Prognostic implication of KIT mutations in melanoma

9049

Background: The natural history of BRAF and NRAS mutant (mut) melanoma (mel) has been described, but prognostic implications of KIT mut mel have not. Methods: We performed a single-center retrospective review of 180 patients (pts) enriched for mucosal, acral or chronic sun-damaged skin (CSD) mel and screened for KIT, BRAF, and NRAS mut from 4/07 - 4/10 as a part of a phase II imatinib study. Pt/disease characteristics were compared using the Kruskal-Wallis or Chi-square tests. Factors associated with outcomes were assessed by Kaplan-Meier methods and multivariable Cox regression. Results: Median age, 63.7 years; 54.4% male. Primary site: 40% mucosal, 29% acral, 22% CSD, 9% others. Mut rate: 18% KIT, 16% BRAF, 14% NRAS, 52% wild-type (wt). Pathologic subtype differed by genetic subgroup (p<.001) while age, gender, and stage did not (all p>0.05). 18/26 (69%) KIT mut pts received imatinib in the metastatic (met) setting; 6/18 received > 1 other KIT inhibitor. 3/25 (12%) BRAF mut pts received vemurafenib. 8/27 (30%) KIT mut, 4/27 (15%) BRAF mut, 6/20 (30%) NRAS mut, and 6/20 (30%) wt pts received ipilimumab. 149/180 (83%) pts developed mets at a median of 2.15 years (95% CI: 1.72, 2.72). Median follow-up (FU) of pts not developing mets was 3.91 yrs (range: 0.25, 14.34). Older age (HR: 1.02, 95% CI: 1.00, 1.03) and pathologic subtype (mucosal vs CSD HR: 1.70, 95% CI: 1.02, 2.84; non-CSD/unknown vs CSD HR: 2.05, 95% CI: 1.00, 4.21) were associated with increased risk of mets but not with time from mets to death. Of 149 pts who progressed, 123 (83%) died during FU. Median time from met to death was 1.21 years (95% CI: 0.91, 1.67). Median FU from time of mets among those alive at last FU was 2.53 yrs (range: 0.06, 6.85). Mut status including KIT mut was not associated with time to first met or time from met to death. Pts who received ipilimumab from time of first distant met had reduced risk of death (HR: 0.55, 95% CI: 0.36, 0.87) independent of mut status. No impact was observed with KIT inhibition. Conclusions: KIT mut status is not an independent predictor of time to mets or survival in pts with mets. Ipilimumab improved pt outcomes regardless of mut status. The lack of impact of KIT inhibitors is likely due to the heterogeneity of KIT mut in mel but does not preclude efficacy in appropriately selected pts.

Phase II study of selumetinib (sel) versus temozolomide (TMZ) in gnaq/Gna11 (Gq/11) mutant (mut) uveal melanoma (UM)

CRA9003

The full, final text of this abstract will be available at abstract.asco.org at 7:30 AM (EDT) on Saturday, June, 1, 2013, and in the Annual Meeting Proceedings online supplement to the June 20, 2013, issue of Journal of Clinical Oncology. Onsite at the Meeting, this abstract will be printed in the Saturday edition of ASCO Daily News.

Vemurafenib (VEM) in patients (pts) with BRAF-mutant melanoma and brain metastases (mets)

9060

Background: Emerging data suggest that RAF inhibitors are an effective therapy for pts with BRAF-mutant melanoma and brain mets. Although reported efficacy is encouraging, these data are derived from case reports or early stage trials enriched with physiologically fit pts. It is therefore of interest to assess the “real world” experience of VEM in this population. Methods: Records of all BRAF-mutant melanoma pts treated with RAF inhibitors at our center from 2007 to 2012 were reviewed retrospectively. We determined the best overall response rate (BORR) and, when applicable, the overrall intracranial response rate (OIRR) by RECIST v1.1, progression-free survival (PFS), and overall survival (OS) to RAF inhibition. Pretreatment formalin-fixed, paraffin-embedded tumor was assessed using an exon capture assay able to sequence coding exons of 279 cancer-associated genes. Results: 21 (18%) of 119 pts with BRAF-mutant melanoma treated with VEM had active brain mets (age range: 25-86, sex: 52% men, median ECOG PS: 1, proportion with extracranial mets: 90%, BRAF mutation: 86% V600E and 14% V600K). 10/21 pts had no prior intracranial (IC) therapy; 11/21 pts received whole brain radiotherapy (WBRT, 7/21), stereotactic radiosurgery (1/21), metastasectomy (2/21) or multimodality therapy (1/21) prior to VEM. 12/21 pts received ipilimumab sometime during their disease course. For radiographically evaluable pts (N=17), the BORR was 65% (95% CI: 43-88) and the OIRR was 40% (95% CI: 15-65). For 4 pts, the BORR and OIRR were discordant−3 pts had IC progression but visceral tumor shrinkage, 1 pt had IC disease control but visceral progression. VEM was effective in pts whether or not they had received prior local brain therapy. The estimated median PFS and OS for all brain mets pts (N=21) were 4 and 8 months, respectively. Pretreatment tumor is available for exon sequencing in approximately half of these patients. This analysis is ongoing. Conclusions: In routine clinical practice, the OIRR to VEM was 40% which is higher than historical response rates to WBRT. VEM may be preferable to WBRT as a first-line therapy for pts with BRAF-mutant melanoma and brain mets. Whether RAF inhibitor treatment improves OS in this population will require further study.

An update on BREAK-3, a phase III, randomized trial: Dabrafenib (DAB) versus dacarbazine (DTIC) in patients with BRAF V600E-positive mutation metastatic melanoma (MM)

9013

Background: Dabrafenib is a selective BRAF inhibitor with demonstrated efficacy in BRAF V600E-positive mutation in MM. The primary analysis of BREAK-3 (NCT01227889) compared progression-free survival (PFS) in patients (pts) with BRAF V600E-positive mutation MM treated with dabrafenib or DTIC. Methods: Median PFS for dabrafenib of 5.1 months (mo) and study methods were previously described (Hauschild A, et al. Lancet. 2012,380:358–365). Independent review ended at the primary analysis. PFS was updated in Jun 2012 at median follow-up of 10.5 mo for dabrafenib (67% of PFS events), and 9.9 mo for DTIC. Median overall survival (OS) was not reached, so another analysis of OS and safety was performed with data as of Dec 2012, at which time the median follow-up was 15.2 (dabrafenib) and 12.7 (DTIC) mo. PFS of subjects who crossed over was also evaluated at that time. Results: PFS hazard ratio was 0.37 [95% CI; 0.23, 0.57]; median PFS was 6.9 mo dabrafenib and 2.7 mo DTIC. In Dec 2012, 36/63 DTIC pts crossed over; median PFS was 4.3 [95% CI; 4.1, 6.1] mos. OS is presented in the Table.The four most common adverse events (AE) on the dabrafenib arm were hyperkeratosis (39%), headache (35%), arthralgia (35%), and pyrexia (32%). Serious AEs ≥ 5% on the dabrafenib arm included cutaneous squamous cell carcinoma/keratoacanthoma (10%) and pyrexia (5%). Conclusions: Longer follow-up confirms the benefits of dabrafenib on PFS and response rate. Median OS in the dabrafenib arm was over 18 mo and over 15 mo in the DTIC arm. OS results are confounded by crossover of DTIC pts to dabrafenib and likely by subsequent therapy after progression. The effects of subsequent therapy results will be investigated. The safety profile had no significant changes. Clinical trial information: NCT01227889. [Table: see text]

Phase II trial of MEK inhibitor selumetinib (AZD6244, ARRY-142886) in patients with BRAFV600E/K-mutated melanoma

PURPOSE

Test the hypothesis that in BRAF-mutated melanomas, clinical responses to selumetinib, a MEK inhibitor, will be restricted to tumors in which the PI3K/AKT pathway is not activated.

EXPERIMENTAL DESIGN

We conducted a phase II trial in patients with melanoma whose tumors harbored a BRAF mutation. Patients were stratified by phosphorylated-AKT (pAKT) expression (high vs. low) and treated with selumetinib 75 mg per os twice daily. Pretreatment tumors were also analyzed for genetic changes in 230 genes of interest using an exon-capture approach.

RESULTS

The high pAKT cohort was closed after no responses were seen in the first 10 patients. The incidence of low pAKT melanoma tumors was low (∼25% of melanomas tested) and this cohort was eventually closed because of poor accrual. However, among the five patients with melanoma accrued in the low pAKT cohort, there was one partial response (PR). Two other patients had near PRs before undergoing surgical resection of residual disease (one patient) or discontinuation of treatment due to toxicity (one patient). Among the two nonresponding, low pAKT patients with melanoma, co-mutations in MAP2K1, NF1, and/or EGFR were detected.

CONCLUSIONS

Tumor regression was seen in three of five patients with BRAF-mutated, low pAKT melanomas; no responses were seen in the high pAKT cohort. These results provide rationale for co-targeting MEK and PI3K/AKT in patients with BRAF mutant melanoma whose tumors express high pAKT. However, the complexity of genetic changes in melanoma indicates that additional genetic information will be needed for optimal selection of patients likely to respond to MEK inhibitors.

Abstract 2284: Phase II trial of MEK inhibitor selumetinib (AZD6244) in patients with BRAFV600E/K- or NRAS-mutated melanoma

Our pre-clinical in vitro data suggested that all BRAF-mutated cell lines, and some NRAS-mutated melanoma are sensitive to MEK inhibition. BRAFwt/NRASwt were uniformly resistant. Among the sensitive cell lines, those with enhanced activation of the PI3K/AKT pathway did not undergo apoptosis. This is consistent with a recent phase II trial with Selumetinib, an allosteric MEK inhibitor, which showed a 6% response rate in unselected melanoma patients. Retrospectively, 5 of 6 of the responders were found to harbor BRAFV600E mutations. We hypothesized that treatment of BRAF-mutated or NRAS-mutated melanomas with Selumetinib will induce clinical responses only in the subset of tumors in which the PI3K/AKT pathway is not activated. In this phase II trial, melanoma patients with either BRAF or NRAS mutation were stratified based on phospho-AKT (pAKT) expression (high vs. low), as measured by immunohistochemistry staining of pre-treatment tumor specimens. Patients were treated with Selumetinib 75 mg p.o. daily in 28-day cycles. We found that the incidence of high pAKT melanoma tumors was about 4 times higher than low pAKT tumors. None of the 10 patients in the high pAKT cohort responded, although 4 patients showed stable disease for ≥4 months. This cohort was closed to further accrual. In contrast, in the low pAKT group, 1 patient had a true partial response (PR) and 2 others had near PRs. One of these patients had to discontinue treatment due to toxicity; the other had his remaining tumor resected. This cohort was closed due to slow patient accrual. We used an exon capture, next-generation sequencing assay to define the mutational status of 230 cancer associated genes in pre-treatment tumors, derived from patients belonging to both cohorts. The assay detects point mutations, small indels and copy number alterations. Among the two low pAKT patients who were resistant to MEK inhibition, one had a mutation in MAP2K1 that encodes for a K57N mutation in helix A of MEK1. We speculate that this is an activating mutation, since a missense mutation in the amino acid just proximal (Q56P) was previously shown to be highly activating. The other non-responding patient in the low pAKT cohort had an activating mutation in EGFR. Both of these could drive increased activation of the MAPK pathway, thus explaining the resistance to the drug. We conclude that future trials with MEK inhibitors in melanoma should exclude patients with high pAKT tumors. The occurrence of complex genetic changes in melanoma requires studies to better stratify the patients according the prediction of response to MEK inhibitors.

Citation Format: Federica Catalanotti, David B. Solit, Melissa P. Pulitzer, Michael F. Berger, Sasinya N. Scott, Tunc Iyriboz, Mario E. Lacouture, Katherine S. Panageas, Jedd D. Wolchok, Richard D. Carvajal, Gary K. Schwartz, Neal Rosen, Paul B. Chapman. Phase II trial of MEK inhibitor selumetinib (AZD6244) in patients with BRAFV600E/K- or NRAS-mutated melanoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2284. doi:10.1158/1538-7445.AM2013-2284

Mechanisms of resistance to RAF inhibition in melanomas harboring a BRAF mutation

Treatment of V600E/K BRAF-mutated melanomas with RAF inhibitors (either vemurafenib or dabrafenib) results in rapid and dramatic responses in most patients-results that are associated with improved progression-free survival (PFS) and in the case of vemurafenib, overall survival (OS). However, resistance develops at a median time of approximately 6 months. Understanding the mechanisms of resistance is critical to develop strategies to prolong PFS and OS. Negative feedback mechanisms inherent in the MAPK pathway serve to modulate responses to these drugs. However, genetic changes develop within the tumor, which lead to reactivation of the MAPK and resistance to these drugs. The mechanisms that have been demonstrated in many patients by multiple investigators are (1) development of an activating mutation in NRAS, and (2) appearance of a BRAFV600E splice variant that encourages RAF dimerization. Several other mechanisms of resistance have also been described in individual patients or in preclinical models of resistance. In addition, there is evidence that activation of parallel pathways, such as the PI3K/AKT pathway, may represent another mechanism of resistance. Understanding the various mechanisms of resistance will inform our attempts to prevent resistance to RAF inhibitors.

Progression of RAS-mutant leukemia during RAF inhibitor treatment

Vemurafenib, a selective RAF inhibitor, extends survival among patients with BRAF V600E-mutant melanoma. Vemurafenib inhibits ERK signaling in BRAF V600E-mutant cells but activates ERK signaling in BRAF wild-type cells. This paradoxical activation of ERK signaling is the mechanistic basis for the development of RAS-mutant squamous-cell skin cancers in patients treated with RAF inhibitors. We report the accelerated growth of a previously unsuspected RAS-mutant leukemia in a patient with melanoma who was receiving vemurafenib. Exposure to vemurafenib induced hyperactivation of ERK signaling and proliferation of the leukemic cell population, an effect that was reversed on drug withdrawal.

Dabrafenib in patients with Val600Glu or Val600Lys BRAF-mutant melanoma metastatic to the brain (BREAK-MB): a multicentre, open-label, phase 2 trial

BACKGROUND

Brain metastases are common in patients with metastatic melanoma and median overall survival from their diagnosis is typically 17-22 weeks. We assessed dabrafenib in patients with Val600Glu or Val600Lys BRAF-mutant melanoma metastatic to the brain.

METHODS

We undertook a multicentre, open-label, phase 2 trial in 24 centres in six countries. We enrolled patients with histologically confirmed Val600Glu or Val600Lys BRAF-mutant melanoma and at least one asymptomatic brain metastasis (≥5 mm and ≤40 mm in diameter). Eligible patients were aged 18 years or older, had an Eastern Cooperative Oncology Group performance status of 0 or 1, and had adequate organ function. Patients were split into two cohorts: those in cohort A had not received previous local treatment for brain metastases and those in cohort B had progressive brain metastases after previous local treatments. Patients received 150 mg oral dabrafenib twice a day until disease progression, death, or unacceptable adverse events. The primary endpoint was the proportion of patients with Val600Glu BRAF-mutant melanoma who achieved an overall intracranial response, which was defined as a complete response or partial response assessed with a modified form of Response Evaluation Criteria in Solid Tumors (RECIST 1.1). We included patients who received at least one dose of dabrafenib in efficacy and safety analyses. This study is registered with ClinicalTrials.gov, number NCT01266967.

FINDINGS

Between Feb 2, 2011, and Aug 5, 2011, we enrolled 172 patients: 89 (52%) in cohort A and 83 (48%) in cohort B. 139 (81%) had Val600Glu BRAF-mutant melanoma. 29 (39·2%, 95% CI 28·0-51·2) of 74 patients with Val600Glu BRAF-mutant melanoma in cohort A achieved an overall intracranial response, as did 20 (30·8%, 19·9-43·4) of 65 in cohort B. One (6·7%, 0·2-31·9) of 15 patients with Val600Lys BRAF-mutant melanoma achieved an overall intracranial response in cohort A, as did four (22·2%, 6·4-47·6) of 18 such patients in cohort B. Treatment-related adverse events of grade 3 or worse occurred in 38 (22%) patients. Eleven (6%) patients developed squamous-cell carcinoma (five [6%] patients in cohort A, of whom one also had keratoacanthoma; six [7%] in cohort B). Four grade 4 treatment-related adverse events occurred in cohort A: one blood amylase increase, one convulsion, one lipase increase, and one neutropenia. Two grade 4 events occurred in cohort B: one agranulocytosis and one intracranial haemorrhage. 51 (30%) patients had a serious adverse event. The three most frequent serious adverse events were pyrexia (ten [6%] patients), intracranial haemorrhage (ten [6%]; one treatment-related), and squamous-cell carcinoma (11 [6%]).

INTERPRETATION

Dabrafenib has activity and an acceptable safety profile in patients with Val600Glu BRAF-mutant melanoma and brain metastases irrespective of whether they are untreated or have been previously treated but have progressed.

FUNDING

GlaxoSmithKline.

Melanoma exosomes educate bone marrow progenitor cells toward a pro-metastatic phenotype through MET

Tumor-derived exosomes are emerging mediators of tumorigenesis. We explored the function of melanoma-derived exosomes in the formation of primary tumors and metastases in mice and human subjects. Exosomes from highly metastatic melanomas increased the metastatic behavior of primary tumors by permanently 'educating' bone marrow progenitors through the receptor tyrosine kinase MET. Melanoma-derived exosomes also induced vascular leakiness at pre-metastatic sites and reprogrammed bone marrow progenitors toward a pro-vasculogenic phenotype that was positive for c-Kit, the receptor tyrosine kinase Tie2 and Met. Reducing Met expression in exosomes diminished the pro-metastatic behavior of bone marrow cells. Notably, MET expression was elevated in circulating CD45(-)C-KIT(low/+)TIE2(+) bone marrow progenitors from individuals with metastatic melanoma. RAB1A, RAB5B, RAB7 and RAB27A, regulators of membrane trafficking and exosome formation, were highly expressed in melanoma cells. Rab27A RNA interference decreased exosome production, preventing bone marrow education and reducing, tumor growth and metastasis. In addition, we identified an exosome-specific melanoma signature with prognostic and therapeutic potential comprised of TYRP2, VLA-4, HSP70, an HSP90 isoform and the MET oncoprotein. Our data show that exosome production, transfer and education of bone marrow cells supports tumor growth and metastasis, has prognostic value and offers promise for new therapeutic directions in the metastatic process.

Dabrafenib in BRAF-mutated metastatic melanoma: a multicentre, open-label, phase 3 randomised controlled trial

BACKGROUND

Dabrafenib, an inhibitor of mutated BRAF, has clinical activity with a manageable safety profile in studies of phase 1 and 2 in patients with BRAF(V600)-mutated metastatic melanoma. We studied the efficacy of dabrafenib in patients with BRAF(V600E)-mutated metastatic melanoma.

METHODS

We enrolled patients in this open-label phase 3 trial between Dec 23, 2010, and Sept 1, 2011. This report is based on a data cutoff date of Dec 19, 2011. Patients aged 18 years or older with previously untreated, stage IV or unresectable stage III BRAF(V600E) mutation-positive melanoma were randomly assigned (3:1) to receive dabrafenib (150 mg twice daily, orally) or dacarbazine (1000 mg/m(2) intravenously every 3 weeks). Patients were stratified according to American Joint Committee on Cancer stage (unresectable III+IVM1a+IVM1b vs IVM1c). The primary endpoint was investigator-assessed progression-free survival and was analysed by intention to treat; safety was assessed per protocol. This study is registered with ClinicalTrials.gov, number NCT01227889.

FINDINGS

Of the 733 patients screened, 250 were randomly assigned to receive either dabrafenib (187 patients) or dacarbazine (63 patients). Median progression-free survival was 5·1 months for dabrafenib and 2·7 months for dacarbazine, with a hazard ratio (HR) of 0·30 (95% CI 0·18-0·51; p<0·0001). At data cutoff, 107 (57%) patients in the dabrafenib group and 14 (22%) in the dacarbazine group remained on randomised treatment. Treatment-related adverse events (grade 2 or higher) occurred in 100 (53%) of the 187 patients who received dabrafenib and in 26 (44%) of the 59 patients who received dacarbazine. The most common adverse events with dabrafenib were skin-related toxic effects, fever, fatigue, arthralgia, and headache. The most common adverse events with dacarbazine were nausea, vomiting, neutropenia, fatigue, and asthenia. Grade 3-4 adverse events were uncommon in both groups.

INTERPRETATION

Dabrafenib significantly improved progression-free survival compared with dacarbazine.

FUNDING

GlaxoSmithKline.

Tumour micro-environment elicits innate resistance to RAF inhibitors through HGF secretion

Drug resistance presents a challenge to the treatment of cancer patients. Many studies have focused on cell-autonomous mechanisms of drug resistance. By contrast, we proposed that the tumour micro-environment confers innate resistance to therapy. Here we developed a co-culture system to systematically assay the ability of 23 stromal cell types to influence the innate resistance of 45 cancer cell lines to 35 anticancer drugs. We found that stroma-mediated resistance is common, particularly to targeted agents. We characterized further the stroma-mediated resistance of BRAF-mutant melanoma to RAF inhibitors because most patients with this type of cancer show some degree of innate resistance. Proteomic analysis showed that stromal cell secretion of hepatocyte growth factor (HGF) resulted in activation of the HGF receptor MET, reactivation of the mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3-OH kinase (PI(3)K)-AKT signalling pathways, and immediate resistance to RAF inhibition. Immunohistochemistry experiments confirmed stromal cell expression of HGF in patients with BRAF-mutant melanoma and showed a significant correlation between HGF expression by stromal cells and innate resistance to RAF inhibitor treatment. Dual inhibition of RAF and either HGF or MET resulted in reversal of drug resistance, suggesting RAF plus HGF or MET inhibitory combination therapy as a potential therapeutic strategy for BRAF-mutant melanoma. A similar resistance mechanism was uncovered in a subset of BRAF-mutant colorectal and glioblastoma cell lines. More generally, this study indicates that the systematic dissection of interactions between tumours and their micro-environment can uncover important mechanisms underlying drug resistance.

Phase III, randomized, open-label, multicenter trial (BREAK-3) comparing the BRAF kinase inhibitor dabrafenib (GSK2118436) with dacarbazine (DTIC) in patients with BRAFV600E-mutated melanoma

LBA8500^

Background: Dabrafenib, a selective BRAF inhibitor, has shown activity with a manageable safety profile in phase I/II studies in patients (pts) with BRAFV600E-mutated metastatic melanoma (MM). This phase III trial (NCT01227889) compared progression-free survival (PFS) in pts with advanced MM treated either with dabrafenib or dacarbazine (DTIC). Methods: Pts with previously untreated, unresectable stage III or IV BRAFV600E-mutated melanoma were randomized (3:1) and stratified by stage to dabrafenib (150 mg po bid) or DTIC (1000 mg/m2, IV, q3w). Primary endpoint was investigator-assessed PFS. Primary analysis for PFS was planned after 102 events. Pts on the DTIC arm were allowed to cross over once progression was confirmed by independent review (IR). Secondary endpoints included PFS by IR, overall survival (OS), response rate (RR), duration of response, safety and pharmacokinetics. Results: 250 pts were enrolled at 93 centers globally from February to September 2011. 187 were randomized to dabrafenib and 63 to DTIC. 141pts were on study treatment at the data cut-off at December 19, 2011 (dabrafenib n = 127; DTIC n = 14), including 21/28 DTIC pts crossed over to dabrafenib. Median age was 52 years, 31% of pts were ECOG >1, 66% M1c, 33% LDH > ULN. Demographics were well balanced between the two arms. At the time of the primary analysis, there were 118 events (77 dabrafenib and 41 DTIC). The hazard ratio for PFS was 0.30 (95% CI: 0.18–0.53; p < 0.0001). Median PFS was 5.1 months for dabrafenib and 2.7 for DTIC. OS data were immature, with 30 deaths reported. Confirmed RR was 53% for dabrafenib and 19% for DTIC. Benefits in PFS and RR were observed in all subgroups evaluated. Common adverse events (AEs) on the dabrafenib arm were hyperkeratosis (37%), headache (32%), pyrexia (28%), arthralgia (27%), skin papillomas (24%). Serious AEs (> 1%) on the dabrafenib arm included pyrexia (4%), squamous cell carcinomas (6%), and new primary melanomas (2%). Conclusions: Dabrafenib demonstrated a significant improvement in PFS and ORR over DTIC with an acceptable safety profile.

BREAK-MB: A phase II study assessing overall intracranial response rate (OIRR) to dabrafenib (GSK2118436) in patients (pts) with BRAF V600E/k mutation-positive melanoma with brain metastases (mets)

8501

Background: Melanoma brain mets carry a poor prognosis (median survival ≤4 months), for which more effective therapies are needed. Dabrafenib is a potent, selective oral inhibitor of mutated BRAF that has demonstrated clinical efficacy in pts with BRAF V600E/K mutant melanoma and previously untreated brain mets in a phase I study. Therefore, a phase II study (BREAK-MB) was initiated. Methods: Stage IV pts with ≥ 1 intracranial met (0.5 cm–4 cm assessed by MRI) without prior brain therapy (Cohort A) or with progression following prior brain therapy (Cohort B) were eligible with V600E/K mutation. Pts received dabrafenib 150 mg BID. The primary endpoint was investigator-assessed OIRR among V600E mutation-positive pts. Results: Overall, 172 pts were recruited. At interim analysis, of 127 pts enrolled (safety population), 41 (Cohort A n=24; Cohort B n=17) had reached 8-week disease assessment. Unconfirmed OIRR in Cohort A was 10/19, (53%; 95% CI: 28.9–75.6%) for V600E and 1/5 (20%; 95% CI: 0.5–71.6%) for V600K pts. In Cohort B unconfirmed OIRR was 8/15 (53%; 95% CI: 26.6%–78.7%) for V600E and 1/2 (50%; 95% CI: 1.3–98.7%) for V600K pts. Unconfirmed overall response rate (ORR) in Cohort A was 10/19 (53%; 95% CI: 28.9–75.6%) for V600E and 1/5 (20%; 95% CI: 0.5–71.6%) for V600K pts. In Cohort B unconfirmed ORR was 6/15 (40%; 95% CI: 16.3–67.7%) for V600E and 1/2 (50%; 95% CI: 1.3–98.7%) for V600K pts. In the safety population, 12/63 pts (19%) in Cohort A reported an SAE; 1 (2%) was fatal (cerebral hemorrhage). In Cohort B 15/64 pts (25%) reported an SAE; 1 (2%) was fatal (seizure). In Cohort A, 47 pts (75%) experienced AEs: 9 grade 3 (14%) and 3 grade 4 (5%). The most common AEs were headache (21%), hyperkeratosis and rash (17% each). In Cohort B, 47 pts (73%) experienced AEs: 12 grade 3 (19%) and 3 grade 4 (5%). The most common AEs were fatigue or nausea (22% each) and pyrexia (17%). Conclusions: Dabrafenib shows high clinical activity both in pts with intra- and extracranial mets with acceptable toxicity. Final data will be presented.

Pharmacodynamic activity of selumetinib to predict radiographic response in advanced uveal melanoma

8598

Background: Functionally activating mutations (mut) in Gnaq or Gna11, genes that encode for widely expressed G-protein alpha subunits, are early oncogenic events in uveal melanoma (UM) development and result in activation of the MAPK pathway. We previously demonstrated effective pathway inhibition with selumetinib (AZD6244, ARRY-142866) in UM cell lines, with decreased viability associated with pERK and cyclinD1 suppression (Ambrosini, AACR 2010). Methods: Using paired metastatic tumor biopsies from patients (pts) with radiographically progressing UM treated with selumetinib 75 mg BID on a phase II trial (NCT01143402), we correlated MAPK pathway inhibition with radiographic tumor regression and clinical benefit. Biopsies were performed at baseline and after 14 +/-1 days of treatment. Western blotting was performed for pERK and cyclinD1, and quantitated by densitometry. Response (RECIST 1.1) was assessed at baseline, week (wk) 4, wk 8, and q8wks subsequently. Radiographic regression was defined as greatest percentage shrinkage from baseline. Clinical benefit was defined as RECIST response or stable disease ≥16wks. Results: Paired tumor biopsies were assayed from 18 pts: median age 60 (range 47-81), M:F 11:7, median 1 prior therapy (range 0-2), 17 with liver involvement, Gnaq mut:Gna11 mut:wild-type 8:9:1. Radiographic regression was observed in 5 pts, with 2 achieving partial responses. 4 pts were on study ≥16wks (16+, 20, 25, 31 wks), with one currently on study at 11+ wks. Median pERK and cyclinD1 as measured by densitometry decreased by 48% (p=.03) and 76% (p=.03), respectively. Radiographic regression correlated with suppression of pERK (Spearmen’s rank correlation; p=0.04) but not cyclinD1 (p=0.38). A trend towards pERK suppression correlating with clinical benefit was observed (p=.07) with each of the 5 pts achieving PR or SD ≥16wks having a decrease of ≥30% in pERK from baseline. Conclusions: Selumetinib can inhibit pERK and cyclinD1 in UM and can result in tumor shrinkage. Sustained inhibition of pERK inhibition at day 14 may be predictive of benefit. Further evaluation of MEK inhibition in this disease is warranted.

Hypersensitivity skin reactions in melanoma patients treated with vemurafenib after ipilimumab therapy

8515

Background: Ipilimumab (IPI) and vemurafenib (VEM) each improve overall survival for patients (pts) with metastatic melanoma. Both are FDA-approved and are being used in pts with BRAFV600E-mutated metastatic melanoma. We previously described cases of prominent skin eruptions associated with VEM in pts who had previously received IPI. Methods: We have updated our experience of BRAFV600E-mutated melanoma pts treated with VEM who had previously received IPI. Pts were treated at our center from January 2007 to January 2012. Data were collected under an approved IRB waiver. Results: Sixteen melanoma pts were treated with VEM after having received IPI. The most common drug-related adverse event (AE) associated with VEM was rash, occurring in 13/16 patients (81.3%, 95% CI 56.5-93.2). Four pts developed a severe, Grade 3, maculopapular rash within 8 days of starting VEM. Biopsies in 2 pts revealed spongiotic and perivascular dermatitis with eosinophils consistent with a drug hypersensitivity reaction. Hypersensitivity reactions did not progress to life-threatening reactions such as anaphylaxis or Stevens-Johnson syndrome, nor did they result in VEM dose discontinuation. Reactions were managed with corticosteroids and dose modifications. Grade 3 rash strongly correlated with initiating VEM within one month of IPI (Fisher’s exact test, p = 0.007) and was not associated with the dose of prior IPI, the number of prior doses, or immune-related AEs. The incidence of Grade 3 rash in this pt cohort was significantly higher than in pts treated on the phase III trial of VEM (4/16, 25% versus 28/336, 8%; χ2 = 5.13, Df = 1, p = 0.02). The objective overall response for VEM was 50% (95% CI 26.5-73.4), which is similar to response rates seen on the phase II and III trials. Conclusions: In pts receiving VEM who have previously received IPI, dermatologic AEs appear to be more common. This effect seemed most pronounced if VEM was given within one month of completing IPI. Although more data are necessary to confirm this apparent association, we speculate that the release of immune checkpoint inhibition by IPI may predispose pts to hypersensitivity skin reactions to VEM.

Phase III, randomized, open-label, multicenter trial (BREAK-3) comparing the BRAF kinase inhibitor dabrafenib (GSK2118436) with dacarbazine (DTIC) in patients with BRAFV600E-mutated melanoma

LBA8500^

The full, final text of this abstract will be available at abstract.asco.org at 12:01 AM (EDT) on Monday, June 4, 2012, and in the Annual Meeting Proceedings online supplement to the June 20, 2012, issue of Journal of Clinical Oncology. Onsite at the Meeting, this abstract will be printed in the Monday edition of ASCO Daily News.

Ipilimumab in the treatment of uveal melanoma: The Memorial Sloan-Kettering Cancer Center experience

8549

Background: Ipilimumab (ipi) is an antibody that blocks cytotoxic T-lymphocyte antigen-4 (CTLA-4) and improves overall survival in patients (pts) with metastatic melanoma. Uveal melanoma (UM) is a rare and biologically unique disease subtype with no known effective systemic therapy. Ipi has proven efficacy in cutaneous melanoma (CM), but limited data exists regarding its activity in UM. We reviewed our single-institutional experience with ipi in advanced UM. Methods: After IRB approval, the MSKCC melanoma database was queried for patients with metastatic UM treated with ipi between 03/08-01/12. Radiographic response by RECIST and immune-related response criteria (irRC) was assessed by a single radiologist blinded to clinical outcomes. Immune-related adverse events (irAEs), survival and absolute lymphocyte count (ALC) were also evaluated. Results: 20 pts were identified: the median age was 61yrs (range 46-83), 55% were male, 85% had liver metastases, 60% had elevated LDH, and pts reported a median of 1 prior therapies (range 0-5). Pts received a median of 4 doses (range 1-16) of ipi. Response rates (RR) by irRC at 12 and 24 wks are listed below. Among pts with stable disease (SD) at 12 wks, the median time to progression was 30.6 wks (range 19.6-83), with one partial response (PR) occurring after 24 wks (overall RR 10%). Responses were observed in lung, liver and peritoneal metastases. Pts with an ALC ≥ 1.0 at 7 wks had a trend toward a higher clinical benefit (CB= CR + PR + SD) than pts with ALC < 1.0 (5/12 [42%] vs 0/5 [0%]; p= .09), consistent with prior studies in CM. To date, median survival for the group is 8.6 mos (95% CI, 3.5-NR), with two ongoing PRs (3+ yrs and 24+ wks). Reported irAEs include rash/pruritis (10/20), hepatitis (1/20), colitis (1/20), pancreatitis (1/20) and uveitis (1/20). Conclusions: Ipi has potential for benefit in pts with advanced UM; RR and irAE rates are similar to those observed in pts with advanced CM. Further evaluation of ipi in the treatment of UM, including identification of potential biomarkers of CB, is warranted. [Table: see text]

Updated overall survival (OS) results for BRIM-3, a phase III randomized, open-label, multicenter trial comparing BRAF inhibitor vemurafenib (vem) with dacarbazine (DTIC) in previously untreated patients with BRAFV600E-mutated melanoma

8502^

Background: We previously reported results of the planned OS interim analysis for BRIM-3 (50% of the planned 196 deaths required for final analysis) at which time the independent Data Safety Monitoring Board recommended release of results due to compelling efficacy (hazard ratio [HR] for death, 0.37 [95% CI 0.26–0.55]); p<0.0001 and PFS HR 0.26 [95% CI 0.20–0.33]; p<0.0001) and that DTIC-treated patients be permitted to cross over to receive vem. Median follow-up for vem patients was 3.75 months, and longer follow-up would estimate median OS more reliably. Updated OS with median 6.2 months follow-up and 199 total deaths showed HR for death 0.44 (95% CI 0.33–0.59) favoring vem and median OS for vem not reached. We report here the results of an updated OS analysis performed in Nov 2011 with ~10 months median follow-up on vem. Methods: 675 patients with previously untreated, unresectable Stage IIIC or IV melanoma that tested positive for BRAFV600E mutation by the cobas 4800 BRAF V600 Mutation Test were randomized (1:1) from Jan to Dec 2010 to vem (960 mg po bid) or DTIC (1000 mg/m2 IV q3w). Co-primary endpoints were OS and PFS. OS data for DTIC patients who crossed over to vem were censored at the time of crossover. Results: Median lengths of follow-up on vem and DTIC were 10.5 months (range 0.4–18.1) and 8.4 months (range <0.1–18.3), respectively. There were 334 deaths. Median OS rates with vem and DTIC were 13.2 months (95% CI 12.0–15.0) and 9.6 months (95% CI 7.9–11.8), respectively. 12-month OS rates were 55% for vem and 43% for DTIC. HR for death was 0.62 (95% CI 0.49–0.77) in favor of vem. 81 DTIC patients crossed over to vem. 44 (13%) vem and 65 (19%) DTIC patients received ipilimumab post-progression. Conclusions: With longer follow-up, vem treatment continues to be associated with improved OS in the BRIM-3 study. An updated analysis, with estimated median follow-up of ~13 months and including response data, will be conducted in Apr 2012 and presented at the meeting.

Abstract LB-428: RAS-independent dimerization of BRAF(V600E) splicing variants promotes resistance to RAF inhibitors

Over 50% of melanomas harbor activating mutations in BRAF, most commonly BRAF(V600E). Profound clinical activity has been observed with RAF inhibitors, including vemurafenib, which is now FDA approved for the treatment of patients with advanced melanomas whose tumors harbor a BRAF(V600E) mutation. RAF inhibitors affect ERK signaling in a mutation-specific manner: they inhibit ERK signaling in cells with BRAF(V600E), but paradoxically activate ERK signaling in cells with wild-type BRAF. We recently elucidated the mechanism of this phenomenon: activation of RAS promotes the dimerization of members of the RAF family. At non-saturating concentrations, binding of an ATP-competitive RAF inhibitor to one member of the dimer inhibits it, while also causing its transition to the activated state. This is associated with the allosteric transactivation of the other, non-drug bound member of the dimer. This leads to an overall increase in RAF specific activity and induction of ERK signaling. In BRAF(V600E) melanomas, RAS-GTP levels are low, BRAF(V600E) is found primarily as a monomer and RAF inhibitors effectively inhibit active BRAF(V600E) monomers. This model of RAF transactivation by RAF inhibitors predicts that any molecular lesion that enhances RAF dimerization will promote resistance to RAF inhibitors. To investigate mechanisms of acquired resistance to RAF inhibitors, we treated a sensitive BRAF(V600E) expressing melanoma cell line (SKME239) with the RAF inhibitor vemurafenib for 8 weeks and selected for resistant clones. We found that a subset of cells resistant to vemurafenib expressed a splicing variant form of BRAF(V600E) that lacked exons 4-8, a region that encompasses the RAS-binding domain. This form of BRAF(V600E) had a size of approximately 61KD (p61BRAF(V600E)). p61BRAF(V600E) exhibited enhanced dimerization as compared to full length BRAF(V600E) in cells with low levels of RAS-GTP. Ectopic expression of p61BRAF(V600E) conferred resistance to the RAF inhibitor. Moreover, a mutation that disrupts dimerization of p61BRAF(V600E) restored its sensitivity to vemurafenib. In tumors from patients that relapsed on vemurafenib we identified various splicing variants of BRAF(V600E), all of them lacking the RAS-binding domain (6/19). Disease progression samples obtained from a mutually exclusive subset (4/19) of the same group of patients harbored activating mutation in NRAS. We report the first RAF-inhibitor resistance mechanism that involves a structural change in BRAF and the first kinase inhibitor resistance mechanism that involves expression of aberrant splicing variants of the drug target. Tumors resistant to RAF inhibitors resulting from increased RAF dimerization retain sensitivity to inhibitors of downstream effectors of RAF such as MEK. Therefore, MEK inhibitors, if used in combination with RAF inhibitors, may delay or prevent the onset of this mechanism of resistance.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-428. doi:1538-7445.AM2012-LB-428

Histology and outcomes of newly detected lung lesions in melanoma patients

BACKGROUND

Melanoma frequently metastasizes to the lung. Improved radiologic techniques may decrease the need for biopsy of such lesions. The aim of this study was to examine factors predictive of a positive biopsy of melanoma.

METHODS

Using the Memorial Sloan-Kettering Cancer Center melanoma database, all patients with melanoma who had undergone biopsy of a suspicious new lung lesion from 1996 to 2009 were identified. Age, date of diagnosis, histology, and stage were obtained. Chart review was carried out to obtain medical history, smoking status, radiological appearance, and histology of lung lesions biopsied.

RESULTS

Two hundred and twenty-nine patients were identified; median age was 63 years; 48% were never smokers; 27% had a prior nonmelanoma cancer; 88% of lung nodules were malignant: 69% melanoma, 19% other cancers. Among 113 patients undergoing positron emission tomography (PET), proportions of benign, melanoma, and nonmelanoma 2-[fluorine-18]fluoro-2-deoxy-D-glucose-avid nodules did not differ (P = 0.53). On multivariable analysis, >stage I melanoma, negative smoking history, multiple lung nodules, and no prior nonmelanoma cancer were significantly associated with a melanoma biopsy result rather than other cancer.

CONCLUSIONS

In this study, 31% of lung lesions were not melanoma. In the subset undergoing PET, this did not differentiate between benign and malignant lesions. Biopsy is mandated in melanoma patients with new lung nodules.

RAS mutations in cutaneous squamous-cell carcinomas in patients treated with BRAF inhibitors

BACKGROUND

Cutaneous squamous-cell carcinomas and keratoacanthomas are common findings in patients treated with BRAF inhibitors.

METHODS

We performed a molecular analysis to identify oncogenic mutations (HRAS, KRAS, NRAS, CDKN2A, and TP53) in the lesions from patients treated with the BRAF inhibitor vemurafenib. An analysis of an independent validation set and functional studies with BRAF inhibitors in the presence of the prevalent RAS mutation was also performed.

RESULTS

Among 21 tumor samples, 13 had RAS mutations (12 in HRAS). In a validation set of 14 samples, 8 had RAS mutations (4 in HRAS). Thus, 60% (21 of 35) of the specimens harbored RAS mutations, the most prevalent being HRAS Q61L. Increased proliferation of HRAS Q61L-mutant cell lines exposed to vemurafenib was associated with mitogen-activated protein kinase (MAPK)-pathway signaling and activation of ERK-mediated transcription. In a mouse model of HRAS Q61L-mediated skin carcinogenesis, the vemurafenib analogue PLX4720 was not an initiator or a promoter of carcinogenesis but accelerated growth of the lesions harboring HRAS mutations, and this growth was blocked by concomitant treatment with a MEK inhibitor.

CONCLUSIONS

Mutations in RAS, particularly HRAS, are frequent in cutaneous squamous-cell carcinomas and keratoacanthomas that develop in patients treated with vemurafenib. The molecular mechanism is consistent with the paradoxical activation of MAPK signaling and leads to accelerated growth of these lesions. (Funded by Hoffmann-La Roche and others; ClinicalTrials.gov numbers, NCT00405587, NCT00949702, NCT01001299, and NCT01006980.).

Improved survival with vemurafenib in melanoma with BRAF V600E mutation

BACKGROUND

Phase 1 and 2 clinical trials of the BRAF kinase inhibitor vemurafenib (PLX4032) have shown response rates of more than 50% in patients with metastatic melanoma with the BRAF V600E mutation.

METHODS

We conducted a phase 3 randomized clinical trial comparing vemurafenib with dacarbazine in 675 patients with previously untreated, metastatic melanoma with the BRAF V600E mutation. Patients were randomly assigned to receive either vemurafenib (960 mg orally twice daily) or dacarbazine (1000 mg per square meter of body-surface area intravenously every 3 weeks). Coprimary end points were rates of overall and progression-free survival. Secondary end points included the response rate, response duration, and safety. A final analysis was planned after 196 deaths and an interim analysis after 98 deaths.

RESULTS

At 6 months, overall survival was 84% (95% confidence interval [CI], 78 to 89) in the vemurafenib group and 64% (95% CI, 56 to 73) in the dacarbazine group. In the interim analysis for overall survival and final analysis for progression-free survival, vemurafenib was associated with a relative reduction of 63% in the risk of death and of 74% in the risk of either death or disease progression, as compared with dacarbazine (P<0.001 for both comparisons). After review of the interim analysis by an independent data and safety monitoring board, crossover from dacarbazine to vemurafenib was recommended. Response rates were 48% for vemurafenib and 5% for dacarbazine. Common adverse events associated with vemurafenib were arthralgia, rash, fatigue, alopecia, keratoacanthoma or squamous-cell carcinoma, photosensitivity, nausea, and diarrhea; 38% of patients required dose modification because of toxic effects.

CONCLUSIONS

Vemurafenib produced improved rates of overall and progression-free survival in patients with previously untreated melanoma with the BRAF V600E mutation. (Funded by Hoffmann-La Roche; BRIM-3 ClinicalTrials.gov number, NCT01006980.).

KIT as a therapeutic target in metastatic melanoma

CONTEXT

Some melanomas arising from acral, mucosal, and chronically sun-damaged sites harbor activating mutations and amplification of the type III transmembrane receptor tyrosine kinase KIT. We explored the effects of KIT inhibition using imatinib mesylate in this molecular subset of disease.

OBJECTIVE

To assess clinical effects of imatinib mesylate in patients with melanoma harboring KIT alterations.

DESIGN, SETTING, AND PATIENTS

A single-group, open-label, phase 2 trial at 1 community and 5 academic oncology centers in the United States of 295 patients with melanoma screened for the presence of KIT mutations and amplification between April 23, 2007, and April 16, 2010. A total of 51 cases with such alterations were identified and 28 of these patients were treated who had advanced unresectable melanoma arising from acral, mucosal, and chronically sun-damaged sites.

INTERVENTION

Imatinib mesylate, 400 mg orally twice daily.

MAIN OUTCOME MEASURES

Radiographic response, with secondary end points including time to progression, overall survival, and correlation of molecular alterations and clinical response.

RESULTS

Two complete responses lasting 94 (ongoing) and 95 weeks, 2 durable partial responses lasting 53 and 89 (ongoing) weeks, and 2 transient partial responses lasting 12 and 18 weeks among the 25 evaluable patients were observed. The overall durable response rate was 16% (95% confidence interval [CI], 2%-30%), with a median time to progression of 12 weeks (interquartile range [IQR], 6-18 weeks; 95% CI, 11-18 weeks), and a median overall survival of 46.3 weeks (IQR, 28 weeks-not achieved; 95% CI, 28 weeks-not achieved). Response rate was better in cases with mutations affecting recurrent hotspots or with a mutant to wild-type allelic ratio of more than 1 (40% vs 0%, P = .05), indicating positive selection for the mutated allele.

CONCLUSIONS

Among patients with advanced melanoma harboring KIT alterations, treatment with imatinib mesylate results in significant clinical responses in a subset of patients. Responses may be limited to tumors harboring KIT alterations of proven functional relevance. Trial Registration clinicaltrials.gov Identifier: NCT00470470.

Abstract LB-419: An in-frame deletion in the N-terminal regulatory domain of BRAF(V600E) causes resistance to the RAF inhibitor PLX4032

Drugs that compete with ATP for binding to RAF selectively inhibit ERK signaling in tumor cells with BRAF(V600E) mutation. In BRAF wild-type cells, these compounds induce ERK signaling. RAF family members form dimers in a RAS-dependent manner. In BRAF wild-type cells, binding of RAF inhibitors to one member of the dimer transactivates the other, non-bound member. In contrast, in tumors with BRAF(V600E) mutation, RAS activity is too low to support dimer formation and the drug thus inhibits ERK signaling. This property of RAF inhibitors such as PLX4032 is believed to account for the wide therapeutic index of this drug and its remarkable clinical activity in patients with BRAF(V600E) melanomas. However, despite the initial effectiveness of PLX4032, resistance invariably develops. The dimerization model predicts that induction of RAS activity in the tumor will confer resistance. RAS mutation and activation of receptor tyrosine kinases (RTK) including PDGFRß and IGF1R have been implicated, as has induction of expression of the COT kinase, which drives RAF-independent ERK signaling. In order to identify novel mechanisms of RAF-inhibitor resistance, we generated PLX4032-resistant cell lines by prolonged exposure of sensitive BRAF mutant melanoma cells to the RAF inhibitor PLX4032. Analysis revealed that resistance of these clones was associated with failure of the drug to inhibit ERK signaling. PLX4032-resistant cells remained dependent on ERK signaling, as growth was inhibited by a MEK inhibitor, albeit at slightly higher doses. We did not detect RAS mutations, upregulation of receptor tyrosine kinases (RTK), or of other MEK kinases (CRAF, COT, Mos) in these cells. In a subset of resistant clones, we identified the expression of a variant form of BRAF(V600E), with an in-frame deletion within the N-terminal regulatory domain and a molecular weight of about 61KD (p61BRAF(V600E)). The N-terminal domain of RAF has been shown to negatively regulate the C-terminal catalytic domain, at least in part, by preventing dimerization. When expressed in 293H cells with intrincically low levels of RAS.GTP, dimerization of p61BRAF(V600E) is elevated compared to that of full-length BRAF(V600E). Expression of p61BRAF(V600E) in 293H cells rendered ERK signaling insensitive to inhibition by PLX4032, whereas a mutation in the dimerization domain of p61BRAF(V600E) restored sensitivity. Thus, in addition to BRAF gatekeeper mutations, there are at least three potential mechanisms that confer resistance by blunting the inhibition of RAF kinase by the inhibitor, all of which promote RAF dimerization: increased RAS.GTP due to RAS mutation or upstream (RTK) activation, RAF overexpression and deletion of the RAS binding domain within the N-terminus of RAF.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-419. doi:10.1158/1538-7445.AM2011-LB-419

Therapeutic implications of the emerging molecular biology of uveal melanoma

Uveal melanoma represents the most common primary intraocular malignancy in adults. Although uveal and cutaneous melanomas both arise from melanocytes, uveal melanoma is clinically and biologically distinct from its more common cutaneous counterpart. Metastasis occurs frequently in this disease, and once distant spread occurs, outcomes are poor. No effective systemic therapies are currently available; however, recent advances in our understanding of the biology of this rare and devastating disease, combined with the growing availability of targeted agents, which can be used to rationally exploit these findings, hold the promise for novel and effective therapies in the foreseeable future. Herein, we review our rapidly growing understanding of the molecular biology of uveal melanoma, including the pathogenic roles of GNAQ (guanine nucleotide binding protein q polypeptide)/11, PTEN (phosphatase and tensin homolog), IGF (insulin-like growth factor)/IGF-1 receptor, MET (hepatocyte growth factor), BAP1 [breast cancer 1, early onset (BRCA1)-associated protein-1], and other key molecules, potential therapeutic strategies derived from this emerging biology, and the next generation of recently initiated clinical trials for the treatment of advanced uveal melanoma.

Peptide-loaded Langerhans cells, despite increased IL15 secretion and T-cell activation in vitro, elicit antitumor T-cell responses comparable to peptide-loaded monocyte-derived dendritic cells in vivo

PURPOSE

We compared the efficacy of human Langerhans cells (LC) as tumor immunogens in vivo with monocyte-derived dendritic cells (moDC) and investigated how interleukin 15 (IL15) supports optimal DC-stimulated antitumor immunity.

EXPERIMENTAL DESIGN

American Joint Committee on Cancer stage III/IV melanoma patients participated in this first clinical trial comparing melanoma peptide-pulsed LC with moDC vaccines (NCT00700167, www.ClinicalTrials.gov). Correlative studies evaluated mechanisms mediating IL15 support of DC-stimulated antitumor immunity.

RESULTS

Both DC vaccines were safe and immunogenic for melanoma antigens. LC-based vaccines stimulated significantly greater tyrosinase-HLA-A*0201 tetramer reactivity than the moDC-based vaccines. The two DC subtypes were otherwise statistically comparable, in contrast to extensive prior data in vitro showing LC superiority. LCs synthesize much more IL15 than moDCs and stimulate significantly more antigen-specific lymphocytes with a cytolytic IFN-γ profile even without exogenous IL15. When supplemented by low-dose IL15, instead of IL2, moDCs stimulate 5 to 6 logs more tumor antigen-specific effector memory T cells (T(EMRA)) over 3 to 4 weeks in vitro. IL2 and IL15 can be synergistic in moDC stimulation of cytolytic T cells. IL15 promotes T-cell expression of the antiapoptotic bcl-2 and inhibits candidate regulatory T-cell (Treg) expansion after DC stimulation, countering two effects of IL2 that do not foster tumor immunity.

CONCLUSIONS

MoDC-based vaccines will require exogenous IL15 to achieve clinical efficacy. Alternatively, LCs can couple the endogenous production of IL15 with potent T-cell stimulatory activity. Optimization of full-length tumor antigen expression for processing into multiple immunogenic peptides for presentation by both class I and II MHC therefore merits emphasis to support more effective antitumor immunity stimulated by LCs.

Treatment implications of the emerging molecular classification system for melanoma

Melanoma is an aggressive disease with few standard treatment options. The conventional classification system for this disease is based on histological growth patterns, with division into four subtypes: superficial spreading, lentigo maligna, nodular, and acral lentiginous. Major limitations of this classification system are absence of prognostic importance and little correlation with treatment outcomes. Recent preclinical and clinical findings support the notion that melanoma is not one malignant disorder but rather a family of distinct molecular diseases. Incorporation of genetic signatures into the conventional histopathological classification of melanoma has great implications for development of new and effective treatments. Genes of the mitogen-associated protein kinase (MAPK) pathway harbour alterations sometimes identified in people with melanoma. The mutation Val600Glu in the BRAF oncogene (designated BRAF(V600E)) has been associated with sensitivity in vitro and in vivo to agents that inhibit BRAF(V600E) or MEK (a kinase in the MAPK pathway). Melanomas arising from mucosal, acral, chronically sun-damaged surfaces sometimes have oncogenic mutations in KIT, against which several inhibitors have shown clinical efficacy. Some uveal melanomas have activating mutations in GNAQ and GNA11, rendering them potentially susceptible to MEK inhibition. These findings suggest that prospective genotyping of patients with melanoma should be used increasingly as we work to develop new and effective treatments for this disease.

Dermatologic side effects associated with the MEK 1/2 inhibitor selumetinib (AZD6244, ARRY-142886)

BACKGROUND

Selumetinib (AZD6244, ARRY-142886) is a second generation MEK inhibitor that is currently in clinical trials for various solid malignancies. MEK kinase inhibitors are associated with dermatologic toxicities. While reactions affecting the skin, hair and nails to other targeted agents, such as epidermal growth factor receptor inhibitors (EGFRIs) have been abundantly described in recent years, the dermatologic toxicities associated with MEK inhibitors have not been well characterized. Similarly, their management may present a challenge in clinical trials. We reviewed the clinical presentation, evolution and management of dermatologic toxicities associated with selumetinib.

METHODS

A retrospective review of medical records of 11 patients referred to the Dermatology Service with dermatologic toxicities secondary to selumetinib was performed. Data from two phase II trials in which selumetinib was used to treat advanced metastatic cutaneous, mucosal, or uveal melanomas were reviewed. Parameters studied included the time to onset, clinical presentation, histology and management. In addition, the clinical database was accessed to retrieve clinical photographs when available.

RESULTS

Eight patients received selumetinib suspension orally at 100 mg twice a day and three patients received a newer capsule formulation at the maximum tolerated dose of 75 mg with the same frequency. The following adverse effects were observed: papulopustular rash (100%), xerosis (36%), pruritus (45%), fissures (9%), telangiectasias (27%), hyperpigmentation (9%), alopecia (9%), angular cheilitis (9%), and paronychia (9%). In addition, secondary bacterial infection with Staphylococcus aureus was documented in 3 patients (27%).

CONCLUSIONS

Dermatologic side-effects associated with selumetinib were similar to those seen with epidermal growth factor receptor inhibitors (EGFRIs). Treatment approaches used for EGFRI-induced dermatologic reactions may be potentially utilized to manage those associated with selumetinib.

Inhibition of mutated, activated BRAF in metastatic melanoma

BACKGROUND

The identification of somatic mutations in the gene encoding the serine-threonine protein kinase B-RAF (BRAF) in the majority of melanomas offers an opportunity to test oncogene-targeted therapy for this disease.

METHODS

We conducted a multicenter, phase 1, dose-escalation trial of PLX4032 (also known as RG7204), an orally available inhibitor of mutated BRAF, followed by an extension phase involving the maximum dose that could be administered without adverse effects (the recommended phase 2 dose). Patients received PLX4032 twice daily until they had disease progression. Pharmacokinetic analysis and tumor-response assessments were conducted in all patients. In selected patients, tumor biopsy was performed before and during treatment to validate BRAF inhibition.

RESULTS

A total of 55 patients (49 of whom had melanoma) were enrolled in the dose-escalation phase, and 32 additional patients with metastatic melanoma who had BRAF with the V600E mutation were enrolled in the extension phase. The recommended phase 2 dose was 960 mg twice daily, with increases in the dose limited by grade 2 or 3 rash, fatigue, and arthralgia. In the dose-escalation cohort, among the 16 patients with melanoma whose tumors carried the V600E BRAF mutation and who were receiving 240 mg or more of PLX4032 twice daily, 10 had a partial response and 1 had a complete response. Among the 32 patients in the extension cohort, 24 had a partial response and 2 had a complete response. The estimated median progression-free survival among all patients was more than 7 months.

CONCLUSIONS

Treatment of metastatic melanoma with PLX4032 in patients with tumors that carry the V600E BRAF mutation resulted in complete or partial tumor regression in the majority of patients. (Funded by Plexxikon and Roche Pharmaceuticals.)

Immunologic response to xenogeneic gp100 DNA in melanoma patients: comparison of particle-mediated epidermal delivery with intramuscular injection

PURPOSE

Prior studies show that i.m. injection of xenogeneic orthologues of melanosomal antigens (tyrosinase, gp100) induces CD8(+) T-cell responses to the syngeneic protein. To further define the optimal vaccination strategy, we conducted a pilot clinical trial comparing i.m. injection with particle-mediated epidermal delivery (PMED).

EXPERIMENTAL DESIGN

Human leukocyte antigen (HLA)-A*0201(+) disease-free melanoma patients were randomized to the PMED or i.m. arm, receiving eight vaccinations over 4 months. Patients received 4 microg or 2,000 microg per injection, respectively, of mouse gp100 DNA. Peripheral blood mononuclear cells were collected, cultured with gp100 peptides, and analyzed by tetramer and intracellular cytokine staining for responses to HLA-A*0201-restricted gp100 epitopes [gp100(209-217) (ITDQVPFSV) and gp100(280-288) (YLEPGPVTA)].

RESULTS

Twenty-seven patients with stage IIB-IV melanoma were analyzable for immune response. The only common toxicity was grade 1 injection site reaction in nine patients with no intergroup difference, and one dose-limiting toxicity of acute hypersensitivity occurred in a PMED patient with undiagnosed gold allergy. Four of 27 patients produced gp100 tetramer(+)CD8(+) T cells, all carrying the CCR7(lo)CD45RA(lo) effector-memory phenotype. Five of 27 patients generated IFN-gamma(+)CD8(+) T cells, one who was also tetramer-positive. Overall, vaccination induced a response in 30% of patients, which was not significantly associated with study arm or clinical outcome. However, the PMED group showed a trend toward increased IFN-gamma(+)CD8(+) T-cell generation (P = 0.07).

CONCLUSION

A comparable efficacy and safety profile was shown between the i.m. and PMED arms, despite a significantly decreased dose of DNA used for PMED injection.

Novel anti-idiotype antibody therapy for lipooligosaccharide-induced experimental autoimmune neuritis: use relevant to Guillain-Barré syndrome

Campylobacteriosis is a frequent antecedent event in Guillain-Barré syndrome (GBS), inducing high-titer serum antibodies for ganglioside antigens in the peripheral nervous system (PNS). Molecular mimicry between the lipooligosaccharide (LOS) component of Campylobacter jejuni and human peripheral nerve gangliosides is believed to play an important role in the pathogenesis of GBS. Conventional treatment strategies for patients with GBS include plasmapheresis, intravenous immunoglobulin (IVIG), and immunosuppression, which are invasive or relatively ineffective. In this study, we used our animal model of GBS, in which Lewis rats were immunized with GD3-like LOS isolated from C.jejuni. The animals developed anti-GD3 ganglioside antibodies and manifested neuromuscular dysfunction. To develop novel therapeutic strategies, we treated the animals by intraperitoneal administration of an anti-GD3 antiidiotype monoclonal antibody (BEC2) that specifically interacts with the pathogenic antibody. The treated animals had a remarkable reduction of anti-GD3 antibody titers and improvement of motor nerve functions. The results suggest that ganglioside mimics, such as antiidiotype antibodies, may be powerful reagents for therapeutic intervention in GBS by neutralizing specific pathogenic antiganglioside antibodies.

Site and timing of first relapse in stage III melanoma patients: implications for follow-up guidelines

PURPOSE

Stage III melanoma is associated with a high risk of relapse and mortality. Nevertheless, follow-up guidelines have largely been empirical rather than evidence-based.

PATIENTS AND METHODS

Clinical records of stage III patients with no evidence of disease seen at Memorial Sloan-Kettering Cancer Center (MSKCC) between 1992 and 2004, who ultimately relapsed, were reviewed retrospectively to evaluate date of first relapse, time to first relapse, method of first relapse detection, and survival. We also determined overall 5-year relapse-free survival (RFS) of all stage III patients seen at MSKCC during this period.

RESULTS

The overall 5-year RFS for stage IIIA, IIIB, and IIIIC patients was 63%, 32%, and 11%, respectively. Among relapsing patients, 340 had adequate follow-up to be evaluable for all parameters. Site of first relapse was local/in-transit (28%), regional nodal (21%), or systemic (51%). First relapses were detected by the patient or family, physician, or by screening radiologic tests in 47%, 21%, and 32% of patients, respectively. Multivariate analysis revealed that better overall survival was associated with younger age and first relapse being local/in-transit or nodal, asymptomatic, or resectable. For each substage, we estimated site-specific risk of first relapse.

CONCLUSION

Patients detected almost half of first relapses. Our data suggest that routine physical examinations beyond 3 years for stage IIIA, 2 years for stage IIIB, and 1 year for stage IIIC patients and radiologic imaging beyond 3 years for stages IIIA and IIIB and 2 years for stage IIIC patients would be expected to detect few first systemic relapses.

Single-institution experience with ipilimumab in advanced melanoma patients in the compassionate use setting: lymphocyte count after 2 doses correlates with survival

BACKGROUND

Ipilimumab is a monoclonal antibody that antagonizes cytotoxic T lymphocyte antigen-4, a negative regulator of the immune system. The authors report on advanced refractory melanoma patients treated in a compassionate use trial of ipilimumab at the Memorial Sloan-Kettering Cancer Center.

METHODS

Patients with advanced refractory melanoma were treated in a compassionate use trial with ipilimumab 10 mg/kg every 3 weeks for 4 doses. Those with evidence of clinical benefit at Week 24 (complete response [CR], partial response [PR], or stable disease [SD]) then received ipilimumab every 12 weeks.

RESULTS

A total of 53 patients were enrolled, with 51 evaluable. Grade 3/4 immune-related adverse events were noted in 29% of patients, with the most common immune-related adverse events being pruritus (43%), rash (37%), and diarrhea (33%). On the basis of immune-related response criteria, the response rate (CR + PR) was 12% (95% confidence interval [CI], 5%-25%), whereas 29% had SD (95% CI, 18%-44%). The median progression-free survival was 2.6 months (95% CI, 2.3-5.2 months), whereas the median overall survival (OS) was 7.2 months (95% CI, 4.0-13.3 months). Patients with an absolute lymphocyte count (ALC) ≥1000/μL after 2 ipilimumab treatments (Week 7) had a significantly improved clinical benefit rate (51% vs 0%; P = .01) and median OS (11.9 vs 1.4 months; P < .001) compared with those with an ALC <1000/μL.

CONCLUSIONS

The results confirm that ipilimumab is clinically active in patients with advanced refractory melanoma. The ALC after 2 ipilimumab treatments appears to correlate with clinical benefit and OS, and should be prospectively validated. Cancer 2010. © 2010 American Cancer Society.

This description of 51 patients with advanced, treatment-refractory melanoma who were enrolled in a compassionate use trial of ipilimumab at Memorial Sloan-Kettering Cancer Center confirms that ipilimumab is active in this disease setting. In addition, the results suggest that the absolute lymphocyte count after 2 ipilimumab treatments (at Week 7) highly correlates with the rate of clinical benefit at Week 24 and overall survival.

Phase II trial of neoadjuvant temozolomide in resectable melanoma patients

BACKGROUND

We treated melanoma patients with temozolomide (TMZ) in the neoadjuvant setting and collected cryopreserved tumor samples before and after treatment. The primary objective was to determine whether the response proportion was higher than previously reported in widely metastatic patients. A secondary objective was to test the feasibility of obtaining adequate tissue before and after treatment for genetic testing.

MATERIALS AND METHODS

Chemotherapy-naive melanoma patients who were candidates for surgical resection were eligible. TMZ was administered orally at 75 mg/m(2)/day for 6 weeks of every 8-week cycle. Cycles were repeated until complete response (CR), progression, or stable disease (SD) for two cycles.

RESULTS

Of 19 assessable patients, 2 had CRs and 1 had partial response. Four patients had SD; 12 progressed. Tumor O-6-methylguanine-DNA methyltransferase (MGMT) promoter was unmethylated in all nine patients analyzed including from the two CR patients. Pretreatment tumor microarray results were obtained in 16 of 19 patients.

CONCLUSIONS

The response proportion to TMZ in the neoadjuvant setting was 16%, not different than in the metastatic setting. Responses were seen even in tumors with a methylated MGMT promoter. Pretreatment cryopreserved tumor adequate for microarray analysis could be obtained in most, but not all, patients. Post-treatment tumor was unavailable in complete responders.

Counterpoint: The case against adjuvant high-dose interferon-alpha for melanoma patients

High dose interferon-alpha (HD IFN) is approved by the United States Food and Drug Administration for adjuvant treatment of patients with stage III melanoma after complete surgical resection. Despite this, clinicians and patients around the world and in many parts of the US have failed to embrace this treatment option because of the lack of overall survival benefit and minimal other clinical benefits seen in randomized trials, combined with the therapy's substantial toxicity. This article reviews the data from the randomized trials that lead to this conclusion and discuss why arguments often advanced in favor of using HD IFN are not persuasive. New treatment options are needed for adjuvant therapy of melanoma. In the meantime, the data from the randomized trials make it difficult for many clinicians and patients to have enthusiasm for adjuvant HD IFN.

The history and future of chemotherapy for melanoma

Melanoma is considered a chemotherapy-resistant cancer, but in reality there are several chemotherapy drugs with significant single-agent activity. Response rates to combination regimens are reproducibly higher than with standard dacarbazine, but of the randomized trials comparing combination regimens with dacarbazine, none were of sufficient size to detect a realistic effect on survival. Similarly, adjuvant chemotherapy has not had a realistic test in melanoma. Response to chemotherapy is associated reproducibly with better survival rates suggesting that regimens with higher response rates are needed. Recent observations suggest that combining antiangiogenic agents with either dacarbazine or temozolomide can double response rates. These combinations are worthy of further investigation and might serve as a foundation on which to build a combination regimen that improves overall survival in metastatic melanoma patients.

Safety and immunogenicity of a human and mouse gp100 DNA vaccine in a phase I trial of patients with melanoma

A differentiation antigen commonly expressed on melanoma cells, gp100 is the target of infiltrating T cells. We conducted a phase I randomized cross-over trial of melanoma patients with either xenogeneic (mouse) or human gp100 plasmid DNA injected intramuscularly at three dosages (100, 500 or 1,500 microg) every three weeks for three doses. After the first three injections, patients were then immunized three times with gp100 from the other species. Peripheral blood samples were analyzed at various time points following 10-day culture with gp100 peptides using multi-parametric flow cytometry. A total of 19 patients were enrolled, with 18 assessable for immune function and survival. 14 (74%) were male, with a median age of 56 years (range, 20-82). All patients had no evidence of disease; 10 (53%) had stage III disease, 3 each (16%) had stage IIB and IV disease, 2 (11%) had choroidal and 1 (5%) had anal mucosal involvement. With a median follow-up of 30 months, median progression-free survival (PFS) is 44 months. Median survival is not reached. There was no grade 3/4 toxicity; the most common grade 1/2 toxicity was an injection site reaction in 12 patients (63%, all grade 1). Five patients developed CD8+ cells binding gp100(280-288) HLA-A2-restricted tetramer. One patient had an increase in CD8+ IFN-gamma+ cells. This xenogeneic immunization strategy was safe and associated with minimal toxicity. There was also evidence of immune response.

Phase II trial of 17-allylamino-17-demethoxygeldanamycin in patients with metastatic melanoma

PURPOSE

Activation of the mitogen-activated protein kinase (MAPK) pathway and the phosphatidylinositol 3-kinase/AKT pathway seems to be critical for melanoma proliferation. Components of these pathways are client proteins of heat-shock protein 90 (hsp90), suggesting that inhibition of hsp90 could have significant antimelanoma effects. We conducted a phase II trial using the hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) in melanoma patients. The primary end points were clinical responses and whether treatment inhibited MAPK pathway activity.

EXPERIMENTAL DESIGN

Melanoma patients with measurable disease were stratified on the basis of whether or not their tumor harbored a V600E BRAF mutation. The hsp90 inhibitor 17-AAG was administered i.v. once weekly x 6 weeks at 450 mg/m2. Tumor biopsies were obtained pretreatment and 18 to 50 hours after the first dose of 17-AAG, and were snap-frozen.

RESULTS

Fifteen evaluable patients were treated; nine had BRAF mutations and six were wild-type. No objective responses were observed. Western blot analysis of tumor biopsies showed an increase in hsp70 and a decrease in cyclin D1 expression in the posttreatment biopsies but no significant effect on RAF kinases or phospho-extracellular signal-regulated kinase expression. Plasma analyzed by mutant-specific PCR for V600E BRAF showed 86% sensitivity and 67% specificity in predicting tumor DNA sequencing results.

CONCLUSIONS

At this dose and schedule of 17-AAG, the effects of 17-AAG on RAF kinase expression were short-lived, and no objective antimelanoma responses were seen. Future trials in melanoma should focus on a more potent hsp90 inhibitor or a formulation that can be administered chronically for a more prolonged suppression of the MAPK pathway.

Phase I/II study of GM-CSF DNA as an adjuvant for a multipeptide cancer vaccine in patients with advanced melanoma

Granulocyte-macrophage colony-stimulating factor (GM-CSF) enhances immune responses by inducing dendritic cell proliferation, maturation, and migration and B and T lymphocyte expansion and differentiation. The potency of DNA vaccines can be enhanced by the addition of DNA encoding cytokines, acting as molecular adjuvants. We conducted a phase I/II trial of human GM-CSF DNA in conjunction with a multipeptide vaccine (gp100 and tyrosinase) in stage III/IV melanoma patients. Nineteen human leukocyte antigen (HLA)-A*0201(+) patients were treated. Three dose levels were studied: 100, 400, and 800 mcg DNA/injection, administered subcutaneously (SQ) every month with 500 mcg of each peptide. In the dose-ranging study, 3 patients were treated at each dose level. The remaining patients were then treated at the highest dose. Most toxicities were grade 1 injection site reactions. Eight patients (42%) developed CD8+ T-cell responses, defined by a ≥3 SD increase in baseline reactivity to tyrosinase or gp100 peptide in tetramer or intracellular cytokine staining assays. There was no relationship between dose and T-cell response. Responding T cells had an effector memory cell phenotype. Polyfunctional T cells were also demonstrated. At a median of 31 months follow-up, median survival has not been reached. Human GM-CSF DNA was found to be a safe adjuvant.

Antibody response to GD3 ganglioside is independent of NKT cells

BACKGROUND

NKT cells recognize glycolipids presented by CD1d on antigen-presenting cells (APC) and have been largely characterized by their ability to be activated by alpha-galactosylceramide, a glycolipid not expressed on mammalian cells. We have shown previously that GD3 can be cross-presented by CD1d to NKT cells and is the first tumor-derived glycolipid recognized by NKT cells. But the ability of NKT cells to modulate B-cell responses to tumor glycolipids that are themselves recognized by NKT cells has not been explored.

METHODS

We tested whether NKT cells are required for antibody (Ab) responses to GD3. We immunized wild-type mice, mice deficient in invariant chain NKT cells (iNKT cells) and mice deficient in total NKT cells against GD3. Ab titer against GD3 was measured by ELISA.

RESULTS

We found the IgM and IgG responses against GD3 were similar among the three strains of mice, including the IgG isotypes induced. Pre-expanded NKT cells to GD3 did not affect the anti-GD3 Ab response.

DISCUSSION

We conclude that Ab responses to GD3 are independent of NKT cells and that strategies to manipulate NKT cells in vivo are not likely to enhance the anti-GD3 Ab response induced by vaccines.

Phase II study of extended-dose temozolomide in patients with melanoma

PURPOSE

We conducted a phase II trial of extended-dose temozolomide (TMZ) in patients with melanoma to test the hypothesis that the approximately 30% response rate observed in patients treated with extended-dose TMZ with antiangiogenic agents was caused by TMZ alone. We hypothesized that expression of methylguanine methyltransferase (MGMT) in the tumor would correlate with drug resistance to TMZ.

PATIENTS AND METHODS

Patients with stage IV or unresectable stage III melanoma were treated with TMZ 75 mg/m(2)/d for 6 weeks followed by a 2-week rest period. Cycles were repeated until progression. Patients were stratified by M1c disease or not. The primary end point was objective response proportion. MGMT expression was assessed by methylation-specific pyrosequencing of the promoter and by immunohistochemistry.

RESULTS

Forty-nine patients (25 with M1c disease) were assessable. Three patients (12.5%) in each cohort experienced partial responses; there were no complete responses. Ten patients (21%) had stable disease lasting more than 24 weeks. Median time to progression was 3.3 months. Median survival was 10.1 months; survival was similar in the two cohorts. The estimated 18-month survival was 27%. There was no correlation between response and either immunohistochemistry staining for MGMT or for MGMT promoter methylation. Seventy-five percent of patients developed CD4(+) lymphopenia after three cycles.

CONCLUSION

Extended-dose TMZ therapy did not result in a 30% responses rate, which has been observed using extended-dose TMZ with antiangiogenic agents. Response did not correlate with MGMT expression or promoter methylation as a continuous variable, suggesting that other resistance mechanisms are important.

Fine specificity of natural killer T cells against GD3 ganglioside and identification of GM3 as an inhibitory natural killer T-cell ligand

GD3, a ganglioside expressed on melanoma, is the only tumour-associated glycolipid described to date that can induce a CD1d-restricted natural killer T (NKT)-cell response. We analysed the fine specificity of GD3-reactive NKT cells and discovered that immunization with GD3 induced two populations of GD3-reactive NKT cells. One population was CD4+ CD8- and was specific for GD3; the other population was CD4- CD8- and cross-reacted with GM3 in a CD1d-restricted manner, but did not cross-react with GM2, GD2, or lactosylceramide. This indicated that the T-cell receptors reacting with GD3 recognize glucose-galactose linked to at least one N-acetyl-neuraminic acid but will not accommodate a terminal N-acetylgalactosamine. Immunization with GM2, GM3, GD2, or lactosylceramide did not induce an NKT-cell response. Coimmunization of GM3-loaded antigen-presenting cells (APCs) with GD3-loaded APCs suppressed the NKT-cell response to GD3 in a CD1d-restricted manner. This suppressive effect was specific for GM3 and was a local effect lasting 2-4 days. In vitro, GM3-loaded APCs also suppressed the interleukin-4 response, but not the interferon-gamma response, of NKT cells to alpha-galactosylceramide. However, there was no effect on the T helper type 2 responses of conventional T cells. We found that this suppression was not mediated by soluble factors. We hypothesize that GM3 induces changes to the APC that lead to suppression of T helper type 2-like NKT-cell responses.

Adjuvant therapy of melanoma

PURPOSE

The purpose of this article was to review the current state of knowledge regarding the efficacy of adjuvant therapy for melanoma.

PATIENTS AND METHODS

We reviewed the published literature, focusing on randomized clinical trials.

RESULTS

There have been no meaningful trials addressing adjuvant chemotherapy in melanoma because all trials have been underpowered. Adjuvant interferon-alpha has been tested both at high dose and at lower doses. None of the trials have shown a reproducible benefit in survival, although the high-dose trials and some of the low-dose trials have shown improvement in time to relapse. These experiences raise the question of whether chronic administration is more important than dose. An adjuvant pegylated interferon-alpha trial using a 5-year treatment period is currently under investigation. At least 7 randomized adjuvant vaccine trials have been published, but none have shown a beneficial effect on relapse-free or overall survival except in subset analyses.

CONCLUSIONS

To date, no adjuvant therapy has resulted in improved overall survival. To be attractive as an adjuvant therapy, experience from other tumor types indicates that a chemotherapy regimen should have a response rate of at least 20% in metastatic melanoma. Currently, biochemotherapy is being tested as an adjuvant treatment but other, less toxic, regimens should be sought. Once such a regimen with acceptable toxicity is identified, it would be reasonable to test it as an adjuvant therapy in a properly powered randomized trial. High-dose interferon-alpha for 1 year remains the only U.S. Food and Drug Administration-approved adjuvant therapy for melanoma, but long-term chronic dosing of interferon-alpha may prove more effective than short-term dose schedules. Development of melanoma vaccines remains an appealing and important goal. New technologies and understanding of the immune response against melanoma are leading to novel vaccine strategies designed to break immunologic tolerance against melanoma.