Predictors of persistence of post-chemotherapy symptoms among survivors of solid tumor cancers

CONTEXT

Late or residual symptoms diminish quality of life for many cancer survivors after completion of treatment.

OBJECTIVES

Examine risk factors associated with persisting symptom burden after chemotherapy and the lack of symptom improvement over time.

METHODS

Survivors who completed curative-intent chemotherapy within two years for solid tumors were enrolled into a symptom management trial. There were 375 survivors with two or more comorbid conditions or one comorbid condition and elevated depressive symptoms (pre-defined risk factors in the trial design) who received interventions and 71 survivors without these risk factors who did not receive interventions. For all survivors, symptoms were assessed at intake, 4, and 13 weeks and categorized as mild, moderate, or severe based on the interference with daily life. The probabilities of moderate or severe symptoms and symptom improvement were analyzed using generalized mixed-effects models in relation to comorbidity, depressive symptoms, age, sex, race/ethnicity, employment, time since chemotherapy completion, and physical function. Multiple symptoms were treated as nested within the survivor.

RESULTS

Moderate or severe symptoms at baseline and the lack of improvement over time were associated with younger age and lower physical function over and above a greater number of comorbidities and elevated severity of depressive symptoms.

CONCLUSION

Risk factors identified in this research (younger age, lower physical function, greater comorbidity, and higher depressive symptoms) can be used to allocate resources for post-treatment symptom management for cancer survivors in order to relieve symptoms that do not necessarily resolve with time.

Safety and Efficacy of Tucatinib, Letrozole, and Palbociclib in Patients with Previously Treated HR+/HER2+ Breast Cancer

PURPOSE

To overcome resistance to antihormonal and HER2-targeted agents mediated by cyclin D1-CDK4/6 complex, we proposed an oral combination of the HER2 inhibitor tucatinib, aromatase inhibitor letrozole, and CDK4/6 inhibitor palbociclib (TLP combination) for treatment of HR+/HER2+ metastatic breast cancer (MBC).

PATIENTS AND METHODS

Phase Ib/II TLP trial (NCT03054363) enrolled patients with HR+/HER2+ MBC treated with ≥2 HER2-targeted agents. The phase Ib primary endpoint was safety of the regimen evaluated by NCI CTCAE version 4.3. The phase II primary endpoint was efficacy by median progression-free survival (mPFS).

RESULTS

Forty-two women ages 22 to 81 years were enrolled. Patients received a median of two lines of therapy in the metastatic setting, 71.4% had visceral disease, 35.7% had CNS disease. The most common treatment-emergent adverse events (AE) of grade ≥3 were neutropenia (64.3%), leukopenia (23.8%), diarrhea (19.0%), and fatigue (14.3%). Tucatinib increased AUC10-19 hours of palbociclib 1.7-fold, requiring palbociclib dose reduction from 125 to 75 mg daily. In 40 response-evaluable patients, mPFS was 8.4 months, with similar mPFS in non-CNS and CNS cohorts (10.0 months vs. 8.2 months; P = 0.9). Overall response rate was 44.5%, median duration of response was 13.9 months, and clinical benefit rate was 70.4%; 60% of patients were on treatment for ≥6 months, 25% for ≥1 year, and 10% for ≥2 years. In the CNS cohort, 26.6% of patients remained on study for ≥1 year.

CONCLUSIONS

TLP combination was safe and tolerable. AEs were expected and manageable with supportive therapy and dose reductions. TLP showed excellent efficacy for an all-oral chemotherapy-free regimen warranting further testing. See related commentary by Huppert and Rugo, p. 4993.

Safety and Tolerability of a Novel Anti-HER2 Antibody-Drug Conjugate (PF-06804103) in Patients with HER2-Expressing Solid Tumors: A Phase 1 Dose-Escalation Study

PF-06804103 is an anti-HER2 antibody-drug conjugate with auristatin payload. We evaluated its safety, tolerability, and antitumor activity in patients with advanced/unresectable or metastatic breast and gastric cancers. This multicenter, open-label, first-in-human, phase 1 study (NCT03284723) comprised dose escalation (P1) and dose expansion (P2). In P1, adults with HER2+ breast or gastric cancer received PF-06804103 0.15-5.0 mg/kg intravenously once/21 days (Q3W); in P2, patients with HER2+ or HER2-low (IHC 1+ or IHC 2+/ISH-) breast cancer received 3.0 or 4.0 mg/kg Q3W. The primary endpoints were dose-limiting toxicities (DLT) and safety (P1), and objective response rate (ORR) assessed using RECIST v1.1 (P2). Ninety-three patients enrolled in P1 (n = 47: HER2+ gastric cancer = 22, HER2+ breast cancer = 25) and P2 [n = 46: HER2+ breast cancer = 19, hormone receptor (HR)+ HER2-low breast cancer = 27] received PF-06804103. Four patients (3.0- and 4.0-mg/kg groups, n = 2 each) had DLTs (mostly Grade 3). Safety and efficacy results showed a dose-response relationship. Adverse events (AE) leading to treatment discontinuation (44/93, 47.3%) included neuropathy (11/93, 11.8%), skin toxicity (9/93, 9.7%), myalgia (5/93, 5.4%), keratitis (3/93, 3.2%), and arthralgia (2/93, 2.2%). Two (2/79, 2.5%) patients (P1, 4.0- and 5.0-mg/kg groups, n = 1 each) achieved complete response; 21 (21/79, 26.6%) achieved partial response. In P2, ORR was higher in HER2+ compared with HR+ HER2-low breast cancer [3.0 mg/kg: 16.7% (2/12) vs. 10.0% (1/10); 4.0 mg/kg: 47.4% (9/19) vs. 27.3% (3/11)]. PF-06804103 demonstrated antitumor activity; however, AEs led to discontinuation in 47.3% of patients. Safety and efficacy were dose-dependent.

Transcranial Magnetic Stimulation for the Treatment of Chemo Brain

This pilot feasibility study aimed to evaluate the effects of transcranial magnetic stimulation (TMS) on chemotherapy-related cognitive impairment (CRCI), and we report here on the first patient.

BACKGROUND

Deleterious cognitive changes due to chemotherapy or CRCI are commonly referred to as "chemo brain". With the increasing survival of cancer patients, this poorly understood and inadequately treated condition will likewise have an increasing toll on individuals and society. Since there is no approved treatment for chemo brain, we have initiated a therapeutic trial using transcranial magnetic stimulation (TMS), a non-invasive brain stimulation technique approved in many countries for the treatment of neurologic and psychiatric conditions like migraine and depression.

CASE PRESENTATION

A 58-year-old woman, diagnosed 7 years prior with left breast cancer, underwent partial mastectomy with sentinel lymph node biopsy. She then received four cycles of adjuvant chemotherapy followed by radiation therapy. Afterwards, she was on tamoxifen for 4 years and then switched to aromatase inhibitors. The patient's CRCI started during chemotherapy and severely impaired her quality of life for an additional two years. In the third year after chemotherapy, the CRCI partially cleared to stabilize to the level at the time of presentation for this trial. The patient continues to have memory difficulties and decreased concentration, which makes multi-tasking very difficult to impossible. She is reliant on memory aids at work and at home. The participant underwent 10 consecutive sessions of TMS during weekdays for 2 weeks. Stimulation was directed to the left dorsolateral prefrontal cortex. After TMS, the participant significantly improved in memory function on neuropsychological testing. While she reported no subjective differences in concentration or memory, she did report an improvement in her sleep. Functional magnetic resonance imaging of the brain before and after TMS showed increased resting-state functional connectivity between the stimulation site and several brain regions. Remarkably, after 6 years of chemo brain and remaining in the same position at work due to her inability to concentrate and multi-task, she applied for and received a promotion 5-6 months after her TMS treatments.

CONCLUSIONS

This first patient in the phase 1 clinical trial testing of TMS for the treatment of "chemo brain" provided important lessons for feasibility and insights into mechanisms of potential benefit.

Nuclear epidermal growth factor receptor as a therapeutic target

Epidermal growth factor receptor (EGFR) is one of the most well-studied oncogenes with roles in proliferation, growth, metastasis, and therapeutic resistance. This intense study has led to the development of a range of targeted therapeutics including small-molecule tyrosine kinase inhibitors (TKIs), monoclonal antibodies, and nanobodies. These drugs are excellent at blocking the activation and kinase function of wild-type EGFR (wtEGFR) and several common EGFR mutants. These drugs have significantly improved outcomes for patients with cancers including head and neck, glioblastoma, colorectal, and non-small cell lung cancer (NSCLC). However, therapeutic resistance is often seen, resulting from acquired mutations or activation of compensatory signaling pathways. Additionally, these therapies are ineffective in tumors where EGFR is found predominantly in the nucleus, as can be found in triple negative breast cancer (TNBC). In TNBC, EGFR is subjected to alternative trafficking which drives the nuclear localization of the receptor. In the nucleus, EGFR interacts with several proteins to activate transcription, DNA repair, migration, and chemoresistance. Nuclear EGFR (nEGFR) correlates with metastatic disease and worse patient prognosis yet targeting its nuclear localization has proved difficult. This review provides an overview of current EGFR-targeted therapies and novel peptide-based therapies that block nEGFR, as well as their clinical applications and potential for use in oncology.

Dose escalation and expansion cohorts in patients with advanced breast cancer in a Phase I study of the CDK7-inhibitor samuraciclib

Samuraciclib is a selective oral CDK7-inhibitor. A multi-modular, open-label Phase I study to evaluate safety and tolerability of samuraciclib in patients with advanced malignancies was designed (ClinicalTrials.gov: NCT03363893). Here we report results from dose escalation and 2 expansion cohorts: Module 1A dose escalation with paired biopsy cohort in advanced solid tumor patients, Module 1B-1 triple negative breast cancer (TNBC) monotherapy expansion, and Module 2A fulvestrant combination in HR+/HER2- breast cancer patients post-CDK4/6-inhibitor. Core study primary endpoints are safety and tolerability, and secondary endpoints are pharmacokinetics (PK), pharmacodynamic (PD) activity, and anti-tumor activity. Common adverse events are low grade nausea, vomiting, and diarrhea. Maximum tolerated dose is 360 mg once daily. PK demonstrates dose proportionality (120 mg-480 mg), a half-life of approximately 75 hours, and no fulvestrant interaction. In dose escalation, one partial response (PR) is identified with disease control rate of 53% (19/36) and reduction of phosphorylated RNA polymerase II, a substrate of CDK7, in circulating lymphocytes and tumor tissue. In TNBC expansion, one PR (duration 337 days) and clinical benefit rate at 24 weeks (CBR) of 20.0% (4/20) is achieved. In combination with fulvestrant, 3 patients achieve PR with CBR 36.0% (9/25); in patients without detectable TP53-mutation CBR is 47.4% (9/19). In this study, samuraciclib exhibits tolerable safety and PK is supportive of once-daily oral administration. Clinical activity in TNBC and HR+/HER2-breast cancer post-CDK4/6-inhibitor settings warrants further evaluation.

A Sequential Multiple Assignment Randomized Trial of Symptom Management After Chemotherapy

CONTEXT

Many cancer survivors experience a lingering symptom burden after chemotherapy.

OBJECTIVES

In this sequential multiple assignment randomized trial, we tested optimal sequencing of two evidence-based interventions for symptom management.

METHODS

Survivors of solid tumors (N = 451) were interviewed at baseline and stratified as high or low need for symptom management based on comorbidity and depressive symptoms. High need survivors were randomized initially to the 12-week Symptom Management and Survivorship Handbook (SMSH, N = 282) or 12-week SMSH with eight weeks of Telephone Interpersonal Counseling (TIPC, N = 93) added during weeks one to eight. After four weeks of the SMSH alone, non-responders on depression were re-randomized to continue with SMSH alone (N = 30) or add TIPC (N = 31). Severity of depression and summed severity index of 17 other symptoms over weeks one to13 were compared between randomized groups and among three dynamic treatment regimes (DTRs): 1) SMSH for 12 weeks; 2) SMSH for 12 weeks with eight weeks of TIPC from week one; 3) SMSH for four weeks followed by SMSH+TIPC for eight weeks if no response to the SMSH alone on depression at week four.

RESULTS

There were no main effects for randomized arms or DTRs, but there was a significant interaction of trial arm with baseline depression favoring SMSH alone during weeks one to four in the first randomization and SMSH+TIPC in the second randomization.

CONCLUSION

The SMSH may represent a simple effective option for symptom management, adding TIPC only when there is no response to SMSH alone for people with elevated depression and multiple co-morbidities.

Oxylipins as Biomarkers for Aromatase Inhibitor-Induced Arthralgia (AIA) in Breast Cancer Patients

Aromatase inhibitor-induced arthralgia (AIA) presents a major problem for patients with breast cancer but is poorly understood. This prospective study explored the inflammatory metabolomic changes in the development of AIA. This single-arm, prospective clinical trial enrolled 28 postmenopausal women with early-stage (0-3) ER+ breast cancer starting adjuvant anastrozole. Patients completed the Breast Cancer Prevention Trial (BCPT) Symptom Checklist and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) at 0, 3, and 6 months. The plasma levels of four polyunsaturated fatty acids (PUFAs) and 48 oxylipins were quantified at each timepoint. The subscores for WOMAC-pain and stiffness as well as BCPT-total, hot flash, and musculoskeletal pain significantly increased from baseline to 6 months (all p < 0.05). PUFA and oxylipin levels were stable over time. The baseline levels of 8-HETE were positively associated with worsening BCPT-total, BCPT-hot flash, BCPT-musculoskeletal pain, WOMAC-pain, and WOMAC- stiffness at 6 months (all p < 0.05). Both 9-HOTrE and 13(S)-HOTrE were related to worsening hot flash, and 5-HETE was related to worsening stiffness (all p < 0.05). This is the first study to prospectively characterize oxylipin and PUFA levels in patients with breast cancer starting adjuvant anastrozole. The oxylipin 8-HETE should be investigated further as a potential biomarker for AIA.

Abstract P1-05-04: Physician Practice Patterns of Breast Imaging After Treatment: Survey of Real-World Practice

Introduction: Mammography is the cornerstone of breast cancer screening, diagnosis, and surveillance. After definitive treatment for breast cancer, mammograms are continued for surveillance. The current recommendations regarding surveillance after definitive treatment (surgery and radiation) lack consensus amongst various societies. There are no clear guidelines in regards to the type of mammogram recommended: diagnostic or screening mammogram or if a diagnostic mammogram is used, when to return to routine screening protocols. Current practice patterns are driven by physician’s preference. We conducted a survey to evaluate physicians’ preferences in ordering breast imaging post- breast cancer diagnosis and treatment. Methods: This survey was approved by University of Arizona institutional review board. This survey was conducted through American Society of Clinical Oncology (ASCO) voluntary opt-in Research Survey Pool (RSP). ASCO sent out this survey to 1000 randomly selected members between 10/19/2021-11/22/2021. Weekly reminders to participate were sent through the ASCO RSP for 5 weeks. Participants clicked the link to the survey platform where upon consent they completed the survey. Results: The survey was completed by 244 healthcare professionals through the ASCO RSP. Most respondents were physicians (n=228), primarily medical oncologists (n=174) and practiced in an academic environment in the United States (n=132). After definitive treatment, majority (58%) ordered first imaging at 6 months post-surgery/radiation, and it was primarily a diagnostic mammogram (68%). Interestingly, for patients at age 80 or above, screening mammogram was used for surveillance after definitive treatment by most respondents (59%). After first post-surgery/radiation mammogram there is an almost even spilt (50%) on continuing with diagnostic versus screening mammograms for follow up. Of those who order diagnostic mammograms, majority (38%) do it for 3-5 years with an additional 30% continuing it beyond 5 years. Almost 65% of respondents reported they do not stop screening mammograms at any age for patients with a history of early-stage breast cancer as long as they are healthy. Conclusions: The practice patterns of healthcare professionals as it relates to the type and frequency of breast imaging varies significantly. Despite having the same imaging quality there is a significant difference in the cost of screening and diagnostic mammograms. In addition, in clinical practice, most routine screening care is covered by insurances without co-pays or out of pocket costs for patients. Diagnostic imaging does not fall under routine screening care and frequently requires out of pocket expenses for patients. As insurance companies start to decline certain imaging modalities used for cancer detection due to lack of data supporting the use of these expensive studies, specific imaging guidelines for follow up in post-treatment setting for patients with breast cancer are needed.

Citation Format: Meredith Whittaker, Kiah Farr, Preethika Potluri, Nova Foster, Jennifer Erdrich, Jennifer Segar, Sima Ehsani, Sao Jiralerspong, Denise Roe, Pavani Chalasani. Physician Practice Patterns of Breast Imaging After Treatment: Survey of Real-World Practice [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 P1-05-04.

Abstract P4-01-16: High levels of RSK2 in breast cancer patients is associated with longer PFS in patients treated with PMD-026, a first in class RSK inhibitor

Background: Breast cancer (BC) is the most common malignancy in women and metastatic triple negative breast cancer (mTNBC) remains one of the most difficult to treat cancers with few targeted treatment options. RSK is recognized as a critical signaling component in the MAPK/PDK-1 pathways, is an important driver for BC and a signature of poor prognosis. PMD-026 is the first RSK inhibitor to enter clinical trials and is being developed alongside an immunohistochemistry (IHC) companion diagnostic to select patients with increased activated RSK2 in tumor tissue. A Phase 1/1b trial of PMD-026 in patients with metastatic breast cancer (mBC) or metastatic triple negative breast cancer (mTNBC) established safety at a dose of 200 mg Q12h. Efficacy signals in patients with heavily pretreated mBC/mTNBC are explored in this analysis along with evaluation of the effect of food (FE) on systemic exposure to treatment. Methods: PMD-026 was administered to 41 patients as a single agent in this phase 1/1b open-label study, with 30 patients evaluable for efficacy. Exploratory objectives were to identify subgroups of patients who may optimally benefit from PMD-026. Subgroup analysis of patients included 1) comparing BC patients who received ≤5 vs &gt;5 prior therapies; 2) comparing TNBC patients (de novo vs secondary subtypes)1, and 3) comparing patients with low RSK2 H-scores (&lt; 180) vs high (≥180). In addition, PMD 026 PK was evaluated at the 200 mg Q12h dose and a FE sub-study enrolled 12 patients administered a single 200 mg dose. Results: PMD-026 monotherapy was generally well-tolerated in the 41 mBC patients who were enrolled and treated. Kaplan-Meier PFS analysis of 30 evaluable BC patients who were dosed with PMD-026 showed that patients with less prior therapy (≤5) did significantly better (HR, 0.19; 95% CI [0.06–0.52], p=0.0014) than those with &gt; 5 prior therapies. Subgroup analysis of PFS in those with TNBC demonstrated that de novo TNBC (n=17) had longer time on treatment with PMD-026 compared with secondary TNBC (n=9) (HR, 0.31; 95% CI [0.10-0.99], p=0.0476). In those with de novo TNBC with ≤5 prior therapies, a high RSK2 H-score was associated with significantly longer PFS at the RP2D (4.2 vs 1.3 months, HR, 0.17; 95% CI [0.03-0.80], p=0.0254) than patients with a low RSK2 H-score. In patients with CDK4/6 resistant HR+ BC (n=3), PFS was 5.2 (RSK2 high) vs 1.3 months (RSK2 low). Stable disease was observed in 53% (9/17) of patients with de novo TNBC and in 67% (6/9) of de novo TNBC patients with high RSK2. Tumor necrosis or target lesion reduction (&lt; 30%) was observed in 17% of patients (5/30), all of whom had high RSK2 expression. In the FE sub-study, increased interpatient variability in PMD-026 Cmax and Tmax but not AUC, was observed when administered with food, favored dosing in a fasted state, which is consistent with the pH dependent solubility of PMD-026. Notably, all FE patients (12/12) achieved the target concentration of 1µM (IC90 in preclinical studies) within 4 hours when PMD-026 was taken without food. At the RP2D, PMD-026 taken without food showed relatively consistent exposure among patients over 24 hr timeframe. Conclusions: These findings demonstrate that in patients treated with PMD-026 who had received &lt; 5 prior treatment regimens, had de novo TNBC or CDK4/6 refractory HR+ disease and had high RSK2 scores had longer PFS. Overall, PMD-026 is a well-tolerated, orally available RSK2 inhibitor that will be evaluated further for efficacy in TNBC and CDK4/6i refractory HR+ mBC, in a trial that will prospectively enroll patients based on RSK2 activation as defined by the RSK2 IHC H-scores. Clinical trial information: NCT04115306. 1 Patients diagnosed and treated for TNBC from their initial diagnosis (de novo TNBC) vs patients previously treated for hormone receptor positive (HR+) or human epidermal growth factor 2 receptor positive (HER2+) BC, but became HR or HER2 negative (secondary TNBC)

Citation Format: Judy S. Wang, Muralidhar Beeram, Pavani Chalasani, Lida Mina, Rebecca A. Shatsky, Sara Hurvitz, Meghna S. Trivedi, Robert Wesolowski, Hyo S. Han, Amita Patnaik, Shakeela Bahadur, My-my Huynh, Aarthi Jayanthan, Gerrit Los, Sandra E. Dunn, Andrew Dorr. High levels of RSK2 in breast cancer patients is associated with longer PFS in patients treated with PMD-026, a first in class RSK inhibitor [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 P4-01-16.

Social Determinants of Health and Symptom Burden During Cancer Treatment

BACKGROUND

Cancer survivors (defined as individuals from diagnosis to the end of life) in treatment experience multiple physical and psychological symptoms (e.g., fatigue, pain, depression, anxiety, disturbed sleep) that influence their well-being and treatment outcomes. Underrepresented cancer survivors may disproportionately experience greater symptom burden (number of symptoms, symptom severity, depression, anxiety).

OBJECTIVES

The aim of this study was to examine the relationships of social determinants of health, including age, ethnicity, education, income and whether income meets the survivor's needs, neighborhood (rural vs. urban), access to healthcare (e.g., insurance), and social isolation, with symptom burden in cancer survivors.

METHODS

This secondary analysis included baseline data from 400 cancer survivors of solid tumor cancers undergoing chemotherapy or targeted therapy who participated in a larger randomized trial of symptom management interventions. Symptom burden was measured by the Center for Epidemiological Studies-Depression scale for depression and Patient-Reported Outcomes Measurement Information System scores for anxiety and social isolation, summed severity index of 16 symptoms from the General Symptom Distress Scale, and the total number of symptoms. Self-reported comorbid conditions were measured using the Bayliss tool. General linear models were used to relate symptom measures (one at a time) to age, number of comorbid conditions, level of education, marital status, income meeting needs, and size of metropolitan neighborhood. Additional covariates included site of cancer, its treatment, and whether the cancer was metastatic.

RESULTS

Non-Hispanic White survivors ( n = 191) were older and had more comorbid conditions, a higher proportion of metastatic cancers, and higher levels of education and income compared with Hispanic survivors ( n = 168) and non-Hispanic survivors of other races ( n = 41). Compared with the other two groups, Hispanic survivors had the lowest rate of health insurance availability, and non-Hispanic survivors of other races had the lowest social isolation. Age, number of comorbid conditions, and social isolation were significantly associated with number of symptoms, symptom severity, and depression. Age and social isolation were associated with anxiety. In addition, the symptom severity of non-Hispanic White survivors was lower than that of Hispanic survivors and non-Hispanic survivors of other races.

DISCUSSION

These findings highlight the health disparities in symptom burden experienced among cancer survivors when considering their social determinants of health. Assessing these may help clinicians address health disparities in cancer care.

Abstract P4-04-02: Evaluation of Dronabinol to Decrease Opioid Use for Cancer- Induced Bone Pain

Purpose Bone metastases (BM) from breast cancer cause significant complications including pain, hypercalcemia, spinal cord compression, and pathologic fractures, collectively referred to as skeletal related events (SREs). Of all SREs, bone pain impacts the quality of life (QOL) most significantly. Cancer- induced bone pain (CIBP) is difficult to treat with limited treatment options and requires a multimodal approach. Management of CIBP is primarily by opioids which have notable side effects like sedation, constipation, and concern for addiction. In addition, pre-clinical evidence suggests that opioids accelerate bone loss and increase risk of fractures. There is an unmet need for novel analgesic therapy interventions to optimize QOL for patients with BM from metastatic breast cancer. Preclinical studies have shown that the endogenous cannabinoid (CB) system is involved in pain modulation, bone regulation, immunity, and restraint of cancer pathogenesis. CB2 receptor activation has been shown to inhibit proinflammatory cytokines/chemokines in pre-clinical models. Treatment with selective CB2 agonist in mice with BM led to significant antinociception, decreased cancer-induced bone degradation, and reduced side effects of morphine. In addition to alleviating pain, CB2 agonists were shown to enhance bone growth/strength in these mice. Based on this pre-clinical data, we hypothesized that the addition of a CB2 agonist will improve pain symptoms and decrease opioid requirement in patients with bone metastases from breast cancer. We proceeded to conduct a pilot study by repurposing a clinically approved CB2/CB1 agonist, dronabinol. Methods We conducted a prospective, single site study among patients with BM from breast cancer at our center (NCT03661892). Patients had to have been on opioids for CIBP for at least 4 weeks and not using marijuana or CBD products. Patients were treated with 10mg dronabinol BID for 8 weeks. Our primary objective was to determine the proportion who decrease their opioid use by ≥ 20%. The null hypothesis value was 5% of women would have a 20% decrease. With 14 participants, we could detect an increase from 5% to 29% (n=4) with 80% statistical power using a one-sided alpha level of 0.05. Participants completed Brief Pain Inventory and the European Organization for Research and Treatment of Cancer quality of life questionnaires pre and post treatment. Results Twenty participants consented with 14 patients completing the study and evaluable for primary analysis. No patients received any palliative radiation therapy or other therapies for bone pain within 3 months prior to enrollment to this study. Four patients decreased their opioid use by ≥ 20% meeting the primary objective. Patients reported significant improvement in pain severity, interference scores, quality of life and insomnia based on the questionnaires. There were no grade 4 side effects and only 1 patient had grade 3 adverse event (dizziness) related to study drug. Of the 14 patients who completed the study, 9 desired to continue dronabinol therapy after completion. Conclusion Our pilot study shows that the addition of dronabinol resulted in decreased opioid requirements for CIBP in patients with metastatic breast cancer. Patient-reported outcomes also demonstrated improved pain and QOL with the addition of dronabinol. While we did not see any significant AEs tolerability may be of concern due to CB1 psychoactive effects. Our results are promising and warrant further investigation into evaluating CB2 agonists for improved pain control from CIBP and to decrease opioid use.

Citation Format: Jennifer Segar, Kiah Farr, Mary Junak, Denise Roe, Sima Ehsani, Sao Jiralerspong, Ibrahim Mohab, Todd Vanderah, Pavani Chalasani. Evaluation of Dronabinol to Decrease Opioid Use for Cancer- Induced Bone Pain [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 P4-04-02.

Abstract P065: Effects of metformin on breast tissue inflammation in premenopausal women with components of metabolic syndrome

Background: Obesity, with increasing worldwide prevalence, is associated with increased breast cancer burden. The association is attributed to multiple metabolic disturbances including chronic inflammation due to dysfunctional adipose tissue. Features of local breast adipose tissue inflammation such as macrophage infiltration and an enriched pro-inflammatory gene signature were recently reported in mouse models of obesity and in women with high adiposity or metabolic disorders. Strategies that can reduce obesity-induced chronic inflammation may lead to reduction of breast cancer risk. Metformin, a widely used anti-diabetic drug, exerts favorable effects on multiple metabolic disturbances. This study aims to evaluate the clinical effects of metformin on breast tissue inflammation. Methods: Macrophage infiltration and polarization were determined in breast core needle biopsies collected at baseline and 6 months after agent intervention from a Phase II randomized, double-blind, placebo-controlled trial of metformin in premenopausal women with components of metabolic syndrome. Macrophage infiltration was assessed using a pan macrophage marker (CD68) by immunohistochemistry (IHC). M1 and M2 macrophages were assessed using CD40 and CD206 surface markers, respectively, by IHC. The primary endpoint is the change in macrophage density in breast adipose tissue. Secondary endpoints include the change in macrophage density in breast stroma and epithelium tissues, the proportion of M1 (pro-inflammatory) and M2 (anti-inflammatory) macrophages in breast adipose, stroma, and epithelium tissues. Results: Baseline biopsies from 76 participants (40 in the metformin arm and 36 in the placebo arm) were available for CD68 analysis. The baseline CD68 density was 22.48 ± 3.25, 67.26 ± 9.68, 418.81± 71.02 (mean±SE) per mm2 in breast adipose, stroma, and epithelium tissues, respectively. Biopsies from 71 participants (34 in the metformin arm and 37 in the placebo arm) were available for CD68 analysis at 6 months. Comparing to placebo, metformin intervention led to a significant reduction in CD68 density in breast adipose tissue (p = 0.01) but did not change the CD68 density in breast epithelium and stroma tissues. Conclusion: Metformin intervention resulted in favorable changes in macrophage infiltration in breast adipose tissue in premenopausal women with component of metabolic syndrome. Studies are ongoing to evaluate the effects of metformin on macrophage polarization.

Citation Format: Liane E. Pinto, Sara Centuori, Jose Guillen-Rodriguez, Denise J. Roe, Edgar Tapia, Pavani Chalasani, H-H. Sherry Chow. Effects of metformin on breast tissue inflammation in premenopausal women with components of metabolic syndrome. [abstract]. In: Proceedings of the AACR Special Conference: Precision Prevention, Early Detection, and Interception of Cancer; 2022 Nov 17-19; Austin, TX. Philadelphia (PA): AACR; Can Prev Res 2023;16(1 Suppl): Abstract nr P065.

Camptothesome Potentiates PD-L1 Immune Checkpoint Blockade for Improved Metastatic Triple-Negative Breast Cancer Immunochemotherapy

In this study, we focus on investigating the therapeutic effects of camptothesome on treating metastatic triple-negative breast cancer (TNBC). We elucidate that camptothesome elicited stronger immunogenic cell death (ICD) compared to free camptothecin (CPT) and Onivyde in 4T1 TNBC cells. In addition, camptothesome is mainly internalized by the 4T1 and MDA-MB-231 cells through clathrin-mediated endocytosis based on the results of flow cytometry. Through real-time Lago optical imaging, camptothesome shows excellent tumor-targeting efficiency in orthotopic TNBC tumors. We demonstrate that camptothesome can upregulate programmed death-ligand 1 (PD-L1) in 4T1 tumors in an interferon gamma (IFN-γ)-dependent manner. Furthermore, the anti-TNBC efficacy studies reveal that camptothesome is superior to Onivyde and markedly potentiates PD-L1 immune checkpoint blockade therapy with complete lung metastasis remission in an orthotopic 4T1-Luc2 tumor model. This combination therapy eliciting robust cytotoxic T lymphocytes (CTL) response via boosting tumor-infiltrating cluster of differentiation 8 (CD8), calreticulin (CRT), high mobility group box 1 protein (HMGB-1), low-density lipoprotein receptor-related protein 1 (LRP1), IFN-γ, and granzyme B. Our work corroborates the promise of camptothesome in favorably modulating tumor immune microenvironment via inducing ICD to fortify the PD-L1 checkpoint blockade therapy for improved treatment of intractable TNBC.

Investigating keratinocyte growth factor hair serum for the prevention of chemotherapy-induced alopecia

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Background: Chemotherapy induced alopecia (CIA) is known to have a significant psychological and quality of life impact, mainly in women. While cold caps have been shown to decrease CIA, expense, availability, and extension of treatment durations are barriers for routine clinical use. Keratinocyte Growth Factor (KGF) has been shown to have cytoprotective effects on human keratinocytes in vitro and reduce apoptosis in human hair follicles. Based on this data, we hypothesized that KGF-Hair serum (KGF-HS) will prevent CIA in women undergoing chemotherapy as treatment for breast cancer. Methods: We designed a Simon 2-stage prospective study to test our hypothesis. Study was approved by our institutional review board and registered on clinicaltrials.gov (NCT04554732). In part 1 we planned to enroll 20 patients into a single arm. If ≥ 4 responses are noted, we proposed to initiate part 2: randomized double-blind placebo-controlled study. Patients with early-stage breast cancer (ESBC) who were scheduled to get at least 4 cycles of anthracycline or taxane based chemotherapy were included. Patients with inflammatory scalp conditions, hair loss disorder, scalp disorders were excluded. The primary endpoint was successful hair preservation using the Common Terminology Criteria for Adverse Events 4.0 scale at the end of 4 cycles of chemotherapy. Secondary end points included wig use and scores on the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire–Core 30, Hospital Anxiety and Depression Scale, and a summary scale of the Body Image Scale. Results: Twenty patients completed part 1 of the study and were evaluable for primary endpoint. Mean age was 60 years and 70% were treated with taxane based chemotherapy. Successful hair preservation was noted in 0 of 20 women. Mean duration of treatment with KGF-HS was 4.6wks (range 2-10 weeks) before women came off study due to grade 2 hair loss. There were no statistically significant differences in changes in any of the scales of quality of life from baseline to end of treatment. There were only 2 grade 1 events (1 rash and 1 itching) reported which resolved after coming off the KGF-HS. There were no serious adverse device events. Conclusions: Among women with early-stage breast cancer receiving chemotherapy with a taxane, anthracycline, or both, using KGF-HS did not prevent CIA. Further research is needed to investigated other novel topical options to prevent CIA. Clinical trial information: NCT04554732.

Use of scheduled and unscheduled health services by cancer survivors and their caregivers

PURPOSE

The purpose was to determine predictors of scheduled and unscheduled health services use by cancer survivors undergoing treatment and their informal caregivers.

METHODS

English- or Spanish-speaking adult cancer survivors undergoing chemotherapy or targeted therapy for a solid tumor cancer identified a caregiver (N = 380 dyads). Health services use over 2 months was self-reported by survivors and caregivers. Logistic regression models were used to relate the likelihood of service use (hospitalizations, emergency department [ED] or urgent care visits, primary care, specialty care) to social determinants of health (age, sex, ethnicity, level of education, availability of health insurance), and number of comorbid conditions. Co-habitation with the other member of the dyad and other member's health services use were considered as additional explanatory variables.

RESULTS

Number of comorbid conditions was predictive of the likelihood of scheduled health services use, both primary care and specialty care among caregivers, and primary care among survivors. Greater probability of specialty care use was associated with a higher level of education among survivors. Younger age and availability of health insurance were associated with greater unscheduled health services use (hospitalizations among survivors and urgent care or ED visits among caregivers). Unscheduled health services use of one member of the dyad was predictive of use by the other.

CONCLUSIONS

These findings inform efforts to optimize health care use by encouraging greater use of scheduled and less use of unscheduled health services. These educational efforts need to be directed especially at younger survivors and caregivers.

Real-world data on outcomes using taxane, trastuzumab, and pertuzumab (THP) in patients with early stage HER2+ breast cancer

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Background: In HER2+ early breast cancer, dual HER2 targeted combination of trastuzumab and pertuzumab with chemotherapy achieved higher rates of pathologic complete response (pCR) and improved long term outcomes. However, the optimal chemotherapy backbone is still under investigation. While neoadjuvant taxane in combination with trastuzumab and pertuzumab (THP) has been investigated in NEOSPHERE, patients received anthracycline-based regimen in the adjuvant setting. We report real-world data on long-term patient outcomes after neoadjuvant THP. Methods: An IRB-approved retrospective chart review at 2 academic centers was conducted using EMR to identify women with stage I-III HER2+ breast cancer who exclusively received neoadjuvant THP between 2013-2020. Clinicopathological characteristics and follow up information were extracted from surgical pathology and medical records. Results: 71 patients met criteria (median, 55 years). At presentation, 56 (79%) patients had stage II - III disease and 45 (63%) were lymph node negative. The majority of tumors were ER+ (43 patients, 61%) and received paclitaxel (46 patients, 65%) as their taxane backbone. pCR was achieved in 40 (56%) patients (Table); 38 (95%) continued with adjuvant HER2 therapy alone; 1 received adjuvant endocrine therapy only and 1 received no further treatment. Of the 31 (44%) patients without pCR, 9 received additional adjuvant chemotherapy in addition to HER2 directed therapy while 18 continued with HER2 therapy alone. During the follow-up period (median 34.7 mo, range 6.8-98.9 mo), 3 patients with lymph node positive disease on presentation had disease relapse. Two of the patients with pCR had local recurrence and one without pCR had distant metastasis (brain, lung). The 2 patients with local recurrence were successfully treated with salvage therapy and remain in remission. The patient with metastatic disease remains alive and on treatment. Conclusions: We showed that a real world HER2+ patient population treated with neoadjuvant THP achieved pCR rates consistent with what has been previously reported. In addition, with a median follow up of ̃ 3 years, only 3 patients had relapse supporting the utility of THP as potential de-escalation treatment in the neoadjuvant setting. Ongoing prospective trials, like NCT03716180, will further confirm the efficacy of this regimen in a prospective setting.[Table: see text]

Abstract P1-10-02: Effect of metformin on metabolic markers associated with breast cancer risk in a phase II clinical trial in overweight/obese premenopausal women

Background: The increasing rate of obesity in the United States is accompanied by serious health concerns. Obesity increases breast cancer burden and is associated with increased risk of triple-negative breast cancer in premenopausal women and overall poor prognosis in breast cancer patients. There is a need for intervention strategies aiming to reduce obesity-associated dysregulation to attenuate breast cancer risk.Methods: We conducted a Phase II, double-blind, randomized, placebo-controlled clinical trial in overweight/obese premenopausal women with elements of metabolic syndrome to assess the potential of metformin to reduce obesity-associated breast cancer risk. Study participants received metformin (850 mg BID, n = 76) or placebo (n = 75) for 12 months. Fasting blood samples were collected at baseline, 6-months and 12-months from each participant. We analyzed the effects of metformin on circulating levels of insulin/IGF axis, adipokines, and neutrophil-to-lymphocyte ratio in samples collected from this trial. Serum concentrations of insulin, IGF-1, IGFBP-3, leptin and high-molecular weight adiponectin were measured using ELISA immunoassays. Results: The study population included 151 women and had a mean age of 39.5 years, mean body mass index (BMI) was 37.8 and study participants had a large waist and at least one other component of metabolic syndrome. Metformin treatment did not result in significant changes in members of the insulin/IGF axis compared to the placebo group, however, limiting the analysis to participants with detectable metformin in the blood serum resulted in favorable changes in insulin (p=0.0215), HOMA-IR (p&lt;0.001) and a significant increase in IGFBP-3 (p=0.0176) in the metformin group after the intervention. We observed significant decreases in leptin (p=0.0018) and the leptin-to-adiponectin ratio (p=0.0036) in the metformin arm longitudinally. Additionally, we observed a significant reduction in the neutrophil-to-lymphocyte ratio (NLR), a systemic inflammation marker, in the metformin group compared to the placebo group (p=0.0170). Conclusions: We conclude that metformin led to favorable changes in metabolic markers associated with breast cancer risk in the metformin treated participants, however, the changes were not significantly different from the placebo group. The NLR was significantly reduced after metformin intervention compared to the placebo group. More research is needed to understand the effects of metformin on the insulin/IGF axis and adipokines in overweight/obese premenopausal women.

Citation Format: Edgar Tapia, Diana Villa-Guilen, Pavani Chalasani, Sara Centuori, Denise J. Roe, Jose Guillen, Catherine Cordova, Liane Pinto, Sherry Chow. Effect of metformin on metabolic markers associated with breast cancer risk in a phase II clinical trial in overweight/obese premenopausal women [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-10-02.

Abstract P1-17-02: ZN-c5, an oral selective estrogen receptor degrader (SERD), in women with advanced estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer

Background: Hormone receptor+/HER2- breast cancer is the most common subtype of breast cancer. Resistance to endocrine therapy is a major clinical challenge. Although fulvestrant binds and degrades the ER and shows anti-tumor activity in patients with advanced breast cancer, intramuscular injection is inconvenient and precludes achievement of higher and potentially more efficacious exposure. ZN-c5 is a novel, orally bioavailable SERD with high potency and has demonstrated activity in estrogen-dependent tumor models. Methods: This Phase 1/2, open-label, multicenter study is evaluating the safety, pharmacokinetics and preliminary anti-tumor activity of ZN-c5 as monotherapy or in combination with palbociclib. In the Phase 1 portion evaluating ZN-c5 as monotherapy, participants were adult, post-menopausal (or receiving a gonadotropin-releasing hormone agonist) women with advanced adenocarcinoma of the breast, ER+/HER2- disease, and sensitive to endocrine therapy for metastatic disease (partial response [PR], complete response or stable disease [SD] lasting &gt; 6 months or disease recurrence after at least 24 months of adjuvant endocrine treatment). ZN-c5 was administered orally and continuously in 28-day cycles until disease progression or unacceptable toxicity. Dose escalation cohorts of subjects were enrolled at several dose levels of ZN-c5, based on a modified 3+3 design. Enrollment in the Phase 1 ZN-c5 monotherapy dose escalation and expansion has been completed and results are presented. Phase 1 testing of ZN-c5 in combination with palbociclib and Phase 2 testing in monotherapy are ongoing and will be presented at a future meeting. Results: In Phase 1 monotherapy, a total of 56 female subjects were enrolled to receive ZN-c5 at dose levels of 50 mg once daily (QD, n=16), 75 mg QD (n=3), 100 mg QD (n=3), 75 mg twice daily (BID, n=6), 150 mg QD (n=15), 150 mg BID (n=3), or 300 mg QD (n=10). Median age was 58.5 years (range, 38 - 89) and ECOG performance status was 0 (55%) or 1 (45%). Subjects had a median of 2 prior therapies for advanced/metastatic disease (range, 0 - 9), with a median of 2 prior hormonal-based therapies (range, 0 - 6) and a median of 0 prior chemotherapies (range, 0 - 3). Twenty-six subjects (46%) received prior fulvestrant and 38 (68%) received a prior CDK4/6 inhibitor. Twenty subjects (38%) had a baseline ESR1 mutation. The cut-off date for this analysis was 11 May 2021. There was no increase in severity of treatment-emergent adverse events (TEAEs) with increase in dose level. No dose-limiting toxicities were reported. The most common TEAEs were nausea (30%), fatigue (25%), and arthralgia (20%). Grade 3 TEAEs reported in &gt; 1 subject were gamma-glutamyltransferase (GGT) increased and hyponatremia (2 subjects each); no Grade 4 TEAEs were reported. Among treatment-related events, the most common were hot flushes and nausea (14% each); the only Grade 3 events were GGT increased and hypersensitivity in 1 subject each. ZN-c5 was rapidly absorbed, with a median Tmax of 2 to 4 hours. AUC and Cmax on Days 1 and 15 were less than dose proportional. No ZN-c5 accumulation after 15 days of dosing was observed. Confirmed PRs have been observed in 2 subjects (at 150 and 300 mg QD, respectively), and 14/45 (31%) evaluable subjects have experienced clinical benefit (PR or SD ≥ 24 weeks). Five of the 14 subjects with long SD received prior fulvestrant. Median progression-free survival (PFS) was 3.8 months (95% CI: 3.2, 5.3). Conclusions: In this first-in-human study, ZN-c5 monotherapy was well tolerated and showed clinical benefit, including confirmed PRs, in subjects with advanced ER+/HER2- breast cancer. These data warrant further evaluation of ZN-c5 as monotherapy and in combination with palbociclib.

Citation Format: Kevin Kalinksy, Vandana Abramson, Pavani Chalasani, Hannah M. Linden, Jasmina Alidzanovic, Rachel M. Layman, Živko Vranješ, Julie R. Nangia, Katherine D. Crew, Zoran Andric, Marijana Milovic-Kovacevic, Jasna Trifunovic, Jose Suarez, Matt Suster, Mieke Ptaszynski, Joanne Mortimer. ZN-c5, an oral selective estrogen receptor degrader (SERD), in women with advanced estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2 negative (HER2-) 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 P1-17-02.

Abstract P1-10-05: Evidence that body mass index modifies breast tissue collagen peptide response pattern to treatment with the non-steroidal anti-inflammatory drug sulindac

Background. In observational studies, regular use of non-steroidal anti-inflammatory drugs (NSAIDs) is associated with reduced breast cancer risk and disease recurrence with evidence that the benefit is greater in overweight/obese women. This parallels findings that obesity is associated with an increase in proinflammatory processes with possible effects on the breast stroma and extracellular matrix. Methods. To assess if body mass index (BMI kg/m2) alters breast tissue response to NSAIDs, we conducted exploratory analyses of change in breast tissue collagen-associated peptides following 6 months of treatment with the NSAID sulindac (150 mg bid) by BMI category: normal (18.5-24.9 n=6), overweight (25-29.9 n=14) and obese (≥30 n=11). Samples for this study were non-cancer core needle breast biopsies from postmenopausal women with a history of hormone receptor positive breast cancer enrolled to study sulindac effect on breast tissue biomarkers. At completion, 36 of 50 patients underwent baseline biopsy and 31 had sufficient tissue for paired analyses. Tissue collagen-associated peptides were studied using whole slide tissue imaging mass spectrometry proteomics. Individual peptide signals were normalized to total ion current and mean peak intensity per area across the entire biological specimen were used to generate a score per patient. Change in stroma peptides was evaluated by BMI status using the Wilcoxon matched pairs signed rank test. Unsupervised hierarchical clustering and heatmap visualization were used to assess differential expression of the peaks. Results. Approximately, 550 peptide peaks were found by targeted collagen tissue imaging proteomics. Striking differences in response to sulindac were observed by BMI. In overweight patients, 6 peptides related to COL1A1, COL6A1, COL6A3 and VIM on database matching differed significantly before and after sulindac treatment. Three were also altered in obese women. Two of the peptides overlapped 10 peptide changes identified in unstratified analyses reported in a separate submitted abstract on the main effect of sulindac on tissue collagen. Interestingly, these peptides were not altered in patients with normal BMI. In addition, on study 15 patients experienced a decrease in BMI and 12 experienced an increase. Two collagen peptides showed inverse relationships dependent on change in BMI status during the study. Conclusion. Six-month treatment with the non-selective NSAID sulindac was associated with changes in collagen-associated peptide differently by BMI status and by weight change. Our findings are most consistent with changes in post-translational hydroxylated proline modifications of collagen variation in the triple helical region. Ongoing work may provide insights on inflammation/adiposity-associated inflammation and effects on breast tissue collagen.

Citation Format: Denys Rujchanarong, Peggi M. Angel, Alison Stopeck, Christina Preece, Pavani Chalasani, Patricia A. Thompson. Evidence that body mass index modifies breast tissue collagen peptide response pattern to treatment with the non-steroidal anti-inflammatory drug sulindac [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-10-05.

Abstract P5-17-12: First-in-human expansion study of oral PMD-026 in metastatic triple negative breast cancer patients

Background: Durably effective therapeutic options remain elusive for metastatic triple negative breast cancer (mTNBC) patients. RSK is a novel target kinase for mTNBC, given its integral role in the MAPK/PDK-1 pathways. PMD-026, uniquely developed for TNBC, is a first-in-class, potent, oral RSK inhibitor that constitutes a promising avenue of treatment for mTNBC. PMD-026 demonstrated a favorable safety profile and initial signs of clinical benefit in metastatic breast cancer patients in Phase I. The current expansion is investigating PMD-026 in mTNBC patients whose disease has progressed on standard therapy. Methods: This open-label study evaluates the safety and efficacy of single agent PMD-026 in mTNBC patients. Target accrual for this study is a minimum of 20 mTNBC patients dosed at 200 mg q 12 hours who have measurable disease. A food effect (FE) sub-study is enrolling a total of 12 patients with a two-arm crossover design. Exploratory biomarker analysis of tumor tissue is being assessed for activated RSK2 levels. Exploratory objectives are to understand TNBC heterogeneity, with a view to identify patients who may benefit from PMD-026 optimally. Results: Based on the trial results thus far from 25 patients, PMD-026 continues to be well-tolerated with no G4 treatment-related adverse events. The noted toxicities include low incidence of elevated ALT/AST, rash, colitis or low-grade nausea. There has been no hair loss, myelosuppression or peripheral neuropathy. Given that TNBC is such a heterogeneous disease, we sought to identify subsets of patients with extensive prior therapy (≥ 5 lines) who may benefit from PMD-026 as a monotherapy. Based on ongoing analyses in the Phase I and Ib, patients diagnosed with TNBC at their initial diagnosis (de novo TNBC) stayed on study 3-4 times longer than patients who were initially treated for HR+ or HER2+ breast cancer but lost HR or HER2 expression to become TNBC (secondary TNBC). In addition, de novo TNBC patients treated at the recommended phase II dose (RP2D) of 200 mg BID with an H score for RSK2 ≥ 180 had a median progression free survival (PFS) of 3.3 months (n=3). In contrast, patients with an H score &lt; 180 had a median PFS of 0 months (n=3). Furthermore, the PFS of 3.3 months on PMD-026 is longer than the PFS of 1.7 months in a similar population of TNBC patients on chemotherapy, where the average number of prior treatments was 3a. . Conclusions: Updated safety, clinical activity, PK, and biomarker analyses will be presented. Clinical trial information: NCT04115306.aBardia et al, N Engl J Med 2021; 384:1529-154

Citation Format: Muralidhar Beeram, Judy S. Wang, Lida A. Mina, Pavani Chalasani, Rebecca A. Shatsky, Robert Wesolowski, Sara A. Hurvitz, Meghna S. Trivedi, Hyo S. Han, Amita Patnaik, My-my Huynh, Aarthi Jayanthan, Mary Rose Pambid, Lambert Yue, Gerrit Los, Sandra E. Dunn, Andrew Dorr. First-in-human expansion study of oral PMD-026 in metastatic triple negative breast cancer patients [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 P5-17-12.

Abstract PD6-04: Mutational landscape and immune infiltration of breast cancer metastases to gynecologic and other organs

Introduction: Breast cancer metastases (BCM), which cause most breast cancer (BC)-associated mortality, have increased genetic complexity compared to early-stage disease. However, the contribution of genetic alterations to site of BCM is not well-understood. Different breast cancer subtypes have varying patterns of BCM, e.g., lobular carcinoma more frequently spreads to gynecologic (Gyn) organs and the GI tract, perhaps hinting at selection pressures wherein some organs are hospitable to tumors with certain genetic alterations. Methods: Relationships between BCM site and mutations detected by DNA next-generation sequencing (NGS; NextSeq 592 gene panels or NovaSeq whole exome sequencing) were investigated using 12,464 BC samples sequenced at Caris Life Sciences (sample sizes, Table 1). PD-L1 expression was tested through IHC (Clone SP-142 (cut-off ≥1, 1%)). Tumor mutational burden (TMB) was measured by totaling somatic mutations per tumor (high ≥ 10 mutations per MB). Immune cell fractions were calculated by deconvolution of whole-transcriptome data (NovaSeq) using Quantiseq (reference). Statistical significance was determined using chi-square and Wilcoxon rank sum tests adjusted for multiple comparisons. Results: Compared to primary breast tumors, BCM had increased frequency of TMB-H (10.08% vs. 4.94%), decreased PD-L1 positivity (21.09% vs. 35.82%), and were enriched for PIK3CA (34.62% vs 30.53%) and ESR1 mutations (13.34% vs 2.17%) (all P&lt;0.001). PD-L1 positivity was highest in BCM to lymph nodes (43.06%) and axilla (39.77%). BCM to Gyn organs had more lobular histology, the highest rate of hormone receptor (HR)+ tumors (77.17%), and rarely had high TMB (6.73%) or were PD-L1 positive (11.39%). Double dendrogram hierarchical clustering of BCM site by mutation frequency and pathway alterations revealed BCM to Gyn organs as a simplicifolious clade with a unique mutational pattern. Compared to BC in breast, BCM to Gyn organs had higher rates of mutations of PIK3CA, AKT1, and BRAF; more mutations in DNA repair (0.79% vs 0.06%), transcription factor (4.72% vs 0.93%), and Wnt signaling pathways (2.36% vs 1.47%); but no increase in BRCA mutations. BCM to brain had the most p53 pathway and homologous recombination (HR) pathway mutations (64.71% and 14.01%), while Gyn had the least (19.69% and 7.09%). Quantiseq RNA deconvolution revealed differences in tumor immune cell infiltrate by BCM site. Gyn metastases vs breast tumors had increased B cells (6.20% vs 5.40%), M2 macrophages (5.71% vs 4.07%), and NK cells (3.82% vs 3.18%) (all P&lt;0.01) and a M2/M1 macrophage ratio of 22.8:1 vs 1.3:1. Conclusions: BCM to Gyn organs have a unique mutational and immune suppression profile. Integrating the profiling with clinical outcomes may extend this prognostic signature and set the stage for improved treatment strategies for these patients. Confirmation from matched or sequential specimens could clarify tumor evolution. Our data support repeat biopsy of Gyn site metastases since more targetable mutations might be revealed. Targeting mechanisms of immunosuppression in Gyn BCM could expand therapeutic options.

Table 1.Breast Cancer TumorsTumor SiteTotalPredominant Breast Cancer SubtypeAll12464HR+/HER2- (51.6%)Breast5014HR+/HER2- (46.5%)Liver2003HR+/HER2- (63.3%)Bone1132HR+/HER2- (69.4%)Axilla1051HR+/HER2- (47.7%)Lung823HR+/HER2- (46.1%)Lymph Node647HR+/HER2- (43.4%)Chest/Chest Wall375HR+/HER2- (44.8%)Brain359TNBC (38.2%)Other315HR+/HER2- (57.1%)Skin282HR+/HER2- (50.7%)Connective Tissue193HR+/HER2- (51.8%)GI Organs143HR+/HER2- (69.9%)Gynecologic Organs127HR+/HER2- (76.4%)

Citation Format: Anna D Louie, Rani Chudasama, Sharon Wu, Marzia Capelletti, Daniel Magee, W. Michael Korn, Virginia Kaklamani, Antoinette R Tan, Pavani Chalasani, Wafik S El-Deiry, Don Dizon, Stephanie L. Graff. Mutational landscape and immune infiltration of breast cancer metastases to gynecologic and other organs [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 PD6-04.

Abstract GS3-10: Study of samuraciclib (CT7001), a first-in-class, oral, selective inhibitor of CDK7, in combination with fulvestrant in patients with advanced hormone receptor positive HER2 negative breast cancer (HR+BC)

Background: CDK7 inhibition is a promising therapeutic strategy in cancer; acting as a regulator of the cell cycle, transcription and endocrine receptor signalling [1]. Patients with HR+BC post CDK4/6 inhibitor treatment have a poor prognosis; median progression free survival (mPFS) of ~ 8 weeks for fulvestrant post CDK4/6i in HR+BC [2,3]. Pre-clinical HR+BC models indicate the potential for synergy when the CDK7 inhibitor samuraciclib is combined with the Selective Estrogen Receptor Degrader fulvestrant [4]Materials and Methods: This single arm cohort assessed the tolerability and efficacy of samuraciclib in combination with standard dose fulvestrant in patients with advanced HR+BC; all patients had previously received an aromatase inhibitor and a CDK4/6i for advanced disease.Results: 31 patients with HR+BC received the combination of standard dose with fulvestrant and samuraciclib. 6 patients received samuraciclib dose of 240mg once daily (QD) and 25 patients a dose of 360mg QD. The combination treatment was generally well tolerated, with adverse drug reactions (AE) of note being G1-2 nausea, vomiting and diarrhoea; the majority of patients staying on treatment until disease progression.RECIST evaluation indicates evidence of reduction in tumor disease burden, including a partial response in one patient who has been on treatment for ~ 1 year.Graphic illustrations of data, including ‘waterfall’ and ‘swimmer’ plots, will be presented along with stratification data based on demographic factors such as hepatic involvement and cfDNA analysis (ESR1m, PI3Km).Conclusions: Samuraciclib has demonstrated an acceptable safety profile with evidence of anti-tumour activity in combination with fulvestrant for patients with advanced HR+BC who have progressed on their prior CDK4/6i.References:1.Patel et al., Mol Cancer Therap. 20182.Juric et al., SABCS 20183.Lindeman et al., JCO 20214.Jeselsohn et al., SABCS 2019

Citation Format: Charles Coombes, Sasha J Howell, Matthew G Krebs, Simon Lord, Laura M Kenny, Ash Bahl, Glen Clack, Edward Ainscow, Paul A Dickinson, Raluca Fostea, Janine Mansi, Carlo Palmieri, Gianflippo Bertelli, Rinath Jeselsohn, Zahi Mitri, William J Gradishar, Sagar Sardesai, Joyce O'Shaughnessy, Patrick Ward, Pavani Chalasani, Manfred Lehnert, Simak Ali, Stuart McIntosh. Study of samuraciclib (CT7001), a first-in-class, oral, selective inhibitor of CDK7, in combination with fulvestrant in patients with advanced hormone receptor positive HER2 negative breast cancer (HR+BC) [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 GS3-10.

Sulindac Improves Stiffness and Quality of Life in Women Taking Aromatase Inhibitors for Breast Cancer

PURPOSE

To examine benefit of sulindac for relief of musculoskeletal symptoms (MSS) in patients stable on aromatase inhibitors (AIs).

METHODS

Sulindac was evaluated at 150 mg twice daily for effects on MSS at 3, 6, 9, and 12 months in 50 postmenopausal women stable on AI therapy for a median of 12.5 months for hormone receptor-positive breast cancer. A separate, non-randomized group of 50 similar patients was observed for change in MSS over 12 months. MSS severity was assessed using the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index and Brief Pain Inventory Short Form (BPI-SF). The Functional Assessment of Cancer Therapy-General form (FACT-G) measured quality of life (QOL). Change in MSS and QOL across time was assessed in each group using linear mixed effects models.

RESULTS

Stiffness, not pain, was the main complaint at baseline. At 12 months, sulindac patients reported decreases (improvements) in mean (95% CI) Total WOMAC score [- 5.85 (- 9.73, - 1.96)] and WOMAC pain [- 5.40 (- 10.64, - 0 .18)], Stiffness [- 9.53 (- 14.98, - 4.08)] and Physical Function [- 5.61 (- 9.62, - 1.60)] subscales, but not BPI-SF worst pain. Among sulindac patients with higher baseline MSS severity, 35% experienced ≥ 50% improvement in Total WOMAC and Total FACT-G scores [6.18 (2.08, 10.27); P = 0.003]. For the observation group, MSS and QOL did not improve over 12 months, even among those with higher baseline MSS severity.

CONCLUSIONS

Sulindac may relieve MSS in AI patients, especially physical function and stiffness. Randomized controlled trials should further evaluate NSAIDs on AI-MSS and AI adherence.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

NCT01761877, December, 2012.