Efficacy of Metronomic Oral Vinorelbine, Cyclophosphamide, and Capecitabine vs Weekly Intravenous Paclitaxel in Patients With Estrogen Receptor-Positive, ERBB2-Negative Metastatic Breast Cancer: Final Results From the Phase 2 METEORA-II Randomized Clinical Trial

Importance

In spite of the effectiveness of endocrine therapy plus cyclin-dependent kinase (CDK) 4/6 inhibitors as the first-line treatment for estrogen receptor (ER)-positive, erb-b2 receptor tyrosine kinase 2 (ERBB2 [formerly HER2/neu])-negative (ER+/ERBB2-) metastatic breast cancer (MBC), patients eventually develop resistance, and eventually most will receive chemotherapy. The METEORA-II trial compared a metronomic all-oral treatment with intravenous (IV) chemotherapy.

Objective

To compare the efficacy of the oral vinorelbine plus cyclophosphamide plus capecitabine (VEX) regimen vs weekly IV paclitaxel among patients with ER+/ERBB2- MBC who are candidates for chemotherapy.

Design, Setting, and Participants

This phase 2 randomized clinical trial including 140 women 18 years and older (randomized 1:1) with ER+/ERBB2- MBC was carried out from September 13, 2017, to January 14, 2021 at 15 centers in Italy. Eligible patients could have received 1 prior line of chemotherapy for MBC and/or 2 lines of endocrine therapy (including CDK4/6 inhibitors).

Interventions

In 4-week cycles, patients received either metronomic oral VEX or weekly IV paclitaxel.

Main Outcomes and Measures

The primary end point was investigator-assessed time to treatment failure (TTF) defined as the interval between the date of randomization to the end of treatment (because of disease progression or lack of tolerability or because further trial treatment was declined). Secondary end points included progression-free survival (PFS), overall survival (OS), and disease control rate (complete or partial response or stable disease lasting for at least 24 weeks).

Results

In total, 133 patients received either VEX (n = 70) or paclitaxel (n = 63) in 4-weekly cycles. The median age was 61 (range, 30-80) years. The VEX treatment significantly prolonged TTF vs paclitaxel (hazard ratio [HR], 0.61; 95% CI, 0.42-0.88; P = .008), median TTF was 8.3 (95% CI, 5.6-11.1) months for VEX vs 5.7 (95% CI, 4.1-6.1) months for paclitaxel, and the 12-month TTF was 34.3% for VEX vs 8.6% for paclitaxel. The median PFS was 11.1 (95% CI, 8.3-13.8) months vs 6.9 (95% CI, 5.4-10.1) months favoring VEX (HR, 0.67; 95% CI, 0.46-0.96, P = .03). The 12-month PFS was 43.5% for VEX vs 21.9% for paclitaxel. No difference in OS was found. The TF event for 55.6% of patients was progression of disease; for 23% it was AEs. More patients assigned to VEX had at least 1 grade 3 or 4 targeted adverse event (VEX, 42.9%; 95% CI, 31.1%-55.3% vs paclitaxel, 28.6%; 95% CI, 17.9%-41.3%), but essentially no alopecia.

Conclusion and Relevance

This randomized clinical trial found significantly prolonged TTF and PFS for oral VEX but no improvement in OS compared with intravenous paclitaxel, despite increased but still manageable toxic effects. The VEX regimen may provide more prolonged disease control than weekly paclitaxel for ER+/ERBB2- MBC.

Trial Registration

ClinicalTrials.gov Identifier: NCT02954055.

First prospective data on breast cancer patients from the multicentre italian bone metastasis database

Bone metastases (BM) are still the main cause of morbidity in cancer patients because of skeletal-related events (SREs) that reduce quality of life. They have also led to increased social and healthcare costs. At present, data available on BM are insufficient. This was a multicentre prospective observational study of patients with BM from breast cancer (BC) with at least 6 months' follow-up. Information on patients at the first diagnosis of BM, including demographics and characteristics of the primary tumor and BM. Data were periodically updated by participating centres and reviewed by the coordinator centre. From October 2014 to July 2019, 618 patients with BM from solid tumors were enrolled and 220 were eligible for the present study. Median age was 62 years (range 26-86). Median follow-up was 34 months (range 6-149). At the time of enrolment, 109 (50%) had only BM (BOM) and 109 (50%) had concomitant visceral lesions and BM (BVM). Median time-to-first BM was 47 months (range 0-312) in BOM and 78.6 months in BVM patients. Disease-free interval differed on the basis of BC molecular subtype and stage. Ninety-eight BM patients had at least on SRE. Zoledronate was used in 69.1% of cases and denosumab in 28.3%. First-line treatment was hormone-based (50.7%), chemotherapy-based (38.7%) or chemotherapy- + hormone therapy-based (9.7%). Median progression-free and overall survival were 15.1 months (95% CI 12.6-18.4) and 66.8 months (95% CI 52.1-79.2), respectively. Our prospective study could substantially help to better understand the natural history of BM from BC.

Multicenter Italian bone metastasis database: First prospective data on breast cancer patients

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Background: Bone Metastases (BM) are still the main cause of morbidity and morbility in cancer patients because of their complications defined as skeletal-related events (SREs).SREs reduce pts quality of life and are associated with an increasing in social and health costs. At present, data concerning BM are mainly obtained retrospectively from monocentric experiences. Methods: We performed a multicentre prospective observational study of patients with BM from breast cancer (BC) with at least 6 month (m)'s follow-up who were registered in a prospective BM database (BMDB). Detailed information on patients at first diagnosis of BM was recorded in a custom-built software system, updated every 6 m by participating centres and reviewed by the coordinator centre.All pts have signed an informed consent. Results: Since October 2014,618 pts with BM from solid tumors were enrolled of whom 220 have BC as primitive site with a 6 m follow-up. Median age was 62 y (range 26-86). Median Follow up was 34 m (6-149). At enrolment 109 (50%) had only BM and 109 (50%) pts had concomitant visceral and BM. Median time to first BM was 47 m (range 0-312) in Bone only disease and 78.6 m in pts with visceral bone metastases. Disease Free interval (DFI) was different according to BC molecular subtypes and stage. The univariate hazard ratio (HR) for visceral or bone metastasis was higher in luminal B tumors (1.56, 95% confidence interval [CI]:1.1-2.3) (p = 0.002), basal-like (2.50, 95% CI:1.1-6.0) (p = 0.043), and HER2-enriched tumors (1.37, 95% CI:0.78-2.4) (p = 0.273). DFI for pts with stage I disease at diagnosis of primary BC was longer than that for stage III pts (median 67.2 m, 95%CI:53.1-96.1, vs. 58.1 m, 95%CI:41.9-73.4), with a HR of 1.84 (95% CI:1.1-3.0) (p = 0.015) for the stage III group, and 0.98 (95% C.I.:0.6-1.5) (p = 0.930) for the stage II group. During BM disease, 98 pts had at least 1 SREs . Zoledronate was used in 69.1% and Denosumab in 28.3% of cases. First line treatment was hormone-based (n = 105, 50.7%) chemo-based therapy (n = 80, 38.7%) and chemo+ormono based (n = 20, 9.7%). During follow up progression disease occurred in 167 pts. Median progression-free (mPFS) and overall survival calculated from metastatic disease diagnosis (mOS) were 15.1 m (95%CI 12.6-18.4) and 66.8 m (95%CI 52.1-79.2),respectively. Conclusions: This study presents prospective data about a cohort of BC pts enrolled at the first BM occurrence and followed over the time, extrapolated by the multicentric observational BMDB in order to better understed the clinical history of breast cancer and bone metastases.

Phase II Study of Dehydroepiandrosterone in Androgen Receptor-Positive Metastatic Breast Cancer

LESSONS LEARNED

The androgen receptor (AR) is present in most breast cancers (BC), but its exploitation as a therapeutic target has been limited.This study explored the activity of dehydroepiandrosterone (DHEA), a precursor being transformed into androgens within BC cells, in combination with an aromatase inhibitor (to block DHEA conversion into estrogens), in a two-stage phase II study in patients with AR-positive/estrogen receptor-positive/human epidermal growth receptor 2-negative metastatic BC.Although well tolerated, only 1 of 12 patients obtained a prolonged clinical benefit, and the study was closed after its first stage for poor activity.

BACKGROUND

Androgen receptors (AR) are expressed in most breast cancers, and AR-agonists have some activity in these neoplasms. We investigated the safety and activity of the androgen precursor dehydroepiandrosterone (DHEA) in combination with an aromatase inhibitor (AI) in patients with AR-positive metastatic breast cancer (MBC).

METHODS

A two-stage phase II study was conducted in two patient cohorts, one with estrogen receptor (ER)-positive (resistant to AIs) and the other with triple-negative MBC. DHEA 100 mg/day was administered orally. The combination with an AI aimed to prevent the conversion of DHEA into estrogens. The main endpoint was the clinical benefit rate. The triple-negative cohort was closed early.

RESULTS

Twelve patients with ER-positive MBC were enrolled. DHEA-related adverse events, reported in four patients, included grade 2 fatigue, erythema, and transaminitis, and grade 1 drowsiness and musculoskeletal pain. Clinical benefit was observed in one patient with ER-positive disease whose tumor had AR gene amplification. There was wide inter- and intra-patient variation in serum levels of DHEA and its metabolites.

CONCLUSION

DHEA showed excellent safety but poor activity in MBC. Although dose and patient selection could be improved, high serum level variability may hamper further DHEA development in this setting.

Enzalutamide after chemotherapy in advanced castration-resistant prostate cancer: the Italian Named Patient Program

AIM

To collect efficacy and safety data of enzalutamide after docetaxel, we retrospectively evaluated the Italian Named Patient Program results.

PATIENTS & METHODS

Two hundred and nine metastatic castration-resistant prostate cancer patients were enrolled. Median age was 73 years. Total 42.1% patients had pain, 14.4% had a performance status of two and 59.8% had a Gleason score ≥8. Total 31.1% had previously received ≥2 chemotherapies, 15.3 and 12% had been previously treated with abiraterone and cabazitaxel, respectively and 14.8% had received both.

RESULTS

 Median progression-free survival and overall survival were 4.8 and 13.1 months, respectively. A prostate-specific antigen reduction ≥50% was observed in 49.1%. Total 32.7% abiraterone-pretreated patients achieved a biochemical response compared with 56% of abiraterone-naive patients.

CONCLUSION

 Enzalutamide was safe and well tolerated. Its antitumor activity in abiraterone-pretreated patients was limited.

Long-term clinical impact of PSA surge in castration-resistant prostate cancer patients treated with abiraterone

BACKGROUND

Early changes in PSA have been evaluated in association to treatment outcome. The aim of this study was to assess PSA surge phenomenon in castration-resistant prostate cancer (CRPC) patients treated with abiraterone and to correlate those variations with long-term treatment outcome.

PATIENTS AND METHODS

We retrospectively evaluated 330 CRPC patients in 11 Italian hospitals, monitoring PSA levels at baseline and every 4 weeks. Other clinical, biochemical and molecular parameters were determined at baseline. We considered PSA surge as PSA increase within the first 8 weeks from starting abiraterone more than 1% from baseline followed by a PSA decline. The log-rank test was applied to compare survival between groups of patients according to PSA surge. The impact of PSA surge on survival was evaluated by Cox regression analyses.

RESULTS

A total of 330 patients with CRPC, median age 74 years (range, 45-90), received abiraterone (281 chemotherapy-treated and 49 chemotherapy-naïve). PSA surge was observed in 20 (7%) post-chemotherapy and 2 (4%) chemotherapy-naïve patients. For overall patients presenting PSA surge, timing of PSA peak from baseline was 5 ± 1.8 weeks and PSA rise from baseline was 21 ± 18.4%. The overall median follow-up was 23 months (range 1-62). No significant differences in progression-free survival and overall survival were observed between patients with and without PSA surge (P = 0.16 and =0.86, respectively). In addition, uni- and multivariate analyses showed no baseline factors related to PSA surge.

CONCLUSION

PSA surge occurs in both chemotherapy-treated and chemotherapy-naïve patients treated with abiraterone resulting, however, in no long-term impact on outcome. Physicians and patients should be aware of PSA surge challenge to prevent a premature discontinuation of potentially effective therapy with abiraterone. Further larger and prospective studies are warranted to investigate this not infrequent phenomenon.

Prognostic value of neutrophil-to-lymphocyte ratio (NLR) in metastatic castration-resistant prostate cancer (mCRPC) pts receiving a new agent (NA)- based third line treatment: Final results from a multicenter Italian study

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Background: High NLR has been reported to be a poor prognostic indicator in both first and second mCRPC lines, while no information is available concerning this issue in pts treated in third line therapy. The present study is aimed to assess the possible relationship between third line clinical outcomes and NLR in a series of mCRPC pts treated with a NA [abiraterone acetate (AA), cabazitaxel (CABA), or enzalutamide (ENZ)] after the failure of docetaxel (DOC) and another NA. Methods: We collected data of pts who received sequentially two NAs after DOC in 38 Italian hospitals. For each pt we recorded the clinical outcome of all treatments received after DOC. Cox regression analysis was used to assess the independent prognostic value of a series of pretreatment covariates, in terms of overall survival (OS), comprising NLR. Results: A consecutive series of 476 mCRPC pts with bone (86%), nodal (56%) or visceral (15%) mets, was collected. All pts received a NA-based third line: 135 received AA, 221 CABA and 120 ENZ. Data on NLR were available for 398 pts (84%). In the univariate analyses, the NLR as a discrete variable dichotomized according to the Maximally Selected Log-Rank statistics (optimal cut-off: 3.66), was significantly associated with both OS and progression free survival (PFS), calculated from the third line start (p < 0.0001). At the multivariate analysis, NLR, performance status, pain, hemoglobin, alkaline phosphatase, treatment with AA and with CABA were independent prognostic factors for PFS, while NLR, performance status, hemoglobin, PSA, and lactate dehydrogenase were independent prognostic factors for OS. In Kaplan-Meier analysis, the median OS from the start of third-line was higher (14.2 vs 9.3 mos) in pts with NLR ≤ 3.1 compared to those with NLR > 3.1 (log-rank; P < 0.0001). Similarly, the median PFS was 5.5 and 3.8 (log-rank; P < 0.0001) in pts with NLR ≤ 3.66 and > 3.66, respectively. Conclusions: Our results, observed in the largest cohort of mCRCP pts treated with NA-based third line after DOC and another NA, confirms that NLR is an independent factor for PFS and OS also in this population.

Patients with metastatic castration-resistant prostate cancer (mCRPC) are primary resistant (PR) to the new agent (NA)-based second line: Clinical outcomes and prognostic factors of subsequent treatment with another NA

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Background: Several NA [abiraterone acetate (AA), cabazitaxel (CABA), or enzalutamide (ENZ)] changed the prognosis of mCRPC pts being able to significantly prolong their overall survival (OS) after docetaxel failure. Unfortunately, a quote of pts experiences an early progression (within 3 mos) during the second line treatment and it is unclear if a clinical benefit may result from a subsequent treatment with another NA. The present study is aimed to assess the clinical outcomes and prognostic factors of subsequent NA treatment in those pts PR to the second line NA. Methods: We collected data of pts who received sequentially two NAs after DOC in 38 Italian hospitals. For each pt we recorded the clinical outcome of all treatments received after DOC. For the purpose of the present analysis we consider as PR pts who progressed within 3 months from the start of the NA second line. Cox regression analysis was used to assess the independent prognostic value of a series of third-line baseline covariates, in terms of progression free survival (PFS) and OS. Results: A consecutive series of 476 mCRPC pts with bone (86%), nodal (56%) or visceral (15%) mets, was collected. The NA-based second line consisted of AA (261 pts), CABA (151), and ENZ (64): we identified 55 PR pts (AA 24 – CABA 24 – ENZ 7). All pts received a subsequent NA-based third line: 22 received AA, 25 CABA, and 8 ENZ. Compared to no-PR pts, PR pts showed a lower biochemical response rate (12.2% vs 31.6%; p = 0.005), but no significant differences in terms of objective response rate (17.1% vs 15.2%), PFS (median 3.5 vs 4.7 mos), and OS (median 9.4 vs 12.9 mos). Considering the PR population, at the multivariate analysis , lactate dehydrogenase and PSA were independent prognostic factors for PFS in third line, while hemoglobin, PSA, administration of one NA in fourth line and lactate dehydrogenase were independent prognostic factors for OS. Conclusions: In our experience, NA-based third line is active also in mCRPC PR population and some factors may help in selecting patients with higher probability of achieving a disease control.

Activity of new agents (NAs) as third-line treatment in metastatic castration-resistant prostate cancer (mCRPC) patients (pts) after a long-term disease control (LTDC) with abiraterone acetate (AA) or enzalutamide (ENZ) post docetaxel (DOC): Preliminary results from a multicenter Italian study

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Background: Although the expected median progression free survival (mPFS) with AA and ENZ in DOC-pretreated pts is 6-8 mos, a quote of pts may experience a LTDC without progression of disease (PD) for more than 12 mos. Since the androgen receptor machinery remains the ultimate target of NAs in mCRPC post-DOC, some mechanisms of resistance could be common to all NAs. This may be crucial in planning their sequential use, mainly when a LTDC is observed in hormone NAs-based (HNAs) second line. The present study was aimed to assess the activity of NAs in pts who previously showed a LTDC with HNAs administered after DOC. Methods: We collected data of pts who received sequentially two NAs after DOC in 38 Italian hospitals. For each pt we recorded the clinical outcome of all treatments received after DOC. For the study purpose, LTDC was defined as the absence of PD ≥ 12 mos in pts treated with second-line AA or ENZ. Results: A consecutive series of 291 mCRPC pts, median age 71 yrs (46-91), with bone (88%), nodal (53%) or visceral (18%) mets, was collected. All pts received NAs as second line after DOC: in particular 160 (55%) received AA and 32 (11%) ENZ, with 41 pts (21%) showing a LTDC (36 AA – 5 ENZ). Among LTDC pts, third line treatment was cabazitaxel (CABA) in 25 cases and one hormonal NA in the remaining (2 AA - 14 ENZ). The clinical outcomes of the third line therapy are detailed in the table. Conclusions: From this preliminary data, it appears that third line CABA could be slightly more active in pts achieving a LTDC with HNAs in second line LTDC, despite the clinical outcomes were not significantly different compared to HNAs. Analyses on larger patients populations are needed to confirm these findings. [Table: see text]

Impact of visceral metastases on outcome to abiraterone after docetaxel in castration-resistant prostate cancer patients

BACKGROUND

The objective of this study was to analyze the impact of visceral metastases in castration-resistant prostate cancer (CRPC) treated with abiraterone.

MATERIALS & METHODS

All CRPC patients received abiraterone 1000 mg daily plus prednisone 10 mg orally daily. Liver and lung metastases were considered as visceral metastases.

RESULTS

Of 265 CRPC patients, 49 had visceral metastases. Results on progression-free survival were not significantly different in patients with or without visceral metastases. Conversely, the median overall survival between the two groups was 12.4 and 18.5 months (p = 0.01), respectively, and median overall survival of patients with liver-only disease versus other sites was 10.5 versus 18.5 months (p = 0.006), respectively.

CONCLUSION

Visceral disease appears to be an important predictor of clinical outcome in CRPC patients treated with abiraterone.

Primary resistance to abiraterone acetate (AA) after docetaxel treatment in metastatic castration-resistant prostate cancer (mCRPC): A multicenter retrospective analysis

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Background: AA improves survival in mCRPC patients pre-treated with docetaxel. All patients eventually become resistant at different interval times, but some of them show an early progression and should be considered as primary resistant (PRES). To date, no factors have been identified as predictive of primary resistance. Methods: The clinical outcomes of a consecutive series of patients treated with AA after docetaxel failure in 19 Italian Hospitals within a Named Patient Program (NPP) was previously reported (BJU 2014). In the present analysis, we focus on patients who achieved an investigator-assessed PFS ≤ 3 months (PRES) and those with PFS ≥ 12 months (long term responders, LR). The main aim is to determine clinical characteristics associated with primary resistance. Results: Among the 265 patients enrolled in the NPP, we identified 97 PRES (37%) and 71 LP (27%). Poor performance status, visceral metastases, presence of pain, low baseline haemoglobin level, increased LDH and ALP levels, and short time from diagnosis to AA therapy were significantly associated with early progression (Table). Conclusions: Several clinical parameters appear to correlate with early progression under AA. Their role as potential predictive factors of resistance deserve further exploration in order to develop alternative treatment strategies. [Table: see text]

Activity of new agents (NAs) as third-line treatment in metastatic castration-resistant prostate cancer (mCRPC) patients (pts) showing a primary resistance (PRes) to NAs-based second line therapy after docetaxel (DOC): Preliminary results from a multicenter Italian study

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Background: The androgen receptor machinery remains the ultimate target of NAs in mCRPC post-DOC, abiraterone acetate (AA), cabazitaxel (CAB), and enzalutamide (ENZ). It is postulated that some mechanisms of resistance may be common to all NAs. This may be crucial in planning their sequential use, mainly when a PRes to one of them is observed. The present study assessed the activity of NAs in pts who previously experienced a PRes to another NA administered after DOC. Methods: We collected data of pts who received sequentially two NAs after DOC in 32 Italian hospital. For each pt we recorded the clinical outcomes of all treatments received after DOC. For the study purpose, we consider with PRes all pts progressing within 3 months after second line NA start. All other pts were considered as without PRes. Results: A consecutive series of 271 mCRPC pts, median age 71 yrs (46-91), with bone (89%), nodal (56%) or visceral (19%) mets, was collected. All pts received NAs as second line after DOC (AA 54% – CAB 34%– ENZ 12%) and 54 (20%) showed a PRes. Among these, third line treatment [AA (31%), CAB (42%), and ENZ (27%)], produced a biochemical and an objective response rate of 11% in both cases, with a median progression free survival (PFS) and a median overall survival (OS) of 4 mos and 8 mos, respectively. No statistically significant differences were observed in terms of clinical outcomes on the basis of NA sequences (see Table). Conclusions: It appears from this preliminary data, that the activity of NAs in pts showing a PRes to second line NAs is very limited, regardless the NA is administered. [Table: see text]

Clinical Outcomes of Castration-resistant Prostate Cancer Treatments Administered as Third or Fourth Line Following Failure of Docetaxel and Other Second-line Treatment: Results of an Italian Multicentre Study

BACKGROUND

The availability of new agents (NAs) active in patients with metastatic castration-resistant prostate cancer (mCRPC) progressing after docetaxel treatment (abiraterone acetate, cabazitaxel, and enzalutamide) has led to the possibility of using them sequentially to obtain a cumulative survival benefit.

OBJECTIVE

To provide clinical outcome data relating to a large cohort of mCRPC patients who received a third-line NA after the failure of docetaxel and another NA.

DESIGN, SETTING, AND PARTICIPANTS

We retrospectively reviewed the clinical records of patients who had received at least two successive NAs after the failure of docetaxel.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The independent prognostic value of a series of pretreatment covariates on the primary outcome measure of overall survival was assessed using Cox regression analysis.

RESULTS AND LIMITATIONS

We assessed 260 patients who received one third-line NA between January 2012 and December 2013, including 38 who received a further NA as fourth-line therapy. The median progression-free and overall survival from the start of third-line therapy was, respectively, 4 mo and 11 mo, with no significant differences between the NAs. Performance status, and haemoglobin and alkaline phosphatase levels were the only independent prognostic factors. The limitations of the study are mainly due its retrospective nature and the small number of patients treated with some of the sequences.

CONCLUSIONS

We were unable to demonstrate a difference in the clinical outcomes of third-line NAs regardless of previous NA therapy.

PATIENT SUMMARY

It is debated which sequence of treatments to adopt after docetaxel. Our data do not support the superiority of any of the three new agents in third-line treatment, regardless of the previously administered new agent.

PSA flare with abiraterone in patients with metastatic castration-resistant prostate cancer

BACKGROUND

The aim of this study was to assess early serum prostate-specific antigen (PSA) changes in patients treated with abiraterone and to correlate those changes with clinical outcome.

PATIENTS AND METHODS

We retrospectively evaluated 103 patients with castrate-resistant prostate cancer (CRPC) treated with compassionate use of abiraterone in Romagna, Italy. In these patients, serum PSA levels were monitored every 4 weeks, and a time course of serum PSA levels was obtained. The PSA flare phenomenon was evaluated. The log-rank test was applied to compare survival between groups of patients according to early PSA level changes.

RESULTS

Of 103 patients, 43 (41.7%) had an immediate PSA response, whereas 9 (8.7%) had an initial PSA flare. Of the 9 patients with PSA flare, 5 attained a subsequent PSA response. The temporary PSA flare exceeded baseline values by a median of 19.7% (range, 5%-62.9%). The median PFS of the 9 patients in the PSA-flare group was higher compared with patients without the PSA flare (10.5 vs. 6.4 months; P = .0999) but was similar to the subgroup of patients with immediate PSA response (10.5 vs. 10.7 months; P = .7019). In the multivariate analysis, only the PSA response remained as a predictor of progression-free survival (PFS) (P < .0001) and overall survival (OS) (P = .0003), respectively.

CONCLUSION

PSA flare occurs not infrequently in patients with CRPC who respond to abiraterone. Patients should be informed of this possible PSA flare phenomenon.