A combinatorial biomarker predicts pathologic complete response to neoadjuvant lapatinib and trastuzumab without chemotherapy in patients with HER2+ breast cancer

BACKGROUND

HER2-positive (+) breast cancers, defined by HER2 overexpression and/or amplification, are often addicted to HER2 to maintain their malignant phenotype. Yet, some HER2+ tumors do not benefit from anti-HER2 therapy. We hypothesize that HER2 amplification levels and PI3K pathway activation are key determinants of response to HER2-targeted treatments without chemotherapy.

PATIENTS AND METHODS

Baseline HER2+ tumors from patients treated with neoadjuvant lapatinib plus trastuzumab [with endocrine therapy for estrogen receptor (ER)+ tumors] in TBCRC006 (NCT00548184) were evaluated in a central laboratory for HER2 amplification by fluorescence in situ hybridization (FISH) (n = 56). HER2 copy number (CN) and FISH ratios, and PI3K pathway status, defined by PIK3CA mutations or PTEN levels by immunohistochemistry were available for 41 tumors. Results were correlated with pathologic complete response (pCR; no residual invasive tumor in breast).

RESULTS

Thirteen of the 56 patients (23%) achieved pCR. None of the 11 patients with HER2 ratio <4 and/or CN <10 achieved pCR, whereas 13/45 patients (29%) with HER2 ratio ≥4 and/or CN ≥10 attained pCR (P = 0.0513). Of the 18 patients with tumors expressing high PTEN or wild-type (WT) PIK3CA (intact PI3K pathway), 7 (39%) achieved pCR, compared with 1/23 (4%) with PI3K pathway alterations (P = 0.0133). Seven of the 16 patients (44%) with HER2 ratio ≥4 and intact PI3K pathway achieved pCR, whereas only 1/25 (4%) patients not meeting these criteria achieved pCR (P = 0.0031).

CONCLUSIONS

Our findings suggest that there is a clinical subtype in breast cancer with high HER2 amplification and intact PI3K pathway that is especially sensitive to HER2-targeted therapies without chemotherapy. A combination of HER2 FISH ratio and PI3K pathway status warrants validation to identify patients who may be treated with HER2-targeted therapy without chemotherapy.

Abstract P4-15-05: Biomarkers of response to neoadjuvant endocrine therapy with anastrozole (Ana) alone or in combination with fulvestrant (Ful) in ER-positive (ER+) HER2-negative (HER2-) breast cancer (PACT01 trial)

Background: In recent years, several clinical trials showed that fulvestrant (Ful), alone or in combination with an aromatase inhibitor (AI), is more effective than an AI alone. PACT01 is a randomized neoadjuvant trial of Anastrazole (Ana) alone or in combination with Ful in ER+/HER2- breast cancer.

Methods: Patients with newly diagnosed ER+/HER2- breast cancers, 2 cm or larger in size, were randomized to 16 weeks of Ana (1 mg orally every day) alone or in combination with Ful (500mg IM days 1, 15, 29, and every 28 days thereafter) for 16 weeks. Patients then proceeded to surgery. Tumor tissue was collected at baseline, day 28 (D28), and at the time of surgery. Primary endpoint was the reduction of Ki67 in tumor tissue between baseline and D28. Baseline and D28 samples were stained for ER, PR, HER2, and Ki67. ER and PR were scored for intensity and percentage (H-score), HER2 was scored for intensity of membrane staining; and Ki67 was scored as percentage. Data were summarized descriptively. Changes in biomarkers from baseline to D28 were calculated and compared by Wilcoxon signed rank test.

Results: PACT01 trial enrolled 72 patients. Three of them did not start treatment. Baseline samples were collected from the remaining 69 patients, and D28 samples from 60 patients (5 refused, 2 withdrew, 1 lost to follow up, 1 unknown). Samples from 18 patients had no tumor (5 at baseline, 9 at D28, 4 at both). Of the 42 patients with paired samples, 20 received Ana and 22 received Ana+Ful. All cases except one were centrally confirmed to be ER+, and all were HER2-. Table 1 summarizes median expression of Ki67, ER, and PR. Both treatment regimens led to a significant reduction in Ki67 between baseline and D28. However, Ana+Ful did not reduce Ki67 more effectively than Ana alone. Ki67 was reduced to &lt;10% in 60% of the Ana arm and 68% of the Ana+Ful, which was not statistically significant.PR was similarly reduced in both treatment arms. ER was significantly reduced at D28 in the Ana+Ful arm (p=0.0004) but not in the Ana alone arm. Safety profile of both treatment arms was consistent with package insert and published studies.

Median expression of Ki67, ER and PR in Anastrazole and Anastrazole + Fulvestrant Arms at Baseline and Day 28ARMTimepointNKi67 (%)ER H-scorePR H-scoreAnaBaseline2024.8182.5100.3 Day 28205.6*170.025.0Ana + FluBaseline2225.6198.120.5 Day 28225.1*117.50.0* p=0.0004. Other comparisons were not stastistically significant

Conclusions:In this small neoadjuvant trial, the addition of Ful to Ana did not increase Ki67 suppression at D28. This may be due to untreated primary tumors being exquisitely sensitive to Ana and that fulvestrant may not add to it. It is also possible that the effect of Ful may be noted later in the course of treatment. Further biomarker data on tissue collected at the end of treatment will be presented at the meeting.

Citation Format: Dhamne S, Nagi C, Wang T, Pavlick AC, Reusser B, Schiff R, Julie N, Niravath P, Silberfein EJ, Sedgwick EL, Sepulveda KA, Gutierrez C, Hilsenbeck SG, Chang JC, Osborne CK, Rimawi MF. Biomarkers of response to neoadjuvant endocrine therapy with anastrozole (Ana) alone or in combination with fulvestrant (Ful) in ER-positive (ER+) HER2-negative (HER2-) breast cancer (PACT01 trial) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-15-05.

Abstract PD1-2: PIK3CA mutations and/or low PTEN predict resistance to combined anti-HER2 therapy with lapatinib and trastuzumab and without chemotherapy in TBCRC006, a neoadjuvant trial of HER2-positive breast cancer patients

We have recently reported that in patients with HER2-positive breast cancer, neoadjuvant targeted therapy with lapatinib and trastuzumab to more completely block the HER receptor layer, combined with endocrine therapy (in ER-positive tumors) and without chemotherapy led to a substantial 27% pathologic complete response (pCR) rate in the breast. Activation of downstream signaling pathways may lead to resistance to therapies targeting the HER pathway receptors. Aberrant activation of the PI3K pathway via decreased levels of PTEN and/or the presence of activating PIK3CA mutations has been implicated in resistance to targeted anti-HER2 therapy, but results of clinical trials are all confounded by the co-administration of chemotherapy and are inconsistent. We sought to clarify the role of these variables in predicting pCR, a surrogate for long-term outcome, in patients treated with potent targeted therapy alone in a prospective Phase II neoadjuvant trial in patients with HER2-positive breast cancer.

Patients with large tumors (median 6 cm) were given 12 weeks of lapatinib plus trastuzumab followed by surgery (Rimawi et al. JCO, 2013). Serial tissue biopsies were obtained from study participants. For this study, we focused on baseline pre-treatment characteristics. PTEN protein levels were measured by IHC and scored using the H-score. PIK3CA mutations were identified on extracted DNA using multiplex PCR with targeted next generation sequencing (the Ion Torrent 50-gene cancer mutation panel).

Of 64 evaluable patients, tissue was available on 59 for PTEN IHC, and sufficient DNA was available on 33 for the mutation panel. PTEN median H-score was 100 (range 0-300). PTEN status when dichotomized by the median was correlated with pCR (32% in high PTEN vs. 9% in low PTEN, p = 0.04). Activating PIK3CA mutations were identified in 12 out of 33 tumors (36%; 3 mutations in the helical and 9 in the catalytic domain) and were independent of ER status. None of the patients whose tumors harbored a PIK3CA mutation achieved pCR (p = 0.06). There was no association between PTEN status and PIK3CA mutation suggesting they are independent variables (p = 0.44). When PIK3CA mutations were considered together with PTEN status, there were 31 cases with data on both. The overall pCR rate in this cohort was 16% (lower than pCR rate observed in the overall trial). However, 0/17 cases (0%) with a mutation and/or PTEN low expression (&lt;100 H score) had a pCR compared to 5/14 cases (36%) with PI3KCA wild type and high PTEN levels (p = 0.01).

We conclude that PI3K pathway activation downstream of HER2 as a result of either low PTEN or activating PIK3CA mutation results in resistance to the combination of lapatinib and trastuzumab. This is the first report on patient tissue samples from a neoadjuvant trial using the combination of lapatinib and trastuzumab without chemotherapy. If validated in a larger cohort, our findings suggest that patients with HER2 positive tumors and who also harbor aberrant downstream PI3K pathway activation may benefit from the addition of PI3K/Akt/mTOR inhibitors to potent HER2 blockade.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD1-2.

P5-21-01: A Renewable Tissue Resource of Phenotypically Stable Human Breast Cancer Xenografts for Preclinical Studies

Introduction Translational breast cancer research is hampered severely by difficulties in obtaining and studying primary human breast tissue, and by the lack of in vivo preclinical models that accurately reflect patient tumor biology. These limitations are due, in part, to the fact that traditional immunocompromised mouse models are not generally permissive for growth. We sought to circumvent some of these limitations by transplanting and growing human mammary tumors in the mammary fat pad of SCID/Beige immunocompromised mice in the absence of exogenous human fibroblasts.

Aims and Methods To establish a set of stable human breast cancer xenografts for preclinical studies. Human breast cancer biopsies were received, minced into small fragments and then transplanted directly into “cleared” fat pads of recipient SCID/Beige immunocompromised mice. Transplanted fat pads were checked weekly. After initial tumor was palpated and harvested, tumor fragments were transplanted into new SCID/Beige hosts for subsequent transplant generations. Serial immunohistochemical evaluations were performed to confirm human origin and biomarker status. Analytical flow cytometry for evaluating expression of proposed “cancer stem cell” markers, and gene and protein expression analysis were carried out on all stable lines.

Results and Conclusions Xenograft lines were established directly from breast cancer patient samples, without intervening culture in vitro, using the epithelium-free mammary fat pad as the transplantation site. Of the conditions tested, xenograft take rate was highest in the presence of a low-dose estradiol pellet without exogenous human fibroblasts. Thirty six stably transplantable xenograft lines representing 27 patients were established, using pre-treatment, mid-treatment, and/or post-treatment samples. Most patients yielding xenografts were “triple-negative” (ER-PR-HER2−) (n=21), we were able to establish lines from three ER-PR-HER2+ patients, one ER+PR+HER2−, one ER+PR-HER2−and one “triple-positive” (ER+PR+HER2+) patients. Serially passaged xenografts show phenotypic consistency with the tumor of origin at the histopathology level, and remarkable stability across multiple transplant generations at both the genomic, transcriptomic, and proteomic levels. Of 27 lines evaluated fully, thirteen xenografts showed metastasis to the mouse lung. These models thus serve as a renewable, quality-controlled tissue resource, and should prove useful for preclinical evaluation of experimental therapeutics.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-21-01.

Phase I/II study of arginine deiminase (ADI-PEG 20) in patients with advanced malignant melanoma (MM)

9030

Background: ADI-PEG 20 is an enzyme that degrades arginine, a crucial amino acid central to metabolism and biosynthesis of growth and development of normal and neoplastic cells. Melanoma is auxotrophic for arginine because it lacks argininosuccinate synthetase (ASS), a key enzyme required for synthesis of arginine from citrulline via the urea cycle. This study evaluates the safety and clinical efficacy of ADI-PEG 20 in patients with MM. Methods: Patients with histologically confirmed stage III (unresectable)/ IV cutaneous, uveal or mucosal MM were treated with 40, 80 or 160 IU/m2 ADI-PEG 20 i.m. weekly for 9 weeks in a phase I setting. In a phase II component, 16–25 pts receiving 160 IU/m2 will be evaluated for tumor response (TR) by RECIST. Secondary endpoints for all patients included metabolic response by 18FDG-PET, pharmacodynamics (PD), immunogenicity and ASS tumor expression by immunohistochemistry. Results: As of Nov. 2008, 24 pts were enrolled (40 IU/m2, n=6, 80 IU/m2, n=6, 160 IU/m2, n=12): 14 males, 10 females. Median age: 66 yrs (range 29- 83 yrs). Toxicity consisted primarily of Grade 1/2 adverse events (AE) (injection site pain, myalgia, arthralgia, fatigue, flushing, rash/itch, nausea, diarrhea, hyperuricemia, taste alteration). One dose limiting toxicity (DLT) of G3 arthralgia was observed at 80 IU/m2. Two DLTs (G3 seizure and G3 lymphedema) were reported, at 160 IU/m2. No grade 4 or 5 AEs were observed. Of 22 patients evaluable for TR, 8 had stable disease (SD) with 2 of these durable for ≥ 6 months. Notably, 3 SD were uveal melanoma. 14 patients had progressive disease. PD analysis showed plasma arginine depletion during study weeks 1–6 regardless of dose. Immunohistochemical ASS expression analysis in tumor tissue: negative= 13 pts, < 5% cells positive= 5 pts. Conclusions: ADI-PEG 20 as a single agent is well tolerated in advanced MM leading to consistent arginine depletion. The extent of clinical activity has yet to be shown. Combination therapy of ADI-PEG20 with other treatments such as pro-apoptotic reagents during the first 6 weeks of ADI-PEG 20 treatment while arginine is depleted could lead to synergistic anti-cancer activity.

No significant financial relationships to disclose.

A phase I and pharmacological study of MK-1775, a Wee1 tyrosine kinase inhibitor, in both monotherapy and in combination with gemcitabine, cisplatin, or carboplatin in patients with advanced solid tumors

3510

Background: MK-1775 is an inhibitor of Wee1, a kinase that phosphorylates CDC2 to inactivate the CDC2/cyclin B complex (regulating the G2 checkpoint). Since most human cancers harbor p53-dependent G1 checkpoint abnormalities, they are dependent on the G2 checkpoint. G2 checkpoint abrogation may therefore sensitize p53 deficient tumor cells to anti-cancer agents. Methods: This study is evaluating the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of MK-1775 administered as both monotherapy (MT) and combination therapy (CT) with gemcitabine (G), cisplatin (P), or carboplatin (C). PART 1 consists of a single dose of MK-1775 followed by 14 days observation. If well tolerated, the same pt continues on to one of three treatment arms in PART 2: a single lower dose of MK-1775 in combination with: 1) 1000 mg/m2 G, 2) 75 mg/m2 P or 3) C AUC 5. Maximum Tolerated Doses (MTDs) will be established for MK-1775 as both monotherapy and in combination. PD biomarkers include IHC analysis for pCDC2/CDC2 in plucked hair and skin biopsies, peripheral blood, and tumor biopsies. Wee1 gene expression signature is measured in plucked hair and tumor biopsies by qPCR. Results: To date, 37 pts (median age 61; up to 4 prior therapies) have been treated with MK-1775. 4 pts experienced DLT. One pt on G + 200mg MK-1775 had gr3 leucopenia and neutropenia; one pt on P + 200mg MK-1775 had gr3, fatigue, diarrhea and hypokalemia and another pt gr2 nausea/vomiting > 48hrs requiring hospitalization. One pt on C + 325mg MK-1775 was hospitalized for gr3 bilirubin. Linear PK was demonstrated at 100, 200, 325, 650 and 1300 mg MK-1775. Terminal T½ of MK-1775 was 7.6–12.2 hrs and Tmax was 1.0–6.0 hrs. Preliminary MTDs of MK-1775 in combination with G, C and P were 200, 325 and 200mg, respectively. Significant changes in Wee1 signature gene expression were observed in plucked hair. Of 28 evaluable pts, >50% regression of axillary lymphadenopathy was seen in 1 pt with melanoma on the P arm, and stable disease in 14 other pts (median duration). Conclusions: MK-1775 is a first in class Wee1 inhibitor that is well tolerated and shows promising anti-tumor activity in previously treated pts.

[Table: see text]

Association between HU177 serum level and prognosis in patients with primary melanoma

9044

Background: Cleavage of type IV collagen during extracellular matrix (ECM) remodeling leads to exposure of cryptic regulatory sites within the ECM shown to be involved in tumor angiogenesis. Increased levels of a soluble form of the cryptic epitope HU177 in sera of melanoma patients have been shown to be associated with greater tumor thickness and nodular histological subtype. In this study, we investigate the association between HU177 serum levels and melanoma patients' clinical outcomes. Methods: Sera from 209 patients with primary melanoma prospectively enrolled in the Interdisciplinary Melanoma Cooperative Group at the New York University Langone Medical Center (85 females, 124 males, mean age=58, mean thickness=2.09 mm, Stage I n=140, Stage II n=40, Stage III n=29) were analyzed for HU177 level. HU177 serum levels at the time of diagnosis were then correlated with disease-free survival (DFS) and overall survival (OS). Results: Median follow-up time for survivors was 54.9 months (range 2–81 months). Thirty-eight of the 209 (18%) patients developed recurrences, and 34 of the 209 (16%) patients died during follow-up. HU177 sera levels ranged from 0–139.9 ng/ml (mean=6.2 ng/ml; median=3.7 ng/ml). Because the distribution of HU177 levels was positively skewed, we analyzed the data using the median in addition to the mean. HU177 level > 3.7 ng/ml (the median) was associated with a higher rate of melanoma recurrence (p=0.04) and increasing mortality (p=0.01) in a Kaplan Meier analysis. HU177 remained an independent prognostic factor for DFS and OS when controlling for tumor thickness and histological subtype in multivariate Cox proportional hazards regression models. In the DFS hazard model controlling for tumor thickness and histology, the hazard ratio for HU177 >3.7 ng/ml (the median) was 2.01 (95% CI= 1.002, 4.04; p=0.049). In the OS hazard model controlling for tumor thickness and histology, the hazard ratio for HU177 >3.7 ng/ml (the median) was 2.23 (95% CI=1.06, 4.70; p=0.03). Conclusions: Increased serum level of HU177 identifies a subset of primary melanoma patients with worse prognosis and suggests that anti-angiogenic therapy in the adjuvant setting may be a rational approach.

[Table: see text]

Prognostic factors for survival in patients with stage (stg) IV malignant melanoma (MM)

9072

Background: Prognosis for survival in MM is not uniform with some pts being long-term survivors. Identifying this subset of pts may have implications on surveillance and treatment (tx). Unfortunately, prognostic data available for MM and the utility of AJCC staging in predicting survival is limited. We analyzed prospectively collected data from the NYUCI Interdisciplinary Melanoma Cooperative Group program (IMCG) to identify clinicopathological variables predictive of MM survival. Methods: We identified 185 pts enrolled in the IMCG with MM diagnosed and treated at NYUCI. Demographic, clinical, and tx-related factors were included in the analysis. Kaplan-Meier (KM) survival analysis was used to identify univariate predictors of post-stage IV survival and their independent effect was assessed in a multivariate Cox proportional hazards regression model. Results: Median age at diagnosis (dx) of metastatic MM was 64 years (22–92). Median overall survival: 13.8 months(m) (128 deaths and a median follow up of 18.6 m (4–141) for survivors). Factors identified on univariate analysis at p<0.20 were evaluated in the multivariate model ( table ). Co-morbidities, site and histology of primary melanoma, initial staging, prior loco-regional recurrences, and adjuvant tx of primary melanoma were not associated with MM survival. Univariate analysis also showed significant survival advantage (p value 0.0011) for patients with AJCC stages M1a and M1b (21.6 m and 17.2 m respectively) over those with AJCC stage M1c (9 m). Conclusions: This cohort study of MM identified female gender, nl serum LDH, nl albumin, and solitary organ involvement as independent survival predictors. Patients who received systemic therapy± local measures had survival benefit over those that had surgery and/or radiation alone suggesting a role for systemic treatment in MM. Patients with personal history of another malignancy (n=37) showed a trend towards improved survival. This novel observation needs to be validated and studied further.

[Table: see text]

No significant financial relationships to disclose.

Survival of advanced melanoma patients with normal LDH treated with oblimersen, temozolomide, and nab-paclitaxel

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Background: Oblimersen (OBL), temozolomide (TMZ), and abraxane (ABX) act synergistically in preclinical studies with melanoma cell lines. Bcl-2 antisense therapy in combination with dacarbazine was encouraging in advanced melanoma patients(pts) with normal LDH. Methods: Chemotherapy-naïve advanced melanoma pts (ECOG PS ≤ 2, baseline LDH ≤1.1 × ULN, measurable disease per RECIST) were enrolled on a phase I/II protocol. The treatment regimen consisted of 56-day cycles of OBL (7 mg/kg/d continuous IV infusion, d 1–7 and 22–28), TMZ (75 mg/m2/d, d 1–42), and ABX (175 mg/m2 in Cohort 1, 260 mg/m2 in Cohort 2, d 7 and 28). Immunohistochemical (IHC) staining for Bcl-2, Bcl-XL, BAK and caspase 3 was performed in pre- and post-therapy tumor samples. Serum shed collagen cryptic epitope levels were monitored. Results: 18 pts were treated (Cohort 1 = 14 pts [1–6 cycles];Cohort 2 = 4 pts [2–3 cycles]). Median age was 58 years (range: 34–78). Disease sites included liver (6), other visceral sites (10), skin, subcutaneous tissue, and lymph nodes (2). The overall survival (OS) was 14.7 months and showed a trend towards superiority when compared to both arms of the prior oblimersen trial (DTIC, OS 9.7 months, p = 0.078 and DTIC-OBL, OS 11.4 months, p = 0.31) in pts with the same LDH cut-off (Bedikian et al. JCO. 2006). 50% of pts survived > 1 year. One CR lasted 25+ mo, five PR (>50% tumor reduction) lasted > 2 cycles, and 7 SD lasted > 3 cycles. Five PD after 1 cycle were seen. One ocular melanoma pt survived 15 mo despite PD. Shed cryptic epitopes correlated with clinical response versus disease progression. Alteration of the tumor biology based on phenotypic changes in Bcl-2, Bcl-xL, BAK and caspase 3 correlated with response to treatment. Conclusions: Our data suggest that the combination of OBL, TMZ, and ABX is synergistic in advanced melanoma pts with normal LDH, possibly translating into improved OS compared to prior regimens with dacarbazine ± OBL. Biomarker studies support the rationale that Bcl-2 antisense therapy specifically impacts apoptotic signaling pathways in melanoma cells from metastatic tumor. The survival data in the limited number of pts enrolled in cohort 1 and 2 of this trial are encouraging; further exploration with this combination is underway using 1-hour infusions of OBL.

No significant financial relationships to disclose.

Comparison of the immunogenicity of Montanide ISA 51 adjuvant and cytokine-matured dendritic cells in a randomized controlled clinical trial of melanoma vaccines

3002

Background: Dendritic cell (DC) vaccines have been widely used in clinical trials to treat cancer. However, no study has compared the immunogenicity of the most commonly used DC type (cytokine-matured, monocyte-derived DCs) to more traditional vaccine adjuvants. We performed a randomized controlled trial comparing the immunogenicity of cytokine-matured DCs loaded with 6 HLA-A2-restricted peptide antigens and a foreign protein, KLH, to a vaccine containing the same antigens emulsified in the mineral oil adjuvant Montanide ISA 51 VG. Methods: 51 HLA-A2+ patients with resected stage IIb-IIIc melanoma were randomized to receive DCs (25 patients) or Montanide (26 patients). DCs were differentiated from autologous blood monocytes with IL-4 and GM-CSF, then matured with IL- 1β, IL-6, TNFα and PGE2. 18 million DCs were given i.d. every 4 weeks x 4, and immune responses analyzed (MHC multimers, T cell proliferation, cytokine secretion, antibodies). A 3-fold increase over baseline was considered a response. Results: Both vaccines were well tolerated. Immunogenicity was significantly greater with Montanide, as demonstrated by response rates to Flu, Melan-A and NY-ESO-1 peptides by IFNγ ELISPOT. Similar results were obtained by MHC multimer staining, with higher response rates seen using pre-sensitized assays. T cell proliferation to KLH was seen in both arms (90% DC, 100% Montanide), but the magnitude of response was significantly higher for Montanide (36-fold vs. 14-fold increase over baseline, p=0.002, Wilcoxon). KLH-specific CD4+ T cells that produced IFNγ, TNFα and IL-2 were seen only with Montanide, and all Montanide patients, but only 5% of DC patients, developed antibodies to KLH (p<0.001, Fisher's). Conclusions: A water-in-oil vaccine adjuvant, Montanide ISA 51, was significantly more immunogenic than DCs. Future studies of new DC vaccines should compare DCs to standard adjuvants to determine if their added difficulty and expense are truly warranted.

[Table: see text]

[Table: see text]

A phase II study of imatinib mesylate (IM) for patients with advanced melanoma harboring somatic alterations of KIT

9001

Background: Three prior phase II studies of Imatinib mesylate (IM) in 62 pts with advanced melanoma reported only 1 response in a pt with acral melanoma. A proportion of melanomas arising from acral, mucosal, and chronic sun damaged (CSD) sites are characterized by KIT mutations (mut) or amplifications (amp) and we hypothesized that this subset of tumors would be sensitive to IM. We thus designed this phase II study of IM restricted to pts with melanoma harboring such alterations in KIT. Methods: Pts with unresectable melanoma arising from acral, mucosal, and CSD sites whose tumor harbored a 4q12 amp by FISH or mut in KIT and who had measureable disease by RECIST were eligible. Pts received IM 400 mg BID continually. Response was assessed every cycle (6 wks). A Simon 2-stage design was employed where initially 16 pts would be treated; if ≥ 2 responses were observed, a total of 25 pts would be enrolled. If ≥5 responses were seen in 25 pts, the study was to be considered positive. Results: Of 81 pt tumors screened, 17 (21%) had a KITmut or amp: 5/22 (23%) acral, 12/45 (27%) mucosal, 0/13 (0%) CSD, 0/1 (0%) unknown primary. 12 (15%) had a mut only; 4 (5%) had an amplification only; 1 (2%) had both. Thus far, 7 have been treated, with 5 currently evaluable for response. Median age: 64 yrs (range, 61–86); 2 male/5 female; median KPS: 90 (range, 80- 90); median # of prior therapies: 1 (range, 0–4). 3 pts (43%) achieved a PR (18 wks - exon 13 mut; 21 wks, ongoing - exon 11 mut; 18 wks, ongoing - exon 11 mut & amp); 2 pts (28%) achieved SD (12 wks - exon 11 mut; 11 wks - amp). 3 pts required a dose reduction to 400 mg QD for rash, GI toxicity and fatigue. 1 pt required a second dose reduction to 300 mg QD for visual changes. Conclusions: In this pt population, 21% of tumors are characterized by mut or amp of KIT. The 3 responses observed have allowed expansion to the second stage of enrollment which is currently on-going. While IM has limited activity in a non-selected melanoma pt population, a substantial proportion of melanomas harboring KIT mut or amp appear to respond. It may be possible to identify appropriate pts prospectively for treatment with IM. (Supported by R01FD003445–01, ASCO YIA, N01CM62206, and the Live4Life Foundation.)

No significant financial relationships to disclose.

LDH is a prognostic factor in stage IV melanoma patients (pts) but is a predictive factor only for bcl2 antisense treatment efficacy: Re-analysis of GM301 and EORTC18951 randomized trials

8552

Background: Two large studies with identical eligibility criteria and using serum LDH as stratification for randomization were re-analyzed in order to 1) confirm the prognostic importance of LDH in advanced melanoma; 2) to assess whether an interaction between LDH and treatment efficacy exists. Methodology: Oblimersen (OBL) trial GM301 randomized 771 pts between DTIC vs. DTIC+OBL, whereas EORTC trial 18951 randomized 365 pts between biochemotherapy vs biochemotherapy+IL2 (JCO, 2004). LDH was divided into 5 groups: 5 UNL. Cox model was used to asses the prognostic importance of LDH, treatment difference and LDH-treatment interaction regarding the main endpoint, overall survival (OS). Results: In each study LDH appeared to be of strong and incremental prognostic importance (p<0.0001): the higher the LDH the shorter the OS. Median OS in pts with LDH<0.8 UNL was ±1 yr vs. 5 UNL. In both trials, pts with LDH 0.8–1.1 UNL had already a shorter median OS (± 9 months) as compared to the <0.8 group. In each study, overall, treatment differences were not significant. However, an interaction between LDH and treatment difference was observed in GM301 (p=0.01), but not in 18951 (p=0.51). In GM301, the largest benefit in favor of OBL was confined to the LDH <0.8 UNL subgroup (see table ), whereas in EORTC18951 the trend for an IL2 advantage was spread over several LDH groups. The observation was consistent also for response and PFS, and was not related to known confounding variables including metastatic disease site and PS. Conclusion: LDH is a biomarker with remarkable prognostic value for OS in advanced melanoma, and our analysis provides evidence for its prognostic value already below the UNL. Furthermore, OBL only had an effect in pts with low pretreatment LDH levels representing more favorable biology.

No significant financial relationships to disclose.

[Table: see text]

BAY 43–9006 (sorafenib-BAY) alters proliferation pathways and mutant specific-PCR (MS-PCR) improves detection of BRAF mutations in metastatic melanoma (MM)

8542

Background: Approximately 60% of melanomas carry BRAF mutations (mut). BAY is a multi-kinase inhibitor that inhibits the BRAF pathway. A phase II trial of BAY in MM is being conducted to: 1) determine if treatment (tx) with BAY can alter proliferation as measured by cyclin D1, Ki-67 and ERK, 2) assess for differential anti-tumor responses and 3) to assess a newly developed fluorescent-based PCR assay to detect mutant BRAF. Methods: Eligibility criteria: Biopsy (bx)-accessible, untreated MM. Measurable disease (RECIST). Stratification of tumor BRAF status determined by routine PCR sequencing for codon 600 mut prior to tx and fluorescent MS-PCR sequencing for confirmation. MS-PCR specifically amplified the M-BRAF allele without amplifying the wild-type (WT)allele. Tx: BAY 400 mg po BID D1–28 q4w. Repeat bx on Day 28. Bx assessed for Ki-67, cyclin-D1 and ERK. Serum collagen cryptic epitopes were measured serially. Re-imaging was done every 2 cycles and pts treated until POD. Results: 29 pts (9-M1a, 8-M1b, 12-M1c) enrolled. 26 wild type (WT) and 3 mutant (M) BRAF by routine PCR. Due to the low yield of mut on routine PCR, MS-PCR was done. 6 mutants were detected in the first 16 pts with MS-PCR compared to 2 with routine sequencing. Median age: 68 (range 22–91). 8 pts with LDH ≥ 1.5 × nl. Tox: Gr I-diarrhea(7), alopecia(4), rash(6), mucositis(4), nausea(4), pain(4), hand-foot(2); Gr II- HTN(4), fatigue(2),mucositis(1), rash(3), pain(3), hand-foot(2); Gr III-hand-foot(1), rash(1), fatigue(1) and intestinal perforation(1). Responses: 12 NE (2 WD, 8 early POD, 1 tox, 1 too early); M BRAF- 1 PR (lymph nodes and large SQ arm masses) and 2 PD; WT BRAF- 1 PR, 7 POD after 2 cycles, 6 SD. Matched paired biopsies demonstrated down regulation of tumor ki-67, erk and cyclin-D1. Collagen cryptic epitopes correlated with tumor responses. Conclusions: MM patients with tumors that were molecularly characterized for BRAF mutational status were entered on this single agent BAY trial and responses were seen in both M and WT arms. Down-regulation of Ki-67, cyclin D1 and ERK was demonstrated and MS-PCR improved the sensitivity to detect BRAF mut. Supported by NCI N01-CM17103 and TRI.

No significant financial relationships to disclose.

A phase II trial of BAY 43–9006 in metastatic melanoma with molecularly characterized B-Raf status

8046

Background: BAY 43–9006 is a multikinase inhibitor. The RAS/BRAF/MEK/MAPK pathway (pw) is a major pw for transmitting extracellular growth factor signals to the nucleus. Activating mutations in any of the pw kinases would be expected to result in uncontrolled cell proliferation. Approximately 60% of melanomas carry B-Raf mutations. The primary trial goals are: 1) determine if treatment (tx) with BAY 43–9006 can disrupt the RAS/BRAF/MEK/MAPK pw by depleting intra-tumor stores of B-Raf and/or CDK4; and 2) determine if tx with BAY 43–9006 results in differential anti-tumor responses in pts whose tumors have been molecularly characterized. Methods: Eligibility criteria: Biopsy (bx)-accessible, untreated metastatic melanoma. Measurable disease (RECIST). Adequate hematologic and serologic parameters. Signed ICF. All pts had tumor bx for B-Raf status determined by PCR sequencing prior to tx. Exon 3 of N-Ras and exon 15 of B-Raf were sequenced. Pts stratified by B-Raf. Tx: BAY 43–9006 was administered at 400 mg po BID. D1–28 q4w. Repeat bx was done on Day 28. Re-imaging was done every 2 cycles and pts treated until POD. Stats: Stratification by B-Raf mutation status. 2 stage study design with accrual of 13 pts/arm in first stage and total of 29 pts/arm if ≥ 1 objective response (OR) in initial cohort. Results: 8 pts (2-M1a, 1-M1b, 5-M1c) enrolled. 7 wild type (WT) and 1 mutant (M) B-Raf. Median age: 54 (range 22–91). No pts with LDH ≥ 1.5 × nl. 2 withdrew prior to tx. Responses: M B-Raf (1 evaluable)-PR (lymph nodes and large SQ arm masses); WT B-Raf-1 POD during cycle 1 (NE), 1PD, 3 too early. Toxicity: Grade I diarrhea, Grade II hypertension, fatigue and oral mucositis. Correlative immunoassays of tumor B-Raf, CDK4, phospho-MAPK and cyclin-D1 and correlation of DNA extracted from peripheral blood cells assayed by fluorescent, mutant-specific PCR and tumor B-RAF are being evaluated. Conclusions: This Phase II trial will molecularly characterize tumors for B-Raf status prior to tx with BAY 43–9006 and assess the effects on Ras-Raf signaling and correlate clinical responses. This trial will address potential differences in sensitivity to BAY 43–9006 based on B-Raf. While premature, 1 pt with M B-Raf has had an OR with a significant decrease in tumor volume. Supported by NCI N01-CM17103 and TRI.

No significant financial relationships to disclose.

Phase II trial of iboctadekin (rhIL-18) on a daily X 5 schedule in metastatic melanoma (MM)

10043

Background: Interleukin-18 (IL-18) is an immunostimulatory cytokine with potent antitumor activity in preclinical models. Two phase I studies of recombinant human (rh) IL-18 explored a wide dose range (0.03–1.0 mg/kg) without reaching a maximum tolerated dose (MTD) on the daily × 5 schedule. Pharmacodynamic data including inflammatory cytokine production and activation of lymphocyte subsets revealed optimal biologic activity at the lower end of the dose range (0.01–0.2 mg/kg) as did 2 unconfirmed partial responses (PRs) in a MM and a renal cancer patient (pt) at 0.1 mg/kg. Methods: An open-label, randomized, phase II trial in 60 adult pts with previously untreated MM was conducted to evaluate the efficacy and safety of rhIL-18 administered as a 2-hour IV infusion daily × 5 every 28 days for 6 cycles. Pts with PS ≤ 1, without known CNS involvement, and with adequate end organ function were randomized in stage 1 to 3 dose levels of IL-18 stratified according to AJCC M stage 1a/b vs. 1c. Two confirmed responses for a given dose level in Stage 1 were required to enroll 20 additional pts/level in Stage 2. The 1° objective was determination of overall response rate (ORR) for each dose level. Progression-free survival (PFS), tolerability, and immunogenicity were 2° endpoints. Results: 64 pts were treated at 3 dose levels. Nine pts remain on study. One pt experienced a confirmed PR. Based on preliminary data, the difference in PFS 6 months (mos) was significant (p=0.03) for 0.01 vs 0.1 mg/kg. Most common toxicities were mild to moderate fever, rigors, chills, n/v, and headache. Anti-IL18 antibody (Ab) development correlated with dose level. No clinically significant adverse events were associated with Ab development. Conclusion: Iboctadekin has an acceptable tolerability profile and has activity in MM but insufficient confirmed responses have been observed at this time to initiate Stage 2. Preliminary PFS 6 months indicates an advantage for pts treated at the lowest dose.

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