveillance PET-CT scanning in patients with diffuse large B-cell lymphoma in complete metabolic remission following primary therapy.

BACKGROUND: The usefulness of positron emission tomography with computed tomography (PET-CT) in the surveillance of patients with diffuse large B-cell lymphoma (DLBCL) in complete metabolic remission after primary therapy is not well studied. METHODS: We performed a retrospective review of our database between 2002 and 2009 for patients with de novo DLBCL who underwent surveillance PET-CT after achieving complete metabolic response (CMR) following primary therapy. RESULTS: Four-hundred and fifty scans were performed in 116 patients, with a median follow-up of 53 (range 8-133) months from completion of therapy. Thirteen patients (11%) relapsed: seven were suspected clinically and six were subclinical (all within first 18 months). The positive predictive value in patients with international prognostic index (IPI) <3 was 56% compared with 80% in patients with IPI ≥3. Including indeterminate scans, PET-CT retained high sensitivity 95% and specificity 97% for relapse. CONCLUSION: Positron emission tomography with computed tomography is not useful in patients for the majority of patients with diffuse large B-cell lymphoma in CMR after primary therapy, with the possible exception of patients with baseline IPI ≥3 in the 18 months following completion of primary therapy. This issue could be addressed by a prospective clinical trial.

Low-dose carboplatin modifies the tumor microenvironment to augment CAR T cell efficacy in human prostate cancer models.

Chimeric antigen receptor (CAR) T cells have transformed the treatment landscape for hematological malignancies. However, CAR T cells are less efficient against solid tumors, largely due to poor infiltration resulting from the immunosuppressive nature of the tumor microenvironment (TME). Here, we assessed the efficacy of Lewis Y antigen (LeY)-specific CAR T cells in patient-derived xenograft (PDX) models of prostate cancer. In vitro, LeY CAR T cells directly killed organoids derived from androgen receptor (AR)-positive or AR-null PDXs. In vivo, although LeY CAR T cells alone did not reduce tumor growth, a single prior dose of carboplatin reduced tumor burden. Carboplatin had a pro-inflammatory effect on the TME that facilitated early and durable CAR T cell infiltration, including an altered cancer-associated fibroblast phenotype, enhanced extracellular matrix degradation and re-oriented M1 macrophage differentiation. In a PDX less sensitive to carboplatin, CAR T cell infiltration was dampened; however, a reduction in tumor burden was still observed with increased T cell activation. These findings indicate that carboplatin improves the efficacy of CAR T cell treatment, with the extent of the response dependent on changes induced within the TME.

The potential for induction peptide receptor chemoradionuclide therapy to render inoperable pancreatic and duodenal neuroendocrine tumours resectable.

AIMS: To assess the clinical utility of peptide receptor chemoradionuclide therapy (PRCRT) using (177)Lu-octreotate (LuTate) with concurrent 5FU chemotherapy in patients with inoperable primary pancreatic and duodenal neuroendocrine tumours (NETs). METHODS: Between December 2006 and October 2009, five patients with progressive inoperable pancreatic and duodenal NETs without distant metastatic disease or with a potentially resectable solitary distant metastasis were treated with PRCRT; in combination with external beam radiotherapy in one case. Patients were followed up three months post-treatment with somatostatin receptor scintigraphy, radiology, biochemical markers and clinical assessment. Radiological response classification was defined by Response Evaluation Criteria in Solid Tumours (RECIST) with the addition of a minor response (MR; 10-30% size reduction) classification. Long-term follow up was performed until July 2011. RESULTS: At three months post-treatment, all five patients had a scintigraphic response, four had a radiological response and three of the four symptomatic patients responded clinically. All five patients had an ongoing treatment response beyond three months including one where further tumour shrinkage facilitated curative surgery. All five patients are alive with 12-42 months of follow-up post-treatment. CONCLUSION: PRCRT can be effective in inoperable pancreatic and duodenal neuroendocrine tumours and may play a role as neoadjuvant therapy in this patient group.

Imaging in follicular NHL.

Imaging contributes to management of follicular lymphoma (FL) through guiding biopsy, determining disease stage and assessing therapeutic response. Molecular imaging with positron emission tomography (PET), especially when combined with computer tomography (PET/CT), is more accurate than conventional imaging and extends the role of imaging to lesion characterisation, including non-invasive assessment of high-grade transformation. There is strong data to support the use of FDG PET/CT for primary staging, resulting in significant management change. In patients with early stage follicular lymphoma (stage I or II), there is a clear role for PET/CT to avoid futile involved-field radiotherapy in patients with widespread disease and to optimise the treatment field in patients with confirmed localised disease. For restaging, use of PET/CT allows discrimination between scar tissue and viable tumour in residual masses. Molecular imaging is likely to play an increasing role in selection of patients for specific treatments and in prognostic stratification.