TG01/GM-CSF and adjuvant gemcitabine in patients with resected RAS-mutant adenocarcinoma of the pancreas (CT TG01-01): a single-arm, phase 1/2 trial.

BACKGROUND: TG01 is the first cancer immunotherapy targeting KRAS oncogenic mutations. This study assessed the safety and efficacy of TG01/GM-CSF in patients with resected pancreatic adenocarcinoma. METHODS: Patients with stage I or II pancreatic adenocarcinoma who had undergone surgical resection (R0 or R1) received adjuvant gemcitabine with TG01/GM-CSF using two schedules of vaccination. Immune response was defined as a positive delayed-type hypersensitivity (DTH) response and/or positive T-cell proliferation assay. RESULTS: Thirty-two patients were enrolled between February 2013 and May 2016. Nineteen were treated with the high antigen burden, with four serious adverse reactions considered possibly related to TG01 treatment, including three allergic reactions. On this basis, a further 13 patients received a modified vaccination schedule with reduced antigen burden, with no serious adverse events related to TG01. Ninety-five percent patients in the main cohort and 92% in the modified cohort had a positive immune response. Median overall survival (OS) was 33.1 months, and median disease-free survival (DFS) was 13.9 months for the main cohort. For the modified cohort, the median OS was 34.3 months and median DFS was 19.5 months. CONCLUSIONS: TG01/GM-CSF with gemcitabine was well tolerated, with high levels of immune activation. OS and DFS compare favourably with published data for adjuvant gemcitabine. CLINICAL TRIAL REGISTRATION: This clinical trial was registered at ClinicalTrials.gov (NCT02261714).

Efficacy and safety of radium-223 dichloride in patients with castration-resistant prostate cancer and symptomatic bone metastases, with or without previous docetaxel use: a prespecified subgroup analysis from the randomised, double-blind, phase 3 ALSYMPCA trial.

BACKGROUND: Primary results from the phase 3 ALSYMPCA trial showed that radium-223 dichloride (radium-223), a targeted α-emitter, improved overall survival compared with placebo and was well tolerated in patients with castration-resistant prostate cancer and symptomatic bone metastases. We did a prespecified subgroup analysis from ALSYMPCA to assess the effect of previous docetaxel use on the efficacy and safety of radium-223. METHODS: In the phase 3, randomised, double-blind ALSYMPCA trial, patients with symptomatic castration-resistant prostate cancer, at least two symptomatic bone metastases, no known visceral metastases, and who were receiving best standard of care were randomly assigned (2:1) via an interactive voice response system to receive six injections of radium-223 (50 kBq/kg intravenously) or matching placebo, with one injection given every 4 weeks. Patients had either received previous docetaxel treatment or were unsuitable for or declined docetaxel; previous docetaxel use (yes or no) was a trial stratification factor. We investigated the effect of previous docetaxel use on radium-223 treatment for the primary endpoint of overall survival, the main secondary efficacy endpoints, and safety. Efficacy analyses were done for the intention-to-treat population; safety analyses were done for the safety population. The trial has been completed and is registered with ClinicalTrials.gov, number NCT00699751. FINDINGS: Randomisation took place between June 12, 2008, and Feb 1, 2011. 526 (57%) of 921 randomly assigned patients had received previous docetaxel treatment (352 in the radium-223 group and 174 in the placebo group) and 395 (43%) had not (262 in the radium-223 group and 133 in the placebo group). Radium-223 prolonged median overall survival compared with placebo, irrespective of previous docetaxel use (previous docetaxel use, hazard ratio [HR] 0·70, 95% CI 0·56-0·88; p=0·002; no previous docetaxel use, HR 0·69, 0·52-0·92; p=0·01). The benefit of radium-223 compared with placebo was seen in both docetaxel subgroups for most main secondary efficacy endpoints; risk for time to time to first symptomatic skeletal event was reduced with radium-223 versus placebo in patients with previous docetaxel use, but the difference was not significant in those with no previous docetaxel use. 322 (62%) of 518 patients previously treated with docetaxel had grade 3-4 adverse events, compared with 205 (54%) of 383 patients without docetaxel. Patients who had previously been treated with docetaxel had a higher incidence of grade 3-4 thrombocytopenia with radium-223 than with placebo (31 [9%] of 347 patients vs five [3%] of 171 patients), whereas the incidence was similar between treatment groups among patients with no previous docetaxel use (seven [3%] of 253 patients vs one [1%] of 130 patients). The incidences of grade 3-4 anaemia and neutropenia were similar between the radium-223 and placebo groups within both docetaxel subgroups. INTERPRETATION: Radium-223 is effective and well tolerated in patients with castration-resistant prostate cancer and symptomatic bone metastases, irrespective of previous docetaxel use. FUNDING: Algeta ASA and Bayer HealthCare Pharmaceuticals.

A phase IIa, nonrandomized study of radium-223 dichloride in advanced breast cancer patients with bone-dominant disease.

Radium-223 dichloride (radium-223) mimics calcium and emits high-energy, short-range alpha-particles resulting in an antitumor effect on bone metastases. This open-label, phase IIa nonrandomized study investigated safety and short-term efficacy of radium-223 in breast cancer patients with bone-dominant disease. Twenty-three advanced breast cancer patients with progressive bone-dominant disease, and no longer candidates for further endocrine therapy, were to receive radium-223 (50 kBq/kg IV) every 4 weeks for 4 cycles. The coprimary end points were change in urinary N-telopeptide of type 1 (uNTX-1) and serum bone alkaline phosphatase (bALP) after 16 weeks of treatment. Exploratory end points included sequential (18)F-fluorodeoxyglucose positron emission tomography and computed tomography (FDG PET/CT) to assess metabolic changes in osteoblastic bone metastases. Safety data were collected for all patients. Radium-223 significantly reduced uNTX-1 and bALP from baseline to end of treatment. Median uNTX-1 change was -10.1 nmol bone collagen equivalents/mmol creatinine (-32.8 %; P = 0.0124); median bALP change was -16.7 ng/mL (-42.0 %; P = 0.0045). Twenty of twenty-three patients had FDG PET/CT identifying 155 hypermetabolic osteoblastic bone lesions at baseline: 50 lesions showed metabolic decrease (≥25 % reduction of maximum standardized uptake value from baseline) after 2 radium-223 injections [32.3 % metabolic response rate (mRR) at week 9], persisting after the treatment period (41.5 % mRR at week 17). Radium-223 was safe and well tolerated. Radium-223 targets areas of increased bone metabolism and shows biological activity in advanced breast cancer patients with bone-dominant disease.

Phase I pharmacokinetic and biodistribution study with escalating doses of ²²³Ra-dichloride in men with castration-resistant metastatic prostate cancer.

PURPOSE: ²²³Ra-Dichloride (²²³Ra) is a novel bone-seeking alpha-emitter that prolongs survival in patients with castration-resistant metastatic prostate cancer. We conducted a study to better profile the pharmacokinetics, pharmacodynamics, and biodistribution of this agent. METHODS: Ten patients received either 50, 100, or 200 kBq of ²²³Ra per kilogram of body weight. Subsequently, six of these ten patients received a second dose of 50 kBq/kg. Pharmacokinetics and biodistribution were assessed by serial blood sampling, planar imaging, and whole-body counting. Pharmacodynamic assessment was based on measurements of prostate-specific antigen, bone alkaline phosphatase, and serum N-telopeptide. Safety was also assessed. RESULTS: Pharmacokinetic studies showed rapid clearance of ²²³Ra from the vasculature, with a median of 14% (range 9-34%), 2% (range 1.6-3.9%), and 0.5% (range 0.4-1.0%) remaining in plasma at the end of infusion, after 4 h, and after 24 h, respectively. Biodistribution studies showed early passage into the small bowel and subsequent fecal excretion with a median of 52% of administered ²²³Ra in the bowel at 24 h. Urinary excretion was relatively minor (median of 4% of administered ²²³Ra). Bone retention was prolonged. No dose-limiting toxicity was observed. Pharmacodynamic effects were observed (alkaline phosphatase and serum N-telopeptides) in a significant fraction of patients. CONCLUSION: ²²³Ra cleared rapidly from plasma and rapidly transited into small bowel, with fecal excretion the major route of elimination. Administered activities up to 200 kBq/kg were associated with few side effects and appeared to induce a decline in serum indicators of bone turnover.

Radiation safety considerations for the use of ²²³RaCl2 DE in men with castration-resistant prostate cancer.

The majority of patients with late stage castration-resistant prostate cancer (CRPC) develop bone metastases that often result in significant bone pain. Therapeutic palliation strategies can delay or prevent skeletal complications and may prolong survival. An alpha-particle based therapy, radium-223 dichloride (²²³RaCl2), has been developed that delivers highly localized effects in target areas and likely reduces toxicity to adjacent healthy tissue, particularly bone marrow. Radiation safety aspects were evaluated for a single comprehensive cancer center clinical phase 1, open-label, single ascending-dose study for three cohorts at 50, 100, or 200 kBq kg⁻¹ body weight. Ten patients received administrations, and six patients completed the study with 1 y follow-up. Dose rates from patients administered ²²³Ra dichloride were typically less than 2 µSv h⁻¹ MBq⁻¹ on contact and averaged 0.02 µSv h⁻¹ MBq⁻¹ at 1 m immediately following administration. Removal was primarily by fecal excretion, and whole body effective half-lives were highly dependent upon fecal compartment transfer, ranging from 2.5-11.4 d. Radium-223 is safe and straightforward to administer using conventional nuclear medicine equipment. For this clinical study, few radiation protection limitations were recommended post-therapy based on facility evaluations. Specific precautions are dependent on local regulatory authority guidance. Subsequent studies have demonstrated significantly improved overall survival and very low toxicity, suggesting that ²²³Ra may provide a new standard of care for patients with CRPC and bone metastases.

Quantitative imaging of 223Ra-chloride (Alpharadin) for targeted alpha-emitting radionuclide therapy of bone metastases.

OBJECTIVE: Ra is an alpha particle emitter that targets areas of increased bone turnover in bone metastases. Alpha particles account for 95% of the 27.8 MeV emitted per decay. Less than 2% of the emissions are from photons. This means that a high absorbed dose will be delivered locally, although the number of photons for imaging will be low. The purpose of this study was to investigate the possibility of quantitative imaging of Ra to enable biodistribution studies. METHODS: A Philips Forte gamma camera, equipped with a medium-energy collimator, was used. Basic imaging parameters were determined from phantom studies, and the accuracy of activity quantification was tested in a phantom study and within a patient study. RESULTS: Imaging parameters were determined for the three most suitable photon peaks from the acquired energy spectrum (82, 154 and 270 keV). Camera sensitivity is constant for circular sources with areas greater than 10 cm. The spatial resolution (full-width at half-maximum) was 1.1 cm for each of the three energy windows. The possibility for quantitative imaging was further investigated for the 82 keV energy window, which showed the highest sensitivity and spatial resolution. A phantom study showed that activity could be quantified to within 10% for a 200 ml volume placed within water containing background activity and to within 50% for a 0.5 ml phantom. Quantification of activity in bone after administrations of 100 kBq/kg of Ra-chloride proved the feasibility of quantitative imaging of patients who have received radionuclide therapy. CONCLUSION: Because of the high-energy deposition of Ra, only a low injected activity is required for therapy, which results in a low count rate for the gamma camera. Nevertheless, this study has demonstrated that it is possible to quantify uptake with a sufficient degree of accuracy to obtain clinically relevant information.

A bone marrow toxicity model for ²²³Ra alpha-emitter radiopharmaceutical therapy.

Ra-223, an α-particle emitting bone-seeking radionuclide, has recently been used in clinical trials for osseous metastases of prostate cancer. We investigated the relationship between absorbed fraction-based red marrow dosimetry and cell level-dosimetry using a model that accounts for the expected localization of this agent relative to marrow cavity architecture. We show that cell level-based dosimetry is essential to understanding potential marrow toxicity. The GEANT4 software package was used to create simple spheres representing marrow cavities. Ra-223 was positioned on the trabecular bone surface or in the endosteal layer and simulated for decay, along with the descendants. The interior of the sphere was divided into cell-size voxels and the energy was collected in each voxel and interpreted as dose cell histograms. The average absorbed dose values and absorbed fractions were also calculated in order to compare those results with previously published values. The absorbed dose was predominantly deposited near the trabecular surface. The dose cell histogram results were used to plot the percentage of cells that received a potentially toxic absorbed dose (2 or 4 Gy) as a function of the average absorbed dose over the marrow cavity. The results show (1) a heterogeneous distribution of cellular absorbed dose, strongly dependent on the position of the cell within the marrow cavity; and (2) that increasing the average marrow cavity absorbed dose, or equivalently, increasing the administered activity resulted in only a small increase in potential marrow toxicity (i.e. the number of cells receiving more than 4 or 2 Gy), for a range of average marrow cavity absorbed doses from 1 to 20 Gy. The results from the trabecular model differ markedly from a standard absorbed fraction method while presenting comparable average dose values. These suggest that increasing the amount of radioactivity may not substantially increase the risk of toxicity, a result unavailable to the absorbed fraction method of dose calculation.

18F-fluoride PET: changes in uptake as a method to assess response in bone metastases from castrate-resistant prostate cancer patients treated with 223Ra-chloride (Alpharadin).

BACKGROUND: A qualitative assessment of conventional bone scintigraphy with 99mTc methylene diphosphonate is perceived as an insensitive method for monitoring the treatment response of bone metastases, and we postulated that semi-quantitative 18F-fluoride positron emission tomography (PET) might serve as a suitable alternative biomarker of the treatment response. METHODS: Five patients with castrate-resistant prostate cancer and bone metastases with no known soft tissue disease received 100 kBq/kg of radium-223 (223Ra)-chloride (Alpharadin) therapy at 0 and 6 weeks and had whole body 18F-fluoride PET scans at baseline, 6 and 12 weeks with concurrent prostatic-specific antigen (PSA) and alkaline phosphatase (ALP) measurements. A qualitative comparison of the PET scans was performed blinded to the PSA and ALP results. A semi-quantitative comparison was made by measuring the maximum standardised uptake values (SUVmax) in five bone metastases in each patient. The means of the five SUVmax measurements in each subject were used as a quantitative measure of global metastatic activity at each time point. RESULTS: Three patients showed a PSA decline at 12 weeks (-44%, -31%, -27% reduction) whilst two patients showed PSA increases (+10%, +17%). All five patients showed a reduction in ALP of greater than 25%. The qualitative assessment of the 18F-fluoride scans recorded a stable disease in each case. However, the semi-quantitative assessment showed agreement with the PSA decline in three patients (-52%, -75%, -49%) and minimal change (+12%, -16%) in two patients with increased PSA at 12 weeks. Four patients showed similar reductions in mean SUVmax and ALP at 12 weeks. CONCLUSIONS: The semi-quantitative 18F-fluoride PET is more accurate than the qualitative comparison of scans in assessing response in bone metastases, correlating with the PSA response and ALP activity and offering a potential imaging biomarker for monitoring treatment response in bone metastases following treatment with 223Ra-chloride.