A phase Ib trial of pembrolizumab plus paclitaxel or flat-dose capecitabine in 1st/2nd line metastatic triple-negative breast cancer

Chemoimmunotherapy with anti-programmed cell death 1/ligand 1 and cytotoxic chemotherapy is a promising therapeutic modality for women with triple-negative breast cancer, but questions remain regarding optimal chemotherapy backbone and biomarkers for patient selection. We report final outcomes from a phase Ib trial evaluating pembrolizumab (200 mg IV every 3 weeks) with either weekly paclitaxel (80 mg/m² weekly) or flat-dose capecitabine (2000 mg orally twice daily for 7 days of every 14-day cycle) in the 1st/2nd line setting. The primary endpoint is safety (receipt of 2 cycles without grade III/IV toxicities requiring discontinuation or ≥21-day delays). The secondary endpoint is efficacy (week 12 objective response). Exploratory aims are to characterize immunologic effects of treatment over time, and to evaluate novel biomarkers. The trial demonstrates that both regimens meet the pre-specified safety endpoint (paclitaxel: 87%; capecitabine: 100%). Objective response rate is 29% for pembrolizumab/paclitaxel (n = 4/13, 95% CI: 10-61%) and 43% for pembrolizumab/capecitabine (n = 6/14, 95% CI: 18-71%). Partial responses are observed in two subjects with chemo-refractory metaplastic carcinoma (both in capecitabine arm). Both regimens are associated with significant peripheral leukocyte contraction over time. Response is associated with clinical PD-L1 score, non-receipt of prior chemotherapy, and the H&E stromal tumor-infiltrating lymphocyte score, but also by a novel 27 gene IO score and spatial biomarkers (lymphocyte spatial skewness). In conclusion, pembrolizumab with paclitaxel or capecitabine is safe and clinically active. Both regimens are lymphodepleting, highlighting the competing immunostimulatory versus lymphotoxic effects of cytotoxic chemotherapy. Further exploration of the IO score and spatial TIL biomarkers is warranted. The clinical trial registration is NCT02734290.

Abstract OT1-19-01: A Single Arm Phase 2 Study of Peri-Operative Checkpoint-Mediated Immune Therapy and Cryoablation in Women with Hormone Receptor-Negative, HER2-Negative Early Stage/Resectable Breast Cancer

Background: Local tumor destruction with cryoablation (cryo) induces inflammation and releases antigens that can activate tumor-specific immune responses. Pre-clinically, cryo with immune checkpoint inhibition (ICI)-augmented tumor-specific immune responses and prevented recurrence. Clinically, we established that peri-operative (peri-op) cryo with ipilimumab (ipi) +/- nivolumab (nivo) was not only safe in patients (pts) with operable, early stage breast cancer (ESBC) but also generated robust intra-tumoral and systemic immune responses. In this phase 2 study, we evaluate the disease specific impact of peri-op ICI in women with residual triple negative breast cancer (TNBC) after neoadjuvant chemotherapy (NAC), a subset at high risk of early relapse. Methods: Eligible pts are ≥18y, with ER < 10%, PR < 10%, HER2 negative (per ASCO/CAP definition), ≥ 1.0 cm, residual operable disease after taxane-based NAC. Approximately 80 pts will be enrolled and treated with ipi/nivo/cryo followed by breast surgery and adjuvant nivo across multiple institutions. Pts undergo percutaneous, image-guided cryo with concurrent research core biopsy 7-10 days prior to surgery and will receive ipi (1mg/kg IV) with nivo (240mg IV) 1 to 5 days prior to cryo. After surgery, pts will receive 3 additional doses of nivo at 240mg IV Q2 weeks. Adjuvant capecitabine is recommended for all patients per local standard-of-care. Patients will be stratified by NAC platinum administration, NAC anthracycline administration, and clinical nodal status (positive versus negative). The primary endpoint is 3-year Event Free Survival (EFS). Secondary endpoints include Invasive Disease-Free Survival (IDFS), Distant Disease-Free Survival (DDFS), overall survival (OS) and safety. Exploratory correlative studies will be performed on tumor and serum to characterize the immunologic impact of the intervention and to explore predictors of efficacy and toxicity. Funding sources: Susan G. Komen, ASCO Conquer Cancer Foundation, Breast Cancer Research Foundation, Bristol-Myers Squibb, BTG International Ltd. NCT03546686

Citation Format: Heather McArthur, Elizabeth Comen, Yolanda Bryce, Stephen Solomon, Jorge Henrique Santos Leal, Christina DiLauro Abaya, Cristal Martinez, Reva Basho, Dorothy Park, Philomena McAndrew, Brigid Larkin, William Mills, David B. Page, Staci Mellinger, Nicole Fredrich, Nicole Moxon, Sangeetha Reddy, Meredith Carter, Sujata Patil, Larry Norton. A Single Arm Phase 2 Study of Peri-Operative Checkpoint-Mediated Immune Therapy and Cryoablation in Women with Hormone Receptor-Negative, HER2-Negative Early Stage/Resectable Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT1-19-01.

Abstract OT2-20-01: Neoadjuvant survivin immunotherapy maveropepimut-S (MVP-S) to increase Th1 immune response in Ki67-high hormone receptor positive (HR+) early-stage breast cancer

Background: HR+ early stage breast cancer (ESBC) is associated with suboptimal pathologic complete response rate (pCR, ~10%) following neoadjuvant cytotoxic chemotherapy. Neoadjuvant endocrine therapy with aromatase inhibitors (AI) may serve as an effective alternative as gauged using the surrogate Ki67 cell proliferation histologic marker. Patients with poor Ki67 response (defined as Ki67>10%) following neoadjuvant AI exhibit poor prognosis and therapeutic resistance to both endocrine therapy and chemotherapy. In a genomic analysis of Ki67-high HR+ tumors, we identified 8-fold upregulation of BIRC5 (survivin), a gene that regulates apoptosis and the cell cycle and is associated with poor clinical outcome. Maveropepimut-S (MVP-S) leverages the non-aqueous, lipid-based DPX delivery platform to educate a specific and persistent T cell-based immune response to 5 HLA-restricted peptides from Survivin. Treatment with MVP-S and intermittent, low-dose cyclophosphamide (CPA) has shown to increase tumor infiltration of survivin-specific T cells. Previous clinical trials have shown that MVP-S is well-tolerated, immunogenic, and could lead to clinical response in several cancer indications. Further exploration of the regimen in breast cancer could extend the application of this immunotherapy for the unmet medical need of improving clinical response in high ki67 HR+ ESBC prior to surgery. Trial Design: NCT04895761 is phase I trial evaluating the safety and immunologic effects of neoadjuvant MVP-S plus letrozole (arm A, n=6), with/without tumor-directed MR-guided radiotherapy (arm B, n=6), or intermittent low-dose cyclophosphamide (CPA, arm C, n=6). Postmenopausal patients with T1c+ HR+HER2- breast cancer with Ki67>10% will receive two doses of MVP-S and 7 weeks of neoadjuvant letrozole prior to surgery (all arms), arm B will be treated additionally with concurrent 10Gy x 2 tumor boost radiation to facilitate immunogenic cell death, and arm C (n=6) will be treated additionally with intermittent low-dose CPA (50mg BID) to facilitate regulatory T cell depletion. Specific Aims: The primary objective is safety. Biomarker objectives are to evaluate for each treatment arm: 1) systemic type I survivin-specific immune response, as measured by IFN-γ ELISPOT; 2) changes in immune environment by GeoMx digital spatial genomic profiling; 3) and changes in tumor infiltrating lymphocytes (TILs) and Ki67. These data will be used to identify the most immunogenic MVP-S combination therapy for study in phase II trial powered to assess clinical outcome (pCR). Accrual: 3 of 6 patients in the MVP-S+ letrozole arm have been enrolled. Arm B and C will enroll after completion of arm A.

Citation Format: Sasha E. Stanton, Lisa D. MacDonald, Stephan Fiset, Staci Mellinger, Nicole Moxon, Heather Hirsch, Tracy L. Kelly, Kristina H. Young, David B. Page. Neoadjuvant survivin immunotherapy maveropepimut-S (MVP-S) to increase Th1 immune response in Ki67-high hormone receptor positive (HR+) early-stage breast cancer. [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT2-20-01.

A single-arm, phase 2 study of perioperative ipilimumab, nivolumab, and cryoablation in women with hormone receptor-negative, HER2-negative, early-stage/resectable breast cancer

TPS617

Background: Local tumor destruction with cryoablation (cryo) induces inflammation and releases antigens that can activate tumor-specific immune responses. Pre-clinically, cryo with checkpoint inhibition augmented tumor-specific immune responses and prevented recurrence. Clinically, we established that peri-operative (peri-op) cryo with ipilimumab (ipi) +/- nivolumab (nivo) was not only safe in patients (pts) with operable, early stage breast cancer (ESBC) but also generated robust intra-tumoral and systemic immune responses. In this phase 2 study, we evaluate the disease specific impact of peri-op ipi/nivo/cryo in women with residual triple negative breast cancer (TNBC) after neoadjuvant chemotherapy (NAC), a subset at high risk of early relapse. Methods: Eligible pts are ≥18y, with ER < 10%, PR < 10%, HER2 negative (per ASCO/CAP definition), ≥ 1.0 cm, residual operable disease after taxane-based NAC. Approximately 80 pts will be enrolled and treated with ipi/nivo/cryo followed by breast surgery and adjuvant nivo. Pts undergo percutaneous, image-guided cryo with concurrent research core biopsy 7-10 days prior to surgery and will receive ipi (1mg/kg IV) with nivo (240mg IV) 1 to 5 days prior to cryo. After surgery, pts will receive 3 additional doses of nivo at 240mg IV Q2 weeks. Adjuvant capecitabine is recommended for all patients per local standard-of-care. Patients will be stratified by NAC platinum administration, NAC anthracycline administration, and clinical nodal status (positive versus negative). The primary endpoint is 3-year Event Free Survival (EFS). Secondary endpoints include Invasive Disease-Free Survival (IDFS), Distant Disease-Free Survival (DDFS), overall survival (OS) and safety. Exploratory correlative studies will be performed on tumor and serum to characterize the immunologic impact of the intervention and to explore predictors of efficacy and toxicity. Clinical trial information: NCT03546686.

Neoadjuvant survivin-targeted immunotherapy maveropepimut-S (MVP-S) to increase Th1 immune response in Ki67-high hormone receptor-positive (HR+) early-stage breast cancer (ESBC)

TPS1119

Background: HR+ ESBC is associated with suboptimal pathologic complete response rate (pCR, ̃10%) following neoadjuvant cytotoxic chemotherapy. Neoadjuvant anti-endocrine therapy with aromatase inhibitors (AI) may serve as an effective alternative. Efficacy can be gauged using the surrogate Ki67 cell proliferation histologic marker. Patients with poor Ki67 response (defined as Ki67 > 10%) following neoadjuvant AI exhibit poor prognosis and therapeutic resistance to both anti-endocrine therapy and chemotherapy. In a genomic analysis among Ki67-high HR+ tumors, we identified 8-fold upregulation of BIRC5 (survivin), a gene that regulates apoptosis and the cell cycle and that is associated with poor clinical outcome. Maveropepimut-S (MVP-S, previously named DPX-Survivac) leverages the non-aqueous, lipid-based DPX delivery platform to educate a specific and persistent T cell-based immune response to 5 HLA-restricted peptides from Survivin, a cancer-associated protein commonly upregulated in several cancers. Treatment with MVP-S and intermittent, low-dose cyclophosphamide (CPA) has shown tumor infiltration of survivin-specific T cells. Previous clinical trials have shown that MVP-S is well-tolerated, immunogenic, and could lead to clinical response in several cancer indications. Further exploration of the regimen in breast cancer could extend the application of this immunotherapy for this unmet medical need. Methods: NCT04895761 is phase I trial evaluating the safety and immunologic effects of neoadjuvant MVP-S plus letrozole (arm A, n = 6), with/without tumor-directed MR-guided radiotherapy (arm B, n = 6), or intermittent low-dose cyclophosphamide or CPA (arm C, n = 6). Postmenopausal patients with T1c+ HR+HER2- breast cancer with Ki67 > 10% will receive two doses of MVP-S and 7 weeks of neoadjuvant letrozole prior to surgery (all arms), whereas arm B will be treated additionally with concurrent 10Gy x 2 tumor boost radiation to facilitate immunogenic cell death, and arm C (n = 6) will be treated additionally with intermittent low-dose CPA (50mg BID) to facilitate regulatory T cell depletion. The primary objective is safety. Biomarker objectives are to evaluate for each treatment arm: 1) systemic type I survivin-specific immune response, as measured by IFN-γ ELISPOT; 2) changes in immune environment by GeoMx digital spatial genomic profiling; 3) and changes in tumor infiltrating lymphocytes (TILs) and Ki67. These data will be used to identify the most immunogenic MVP-S combination therapy for study in phase II trial powered to assess clinical outcome (pCR). Clinical trial information: NCT04895761.

Association of 27-gene IO score with outcome in a phase Ib trial of pembrolizumab (pembro) plus chemotherapy (CT) in metastatic triple-negative breast cancer (mTNBC)

1082

Background: The IO score is a is a 27-gene signature developed to classify the tumor immune microenvironment derived from the 101-gene TNBCtype genomic classifications. The IO score predicts clinical outcome following immune checkpoint inhibitor therapy in NSCLC and bladder cancer, and recently was shown to predict benefit by pCR of atezolizumab plus CT over neoadjuvant CT alone in early stage TNBC (NeoTRIPaPDL1 trial). The IO score has not yet been evaluated in mTNBC or with pembro in breast cancer. Methods: We report preliminary associations of IO score with response from a phase Ib trial (NCT02734290). mTNBC subjects received 1st/2nd line pembro (200mg IV q3wk) plus investigator’s choice paclitaxel (80mg/m2 IV q1wk, n = 15) or capecitabine (2000mg PO BID x 7d, q2wk, n = 14). Baseline (n = 23) and on-treatment (at wk 6, n = 10) biopsies were analyzed for IO score and genomic subtype by RNA exome sequencing. Objective response rate (ORR, partial or complete response, 12 weeks) and survival was determined among response-evaluable subjects (n= 21). Tumor PD-L1 was assessed by IHC (combined positive score, CPS > 10%). The IO signature was analyzed as a binary classifier (IO+/IO-) and as a continuous variable (IO score). Results: 39% of evaluable subjects were IO+ (n =9/23). IO+ was associated with improved clinical outcome, including ORR (IO+ 43%, IO- 29%), median progression free survival (mPFS, IO+ 138d, IO- 79d), and median overall survival (mOS, IO+ 687d, IO- 305d). IO+/IO- classification and IO scores were stable across serial biopsies (Cohen’s kappa = 0.74, r = 0.84). IO score was not strongly correlated with PD-L1 CPS (r = 0.27) or sTILs (r =.09). PD-L1-/IO+ tumors constituted 31% (n = 5/16) of PD-L1- cases and exhibited favorable outcome (ORR 40%, mPFS 162d, mOS 556d). IO score and ORR varied across TNBCtype classifications (BL1 subtype: 50% ORR, 66% IO+; BL2 subtype: 0% ORR, 66% IO+; LAR subtype: 50% ORR, 0% IO+, MSL subtype: 33% ORR, 60% IO+). Conclusions: IO score is associated with favorable outcome following pembro + CT, and may identify PD-L1-negative cases that respond to pembro + CT. Further investigation in larger datasets is warranted to ascertain the clinical utility of IO score in this setting. Funding: Drug support and funding provided by Merck Sharpe & Dohme as part of the Merck Investigator Studies Program. Clinical trial information: NCT02734290.

Abstract OT1-18-03: The neoIRX trial:locoregional cytokine therapy to promote immunologic priming and enhanced response to neoadjuvant pembrolizumab plus chemotherapy in triple negative breast cancer (TNBC)

Background: In stage II/III TNBC, pembrolizumab when combined with chemotherapy (doxorubicin, cyclophosphamide, paclitaxel [ACT], and carboplatin) improves event free survival and pathologic complete response (pCR) rate (Keynote-522 study).1 Novel combination immunotherapy strategies may further improve outcome and/or afford the opportunity to de-escalate the chemotherapy backbone. We have previously reported safety and feasibility of pre-operative IRX-2, a novel cytokine-based therapeutic that can be administered locoregionally to enhance immune response.2 In a phase Ib study in stage I-III breast cancer, IRX-2 was safe, well tolerated, and associated with increased tumor infiltrating lymphocytes (sTILs, by H&E and multispectral immunofluorescence [mIF]), PD-L1 expression (Ventana SP142 assay, mIF), and lymphocyte activation (by RNA sequencing). These potential immunomodulatory effects support further study of IRX-2 in combination with ICI and chemotherapy in the neoadjuvant setting. Methods: Patients are randomized to a phase II, open-label trial to evaluate the clinical and immunological activity of pembrolizumab plus de-escalated chemotherapy (ACT) when combined with IRX-2 for TNBC. All patients (n=30) will receive pembrolizumab induction (single dose 200mg IV), followed by pembrolizumab every three 3 weeks in conjunction with ACT as neoadjuvant therapy prior to surgery. Patients randomized to arm A (n=15) will additionally receive peri-lymphatic locoregional injections of IRX-2 (1mL SQ x 2 daily, x 10 days) during the induction phase. Eligible subjects will have previously untreated, resectable stage II/III TNBC. The primary endpoint is pCR. The secondary endpoint is safety. On-treatment biopsies following induction (pembrolizumab +/- IRX-2) will permit a prospective, randomized validation of previously reported immunomodulatory effects of IRX-2 (sTILs, PD-L1, lymphocyte RNA signatures). As of 7/8/2021, n=6/30 subjects are enrolled (Providence Cancer Institute, Portland, OR, Providence St. John’s Cancer Institute, Santa Monica, CA, Baylor College of Medicine, Houston, TX). NCT04373031. 1Schmid, P. N Engl J Med 2020; 382:810-821. 2Page, DB. Clin Cancer Res 2020; 26.7:1595-1605.

Citation Format: Katherine Sanchez, Alison Conlin, Parvin Peddi, Sasha Stanton, Janet Ruzich, Kelly Perlewitz, Yaping Wu, Nicole Moxon, Staci Mellinger, Zhaoyu Sun, William Redmond, David B Page. The neoIRX trial:locoregional cytokine therapy to promote immunologic priming and enhanced response to neoadjuvant pembrolizumab plus chemotherapy in triple negative breast cancer (TNBC) [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 OT1-18-03.

Abstract OT1-18-04: A phase II study of dual immune checkpoint blockade (ICB) plus bicalutamide to enhance thymic T-cell production and immunotherapy response in metastatic breast cancer (MBC)

Background: The addition of anti-programmed death 1/ligand 1 (anti-PD-1/L1) improves progression-free survival when combined with chemotherapy in PD-L1-positive triple-negative MBC. However, novel combination therapies are needed to improve efficacy in hormone receptor positive (HR+) MBC, or in patients with PD-L1-negative disease. Dual ICB with nivolumab (anti-PD-1) and ipilimumab (anti-CTLA-4) has not been studied in depth in MBC despite its success in other solid tumors. Furthermore, MBCs often express the androgen receptor (AR), which can be targeted therapeutically. AR blockade agents have been shown to stimulate thymic production of naïve T-cell clones. It is proposed that ICB in conjunction with AR blockade may facilitate thymopoeisis and subsequent activation of novel, tumor-reactive T-cell clones. Trial design: This is a phase II, open-label trial investigating the combination of ICB (nivolumab 240mg IV q2w; ipilimumab 1mg/kg IV q6w) and AR blockade (bicalutamide, 150mg PO daily) in MBC. Two cohorts will be studied: AR-positive TNBC [ &gt; 1% by IHC, constituting ~50% of TNBCs]; and HR+ MBC (of which the great majority are AR-positive). Eligibility: Patients must have RECIST1.1 measurable disease, ECOG performance score 0-1, and adequate hematological and hepatic function. Subjects may have received no more than 1 prior non-curative chemotherapy. Specific aims: Subjects will be assessed for clinical benefit by iRECIST criteria and safety by CTCAE v4.0, with clinical efficacy defined as &gt;20% improvement in week 24 clinical benefit rate, over historical control (30% per EMBRACE clinical trial). Statistical analysis will be performed by a Simon 2-stage design to minimize futility (n = 46/cohort, stage I: n = 15). As exploratory aims, thymic generation of T-cells will be measured via quantitative deep sequencing of T-cell receptors (TcR, ImmunoSEQ assay), TcR excision circles (TRECs), and flow cytometry using markers of recent thymic emigration. Present accrual: As of 7/8/2021, n=19 subjects are enrolled (4 TNBC, 15 HR+). The trial is open at Providence Cancer Institute (Portland, OR) and Memorial Sloan Kettering Cancer Center (New York, NY). Target accrual: stage I: n=15 per arm; a maximum of 138 patients (46 per cohort) may be enrolled in expansion cohorts. Contact: Dr. David Page (David.page2@providence.org) Clinicaltrials.gov#: NCT03650894

Citation Format: David B Page, Krystle L Collins, Brie Chun, Zhaoyu Sun, William L Redmond, Maritza Martel, Yaping Wu, Nicole Moxon, Staci L Mellinger, Walter J Urba, Tiffany A Traina, Ayca Gucalp. A phase II study of dual immune checkpoint blockade (ICB) plus bicalutamide to enhance thymic T-cell production and immunotherapy response in metastatic breast cancer (MBC) [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 OT1-18-04.

399 A phase II study of nivolumab, ipilimumab, plus androgen receptor blockade with bicalutamide to enhance thymic T-cell production and immunotherapy response in metastatic breast cancer

Background

It has previously been shown that immune checkpoint blockade (ICB) with anti-programmed death 1/ligand 1 (anti-PD-1/L1) improves survival when combined with chemotherapy in PD-L1-positive first-line triple-negative metastatic breast cancer (MBC). Given the lower efficacy of ICB in hormone receptor positive (HR+) or PD-L1-negative disease, and in later lines of therapy, novel combinations are necessary. Dual ICB with nivolumab (anti-PD-1) and ipilimumab (anti-CTLA-4) has shown success in other solid tumors but has not been extensively studied in MBC. Furthermore, MBCs often express the androgen receptor (AR), which can be targeted to modulate immune response. AR blockade may stimulate thymic production of naïve T-cell clones by modulating the Notch pathway,1 whereas ICB can amplify the immune activity of recent thymic emigrants by blocking PD-1-mediated peripheral tolerance.2

Methods

This is an open-label, Simon 2-stage phase II trial investigating the dual ICB (nivolumab 240mg IV q2w; ipilimumab 1mg/kg IV q6w) and AR blockade (bicalutamide, 150mg PO daily) in MBC. Two cohorts will be studied: AR-positive TNBC [ > 1% by IHC, constituting ~50% of TNBCs]; and HR+ MBC (of which the great majority are AR-positive). Eligible patients must have RECIST1.1 measurable disease, Eastern Cooperative Oncology Group performance score 0 or 1, adequate hematological/hepatic function, and received no more than 1 prior course of non-curative chemotherapy. Target accrual is n=15 per arm (stage I), with a maximum of 46 patients per cohort. Current cohort accrual n=15 HR+ and n=5 TNBC. The primary endpoint is week 24 clinical benefit by iRECIST criteria, with success defined as >20% improvement over historical control (30% per EMBRACE clinical trial).3 Safety will be evaluated by CTCAE v4.0. Biomarkers of recent thymic activation will be evaluated via quantitative deep sequencing of T-cell receptors (TcR, ImmunoSEQ assay), TcR excision circles (TRECs), and flow cytometry using markers for recent thymic emigration (CD3+CD45RA+CD45RO-CD31+)

Trial Registration

NCT03650894. The trial is open at Providence Cancer Institute (Portland, OR) and Memorial Sloan Kettering Cancer Center (New York, NY).

References

Velardi E, Tsai JJ, Holland AM, et al. Sex steroid blockade enhances thympoesis modulating notch signaling. J Exp Med 2014;211(12):2341–49.

Thangavelu G, Parkman JC, Ewen CL, et al. Programmed death-1 is required for systemic self-tolerance in newlygenerated T cells during the establishment of immune homeostasis. Journal of autoimmunity 2011;36(3–4):301–12.

Kaufman PA, Awada A, Twevles C, et al. Phase III open-label randomized study of eribulin mesylate versus capecitabine in patients with locally advanced or metastatic breast cancer previously treated with an anthracycline and a taxane. J Clin Oncol 2015;33(6):594–601.

Ethics Approval

This study was approved by the IRB department and Providence Portland Medical Center, Clinical Trials Department for study NCT03650894.

Consent

Written, informed consent is obtained from each participant.

398 neoIRX: a phase II trial of locoregional cytokine therapy to promote immunologic priming and clinical response to neoadjuvant pembrolizumab plus chemotherapy in triple negative breast cancer (TNBC)

Background

Background: The FDA has approved pembrolizumab in combination with neoadjuvant chemotherapy (doxorubicin, cyclophosphamide, paclitaxel [ACT], and carboplatin) for stage II/III TNBC, on the basis of improved event free survival (EFS) and pathologic complete response (pCR) rate in the Keynote-522 study.1 Novel combination immunotherapy strategies may further improve outcomes and allow the opportunity to de-escalate the chemotherapy backbone, potentially mitigating grade III/IV toxicities which occurred in 81% of recipients. We have previously reported safety and feasibility of pre-operative IRX-2, a novel cytokine biotherapeutic, that is administered locoregionally in the peri-areolar tissue to enhance the immune microenvironment within the sentinel lymph nodes, the putative site of antigen presentation.2 In this phase Ib study, pre-operative IRX-2 was safe and was associated with increased tumor infiltrating lymphocytes (sTILs, by H&E and multispectral immunofluorescence [mIF]), PD-L1 expression (Ventana SP142 assay, mIF), and lymphocyte activation (by RNA sequencing). Similar effects were observed in a pre-operative head and neck carcinoma trial. These findings support further study of IRX-2 in combination with anti-PD-1 in early stage TNBC.

Methods

Methods

neoIRX is an open-label, phase II trial to evaluate the clinical and immunological activity of induction IRX-2 plus pembrolizumab, followed by de-escalated chemotherapy (ACT) and pembrolizumab as neoadjuvant therapy in TNBC. Patients are randomized to receive pembrolizumab induction (single dose 200mg IV, n=15), versus pembrolizumab + IRX-2 induction (1mL SQ x 2 daily, x 10 days, n=15), followed by research biopsy. All patients will then receive neoadjuvant pembrolizumab plus ACT every three 3 weeks. Eligible subjects will have previously untreated, resectable stage II/III TNBC. The primary endpoint is pCR. The secondary endpoint is safety. On-treatment biopsies will permit a prospective, randomized validation of previously reported immunomodulatory effects of IRX-2 (sTILs, PD-L1, lymphocyte RNA signatures). As of 7/28/2021, n=7/30 subjects are enrolled (Providence Cancer Institute, Portland, OR, Providence St. John’s Cancer Institute, Santa Monica, CA, Baylor Medicine, Houston, TX).

Trial Registration

NCT04373031

References

Schmid PN. Engl J Med 2020; 382:810–821.

Page DB. Clinical Cancer Research 26.7(2020):1595–1605.

Ethics Approval

The study protocol was approved by the Providence Portland Medical Center IRB committee and was conducted in accordance with the ethical standards established by the Declaration of Helsinki, PH&S IRB# 2019000486. Written informed consent was obtained for all trial participants.

A Phase Ib Study of Preoperative, Locoregional IRX-2 Cytokine Immunotherapy to Prime Immune Responses in Patients with Early-Stage Breast Cancer

PURPOSE

To evaluate the safety and feasibility of preoperative locoregional cytokine therapy (IRX-2 regimen) in early-stage breast cancer, and to evaluate for intratumoral and peripheral immunomodulatory activity.

PATIENTS AND METHODS

Sixteen patients with stage I-III early-stage breast cancer (any histology type) indicated for surgical lumpectomy or mastectomy were enrolled to receive preoperative locoregional immunotherapy with the IRX-2 cytokine biological (2 mL subcutaneous × 10 days to periareolar skin). The regimen also included single-dose cyclophosphamide (300 mg/m²) on day 1 to deplete T-regulatory cells and oral indomethacin to modulate suppressive myeloid subpopulations. The primary objective was to evaluate feasibility (i.e., receipt of therapy without surgical delays or grade 3/4 treatment-related adverse events). The secondary objective was to evaluate changes in stromal tumor-infiltrating lymphocyte score. The exploratory objective was to identify candidate pharmacodynamic changes for future study using a variety of assays, including flow cytometry, RNA and T-cell receptor DNA sequencing, and multispectral immunofluorescence.

RESULTS

Preoperative locoregional cytokine administration was feasible in 100% (n = 16/16) of subjects and associated with increases in stromal tumor-infiltrating lymphocytes (P < 0.001). Programmed death ligand 1 (CD274) was upregulated at the RNA (P < 0.01) and protein level [by Ventana PD-L1 (SP142) and immunofluorescence]. Other immunomodulatory effects included upregulation of RNA signatures of T-cell activation and recruitment and cyclophosphamide-related peripheral T-regulatory cell depletion.

CONCLUSIONS

IRX-2 is safe in early-stage breast cancer. Potentially favorable immunomodulatory changes were observed, supporting further study of IRX-2 in early-stage breast cancer and other malignancies.

Pembrolizumab (pembro) with paclitaxel (taxol) or capecitabine (cape) as early treatment of metastatic triple-negative breast cancer (mTNBC)

1015

Background: Atezolizumab (anti-PD-L1) plus nab-paclitaxel was shown to improve outcomes in mTBNC in a phase III clinical trial. Subjects were required to be > 12 months from curative-intent therapy in this trial. It remains unknown whether non-taxane chemo + anti-PD-1/L1 will be beneficial in mTNBC, or whether this approach is effective in rapidly-progressing patients ( < 12 mo from curative-intent therapy). Methods: mTNBC patients were enrolled in a phase Ib study of anti-PD-1 (pembro, 200mg IV q3w) plus physician’s choice chemo (cape: n = 14, 2000mg BID, 7d on/7d off; or taxol: n = 14, 80mg/m2 q1w). Primary/secondary objectives were to evaluate safety/tolerability (primary) and RECIST1.1 response (w12). The exploratory objective was to explore for differences in immunomodulation according to chemo choice. Mixed effects models were employed to compare the longitudinal effects of chemo on peripheral immune cells (flow cytometry) and T-cell diversity (Immunoseq assay). Results: Enrollment of the trial is complete (n = 28), with 100% of evaluable patients tolerating therapy (n = 22) as of 2/1/2019. Cape ORR was 43% (5 PR, 1 CR, 2 SD) with median PFS = 155d. Taxol ORR was 25% (1 CR, 1 PR, 3 SD) with median PFS = 99d. Subjects enrolled < 12 months from curative-intent therapy had numerically lower response (ORR = 27%, 1 CR, 2 PR, 3 SD) than subjects without rapid progression (ORR = 45%, 1 CR, 4 PR, 2 SD). No significant differences in immunomodulation were observed according to chemo type, however both cape & taxol were associated with declines in T-cell quantity (CD4 p < .02, CD8 p < .04) and Immunoseq T-cell fraction over time. Conclusions: Pembro plus cape or taxol is safe with encouraging efficacy, however activity may be lower in the setting of rapid progression following curative-intent chemo. Cape+pembro efficacy is favorable with no measurable differences in immunomodulation, and therefore cape may be preferred as a chemo backbone in selected patients. Both cape and taxol are associated with iatrogenic declines in T-cell quantity, which may explain the observed dropoff in anti-PD-1/L1 activity in later lines. Clinical trial information: NCT02734290.

A phase II study of dual immune checkpoint blockade (ICB) plus androgen receptor (AR) blockade to enhance thymic T-cell production and immunotherapy response in metastatic breast cancer (MBC)

TPS1106

Background: ICB (atezolizumab, anti-PD-L1) is known to improve survival when added to chemo, however only in PD-L1-positive, triple-negative MBC. ICB is less effective in hormone receptor positive (HR+) MBC, or when administered following palliative chemo. Novel approaches are required to broaden clinical benefit of ICB, particularly in PD-L1-negative, HR+, or chemo-experienced MBC. Dual ICB with anti-PD-1 (nivolumab) and anti-CTLA-4 (ipilimumab) is associated with enhanced activity in melanoma other malignancies, but has not been explored extensively in MBC. Androgen receptor (AR) blockade, in addition to known direct cytostatic effects in AR-expressing MBCs (50% of TNBC, > 75% of HR+ MBC), may also modulate immune response. AR blockade has been shown experimentally to stimulate thymic production of naïve T-cell clones, which in turn can facilitate de novo anti-tumor immune responses. Concurrent ICB can enhance the activity of these T-cell clones by interfering with PD-1-mediated peripheral tolerance. This combination approach is promising in MBC in light of known AR positivity, and the routine use of lymphodepleting chemo regimens in the curative-intent setting. Methods: This is a phase II trial of dual immune checkpoint blockade (nivolumab 240mg IV q2w; ipilimumab 1mg/kg IV q6w) plus AR blockade (bicalutamide, 150mg PO daily, dose reduction allowed) in triple-negative MBC (cohort A: AR-positive [ > 1% by IHC]; cohort B: AR-negative) or HR+ MBC (cohort C) in subjects who received 0/1 prior chemotherapies in the non-curative setting. Objectives include 24-week clinical benefit rate by iRECIST (primary), safety (CTCAE v4.0), and other response measures (RECIST1.1, PFS, OS). Efficacy for each cohort is defined as > 20% improvement in response over historical control (30% per EMBRACE clinical trial) employing a Simon 2-stage design to minimize futility (n = 46/cohort, stage I n = 15). Thymic generation of T-cells will be measured via quantitative deep sequencing of T-cell receptors (TcR, ImmunoSEQ assay) and TcR excision circles (TRECs), as well as real-time flow cytometry using surrogate cell surface markers of recent thymic emigration. Enrollment has commenced, sites: Earle A. Chiles Research Institute (Portland, OR), Memorial Sloan Kettering Cancer Center (New York, NY). Clinical trial information: NCT03650894.

Abstract P2-09-12: Perilymphatic IRX-2 cytokine therapy to enhance tumor infiltrating lymphocytes (TILs) and PD-L1 expression preceding curative-intent therapy in early stage breast cancer (ESBC)

Background: Cytokines are being explored as a therapeutic strategy to modulate the tumor microenvironment and facilitate immunotherapy benefit in breast cancer. Here, we investigate a locoregional therapeutic approach whereby cytokines (IRX-2) are administered into the subcutaneous peri-areolar tissue (in an anatomic distribution similar to sentinel lymph node mapping) to facilitate immune cell recruitment/activation within the draining lymph nodes and tumor in ESBC. IRX-2 is derived from ex vivo phytohemagglutinin-stimulated lymphocytes and contains multiple cytokines including IL-1β, IL-2, TNF-α, IFN-γ, IL-6, IL-8, and GM-CSF, with stable concentrations from lot to lot. Preclinically, IRX-2 activates T-cells and natural killer (NK) cells, facilitates antigen presentation, and enhances activity of anti-PD-1/L1 in a SCC7 model. In a preceding head/neck squamous cell carcinoma phase I trial, perilymphatic IRX-2 was safe and increased TILs. Here, we report the final clinical results of a phase Ib trial evaluating the feasibility and immunologic activity of IRX-2 in ESBC.

Methods: Beginning 21 days prior to surgical resection, enrolled operable patients with stage I-III ESBC (all subtypes) received the pre-operative IRX-2 regimen consisting of a single low-dose cyclophosphamide (300 mg/m2 to facilitate T-regulatory cell depletion), followed by 10 days of subcutaneous peri-areolar IRX-2 injections into the affected breast (1 mL × 2 at tumor axis and at 90°). Endpoints were feasibility (primary endpoint), stromal TIL (sTIL) count (pre-treatment versus post-treatment, blinded average of two pathologist reads using San Antonio H&E sTIL guidelines), PD-L1 expression (Nanostring) and enumeration of peripheral immune cells by flow cytometry.

Results: All patients (n=16/16) completed and tolerated the regimen with no surgical delays or treatment-attributed grade III/IV toxicities. Common adverse events (occurring in &gt;15% subjects) attributed to IRX-2 injections were: injection site reaction (grade 1, n=8/16), bruising (grade 1, n=7/16), and pain (grade 1, n=3/16). Common adverse events attributed to low-dose cyclophosphamide were: fatigue (grade 1, n=5/16) and nausea (grade 1/2, n=3/16). Treatment was associated with an increase in sTIL score (Wilcoxon signed-rank p=.04), with 4/10 sTIL-low tumors (0-10% score) re-categorized to sTIL-moderate (11-50% score). Increases in PD-L1 RNA expression were observed (Wilcoxon signed-rank p=.04) in 12/16 tumors (median 57% increase, range: -53% to 185% increase), as well as increases in Nanostring NK and Th1 cell signatures. In blood, increases in CD4 and CD8 effector T-cell activation (ICOS, HLA-DR, and CD38) and T-reg depletion were observed.

Conclusions: IRX-2 was well tolerated with preliminary evidence of sTIL increase, PD-L1 upregulation, and peripheral lymphocyte activation. Based upon these data and preclinical evaluations demonstrating synergy with checkpoint inhibition, the IRX-2 regimen is being evaluated for clinical efficacy in conjunction with pembrolizumab and neoadjuvant chemotherapy (doxorubicin, cyclophosphamide, paclitaxel) in patients with stage II-III triple negative breast cancer.

Citation Format: Pucilowska J, Egan JE, Berinstein NL, Moxon N, Aliabadi-Wahle S, Imatani JH, Conlin A, Acheson A, Massimino K, Martel M, Campbell M, Wu Y, Sun Z, Redmond W, Shah M, Urba WJ, Page DB. Perilymphatic IRX-2 cytokine therapy to enhance tumor infiltrating lymphocytes (TILs) and PD-L1 expression preceding curative-intent therapy in early stage breast cancer (ESBC) [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 P2-09-12.

Abstract P2-09-03: Updated efficacy of first or second-line pembrolizumab (pembro) plus capecitabine (cape) in metastatic triple negative breast cancer (mTNBC) and correlations with baseline lymphocyte and naïve CD4+ T-cell count

Background: In mTNBC, anti-PD-1/L1 monotherapy is most effective when administered early in the course of disease, with recent trials demonstrating overall response rates (ORR) of 23-26% in the first-line setting and 5-6% in later lines. This may reflect iatrogenic lymphopenia from preceding cytotoxic chemotherapy. Furthermore, curative-intent chemotherapy is associated with prolonged suppression of naïve CD4+ cells, a T-cell subset that may play a critical role in the generation of de novo anti-tumor immune responses. We present the final clinical results of a pilot study evaluating the safety and efficacy of combining pembrolizumab plus standard-of-care capecitabine in the first/second-line mTNBC setting. We also explore potential associations between clinical benefit and lymphopenia, preceding chemotherapy, and absolute naïve CD4+ counts.

Methods: In a pilot study, we evaluated the tolerability and preliminary efficacy of concurrent pembro (200mg IV q21 day) plus investigator-selected 1st/2nd line paclitaxel (80mg/m2 IV weekly) or oral cape (2,000mg BID, weekly 1 on/1 off). The primary endpoint was tolerability, defined as the proportion of subjects receiving &gt;6 weeks concurrent therapy without dose discontinuation with toxicities reported per CTCAE v4.0. The secondary endpoint was 12-week objective response rate (ORR) by RECIST1.1. Exploratory endpoints included peripheral blood cell enumeration by real-time flow cytometry and routine clinical laboratory. Naïve CD4+ cells were defined as CD45+ CD3+ TCRab+ CD4+ CD45RA+ CCR7+. Here, we report the results of the pilot phase of the cape cohort (NCT02734290).

Results: Twelve of 14 subjects were treated in the first-line setting. All subjects (14/14, 100%) tolerated cape+pembro for &gt;6 weeks, with toxicities consistent with monotherapy cape experience (diarrhea: grade I-II 50%, grade III 7%; hand-foot: grade I-II 71%) that improved with dose-reduction as needed. At 12 weeks, the ORR was 6/14 (42.9%), and the clinical benefit rate (ORR + stable disease) was 8/14 (57.1%). Depressed absolute lymphocyte count at baseline (ALC&lt;1.0/uL: 33% CBR; ALC≥1.0/uL: 75% CBR) and recent exposure to cytotoxic chemotherapy (&lt;6 months: 33% CBR; &gt;6 months: 75% CBR) were associated with reduced clinical benefit. By flow cytometry, subjects experiencing clinical benefit had higher baseline absolute naïve CD4+ counts (average 283 cells/uL v. 93 cells/uL, p=.069).

Conclusions: This study met the primary endpoint of safety for cape plus pembro in mTNBC, with encouraging clinical activity. These data are supportive of further studies evaluating combination chemotherapy plus anti-PD-1/L1 mTNBC. We observed greater clinical benefit in subjects with non-suppressed ALC, less exposure to recent chemo, and higher baseline naïve CD4+ counts, suggesting that iatrogenic immunosuppression can impair response to immune checkpoint therapy in mTNBC. These findings should be confirmed in ongoing randomized trials of immune checkpoint +/- chemotherapy in mTNBC, and should be considered in the design of future clinical trials.

Citation Format: Page DB, Pucilowska J, Bennetts L, Kim I, Sanchez K, Martel M, Conlin A, Moxon N, Mellinger S, Acheson A, Kemmer K, Mitri Z, Vuky J, Ahn J, Abaya C, Manigault T, Basho R, Urba WJ, McArthur HL. Updated efficacy of first or second-line pembrolizumab (pembro) plus capecitabine (cape) in metastatic triple negative breast cancer (mTNBC) and correlations with baseline lymphocyte and naïve CD4+ T-cell count [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 P2-09-03.

Abstract P5-01-12: Breast specific gamma imaging (BSGI) and breast magnetic resonance imaging (MRI): Comparison of sensitivity and specificity in women prior to breast biopsy with BIRADS 4 or 5 finding on mammography in a community setting

Background: Diagnostic imaging following a new diagnosis of breast cancer remains an active area of research balancing value and outcomes. Decisions about surgical options and neo-adjuvant therapy depend greatly on the accuracy of these pre-operative assessments. BMRI use has increased tenfold from 2000 to 2011 (Stout et al, JAMA 2013) and estimation of sensitivity has been high but specificity has varied between 30-80%(Bluemke et al, JAMA 2004). BSGI is a novel molecular imaging technique that uses a gamma camera to track the uptake of a radio tracer (technitium Tc99m sestamibi) by breast cancer cells and has been used interchangeably with BMRI without rigorous evidence of equivalency (Khalkhauli, et al, J Nuc Med 2000).The majority of research into the sensitivity and specificity of these tests has been retrospective, only on women with known cancer, and potentially biased by post-biopsy changes to breast tissue.

Methods: Therefore we performed a prospective study employing both techniques to image women with BIRADS 4 or 5 lesions on diagnostic mammogram prior to their planned breast biopsy. The BSGI and BMRI were reviewed by one of three dedicated breast radiologists and the pathology was reviewed on the biopsy or any additional biopsy/excision by one pathologist. We compared the BSGI and BMRI against the final pathology for sensitivity and specificity. In addition, we surveyed the women for quality of life measures 3 months later.

Results: Between January 2012 and April 2014 we enrolled 74 women (ages 30-80) at 2 NAPBC accredited breast centers located in a community based setting in Portland, OR. The initial diagnostic mammographic studies resulted in 23 women (32%) with BIRADS 4A, 27 (37%) with BIRADS 4B, 8 women with 4C (11%) while 8 women (11%) had BIRADS 5 lesions prompting biopsy. All women were biopsied and 27 (37%) were found to have an invasive or in situ cancer while 5 (7%) had atypical hyperplasia or LCIS found. Sixteen women had additional biopsies performed, outside of the planned area, as a result of BMRI or BSGI, 11 (69%) were based on BMRI findings and 5 (31%) were areas seen on both BMRI and BSGI. In these additional biopsies 5 were in situ or invasive cancer and 2 were contra-lateral cancers, the rest were benign tissue. The sensitivity of BMRI was 84.0% and BSGI was 74.1%. The specificity was found to be 57.8% and 80.4% respectively. One patient withdrew and 3 women did not complete BMRI due to claustrophobia or body habitus.

Quality of life data is still being analyzed.

Conclusions: We report here the sensitivity and specificity of BMRI compared with BSGI in women with BIRADS 4 and 5 breast lesions on diagnostic mammography. Importantly imaging was done before biopsy and therefore not biased by any effect from that procedure. In this study we find BMRI appears to have better sensitivity but lower specificity than BSGI. We also observed that the use of BMRI and/or BSGI prompted 16 extra biopsies of which less than half were additional or contra-lateral cancer. The incorporation of these tests into the evaluation of suspected cancer should consider these findings as well as cost and quality of life.

Citation Format: Alison K Conlin, Nicole Moxon, Helena Hoen, Christina Gougoutas-Fox, Maureen O Baxter, Amy Weinstein, Maritza Martel, Tracy L Kelly, Walter J Urba. Breast specific gamma imaging (BSGI) and breast magnetic resonance imaging (MRI): Comparison of sensitivity and specificity in women prior to breast biopsy with BIRADS 4 or 5 finding on mammography in a community setting [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-01-12.