Lutetium [Lu-177] vipivotide tetraxetan 7,400MBq/7.5-12.5ml solution for injection vials

BACKGROUND: Lutetium-177 PSMA radioligand therapy ([¹⁷⁷Lu]Lu-PSMA-RLT) is an effective treatment option for patients with metastatic castration-resistant prostate cancer (mCRPC). Prospective studies reported favourable efficacy and safety outcomes of up to 6 cycles of [¹⁷⁷Lu]Lu-PSMA. This study aimed to evaluate the efficacy and safety of [¹⁷⁷Lu]Lu-PSMA rechallenge therapy in patients with mCRPC who progressed after an initial course of [¹⁷⁷Lu]Lu-PSMA-RLT. METHODS: This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. A systematic search was performed using relevant keywords in PubMed, EMBASE, and Scopus from establishment to March 2025. Primary endpoints included biochemical responses with a decline in prostate-specific antigen (PSA) of more than 50% and any PSA decline. Secondary outcomes included survival outcomes and treatment-related toxicity following rechallenge therapy with [¹⁷⁷Lu]Lu-PSMA. A random-effects model was used to generate pooled proportions through meta-analysis. RESULTS: Eleven studies with 307 patients were included in the final analysis. Of these, 196 received 177Lu-PSMA RLT alone, and 111 received tandem 177Lu/225Ac-PSMA RLT. The pooled proportions of patients with more than a 50% PSA decline and any PSA decline were 0.45 (95% CI: 0.36–0.54) and 0.71 (95% CI: 0.61–0.80), respectively. In a total of 102 patients, 44 (43%) showed low-grade 1–2 xerostomia; however, no cases of serious xerostomia (grade ≥ 3) were reported. Moreover, the pooled proportion of patients experiencing grade ≥ 3 toxicity was 0.14 (95% CI: 0.09–0.19). CONCLUSION: Rechallenge therapy with [¹⁷⁷Lu]Lu-PSMA is a feasible and safe treatment option for late/end mCRPC patients. Tandem approaches with [225Ac]Ac-PSMA may help expand understanding of how to optimize outcomes after [¹⁷⁷Lu]Lu-PSMA progression. However, these findings require confirmation in prospective, randomized studies comparing different rechallenge strategies to define optimal sequencing and patient selection criteria in advanced prostate cancer.

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BackgroundDrug interactions with diagnostic radiopharmaceuticals are well recognized, as they can modify biodistribution and lead to false or misleading diagnostic results. However, little is known about such interactions in the field of therapeutic radiopharmaceuticals, despite their rapid expansion-particularly with targeted radionuclide therapies such as Radioligand Therapy (RLT). This review aims, for the first time, to systematically compile and analyze available data on drug interactions involving therapeutic radiopharmaceuticals, in order to support safer and more effective patient care.Main bodyEighty-three articles investigating drug interactions with [177Lu]Lu-oxodotreotide (Lutathera®), [177Lu]Lu-vipivotide tetraxetan (Pluvicto®), [131I]INa, [131I]I-meta-iodobenzylguanidine ([131I]I-MIBG), [223Ra]RaCl2 (Xofigo®), [90Y]Y-ibritumomab tiuxetan (Zevalin®) or [153Sm]Sm-lexidronam pentasodium (Quadramet®) were included. These studies reported 133 drug interactions, 69% of which were not mentioned in the corresponding summaries of product characteristics. Interactions could be beneficial (e.g., reducing renal toxicity) or harmful (e.g., decreasing therapeutic efficacy or potentiating toxicity). Three interactions involved complementary and alternative medicines (quercetin, Ginkgo biloba and ouabain). Overall, the evidence level for reported interactions was low: 88% were classified as level 3 or 4 according to the Centre for Evidence-Based Medicine (CEBM) scale.ConclusionDrug interactions with therapeutic radiopharmaceuticals remain underreported, yet they may have significant clinical consequences. Clinical radiopharmacy plays a key role in detecting and preventing these interactions. Radiopharmacists, through their expertise, can identify potential interactions, influence therapeutic decisions, and positively impact patient management. Their involvement throughout the care pathway is essential to ensure the safe and effective use of these innovative therapies. Nuclear medicine physicians should also be aware that such interactions can alter biodistribution, compromise therapeutic efficacy, and increase the risk of adverse effects.

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ImportanceObserved treatment effects on overall survival (OS) differed substantially in the first 2 randomized clinical trials of lutetium Lu 177 vipivotide tetraxetan (Lu-177) prostate-specific membrane antigen (PSMA) in metastatic castration-resistant prostate cancer.ObjectiveTo investigate factors associated with the observed difference in treatment effects on OS, including differences in the risk of crossover from randomized treatment after disease progression.Design, setting, and participantsThis comparative effectiveness study used individual participant data from 2 randomized clinical trials, TheraP (A Randomised Phase 2 Trial of 177Lu-PSMA617 Theranostic Versus Cabazitaxel in Progressive Metastatic Castration Resistant Prostate Cancer [ANZUP Protocol 1603]) (n = 200), recruited from February 2018 to September 2019 in Australia, and published data from VISION (An International, Prospective, Open Label, Multicenter, Randomized Phase 3 Study of 177Lu-PSMA-617 in the Treatment of Patients With Progressive PSMA-Positive Metastatic Castration-Resistant Prostate Cancer) (n = 831), recruited from June 2018 to October 2019 in North America and Europe. Individual participant data for OS were reconstructed from VISION using the published survival curves. Data were analyzed February 6, 2018, to December 31, 2021, for TheraP and June 4, 2018, to January 27, 2021, for VISION.InterventionsTheraP randomized participants to receive treatment with Lu-177 PSMA or cabazitaxel. VISION randomized participants to receive treatment with or without Lu-177 PSMA in addition to physicians' choice of protocol-permitted treatments (PPT; approved hormonal treatments [such as abiraterone and enzalutamide], bisphosphonates, radiotherapy, denosumab, or glucocorticoids), excluding cabazitaxel.Main outcomes and measuresPatient characteristics, treatment protocols, and OS outcomes of the 2 trials were compared. Estimates of the effect on OS from TheraP were adjusted for crossover from randomly assigned treatment using a rank-preserving structural failure time model (RPSFTM) and inverse probability of censoring weights (IPCW) methods.ResultsThe 200 participants in TheraP and 831 participants in VISION were similar in age (median [range], 72 [49-86] vs 71 [40-94] years). Improved OS was observed in the comparator treatment group (cabazitaxel) in TheraP compared with VISION (PPT) (hazard ratio [HR], 0.53 [95% CI, 0.39-0.71]). The Lu-177 PSMA treatment groups in TheraP and VISION had similar OS (HR, 0.92 [95% CI, 0.70-1.19]). In TheraP, 20 of 101 participants in the cabazitaxel group crossed over to Lu-177 PSMA, while 32 of 99 participants in the Lu-177 PSMA arm crossed over to cabazitaxel. No statistically significant differences in OS between the Lu-177 PSMA and cabazitaxel groups of TheraP were observed after controlling for crossover to cabazitaxel: RPSFTM HR, 0.97 (95% CI, 0.60-1.58); IPCW HR, 0.92 (95% CI, 0.65-1.32); RPSFTM HR, 0.97 (95% CI, 0.60-1.58) and IPCW HR, 0.82 (95% CI, 0.54-1.24) for crossover to Lu-177 PSMA; RPSFTM HR, 0.96 (95% CI, 0.53-1.74) and IPCW HR, 0.82 (95% CI, 0.53-1.27) for crossover to either Lu-177 PSMA or cabazitaxel.Conclusions and relevanceFindings of this secondary analysis of the TheraP and VISION randomized clinical trials suggest that the choice of comparator treatments (ie, cabazitaxel vs PPT) may explain the difference in the observed effect of Lu-177 PSMA on OS between the 2 trials. Causal inference methods such as RPSFTM and IPCW may help rule out crossover as a plausible explanation.

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Prostate-specific membrane antigen (PSMA) is highly expressed in prostate cancer and a therapeutic target. Lutetium-177 (177Lu)-PSMA-617 is the first radioligand therapy to be approved in Canada for use in patients with metastatic castration-resistant prostate cancer (mCRPC). As this treatment represents a new therapeutic class, guidance regarding how to integrate it into clinical practice is needed. This article aims to review the evidence from prospective phase 2 and 3 clinical trials and meta-analyses of observational studies on the use of 177Lu-PSMA-617 in prostate cancer and discuss how Canadian clinicians might best apply these data in practice. The selection of appropriate patients, the practicalities of treatment administration, including necessary facilities for treatment procedures, the assessment of treatment response, and the management of adverse events are considered. Survival benefits were observed in clinical trials of 177Lu-PSMA-617 in patients with progressive, PSMA-positive mCRPC who were pretreated with androgen receptor pathway inhibitors and taxanes, as well as in taxane-naïve patients. However, the results of ongoing trials are awaited to clarify questions regarding the optimal sequencing of 177Lu-PSMA-617 with other therapies, as well as the implications of predictive biomarkers, personalized dosimetry, and combinations with other therapies.

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Disseminated intravascular coagulation (DIC) is a hematological disorder characterized by the abnormal activation of the coagulation system, which leads to widespread clotting and subsequent consumption coagulopathy. DIC is often associated with the progression of prostate cancer and can be a life-threatening condition. In this case report, we present a patient with recurrent DIC in the setting of advanced prostate cancer. His initial episode of DIC was effectively managed with a triple therapy regimen of leuprolide, docetaxel, and darolutamide. However, during a subsequent episode of DIC, which occurred with progression to widespread bone metastases, a single dose of Lu-177 vipivotide tetraxetan successfully resolved the condition. Circulating tumor DNA testing at the onset of the second episode of DIC revealed high levels of androgen receptor, CCND1, and PDGFRA gene amplification. This case not only underscores the critical importance of awareness, early diagnosis, and the prompt initiation of effective cancer therapy for managing life-threatening DIC associated with prostate cancer but also offers new molecular insights into the condition.

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Radiopharmaceuticals have been utilized for men with advanced prostate cancer for decades. Older agents, seldom used today, provided palliation for bone metastatic pain. In 2013, the alpha emitter radium-223 provided a catalyst for the field by prolonging survival in men with metastatic castrate-resistant prostate cancer (mCRPC). Recently radioisotopic therapies have gained further interest with the development and FDA approval of 177 lutetium (177Lu)-PSMA-617 (also known as lutetium Lu-177 vipivotide tetraxetan). This agent targets the prostate-specific membrane antigen (PSMA) expressed on the cell surface of prostate cancer cells with a beta-emitting isotope (177Lu). This clinical review summarizes key data reported from 177Lu-PSMA-617 clinical trials, including data from the phase III VISION trial which were pivotal for regulatory approval in heavily pretreated PSMA-PET-positive patients with mCRPC. The current field of radiopharmaceuticals is in a rapid state of flux. Additional phase III trials are now ongoing in patients with mCRPC and in patients with metastatic castrate-sensitive prostate cancer. The results from these potential practice-changing trials are highly anticipated. Earlier phase trials (I/II) are in progress examining combination therapies, radiolabeled monoclonal antibodies, and novel compounds. Studies of PSMA-targeted therapies using both beta emitters such as 177Lu and novel alpha emitters such 225 actinium are in progress. During the next decade, radiopharmaceuticals will likely play a central role in the management of patients with advanced prostate cancer.

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Opinion statementThe management of metastatic castrate-resistant prostate cancer (mCRPC) has evolved in the past decade due to substantial advances in understanding the genomic landscape and biology underpinning this form of prostate cancer. The implementation of various therapeutic agents has improved overall survival but despite the promising advances in therapeutic options, mCRPC remains incurable. The focus of treatment should be not only to improve survival but also to preserve the patient's quality of life (QoL) and ameliorate cancer-related symptoms such as pain. The choice and sequence of therapy for mCRPC patients are complex and influenced by various factors, such as side effects, disease burden, treatment history, comorbidities, patient preference and, more recently, the presence of actionable genomic alterations or biomarkers. Docetaxel is the first-line treatment for chemo-naïve patients with good performance status and those who have yet to progress on docetaxel in the castration-sensitive setting. Novel androgen agents (NHAs), such as abiraterone and enzalutamide, are effective treatment options that are utilized as second-line options. These medications can be considered upfront in frail patients or patients who are NHA naïve. Current guidelines recommend genetic testing in mCRPC for mutations in DNA repair deficiency genes to inform treatment decisions, as for example in breast cancer gene mutation testing. Other potential biomarkers being investigated include phosphatase and tensin homologues and homologous recombination repair genes. Despite a growing number of studies incorporating biomarkers in their trial designs, to date, only olaparib in the PROFOUND study and lutetium-177 in the VISION trial have improved survival. This is an unmet need, and future trials should focus on biomarker-guided treatment strategies. The advent of novel noncytotoxic agents has enhanced targeted drug delivery and improved treatment responses with favourable toxicity profiling. Trials should continue to incorporate and report health-related QoL scores and functional assessments into their trial designs.

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