Talazoparib versus chemotherapy in patients with germline BRCA1/2-mutated HER2-negative advanced breast cancer: final overall survival results from the EMBRACA trial

BACKGROUND

In EMBRACA, talazoparib prolonged progression-free survival versus chemotherapy (hazard ratio [HR] 0.542 [95% confidence interval (CI) 0.413-0.711]; P < 0.0001) and improved patient-reported outcomes (PRO) in germline BRCA1/2 (gBRCA1/2)-mutated advanced breast cancer (ABC). We report final overall survival (OS).

PATIENTS AND METHODS

This randomized phase III trial enrolled patients with gBRCA1/2-mutated HER2-negative ABC. Patients received talazoparib or physician's choice of chemotherapy. OS was analyzed using stratified HR and log-rank test and prespecified rank-preserving structural failure time model to account for subsequent treatments.

RESULTS

A total of 431 patients were entered in a randomized study (287 talazoparib/144 chemotherapy) with 412 patients treated (286 talazoparib/126 chemotherapy). By 30 September 2019, 216 deaths (75.3%) occurred for talazoparib and 108 (75.0%) chemotherapy; median follow-up was 44.9 and 36.8 months, respectively. HR for OS with talazoparib versus chemotherapy was 0.848 (95% CI 0.670-1.073; P = 0.17); median (95% CI) 19.3 months (16.6-22.5 months) versus 19.5 months (17.4-22.4 months). Kaplan-Meier survival percentages (95% CI) for talazoparib versus chemotherapy: month 12, 71% (66% to 76%)/74% (66% to 81%); month 24, 42% (36% to 47%)/38% (30% to 47%); month 36, 27% (22% to 33%)/21% (14% to 29%). Most patients received subsequent treatments: for talazoparib and chemotherapy, 46.3%/41.7% received platinum and 4.5%/32.6% received a poly(ADP-ribose) polymerase (PARP) inhibitor, respectively. Adjusting for subsequent PARP and/or platinum use, HR for OS was 0.756 (95% bootstrap CI 0.503-1.029). Grade 3-4 adverse events occurred in 69.6% (talazoparib) and 64.3% (chemotherapy) patients, consistent with previous reports. Extended follow-up showed significant overall improvement and delay in time to definitive clinically meaningful deterioration in global health status/quality of life and breast symptoms favoring talazoparib versus chemotherapy (P < 0.01 for all), consistent with initial analyses.

CONCLUSIONS

In gBRCA1/2-mutated HER2-negative ABC, talazoparib did not significantly improve OS over chemotherapy; subsequent treatments may have impacted analysis. Safety was consistent with previous observations. PRO continued to favor talazoparib.

Correlation of extent of ALK FISH positivity and crizotinib efficacy in three prospective studies of ALK-positive patients with non-small-cell lung cancer

Background

In clinical trials of patients with anaplastic lymphoma kinase (ALK)-positive non-small-cell lung cancer (NSCLC) treated with crizotinib, evaluation of the relationship between the percentage of ALK-positive cells by fluorescence in situ hybridization (FISH)-particularly near the cut-off defining positive status-and clinical outcomes have been limited by small sample sizes.

Patients and methods

Data were pooled from three large prospective trials (one single-arm and two randomized versus chemotherapy) of crizotinib in patients with ALK-positive NSCLC determined by Vysis ALK Break Apart FISH using a cut-off of ≥15% ALK-positive cells. Logistic regression and proportional hazards regression analyses were used to explore the association of percent ALK-positive cells with objective response and progression-free survival (PFS), respectively.

Results

Of 11 081 screened patients, 1958 (18%) were ALK positive, 7512 (68%) were ALK negative, and 1540 (14%) were uninformative. Median percentage of ALK-positive cells was 58% in ALK-positive patients and 2% in ALK-negative patients. Of ALK-positive patients, 5% had 15%-19% ALK-positive cells; of ALK-negative patients, 2% had 10%-14% ALK-positive cells. Objective response rate for ALK-positive, crizotinib-treated patients with ≥20% ALK-positive cells was 56% (n = 700/1246), 55% (n = 725/1312) for those with ≥15% ALK-positive cells, and 38% for those with 15%-19% ALK-positive cells (n = 25/66). As a continuous variable, higher percentages of ALK-positive cells were estimated to be associated with larger differences in objective response and PFS between crizotinib and chemotherapy; however, tests for interaction between treatment and percentage of ALK-positive cells were not significant (objective response, P = 0.054; PFS, P = 0.17).

Conclusions

Patients with ALK-positive NSCLC benefit from treatment with crizotinib across the full range of percentage of ALK-positive cells, supporting the clinical utility of the 15% cut-off. The small number of patients with scores near the cut-off warrant additional study given the potential for misclassification of ALK status due to technical or biologic reasons.

A phase I dose escalation study of sunitinib in combination with gemcitabine + cisplatin for advanced non-small cell lung cancer (NSCLC)

18057

Background: Sunitinib malate (SU) is an oral, multitargeted tyrosine kinase inhibitor of VEGFRs, PDGFRs, KIT, RET, and FLT3, approved internationally for the treatment of advanced RCC and imatinib-resistant or -intolerant GIST. SU has also shown single- agent activity in NSCLC. In this study we assess the safety, tolerability, and pharmacokinetics (PK) of SU in combination with gemcitabine (G) and cisplatin (C). Methods: This is a phase I, dose-finding study in pts with untreated, stage IIIB/IV NSCLC not amenable to curative treatment. Planned dose levels include: oral SU (37.5 or 50 mg/day for 2 wks followed by 1 wk off treatment [2/1 schedule]) plus G (1000 or 1250 mg/m2 iv on days 1 and 8 of a 21-day cycle) and C (80 mg/m2 iv on day 1 of each cycle). SU doses are escalated in serial pt cohorts to determine the maximum tolerated dose (MTD) for both schedules. SU continuous dosing (CD) schedule will also be tested. PK and antitumor efficacy are also assessed. Results: As of Oct 2006, 13 pts were treated on the 2/1 schedule: 6 pts with SU 37.5 mg + G 1000 mg/m2 + C 80 mg/m2, and 7 pts with SU 50 mg + G 1000 mg/m2 + C 80 mg/m2. No dose-limiting toxicities (DLTs) were observed with SU 37.5 mg, while 2 pts experienced neutropenia and infection as DLTs with SU 50 mg. Grade 3/4 hematological AEs included neutropenia (n=3 at dose level 1 and n=5 at dose level 2), thrombocytopenia (n=1 and 5) and anemia (n=2 and 0). 3 pts achieved a partial tumor response at the SU 50 mg/day dose level. There were no apparent drug-drug interactions between SU in combination with G and C based on their systemic exposures in this study. Conclusions: The combination of SU (37.5 mg) on schedule 2/1 with G (1000 mg/m2) and C (80 mg/m2) in advanced NSCLC appears safe and tolerable in this pt population. Testing with G escalated to 1250 mg/m2 or with SU administered on a CD schedule is ongoing.

No significant financial relationships to disclose.

Sunitinib as second-line treatment for advanced gastric cancer: preliminary results from a phase II study

4603

Background: Sunitinib malate (SU) is an oral, multitargeted tyrosine kinase inhibitor of VEGFRs, PDGFRs, KIT, RET, and FLT3, approved internationally for the treatment of advanced RCC and imatinib-resistant or -intolerant GIST. We investigated the safety and activity of SU monotherapy in pts with previously-treated gastric cancer. Preliminary results from this open-label, multicenter, phase II study are reported. Methods: Eligibility criteria included measurable stage IV disease; 1 prior chemotherapy regimen; and ECOG PS =1. Pts took SU 50 mg/day for 4 wks followed by 2 wks off treatment in 6-wk cycles. A Simon 2-stage design was used with a target accrual of 38 pts in the first stage, expanding to 63 pts if =2 partial responses (PRs) were observed. The primary endpoint was RECIST-defined objective response rate. Secondary endpoints included duration of response and safety. Pharmacokinetic (PK) Ctrough parameters were also monitored. Results: As of Sept 15 2006, 38 evaluable pts (median age 56 years [range 29–78]; 2–3 metastatic sites [63%]; prior treatment with 5-FU ± platinum [P] [24%], capecitabine ± P [13%], TS-1 ± P [26%], other [37%]) have received a median of 2 SU cycles (range 1–3). Of 21 pts evaluable for efficacy, 1 PR has been confirmed and 8 pts had stable disease (SD), 4 with SD for =2 cycles. The most commonly reported AEs were typically grade 1/2 in severity and included stomatitis, skin discoloration, fatigue, anorexia, diarrhea, hand-foot syndrome (HFS), nausea and vomiting. Grade 3/4 toxicities included HFS (10.5%), fatigue (7.9%), anorexia (7.9%) and mucosal inflammation (5.3%). Grade 3/4 hematologic toxicities included neutropenia (29%), thrombocytopenia (29%) and anemia (11%). 7 pts experienced serious SU- related AEs requiring dose modifications in 3 pts and treatment discontinuation in 1 pt. Preliminary PK investigations indicate that concentrations seen in gastric pts are similar to those seen in other pts treated with SU. Conclusions: These initial findings show that SU is generally well tolerated and may have single-agent antitumor activity in pre-treated gastric cancer pts. Further trials with SU in combination with standard chemotherapy regimens are planned.

No significant financial relationships to disclose.

Assessment of safety and drug-induced tumor necrosis with sunitinib in patients (pts) with unresectable hepatocellular carcinoma (HCC)

3546

Background: VEGFRs and PDGFRs play key roles in the proliferation of HCC and tumor angiogenesis. Sunitinib malate (SU) is an oral, multitargeted tyrosine kinase inhibitor of VEGFRs, PDGFRs, KIT, RET and FLT3. This study reports the results of the first European/Asian, open-label, single-agent SU phase II study in pts with unresectable HCC. Methods: Key eligibility criteria include histologically confirmed measurable HCC; ECOG PS =1; Child-Pugh (CP)-A/-B; adequate organ function; and no brain metastases, ascites, or prior liver transplant. Pts receive SU at 50 mg/d for 4 wks every 6 wks (4/2 schedule). The primary endpoint is ORR by RECIST. Other assessments include safety (NCI CTCAE v3.0), PK and antitumor activity (tumor density, volumetric measurement of percent tumor necrosis [VMTN] and intratumor blood perfusion on monthly CT scan). Results: 37 pts (median 61 yrs [range 34–82]; male 92%; PS 0:1, 50%:44%; CP-A/-B, 84%/14%; 40.5% with prior local treatments) received a median of 2 cycles (range 1–7+) of SU. Grade 3–4 toxicities included thrombocytopenia (43%), neutropenia (24%), CNS symptoms (24%), asthenia (22%) and hemorrhage (14%). Grade 1–2 skin toxicity was frequently reported. Dose reductions were required in 27% of pts. Four pts developed grade 5 events including ascites, edema, bleeding, drowsiness and hepatic encephalopathy. Decreased tumor density was observed in 68% of pts and activity assessed by VMTN showed minor (<50%) and major (=50%) post-treatment tumor necrosis in 25% and 46% of pts, respectively. One confirmed PR and 39% SD (best confirmed response) have been achieved. Post-treatment tumor blood perfusion parameters (blood volume and blood flow), decreased by an average of 39% (range: 13–72%). Preliminary PK data do not suggest any differences in drug exposure between risk groups (CP-A or CP-B). Conclusions: Evidence of =50% tumor necrosis in 46% of pts receiving SU suggests outstanding antitumor activity. However, change in tumor size (RECIST) may be inappropriate as a primary endpoint to evaluate SU in patients with HCC. Initial safety findings indicate that further evaluation of SU in this pt population with improved pt selection and dose schedule modification is warranted.

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Safety, activity and estrogen inhibition by exemestane in postmenopausal women with advanced breast cancer: a phase I study

Exemestane is an irreversible, steroidal, oral aromatase inhibitor under evaluation in postmenopausal women with advanced breast cancer. A phase I study was conducted in 27 postmenopausal patients who were candidates for hormone therapy because they had advanced breast cancer and estrogen receptor-positive or unknown status. Most patients were moderately or heavily pretreated. Cohorts of at least three patients received sequentially escalating daily oral doses of 5-600 mg. The median duration of exemestane treatment was 13 weeks (range: 3-166 weeks). The maximal tolerated dose was not reached because of lack of treatment-related grade 3 or 4 toxicity. The most common adverse events, including those not related to treatment, were mild to moderate headache (44% of patients), dizziness (33%), nausea (33%), hot flushes (30%) and tumor-related pain (30%). There were three complete and four partial responses for an objective response rate of 26% (95% CI: 11.1-46.3%) in the intent-to-treat population; the median duration of response was 74 weeks (95% CI: 48-99 weeks). Exemestane, at the dose of 25 mg, maximally suppressed estradiol, estrone and estrone sulfate serum levels to 13, 5 and 10% of baseline, respectively. Exemestane appears to suppress estrogen, be well tolerated and have antitumor activity in postmenopausal women with advanced breast cancer. A large, safe therapeutic window of up to 600 mg was defined. In view of its safety and estrogen-suppression profiles, the most favorable effects were observed at the 25 mg daily dose.

Third-line hormonal treatment with exemestane in postmenopausal patients with advanced breast cancer progressing on aminoglutethimide: a phase II multicentre multinational study. Exemestane Study Group

In a European multicentre phase II study, 80 postmenopausal patients (pts) with advanced breast cancer progressing on aminoglutethimide (AG) at daily doses of > or = 500 mg were enrolled. Seventy-eight received exemestane (200 mg daily orally), including 33 pts resistant to prior AG, 39 pts who had progressed after an initial response to AG, and 6 pts whose response to AG was either unavailable or not evaluable. Three pts were pretreated with AG only, 69 with tamoxifen and AG, and 6 with tamoxifen, AG and other hormone therapies; 55% had also previously received chemotherapy. The predominant site of disease was visceral in 34 cases, bone in 27 and soft tissue in 17. Based on Peer Review assessment, the overall objective response rate (CRs plus PRs) was 26% (12% in pts resistant to AG and 33% in AG-responsive pts). Disease stabilisation > or = 24 weeks was achieved in an additional 13% of patients (15% of those resistant to AG and 13% of those AG-responsive), resulting in an overall success rate of 39% (28-50, 95% confidence interval). The median duration of objective response, overall success and median TTP were 59, 48 and 21 weeks, respectively. Toxicities were usually mild to moderate in severity, with hot flushes (21%), nausea (19%), dizziness (12%), weakness (12%), increased sweating (12%), androgenic symptoms (10%) and peripheral oedema (9%) as the most common side-effects. Only 2 pts (3%) discontinued treatment due to adverse events. These results are very promising considering that exemestane was administered as third- or fourth-line hormonal treatment in most cases and confirm previous observations about the lack of cross-resistance when steroidal aromatase inhibitors are sequenced with the non-steroidal aromatase inhibitor AG.