Mutant PIK3CA Is Detected in Both Pre-Invasive and Recurrent Breast Cancer

BackgroundWe identified somatic PIK3CA mutations in 32.5% of 590 primary invasive breast cancers (BC) (manuscript in press: Clinical Cancer Research). Detected by massARRAY genotyping, PIK3CA mutations significantly associate with favorable clinicopathologic features and improved clinical outcome, including overall and breast cancer-specific survival. Given the strong association between PIK3CA mutations and hormone receptor (HR) positivity, one hypothesis is that PIK3CA mutations 'drive' HR positive BC and will be detected in pre-invasive breast tumors. As PIK3CA mutations offer a protective effect in BC, it has not been determined whether PIK3CA mutations are selected for in disease progression or whether additional collaborating mutations are required.MethodsTo determine the concordance of PIK3CA mutations and assess the acquisition of additional oncogene mutations, available matched tissue samples, from the previous database, were procured and underwent massARRAY genotyping (n = 83). Two mm cores were macro-dissected from matched formalin-fixed, paraffin embedded tissue, including normal breast tissue, benign lymph nodes (LN), ductal carcinoma-in-situ (DCIS), regional LN metastases (mets), and distant mets. MassARRAY (Sequenom) genotyping was performed on native DNA to identify rare and hotspot PIK3CA mutations, as well as AKT1 (E17K), RAS, and RET mutations.ResultsConcordance of PIK3CA mutations is noted between primary BC and DCIS, except for one rare PIK3CA mutation (Q546R) not detected in DCIS (4/5). No PIK3CA mutations are detected in normal breast tissue (0/8) or benign LN (0/6). Rare and hotspot PIK3CA mutations in primary BC are detected in 87.5% (7/8) matched regional LN met and 80 % (4/5) distant mets. For the patient with the disconcordant regional LN met, the rare PIK3CA mutation (H1047L) identified in primary BC is also present in the distant met site. Notably, for the single disconcordant PIK3CA met site, a rare PIK3CA mutation (E545A) is detected in a primary tumor, regional LN met, and bone met and is absent in a second bone met, in which a KRAS (G12C) mutation has been identified. One concomitant hotspot PIK3CA (E542K)/KRAS (G12C) mutation is present in both primary BC and paired DCIS. Complete concordance of AKT1 (E17K) mutations has been identified between in DCIS, primary BC, regional LN met, and distant mets (n=4).ConclusionsWe recently defined the positive prognostic significance of PIK3CA mutations in breast cancer. PIK3CA and AKT1 (E17K) mutations are early events in breast cancer, occurring in pre-invasive tumors. Despite the protective effect of PIK3CA mutations on clinical outcome, they persist and are selected for in disease progression, as they are detected in regional LN and distant mets. Complete concordance is identified between hotspot PIK3CA mutated primary BC and matched tumors samples, suggesting that PIK3CA mutations with higher oncogenic potency are maintained in tumor progression. These findings support that targeting the PI3K pathway may assist in tailoring therapy to appropriate patient populations. We are expanding matched tissue collection from a separate patient cohort to further assess genomic and functional genomic change with disease progression.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5164.

Randomized phase II trial of nanoparticle albumin-bound paclitaxel in three dosing schedules with bevacizumab as first-line therapy for HER2-negative metastatic breast cancer (MBC)

1006

Background: Nanoparticle albumin-bound paclitaxel (nab-P) 260 mg/m2 is superior to paclitaxel 175 mg/m2 (P) every 3 weeks (Gradishar et al., J Clin Oncol. 2005). Weekly uninterrupted P is more effective than q3wk P in MBC (Seidman et al., J Clin Oncol. 2008). Bevacizumab (bev) nearly doubles response rate and time to progression (TTP) when added to P as 1st line therapy for MBC (Miller et al., N Engl J Med. 2007). Methods: This open-label, phase II study randomized patients (pts) to nab-P at 260 mg/m2 q3wk (arm A) versus 260 mg/m2 q2wk with filgrastim (arm B) versus 130 mg/m2 weekly uninterrupted, all with bev (15 mg/kg q3wk arm A, 10 mg/kg q2wk arms B and C). Pts were required to have measurable, HER-2-negative MBC and no prior chemotherapy for MBC. The primary endpoints were response rate and toxicity. Results: Accrual is complete, with 25% of pts still on study as of December 1, 2008. Of 208 pts randomized, 202 (72 arm A, 54 arm B, 76 arm C) were treated, with balanced demographics and baseline characteristics. The median age was 56 (range 29–85). 89% had visceral disease and 61% had prior neo-adjuvant or adjuvant chemotherapy. No significant differences in confirmed complete and partial response rates were noted (A: 42%, B: 42%, C: 41%). TTP was longer in arm C (9.2 months) versus both arms B (6.4 months) and A (7.7 months), overall p = 0.028. As per protocol-specified stopping rule, arm B was closed early due to unacceptable safety profile with significantly more grade ≥ 2 fatigue (B:57%, A: 39%, C:39%, p = 0.048) and bone pain (B: 19%, A: 10%, C:4%, p = 0.024). Neurotoxicity grade ≥ 2 was equivalent across all 3 arms (50%); febrile neutropenia occurred in <2% of pts in all arms. Arm C had significantly less arthralgia, myalgia, and nausea compared with arms A and B. Conclusions: Significant antitumor activity was observed in all arms. Weekly nab-P with bev (Arm C) resulted in a significantly longer TTP. Weekly nab-P with bev (Arm C) appears to have the highest therapeutic index, however sensory neuropathy is limiting, suggesting a 3 week on/1 week off schedule could be preferable and should be studied comparatively.

[Table: see text]

PIK3CA and AKT1 mutations are independent in invasive breast cancer

Abstract #1046

Background: The PI3K-AKT pathway is the most commonly altered pathway in invasive breast cancer. Somatic mutation in PIK3CA occurs in 26-30%, while AKT1 mutation was recently noted in 4-8%, other mutations occur rarely in PIK3R1 and PTEN. The prognostic implication of PIK3CA somatic mutation is inconclusive in that moderately sized retrospective studies report differing conclusions. To explain these disparate results our hypothesis is that different PIK3CA mutations impart differences in tumor biology. In an attempt to definitively identify the prognostic importance and functional attributes that specific mutations impart to breast tumor biology we are performing a broad mutation analysis on 600 archival invasive breast tumors with greater than 10 years of follow-up.&#x2028; Methods: Archival formalin-fixed paraffin embedded (FFPE) invasive breast tumors were identified from an institutional database from 1992-1996 that had known vital status and primary breast tumor size greater than 1 cm. From the confirmed invasive tumor blocks, two 10µm sections are cut for DNA extraction, punch blocks are obtained for tissue microarray (TMA) construction for immunohistochemistry and clinical demographics are collected. DNA is extracted and quantitated. PIK3CA hotspot mutations and rare PIK3CA mutations less commonly observed but thought to impart an oncogenic phenotype along with the recently identified AKT1 (E17K) mutation are assessed using the Sequenom genome multiplex array. PIK3CA hotspot mutations and AKT1(E17K) are confirmed by additional analysis on an alternate multiplex array. The first 190 cases were also assessed by Sanger sequencing for all PIK3CA coding exons.&#x2028; Results: The multiplex arrays used for the Sequenom mutation analyses had been previously validated. Thus far 400 samples have been procured and 190 cases have undergone mutation analysis. Both native DNA and DNA that had undergone whole genome amplification (WGA) were assessed to identify the most informative method for FFPE specimens. Notably, PIK3CA amplification and Sanger sequencing or WGA and mutation analysis by Sequenom multiplex array was less sensitive for identifying mutations than using unamplified native DNA with Sequenom analysis. Native DNA was informative in greater than 98% samples (3/190 uninformative) for the majority of PIK3CA mutations. All samples were informative for the most common hotspot mutation at PIK3CA (H1047R). At this report, the incidence of PIK3CA hotspot mutations (E542K, E545K, H1047R, H1047L) is 26.3% (50/190 cases), with rare PIK3CA mutations (C420R, N345K) occurring in 2.6% of cases. The more recently identified AKT1 (E17K) mutation is identified in 4.2% of cases and occurs independently of those tumors which harbor a PIK3CA mutation.&#x2028; Discussion: Mutation analysis, demographic collection and statistical analysis will be completed and updated at the meeting. The work thus far demonstrates that assessment of small amounts of archival tissue can be easily procured and undergo mutation assessment for key mutations that may be targeted therapeutically.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1046.

Distinct PIK3CA mutation profiles in estrogen receptor (ER) negative breast cancer (BC) subsets

540

Background: ER negative, progesterone receptor (PR) negative BC is clinically heterogeneous and underlying biology may be complex. We have identified two primary subtypes of ER(-)/PR(-) BC based on genome-wide molecular analysis (Doane et al., 2005, Oncogene, In Press), however the biological mechanisms underlying these molecular differences are not known. Methods: We performed genome-wide expression analysis of 99 primary BC samples and 13 BC cell lines. Total RNA was extracted and hybridized to Affymetrix HG-U133 oligonucleotide microarrays. Unsupervised and supervised analyses were used to investigate gene expression profiles. Predictive models were developed using a supervised k-nearest neighbor technique. Samples were further characterized by immunohistochemistry (IHC) for selected gene products, and HER2 status was determined by IHC and FISH. PIK3CA exons 9 and 20 were sequenced by RT-PCR amplification, direct sequencing, and restriction enzyme digest. Results: Genes differentially expressed between ER(-)/PR(-) subsets (designated class A and B) included SPDEF, ALCAM, AR, and FGFR4 (p<0.0001). Further study revealed a significant association with class A and the PIK3CA A3140G:H1047R activating mutation among ER(-)/PR(-) BC (p=0.012). HER2 status (gene amplification or 3+ IHC) was not significantly associated with this subtype (p=0.33). MDA-MB-453 corresponded to class A according to molecular profile and PIK3CA mutation status. This cell line demonstrated a proliferative response to androgen (A) in an androgen receptor (AR) dependent and ER-independent manner. In addition the A-induced transcriptional program of MDA-MB-453 significantly overlapped the molecular signature of ER(-)/PR(-) class A human BC (p<0.0001). Conclusion: Hormonal signaling through the AR may be significantly different in ER(-)/PR(-) molecular subsets. Enhanced AR signaling may be due to cooperation with growth factor signaling through PI3K. The potential molecular crosstalk between activated PI3K and the androgen signaling pathway provides therapeutic opportunities and deserves further study.

No significant financial relationships to disclose.

Vaccination of high-risk breast cancer patients with mucin-1 (MUC1) keyhole limpet hemocyanin conjugate plus QS-21

Our objective was to determine whether an immune response can be generated against MUC1 peptide and against tumor cell MUC1 after vaccination with MUC1-keyhole limpet hemocyanin (KLH) conjugate plus QS-21 in breast cancer patients. Nine patients with a history of breast cancer but without evidence of disease were treated with MUC1-KLH conjugate plus QS-21, containing 100 microg of MUC1 and 100 microg of QS-21. s.c. vaccinations were administered at weeks 1, 2, 3, 7, and 19. Peripheral blood was drawn at frequent intervals to assess antibody titers. Skin tests were placed at weeks 1, 3, 9, and 21 to determine delayed type hypersensitivity reactions. Common toxicities included a local skin reaction at the site of the vaccine, usually of 4-5 days' duration, and mild flu-like symptoms usually of 1-2 days' duration. High IgM and IgG antibody titers against synthetic MUC1 were detected. IgG antibody titers remain elevated from a minimum of 106-137 weeks after the first vaccination. Binding of IgM antibody to MCF-7 tumor cells was observed in seven patients, although there was minimal binding of IgG antibody. Two patients developed significant antibody titers post-high-dose chemotherapy and stem cell reinfusion. There was no evidence of T cell activation. This MUC1-KLH conjugate plus QS-21 was immunogenic and well tolerated in breast cancer patients. Additional trials are ongoing to determine the optimal MUC1 peptide for use in larger clinical trials. Further investigation of vaccine therapy in high-risk breast cancer is warranted.

5-year results of dose-intensive sequential adjuvant chemotherapy for women with high-risk node-positive breast cancer: A phase II study

PURPOSE

We conducted a phase II pilot study of dose-intensive adjuvant chemotherapy with doxorubicin followed sequentially by high-dose cyclophosphamide to determine the safety and feasibility of this dose-dense treatment and to estimate the disease-free and overall survival in breast cancer patients with four or more involved axillary lymph nodes.

PATIENTS AND METHODS

Seventy-three patients received adjuvant treatment with four cycles of doxorubicin 75 mg/m(2) as an intravenous bolus every 21 days, followed by three cycles of cyclophosphamide 3,000 mg/m(2) every 14 days with granulocyte colony-stimulating factor support.

RESULTS

Seventy-one patients were assessable, and all but two completed all planned chemotherapy. There was no treatment-related mortality. The most common toxicity was neutropenic fever, which occurred in 39% of patients. Median disease-free survival is 66 months (95% confidence interval, 34 to 98 months), and median overall survival has not yet been reached. At 5 years of follow-up, the disease-free survival is 51.7%, and overall survival is 60.0%. There is no long-term treatment-related toxicity, and no cases of acute myelogenous leukemia or myelodysplastic syndrome have been observed.

CONCLUSION

Our pilot study of doxorubicin followed by cyclophosphamide demonstrates the safety and feasibility of the sequential dose-dense plan. Long-term follow-up, although noncomparative, is promising. However, this regimen is associated with a higher incidence of toxicity (and also higher costs) than the standard dose and schedule of doxorubicin and cyclophosphamide, and therefore it should not be used as conventional therapy in the absence of demonstrated improvement of outcome. Randomized trials testing the dose-dense approach have been completed but not yet reported. Because the sequential plan can decrease overlapping toxicities, it is an appropriate platform for the addition of newer active agents, such as taxanes or monoclonal antibodies.

Sequential dose-dense doxorubicin, paclitaxel, and cyclophosphamide for resectable high-risk breast cancer: feasibility and efficacy

PURPOSE

Dose-dense chemotherapy is predicted to be a superior treatment plan. Therefore, we studied dose-dense doxorubicin, paclitaxel, and cyclophosphamide (A-->T-->C) as adjuvant therapy.

METHODS

Patients with resected breast cancer involving four or more ipsilateral axillary lymph nodes were treated with nine cycles of chemotherapy, using 14-day intertreatment intervals. Doses were as follows: doxorubicin 90 mg/m2 x 3, then paclitaxel 250 mg/m2/24 hours x 3, and then cyclophosphamide 3.0 g/m2 x 3; all doses were given with subcutaneous injections of 5 microg/kg granulocyte colony-stimulating factor on days 3 through 10. Amenorrheic patients with hormone receptor-positive tumors received tamoxifen 20 mg/day for 5 years. Patients treated with breast conservation, those with 10 or more positive nodes, and those with tumors larger than 5 cm received radiotherapy.

RESULTS

Between March 1993 and June 1994, we enrolled 42 patients. The median age was 46 years (range, 29 to 63 years), the median number of positive lymph nodes was eight (range, four to 25), and the median tumor size was 3.0 cm (range, 0 to 11.0 cm). The median intertreatment interval was 14 days (range, 13 to 36 days), and the median delivered dose-intensity exceeded 92% of the planned dose-intensity for all three drugs. Hospital admission was required for 29 patients (69%), and 28 patients (67%) required blood product transfusion. No treatment-related deaths or cardiac toxicities occurred. Doxorubicin was dose-reduced in four patients (10%) and paclitaxel was reduced in eight (20%). At a median follow-up from surgery of 48 months (range, 3 to 57 months), nine patients (19%) had relapsed, the actuarial disease-free survival rate was 78% (95% confidence interval, 66% to 92%), and four patients (10%) had died of metastatic disease.

CONCLUSION

Dose-dense sequential adjuvant chemotherapy with doxorubicin, paclitaxel, and cyclophosphamide (A-->T-->C) is feasible and promising. Several ongoing phase III trials are evaluating this approach.

Phase II study of semisynthetic paclitaxel in metastatic breast cancer

The aim of this phase II study was to characterise the efficacy and toxicity of semisynthetic paclitaxel in patients with metastatic breast cancer. Eligible patients had measurable disease and had been treated with one prior chemotherapy regimen either as adjuvant or for metastatic disease. Semisynthetic paclitaxel was given at a dose of 175 mg/m2 over 3 h every 21 days with dexamethasone, cimetidine and diphenhydramine premedications. 31 patients were entered. All were evaluable for toxicity. 30 patients were evaluable for response because 1 patient was lost to follow-up after receiving one cycle. One patient achieved a complete response and 10 patients achieved partial responses for an overall response rate (CR + PR) of 37% (95% confidence interval 20-56%). 17 patients (55%) experienced at least one episode of grade 3 or 4 neutropenia. There were two episodes of febrile neutropenia complicating 155 cycles of therapy. One of these resulted in a treatment-related death in a patient with pulmonary metastasis. 3 patients required dose reductions for grade 3 sensory neuropathy. Our study shows that the antitumour activity and toxic effects of semisynthetic paclitaxel appear to be identical to the naturally occurring product.

Home use of a functional electrical stimulation system for standing and mobility in adolescents with spinal cord injury

OBJECTIVE

Functional electrical stimulation (FES) is a technology that may allow some patients with spinal cord injury (SCI) to integrate standing and upright mobility with wheelchair mobility. The purpose of this study was to document the patterns of home and community use of a FES system for standing and mobility.

DESIGN

A telephone questionnaire was administered every 1 to 4 weeks for a minimum of 1 year. An interview was given at the end of the study to probe the motivators and barriers to home use.

SETTING

Training for use of the FES system was performed in an inpatient pediatric rehabilitation setting. Data collection began after the subjects were discharged to home.

PARTICIPANTS

Five adolescents with complete, thoracic-level SCI.

INTERVENTION

Subjects participated in a program of FES exercise followed by training in basic mobility skills such as standing transfers, maneuvering, level ambulation, one-handed and reaching activities, and stair ascent/descent.

MAIN OUTCOME MEASURE

The frequency with which the FES system was used at home and the activities for which it was utilized were documented. Motivators and barriers to FES home use were examined.

RESULTS

Subjects donned the FES system on the average once every 3 to 4 days. Between 51% and 84% of the times donned, the system was used for exercise. The remaining times it was used for standing activities, most commonly reaching, one-handed tasks, and standing for exercise. "Motivators" included being able to do things that would otherwise be difficult, perceiving a healthful benefit or a sense of well-being from standing and exercise, and feeling an obligation to stand as a participant in a research study. "Barriers" to FES use included not finding time to use the system, having difficulty seeing opportunities to stand, and being reluctant to wear the FES system all day.

Characterization of the bone mineral density of children with spinal cord injury

The purpose of this study was to compare the bone mineral density in children with spinal cord injury (SCI) with age- and sex-matched controls in three anatomic areas of the proximal hip. In addition, post hoc analysis looked for differences in bone density between sub-groups considering several factors associated with spinal cord injury: the presence or absence of spasticity, the level of injury and the presence or absence of pathologic fractures. Fifty-one pediatric patients with spinal cord injury between the ages of 3 and 20 underwent bone density measurements using dual photon absorptiometry. Before pooling the data across age groups, all measurements were normalized to age- and sex-matched controls because of increasing bone density with growth and higher bone density in males. The results revealed lower bone densities in subjects with SCI as compared with their non-disabled peers, ranging from 56 percent to 65 percent of normal across the three anatomic regions. On the average, subjects who had a previous history of fractures had significantly lower bone density measurements than those without fractures. At the intertrochanteric region, a 10.6 percent difference was noted between subjects with tetraplegia versus those with paraplegia. At the femoral neck and Ward's Triangle, an 8.5 percent difference was noted between subjects with and without spasticity. No conclusions could be drawn from the analyses at the other sites. Together these results begin to characterize bone density levels of the pediatric SCI population.

Sequential adjuvant therapy: the Memorial Sloan-Kettering Cancer Center experience

Adjuvant chemotherapy has a real but modest impact on the disease-free and overall survival of patients with breast cancer. Recent attempts to improve its effectiveness have focused on dose intensity and new agents. Sequential therapy maximized dose intensity while limiting overlapping toxicity. Sequential therapy using doxorubicin followed by cyclophosphamide/methotrexate/5-fluorouracil (CMF) has been found superior in patients with high-risk resectable breast cancer. The novel chemotherapy agent paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) is now known to be highly active in advanced breast cancer and appears to be clinically non-cross-resistant with doxorubicin. Therefore, this drug is being studied as a component of the next generation of adjuvant chemotherapy regimens. The most appropriate way to incorporate paclitaxel has not yet been defined, but its concurrent administration with other agents has, in some cases, been troublesome. Based on the demonstrated advantage of the sequential plan for doxorubicin and CMF, we conducted a series of pilot trials testing sequential high-dose therapy. Initially, we studied multiple cycles of doxorubicin followed by cyclophosphamide; we later added paclitaxel to this regimen. These phase II studies demonstrate the feasibility of sequential therapy with doxorubicin, paclitaxel, and cyclophosphamide, and early disease-free survival results are promising. Cooperative group projects are under way or planned to further define the activity of these regimens.

Bipolar latissimus dorsi transposition and functional neuromuscular stimulation to restore elbow flexion in an individual with C4 quadriplegia and C5 denervation

A bipolar latissimus dorsi transposition was performed on a 17-year-old male patient with a C4 spinal cord injury and complete peripheral denervation at C5. Electrical stimulation of the paralyzed but excitable latissimus dorsi provided elbow flexion that could not be achieved with the paralyzed and denervated elbow flexors. The muscle was attached from the coracoid to the ulna allowing the elbow to be flexed with the forearm and wrist maintained in the neutral position. Following a 6-week immobilization period, the transposed muscle was exercised daily with intramuscular stimulation to increase both strength and endurance. By the fourth month after surgery, the subject could control elbow flexion proportionally with contralateral shoulder elevation using a shoulder position transducer. Functionally, the subject was able to use the neuroprosthetic system to bring his hand to his mouth and feed himself with the aid of a universal cuff and a support to stabilize the shoulder.