Patient-Reported Outcomes in OlympiA: A Phase III, Randomized, Placebo-Controlled Trial of Adjuvant Olaparib in gBRCA1/2 Mutations and High-Risk Human Epidermal Growth Factor Receptor 2-Negative Early Breast Cancer

PURPOSE

The OlympiA randomized phase III trial compared 1 year of olaparib (OL) or placebo (PL) as adjuvant therapy in patients with germline BRCA1/2, high-risk human epidermal growth factor receptor 2-negative early breast cancer after completing (neo)adjuvant chemotherapy ([N]ACT), surgery, and radiotherapy. The patient-reported outcome primary hypothesis was that OL-treated patients may experience greater fatigue during treatment.

METHODS

Data were collected before random assignment, and at 6, 12, 18, and 24 months. The primary end point was fatigue, measured with the Functional Assessment of Chronic Illness Therapy-Fatigue scale. Secondary end points, assessed with the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire, Core 30 item, included nausea and vomiting (NV), diarrhea, and multiple functional domains. Scores were compared between treatment groups using mixed model for repeated measures. Two-sided P values <.05 were statistically significant for the primary end point. All secondary end points were descriptive.

RESULTS

One thousand five hundred and thirty-eight patients (NACT: 746, ACT: 792) contributed to the analysis. Fatigue severity was statistically significantly greater for OL versus PL, but not clinically meaningfully different by prespecified criteria (≥3 points) at 6 months (diff OL v PL: NACT: -1.3 [95% CI, -2.4 to -0.2]; P = .022; ACT: -1.3 [95% CI, -2.3 to -0.2]; P = .017) and 12 months (NACT: -1.6 [95% CI, -2.8 to -0.3]; P = .017; ACT: -1.3 [95% CI, -2.4 to -0.2]; P = .025). There were no significant differences in fatigue severity between treatment groups at 18 and 24 months. NV severity was worse in patients treated with OL compared with PL at 6 months (NACT: 6.0 [95% CI, 4.1 to 8.0]; ACT: 5.3 [95% CI, 3.4 to 7.2]) and 12 months (NACT: 6.4 [95% CI, 4.4 to 8.3]; ACT: 4.5 [95% CI, 2.8 to 6.1]). During treatment, there were some clinically meaningful differences between groups for other symptoms but not for function subscales or global health status.

CONCLUSION

Treatment-emergent symptoms from OL were limited, generally resolving after treatment ended. OL- and PL-treated patients had similar functional scores, slowly improving during the 24 months after (N)ACT and there was no clinically meaningful persistence of fatigue severity in OL-treated patients.

Abstract OT2-11-01: A phase 1 study of the novel immunotoxin MT-5111 in patients with HER2+ tumors: interim results

MT-5111 is a 55kD engineered toxin body targeting HER2 in solid tumors that binds to an epitope distinct from trastuzumab and pertuzumab, offering potential combination strategies with other HER2-targeting agents. MT-5111 works by internalizing, self-routing through intracellular compartments to the cytosol, and inducing potent cell-kill via the enzymatic and permanent inactivation of ribosomes. This is a phase 1 study in adults with advanced HER2+ solid tumors. MT-5111 is dosed weekly IV over 30 min in every 21-day cycle until disease progression, unacceptable toxicity, death, or withdrawn consent. The study has dose escalation (Part A) cohorts enrolling patients (pts) with any HER2+ cancer (CA) and expansion (Part B) cohorts for HER2+ breast cancer (BC), Gastric or Gastroesophageal junction adenocarcinoma (GEA), or other HER2+ solid CA. As of 30 June 2022, 42 total pts had enrolled (36 in Part A on 0.5-23 µg/kg/dose, 6 pts with BC in Part B1 on 10 µg/kg/dose). Median age 65 years, 28 (66.78%) pts were female, median of 4 prior systemic and 2 prior HER2-targeting treatment (tx). 17 pts with BC, 6 with biliary CA, 9 with GEA, and 10 with other solid CA have enrolled. Of the 17 BC pts, 15 received ≥ 10 µg/kg/dose. Tx emergent adverse events (TEAEs) have been reported in 40 (95%) pts, and tx-related AEs (TRAE) occurred in 23 (55%) pts. No pt experienced G4-G5 TRAE. G1 troponin elevations were noted in 5 pts without clinical signs of cardiotoxicity (1 pt 6.75 µg/kg, 2 pts 10 µg/kg, 1 pt 17 µg/kg, 1 pt 23 µg/kg). Reversible G1/G2 infusion-related reactions were reported in 2 pts. Tx-related G1-G3 rash was observed in 5 pts (4 pts ≥ 10 µg/kg/dose); maculopapular in 2 pts, acneiform in 1 pt and associated with pruritus in 3 pts. The G3 rash developed one wk after first dose of 23 µg/kg, was declared a DLT, improved with systemic steroid therapy and the pt continued tx at the same dose without recurrence. Best overall response per RECIST thus far is stable disease (SD) in 17 pts, non-CR/non-PD in 1 pt, and progressive disease (PD) in 14 pts. 1 pt had non-CR/non-PD for 30 wks (1 μg/kg, BC); 1 pt had SD for 24wks (10 μg/kg, pancreatic); 1 pt is on tx with SD through 8 cycles (10 μg/kg, BC). Of the 10 BC pts who received ≥ 10 μg/kg/dose, the best response was 5 SD. The mean serum concentration of MT-5111 has increased in a dose-proportional manner starting at 6.75µg/kg/dose (Table 1). The soluble HER2 (sHER2) levels at end of tx were higher compared to baseline in cohorts that received ≤ 4.5µg/kg/dose, but similar or lower in cohorts that received ≥ 6.75µg/kg/dose. Higher MT-5111 doses have been well tolerated and may saturate circulating sHER2, leading to more predictable serum concentrations and tumor penetration. The Cmax in humans at doses ≥6.75 µg/kg/dose is above the in vitro IC50 for high HER2+ cell lines (0.029nM) and at 17 µg/kg/dose, above the IC50 for moderate HER2+ cells (1.6nM). In conclusion, the dose proportionate increase in serum concentration with levels above the in vitro IC50 and the leveling off/reduction of sHER2 indicate exposure to MT-5111 is at clinically therapeutic levels. Skin toxicity at higher doses may indicate on-target effect as observed in other EGFR-targeted therapies where it is associated with clinical response and a better prognosis. sHER2 biomarker data is expected for all cohorts with PK correlation and 23µg/kg safety and efficacy data.

PK profile of MT-5111, C1D1 values

Citation Format: Meena Okera, Brian A. Van Tine, Joleen M. Hubbard, Minal Barve, Erika Hamilton, Monica M. Mita, Frances Valdes-Albini, Daniel Ahn, Admasu Mamuye, Joshua Pelham, Amy Yuet, Diana Yurewicz, Yanning Liu, Andres Machado Sandri, William J. Edenfield, Aki Morikawa, William Gradishar, Rajiv Kumar, Zev A. Wainberg. A phase 1 study of the novel immunotoxin MT-5111 in patients with HER2+ tumors: interim results [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 OT2-11-01.

Abstract P2-07-05: Activation of the AKT/mTOR signaling pathway is associated with response to the combination of endocrine therapy and CDK4/6 inhibitor in HR+/HER2- metastatic breast cancer

Background: As part of a multicenter study designed to identify markers of response or resistance to the combination of endocrine therapy (ET) and a cyclin dependent kinase 4/6 inhibitor (CDK 4/6i) as standard 1st-line therapy in patients with hormone receptor-positive, HER2-negative (HR+/HER2-), metastatic breast cancer (MBC), we assessed whether pretreatment levels of expression and phosphorylation of CDK 4/6 substrates and downstream molecules can predict response to this treatment. We then conducted an exploratory analysis to identify kinase-driven, pathway-centered mechanisms associated with response in pretreatment tumor samples. Methods: Tumor epithelia were isolated and enriched from the surrounding microenvironment using laser capture microdissection followed by downstream analysis using the Reverse Phase Protein Microarray (RPPA). Unmodified or post-transitionally modified residues were measured for 120 signaling proteins including 8 pre-specified qualifying proteins/phosphoproteins that are direct substrates of CDK 4/6 or whose activity is controlled by CDKI 4/6 activation as predictive markers of response to ET plus a CDK4/6i as 1st-line treatment in HR+/HER2- MBC. These 8 qualifying markers were: total Rb, phospho-Rb (S780), total Cyclin D1, phospho-Cyclin D1 (S286), total p16INK, total p27KIP, phospho-p27KIP (T187), and phospho-FOXM1 (T600). A total of 20 samples were available for the exploratory analysis. Specimens with expression or phosphorylation of the 120 biomarkers above or below the population median were classified as high or low, respectively. Chi-square analysis was used to compare proportion of patients with high and low expression between responders (CR, PR, or SD for a minimum of 12 months) and non-responders (PD within 12 months). Results: Pretreatment phosphorylation levels of Rb at the S780 residue were higher in non-responders compared to responders (p=0.025) and a similar trend was also detected for unmodified Rb, FoxM1 (T600), p27 Kip1 (T187), and Cyclin D1 (T289). Of the 120 proteins measured, there were statistically significant difference between responders and non-responders in 61. Non-responders were characterized by increased expression and phosphorylation of Rb regulators like CDK 4 (T172), as well as expression of CDK2, Cyclin E1, and Cyclin E2. Non-responders also presented with a broad activation of the PI3K/AKT/mTOR pathway, including phosphorylated PDK1 (S241) and AKT (S473 and T308), along with the AKT substrates FoxO1 (S256), FoxO1/FoxO3 (T24/T32), mTOR (S2448), and the mTOR regulator PRAS40 (T246). Finally, the mTORC1 complex downstream substrates p70S6K (T389) and 4EBP1 (S65 and T37/46) were also increased in non-responders. Conclusion: Taken together our data suggest that expression of Rb regulators along with the activation of the PI3K/AKT/mTOR signaling axis may modulate response to ET in combination with a CDK 4/6i. Targeting these pathways may be a novel therapeutic opportunity to enhance and prolong response to this treatment.

Citation Format: Maysa Abu-Khalaf, Christos Hatzis, K. Alex Hodge, Elisa Baldelli, William Sikov, Monica Mita, Frances Valdes-Albini, Bryant Dunetz, Emanuel Petricoin, Mariaelena Pierobon. Activation of the AKT/mTOR signaling pathway is associated with response to the combination of endocrine therapy and CDK4/6 inhibitor in HR+/HER2- metastatic breast cancer [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 P2-07-05.

518 First-in-human results with the novel tumor-targeting antibody ATRC-101: phase 1b study in patients with solid tumors

Background

ATRC-101 is an engineered version of an immunoglobulin G1 antibody that was discovered in a patient with non-small cell lung cancer (NSCLC) experiencing stable disease while being treated with anti–programmed death-1 therapy. ATRC-101 targets a tumor-specific ribonucleoprotein complex containing polyadenylate binding protein-1, which has been found to be present in the majority of NSCLC, acral melanoma, breast, colorectal, and ovarian cancer samples tested. Target immunoreactivity and single-agent activity have been observed in mouse models. Preclinical data suggest that ATRC-101 stimulates both innate and adaptive immune activity against tumors.

Methods

ATRC-101-A01 is a phase 1b trial (3+3 dose escalation with expansion cohorts) in patients with solid tumors treated with ATRC-101 monotherapy every 2 or 3 weeks (Q2W or Q3W), or ATRC-101 in combination with pembrolizumab, until unacceptable toxicity or disease progression at doses of 0.3–30 mg/kg, pending dose-limiting toxicities. The primary objective is safety and secondary objectives are to characterize the pharmacokinetic profile, immunogenicity, and anti-tumor activity of ATRC-101, and to determine the recommended dose for expansion. Pharmacodynamic studies will also be performed to evaluate changes from baseline in specific immune cell populations and cytokine levels in blood and tumors. Results from the ATRC-101 0.3–30 mg/kg monotherapy Q3W cohorts are presented in this abstract (data cutoff: July 16, 2021).

Results

Twenty-four participants with solid tumors (13 colorectal, 5 ovarian, 3 breast, 2 NSCLC, 1 acral melanoma) aged 27–75 years with a median 5 lines of prior therapy were treated Q3W in five dose cohorts. No dose-limiting toxicities were observed. Eight participants (33%) experienced grade ≥3 treatment-emergent adverse events. The maximum serum concentration of ATRC-101 and treatment exposure appeared to be dose proportional. Stable disease was observed in eight patients and best response per RECIST v1.1 was associated with expression of the ATRC-101 target. Multiple biomarkers, such as treatment-associated changes in the composition of CD3+, CD4+, and CD8+ T cells in the blood, and serum cytokines/chemokines, including those predicted to activate antigen-presentation pathways, support the proposed mechanism of action of ATRC-101 and will be presented.

Conclusions

These first-in-human data suggest a manageable safety profile for ATRC-101 Q3W, with no dose-limiting toxicities observed. Pharmacokinetics appear to be dose proportional. Enrollment in the Q2W monotherapy dose-escalation cohort and at the 30 mg/kg dose level Q3W is continuing. Trial sites have been activated to test ATRC-101 in combination with pembrolizumab, and combination with chemotherapy is also planned.

Trial Registration

Trial Registration:

NCT04244552

Ethics Approval

This study was approved by the institutional review board or ethics committee as required for each participating site.

Abstract P4-01-07: A comprehensive liquid biopsy in patients undergoing neoadjuvant therapy

Background: Precision medicine is revolutionizing breast cancer (BC) care. Comprehensive liquid biopsies are a tool for personalized care in patients with locally advanced breast cancer (LABC). Identifying robust biomarkers as part of a comprehensive liquid biopsy to predict response to treatment is of immense clinical interest.

Methods: After obtaining IRB approval, serial blood samples were collected from patients with LABC undergoing neoadjuvant therapy. Paired biopsies were collected prior to treatment and were sent to Foundation Medicine for next-generation sequencing (NGS). We used a sized-base microfilter technology to capture circulating tumor cells (CTCs) and circulating cancer associated fibroblasts (cCAFs). Patients with one or more CTCs or cCAFs were deemed positive for these tests. Additionally, in collaboration with Foundation Medicine, we extracted circulating tumor DNA (ctDNA) and we analyzed it using the FoundationACT platform. Patients with a detectable genomic alteration in their plasma were considered as having a positive ctDNA test. Our primary objective is to determine if a comprehensive liquid biopsy can serve as a prognostic marker of pathologic complete response (pCR).

Results: For this analysis we describe our findings in the initial blood draw of the first 18 patients enrolled. The mean age is 54 years (38-70). All patients who had their tumors sequenced had a detectable mutation. Consistent with the findings of others, we found TP53 mutations to be the most prevalent at 83.3%. We found that 44% of patients had ctDNA, 68.4% had cCAFs and 78.9% had CTCs. Many patients also had clusters of cells, consisting of one cell type, or co-clusters, consisting of both. 38.9% had CTC clusters, 16.7% had cCAF clusters and 16.7% had co-clusters (CTCs and cCAFs together). Some patients with CTCs did not have cCAFs and vice versa. The number of CTCs and cCAFS did not correlate with stage of disease or receptor status.

Conclusions: We describe a comprehensive liquid biopsy combining a sized-based microfilter technology for CTC and cCAFs identification and the FoundationACT platform for ctDNA analysis is feasible and these biomarkers can be detected in patients with LABC prior to the initiation of neoadjuvant therapy. Our study is accruing rapidly, and we will update our results with the longitudinal collection and the prognostic value of a comprehensive liquid biopsy at the time of the meeting.

Citation Format: Sandoval Leon AC, Medina Saenz K, Miller P, Benson A, Calfa C, Mahtani R, Slingerland J, Perez A, Vogel C, Valdes-Albini F, El-Ashry D, Lippman M. A comprehensive liquid biopsy in patients undergoing neoadjuvant therapy [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 P4-01-07.

Nelfinavir induces liposarcoma apoptosis and cell cycle arrest by upregulating sterol regulatory element binding protein-1

"HIV protease-induced lipodystrophy syndrome" is associated with the use of HIV protease inhibitors for treatment of HIV infection. In-vitro studies suggest that alteration of sterol regulatory element binding protein-1 levels underlie its pathogenesis. We postulated that HIV protease inhibitors may represent a novel class of antiliposarcoma agents. SW872, FU-DDLS-1 and LiSa-2 liposarcoma, and HT1080 and 293 nonliposarcoma cell lines were treated with HIV protease inhibitors (nelfinavir, ritonavir, saquinavir, indinavir and amprenavir), and clonogenic assays were performed. Nelfinavir exhibited the most potent inhibition of clonogenicity, and further assays for proliferation, cell cycle and apoptosis were performed with nelfinavir. Immunoblots were performed for sterol regulatory element binding protein-1, proapoptotic and cell cycle-related protein expression after nelfinavir treatment. Finally, a sterol regulatory element binding protein-1-inducible SW872 cell line was developed to examine the phenotype resulting from upregulated sterol regulatory element binding protein-1. Nelfinavir selectively inhibited clonogenicity and proliferation, and induced G1 cell cycle block and induced apoptosis in a dose-dependent manner in SW872 and LiSa-2 cells, whereas it had minimal or no effect on these parameters in FU-DDLS-1 or nonliposarcoma cells. Nelfinavir induced significant sterol regulatory element binding protein-1 expression in a dose-dependent and time-dependent fashion in sensitive SW872 and LiSa-2 cells, modestly in HT1080 cells, but not in nelfinavir-insensitive FU-DDLS-1 and 293 cells without inducing adipocytic differentiation. Forced expression of sterol regulatory element binding protein-1 in inducible-SW872 cells led to the induction of proapoptotic and antiproliferative proteins, and consequent reduction of cellular proliferation. Our data indicate that nelfinavir represents a novel class of antiliposarcoma agent that acts by selectively upregulating sterol regulatory element binding protein-1 expression in liposarcomas.

Phase I trial of bortezomib in combination with topotecan in advanced solid tumor malignancies

12004

Background: Bortezomib (B) and topotecan (T) have been shown in pre-clinical testing to be synergistic. Based on this data we have performed a phase I study to determine the maximally tolerated dose and toxicities (tox) of B and T delivered sequentially. Methods: 24 pts (KPS<ECOG 3) with advanced malignancies were treated with T (2.0, 2.5, 3.0 or 3.5 mg/m2 in sequential cohorts) IV on days 1 and 8 of each three week cycle. B 1.3 mg/m2 iv was administered six hours following T on days 1 and 8, and alone on days 4 and 12. Pts were treated in cohorts of 3, the MTD dose was expanded to include 10 additional pts for PK analysis. There was no limit on prior therapies. DLT was defined as any gr 3 or 4 non-hematologic toxicity not reversible in 48h or any gr 3 thrombocytopenia lasting >7 days or associated with bleeding or any gr 4. Results: Tumor types included: breast (4), ovary (5), lung (3), others (12). 24 pts were entered (11M 13F). The median age was 55 (range: 34–83). DLT was thrombocytopenia, observed in two pts at 3.5 mg/m2 and one pt at 3.0 mg/m2 (MTD). Other grade 3 or 4 tox included fatigue, lymphopenia, hypomagnesemia, and hypertriglyceridemia. Of the 24 enrolled pts, stable disease was observed in 4 (4 or 5 cycles), 9 progressed, 5 were inevaluable and 6 are too early. PK analysis is pending. Conclusions: T and B delivered sequentially are well tolerated on a weekly schedule. DLT is thrombocytopenia. PK will be presented.(Supported by NCI Grant CA33572).

[Table: see text]

HIV protease inhibitor (PI) therapy for liposarcoma

9564

Background: Liposarcomas are the second most common soft-tissue sarcoma. Highly-active anti-retroviral therapy (HAART) with HIV PIs results in “HIV-1 protease inhibitor associated lipodystrophy syndrome,” characterized by peripheral fat wasting, central fat accumulation, insulin resistance, and hyperlipidemia. Based upon this syndrome, we hypothesized that HIV PIs might represent a novel liposarcoma therapy. Methods: SW872, LiSa-2, and FU-DDLS-1 liposarcoma, and control 293 embryonic kidney and HT1080 fibrosarcoma cell lines were treated with HIV PIs and subjected to cellular and molecular assays. Results: Clonogenic assays with SW872 cells using HIV PIs (saquinavir, ritonavir, indinavir, nelfinavir, and amprenavir) were performed. Nelfinavir demonstrated the most potent clonogenic inhibition without affecting 293 and HT1080 clonogenicity, and was studied further. Nelfinavir inhibited SW872 and LiSa-2 proliferation dose-dependently, and HT1080 proliferation at the highest concentration, without affecting FU-DDLS-1 nor 293 proliferation. Nelfinavir induced a G1 cell cycle arrest in SW872 and HT1080, but not in 293 cells. It also induced dose-dependent apoptosis in SW872, but not in 293 nor HT1080 cells. Western analyses for sterol regulatory element binding protein-1 (SREBP-1) expression, a key transcriptional regulator of fatty acid and cholesterol synthesis, were performed. Nelfinavir induced expression of SREBP-1 in nelfinavir-sensitive SW872 and LiSa-2 cells, and modestly in HT1080 cells, but not in insensitive FU-DDLS-1 nor 293 cells. Additionally, nelfinavir reduced protein expression of proliferating cell nuclear antigen (PCNA) in sensitive SW872 and LiSa-2 cells, and induced expression of the anti-proliferative protein, p21, as well as pro-apoptotic proteins, Bax and Fas, in a dose-dependent manner. Finally, forced expression of SREBP-1 with a Tet-On inducible SW872 cell line, in the absence of nelfinavir, induced expression of p21, Bax, Fas, reduced expression of PCNA, and inhibited cell proliferation. Conclusions: These studies demonstrate that nelfinavir inhibits cellular proliferation, and induces apoptosis in sensitive-liposarcoma cells through upregulation of SREBP-1. These studies validate nelfinavir as a potential, novel targeted therapy for liposarcoma.

No significant financial relationships to disclose.