Abstract P4-01-25: Safety analysis after 11 years of follow-up of the randomized phase III trial SAKK22/99: upfront chemotherapy in advanced HER2 positive breast cancer

Background: The SAKK 22/99 is a phase III randomized clinical trial launched by the Swiss Group for Clinical Cancer Research and the European Institute of Oncology in Milan in 99 for women with HER2-positive advanced breast cancer (ABC). 175 patients were randomized 1:1 from Sept 99 to Jan 2013 to receive first-line trastuzumab (T) alone followed at disease progression by the combination with chemo (Arm A) vs the upfront combination of T and chemo (Arm B). The results were published in 2017 (O. Pagani et al Ann Onc 28: 305–312, 2017). The outcome was similar for sequential T-chemo or upfront combination The patients’ treatment and FU continued until March 2022 and we now report the safety data after 135.2 months of median FU.

Patients and methods: at the time of study termination 1 patient with SD was still receiving T alone in the study and T was continued after trial closure. The safety analyses include 86 pts allocated to arm A and 88 to arm B. 1 pt did not receive any trial treatment and was excluded from this analyses. 19 of the 86 patients in arm A stopped trial treatment after T alone, 67 continued with T+ chemo. Baseline characteristics were well balanced and are summarized in Table 1. Treatment The T loading dose of 4 mg/kg/iv was followed by 2 mg/kg/iv weekly. In the 1st-line population (84) chemo was weekly paclitaxel (90 mg/m2/iv-3/4 weeks). After amendment 1 chemo was at investigator’s choice (taxanes, vinorelbine, platin) according to label indications and could be stopped after 24 weeks (6–8 cycles) in responding patients or after unacceptable toxicity.

Results: 7 patients in arm A (8%) and 11 in arm B (13%) stopped trial treatment due to toxicities (Fisher’s exact test, p=0.46). 3 of the 7 patients in arm A stopped under T alone and 4 under T+chemo (all paclitaxel weekly) Treatment durations of these 7 and 11 patients were 7.7 months (range 0.5 – 49) in arm A and 5.5 months (range 0.6 – 31 months) in arm B, respectively. Cardiovascular toxicities: The most common toxicities were thromboembolic events, blood pressure disorders and arrhythmia. 6 patients (7%) in arm A and 10 (11%) in arm B had cardiac events (Fisher’s exact test, p=0.43). G1-3 toxicities occurred in 2 (2%), 2 (2%) and 2 (2%) patients of arm A and in 5 (7%), 2 (2%) and 3 (3%) of arm B. We observed no grade 4 events. Split by treatment phase in arm A, G1-3 toxicities were seen in in 1 (1%), 2 (2%) and 1 (1%) patient under T alone (N=86) and in 1 (1%), 0 (0%) and 2 (3%) under T+chemo (N=67). LVEF-decline: 78 patients in arm A and 74 in arm B had sequential LVEF measurements. A decline ≥ 10% was found in 35 patients (45%) in arm A and in 20 (27%) in arm B (Fisher’s exact test, p=0.028). Among the 35 patients in arm A, 12 had the decline under T alone, 14 under T+chemo, and 9 under both T alone and T+chemo. A decline ≥ 20% was found in 10 patients (13%) in arm A and in 3 (4%) in arm B (Fisher’s exact test, p=0.08). Among the 10 patients in arm A, 7 had the decline under T alone, 3 under T+chemo. Sensory neuropathy 43 patients (50%) in arm A and 48 (54%) in arm B had neuropathy (Fisher’s exact test, p=0.65). G1-3 toxicity in arm A was developed by 26 (30%), 11 (13%) and 6 (7%) patients, respectively; in arm B 30 (34%), 12 (14%) and 6 (7%). No grades 4 events occurred. Conclusion: After more than 11 years of follow-up, no relevant toxicities were found in these patients receiving T for ABC. In particular, the incidence and grade of cardiac toxicity was low. The decline in LVEF was numerically higher in the arm A and in particular in the T alone group, but was not clinically relevant. Our data potentially suggest that T+chemo followed by T maintenance could have less cardiotoxicity than T followed by T+chemo. The possible causes for the difference in LVEF decline between the two arms are unclear, but could be related to treatment duration. The women in Arm A shows a trend to longer therapy: Median treatment duration (months) in Arm A was 7.92 (0.46 - 135.98) vs 6.62 (0.56 - 71.28) in Arm B. This long-term analysis confirms the favorable safety and good tolerability of the reported regimes.

Darolutamide Maintenance in Patients With Metastatic Castration-Resistant Prostate Cancer With Nonprogressive Disease After Taxane Treatment (SAKK 08/16)

PURPOSE

To assess the efficacy and safety of darolutamide maintenance after successful taxane chemotherapy in patients with metastatic castration-resistant prostate cancer (mCRPC).

PATIENTS AND METHODS

Swiss Group for Clinical Cancer Research (SAKK) 08/16 is a randomized phase II study. Patients with mCRPC who received prior androgen-receptor pathway inhibitors (ARPIs) and subsequently had nonprogressive disease on a taxane were randomly assigned to darolutamide 600 mg twice a day or placebo twice a day. The primary end point was radiographic progression-free survival (rPFS) at 12 weeks. Secondary end points were rPFS, event-free survival, overall survival (OS), prostate-specific antigen (PSA) 50% response rate, and adverse events.

RESULTS

Overall, 92 patients were recruited by 26 centers. Prior taxane was docetaxel in 93% and cabazitaxel in 7%. Prior ARPI was abiraterone in 60%, enzalutamide in 31%, and both in 9%. rPFS at 12 weeks was significantly improved with darolutamide (64.7% v 52.2%; P = .127). Median rPFS on darolutamide was 5.5 versus 4.5 months on placebo (hazard ratio [HR], 0.54; 95% CI, 0.32 to 0.91; P = .017), and median event-free survival was 5.4 versus 2.9 months (HR, 0.46; 95% CI, 0.29 to 0.73; P = .001). PSA 50% response rate was improved (22% v 4%; P = .014). Median OS for darolutamide was 24 versus 21.3 months for placebo (HR, 0.62; 95% CI, 0.3 to 1.26; P = .181). Treatment-related adverse events were similar in both arms.

CONCLUSION

SAKK 08/16 met its primary end point, showing that switch maintenance with darolutamide after prior taxane chemotherapy and at least one ARPI resulted in a statistically significant but clinically modest rPFS prolongation with good tolerability. The median OS with darolutamide maintenance appears promising. Should these findings be confirmed in a larger trial, maintenance treatment could be a novel strategy in managing patients with mCRPC, especially those who responded well to prior ARPI.

Olaparib plus abiraterone as first-line therapy in men with metastatic castration-resistant prostate cancer: Pharmacokinetics data from the PROpel trial

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Background: PROpel (NCT03732820) is a double-blind, Phase III trial of abiraterone + olaparib vs abiraterone + placebo as first-line treatment in patients with metastatic castration-resistant prostate cancer (mCRPC). Here we report results from the pharmacokinetics (PK) analysis of patients in PROpel. Methods: Patients were randomized 1:1 to receive abiraterone (1000 mg qd) plus prednisone/prednisolone with either olaparib (full monotherapy dose: 300 mg bid) or placebo. Eligible patients were biomarker unselected with confirmed prostate adenocarcinoma and castration-resistant metastatic disease. They had not received prior chemotherapy or next-generation hormonal agents (NHAs) for mCRPC. PK sampling was performed in a subset of patients. Concentrations of olaparib and abiraterone, and its active metabolite Δ4-abiraterone, were measured at steady state predose, at 30 min, 2 h, 3 h, 5 h, and 8 h postdose. The data underwent noncompartmental analysis to evaluate the effect of olaparib on abiraterone PK. The PK of olaparib in the presence of abiraterone was also compared with olaparib PK from other monotherapy studies to evaluate the effect of abiraterone on olaparib PK. Results: The PK analysis included 66 patients from the olaparib + abiraterone arm and 58 patients from the placebo + abiraterone arm. Olaparib absorption was rapid, with median tmax,ss of 2 h. Absorption of abiraterone was rapid in both treatment groups, with median tmax,ss observed between 2.00 and 2.04 h. The steady state exposure of olaparib in the presence of abiraterone, based on AUCss, Cmax,ss and Cmin,ss, was similar to observations for patients receiving olaparib 300 mg bid monotherapy in other Phase III studies, with values of 39.3 μg⋅h/mL, 6.3 μg/mL, and 1.0 μg/mL, respectively. Steady state exposures for abiraterone were similar between the two treatment arms (abiraterone + placebo: AUC(0–8) = 339.5 ng⋅h/mL, Cmax,ss = 105.4 ng/mL, Cmin,ss = 8.5 ng/mL; abiraterone + olaparib: AUC(0–8) = 393.7 ng⋅h/mL, Cmax,ss = 112.6 ng/mL, Cmin,ss = 7.7 ng/mL), and PK data for the abiraterone + olaparib arm were similar to those reported in the literature for abiraterone monotherapy. Conclusions: Combination treatment of olaparib ( full monotherapy dose: 300 mg bid) and abiraterone (1000 mg qd) in patients with mCRPC had no clinically significant effect on the PK profiles of either drug. The steady state exposures for abiraterone were similar between the two treatment arms, indicating that co-administration with olaparib 300 mg bid has no effect on the PK of abiraterone. In line with previous Phase II trial data, results from PROpel confirmed that there were no relevant PK based drug–drug-interactions between olaparib and abiraterone. Clinical trial information: NCT03732820.

Nivolumab in Combination with Stereotactic Body Radiotherapy in Pretreated Patients with Metastatic Renal Cell Carcinoma. Results of the Phase II NIVES Study

BACKGROUND

Nivolumab showed an overall survival (OS) benefit in pretreated metastatic renal cell carcinoma (mRCC). The role of stereotactic body radiotherapy (SBRT) in mRCC remains to be defined.

OBJECTIVE

Our aim was to evaluate the efficacy and safety of SBRT in combination with nivolumab in second- and third-line mRCC patients.

DESIGN, SETTING, AND PARTICIPANTS

The NIVES study was a phase II, single-arm, multicenter trial in patients with mRCC with measurable metastatic sites who progressed after antiangiogenic therapy, of whom at least one was suitable for SBRT.

INTERVENTION

The patients received SBRT to a lesion at a dose of 10 Gy in three fractions for 7 d from the first infusion of nivolumab. Nivolumab was given at an initial dose of 240 mg every 14 d for 6 mo and then 480 mg q4-weekly in responding patients.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We hypothesized that nivolumab plus SBRT improves the objective response rate (ORR) compared with nivolumab alone from 25% (derived from historical controls) to 40%. Secondary endpoints were progression-free survival (PFS), OS, disease control rate (DCR) of irradiated and nonirradiated metastases, and safety.

RESULTS AND LIMITATIONS

Sixty-nine patients were enrolled from July 2017 to March 2019. The ORR was 17% and the DCR was 55%. The median PFS was 5.6 mo (95% confidence interval [CI], 2.9-7.1) and median OS 20 mo (95% CI, 17-not reached). After 1.5 yr of follow-up, 23 patients died. The median time to treatment response was 2.8 mo and median duration of response was 14 mo. No new safety concerns arose.

CONCLUSIONS

We did not find sufficient evidence to suggest that nivolumab in combination with SBRT provides an added benefit in pretreated mRCC patients; it should however be evaluated in patients with oligometastatic or oligoprogressive disease.

PATIENT SUMMARY

Nivolumab in combination with stereotactic body radiotherapy does not provide evidence of increased outcomes in metastatic renal cell carcinoma patients. However this approach was safe and showed a good response of the irradiated lesions.

Programmed death ligand-1 (PD-L1) expression in patients (pts) with metastatic renal cell carcinoma (mRCC) treated with nivolumab (NIVO) in combination with stereotactic body radiotherapy (SBRT) in NIVES study

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Background: The NIVES study represents the first prospective trial with NIVO in combination with SBRT in pre-treated mRCC patients. This study did not meet the primary endpoint in terms of objective response rate (ORR) as previously reported. However this combination showed a faster time to treatment response, a long progression free survival and median duration of response without increasing toxicities. Here we have tested with an exploratory analysis the correlation between PD-L1 expression and clinical outcomes in pts treated with NIVO plus SBRT. Methods: PD-L1 expression was assessed in archival collected tumour samples in our central laboratory using 4 commercial kits for immunoistochemical (ICH) analysis (clone 22C3 pharm DX Dako Agilent, 28.8 Abcam and SP142 and SP263 Ventana Medical System). A tumor cell was considered positive if any membranous staining was found regardless of the intensity. In particular the immunostaining was scored 0 when all tumor cells were unstained (PD-L1-negative), 1+ when < 1% positive tumor cells were counted, 2+ when the percentage was between 1% and 50%,3+ when the number of stained cells was more than 50%. ORR and overall survival (OS) were correlated with PD-L1 staining. Results: Formalin-fixed paraffin-embedded (FFPE) specimens were obtained from 44 of 69 pts enrolled in the NIVES study. Twenty-two pts of 44 (50%) were considered PD-L1-negative using all the 4 commercial kits for ICH analysis, while 14 of 44 pts (31,8%) were defined PD-L1 weakly positive (positive tumor cells < 1% at least in one kit for ICH). Eight of 44 pts (18.1%) were defined PD-L1 strong positive when at least one kit for ICH scored 2+ or 3+. About the correlation between ORR and PDL1 staining in the 42 pts (2/44 pts are not evaluable for ORR), ORR was 18.2% (95% CI, 5.2% to 40.3%) in the PD-L1-negative group vs 20% (95% CI, 5.7% to 43.7%) in weakly/strongly PD-L1 positive (p = 1.00). Among the 44 pts in the intention-to-treat population with available PD-L1 status, median OS was not significantly different between pts with PD-L1 negative (20.56 months, 95% CI, 7.16 to NR) and PD-L1 positive (18.33 months, 95% CI, 6.83 to NR) (p = 0.56). Conclusions: For the first time four commercial kits for ICH analysis were used to test PD-L1 expression in pretreated mRCC pts. Data from these small sample size seem to confirm that PD-L1 in pre-treated mRCC cancer is not a predictive biomarker for selecting pts to receive NIVO-based treatment. Clinical trial information: NCT03469713.

Decreased fracture rate by mandating bone protecting agents in the EORTC 1333/PEACEIII trial combining Ra223 with enzalutamide versus enzalutamide alone: An updated safety analysis

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Background: The randomized phase III EORTC-1333-GUCG (NCT02194842) trial compares enzalutamide vs. a combination of Radium 223 and enzalutamide in asymptomatic or mildly symptomatic metastatic castration resistant prostate cancer (mCRPC) patients. The premature unblinding of ERA223 (NCT02043678) in Nov 2017 due to a significant increase in the rate of fractures in the combination of abiraterone and Ra223 arm led to the implementation of the mandatory use of bone protecting agents (BPA) in the EORTC-1333-GUCG trial. Skeletal fractures, pathological or not, are a frequent and underestimated adverse event of systemic treatment of advanced prostate cancer. Whether this mandated use of BPA (zoledronic acid or denosumab) would mitigate the risk of fractures in this patient population was unclear. An early safety analysis (Tombal, ASCO, 2019) suggested that the risk of fractures was well controlled in both arms when patients receive BPA. We present here an updated analysis of fracture incidence with longer follow-up. Methods: As of 28/01/2021, a total of 253 patients (134 after making BPA mandatory) were randomized between enzalutamide/Ra223 and enzalutamide. The fracture rate was estimated with the cumulative incidence method in the safety population of 237 (122 after making BPA mandatory) treated patients. Death in absence of fracture was analyzed as competing risk and censoring was applied at last follow-up. Results: Overall, 69.5% of enzalutamide/Ra223 patients (95.2% after making BPA mandatory) and 73.1% of enzalutamide patients (95% after making BPA mandatory) received BPA on treatment: 13.6% in the enzalutamide/Ra223 arm and 21.8% in the enzalutamide arm did not use BPA at registration, but started during protocol treatment and 55.9% and 51.3% respectively, received BPA since entry. At 36.7 months median follow-up in patients without BPA and 23.1 months median follow-up in patients receiving BPA, a total of 39 patients reported a fracture. Among them, 30 patients (20 in enzalutamide/Ra223 arm) did not receive BPA and 9 (4 in the enzalutamide/Ra223 arm) received BPA (see table). Conclusions: The updated safety analysis confirms the early fracture rate results. In the absence of BPA, the risk of fracture is increased when RA223 is added to enzalutamide. Strikingly, in both arms, the risk remains almost abolished by a preventive continuous administration of BPA, thus stressing the importance of complying to international recommendations in terms of giving BPA to mCRPC patients. This study is sponsored by EORTC and supported by Bayer and Astellas. Clinical trial information: NCT02194842. [Table: see text]

A phase 2 single-arm study of cabozantinib in patients with advanced or unresectable renal cell carcinoma pretreated with one immune checkpoint inhibitor: The BREAKPOINT trial (MeetUro trial 03-NCT03463681)

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Background: For many years, vascular endothelial growth factor (VEGF)-targeted therapy (tp) has been a milestone for metastatic renal cell carcinoma (mRCC). Recently, first line tp based on anti-PD-1/PD-L1 immune-checkpoint inhibitors (ICIs) plus tyrosine-kinase-inhibitors (IO-TKI) and anti-PD-1 plus anti-CTLA-4 combos (IO-IO) significantly improved survival of mRCC patients (pts). Prospective data are lacking to determine the efficacy of anti-VEGF tp after IO-IO or IO-TKI. Cabozantinib (Cabo) showed to prolong survival in mRCC pts pre-treated with TKIs and to target kinases involved in immune-escape. So, it may represent an ideal agent to be used sequentially after ICIs. Methods: This is an open label, single arm, multicenter, phase II study evaluating efficacy and safety of Cabo in mRCC pts who received an anti-PD-1/PD-L1-based adjuvant (adj) or first line tp. Cabo 60 mg/daily was administered until progressive disease (PD) or unacceptable toxicity. Primary endpoint was progression free survival (PFS) by Brookmeyer-Crowley test, secondary endpoints were overall survival (OS), objective response rate (ORR) and safety. Exploratory endopoints were to investigate tissue PD-L1 expression, to assess the modulating activity of Cabo on local and systemic tumor immunity and to explore bone formation and reabsorption markers. Results: From July 2018, 49 pts were enrolled and 48 were included in the analysis. Median age was 62.5 years (range: 30-78), 63% of pts were male. At baseline, 26% of pts had a good Heng risk score, 47% intermediate and 28% a poor risk, while in 2% of pts the class of risk was undetermined. 74% of pts received an IO-IO combo as first line tp, 17% IO-TKI, 9% pts an adj IO monotherapy. Pts received a median of 10 cycles of Cabo (range 5-17 cycles). 25 pts (53%) are still on tp, 1 patient discontinued Cabo for AEs, 13 pts for radiological PD, 6 pts discontinued for clinical PD or death, while 2 pts for reasons other than AEs or PD. Among evaluable cases, 17 pts (43%) achieved a partial response and 15 pts (37%) stable disease. Complete responses were not observed. At a median (m) follow-up of 8.0 months (mo) (4.4-13.5 mo), 71% of pts were alive and mPFS was 9.3 mo (95% CI 7.1-29.0 mo). Grade (G) 3-4 adverse events (AEs) occurred in 34% of pts, including more frequently serum bilirubin increase, hypertension, calcium and sodium serum levels alterations and oral mucositis. G1-2 were observed in 61% of pts, including in most of cases diarrhoea, nausea, oral mucositis, disgeusia, hand-foot syndrome, fatigue and hypothyroidism. Due to AEs, transitory withholding of Cabo was observed in 53.5% of pts and for 23 pts (48%) dose reductions were needed. Conclusions: So far, Cabo tp after IO-IO or IO-TKI showed promising results and was well tolerated. Longer follow-up is needed for final OS and exploratory endpoints results. Clinical trial information: NCT03463681.

A phase II open-label study of cabozantinib after first-line treatment including an immune-checkpoint combination in patients with advanced or unresectable renal cell carcinoma: The BREAKPOINT trial (MeetUro trial 03 - EudraCT number 2018-000582-36)

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Background: Antiangiogenic therapy has been a milestone in the treatment of metastatic renal cell carcinoma (mRCC) for years. The positive results with immune-checkpoint inhibitors (ICI) are changing the frontline standard of care of mRCC patients (pts). To date, prospective data are lacking to determine the efficacy of antiangiogenic therapy in pts progressed to ICI. The multikinase inhibitor Cabozantinib (cabo) has shown prolonged survival in pre-treated mRCC pts. Moreover, by targeting multiple pathways and crucial kinases involved in microenvironment-driven immune-escape, it may represent an ideal agent to be used sequentially after ICI. Methods: This is the first prospective open label, single arm, multicenter, phase II study to evaluate efficacy and safety of Cabo in pts with mRCC pre-treated with adjuvant or first line PD-1/PD-L1-based therapy (as monotherapy or in combination with an TKI or anti CTLA-4). Cabo 60 mg once daily was administered until progressive disease (PD) or unacceptable toxicity. The primary endpoint was progression free survival (PFS), secondary endpoints were overall survival (OS), objective response rate (ORR) and safety. Results: Among 23 patients enrolled, 22 were included in the analysis (one was excluded for screening failure). Median age was 59.5 years (range: 29-74), 69.5% were male. At baseline, Karnofsky performance status was 100 in 59% of pts, 80-90 in 31.8% and 70-80 in 9%. 22.7% of pts had a good Heng score, 50% intermediate and 27.2% poor. Median duration of the previous therapy with anti PD-1 or anti-PD-L1 compounds was 4.3 months. Pts received an average of 4.7 months of Cabo. Among evaluable cases, 6 pts (27.2%) achieved a partial response and 5 pts (22.7%) stable disease. The median follow-up was 7.2 months and the median PFS was 7.2 months. 2 pts discontinued treatment for toxicity, 8 pts for PD, 1 patient discontinued treatment for different reason than PD, 11 pts are still on treatment. Grade (G) 3 adverse events (AEs) occurred in 22.7% of pts; the most common AEs were hand and foot syndrome (HFS) (G1 in 36.3% of pts, G2 18.1%, G3 4.5%), diarrhea (G1 31.8%, G2 18.1%), hypothyroidism (G1 9.09 %, G2 22.7 %), mucositis (G1 36.3%, G2 4,5%), and fatigue (G1 18.1%, G2 18.1%). Transitory withholding of cabo was observed in 63.6% of pts (14/22) and it was due to AEs in the 90% of the cases. For 5/22 pts (22.7 %), dose reduction was needed to manage AEs. The most common AEs leading to temporary drug interruption were HFS G1-3 (13.9%), liver disfunction G1-G2 (13.9%), diarrhea G1-G2 (11.6%), nausea and vomiting G2 (11.6 %) and fatigue G2 (9.3%). Conclusions: So far, the treatment with cabo after a I line anti-PD-1 based immunotherapy resulted active and well tolerated. Clinical trial information: NCT03463681 .

Enzalutamide (E) re-challenge as second-line in metastatic castration-resistant prostate cancer (mCRPC) patients (pts) treated with first-line enzalutamide + docetaxel (D): Preliminary results of a post-progression analysis of CHEIRON trial

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Background: CHEIRON trial was a phase II study which randomized previously untreated mCRPC pts to receive D 75 mg/m2 IV d1 q3w for 8 courses alone or plus E 160 mg PO daily. As per protocol, E was administered in experimental arm for only 24 wks until D conclusion. The study met its primary endpoint since the rate of pts without disease progression at 6 mos was significantly higher in DE arm compared to D arm (89.1% vs 72.8%; p = 0.002). The clinicians were asked to consider an E re-challenge as first post-progression treatment for those pts without disease progression at the chemotherapy end in the experimental arm. We presented the preliminary analysis of E activity in post-progression setting of CHEIRON DE arm. Methods: We evaluated all patients enrolled in the experimental arm, focusing on pts who received E as first post-progression treatment. We collected data concerning the treatment duration and disease control and compared the outcomes of pts treated with E re-challenge with those of pts who received other treatments at the time of first progression after experimental therapy. Results: Among the 120 pts who received DE experimental arm, 101 did not show a disease progression and 82 received a second-line active treatment: 54 (66%) were treated with E, the other received abiraterone (10 pts), cabazitaxel (13 pts), and radium 223 (5 pts). The median interval between the end of DE and the start of E re-challenge was 7.6 mos (range 0.9-18.4 mos). At a median follow-up of 15.5 mos, the median duration of E re-challenge was 9.8 mos (range 1.9-30.9) with 22 pts still on treatment. Pts who received E rechallenge showed a median progression free survival of 11.4 mos which was significantly longer compared to 4.5 mos showed in pts who received other treatments (p < 0.0001). The median overall survival was 20.4 mos and 12.3 mos, respectively (p = NS). Conclusions: In pts who received first-line DE in the CHEIRON trial, the reintroduction of E after a per-protocol discontinuation demonstrated to be feasible, with a prolonged disease control compared to the other post-progression therapeutic options. Clinical trial information: NCT02453009.

Nivolumab (NIVO) in combination with stereotactic body radiotherapy (SBRT) in pretreated patients (pts) with metastatic renal cell carcinoma (mRCC): First results of phase II NIVES study

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Background: NIVO showed an increased on OS in pre-treated mRCC. The introduction of metastasis SBRT could improve the clinical outcomes. NIVES Study evaluated the efficacy and safety of SBRT in combination with NIVO in II and III line of mRCC pts. Methods: This is a phase II, single arm, multicentre study in mRCC pts with PD after ≤2 prior anti-angiogenic therapies with measurable metastatic sites, and at least one suitable for SBRT. The pts received hypofractionated radiation in 1 lesion at dose of 10 Gy/3 fractions after 7 days from the first infusion of NIVO. NIVO is given as flat dose of 240 mg on day 1 every 14 days for 6 months, then 480 mg q4-weekly in responding pts until PD or unacceptable toxicity. The primary end point is ORR. Secondary endpoints are PFS, OS, ORR of irradiated and non-irradiated metastasis and safety profile. Results: 69 pts were enrolled from July 2017 to March 2019 in 12 Italian centers. Pt characteristics were: 79.7% clear cell histology, 82.6% males, 79.7%% IMDC intermediate/poor, median age 67 yrs (43-85), 18.8% third line, 21.7% non-nephrectomy. The most frequent sites of SBRT were lung (37.7%), lymphonodes (15.9%), bone (11.6%). At the time of this analysis, median number of NIVO doses received was 12 (1-32). The ORR was 19% (1 CR) and DCR 63.5% (no statistically difference between site of SBRT and ORR); the largest benefit in pts with clear cell histology (p=0.01). Median PFS was 4 months (95%CI, 2.8-7.1), median OS 22.1 months (95%CI, 18.1-NR). With a median follow-up of 15 months (0-25.6), 6-month and 9-month survival rates were 80.3% and 56.1% respectively. 7 pts (10.1%) discontinued treatment due to AEs; grade(G) 3-4 toxicities related to NIVO were experienced in 17 pts (24.6%). The most frequent G3-4 toxicities included diarrhea (5.8%), amylase/lipase increased (4.3%) and hypothyroidism (4.3%); no G3-4 toxicities related to SBRT. Conclusions: The NIVES Study represents the first prospective trial of NIVO and SBRT combination in pre-treated mRCC pts. At present the Study showed a high DCR and no-increase of toxicity. It is ongoing the analysis of correlation between efficacy and PD-L1 expression. Clinical trial information: NCT03469713.

Decreased fracture rate by mandating bone-protecting agents in the EORTC 1333/PEACE III trial comparing enzalutamide and Ra223 versus enzalutamide alone: An interim safety analysis

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Background: Skeletal fractures, pathological or not, are a frequent and underestimated side-effect of systemic treatment of metastatic castration resistant prostate cancer (mCRPC). The ERA223 trial (NCT02043678) was recently unblinded following the report of a significant increase in the fracture rates when abiraterone is combined with Ra223. Hence, FDA and EMA advised against this combination. The question whether mandated use of bone protecting agents (BPA), zoledronic acid or denosumab, would have mitigated the fracture risk and whether this risk also exists in the enzalutamide/Ra223 combination is presently unknown. Methods: The phase III EORTC-1333-GUCG/PEACEIII (NCT02194842) trial compares enzalutamide vs. a combination of Ra223 and enzalutamide in asymptomatic or mildly symptomatic mCRPC patients (https://www.eortc.org/research_field/clinical-detail/1333/). After the unblinding of ERA223, the trial was amended (v4.0, April 19, 2018) to mandate that all patients must start a BPA. We report the fracture rate in the safety population of 146 treated patients as of 28/01/2019. Results: Overall, 54.2% of the patients in the enza/Ra223 arm and 51.4% of the enza arm did not receive BPA; 18.0% in the enza/Ra223 arm and 27.0% in the enza arm did not use BPA at randomization, but started during protocol treatment according to the v4.0 amendment. 27.8% and 21.6% respectively, received BPA as of randomization. In total, 45.8% of enza/Ra223 patients and 48.6% of enza only patients receive bone protection on treatment. The fracture rate is reported in the table. Conclusions: There is a 13% risk of fracture with enzalutamide in asymptomatic mCRPC, in line with previous reports. This risk is significantly increased to 33% when Ra223 is added to enzalutamide. Strikingly, the risk is almost abolished by mandatory continuous administration of BPA starting at least 6 weeks before the first injection of Ra223, thus emphasizing the importance of treating mCRPC patients with BPA. Clinical trial information: NCT02194842. [Table: see text]

A multicentric phase II randomized trial of docetaxel (D) plus enzalutamide (E) versus docetaxel (D) as first-line chemotherapy for patients (pts) with metastatic castration-resistant prostate cancer (mCRPC): CHEIRON study

5050

Background: D and E demonstrated to be efficacious in the treatment of mCRPC pts. Due to different antitumor mechanism of action of these agents, it could be postulated that their combination can improve disease control. CHEIRON study tried to demonstrate the candidate efficacy of chemo-hormonal combination D+E versus D in mCRPC first-line. Methods: Eligibility criteria included mCRPC diagnosis, ECOG PS ≤ 2, adequate renal, hepatic and hematological functions, no prior treatment for mCRPC. Pts were randomized to receive D 75 mg/m2 IV d1 q3w plus prednisone 5 mg PO BID for 8 courses alone or plus E 160 mg PO daily for 24 weeks. Stratification criteria were presence of pain and visceral metastases. The primary endpoint of the study was the rate of pts without disease progression (according to PCWG2) at 6 mos after randomization. Results: Between 09/2014 and 10/2017, 246 pts (median age 70 years, range 44-88, pain reported by 54 pts, visceral metastases present in 50 pts) were randomized to DE (120) or D (126). The rate of pts without disease progression at 6 mos was significantly higher in DE arm compared to D arm (89.1% vs 72.8%; p = 0.002). Similarly, a higher proportion of DE pts achieved a PSA reduction ≥ 50% compared to the baseline values compared to the D pts (92% vs 69%; p < 0.0001). No differences were observed in terms of objective response rate. Major haematological toxicities consisted of grade 3-4 neutropenia (13 pts DE – 11 pts D); febrile neutropenia was observed in 10 DE pts and in 6 D pts. At a median follow-up of 24 mos, the median progression free survival was 10.1 mos and 9.1 mos in DE and D arm, respectively (p = 0.01). In DE arm the median overall survival was 33.7 mos compared to 29.6 mos of the standard arm (p NS). Conclusions: The present study was the first phase II randomized trial, which tested the addition of a new generation hormone agent to D compared to D alone. From this data, DE improved the 6-mo disease control with a prolongation of PFS compared to the standard chemotherapy. Clinical trial information: NCT02453009.

Subgroup analysis from JAVELIN Renal 101: Outcomes for avelumab plus axitinib (A + Ax) versus sunitinib (S) in advanced renal cell carcinoma (aRCC)

544

Background: In the ongoing phase 3 JAVELIN Renal 101 trial, progression-free survival (PFS) was longer (median, 13.8 vs 8.4 mo; hazard ratio, 0.69; p=0.0001) and the objective response rate (ORR) was higher (51% vs 26%) with A + Ax vs S in patients with previously untreated aRCC. Here we report outcomes from an analysis of several prespecified subgroups. Methods: Patients were randomized 1:1 to receive A (10 mg/kg) IV every 2 weeks + Ax (5 mg) PO twice daily or S (50 mg) PO once daily for 4 wk (6-wk cycle). Primary and key secondary endpoints were PFS per independent review committee (IRC; RECIST v1.1) and OS in patients with PD-L1+ tumors (≥1% of immune cells) and in patients irrespective of PD-L1 expression; other secondary endpoints included OR per IRC (RECIST v1.1). Results: A total of 886 patients were randomized; 560 (63%) had PD-L1+ tumors. At data cut-off (Jun 2018), median follow-up was 12.0 vs 11.5 mo for A + Ax vs S groups. The table shows PFS and ORR by MSKCC and IMDC risk groups (F, favorable; I, intermediate; P, poor) and PD-L1 subgroup. Similar results for prognostic risk were seen in patients with PD-L1+ tumors. Outcome data (including PFS2) for additional clinical subgroups by baseline demographics and features will be presented. Clinical trial information: NCT02684006. Conclusions: A + Ax demonstrated PFS and OR benefit across all prognostic risk groups and PD-L1 subgroups vs S in aRCC.[Table: see text]

A phase II open-label study of cabozantinib in patients with advanced or unresectable renal cell carcinoma pretreated with one immune-checkpoint inhibitor: The BREAKPOINT trial

TPS685

Background: First-line treatment landscape of metastatic renal cell carcinoma (mRCC) is evolving with strong evidence in favour of PD-1/PD-L1 combinations over tyrosine kinase inhibitors (TKIs). No prospective data about efficacy of TKIs post immune-checkpoint inhibitor (CPI) combinations are available. Among TKIs, cabozantinib has demonstrated progression-free survival (PFS) and overall survival (OS) benefit over everolimus in pre-treated mRCC patients (pts). Methods: Overall 49 mRCC pts who received a previous CPI (anti PD-1/PD-L1) will be treated with cabozantinib. Pts will be stratified according to Heng prognostic group, duration of first-line and type of previous therapy received (CPI+CPI or CPI+TKI or CPI+anti-VEGF or CPI monotherapy). Key inclusion criteria include: one previous treatment with a PD-1/PD-L1 inhibitor in first-line and histological diagnosis of clear-cell RCC. The primary endpoint is to assess the efficacy of cabozantinib based on PFS. Secondary endpoints include evaluation of OS, objective response rate and safety profile of the drug. Exploratory endpoints include evaluation of PD-L1 levels by immunohistochemistry in tumor samples; the analysis of the immunological signature/profile of tumor cells; the state of circulating immune cells, as well as the modulating activity of cabozantinib on systemic tumor immunity; the evaluation of bone formation and reabsorption markers in pts with or without bone involvement. Cabozantinib will be administered orally at a dose of 60 mg/day continuously until evidence of disease progression or onset of unacceptable toxicity. Statistical design: By the methodology of Brookmeyer and Crowley, assuming an accrual period of 18 months and a minimum follow-up of 10 months (mos), 49 pts are necessary to detect an increment of the median PFS time from 3.8 mos to 7.4 mos with a power of 90% and one-sided alpha of 5%. The large sample critical value detecting the increment of the PFS median survival time will be 5.54 mos. To date, 2 pts have been enrolled. Clinical trial information: NCT03463681.

A multicentric phase II randomized trial of docetaxel (D) plus enzalutamide (E) versus docetaxel (D) as first-line chemotherapy for patients (pts) with metastatic castration-resistant prostate cancer (mCRPC): CHEIRON study

148

Background: D and E demonstrated to be efficacious in the treatment of mCRPC pts. Due to different antitumor mechanism of action of these agents, it could be postulated that their combination can improve disease control. CHEIRON study tried to demonstrate the candidate efficacy of chemo-hormonal combination D+E versus D in mCRPC first-line. Methods: Eligibility criteria included untreated mCRPC diagnosis, ECOG PS ≤ 2, adequate renal, hepatic and hematological functions. Pts were randomized to receive D 75 mg/m2 IV d1 q3w plus prednisone 5 mg PO BID for 8 courses alone or plus E 160 mg PO daily for 24 weeks. Stratification criteria were presence of pain and visceral metastases. The primary endpoint of the study was the rate of pts without disease progression (according to PCWG2) at 6 mos after randomization. Results: Between 09/2014 and 10/2017, 246 pts (median age 70 years, range 44-88, pain reported by 54 pts, visceral metastases present in 50 pts) were randomized to DE (120) or D (126). The rate of pts without disease progression at 6 mos was significantly higher in DE arm compared to D arm [87.3% (CI95% 64-80) vs 72.6% (CI95% 80-92); p = 0.006). Similarly, a higher proportion of DE pts achieved a PSA reduction ≥ 50% compared to the baseline values compared to the D pts [92.2%(CI95% 61-77) vs 70.0%(CI95% 86-96); p < 0.0001). No differences were observed in terms of objective response rate. Major haematological toxicities consisted of grade 3-4 anemia (3 pts DE – 1 pt D) and grade 3-4 neutropenia (23 pts DE – 19 pts D); febrile neutropenia was observed in 10 DE pts and in 5 D pts. At a median follow-up of 20 mos, the median progression free survival was 11.3 mos (CI95% 10.0-12.7) and 9.1 mos (CI95% 8.9-9.2) in DE and D arm, respectively (p = 0.004). In D arm the median overall survival was 30.5 mos (CI95% 24.1-36.8) compared to 28.7 mos (CI95% 20.7-36.6) of the experimental arm (p NS). Conclusions: From the present study, the first phase II randomized trial testing the addition of a new generation hormone agent to D, DE improved the 6-mo disease control with a prolongation of PFS compared to the standard chemotherapy. Clinical trial information: NCT02453009.

TARIBO trial: Cytoreductive nephrectomy in metastatic renal cell carcinoma patients treated with targeted agents

TPS4601

Background: In the cytokine era cytoreductive nephrectomy (CN) has been shown to increase survival in patients (pts) with metastatic renal cell carcinoma (mRCC). Efficacy of tyrosine kinase inhibitors (TKIs), including first-line sunitinib and pazopanib has been demonstrated. It is unclear if similar survival benefit could be achieved without CN with TKIs since most of pts enrolled into phase III trials had undergone CN. Methods: A total of 270 mRCC pts will be randomized to receiveCN followed by TKIs vs upfront TKIs without CN. Patients will receive pazopanib 800 mg orally daily or sunitinib 50 mg daily, 4 weeks on/ 2 weeks off. The choice of TKI will be done according to investigator’s clinical practice. Primary objective: to compare clinical benefit, as measured by overall survival (OS), provided by CN followed by TKIs vs upfront TKIs in pts with mRCC. Secondary objectives: i) to compare clinical benefit, as measured by progression-free survival (PFS) and response rate (RR) provided by CN followed by TKIs vs upfront TKIs; ii) Safety; iii) Exploratory analyses: evaluation of the predictive role of circulating tumor cells count and circulating tumor DNA at baseline, before and after surgery (in pts undergoing CN), 24 weeks after randomization and at the time of disease progression. Key inclusion criteria: Favorable or intermediate MSKCC or Heng prognostic risk group; histological diagnosis of RCC with a clear-cell component; resectable asymptomatic mRCC with primary tumor in place; up to three different metastatic sites; ≥ 3 metastatic lesions. Key exclusion criteria: Widespread disease ( > or = 4 metastatic organ sites); disease suitable of metastasectomy ( < 3 lesions confined at one organ site). Statistical plan: The sample size was calculated in order to compare 5-year OS between subjects randomized to receive CN followed by TKIs and those randomized to receive upfront TKIs. A total of 191 deaths will yield 80% power to detect a hazard ratio of 1.5 of upfront TKIs vs CN followed by TKIs with an overall type 1 error of 0.05 (two-sided log-rank test). Such a HR corresponds to an increase in the 5-year OS, from an anticipated value of 10% for TKIs to 21.5% for CN followed by TKIs. To date 10/270 pts have been enrolled. Clinical trial information: NCT02535351.

Dual modulation of MCL-1 and mTOR determines the response to sunitinib

Most patients who initially respond to treatment with the multi-tyrosine kinase inhibitor sunitinib eventually relapse. Therefore, developing a deeper understanding of the contribution of sunitinib's numerous targets to the clinical response or to resistance is crucial. Here, we have shown that cancer cells respond to clinically relevant doses of sunitinib by enhancing the stability of the antiapoptotic protein MCL-1 and inducing mTORC1 signaling, thus evoking little cytotoxicity. Inhibition of MCL-1 or mTORC1 signaling sensitized cells to clinically relevant doses of sunitinib in vitro and was synergistic with sunitinib in impairing tumor growth in vivo, indicating that these responses are triggered as prosurvival mechanisms that enable cells to tolerate the cytotoxic effects of sunitinib. Furthermore, higher doses of sunitinib were cytotoxic, triggered a decline in MCL-1 levels, and inhibited mTORC1 signaling. Mechanistically, we determined that sunitinib modulates MCL-1 stability by affecting its proteasomal degradation. Dual modulation of MCL-1 stability at different dose ranges of sunitinib was due to differential effects on ERK and GSK3β activity, and the latter also accounted for dual modulation of mTORC1 activity. Finally, comparison of patient samples prior to and following sunitinib treatment suggested that increases in MCL-1 levels and mTORC1 activity correlate with resistance to sunitinib in patients.

Abstract P2-08-08: Circulating tumor cells count-based nomograms to predict survival of metastatic breast cancer patients: Results from the European pooled analysis

Background: The European Pooled Analysis of CTC (EPAC) in metastatic breast cancer, based on 1,944 individual data from patients with various tumor types and clinical settings (Bidard et al, Lancet Oncol 2014), has established CTC count (CellSearch) at baseline and during therapy as a level of evidence 1 independent prognostic biomarker and demonstrated its superiority over serum blood markers. As part of the study pre-planned objectives, we sought to establish nomograms allowing accurate individual survival predictions.

Methods: Using individual data from 17 centers, we built simplified multivariate prognostic models taking into account the independent prognostic clinico-pathological (CP) characteristics including CTC count, dichotomized using the 5CTC/7.5ml threshold, at baseline and at 3-5 weeks after the start of a new treatment regimen, and derived nomograms for progression-free survival (PFS) and overall survival (OS) prediction at baseline and after 3-5 weeks of treatment. We report here the internal validation of these nomograms. Discrimination of the models was assessed using the c-index estimated by a jackknife procedure and the calibration was visually assessed through 10-fold crossvalidated calibration plots at 1,2,3 years for OS and 1,2 years for PFS.

Results: Multivariate models at baseline for PFS and OS were fitted on 1501 and 568 individual patient data with CTC count at baseline and CTC count at baseline and after 3-5 weeks, respectively. Models include tumor subtype, the number of previous chemotherapy lines (0/1/≥2), PS, age (&lt;=50/&gt;50-65/&gt;65 years), metastasis-free intervals (0/&gt;0-3/&gt;3 years), metastatic sites (liver and CNS) and CTC count at baseline and eventually at 3-5 weeks of treatment. The C-index increased from 0.722 to 0.755 (increase in C-index:0.033, 95% CI [0.019;0.045]) when adding baseline CTC to the CP only model for OS (n=1501). For those patients with CTC values at 3-5 weeks (n=568), there was an additional increase in the C-index when adding CTC at 3-5 weeks to a model with already CP and baseline CTC from 0.731 to 0.743 (increase in C-index 0.013, 95% CI [-0.004;0.025]). The model with CP and baseline CTC counts showed a good calibration for OS at 1,2,3 years and the model with CP, baseline CTC and CTC count at 3-5 weeks a moderately good calibration. Similar results were obtained for PFS.

Conclusion: From the largest database with individual CTC data, we were able to build PFS and OS survival nomograms, with satisfactory discrimination and calibration. Our planned next step is to validate the nomogram in an additional cohort.

Citation Format: Bidard F-C, Peeters D, Fehm T, Nole F, Gisbert-Criado R, Mavroudis D, Grisanti S, Generali D, Garcia-Saenz JA, Stebbing J, Caldas C, Gazzaniga P, Manso L, Zamarchi R, Fernandez de Lascoiti A, de Mattos-Arruda L, Ignatiadis M, van Laere SJ, Meier-Stiegen F, Sandri M-T, Vidal-Martinez J, Politaki E, Consoli F, Bottini A, Diaz-Rubio E, Krell J, Dawson S-J, Raimondi C, Rutten A, Janni W, Munzone E, Carañana V, Agelaki S, Almici C, Dirix L, Solomayer E, Zorzino L, Reis-Filho JS, Squifflet P, Pantel K, Beije N, Sleijfers S, Pierga J-Y, Michiels S. Circulating tumor cells count-based nomograms to predict survival of metastatic breast cancer patients: Results from the European pooled analysis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-08-08.

A personalized sunitinib (S) first-line approach in elderly patients with metastatic renal cell carcinoma (mRCC)

602

Background: About 24% of mRCC are older than 74 yo. S is a well-established first-line therapy for mRCC with a specific toxicity profile requiring a dose reduction in 30% of pts. Actually few data are available in the Literature about its use in patients > 75 yo especially as regards efficacy and cost effectiveness of tailored approaches. Methods: The primary end-point of this prospective single arm study, is to assess if a personalized approach is able to decrease the rate of dose reduction to 8% after the first cycle of S.. 19 pts have been estimated to be necessary to explore this hypothesis. Secondary objectives were the safety, treatment duration (TD) and overall survival (OS). Personalized approach was defined as the starting dose of S choose by the medical oncologist based on performance status (PS ECOG) and number of comorbidities. Results: From 2007 to 201421 pts were enrolled. The median age was 77.9 yrs (IQR 74.1-82.1). Seventy-five % had a clear cell carcinoma, 20% had a metastatic disease at diagnosis and 60% had > 2 sites of metastasis. All pts had PS ECOG ≥ 1 and 50% suffered from > 2 comorbidities. 43% were good, 52% intermediate and 5% poor prognosis by IMDC criteria. 3 pts (14%) started S at 50 mg/d, 9 pts (42%) at 37.5 mg/d and 9 pts (42%) started with 25 mg/d. All pts received S with the 4/2 schedule. The dose reduction after the first cycle was 28%. The reason was always toxicity, but no treatment interruption occurred. No pts starting at 25 mg had dose modification. The main toxicity requiring dose reduction was G3 anemia in 1pt, G3-4 thrombocytopenia in 3 pts and G3 leuconeutropenia in 3 pts . The median TD was 11.9 mos (95%CI, 6.5-17.3). The median OS was 33.3 mos (95%CI, 26.1-40.6). Conclusions: This study shows that a personalized starting dose is not able to decrease the rate of dose reduction at first cycle. Nonetheless a personalized strategy does not affect negatively the OS of elderly pts. Actually in elderly pts a disease stabilization without acute adverse events, could be considered an adequate goal. A well tolerated therapy could also be cost effective because part of health cost, especially for elderly pts, derives from their hospitalization for adverse events. Further data are required.

Impact of dose reduction on survival in patients starting sunitinib (SU) or pazopanib (PA) as first-line for metastatic renal cell carcinoma (mRCC)

553

Background: SU and PA are both VEGFR TKI approved for treatment of mRCC. Previous studies reported that the reduced dose (RD) is not recommended for the beginning of therapy (Motzer et al. 2012) and suggested a direct correlation between dose and effectiveness of therapy (Houk et al. 2010). We aim to investigate if patients (pts) that decreased the dose during treatment have different outcomes compared to those who continue a standard dose (SD). Methods: All pts affected by mRCC who started SU or PA at SD have been included. Pts were divided into two groups: RD and SD, based on whether they reduced the therapy or not. The main reasons for dose change have been collected and the RD group was defined into 2 levels (1st level: SU37.5mg/d, 4/2 or PA 600mg/d; 2nd level: SU25mg/d, 4/2 or PA 400mg/d). Pts were stratified by IMDC prognostic criteria and differences in pts’ characteristics between RD and SD groups were evaluated as well as median PFS and OS. Results: A total of 280 pts have been included. Median age was 62y and 68% was male; 54% had good prognosis, 40% intermediate and 6% poor. First-line was SU in 84% and PA in 16% of cases. A total of 123 (44%) pts decreased the dose to first- (89%) or second-level (11%). The main reasons were hand-foot syndrome (17.9%), diarrhea (15.4%) asthenia (14.6%), mucositis (13.0%) and thrombocytopenia (11.4%). Significant differences between RD and SD groups were the female sex (40% vs. 25%; p = 0.01) and the rate of primary refractory disease (11% vs. 31%: p < 0.001). Median PFS and OS were 12.4 and 34.9 mos, respectively. In RD group, the median time before dose reduction was 3.5 mos. Excluding the primary refractory pts, median PFS was 18.6 and 15.0 mos (p = 0.06) and median OS was 68.0 and 40.7 mos (p = 0.14) in RD and SD group, respectively. In RD group, no differences between 1st- and 2nd-level of dose were observed both in PFS (11.0 vs. 13.1 mos; p = 0.82) and OS (42.8 vs. 36.0 mos; p = 0.78) after reduction. Conclusions: Dose reduction is a frequent event in pts who started a first-line therapy with SU or PA. This study reports that DR does not affect the survival of pts who initially started SU and PA at standard dose.

Abstract PD6-5: Pooled analysis of circulating tumor cells in metastatic breast cancer: Findings from 1944 individual patients data

Background: Clinical validity of CTCs (CellSearch®) in metastatic breast cancer (MBC) patients has previously been assessed in studies with limited statistical power. We aimed to pool all European studies to obtain high-level evidence on the prognostic value of CTCs, to investigate their effects across different clinico-pathological characteristics and therapies and to further validate the MD Anderson/Institut Curie/Fox Chase CTC-based prognostic nomogram established in first-line treated MBC patients (Giordano et al, Clin Cancer Res 2013).

Material and methods: Methods were predefined in a written protocol. In December 2012, we searched for eligible studies that accrued patients in 2003-2012. We contacted all European laboratories using CellSearch®. We used likelihood ratio tests (LR) in Cox regression models stratified by study to assess the independent prognostic value of CTC when added to a clinicopathological (CP) model for progression-free (PFS) and overall survival (OS). Landmark analyses were used to assess the prognostic effect of early changes in CTC. The CTC-based nomogram (http://cancernomograms.com/CTCOnline.html) score was retrieved for every patient; we calculated C-indices, drew calibration plots and Kaplan-Meier curves according to quintiles of the nomogram score.

Results: We collected individual data of 1944 MBC patients, from 20 different studies (some unpublished), from 17 centers in 7 European countries. We observed 1507 PFS events and 929 deaths. Baseline CTC count was significantly associated with several patient characteristics, such as performance status (PS, p&lt;10-4), synchronous metastasis (p&lt;10- 2) tumor subtype (p&lt;10-4), liver & bone metastases (p&lt;10-4), CEA & CA15-3 levels (p&lt;10-4). The CP model for OS included PS, MBC subtypes, number of previous lines of treatment, patient's age, metastasis-free interval, metastatic sites (p&lt;0.01 for all). In a multivariate analysis containing the CP model parameters and CTC count at baseline, elevated CTC count (≥5) was a significant independent predictor of OS (n = 1444, HR = 2.7, 95%CI [2.2-3.2], LR p&lt;10-4). Baseline serum markers added either no or marginal effect to the CP plus baseline CTC model for OS. In contrast, early changes in CTC status at week 3-5 significantly added prognostic information for OS to the model with CP factors and baseline CTC+ (n = 569, HR = 1.8 [2.2-3.2], LR p&lt;0.001). In the population of interest (MBC treated by first line chemotherapy, n = 402 patients, 176 deaths), the CTC-based nomogram exhibited a good C-index for OS (0.69), was well calibrated and showed clear separation of the survival curves. Additional results, including subgroup analyses by tumor subtype and treatments will be presented at the meeting.

Conclusions: This pooled analysis is the largest study ever reported on CTC in MBC, with a previously unreached statistical power. It provides a clear level-of-evidence 1 on the independent prognostic value of CTCs before and during treatment in MBC. Also, the CTC-based prognostic nomogram is independently validated.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD6-5.

Detection of circulating tumor cells (CTCs) in stage T3-4 and/or N positive rectal cancer (RC) patients undergoing neoadjuvant therapy followed by curative surgery

e22078

Background: CTCs count at baseline and during treatment is an independent prognostic factor in metastatic colorectal cancer, while its role in early stages is still an open issue. No data are available in RC patients suitable for neoadjuvant chemoradiotherapy (CT-RT). Aim of the study: To investigate the role of CTCs in patients with locally advancedRC undergoing neo-adjuvant CT-RT. Methods: In a prospective single Institution study, cT3-4 and/or N+RC staged by rectal EUS and/or pelvic MRI and chest-abdomen CT scan, received capecitabine (825 mg/mq, orally, tid) with concurrent pelvic radiotherapy (50.4 Gy/28 fractions), followed by two cycles of intermittent capecitabine (1250 mg/mq, tid 14/21 days) and by low anterior resection or abdominopelvic resection with TME. Primary endpoints are evaluation of CTCs at baseline (t0), after CT-RT (t1), within 7 days after surgery (t2), and at 6-month from surgery (t3) and its correlation with main patient/tumor characteristics, CEA and response to neoadjuvant therapy. CTCs are enumerated with CellSearch System in 22.5 ml peripheral blood at over-mentioned time-points. A repeated measure analysis for binary outcome was used to evaluate changes in time of the percentage of patients with CTCs>0. Results: 85/90 patients are evaluable: 52M/33F, median age 63 yrs (range 37-82); median follow up 25 months (range 6-52). At baseline (t0) 13 pts had 1 CTC (15.3%), two had 2 CTCs (2.4%) and one had 27 CTCs(1.2%) while in 69 cases (81.2%) no CTCs were detected. Information on CTCs was available for 67 patients at t1, 68 patients at t2 and 62 at t3. CTCs>0 was reported on 16 (18.8%) at t0, 5 (7.5%) at t1, 6 (8.8%) at t2 and 3 (4.8% ) at t3 (P-value for trend: 0.039). CTCs at t0 was not statistically associated with any patient/tumor characteristics except for ultrasound T-stage that showed a trend CTCs (0% in uT2, 18.9% in uT3 and 40% in uT4, p-value 0.093), while no correlation with pCR was reported. Conclusions: CTCs count ≥ 1 was observed in 18.8% of patients with trend reduction over time probably due to therapy. Statistical correlation will be planned between CTCs and outcome.

A meta-analysis of receptor status discordance between primary breast cancer and metastases

546

Background: There is an increasing awareness that biology of breast cancer may evolve over time. The discordance in estrogen (ER), progesterone (PgR) and HER2 receptor status between primary breast cancer and metastases is being intensively investigated and a large amount of data has been produced. However, results from different studies seem to be conflicting and heterogeneous. To highlight this issue, a meta-analysis of published data was performed. Methods: A literature search was performed with Medline. All studies published from 1983 to 2011 comparing changes inER, PgR and/or HER2 status in patients with matched breast primary and recurrent tumors were included. We used random-effects models to estimate pooled discordance proportions. Results: We selected 42 articles, mostly reporting retrospective studies. Twenty-eight, 20 and 27 articles were focused on ER, PgR and HER2 changes, respectively. A total of 2806 tumors were evaluated for ER discordance, 1809 for PgR discordance and 2801 for HER2 discordance. The heterogeneity between study-specific discordance proportions was high (I2 >75%, p<0.0001) for ER, PgR and HER2. Pooled discordance proportions were 20% (95% CI: 16-25%) for ER, 33% (95% CI: 28-38%) for PgR and 9% (95% CI: 6-12%) for HER2. Pooled proportions of tumors shifting from positive to negative and from negative to positive were 24% and 12% for ER (p=0.0115), respectively. The same figures were 44% and 15% for PgR (p<0.0001), and 14% and 6% for HER2 (p=0.04). Conclusions: To our knowledge, this is the first meta-analysis addressing this topic. The findings strengthen the concept that changes in receptor expression may occur during the natural history of breast cancer and therefore clinical implications with possible impact on treatment choice cannot be excluded. However, the high heterogeneity observed in our analysis may explain the disagreement among oncologists on performing a reassessment of the biological features. In our opinion, only high-powered prospective and randomized trials could clarify the controversies in this field.

A prognostic model for predicting breast cancer (BC)-related survival in operable triple-negative (TN) patients (pts)

1049

Background: TNBC represent a heterogeneous disease in terms of biology, prognosis, and treatment response. We propose a prognostic model to identify homogeneous subgroups of patients and tailor risk-adapted adjuvant therapies indications. Methods: We analyzed 1,049 pts operated in our institute from 1997 to 2007 for early TNBC. Pts who received neoadjuvant chemotherapy (CT), with T4 tumors or previous history of cancer were excluded. Death from BC was the primary endpoint of the study. We calculated an individual predicted risk using a multivariable Cox regression model, with age, tumor size, number of positive lymph nodes and Ki-67 analyzed as continuous covariates, and tumor grade and perivascular invasion as categorical covariates. Results: Median age was 52 years, 562 (53.4%) and 670 (65.1%) pts had a pT1 and pN0 TNBC, respectively. Median Ki-67 was 48%. Adjuvant CT regimens were distributed as follows: classical CMF 388 (37.0%), anthracycline containing regimens 455 (43.4%), taxanes 12 (1.1%), other regimens 66 (6.3%) and no CT 128 (12.2%). After a median follow-up of 6 years, 131 deaths from BC were observed (5-year cumulative incidence 11.9%). At multivariable analysis, age, tumor size, number of positive lymph nodes, Ki-67, tumor grade and perivascular invasion were associated with the risk of death and were included in the prognostic model. Its predictive accuracy was good (C-index 0.73). We subsequently identified three homogeneous prognostic subgroups - low, medium and high-risk - according to the tertiles values of the predicted risk. The outcomes are shown in the table. Conclusions: We could identify homogeneous prognostic subgroups of TNBC pts according to clinical-pathological features. This prognostic model suggests that the use of CT in TN low-risk pts might be questionable. We are currently externally validating this model on a different series of pts. [Table: see text]

Role of breast surgery in T1-T3 breast cancer patients with synchronous bone metastases

1115

Background: The role of breast surgery in advanced breast cancer (ABC) is controversial. The main potential advantage of removing the primary tumor is to eliminate the source of further metastatic spread. While previous studies addressed the question in very heterogeneous populations (e.g. patients with any local and distant extension), we have focused on a homogeneous series of ABC patients. Methods: From our institutional Tumor Registry we selected 191 consecutive women diagnosed between 2000 and 2008 with locally operable (T1-T3) ABC, synchronous bone metastases and no other distant sites involved. The progression free survival (PFS) was calculated from diagnosis to the date of progression, defined as either a new site of metastatic disease or clinical/radiographic evidence of increasing tumor burden at a previously known bone metastatic site. Results: Median age was 51 years and 92% of the women had an endocrine-responsive tumor. One-hundred and thirty patients out of 191 (68%) underwent surgery at the time of diagnosis, while 61 (32%) did not. Twenty-six of the operated patients (20%) had previously undergone neoadjuvant chemotherapy; 15 (12%) had positive or undetermined surgical margins. Operated and non-operated patients were similar with respect to age, tumor size, nodal involvement, estrogen and progesterone receptor status, HER2 overexpression and Ki-67, but differed in terms of number of bone metastatic sites: a single metastasis was detected in 34 (26%) operated and 7 (11%) non-operated cases (P=0.02). First-line treatment strategies with endocrine therapy, chemotherapy and Trastuzumab were similarly distributed between the two groups. The 5-year PFS was 22.0% and 10.4% in operated and non-operated patients, respectively. The multi-adjusted hazard ratio was 0.62 (95% confidence interval 0.39-0.98) in favor of surgery. The exclusion of the patients who had received neoadjuvant chemotherapy and patients with positive or undetermined surgical margins did not alter the results. Conclusions: In this large and homogeneous series of ABC patients with synchronous bone metastases, the role of breast surgery had a favorable impact on the progression of the disease, indicating a potential survival benefit.

Cetuximab/radiotherapy (CET+RT) versus concomitant chemoradiotherapy (cCHT+RT) with or without induction docetaxel/cisplatin/5-fluorouracil (TPF) in locally advanced head and neck squamous cell carcinoma (LASCCHN): Preliminary results on toxicity of a randomized, 2x2 factorial, phase II-III study (NCT01086826)

5513

Background: The standard treatment options for LASCCHN are cCHT+RT or CET+RT. Strategies to improve the efficacy with the integration of induction chemotherapy are being investigated. Primary endpoints of this study were to compare: 1) the overall survival (OS) of induction vs. no induction arms; 2) the Grade(G)3-4 in-field toxicity of cCHT+RT vs. CET+RT. Methods: Patients (pts) with unresectable LASCCHN, stage III-IV, ECOG PS 0–1 were randomized to a 2x2 factorial design: Arm A1: cCHT+RT (2 cycles of ciplatin/5fluorouracil); Arm A2: CET+RTX; Arm B1: 3 cycles of TPF followed by the same cCHT+RT; Arm B2: 3 cycles of TPF followed by CET+RT. A total of 204 deaths over 420 pts ( including the 101 randomized in the phase II part of the study comparing cCHT+RT with or w/o induction TPF) were required to detect a HR of death of 0.675 (A1+A2 vs. B1+B2; 2-sided a=0.05; b=0.20) and a 10% difference in G3-4 in-field mucosal toxicity (A1+B1 vs. A2+B2). Results: By February 2012, 387 pts over 413 pts were evaluable for toxicity. 82% of pts were male; median age was 60y; PS: 0=77.8% and 1=22.2%. Disease stage was III (31%) or IV (69%). Sites of disease were oral cavity (21.7%), oropharynx (54.8%), hypopharynx (23.5%). At a median follow-up of 21 months, 126 deaths occurred. Data on G3-4 in-field toxicity (primary endpoint) and compliance to cCHT+RT vs CET+RT are shown in the table. Conclusions: No advantage for CET+RT over cCHT+RT was observed regarding G3-4 in-field toxicities and feasibility. Pts are still being followed-up to assess OS. [Table: see text]

Metastatic renal cell carcinoma (mRCC) in elderly patients: Can a personalized approach be an effective therapeutic option?

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Background: Renal cell carcinoma (RCC) is the third most common genitourinary cancer. Up to 30% of patients (pts) with RCC presents with advanced disease. Sunitinib(S), an orally available tyrosine kinase inhibitor, is the well established first-line therapy for these population. Actually few data are available in the literature about its use in patients > 75 yrs investigating the feasibility, the efficacy and the toxicity in this population.

Methods: From 2007 to 2011, 16 pts >75 yrs with mRCC received S. 75% of pts had a clear cell carcinoma, 87.5% had a surgery on primary tumor, 18.7% had a metastic disease at diagnosis and the median time to metastatic progression was 13.5 months. Median age was 78 years (range 71-88y).All patients had 0-1 performance status and 69% of them received S as first-line treatment. Four pts started S on the approved 50 mg /d 4-week-on-2-off schedule, but three of them reduced to 37.5 mg continuous once daily dosing(ODD)starting from the third cycle. Five out of 8 pts receiving 37.5 mg continuous ODD reduced the dose at 25 mg continuous ODD or modified the schedule. Four pts started with 25 mg continuous ODD and 2 of them continued the treatment at modified schedule. Median number of cycles administered was 7 (range 2-16).

Results: Response rate was 87% (13pts) in 15 evaluable pts. Overall response included 40% (6 pts) of PR, 20% (3pts) of CR, 33% (5pts) of SD > 6 mos. Progressive disease was observed only in 1patient. TTP was 12.4 months (95% CI, 4.8-32.6). Overall survival was 34.2 months (95% CI, 27.3- ). The main toxicity requiring dose reduction or schedule modification was haematological (46%), G3Anemia in 1 pt G3-4 thrombocytopenia in 3pts and G3 leukoneutrophenia in 3pts. No any toxicity required treatment interruption.

Conclusions: In summary these results show the feasibility and the efficacy of S in elderly population with high response rate regardless the doses and schedule used.

Circulating endothelial cells (CECs), progenitors (CEPs), and circulating tumor cells (CTCs) for prediction of response in patients with advanced breast cancer (ABC) receiving metronomic oral vinorelbine (oV): Preliminary results

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Background: Metronomic administration of chemotherapy given once or more per week with no extended gaps was shown to be effectively anti-angiogenic, causing growth arrest or apoptosis of endothelial cells in tumor neo-vessels. Preclinical and clinical studies indicate that ultra-low concentrations of various microtubule inhibitors inhibit proliferation or migration of endothelial cells. We investigated in a phase II study the activity of metronomic administration of oV in ABC, kinetics and response prediction of CECs, CEPs, CTCs and of other biomarkers of angiogenesis (soluble VEGF, VEGFr2, TSP1, bFGF). CT perfusion scans were also performed. Methods: From February 2008, 47 pts with ABC received oV (50 mg/die TTW). Currently 20 pts are evaluable for both activity and biomarker assessment. Baseline levels of biomarkers of angiogenesis were correlated with clinical response. Results: Shown in Table . Conclusions: We found that the baseline value of apoptotic cells (expressed as % of total cells) was significantly correlated with outcome. The baseline total, viable, and apoptotic CEC count and CTCs might provide an indirect measure for angiogenic turnover and an indicator of better response to anti-angiogenic therapy, supporting the use of metronomic treatments in patients expressing high levels of baseline CECs. Updated results will be presented together with correlation with perfusion CT scan and levels of CTCs.

[Table: see text]

No significant financial relationships to disclose.

Adjuvant therapy for very young women with breast cancer: response according to biologic and endocrine features

Incidence of breast cancer in patients aged < 20 years has been estimated to be 0.1 per 100,000 women. Reported incidences are 1.4 for women aged 20-24 years, 8.1 for women aged 25-29 years, and 24.8 for women aged 30-34 years. Younger patients have been found to have a more aggressive presentation of disease at diagnosis, which is associated with dire prognoses compared with those in premenopausal older patients. Several biologic features might explain the more aggressive behavior of breast cancer in younger patients: higher grade and higher expression of Ki67, higher occurrence of vessel invasion, and less expression of estrogen and progesterone receptors. Choice of adjuvant therapies for women aged <35 years with breast cancer is based on data derived from trials on cohorts of older patients. On average, the effect of chemotherapy for premenopausal patients is substantial: recent evidence suggested that very young women with endocrine-responsive tumors had a higher risk of relapse than older premenopausal patients with similar tumors. This was not the case for patients with endocrine-nonresponsive tumors, for which effects of chemotherapy were similar across ages. Very young women with this disease are faced with personal, family, professional, and quality-of-life issues that further complicate the phase of treatment decision-making. The development of more effective therapies for very young women with breast cancer requires tailored treatment investigations and research focused on issues specific to these patients.

Intrathecal chemotherapy in carcinomatous meningitis from breast cancer

Meningeal metastases occur in 2-3% of patients with breast cancer, leading to neurological morbidity and increased mortality. The criteria for treatment choice are controversial and intrathecal chemotherapy (ITC) has no documented role in the management of this disorder. We therefore evaluated the efficacy of an ITC regimen for patients presenting with carcinomatous meningitis from breast cancer.

PATIENTS AND METHODS

Patients with meningeal carcinomatosis with or without concomitant parenchymal brain metastasis, were treated with repeated courses of intrathecal chemotherapy according to the following alternated weekly schedule: Day 1: Thiotepa 10 mg, methotrexate 15 mg, hydrocortisone 30 mg; Day 5: cytarabine (Ara-C) 70 mg, methotrexate 15 mg, hydrocortisone 30 mg. Folinic acid 15 mg was given orally, every six hours after methotrexate on days 2-3 and 6-7.

RESULTS

Thirteen consecutive patients were treated. The median age was 45 (range 30-67) years. Eleven patients had performance status (PS) 2-3. Nine patients had other metastatic sites; synchronous parenchymal brain metastasis were present in 5 patients. Concomitant systemic chemotherapy was administered in 5 patients and external whole brain radiotherapy in 7 patients. With 12 evaluable patients we observed no responses or improvement in symptoms. Side-effects were minimal.

CONCLUSION

In our series of patients, ITC failed to provide objective response or relief in clinical symptoms. Despite evidence reported in the literature indicating symptomatic improvement after ITC in a number of patients with leptomeningeal metastasis, the results of our study confirm the controversial role of ITC. New drugs and new modalities of treatment should be studied in order to efficiently control meningeal involvement of breast cancer.