Genomic Complexity Predicts Resistance to Endocrine Therapy and CDK4/6 Inhibition in Hormone Receptor-Positive (HR+)/HER2-Negative Metastatic Breast Cancer

PURPOSE

Clinical biomarkers to identify patients unlikely to benefit from CDK4/6 inhibition (CDK4/6i) in combination with endocrine therapy (ET) are lacking. We implemented a comprehensive circulating tumor DNA (ctDNA) analysis to identify genomic features for predicting and monitoring treatment resistance.

EXPERIMENTAL DESIGN

ctDNA was isolated from 216 plasma samples collected from 51 patients with hormone receptor-positive (HR+)/HER2-negative (HER2-) metastatic breast cancer (MBC) on a phase II trial of palbociclib combined with letrozole or fulvestrant (NCT03007979). Boosted whole-exome sequencing (WES) was performed at baseline and clinical progression to evaluate genomic alterations, mutational signatures, and blood tumor mutational burden (bTMB). Low-pass whole-genome sequencing was performed at baseline and serial timepoints to assess blood copy-number burden (bCNB).

RESULTS

High bTMB and bCNB were associated with lack of clinical benefit and significantly shorter progression-free survival (PFS) compared with patients with low bTMB or low bCNB (all P < 0.05). Dominant APOBEC signatures were detected at baseline exclusively in cases with high bTMB (5/13, 38.5%) versus low bTMB (0/37, 0%; P = 0.0006). Alterations in ESR1 were enriched in samples with high bTMB (P = 0.0005). There was a high correlation between bTMB determined by WES and bTMB determined using a 600-gene panel (R = 0.98). During serial monitoring, an increase in bCNB score preceded radiographic progression in 12 of 18 (66.7%) patients.

CONCLUSIONS

Genomic complexity detected by noninvasive profiling of bTMB and bCNB predicted poor outcomes in patients treated with ET and CDK4/6i and identified early disease progression before imaging. Novel treatment strategies including immunotherapy-based combinations should be investigated in this population.

Abstract 6130: Comprehensive genomic and transcriptomic profiling of acral lentiginous melanoma

Background: Acral lentiginous melanoma (ALM) is a rare melanoma subtype found on the palms, soles and nailbeds. Outcomes are poor for patients with advanced ALM, and novel treatment approaches are needed. Here, we seek to explore the global genomic and transcriptomic landscape of ALM.

Methods: A total of 699 primary CM (non-ALM cutaneous melanoma) and 18 primary ALM samples underwent next generation sequencing of DNA (592 Gene Panel, NextSeq, or WES, NovaSeq), and whole transcriptome sequencing (NovaSeq, WTS). Wilcoxon, Fisher’s exact test were used to determine statistical significance (displayed as p value without and q value with multi comparison correction). xCell, HLA subtyping, neoantigen load (HBA: high binding affinity; IBA: intermediate binding affinity; LBA: low binding affinity), Interferon gamma score (IFNγ), MAPK pathway activity score (MPAS), and Innate anti-PD-1 Resistance score (IPRES) were calculated by mRNA expression. Global differentially regulated genes were assessed via limma R package (C: log fold change).

Results: The most common alterations in ALM included NRAS (22.2%), NF1 (20.0%), BRAF (11.1%) and CDKN2A (11.1%) mutations, and EMSY (22.2%), ELL (11.1%), MAML2 (11.1%), MRE11(11.1%) and PIK3R2 (11.1%) amplifications. ALM had lower TMB (1.5 v 9 Mut/Mb, q&lt;.0001), lower rates of TERT (0 v 66.7%, q&lt;.01) and a trend towards lower BRAF (11.1 v 39.8%, p&lt;.05) mutations, compared to CM. Neoantigen load was lower in ALM compared to CM, regardless of MHC binding affinity (HBA: 1 vs 4, q &lt;.01; IBA: 2 vs 7, q &lt;.001; LBA: 7 vs 18, q &lt;.001). HLA-G RNA expression was upregulated in ALM with respect to CM (C = 1.14, q &lt;.001). ALM showed less CD4+ T cell Th1 (C = -0.8, p &lt;.05), B cell plasma (C = -1.8, p&lt;.05), and γδ T cells (C = -5.9, p&lt;.05), but more CD4+ T cell central memory cell (C = 9.7, p&lt;.05), stroma score (C = 1.7, p&lt;.05), and endothelial cells (C = 1.7, p&lt;.05), versus CM. There was a trend towards lower IFNγ in ALM (-0.4 vs -0.3, p = .1), but no difference in IPRES, compared to CM (-0.09 vs 0.1, p=.9). MPAS scores were lower for ALM compared to CM (-1.6 vs -0.4, q&lt;.001), even when stratifying by BRAF (q&lt;.05) or NF1 (q&lt;.05) status, but not NRAS (p = .22). Pathways related to keratinization (p &lt;.0001) and amyloid fiber formation (p&lt;.0001) were enriched in ALM, due to overexpression of KRT16 (C = 3.5, q &lt;.01), KRT6B (C = 3.4, q &lt;.01), and KRT17 (C = 3.2, q &lt;.05), among others.

Conclusion: ALM has distinct immunologic features, including upregulation of HLA-G, as well as lower MAPK activation in ALM, compared to CM, highlighting the need for novel therapeutic approaches in the treatment of this rare subtype.

Citation Format: Gino K. In, Jun Yin, Phillip Walker, Justin Moser, Joanne Xiu, Kelsey Poorman, Geoffery T. Gibney, Matthew Oberley, Thuy Phung, Leonel F. Hernandez-Aya, Jose Lutzky, Wolfgang Michael Korn, Michael B. Atkins. Comprehensive genomic and transcriptomic profiling of acral lentiginous melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6130.

Abstract 5625: Molecular and immunologic characterization of HRAS mutations in a cohort of 6,329 patients with cutaneous melanoma

Background: Activation in RAS pathway has been associated with cancer development. Three RAS family members, including NRAS, KRAS and HRAS are frequently mutated across various cancer types, where NRAS mutations are present in 15-20% of melanomas. NRAS-mutant melanomas (NRASm) have been extensively characterized. However, molecular and clinical implications of HRAS mutations (HRASm) in melanoma are less well understood.

Methods: A total of 6329 melanoma samples were subjected to comprehensive molecular profiling at Caris Life Sciences. Analyses included next generation sequencing of DNA (592 Gene Panel, NextSeq; whole exome sequencing, NovaSEQ), RNA (NovaSeq, whole transcriptome sequencing, WTS) and IHC. MPAS scores to evaluate MAPK pathway activation, IFN scores, QuantiSeq, neoantigen load (high, intermediate, low binding affinity: HBA, IBA and LBA) and GSEA were calculated from mRNA expression data. Wilcoxon, Fisher’s exact were used to determined statistical significance (p value without and q value with multi comparison correction; FDR for GSEA). The reference cohort was the entire melanoma cohort (MC).

Results: HRASm were identified in 69 (1.09%) of melanoma samples (hotspots mutations: G13, 40%; Q61, 34%; G12, 18% and others, 9%). HRASm and NRASm had different genomic landscapes: HRASm were significantly associated with a higher mutation rate of NF1 (43.2% vs 27.7%, p&lt;.05), ARID1A (17.2% vs 6.3%, p&lt;.05), B2M (14.3% vs 2.4%, p&lt;.05), RAF1 (12.2% vs 1.4, p&lt;.0001), CTNNB1 (9.1% vs 3.3%, p&lt;.05) and higher amplifications of EMSY (11.8% vs 1.8%, p&lt;.01), MRE11 (4.3% vs 0.5%, p&lt;.05), whereas NRASm harbored less NF1 (14.8% vs 27.7%, q&lt;.0001 ), BRAF (6.9% vs 39.9%, p &lt;.0001), PTEN (3.9% vs 6.9%, q &lt;.05), KIT (0.8% vs 4.4%, q &lt;.0001) mutations and less amplification PDGFR (0.4% vs 1.3%, p&lt;.05), BRAF (0.2% vs 1.4%, p&lt;.05), KIT (0.2% vs 2.1%, q&lt;.05) when comparing to MC. Both HRASm and NRASm had higher MPAS scores than MC (HRASm, 0.24; NRASm, 0.11; MC, -0.41, q&lt;.001). In addition, HRASm showed higher TMB (HRASm, 68.1%; NRASm, 56.9%; MC, 50.0%, q&lt;.05), relatively higher IFN scores (HRASm, 0.16; NRASm, -0.23; MC, -0.24, q = .16) and higher neoantigen load (HBA: HRASm, 10.5; NRASm, 4; MC, 4, p &lt; .05; IBA: HRASm, 17.5; NRASm, 8 MC, 7, p &lt; .05; LBA: HRASm, 37.5; NRASm, 21; MC, 19, p =.1) when compared to NRASm and MC. Lastly, suppression of angiogenesis pathway was observed in both HRASm (NES = 1.7, FDR&lt;.05) and NRASm with respect to MC (NES = 1.4, FDR&lt;.25).

Conclusions: The genomic landscape of HRASm are significantly different from that of NRASm, implying their distinct roles in tumorigenesis. HRASm also demonstrated higher MAPK activation, suggesting that they could potentially benefit from agents targeting on this pathway. In addition, HRASm displayed more immunogenic features, associated with down-regulation of angiogenesis pathway, revealing a potential higher susceptibility of HRASm to immunotherapy.

Citation Format: Leonel F. Hernandez-Aya, Estelamari Rodriguez, Aparna Nallagangula, Jun Yin, Phillip Walker, Joanne Xiu, Justin Moser, Gino K. In, David Spetzler, Geoffery T. Gibney, Matthew Oberley, Thuy Phung, Michael Atkins, Dave S. Hoon, Wolfgang Michael Korn, Jose Lutzky, Gilberto Lopes. Molecular and immunologic characterization of HRAS mutations in a cohort of 6,329 patients with cutaneous melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5625.

Phase I Study of Safety, Tolerability, and Efficacy of Tebentafusp Using a Step-Up Dosing Regimen and Expansion in Patients With Metastatic Uveal Melanoma

PURPOSE

This phase I study aimed to define the recommended phase II dose (RP2D) of tebentafusp, a first-in-class T-cell receptor/anti-CD3 bispecific protein, using a three-week step-up dosing regimen, and to assess its safety, pharmacokinetics, pharmacodynamics, and preliminary clinical activity in patients with metastatic uveal melanoma (mUM).

METHODS

In this open-label, international, phase I/II study, HLA-A*02 or HLA-A*02:01+ patients with mUM received tebentafusp 20 μg once in week 1 and 30 μg once in week 2. Dose escalation (starting at 54 μg) began at week 3 in a standard 3 + 3 design to define RP2D. Expansion-phase patients were treated at the RP2D (20-30-68 μg). Blood and tumor samples were collected for pharmacokinetics/pharmacodynamics assessment, and treatment efficacy was evaluated for all patients with baseline efficacy data as of December 2017.

RESULTS

Between March 2016 and December 2017, 42 eligible patients who failed a median of two previous treatments were enrolled: 19 in the dose escalation cohort and 23 in an initial dose expansion cohort. Of the dose levels investigated, 68 μg was identified as the RP2D. Most frequent treatment-emergent adverse events regardless of attribution were pyrexia (91%), rash (83%), pruritus (83%), nausea (74%), fatigue (71%), and chills (69%). Toxicity attenuated following the first three doses. The overall response rate was 11.9% (95% CI, 4.0 to 25.6). With a median follow-up of 32.4 months, median overall survival was 25.5 months (range, 0.89-31.1 months) and 1-year overall survival rate was 67%. Treatment was associated with increased tumor T-cell infiltration and transient increases in serum inflammatory mediators.

CONCLUSION

Using a step-up dosing regimen of tebentafusp allowed a 36% increase in the RP2D compared with weekly fixed dosing, with a manageable side-effect profile and a signal of efficacy in mUM.

BAMM (BRAF Autophagy and MEK Inhibition in Melanoma): A Phase I/II Trial of Dabrafenib, Trametinib, and Hydroxychloroquine in Advanced BRAFV600-mutant Melanoma

PURPOSE

Autophagy is a resistance mechanism to BRAF/MEK inhibition in BRAFV600-mutant melanoma. Here we used hydroxychloroquine (HCQ) to inhibit autophagy in combination with dabrafenib 150 mg twice daily and trametinib 2 mg every day (D+T).

PATIENTS AND METHODS

We conducted a phase I/II clinical trial in four centers of HCQ + D+T in patients with advanced BRAFV600-mutant melanoma. The primary objectives were the recommended phase II dose (RP2D) and the one-year progression-free survival (PFS) rate of >53%.

RESULTS

Thirty-four patients were evaluable for one-year PFS rate. Patient demographics were as follows: elevated lactate dehydrogenase: 47%; stage IV M1c/M1d: 52%; prior immunotherapy: 50%. In phase I, there was no dose-limiting toxicity. HCQ 600 mg orally twice daily with D+T was the RP2D. The one-year PFS rate was 48.2% [95% confidence interval (CI), 31.0%-65.5%], median PFS was 11.2 months (95% CI, 5.4-16.9 months), and response rate (RR) was 85% (95% CI, 64%-95%). The complete RR was 41% and median overall survival (OS) was 26.5 months. In a patient with elevated LDH (n = 16), the RR was 88% and median PFS and OS were 7.3 and 22 months, respectively.

CONCLUSIONS

HCQ + D+T was well tolerated and produced a high RR but did not meet criteria for success for the one-year PFS rate. There was a high proportion of patients with pretreated and elevated LDH, an increasingly common demographic in patients receiving targeted therapy. In this difficult-to-treat population, the RR and PFS were encouraging. A randomized trial of D+T + HCQ or placebo in patients with BRAFV600-mutant melanoma with elevated LDH and previous immunotherapy is being conducted.

Breast cancer-derived GM-CSF regulates arginase 1 in myeloid cells to promote an immunosuppressive microenvironment

Tumor-infiltrating myeloid cells contribute to the development of the immunosuppressive tumor microenvironment. Myeloid cell expression of arginase 1 (ARG1) promotes a protumor phenotype by inhibiting T cell function and depleting extracellular l-arginine, but the mechanism underlying this expression, especially in breast cancer, is poorly understood. In breast cancer clinical samples and in our mouse models, we identified tumor-derived GM-CSF as the primary regulator of myeloid cell ARG1 expression and local immune suppression through a gene-KO screen of breast tumor cell-produced factors. The induction of myeloid cell ARG1 required GM-CSF and a low pH environment. GM-CSF signaling through STAT3 and p38 MAPK and acid signaling through cAMP were required to activate myeloid cell ARG1 expression in a STAT6-independent manner. Importantly, breast tumor cell-derived GM-CSF promoted tumor progression by inhibiting host antitumor immunity, driving a significant accumulation of ARG1-expressing myeloid cells compared with lung and melanoma tumors with minimal GM-CSF expression. Blockade of tumoral GM-CSF enhanced the efficacy of tumor-specific adoptive T cell therapy and immune checkpoint blockade. Taken together, we show that breast tumor cell-derived GM-CSF contributes to the development of the immunosuppressive breast cancer microenvironment by regulating myeloid cell ARG1 expression and can be targeted to enhance breast cancer immunotherapy.

Early Assessment Window for Predicting Breast Cancer Neoadjuvant Therapy using Biomarkers, Ultrasound, and Diffuse Optical Tomography

PURPOSE

The purpose of the study was to assess the utility of tumor biomarkers, ultrasound (US) and US-guided diffuse optical tomography (DOT) in early prediction of breast cancer response to neoadjuvant therapy (NAT).

METHODS

This prospective HIPAA compliant study was approved by the institutional review board. Forty one patients were imaged with US and US-guided DOT prior to NAT, at completion of the first three treatment cycles, and prior to definitive surgery from February 2017 to January 2020. Miller-Payne grading was used to assess pathologic response. Receiver operating characteristic curves (ROCs) were derived from logistic regression using independent variables, including: tumor biomarkers, US maximum diameter, percentage reduction of the diameter (%US), pretreatment maximum total hemoglobin concentration (HbT) and percentage reduction in HbT (%HbT) at different treatment time points. Resulting ROCs were compared using area under the curve (AUC). Statistical significance was tested using two-sided two-sample student t-test with P < 0.05 considered statistically significant. Logistic regression was used for ROC analysis.

RESULTS

Thirty-eight patients (mean age = 47, range 24-71 years) successfully completed the study, including 15 HER2 + of which 11 were ER + ; 12 ER + or PR + /HER2-, and 11 triple negative. The combination of HER2 and ER biomarkers, %HbT at the end of cycle 1 (EOC1) and %US (EOC1) provided the best early prediction, AUC = 0.941 (95% CI 0.869-1.0). Similarly an AUC of 0.910 (95% CI 0.810-1.0) with %US (EOC1) and %HbT (EOC1) can be achieved independent of HER2 and ER status. The most accurate prediction, AUC = 0.974 (95% CI 0.933-1.0), was achieved with %US at EOC1 and %HbT (EOC3) independent of biomarker status.

CONCLUSION

The combined use of tumor HER2 and ER status, US, and US-guided DOT may provide accurate prediction of NAT response as early as the completion of the first treatment cycle.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02891681. https://clinicaltrials.gov/ct2/show/NCT02891681 , Registration time: September 7, 2016.

Treatment response as predictor for brain metastasis in triple negative breast cancer: A score-based model

BACKGROUND

Triple negative breast cancer (TNBC) has worse prognosis than other subtypes of breast cancer, and many patients develop brain metastasis (BM). We developed a simple predictive model to stratify the risk of BM in TNBC patients receiving neo-adjuvant chemotherapy (NAC), surgery, and radiation therapy (RT).

METHODS

Patients with TNBC who received NAC, surgery, and RT were included. Cox proportional hazards method was used to evaluate factors associated with BM. Significant factors predictive for BM on multivariate analysis (MVA) were used to develop a risk score. Patients were divided into three risk groups: low, intermediate, and high. A receiver operating characteristic (ROC) curve was drawn to evaluate the value of the risk group in predicting BM. This predictive model was externally validated.

RESULTS

A total of 160 patients were included. The median follow-up was 47.4 months. The median age at diagnosis was 49.9 years. The 2-year freedom from BM was 90.5%. Persistent lymph node positivity, HR 8.75 (1.76-43.52, P = 0.01), and lack of downstaging, HR 3.46 (1.03-11.62, P = 0.04), were significant predictors for BM. The 2-year rate of BM was 0%, 10.7%, and 30.3% (P < 0.001) in patients belonging to low-, intermediate-, and high-risk groups, respectively. Area under the ROC curve was 0.81 (P < 0.001). This model was externally validated (C-index = 0.79).

CONCLUSIONS

Lack of downstaging and persistent lymph node positivity after NAC are associated with development of BM in TNBC. This model can be used by the clinicians to stratify patients into the three risk groups to identify those at increased risk of developing BM and potentially impact surveillance strategies.

Abstract P1-15-05: Is absolute lymphocyte count associated with platinum-sensitivity? A phase II single arm study evaluating the efficacy of neoadjuvant carboplatin and docetaxel in triple negative breast cancer

Background: Platinum-based chemotherapy is still considered investigational for the treatment of sporadic triple negative breast cancer (TNBC). Since patients with TNBC have a high rate of chemotherapy resistance, it is critical to identify platinum-sensitive individuals prior to initiating therapy. Higher absolute lymphocyte count (ALC) is associated with improved clinical response to anthracycline-based chemotherapy, the current standard of care in TNBC. We report the initial results of a phase II single arm study evaluating the efficacy of neoadjuvant carboplatin and docetaxel in TNBC. We also report results of an exploratory analysis assessing whether ALC can be used to predict pathologic complete response (pCR) after treatment with platinum-based chemotherapy.

Patients and Methods: 78 patients with clinical stage II or III TNBC have been enrolled in this ongoing study evaluating the efficacy of neoadjuvant carboplatin and docetaxel (NCT201404107). Patients received docetaxel 75 mg/m2 and carboplatin AUC 6 every three weeks for a total of 6 cycles. Blood samples were collected prior to each cycle, and a posttreatment sample was collected &gt; 3 weeks after completing cycle 6. pCR was defined as no residual invasive disease in the breast, with or without ductal carcinoma in situ, and no tumor deposits in sampled lymph nodes. Baseline characteristics of patients were summarized with descriptive statistics. Univariate and multivariate logistic regression analyses were used to identify factors associated with pCR.

Results: Out of the 78 enrolled patients, 60 have completed all 6 treatment cycles and surgery. The preliminary pCR rate is 46.7%. Age, race, clinical stage, and tumor grade determined at time of diagnosis were not significantly different between pCR patients and non-pCR patients. In univariate analyses, patients with higher ALCs at the posttreatment time point were more likely to have pCR than those who had lower ALCs (OR 5.5, 95% CI 1.5-20.7, p=0.011). Additionally, patients who had higher minimum ALCs were also more likely to have pCR (OR 9.1, 95% CI 1.5-54.9, p=0.016). Baseline ALC values were not associated with pCR. The associations of posttreatment and minimum ALCs to pCR remained statistically significant even after controlling for age and clinical stage at time of diagnosis (posttreatment ALC OR 7.6, 95% CI 1.7-34.8, p=0.009; minimum ALC OR 9.0, 95% CI 1.5-55.2, p=0.018).

Conclusion: The pCR rate of our cohort is similar to that of other trials evaluating neoadjuvant platinum-based chemotherapy in TNBC. Baseline ALC did not predict which patients would achieve pCR. However, the associations of posttreatment and minimum ALCs with pCR indicate patients who are able to maintain a robust population of circulating lymphocytes throughout treatment with platinum-based chemotherapy are more likely to respond favorably. The link between patient immunity and platinum-based chemotherapy suggests addition of immunotherapy agents to neoadjuvant chemotherapy may improve patient outcomes.

Citation Format: Chen I, Guo F, Summa T, Luo J, Ellis MJ, Ma CX, Weilbaecher KN, Naughton MJ, Suresh R, Peterson LL, Cherian MA, Bose R, Frith AE, Hernandez-Aya LF, Gillanders WE, Ademuyiwa FO. Is absolute lymphocyte count associated with platinum-sensitivity? A phase II single arm study evaluating the efficacy of neoadjuvant carboplatin and docetaxel in triple negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-15-05.

Quantitative Spatial Profiling of PD-1/PD-L1 Interaction and HLA-DR/IDO-1 Predicts Improved Outcomes of Anti-PD-1 Therapies in Metastatic Melanoma

Purpose: PD-1/L1 axis-directed therapies produce clinical responses in a subset of patients; therefore, biomarkers of response are needed. We hypothesized that quantifying key immunosuppression mechanisms within the tumor microenvironment by multiparameter algorithms would identify strong predictors of anti-PD-1 response.Experimental Design: Pretreatment tumor biopsies from 166 patients treated with anti-PD-1 across 10 academic cancer centers were fluorescently stained with multiple markers in discovery (n = 24) and validation (n = 142) cohorts. Biomarker-positive cells and their colocalization were spatially profiled in pathologist-selected tumor regions using novel Automated Quantitative Analysis algorithms. Selected biomarker signatures, PD-1/PD-L1 interaction score, and IDO-1/HLA-DR coexpression were evaluated for anti-PD-1 treatment outcomes.Results: In the discovery cohort, PD-1/PD-L1 interaction score and/or IDO-1/HLA-DR coexpression was strongly associated with anti-PD-1 response (P = 0.0005). In contrast, individual biomarkers (PD-1, PD-L1, IDO-1, HLA-DR) were not associated with response or survival. This finding was replicated in an independent validation cohort: patients with high PD-1/PD-L1 and/or IDO-1/HLA-DR were more likely to respond (P = 0.0096). These patients also experienced significantly improved progression-free survival (HR = 0.36; P = 0.0004) and overall survival (HR = 0.39; P = 0.0011). In the combined cohort, 80% of patients exhibiting higher levels of PD-1/PD-L1 interaction scores and IDO-1/HLA-DR responded to PD-1 blockers (P = 0.000004). In contrast, PD-L1 expression was not predictive of survival.Conclusions: Quantitative spatial profiling of key tumor-immune suppression pathways by novel digital pathology algorithms could help more reliably select melanoma patients for PD-1 monotherapy. Clin Cancer Res; 24(21); 5250-60. ©2018 AACR.

Stereotactic radiosurgery and immunotherapy in melanoma brain metastases: Patterns of care and treatment outcomes

PURPOSE

Preclinical studies have suggested that radiation therapy (RT) enhances antitumor immune response and can act synergistically when administered with immunotherapy. However, this effect in melanoma brain metastasis is not well studied. We aim to explore the clinical effect of combining RT and immunotherapy in patients with melanoma brain metastasis (MBM).

MATERIALS AND METHODS

Patients with MBM between 2011 and 2013 were obtained from the National Cancer Database. Patients who did not have identifiable sites of metastasis and who did not receive RT for the treatment of their MBM were excluded. Patients were separated into cohorts that received immunotherapy versus patients who did not. Univariable and multivariable analyses were performed using Cox model to determine predictors of OS. Kaplan-Meier method was used to compare OS. Univariable and multivariable analyses using logistic regression model were used to determine the factors predictive for the use of immunotherapy. Propensity score analysis was used to account for differences in baseline patient characteristics between the RT and RT + immunotherapy groups. Significance was defined as a P value ≤ 0.05.

RESULTS

A total of 1104 patients were identified: 912 received RT alone and 192 received RT plus immunotherapy. The median follow-up time was 6.4 (0.1-56.8) months. Patients with extracranial disease (OR 1.603, 95% CI 1.146-2.243, P = 0.006), and patients receiving SRS (OR 1.955, 95% CI 1.410-2.711, P < 0.001) as compared to WBRT, had a higher likelihood of being treated with immunotherapy. The utilization of immunotherapy had nearly doubled between 2011 and 2013 (12.9-22.8%). On multivariable analysis, factors associated with superior OS were younger age, lower medical comorbidities, lack of extracranial disease, and treatment with immunotherapy and SRS. The median OS was 11.1 (8.9-13.4) months in RT plus immunotherapy vs. 6.2 (5.6-6.8) months in RT alone (P < 0.001), which remained significant after propensity score matching.

CONCLUSIONS

An increase in trend for the use of immunotherapy was noted, however, an overwhelming majority of the patients with this disease are still treated without immunotherapy. Addition of immunotherapy to RT is associated with improved OS in MBM. Given the selection biases that are inherent in this analysis, prospective trials investigating the combination of RT, especially SRS and immunotherapy are warranted.

Chemotherapy principles of managing stage IV breast cancer in the United States

The therapeutic landscape for metastatic breast cancer (MBC) has expanded greatly over the last three decades with an increasing availability of targeted therapies for specific breast cancer subtypes. However, cytotoxic chemotherapy remains an essential component for the management of endocrine refractory or triple negative MBC. Multiple chemotherapy agents have demonstrated activity in MBC as single agents and in combination. While taxanes are frequently recommended as the initial treatment of metastatic disease, capecitabine is a convenient oral therapy with well received toxicity profile. Eribulin is the only agent that demonstrated overall survival (OS) benefit in a phase III clinical trial when compared to treatment of physician choice in heavily pre-treated patients. Ixabepilone, gemcitabine, vinorelbine and platinum agents have demonstrated activity and, therefore, constitute additional therapeutic options. In this review, we will discuss the data supporting the use of different cytotoxic agents and the general principles in guiding the use of chemotherapy.

Abstract 4454: Targeting the gp130 receptor in preclinical models of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer (BC) with poor clinical outcomes and limited therapeutic options. To date, efforts to implement targetted therapy in TNBC have had limited success. Cumulative evidence suggest that cancer stem cells (CSCs) drive resistance to therapy, tumor recurrence, and may play a determinant role in the aggressive biology of TNBC. Recent studies indicate that CSCs are in reciprocal interaction with tumor microenvironment through cytokine-mediated signaling pathways. IL-6 is emerging as an important mediator of tumor growth and CSC survival. IL-6 is the most studied ligand of the gp130 receptor, which is a potent activator of the JAK/STAT3 signaling pathway important in survival and proliferation. The gp130 receptor is emerging as a promising target for cancer therapy. SC144 is a novel first-in-class gp130 inhibitor that has shown preclinical efficacy in ovarian cancer models. This study explores the effect of gp130 inhibition with SC144 on TNBC preclinical models.

Methods: SC144 was provided by Dr. Neamati's laboratory currently at the University of Michigan. We conducted in vitro studies using well-characterized human BC cell lines with a triple-negative phenotype. The effect of the novel compound SC144 on TNBC cell lines was evaluated using MTT assays for growth inhibition, ALDEFLUOR assay for identification of CSCs, ELISA tests for cytokine levels, and qRT-PCR for gene expression analysis.

Results: SC144 inhibits cell growth in the TNBC cell lines SUM159, SUM149, MDAMB231, and HCC38 with IC50 values in a submicromolar range (0.87+0.17 μmol/L, 0.9+0.1 μmol/L, 0.5 μmol/L, 0.4 μmol/L, respectively). In an in vitro culture system of the TNBC cell line SUM159, docetaxel treatment induces a three-fold increase in IL-6 levels by ELISA and increases the CSC population measured by ALDEFLUOR. Pretreatment of SUM159 cells with SC144 significantly sensitized cells to docetaxel. Treatment of SUM159 cells with SC144 in addition to docetaxel significantly reduced the ALDH+ population measured by ALDEFLUOR compared to docetaxel alone (7.79+1% vs 22.23+5%). Investigating the potential effect of SC144 on the CSC population, we found a higher expression level of the IL-6 receptor in ALDH+ cells compared to ALDH- and the bulk population. Furthermore, in SUM159 cells treated with SC144 vs. control for 24 hours we found a significant decrease on expression of genes with documented relevance in CSC maintenance including CD44 (0.08 vs. 0.13), ALDH1a1 (0.001 vs. 0.006), STAT1 (0.004 vs. 0.024) and STAT3 (0.003 vs. 0.014). The in vivo study to test the efficacy of SC144 in a SUM159 xenograft model is undergoing.

Conclusions: SC144, a novel gp130 inhibitor, has antitumor activity in human BC cell lines with the triple-negative phenotype. SC144 sensitizes cells to docetaxel therapy, and demonstrates an inhibitory effect on the CSC subpopulation. These findings identify a potential therapeutic target for TNBC.

Citation Format: Leonel F. Hernandez-Aya, Yajing Liu, Kelsey Kerr, Shuzo Tamura, Nouri Neamati, Max S. Wicha, Monika L. Burness. Targeting the gp130 receptor in preclinical models of triple-negative breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4454. doi:10.1158/1538-7445.AM2015-4454

Why Chemotherapy Should be Given Early for Men with Metastatic Prostate Cancer

Metastatic hormone-sensitive prostate cancer (mHSPC) is an incurable disease, and despite a high response rate to androgen-deprivation therapy (ADT), outcomes have not significantly changed for many decades. Earlier attempts at multitargeted strategies with the addition of cytotoxic chemotherapy to ADT did not affect survival. As more effective therapies are emerging, including cytotoxic therapy for patients with metastatic castrate-resistant prostate cancer (mCRPC), there is increasing interest for testing these drugs earlier in the disease course. The premise is that agents with clinical benefit in advanced mCRPC may have a better effect if used preemptively before the development of significant resistance and to attack earlier de novo androgen resistant/independent clones. The recent results of the phase III clinical trial E3805 investigating ADT with or without docetaxel in mHSPC provide compelling support for this strategy. Docetaxel combined with ADT significantly improved overall survival from 44 to 57.6 months (p=0.0003), particularly in patients with high-volume disease (from 32.2 to 49.2 months; p=0.0006). Longer follow-up is needed to assess the effect on patients with low disease burden. Further studies are needed to further maximize the antitumor effect in patients with mHSPC and to investigate the effects of advancing therapy to this disease setting on the efficacy of respective agents in the castration-resistant setting.

Adjuvant systemic therapies in breast cancer

Although some women with early breast cancer (BC) may be cured with loco-regional treatment alone, up to 20% of patients with early-stage BC will ultimately experience treatment failure and recurrence. A substantial portion of the success in improving clinical outcomes of patients with BC is related to the standardized use of adjuvant therapies. The identification of tumor subtypes with prognostic value has contributed to the idea of tailoring treatments using biologic predictive factors to identify the patients who will most likely respond to therapy and minimize the exposure of "nonresponders" to the side effects of the treatment.

Triple-negative breast cancer is not a contraindication for breast conservation

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive subtype shown to have a high risk of locoregional recurrence (LRR). The purpose of this study was to determine the impact of operation type on LRR in TNBC patients.

METHODS

A total of 1325 patients with TNBC who underwent breast-conserving therapy (BCT) or mastectomy from 1980 to the present were identified. Clinical and pathological factors were compared by the chi-square test. LRR-free survival (LRRFS), distant metastasis-free survival, and overall survival were estimated by the Kaplan-Meier method. Multivariate analysis was performed by the Cox proportional hazard models.

RESULTS

BCT was performed in 651 patients (49%) and mastectomy in 674 (51%). The mastectomy group had larger tumors, a higher incidence of lymphovascular invasion, and higher pathologic N stage (all P < 0.001). At 62-month median follow-up, LRR was seen in 170 (26%) in the BCT group and 203 (30%) in the mastectomy group. Five-year LRRFS rates were higher in the BCT group (76% vs. 71%, P = 0.032), as was distant metastasis-free survival (68% vs. 54%, P < 0.0001) and overall survival (74% vs. 63%, P < 0.0001). On multivariate analysis, T stage (hazard ratio [HR] 1.37, P = 0.006), high nuclear grade (HR 1.92, P = 0.002), lymphovascular invasion (HR 1.93, P < 0.0001), close/positive margins (HR 1.89, P < 0.0001), and use of non-anthracycline or taxane-based adjuvant chemotherapy (HR 2.01, P < 0.0001) increased the LRR risk, while age >50 years was protective (HR 0.73, P = 0.007). Operation type (mastectomy vs. BCT, HR 1.07, P = 0.55) was not statistically significant.

CONCLUSIONS

BCT is not associated with increased LRR rates compared to mastectomy. TNBC should not be considered a contraindication for breast conservation.

Impact of low estrogen/progesterone receptor expression on survival outcomes in breast cancers previously classified as triple negative breast cancers

PURPOSE

To evaluate the impact of low estrogen/progesterone receptor (ER/PR) expression and effect of endocrine therapy on survival outcomes in human epidermal growth factor receptor 2 (HER2)-negative tumors with ER/PR <10%, previously labeled as triple negative.

METHODS

In a retrospective review, 1257 patients were categorized according their ER/PR percentages into 3 groups, ER/PR <1% (group A), ER/PR 1% to 5% (group B), and ER/PR 6% to 10% (group C). Kaplan-Meier product limit method was used to estimate survival outcomes. Cox proportional hazards models was used to adjust for patient and tumor characteristics.

RESULTS

Groups A, B, and C had 897 (71.4%), 241 (19.2%), and 119 (9.4%) patients, respectively. After a median follow-up of 40 months there was no significant difference in 3-year recurrence-free survival (RFS): 64%, 67%, and 77% (P = .34) or overall survival (OS): 79%, 81%, and 88% (P = .33) for groups A, B, and C, respectively. ER/PR expression was not an independent predictor for RFS (hazard ratio [HR], 1.10; 95% confidence interval [CI], 0.86-1.39; P = .46 for group B, and HR, 0.96; 95% CI, 0.66-1.38; P = .81 for group C, compared with group A), or OS (HR, 1.11; 95% CI, 0.84-1.46; P = .46 for group B, and HR, 0.94; 95% CI, 0.63-1.42; P = .78 for group C, compared with group A). Endocrine therapy had no impact on survival outcomes (RFS: P = .10; OS: P = .45) among groups.

CONCLUSIONS

In this cohort, a low ER/PR level (1%-5%) does not appear to have any significant impact on survival outcomes. There was a tendency for survival advantages in the ER/PR 6% to 10% is seen. Benefit of endocrine therapy in these patients is unclear.

Nodal status and clinical outcomes in a large cohort of patients with triple-negative breast cancer

PURPOSE

To evaluate the clinical outcomes and relationship between tumor size, lymph node status, and prognosis in a large cohort of patients with confirmed triple receptor-negative breast cancer (TNBC).

PATIENTS AND METHODS

We reviewed 1,711 patients with TNBC diagnosed between 1980 and 2009. Patients were categorized by tumor size and nodal status. Kaplan-Meier product limit method was used to calculate overall survival (OS) and relapse-free survival (RFS). A Sidak adjustment was used for multiple group comparisons. Cox proportional hazards models were fit to determine the association of tumor size and nodal status with survival outcomes after adjustment for other patient and disease characteristics.

RESULTS

Median age was 48 years (range, 21 to 87 years). At a median follow-up of 53 months (range, 0.7 to 317 months), there were 614 deaths and 747 recurrences. The 5-year OS was 80% for node-negative patients (N0), 65% for one to three positive lymph nodes (N1), 48% for four to nine positive lymph nodes (N2), and 44% for ≥ 10 positive lymph nodes (N3; P < .0001). The 5-year RFS rates were 67% for N0, 52% for N1, 36% for N2, and 33% for N3 (P < .0001). Pairwise comparison by nodal status showed that when comparing N0 with node-positive disease, there was a significant difference in OS and RFS (P < .001 all comparisons). However, when comparing N1 with N2 and N3 disease regardless of tumor size, there were no significant differences in OS or RFS.

CONCLUSION

In patients with TNBC, once there is evidence of lymph node metastasis, the prognosis may not be affected by the number of positive lymph nodes.

Targeting the phosphatidylinositol 3-kinase signaling pathway in breast cancer

The phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) network plays a key regulatory function in cell survival, proliferation, migration, metabolism, angiogenesis, and apoptosis. Genetic aberrations found at different levels, either with activation of oncogenes or inactivation of tumor suppressors, make this pathway one of the most commonly disrupted in human breast cancer. The PI3K-dependent phosphorylation and activation of the serine/threonine kinase AKT is a key activator of cell survival mechanisms. The activation of the oncogene PIK3CA and the loss of regulators of AKT including the tumor suppressor gene PTEN are mutations commonly found in breast tumors. AKT relieves the negative regulation of mTOR to activate protein synthesis and cell proliferation through S6K and 4EBP1. The common activation of the PI3K pathway in breast cancer has led to the development of compounds targeting the effector mechanisms of the pathway including selective and pan-PI3K/pan-AKT inhibitors, rapamycin analogs for mTOR inhibition, and TOR-catalytic subunit inhibitors. The influences of other oncogenic pathways such as Ras-Raf-Mek on the PI3K pathway and the known feedback mechanisms of activation have prompted the use of compounds with broader effect at multiple levels and rational combination strategies to obtain a more potent antitumor activity and possibly a meaningful clinical effect. Here, we review the biology of the network, its role in the development and progression of breast cancer, and the evaluation of targeted therapies in clinical trials.