Adjuvant enzalutamide for the treatment of early-stage androgen-receptor positive, triple-negative breast cancer: a feasibility study

PURPOSE

Chemotherapy with or without immunotherapy remains the mainstay of treatment for triple-negative breast cancer (TNBC). A subset of TNBCs express the androgen receptor (AR), representing a potential new therapeutic target. This study assessed the feasibility of adjuvant enzalutamide, an AR antagonist, in early-stage, AR-positive (AR +) TNBC.

METHODS

This study was a single-arm, open-label, multicenter trial in which patients with stage I-III, AR ≥ 1% TNBC who had completed standard-of-care therapy were treated with enzalutamide 160 mg/day orally for 1 year. The primary objective of this study was to evaluate the feasibility of 1 year of adjuvant enzalutamide, defined as the treatment discontinuation rate of enzalutamide due to toxicity, withdrawal of consent, or other events related to tolerability. Secondary endpoints included disease-free survival (DFS), overall survival (OS), safety, and genomic features of recurrent tumors.

RESULTS

Fifty patients were enrolled in this study. Thirty-five patients completed 1 year of therapy, thereby meeting the prespecified trial endpoint for feasibility. Thirty-two patients elected to continue with an optional second year of treatment. Grade ≥ 3 treatment-related adverse events were uncommon. The 1-year, 2-year, and 3-year DFS were 94%, 92% , and 80%, respectively. Median OS has not been reached.

CONCLUSION

This clinical trial demonstrates that adjuvant enzalutamide is a feasible and well-tolerated regimen in patients with an early-stage AR + TNBC. Randomized trials in the metastatic setting may inform patient selection through biomarker development; longer follow-up is needed to determine the effect of anti-androgens on DFS and OS in this patient population.

Abstract P1-14-03: Adjuvant enzalutamide for the treatment of early-stage androgen-receptor positive, triple negative breast cancer: A feasibility study

Background: Chemotherapy remains the mainstay of treatment for early-stage triple negative breast cancer (TNBC), yet targetable drivers of interest are under investigation. A subset of TNBCs express the androgen receptor (AR) and exhibit androgen-dependent growth. The AR-antagonist enzalutamide (ENZA) has shown activity in patients with metastatic AR+ TNBC. In this study, the feasibility of adjuvant ENZA in early-stage, AR+ TNBC was assessed (NCT02750358). As reported previously, this study met its primary endpoint of feasibility (Traina et al., ASCO 2019). Here we report secondary survival endpoints. Methods: In this single-arm, open-label, multi-center trial, patients with stage I-III, AR≥1% TNBC (ER/PR <1%, HER2 negative) who had completed standard of care therapy were treated with ENZA 160 mg/day orally for 1 year. Patients who completed 1 year had an option to remain on adjuvant ENZA for another year. Toxicity was graded using National Cancer Institute Common Toxicity Criteria (NCI CTCAE) v4. The primary endpoint of this study was to evaluate feasibility of adjuvant ENZA, defined as the discontinuation rate due to toxicity, withdrawal of consent, other events related to tolerability or patient preference. The study was designed to discriminate between feasibility rates of 50% and 70% and was considered feasible if ≥29 out of 46 patients received ENZA for one year without discontinuation. Secondary endpoints included DFS, OS, safety, patient reported outcomes and correlative science. Patients who had disease progression (PD) during year 1 of ENZA without treatment discontinuation due to the above reasons were not included in the primary feasibility analysis but were included in secondary endpoint analyses for survival. Results: 50 patients enrolled on study from 05/2016 - 06/2018. The median age was 58 years (range 34-81 years); 8% had a germline BRCA1/2 (n=3) or PALB2 (n=1) mutation. 38% had stage I disease at diagnosis, 48% stage II and 14% stage III. 74% had grade 3 tumors. 94% of all patients received prior systemic chemotherapy, 81% of whom received prior anthracycline-taxane. 38% (n=19) were treated with prior neoadjuvant chemotherapy and 32% of those patients (n=6) achieved a pCR. Of those who did not achieve a pCR, 69% received adjuvant capecitabine. 47 patients were evaluable for the study endpoint and 35 patients completed 1 year of ENZA thereby meeting the prespecified trial endpoint for feasibility. 32 patients elected to continue into a second year of treatment. After a median follow-up of 140 weeks (range 4 - 236 weeks), 8 patients had a DFS event: 7 TNBC recurrences and 1 new primary breast cancer. The 1-year DFS was 94% (95% CI: 87 - 100%), 2-year DFS was 92% (95% CI: 84 - 99.8%) and the 3-year DFS was 80% (95% CI: 67 - 94%). The median DFS and OS have not yet been reached. Two patients died of TNBC recurrence after 55 and 59 weeks. There were no new or unexpected toxicities observed at study completion. Conclusion: This single-arm trial previously met its primary endpoint of feasibility in patients with early-stage AR+ TNBC. In this relatively high-risk, albeit highly selected patient population, the 3-year DFS measured 80% (95% CI: 67 - 94%) with an adjuvant endocrine therapy approach. Efforts to determine the optimal biomarker for AR+ TNBC are ongoing, so that patients most likely to respond to AR-antagonists in both the early and metastatic setting may be identified. Biomarker data from this study including PD-L1 status and tumor sequencing will be reported at the time of presentation.Funding and drug support for this study was provided by Astellas Pharma Global Development Inc./Pfizer Inc.

Citation Format: Elaine M Walsh, Ayca Gucalp, Sujata Patil, Marcia Edelweiss, Dara S Ross, Pedram Razavi, Shanu Modi, Neil M Iyengar, Rachel Sanford, Tiffany Troso-Sandoval, Mila Gorsky, Jackie Bromberg, Pamela Drullinsky, Diana Lake, Serena Wong, Patricia DeFusco, Nicholas Lamparella, Ranja Gupta, Tasmila Tabassum, Leigh Ann Boyle, Artavazd Arumov, Tiffany A Traina. Adjuvant enzalutamide for the treatment of early-stage androgen-receptor positive, triple negative breast cancer: A feasibility study [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-14-03.

The C-Terminal Intact Forms of Periostin (iPTN) Are Surrogate Markers for Osteolytic Lesions in Experimental Breast Cancer Bone Metastasis

Periostin is an extracellular matrix protein that actively contributes to tumor progression and metastasis. Here, we hypothesized that it could be a marker of bone metastasis formation. To address this question, we used two polyclonal antibodies directed against the whole molecule or its C-terminal domain to explore the expression of intact and truncated forms of periostin in the serum and tissues (lung, heart, bone) of wild-type and periostin-deficient mice. In normal bones, periostin was expressed in the periosteum and specific periostin proteolytic fragments were found in bones, but not in soft tissues. In animals bearing osteolytic lesions caused by 4T1 cells, C-terminal intact periostin (iPTN) expression disappeared at the invasive front of skeletal tumors where bone-resorbing osteoclasts were present. In vitro, we found that periostin was a substrate for osteoclast-derived cathepsin K, generating proteolytic fragments that were not recognized by anti-periostin antibodies directed against iPTN. In vivo, using an in-house sandwich immunoassay aimed at detecting iPTN only, we observed a noticeable reduction of serum periostin levels (- 26%; P < 0.002) in animals bearing osteolytic lesions caused by 4T1 cells. On the contrary, this decrease was not observed in women with breast cancer and bone metastases when periostin was measured with a human assay detecting total periostin. Collectively, these data showed that mouse periostin was degraded at the bone metastatic sites, potentially by cathepsin K, and that the specific measurement of iPTN in serum should assist in detecting bone metastasis formation in breast cancer.

Rituximab-Induced Splenic Rupture and Cytokine Release

Patient: Female, 55

Final Diagnosis: Mantle cell lymphoma

Symptoms: Cytokine release syndrome • hypoglycemia • hypotension • splenic rupture • splenomegaly • vision loss

Medication: —

Clinical Procedure: Case Report

Specialty: Oncology

Fatal malignant metastastic epithelioid angiomyolipoma presenting in a young woman: case report and review of the literature

Epithelioid angiomyolipomas (EAMLs) are rare mesenchymal tumors whose malignant variant is extremely uncommon and highly aggressive. Treatment strategies include chemo radiation, transcatheter arterial embolization and surgical resection, which has remained the mainstay treatment. Targeted therapies including mammalian target of rapamycin (mTOR) inhibitors such as Temsirolimus may offer some hope for progressive malignant EAMLs that are not amenable to other treatment modalities. We report a fatal case in a young female who presented with rapidly progressive metastatic EAML that did not respond to mTOR therapy. The literature has shown reduction in tumor burden with the use of mTOR inhibitors, but unfortunately due to the rarity of malignant EAML, a meaningful approach to treatment remains challenging.

Abstract 3625: A multiplexed marker-based algorithm for diagnosis of carcinoma of unknown primary (CUP) using circulating tumor cells

Metastasis is responsible for the majority of cancer-related deaths. A limiting step in metastasis is access to circulation, thus circulating tumor cells (CTCs) should be present in all patients with metastatic tumors, which may have both diagnostic and prognostic value. Accounting for only 2-3%, carcinoma of unknown primary (CUP) presents a challenge for clinicians in diagnosis and therapy. Tissue biopsy is the standard for diagnosis but there is need for improved methodology including a non-invasive blood test that may rely on CTC analysis. We have been developing a post-Veridex CTC analysis method using multiplexed Q-dot conjugated antibodies with the goal of detection of multiple markers in each single cell within a CTC population to aid in CUP diagnosis including tissue of origin. We have developed an immunofluorescence (IF) protocol with a minimal set of markers to predict the primary sites and provide prognostic information for common metastatic tumors: melanoma, lung, colorectal, upper gastrointestinal organs, and breast or prostate cancer. Two kits are available to isolate CTCs through Veridex CellSearch: melanoma kit (using melanoma antigen), and epithelial or carcinoma kit (using EpCam). A patient's blood is initially tested with both kits, and positive CTCs from the melanoma kit supports a diagnosis of melanoma, whereas positive CTCs from the epithelial kit supports carcinoma. For carcinomas, we use cytokeratin 7 (CK7), cytokeratin 20 (CK20), thyroid transcription factor 1 (TTF-1), estrogen receptor (ER) or prostate-specific antigen (PSA) as the minimal set of markers. IF has been optimized in cultured tumor cells, first with individual antibodies, then quantum dots (Q-dot) conjugated multiplex quadra-antibody set. We evaluated antibodies by IF specific to these 5 markers in lung, breast, colorectal, and prostate cancer cell lines. The CK7 and ER antibodies conjugated to Qdot 605 and 705 respectively demonstrated expression in the appropriate cell lines. CK7-Qdot 605 and ER-Qdot 705 expression in cells that were recovered after being spiked into normal blood samples and isolated by the Veridex CellSearch system was similar to that observed with unconjugated antibodies. Our data show that it is feasible to detect expression using Qdot-labeled multiplexed antibodies on tumor cells isolated from blood by Veridex CellSearch system. Successful application of this protocol to CTCs in patient samples is expected to provide a noninvasive, relatively quick and inexpensive blood test that can be both diagnostic and prognostic, which may be a valuable adjunct to routine biopsy.

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 3625. doi:1538-7445.AM2012-3625

Nucleotide sequence variation within the human tyrosine kinase B neurotrophin receptor gene: association with antisocial alcohol dependence

To identify sequence variants in genes that may have roles in neuronal responses to alcohol, we resequenced the 5' region of tyrosine kinase B neurotrophin receptor gene (NTRK2) and determined linkage disequilibrium (LD) values, haplotype structure, and performed association analyses using 43 single nucleotide polymorphisms (SNPs) covering the entire NTRK2 region in a Finnish Caucasian sample of 229 alcohol-dependent subjects with antisocial personality disorder (ASPD) and 287 healthy controls. Individually, three SNPs were associated with alcohol dependence and alcohol abuse (AD) (P-value from 0.0019 to 0.0059, significance level was set at P<or=0.01 corrected for multiple testing), whereas a common 18 locus haplotype within the largest LD block of NTRK2, a 119-kb region containing the 5' flanking region and exons 1-15, was marginally overrepresented in control subjects compared to AD individuals (global P=0.057). Taken together, these results support a role for the NTRK2 gene in addiction in a Caucasian population with AD and a subtype of ASPD.