Androgen receptor blockade promotes response to BRAF/MEK-targeted therapy

9523

Background: Treatment with BRAF+/-MEK inhibition (BRAF+/-MEKi) has revolutionized treatment in melanoma and other cancers, but resistance is common and innovative treatment strategies are needed. Sexual dimorphism in response to BRAF+/-MEKi have been noted, but mechanisms behind this are poorly understood and hormonal modulation has not been well-studied in this setting. Methods: We examined outcomes by sex in five clinical cohorts of patients (pts) (total n = 792, 362 female, 430 male) with BRAF-mutated melanoma who were treated with BRAF/MEKi in either the neoadjuvant or metastatic setting. Rates of major pathologic response (MPR), clinical benefit (CB), progression free survival (PFS) relapse-free survival (RFS) and overall survival (OS) were assessed. Translational research studies were performed on available pre- and on-treatment tumor samples (n = 27 pts) including RNA sequencing and profiling androgen receptor (AR) expression. Parallel studies were performed in preclinical models to assess the effect of sex and AR modulation on response to BRAF+/-MEKi. Results: In this study, improved rates of MPR, CB, PFS and OS were observed in female vs male pts. Specifically, female patients treated with neoadjuvant BRAF+MEKi showed significantly higher rates of MPR (66% v. 14%, p = 0.001), and improved RFS (64% versus 32% at 2 years, p = 0.021) vs male pts in the neoadjuvant setting (n = 51). These findings were not observed in a 2nd smaller trial of pts (n = 35), but were validated in a cohort of pts with unresectable metastatic melanoma treated with BRAF+MEKi (n = 69), with significantly higher rates of CB (80% v. 68%, p = 0.022) and PFS (12 v. 7 months, p = 0.003) in female vs male pts. Data from several published trials was analyzed (COMBI-D and METRIC trials), demonstrating improved PFS/OS at 2 years in female vs male pts treated with combined BRAF/MEKi (n = 211; p = 0.03 and, p = 0.04) and in female vs male pts treated with MEKi monotherapy (n = 206; p = 0.04 and p = 0.002), but not in female vs male pts treated with BRAFi monotherapy (n = 211; p = 0.21 and 0.095). Significantly higher expression AR expression was observed in available on- vs pre-treatment samples from male pts (p = 0.01), suggesting that treatment with BRAF/MEKi may induce AR expression in tumors. Findings were recapitulated in several preclinical models, and treatment with pharmacologic inhibitors of AR signaling (enzalutamide) in combination with BRAF/MEKi was associated with significantly enhanced anti-tumor activity in both male and female mice (p = 0.003 and p < 0.0001). Conversely, systemic treatment with testosterone was associated with significantly impaired tumor control in male and female mice (p = 0.021 and < 0.001). Conclusions: These data suggest that AR blockade may promote BRAF/MEKi response in melanoma, warranting further investigation in clinical trials. The impact of AR signaling, and modulation should be studied in MAPK-targeted therapy across other cancer types.

Adjuvant dabrafenib plus trametinib (D + T) versus placebo in patients with resected stage III BRAFV600-mutant melanoma: Updated 5-year distant metastases-free survival (DMFS) analysis of COMBI-AD

9563

Background: DMFS is an important endpoint for patients with stage III cutaneous melanoma, as delaying or preventing systemic disease is associated with improved clinical and patient-reported outcomes. Prior results from the phase 3 COMBI-AD trial (NCT01682083) showed 5-year DMFS rates of 65% with adjuvant D + T vs 54% with placebo (PBO; hazard ratio [HR] = 0.55; 95% CI: 0.44-0.70). An analysis of DMFS by AJCC-7 stages IIIA-C suggested a similar benefit of D + T vs PBO regardless of stage (Dummer R et al. N Engl J Med. 2020). Here, we report 5-year DMFS rates by AJCC-8 stages IIIA-D, other prognostic subgroups, and results of a regression tree analysis with DMFS. Methods: Patients with resected AJCC-7 stage III BRAFV600E/K-mutant melanoma were randomized to either D (150 mg twice daily) + T (2 mg once daily) or 2 matched PBOs for 12 months. Primary endpoint was relapse-free survival (RFS); DMFS was a secondary endpoint. Kaplan-Meier survival analyses were performed to assess the long-term benefits for DMFS rates with D + T vs PBO. The regression tree analysis (data cutoff: 5 years) for all patients (N = 870) evaluated potential prognostic/predictive factors of long-term DMFS including baseline age, sex, region, BRAF mutation type, body mass index, lactate dehydrogenase levels, ECOG, T and N categories, histology, primary tumor ulceration, treatment type, number of lymph nodes with metastases, tumor mutational burden, and interferon-gamma gene expression signature (IFN-γ GES). Results: At 5 years, DMFS rates were higher for patients with AJCC-8 stages IIIB-D disease receiving adjuvant D + T vs PBO (table). Five-year DMFS rates also favored D + T vs PBO in subgroups of patients with microscopic or macroscopic lymph node involvement (table) and those with or without primary tumor ulceration and/or in-transit metastases. A regression tree revealed T and N stage, treatment type, and IFN-γ GES as important variables defining 5-year DMFS subgroups. Conclusions: In this retrospective analysis, adjuvant D + T provided long-term DMFS benefit vs PBO in stage IIIB-D patients with resected BRAFV600E/K-mutant melanoma. Key clinical and patient factors impacting DMFS were similar to prior RFS findings (ESMO 2021; Robert C et al. Ann Oncol. 2021) and included T and N stage, treatment type, and IFN-γ GES. These results further validate the robust long-term clinical benefit of adjuvant D + T for patients with melanoma. Clinical trial information: NCT01682083. [Table: see text]

Pyrexia-related outcomes upon application of an adapted pyrexia management algorithm in patients (pts) with BRAF V600: Mutant unresectable or metastatic melanoma treated with dabrafenib plus trametinib (DabTram) in the COMBI-i trial

9560

Background: First-line DabTram has shown long-term efficacy in pts with BRAF V600–mutant unresectable or metastatic melanoma in the Phase III COMBI-d and COMBI-v trials. Data from the Phase III COMBI-i trial comparing spartalizumab plus DabTram vs placebo plus DabTram (pbo-DabTram) demonstrated efficacy in the pbo-DabTram arm, consistent with historical data. Pyrexia (single preferred term [PT]) is the most common adverse event (AE) reported with DabTram (pooled COMBI-d [data cutoff: Jan 12, 2015] and COMBI-v [data cutoff: Apr 17, 2014]: any grade, 54.2%; grade ≥ 3, 5.4%; serious pyrexia AEs leading to hospitalization, 11.8%). A new pyrexia management algorithm was implemented in the COMBI-i trial to improve pyrexia-related outcomes. We report pyrexia-related outcomes in pts treated with pbo-DabTram in the control arm of COMBI-i part 3. Methods: COMBI-i (NCT02967692) part 3 is a double-blind, Phase III trial in which pts with previously untreated BRAF V600–mutant unresectable or metastatic melanoma were randomized 1:1 to receive spartalizumab (400 mg intravenously every 4 weeks) plus Dab (150 mg orally twice daily) and Tram (2 mg orally once daily) vs pbo-DabTram. In the adapted pyrexia management algorithm, both Dab and Tram are interrupted promptly at the first symptom of pyrexia or its associated prodrome (ie, chills, rigors, night sweats, or influenza-like symptoms). Treatment at the same dose level is restarted upon the improvement of symptoms if pts are symptom free for ≥ 24 hours. Pyrexia incidence rates presented are for the single PT of pyrexia. Results: At data cutoff (July 1, 2020), median follow-up was 27.2 mo for all pts enrolled in COMBI-i part 3 (N = 532). In the DabTram control arm, 52.7% (139/264) and 3.0% (8/264) of pts had any-grade and grade ≥ 3 pyrexia, respectively. Serious pyrexia AEs were reported in 6.1% (16/264), which led to hospitalization in 5.3% (14/264). Pyrexia led to dose interruption of both Dab and Tram in 39.0% (103/264), with 1.5% (4/264) permanently discontinuing both agents. Median relative dose intensity was 97.8% for Dab and 97.7% for Tram. Conclusions: Pyrexia-related outcomes, including grade ≥ 3 pyrexia (3.0% vs 5.4%) and serious pyrexia AEs leading to hospitalization (5.3% vs 11.8%), were improved in pts treated with DabTram in COMBI-i part 3 compared with historical data from COMBI-d/v. The adapted algorithm offers a simplified approach for managing pyrexia, thereby reducing the incidence of severe pyrexia while maintaining consistent efficacy with DabTram. Clinical trial information: NCT02967692.

Improved pyrexia-related outcomes associated with an adapted pyrexia adverse event (AE) management algorithm in patients (pts) treated with adjuvant dabrafenib + trametinib (dab + tram): Primary results of COMBI-APlus

9525

Background: The long-term benefit of adjuvant dab + tram in pts with resected stage III BRAF V600E/K–mutant melanoma was demonstrated in COMBI-AD where AEs led to permanent discontinuation of dab + tram in 26% of pts, most often due to pyrexia (9%). The COMBI-APlus trial (NCT03551626) is designed to evaluate whether an adapted pyrexia management algorithm could reduce high-grade pyrexia and other pyrexia-related adverse outcomes, such as treatment cessation and hospitalization. Methods: COMBI-APlus is an open-label, Phase IIIb trial evaluating an adapted pyrexia management algorithm in pts with high-risk resected stage III BRAF V600E/K–mutant melanoma treated with 12 mo of adjuvant dab + tram. In the adapted algorithm, both dab and tram were interrupted promptly at the onset of pyrexia (temperature ≥ 38°C). In the event of suspected recurrent pyrexia, treatment may be interrupted in the presence of pyrexia syndrome (ie, chills, rigors, night sweats, or influenza-like symptoms without temperature ≥ 38°C) at investigator discretion. Treatment with dab + tram was restarted at the same dose level once pts were symptom free for ≥ 24 hours. The primary endpoint is the composite rate of grade 3/4 pyrexia, hospitalization due to pyrexia, or permanent discontinuation due to pyrexia vs a historical control from COMBI-AD (20%; 95% CI, 16.3%-24.1%). Secondary endpoints include relapse-free survival (RFS) and safety. Results: A total of 552 pts were enrolled. At the data cutoff (5 Oct 2020), all pts had completed 12 mo of treatment; median duration of follow-up was 18.4 mo. COMBI-APlus met its primary endpoint of significant improvement in composite rate of pyrexia. The composite rate was 8.0% (95% CI, 5.9%-10.6%), with rates of 3.8% for grade 3/4 pyrexia, 4.3% for hospitalization due to pyrexia, and 2.4% for discontinuation due to pyrexia. The estimated 12-mo RFS rate was 91.8% (95% CI, 89.0%-93.9%). The most common AEs (≥ 20%) were pyrexia (67.8%), headache (31.7%), blood creatine phosphokinase increase (27.9%), diarrhoea (27.0%), chills (26.4%), fatigue (25.7%), asthenia (23.6%), nausea (23.4%), rash (21.4%), and arthralgia (21.0%). AEs of any type led to permanent dab + tram discontinuation in 14.7% of pts. Conclusions: This primary analysis suggests the new adapted pyrexia management algorithm is effective in reducing grade 3/4 pyrexia, pyrexia-related hospitalization, and treatment discontinuation in pts receiving adjuvant dab + tram. The early efficacy appears consistent with that observed in COMBI-AD. The growing experience of oncologists in managing pyrexia with this simple algorithm may reduce the need for hospitalization or visits to a healthcare provider, which is highly desirable during the current COVID-19 pandemic. Thus, more pts can remain on treatment and derive benefit. Clinical trial information: NCT03551626.

Lapatinib access into normal brain and brain metastases in patients with Her-2 overexpressing breast cancer

BACKGROUND

Brain metastases are common in human epidermal growth factor receptor (Her)-2-positive breast cancer. Drug access to brain metastases and normal brain is key to management of cranial disease. In this study, positron emission tomography (PET) scanning after administration of radiolabelled lapatinib was used to obtain direct evidence of cranial drug access.

METHODS

Patients with Her-2+ metastatic breast cancer either with at least one 1-cm diameter brain metastasis or without brain metastases underwent dynamic carbon-11 radiolabelled lapatinib ([(11)C]lapatinib)-PET. Less than 20 μg of [(11)C]lapatinib was administered before and after 8 days of oral lapatinib (1,500 mg once daily). Radial arterial blood sampling was performed throughout the 90-min scan. The contribution of blood volume activity to the tissue signal was excluded to calculate lapatinib uptake in normal brain and metastases. Partitioning of radioactivity between plasma and tissue (V T) was calculated and the tissue concentration of lapatinib derived. Plasma lapatinib levels were measured and adverse events noted.

RESULTS

Six patients (three with brain metastases) were recruited. About 80% plasma radioactivity corresponded to intact [(11)C]lapatinib after 60 min. PET signal in the brain corresponded to circulating radioactivity levels, with no [(11)C]lapatinib uptake observed in normal brain tissue. In contrast, radioactivity uptake in cranial metastases was significantly higher (p = 0.002) than that could be accounted by circulating radioactivity levels, consistent with [(11)C]lapatinib uptake in brain metastases. There was no difference in lapatinib uptake between the baseline and day 8 scans, suggesting no effect of increased drug access by inhibition of the drug efflux proteins by therapeutic doses of lapatinib.

CONCLUSIONS

Increased lapatinib uptake was observed in brain metastases but not in normal brain.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01290354.

Optimally tolerated dose of lapatinib in combination with docetaxel plus trastuzumab in first-line treatment of HER2-positive metastatic breast cancer

BACKGROUND

This phase IB, open-label, dose-escalation study evaluated the safety, tolerability, and optimally tolerated regimen (OTR) of lapatinib in combination with docetaxel and trastuzumab in patients with previously untreated stage IV metastatic breast cancer (MBC) tumors overexpressing human epidermal growth factor receptor 2 (HER2).

PATIENTS AND METHODS

Evaluated dose regimens included lapatinib (500-1500 mg/day), docetaxel (triweekly; 60-100 mg/m&sup2;), and trastuzumab (weekly; 2 mg/kg fixed dose); prophylactic granulocyte colony-stimulating factor was included with regimens with ≥750 mg/day lapatinib. End points included OTR and safety/tolerability (primary), overall response rate (ORR), and pharmacokinetics (secondary).

RESULTS

None of the patients (N = 53) experienced dose-limiting toxic effects (DLTs) at the highest dose level; thus, the OTR of lapatinib with 100 mg/m(2) docetaxel was not determined. Common adverse events included diarrhea, nausea, alopecia, fatigue, and rash; grade 3/4 (≥2 patients) were neutropenia, diarrhea, leukopenia, peripheral neuropathy, and rash. Seven patients had DLTs (cycle 1). In 45 patients with measurable disease confirmed by bone scan, investigator-assessed ORR was 31%; without bone scan, confirmation was 64%; 8 patients without measurable disease were evaluated as stable. Lapatinib/docetaxel plasma concentrations were positively associated with complete response.

CONCLUSIONS

Lapatinib/docetaxel/trastuzumab is a feasible and well-tolerated treatment of untreated HER2-positive stage IV MBC. Two lapatinib/docetaxel OTR doses were recommended (1250 mg/75 mg/m&sup2;; 1000 mg/100 mg/m&sup2;).

CLINICAL TRIAL NUMBER

NCT00251433.

OT1-02-09: A Phase II Randomized Trial of Lapatinib with Either Vinorelbine or Capecitabine as First- and Second-Line Therapy for HER2−Overexpressing Metastatic Breast Cancer

Background: Lapatinib, a dual kinase inhibitor of epidermal growth factor receptor (EGFR) and the human epidermal growth factor receptor-2 (HER2/ErbB2), is approved for the treatment of HER2−overexpressing (HER2+) metastatic breast cancer (MBC) in combination with capecitabine following progression after trastuzumab, anthracyclines, and taxanes. Vinorelbine is an important chemotherapy option in MBC, and multiple phase II trials in combination with trastuzumab have been conducted.

Methods: This randomized, open-label, multicenter, phase II study (VITAL, LAP112620, NCT01013740) is evaluating the efficacy and safety of lapatinib with either vinorelbine or capecitabine in women with HER2+ MBC. A total of 105 stage IV breast cancer patients with disease progression who have received ≤1 chemotherapy regimen in the metastatic setting with an ECOG performance status of ≤1 are randomized 2:1 to either: lapatinib 1250 mg orally once daily (QD) continuously plus vinorelbine 20 mg/m2 intravenously on days 1 and 8 every third week; or lapatinib 1250 mg orally QD continuously plus capecitabine 2000 mg/m2/d orally in 2 doses 12 hours apart on days 1 to 14 every third week. Following progression in the randomized phase, patients will be given the option to cross over to the other arm. The primary endpoint is progression-free survival and will be analyzed with a descriptive intent since the study is not powered to detect differences between treatment arms. Secondary endpoints include overall response rate, overall survival, duration of response, time to response, and clinical benefit rate.

The study is currently recruiting in 8 countries in Europe (Bulgaria, France, Germany, Greece, Italy, Poland, Serbia, Spain) and 2 in Latin America (Chile, Mexico).

Funding Source: GlaxoSmithKline

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT1-02-09.

OT2-05-01: An Open-Label Positron Emission Tomography Study To Investigate and Quantify Brain and Tumor Penetration of Carbon-11-Labeled Lapatinib in Patients with HER2−Overexpressing Advanced or Metastatic Breast Cancer

Background: Patients with HER2−overexpressing (HER2+) breast cancer tend to develop visceral metastases. About a third will develop brain metastases in the course of their disease. Several anticancer agents including trastuzumab are not believed to readily cross the blood-brain barrier (BBB); therefore, central nervous system (CNS) disease progression is emerging as an important clinical problem in this patient population. Although preclinical data indicate that lapatinib brain concentrations are low in healthy animals, probably due to the BBB efflux transporters, observations from clinical studies suggest lapatinib treatment might be associated with reduced CNS tumor growth. One hypothesis is that disruption of the BBB by tumors circumvents the usual protective function of transporters. Alternatively, inhibition of efflux transporters by lapatinib enhances its own accumulation with repeat dosing. The role of lapatinib in prevention of brain metastases is currently being explored in a phase III trial, EGF 111438 (CEREBEL).

Methods: To directly assess if lapatinib penetrates the brain and brain metastases, an open-label non-randomized study using carbon-11-labeled [11C] lapatinib is enrolling patients with HER2+ metastatic breast cancer. A minimum of 10 patients with an ECOG of &lt;3 are grouped into 2 cohorts: with at least one 1-cm diameter brain metastasis or without brain metastases. Two positron emission tomography (PET) scans will be performed in each patient following intravenous administration of a microdose of [11C] lapatinib: in lapatinib-naïve patients and at steady-state lapatinib, after treatment with unlabelled oral lapatinib 1500 mg once daily for 8 days. [11C] lapatinib time-activity curves will be generated for normal brain and brain metastases, the PET volume of distribution in the brain calculated and penetration of [11C] lapatinib into the brain quantified. Analysis of brain PET data is explorative as [11C] lapatinib is a new tracer. Therefore, this study investigates both the difference in lapatinib brain penetration between patients with and without brain metastases, as well as the effect of low and high concentrations of lapatinib on the BBB efflux system.

The study is currently recruiting in one center in the United Kingdom.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT2-05-01.

Amplification of epidermal growth factor receptor gene in renal cell carcinoma

Expression of epidermal growth factor receptor (EGFR) may be of prognostic value in renal cell cancer (RCC). Gene amplification of EGFR was investigated in a cohort of 315 patients with advanced RCC from a previously reported randomised study. Using fluorescent in situ hybridisation, only 2 patients (0.6%) had gene amplification; therefore gene amplification is of no prognostic value in RCC.

cDNA cloning of a third human C2-domain-containing class II phosphoinositide 3-kinase, PI3K-C2gamma, and chromosomal assignment of this gene (PIK3C2G) to 12p12

Phosphoinositide (PI) 3-kinases have been shown to have critical roles in signaling pathways that regulate proliferation, oncogenic transformation, cell survival, cell migration, and intracellular protein trafficking. We have previously used reverse-transcription polymerase chain reaction methods to identify novel PI 3-kinase isoforms in normal human breast and in lymph nodes containing metastatic breast cancer. Here we report the cDNA cloning of a Class II PI 3-kinase found in normal breast tissue. This gene (PIK3C2G) encodes the third distinct protein of the human Class II PI 3-kinase family, PI3K-C2gamma. PIK3C2G was mapped to chromosome 12 at 12p12 by fluorescence in situ hybridization.