No abstract

Radium-223 is a targeted alpha radiation therapy for metastatic castration-resistant prostate cancer. DNA damage repair (DDR) defective prostate cancers, specifically genetic aberrations leading to homologous recombination deficiency (HRD), accumulate irreparable DNA damage following genotoxic treatment. This retrospective study assessed DDR mutation status in patients treated with radium-223, investigating their association with efficacy and overall survival (OS). Patients and methods: Included patients were treated with radium-223 and had results from primary or metastatic tumour tissue of a comprehensive next-generation sequencing panel of DDR genes, including canonical HRD genes. Patients were grouped by presence (DDRþ) or absence (DDRÀ) of pathogenic somatic or germline aberrations in DDR genes. We evaluated OS, time to ALP progression (TAP), time to initiation of subsequent systemic therapy (TST) and biochemical responses between DDR groups.

Platinum-based chemotherapy is not standard of care for unselected or genetically selected metastatic castration-resistant prostate cancer (mCRPC) patients. A retrospective assessment of 71 patients was performed on platinum use in the Netherlands. Genetically unselected patients yielded low response rates. For a predefined subanalysis of all patients with comprehensive next-generation sequencing, 30 patients were grouped based on the presence of pathogenic aberrations in genes associated with DNA damage repair (DDR) or aggressive variant prostate cancer (AVPC). Fourteen patients (47%) were DDR deficient (DDRd), of which seven with inactivated BRCA2 (BRCA2mut). Six patients classified as AVPC. DDRd patients showed beneficial biochemical response to carboplatin, largely driven by all BRCA2mut patients having >50% prostate-specific antigen (PSA) decline and objective radiographic response. In the wild-type BRCA2 subgroup, 35% had a >50% PSA decline (P = .006) and 16% radiographic response (P < .001). Median overall survival was 21 months for BRCA2mut patients vs 7 months (P = .041) for those with functional BRCA2. AVPC patients demonstrated comparable responses to non-AVPC, including a similar overall survival, despite the poor prognosis for this subgroup. In the scope of the registration of poly-(ADP)-ribose polymerase inhibitors (PARPi) for mCRPC, we provide initial insights on cross-resistance between PARPi and platinum compounds. By combining the literature and our study, we identified 18 patients who received both agents. In this cohort, only BRCA2mut patients treated with

Aim: Timing of radium-223 (Ra-223) in metastatic castration-resistant prostate cancer (mCRPC) remains challenging due to alternative options and short window of opportunity. Methods: Ra-223 treated patients in the CAPRI-registry were included. Outcomes were evaluated based on treatment line of Ra-223. Results: Out of 285 patients, 49% received Ra-223 in line ≥3. 51% completed six Ra-223 injections and 34% had a symptomatic skeletal event after first Ra-223 without differences between subgroups. After correction of known prognostic factors Ra-223 in line ≥3 (HR: 3.267; 95% CI: 1.689–6.317; p < 0.01) remained associated with worse OS. Conclusion: In the Netherlands, Ra-223 was mainly started as second or third mCRPC-treatment in 2014–2018. Later timing of Ra-223 did affect OS, but not treatment completion and occurrence of symptomatic skeletal events.

Purpose Radium-223 is a life-prolonging therapy for castration-resistant prostate cancer (CRPC) patients with symptomatic bone metastases. However, validated biomarkers for response monitoring are lacking. The study aim was to investigate whether early alkaline phosphatase (ALP) dynamics after the first radium-223 injection can act as surrogate marker for overall survival (OS). Methods This retrospective multicenter study included consecutive CRPC patients treated with radium-223. Patients were divided into four subgroups based on baseline ALP level (normal/elevated) and early ALP response, defined as ≥10% ALP decrease after the first radium-223 injection. Primary endpoint was OS among the subgroups. Secondary endpoints included time to first skeletal-related event, time to ALP progression, and treatment completion rate. Results A total of 180 patients were included for analysis. Median OS was 13.5 months (95% confidence interval 11.5–15.5). Patients with elevated baseline ALP without ALP response after the first injection had significantly worse OS when compared to all other patients (median OS 7.9 months versus 15.7 months, hazard ratio 2.56, 95% confidence interval 1.73–3.80, P < 0.001). Multivariate analysis demonstrated that elevated baseline ALP without ALP response after the first injection, the number of prior systemic therapies, baseline LDH level, and baseline ECOG performance status were prognostic factors of OS. Patients with elevated baseline ALP without ALP response after the first injection had significantly shorter times to ALP progression and first skeletal-related event, and more frequently discontinued radium-223 therapy when compared to other patients. Conclusion Early treatment–induced changes in ALP after one radium-223 injection were associated with OS in metastatic CRPC patients.