Predictors of long-term response to abiraterone in patients with metastastic castration-resistant prostate cancer: a retrospective cohort study

We aimed to identify clinical predictors of long-term response to abiraterone (defined as >12 months drug exposure) in a retrospective cohort of metastatic castration-resistant prostate cancer patients treated in post-docetaxel setting at 24 Italian centers. The Cox proportional hazards model was used to analyze the association between clinical features and the duration of drug exposure. Results were expressed as hazard ratios (HR) with associated 95% confidence intervals (CI). A total of 143 patients met the inclusion criteria. Their median age was 73 years, median Gleason score 8 and median abiraterone exposure 20 months. At the univariate analysis, a significant correlation with the duration of abiraterone exposure was found for Gleason score (HR 0.82, 95% CI 0.71-0.96; p=0.012), PSA (HR 1.10, 95% CI 1.03-1.18; p=0.08) and lactic dehydrogenase levels (HR 1.22, 95% CI 1.02-1.46; p=0.027), while the association between lower alkaline phosphatase levels and treatment duration was marginally significant (HR 1.07, 95% CI 0.99-1.16; p=0.074). Only PSA and Gleason score were predictive of long-term treatment duration in the multivariate analysis. No other clinical factors resulted to be predictive of sustained response to abiraterone, including metastatic disease at diagnosis and visceral disease, suggesting that all subgroups of patients may derive a substantial clinical benefit from abiraterone treatment. These findings need to be validated in prospective, larger studies

Cabozantinib in the elderly with metastatic renal cell carcinoma undergoing geriatric G8 screening test: A prospective multicenter observational study (ZEBRA/MEET-URO 9)

Background: Cabozantinib (CABO) is an oral tyrosine kinase inhibitor registered for the treatment of metastatic renal cell carcinoma (mRCC) for the first or subsequent lines. Tolerability in real world elderly patients is poorly documented. G8 is a short test for vulnerability gaining increased interest as a screening tool for trials in geriatric oncology. Methods: ZEBRA/MEET-URO 9 was a prospective multicenter study of safety and activity of CABO administered to pts ≥70 years with mRCC, either in the first or subsequent lines of treatment, until progression or unacceptable toxicity. All pts underwent G8 score at baseline, with a cut-off for vulnerability of 14 or below. Data on tolerability and activity were collected prospectively after signature of informed consent. Results: A total of 104 pts started CABO at 13 Italian Centers, 38,5% as first line. Median age was 75.8 yrs (range 70.2-87.4 yrs, 26 pts ≥80 yrs), 73.1% males. IMDC score was good 19.2%, intermediate 53.9%, poor 26.9%. Primary tumor had been removed in 82.7% of pts, histology was clear cell 78.8%, papillary 8.7%, chromophobe 5.8%, unclassified 6.7%. G8 score was ≤14 in 65.4% of pts. Up-front dose reduction of CABO was more frequent in pts with low G8 score (79.4 vs 41.7%, p=0.003), but eventually the majority of pts (91.4%) underwent dose reductions of CABO. After a median treatment of 6.4 months (0.5-26.1 months), 38.4% of pts developed G3-4 toxicities, 22.1% interrupted treatment due to adverse events, 2.8% (3 pts) died due to cardiovascular or thromboembolic events. Median PFS was 7.6 months (95% CI=5.8-12.6 months) in first line, 10.0 months (5.8-15.6) in second or further lines, median OS was 20.1 months (11.1-not reached) and 15.6 months (12.5-not reached), respectively. G8 score ≤14 did not correlate with rate of temporary interruptions >7 days, hospitalization, incidence of G3-5 toxicities, as well as with PFS. Pts with G8 score ≤14 had a trend for reduced OS, but difference was not statistically significant both in the first and further lines of treatment. Conclusions: Screening G8 test was positive in more than a half of pts, underlying the need for detailed geriatric assessment and increased clinical monitoring of such patients. A G8 score ≤14 correlated with up-front dose reduction of CABO but not with G3-5 toxicities probably due to the high rates of dose reductions in the whole cohort. Correlation between low G8 score and OS could not be demonstrated in this population

Effectiveness of abiraterone acetate plus prednisone in chemotherapy-naïve patients with metastatic castration-resistant prostate cancer in a large prospective real-world cohort: the ABItude study

Real-world data on chemotherapy-naïve patients with metastatic castration-resistant prostate cancer (mCRPC) treated with abiraterone plus prednisone are limited, largely deriving from small retrospective studies

Effects of abiraterone acetate plus prednisone on bone turnover markers in chemotherapy-naïve mCRPC patients after ADT failure: a prospective analysis of the italian real-world study ABITUDE

Background: Bone remodeling is disrupted in metastatic disease, which affects > 70% of metastatic castration-resistant prostate cancer (mCRPC) patients. As a result, abnormal levels of specific bone turnover biomarkers (BTMs) are released. In this prospective ancillary analysis of the Italian real-world study ABITUDE, four markers were measured during abiraterone acetate plus prednisone (AAP) treatment in chemotherapy-naïve mCRPC men failing androgen-deprivation therapy. Methods: Patients were enrolled if a blood sample was obtained before the first administration of abiraterone (baseline); ad-hoc blood samples were withdrawn during routine tests after 3, 6, and 12 months. A centralized lab measured bone alkaline phosphatase (BALP, osteoblast activity marker), type-I collagen-C-telopeptide (CTX-1, bone resorption marker), parathyroid hormone (PTH) and vitamin D (vitD). At each time point, intra-patient variations vs baseline were compared by the signed-rank test (statistical significance: P-value < 0.05). Results: Of 481 patients enrolled in ABITUDE, 186 (median age: 76 [range: 53-93] years) met the substudy criteria: 74.7% had bone metastases, 11.8% were on bone-targeted therapies (BTT) and 14.0% on vitD supplementation. BALP decreased significantly at month 6 (P = 0.0010) and 12 (P < 0.0001) and CTX-1 at month 6 (P = 0.0028); PTH increased at month 3 (P < 0.0001); no significant difference in vitD levels was observed. Similar findings were observed in BTT-untreated patients. The reduction in BALP and CTX-1 levels was more pronounced in patients with than without bone metastases; in the latter group, no significant variation in BALP and CTX-1 levels was observed. Conclusions: AAP seems to exert an effect on the microenvironment of metastatic but not of normal bone, which likely contributes to its antitumoral activity