Annual Meeting Proceedings Part 1 - American Society of Clinical ...
Annual Meeting Proceedings Part 1 - American Society of Clinical ...
Annual Meeting Proceedings Part 1 - American Society of Clinical ...
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508 <strong>Clinical</strong> Science Symposium, Sat, 1:15 PM-2:45 PM<br />
A phase I/IB dose-escalation study <strong>of</strong> BEZ235 in combination with<br />
trastuzumab in patients with PI3-kinase or PTEN altered HER2� metastatic<br />
breast cancer. Presenting Author: Ian E. Krop, Dana-Farber Cancer<br />
Institute, Boston, MA<br />
Background: Alterations in the PI3K/AKT/mTOR pathway have been implicated<br />
in resistance to trastuzumab (T) in HER2� breast cancer. BEZ235, a<br />
potent oral dual PI3K/mTORC1/2 inhibitor, has demonstrated growth<br />
inhibition and apoptosis in HER2� breast cancer models, including those<br />
harboring PI3K pathway alterations, and with T resistance. In a Phase I<br />
study, BEZ235 was well tolerated as a single agent in pts with advanced<br />
solid tumors. The aim <strong>of</strong> this study was to determine the MTD <strong>of</strong> BEZ235 in<br />
combination with T in pts with T-resistant HER2� metastatic breast cancer<br />
(mBC) with alterations <strong>of</strong> the PI3K pathway. Methods: Pts with T-resistant<br />
HER2� mBC (i.e. disease progression during adjuvant therapy or metastatic<br />
disease on therapy with T) received oral BEZ235 daily, with weekly T<br />
(2 mg/kg). Pts were eligible for enrollment if a tumor sample was<br />
demonstrated to contain a molecular alteration <strong>of</strong> PIK3CA and/or PTEN.<br />
Dose escalation was guided by a Bayesian logistic regression model with<br />
overdose control. Results: As <strong>of</strong> 23 Sep 2011, 15 <strong>of</strong> the 19 enrolled pts<br />
were evaluable for dose escalation analysis. BEZ235 was evaluated at 3<br />
dose levels: (1) 400 mg/day (3 pts); (2) 600 mg/day (6 pts); (3) 800<br />
mg/day (10 pts), administered either in capsule form (400 mg) or in sachet<br />
form (600 mg and 800 mg). The MTD <strong>of</strong> BEZ235 in combination with T<br />
was estimated to be 600 mg/day. Observed DLTs were G3 nausea at 600<br />
mg/day (1 pt), and G3 nausea, G3 fatigue and G3 skin rash (1 pt each) at<br />
800 mg/day. The most frequent G3/4 adverse events (CTCAE v3.0)<br />
suspected to be related to study treatment were diarrhea (4 pts) and nausea<br />
(2 pts). No deaths related to study treatment occurred. 1 pt with lung and<br />
brain metastases had a partial response. 4 pts had disease stabilization for<br />
�4 cycles (16 weeks), including 1 pt with liver metastases, in whom<br />
BEZ235/T treatment resulted in disease stabilization for more than 21<br />
cycles (84 weeks). Conclusions: BEZ235in combination with T demonstrated<br />
an acceptable safety pr<strong>of</strong>ile in pts with HER2� mBC and PI3K<br />
pathway alterations. Following the Bayesian model recommendation, the<br />
MTD for BEZ235 in combination with T was estimated to be 600 mg/day.<br />
The safety expansion arm is ongoing at the MTD.<br />
510 <strong>Clinical</strong> Science Symposium, Sat, 1:15 PM-2:45 PM<br />
SU2C phase Ib study <strong>of</strong> pan-PI3K inhibitor BKM120 with letrozole in ER�/<br />
HER2- metastatic breast cancer (MBC). Presenting Author: Ingrid A. Mayer,<br />
Vanderbilt-Ingram Cancer Center, Nashville, TN<br />
Background: Mutations in PIK3CA, the gene encoding the p110a subunit <strong>of</strong><br />
PI3K, have been associated with antiestrogen resistance in ER� BC. In general,<br />
antiestrogen-resistant cancers retain ER and responsiveness to estradiol. This<br />
suggests that treatment <strong>of</strong> ER�/PI3K mutant BC should include PI3K inhibitors<br />
plus antiestrogens. Methods: We conducted a phase Ib trial <strong>of</strong> letrozole (2.5<br />
mg/d) with the pan-PI3K inhibitor BKM120 in post-menopausal patients (pts)<br />
with ER�/HER2 MBC. BKM120 (100 mg/d) was given continuously (Arm A) or<br />
intermittently (5 on/2 <strong>of</strong>f days; Arm B). Upon toxicity, BKM120 was reduced to<br />
80 and 60 mg/d. Treatment continued until unacceptable toxicity or disease<br />
progression. Disease was assessed every 2 months. FDG-PET was done at<br />
baseline and at 2 weeks in all pts in Arm A. Results: Fifty-one pts were accrued;<br />
49 had progressed on an AI previously. Median age was 56 years (range 34-77);<br />
95% had bone and 70% visceral metastases. Toxicities and outcomes are<br />
summarized in the table. The only DLT* in Arm A and B were transaminitis and<br />
depression, respectively; both at 100 mg. Over 50% <strong>of</strong> Arm A pts had �25%<br />
reduction in their peak SUV at the 2-week FDG-PET. Pts who did not exhibit a<br />
metabolic response by FDG-PET progressed rapidly on therapy. Three pts in Arm<br />
A had a PI3K mutation; one <strong>of</strong> them has had stable disease on treatment for �12<br />
months. Conclusions: The combination <strong>of</strong> letrozole/ BKM120 is safe in pts with<br />
AI-refractory ER�/HER2 MBC. Arm B is ongoing and will be updated at the<br />
meeting. All tumor biopsies will be analyzed for PI3K pathway alterations.<br />
FDG-PET at 2 weeks appears to be a useful pharmacodynamic biomarker <strong>of</strong> PI3K<br />
pathway inhibition in most patients. Its value in predicting treatment response<br />
remains to be determined.<br />
ArmA(N�20) Arm B (N�31)<br />
Grade (%)<br />
Grade (%)<br />
Toxicity<br />
1 2 3 Total 1 2 3 Total<br />
Hyperglycemia 50 10 10 70 16 3 0 19<br />
Nausea 55 10 0 65 12 0 0 12<br />
Fatigue 25 40 5 70 9 3 0 12<br />
Transaminitis 35 25 15* 75 16 6 6 16<br />
Diarrhea 40 10 0 50 19 0 0 19<br />
Anxiety 25 15 5 45 3 3 0 6<br />
Depression 15 35 5 55 3 6 3* 12<br />
Rash 30 0 5 35 3 0 0 3<br />
Outcomes Arm A (N�20) Arm B (N�31)<br />
CR 1 0<br />
PR 1 0<br />
SD >4 months 9 4<br />
PD 7 8<br />
Non-evaluable 2 5<br />
Still on treatment 1 17<br />
Median TTP (months) 4 (2-11) N/A<br />
Discontinued due to toxicity 6 3<br />
Treatment > 8 weeks without interruption 17 N/A<br />
Breast Cancer—HER2/ER<br />
509 <strong>Clinical</strong> Science Symposium, Sat, 1:15 PM-2:45 PM<br />
PI3K pathway (PI3Kp) dysregulation and response to pan-PI3K/AKT/mTOR/<br />
dual PI3K-mTOR inhibitors (PI3Kpi) in metastatic breast cancer (MBC)<br />
patients (pts). Presenting Author: Mafalda Oliveira, Breast Cancer Group,<br />
Vall d’Hebron University Hospital, Barcelona, Spain<br />
Background: The role <strong>of</strong> PI3Kp dysregulation as a predictor <strong>of</strong> sensitivity to<br />
PI3Kpi is unclear. We aimed to evaluate the efficacy <strong>of</strong> PI3Kpi in two<br />
cohorts <strong>of</strong> MBC pts with assessable PI3Kp status. Methods: MBC pts<br />
treated in �3rd line with PI3Kpi were reviewed. PI3Kp status: (a) No<br />
dysregulation: PIK3CA wt and PTEN normal; (b) PI3Kp dysregulation:<br />
PIK3CA mutation (PIK3CAmut) or PTEN low (HScore�50). Cohort A: pts<br />
treated with single agent PI3Kpi. Cohort B: pts treated with PI3Kpi in<br />
combination with hormonal therapy (HT), chemotherapy (CT) and/or<br />
trastuzumab (T). Results: Out <strong>of</strong> 232 MBC pts screened for PI3Kp<br />
alterations from Sep09 to Sep11, 32 were treated with PI3Kpi. Cohort A<br />
(n�17): HR�/HER2- 88%, HER2� 6%, triple negative 6%; median age<br />
43, median MBC lines 4 (2-9); PIK3CAmut in 10/17 (58.8%; 6 exon9, 4<br />
exon20), PTEN low 3/17 (17.6%), 1 pt both; PI3Kp dysregulation 12/17<br />
pts. Cohort B (n�15): HR�/HER2- 40%, HER2� 60%; median age 49,<br />
median MBC lines 4 (2-13); PIK3CAmut 3/13 assessable (23.1%; all<br />
exon20), PTEN low 6/15 (40%), 1 pt both; PI3Kp dysregulation 8/15 pts.<br />
Time to progression to PI3Kpi (TTP), overall survival from MBC diagnosis<br />
(OSMBC) and OS from PI3Kpi beginning (OSPI3Kpi), according to PIK3CA<br />
status and PI3Kp dysregulation, are shown. No differences were found<br />
according to PTEN status. Conclusions: These results suggest that the best<br />
outcomes with PI3Kpi in PIK3CAmut MBC pts occur when they are used in<br />
combination with HT/CT/T. Activity <strong>of</strong> non selective PI3Kpi used as single<br />
agents seems to be limited, making results from prospective trials with<br />
selective PI3K� inhibitors and PI3Kpi in combinations eagerly awaited.<br />
Months<br />
Median<br />
(95%CI)<br />
Cohort A<br />
n�17<br />
TTP<br />
OSMBC<br />
OSPI3Ki<br />
Cohort B<br />
n�15<br />
TTP<br />
OSMBC<br />
OSPI3Ki<br />
PIK3CA PI3Kp dysregulation<br />
WT Mut p No Yes p<br />
n�7 n�10 n�5 n�12<br />
7.4<br />
(3.5-11.2)<br />
95<br />
(0-206.9)<br />
NR<br />
1.4<br />
(0-3.6)<br />
47.1<br />
(12.4-81.9)<br />
8.5<br />
(2.8-14.2)<br />
0.026<br />
0.217<br />
0.048<br />
4.9<br />
(1.5-8.2)<br />
95<br />
(-)<br />
NR<br />
1.4<br />
(0-3.3)<br />
47.1<br />
(13.6-80.7)<br />
5.7<br />
(1.8-9.5)<br />
n�10 n�3 n�7 n�8<br />
3.6 (1.2-6.1)<br />
NR<br />
NR<br />
8.4 (-)<br />
NR<br />
NR<br />
0.053<br />
0.212<br />
0.223<br />
3.6 (0.7-6.6)<br />
55.7 (53.5-57.8)<br />
5.9 (2.6-9.2)<br />
3.7 (2.2-5.2)<br />
NR<br />
NR<br />
0.092<br />
0.097<br />
0.039<br />
0.451<br />
0.216<br />
0.306<br />
511 Poster Discussion Session (Board #1), Sat, 1:15 PM-5:15 PM and<br />
4:45 PM-5:45 PM<br />
Randomized trial <strong>of</strong> marker-directed versus standard schedule zoledronic<br />
acid for bone metastases from breast cancer. Presenting Author: Robert<br />
Edward Coleman, CR-UK/YCR Sheffield Cancer Research Centre, Sheffield,<br />
United Kingdom<br />
Background: Zoledronic acid (ZOL) reduces skeletal morbidity associated<br />
with metastatic bone disease by 30-50%. Current recommendations are for<br />
indefinite administration <strong>of</strong> intravenous 3-4 weekly (w) ZOL 4mg. Over<br />
recent years it has become clear that the risk <strong>of</strong> skeletal morbidity is related<br />
to the rate <strong>of</strong> bone resorption. We have compared a marker directed<br />
schedule <strong>of</strong> ZOL (M-ZOL), using measurements <strong>of</strong> urinary n-telopeptide <strong>of</strong><br />
type I collagen (NTX), to a standard treatment schedule (S-ZOL) in patients<br />
with bone metastases from breast cancer. Methods: The primary endpoint<br />
was skeletal related events (SRE). A non-inferiority study was designed with<br />
80% power and (one-sided) 5% alpha to demonstrate that M-ZOL retained<br />
67% <strong>of</strong> the efficacy <strong>of</strong> S-ZOL. This required 1500 patients, assuming a<br />
SRE rate <strong>of</strong> 0.7/year. Following minimisation for known prognostic factors,<br />
patients were randomised to receive S-ZOL 3-4 w or M-ZOL (15-16w; 8-9 w<br />
or 3-4w if NTX levels were �50, 50-100, �100 nmol/mmol creatinine<br />
respectively), with the schedule adjusted according to NTX measured every<br />
16 weeks. The study duration was 24 months. Results: Due to lower than<br />
expected recruitment, the study closed in 2009 following recruitment <strong>of</strong><br />
289 patients. 90% <strong>of</strong> patients had received �4 cycles <strong>of</strong> ZOL or<br />
pamidronate prior to randomisation. The median number <strong>of</strong> ZOL infusions<br />
administered to S-ZOL patients was �2x that received on M-ZOL. 46<br />
(32%) S-ZOL and 55 (38%) M-ZOL patients experienced an SRE. The<br />
numbers <strong>of</strong> SRE were 94 and 138 in the S-ZOL and M-ZOL arms, with the<br />
excess in SRE being largely due to more patients on M-ZOL experiencing<br />
�2 SRE. Multivariate analysis adjusting for key minimisation factors and<br />
baseline NTX for all SRE showed a hazard ratio for M-ZOL vs. S-ZOL <strong>of</strong> 1.41<br />
(90%CI 0.98-2.02, p�.12). NTX levels were significantly higher at all time<br />
points in the M-ZOL treated patients. Osteonecrosis <strong>of</strong> the jaw was<br />
uncommon with 3 cases with S-ZOL and 1 with M-ZOL. Conclusions: The<br />
study is underpowered to demonstrate non-inferiority in SRE outcome<br />
between the treatment strategies. However, the results suggest that the<br />
adjustment <strong>of</strong> ZOL schedule based on NTX values alone may represent<br />
sub-optimal management.<br />
Visit abstract.asco.org and search by abstract for the full list <strong>of</strong> abstract authors and their disclosure information.<br />
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