Dueck, Amylou C.

390216 Background: CDK4/6 inhibitors have become standard of care for advanced hormone receptor positive, HER2-negative (HR+/HER2-) breast cancer in combination with endocrine therapy (ET), with one approved for high-risk patients (pts) in the adjuvant setting. The PALLAS Trial investigated the addition of palbociclib to adjuvant ET in pts with stage II-III breast cancer. Stage IIA patients were specifically enrolled to evaluate the potential benefit of using palbociclib with adjuvant ET pts diagnosed at lower risk who may have more indolent disease. Methods: In the prospective, randomized, phase III PALLAS trial, pts with HR+/HER2- early breast cancer were randomly assigned to receive adjuvant ET for at least 5 years with or without 2 years of palbociclib (125 mg orally once daily, days 1-21 of a 28-day cycle). ET was of provider’s choice. Stage IIA enrollment was capped at 1,000 patients. While the primary end point of the overall study was invasive disease-free survival (iDFS) for the entire cohort, there was a preplanned analysis of recurrence and survival endpoints in the stage IIA cohort. Outcomes were compared between arms using stratified log-rank tests and Cox models (stratification factors: chemotherapy and age ≤ 50). Results: Among 5,796 pts enrolled at 406 centers in 21 countries worldwide between 9/1/2015 and 11/30/2018, a total of 1,010 stage IIA pts were enrolled. The protocol-defined number of events occurred at a median follow-up of 50 months for this subgroup (43.1 months for the overall study). Median age within this subgroup was 54 (range 29-85 yrs), and 410 (40.6%) were pre/perimenopausal, 506 (50.1%) T2/N0 (vs T0-1/N1), 272 (26.9%) grade 3 (vs. grade1/2), and 561 (55.5%) received chemotherapy. iDFS events occurred in 31 of 503 (6.2%) pts who received palbociclib plus ET and in 45 of 507 (8.9%) pts who received ET alone, resulting in a statistically nonsignificant difference in iDFS at 4 years (92.9% vs. 92.1%; hazard ratio, 0.75; CI, 0.48 to 1.19; P = .23). Nonsignificant differences were also observed for invasive breast cancer-free, distant recurrence-free, and locoregional cancer-free survival. No significant differences in iDFS were observed in subgroups including age group, receipt of chemotherapy, tumor grade, and clinical risk (T1/N1 vs. T2/N0).Conclusions: In this preplanned analysis of the stage IIA cohort of the PALLAS trial, the addition of adjuvant palbociclib to standard ET did not improve outcomes over ET alone, suggesting no benefit from the agent in reducing the incidence of early relapse in pts with lower-stage HR+/HER2- breast cancer. Future analyses will incorporate genomic risk and other molecular patterns from the extensive transPALLAS correlative program. Additional follow-up (10-year minimum) is also underway to assess the impact of palbociclib exposure on late recurrence in HR+ disease. Clinical trial information: NCT02513394.

180 Background: Financial toxicity affects 20% of cancer survivors and is associated with decreased treatment adherence and poor clinical outcomes. No large-scale programs have been implemented to mitigate financial toxicity among patients undergoing cancer treatment. We evaluated the effect of monthly patient-reported financial toxicity screening as part of a larger digital monitoring intervention. Methods: PRO-TECT (AFT-39) is a cluster-randomized trial of patients undergoing systemic therapy for metastatic cancer. Practices were randomized 1:1 to digital symptom monitoring with patient-reported outcomes (“PRO practices”) or usual care (“control practices”). Digital monitoring consisted of between-visit online or automated telephone patient surveys containing symptom, functioning, and financial toxicity screening questions for up to one year, with automated alerts sent to practice nurses for concerning survey scores. Clinical team actions in response to alerts were not mandated. The primary outcome of this analysis was development or worsening of financial difficulties, assessed via the EORTC QLQ-C30 (“Has your physical condition or medical treatment caused you financial difficulties?”), at any time compared to baseline. A randomly selected subset of patients and nurses were interviewed about their experiences with the intervention. Results: 1,191 patients were enrolled (593 PRO; 598 control) at 52 US community oncology practices. Overall, 30.2% of patients treated at practices that received the intervention developed, or experienced worsening of, financial difficulties, compared to 39.0% of patients treated at control practices (p = 0.01). Patients and nurses interviewed stated that financial toxicity screening identified patients for financial counseling who otherwise would be reluctant to seek, or unaware of the availability of, assistance. Conclusions: Screening for financial toxicity as part of routine digital patient monitoring with PROs reduces the development, or worsening, of financial difficulties among patients undergoing systemic cancer therapy. Clinical trial information: NCT03249090.

8504 Background: The CALGB 30610 trial demonstrated that 70Gy QD TRT was not associated with a superior overall survival compared to standard BID 45Gy TRT in limited stage small cell lung cancer. Since both arms appeared to provide similar clinical benefit, other factors such as quality of life may help oncologists decide on the best treatment approach for their patients. The present analysis was conducted to compare patients’ quality of life between these regimens in terms of their physical symptoms, physical functioning and psychological state. Methods: In the CALGB 30610 planned sub-study CALGB 70702, patients were administered the FACT-L, FACT Trial Outcome Index-Lung Cancer (FACT-L TOI), FACT-Esophageal Cancer Eating and Swallowing Indices, ECOG Acute Esophagitis Scale, Hospital Anxiety and Depression Scale (HADS), the EQ-5D at baseline and a single item assessing difficulty swallowing at baseline, 3, 5, 7, 12, 26, and 52 weeks after starting radiation therapy. Patients were also asked to assess treatment inconvenience at these time points. The primary endpoints of CALGB 70702 were FACT-L TOI and FACT eating and swallowing subscales at 12 weeks. Mean changes from baseline were compared between arms using general linear mixed models. Results: 417 patients consented to participate in the patient-reported outcomes substudy. The completion rate of the questionnaires was 87% at baseline and 71% at week 52. The FACT-L total score mean worsening was significantly less in the QD arm compared to the BID arm at week 3 (-1.0 vs -7.0; P=.003), and marginally less at week 5 (-5.3 vs -11.0; P=.06). The FACT-L TOI mean worsening was significantly less in the QD arm than in the BID arm at week 3 (-2.9 vs -7.6; P=.003) and greater at week 12 (-7.6 vs -2.8; P=.03). The QD arm also had a lesser EQ-5D index mean worsening at 3 weeks (-0.04 vs 0.03; P=.002). Mean increase in the acute esophagitis score (1.06 vs 2.89; P<.001) and difficulty swallowing (0.39 vs 1.14; P<.001) were significantly greater in the BID arm at week 3. Mean worsening in HADS anxiety was significantly less in the QD arm at week 5 (-1.99 vs -0.95; P=.03). There were no other significant differences at the remaining timepoints between the two arms. Across visits on the QD arm, patients felt that treatment was inconvenient at 26% (96/376) assessments, compared to 33% (116/352) in the BID arm (chi-sq P=.03). Conclusions: Both radiation regimens were well tolerated. However, the QD arm had better quality of life scores at week 3 and was perceived to be less inconvenient. Clinical trial information: NCT00632853.

e19078 Background: Patients with myeloproliferative neoplasms (MPN), including polycythemia vera (PV), essential thrombocythemia (ET), and myelofibrosis (MF), experience chronic disease-related symptoms. Surveying these patients while incorporating the MPN-Symptom Assessment Form (SAF) gains valuable insight. Independent surveys evaluating symptoms among MPN patients have seen disproportionate participation among females compared to males (upwards of 4:1). Though the general MPN patient population is roughly gender balanced, epidemiological studies show the occurrence of MPN types differ between men and women (MPN [%male]: PV [65%], ET [33%], MF [50%]. Mehta, et al. Leuk & Lymph 2014). In-clinic evaluations and international MPN surveys of disease-related symptoms suggest women report higher symptom burden on average compared to men, despite MPN type [Emanuel, et al. JCO 2012. Geyer, et al. Haematol 2017]. Further, a recent study across cancer trials showed women had a 34% increased risk of reporting severe symptoms [Unger, et al. JCO 2022]. This study aimed to evaluate gender imbalance in survey participation among MPN patient surveys and investigate its potential to overestimate symptom burden if gender is ignored. Methods: Five anonymous web-based surveys were used to assess the impact of disproportionate gender participation. The MPN-10 assessing the 10 most clinically meaningful SAF items was present in these surveys and generated the Total Symptom Score (TSS). Survey responses with no self-reported gender or ≥5 missing MPN-10 symptoms were excluded. Raking weights based on expected MPN population were applied at the survey- and MPN type-level. Relative bias of mean TSS was calculated to evaluate over- and underestimation due to this participation imbalance. Relative bias <5% is commonly acceptable. Results: There were 4962 survey participants total and 74% were female (Table). Epidemiologically expected gender frequency by MPN type was not seen (MPN [%male]: PV [31%], ET [15%], MF [37%]). The gender participation imbalance accounted for a 3.1% overestimation of overall TSS. This also resulted in a 6.8% underestimation of the mean difference in TSS between genders, across MPNs. Conclusions: Overall bias due to gender participation imbalance was relatively low. However, analyses considering gender differences were more impacted. Anonymous surveys should seek to reduce participation bias during the survey design phase. More research is needed to evaluate gender and other participation biases in surveys across cancer domains.[Table: see text]

TPS5107 Background: Despite a growing number of treatment options for first line mCRPC, approximately 40% of patients (pts) have radiographic progression within the first year. Androgen receptor (AR) signaling inhibition increases genomic instability with double-strand DNA breaks & co-inhibition of AR & PARP induces synthetic lethality in multiple preclinical models. Homologous recombination repair (HRR) gene aberrations do not appear to be necessary for this synergy as demonstrated in a ph 3 clinical trial of abiraterone & olaparib where this combination improved radiographic progression-free survival (rPFS) in HRR-wild-type pts compared with abiraterone alone. A ph 1b trial has since shown that enzalutamide plus rucaparib has acceptable safety profile & no significant drug-drug interactions (S-DDI). Methods: CASPAR/A031902 (NCT04455750) is a ph 3 study in which 984 pts will be randomized 1:1 to enzalutamide plus rucaparib or placebo. HRR gene aberration is not required for enrollment. All pts will undergo next-generation targeted-exome sequencing from archival tumor tissue (new biopsy only required if no archival tissue available). Treatment will be continued until disease progression & crossover is not allowed. Key eligibility criteria are age ≥ 18 years, ECOG PS 0-2, biopsy-proven prostate adenocarcinoma, progressive (PSA or radiographic) disease per Prostate Cancer Working Group 3 guidelines, measurable or nonmeasurable disease per RECIST 1.1, no prior treatment for mCRPC (prior docetaxel, abiraterone, darolutamide, or apalutamide in non-mCRPC setting is allowed), no significant uncontrolled comorbidity, & no medications with S-DDI with enzalutamide/rucaparib. Hierarchical co-primary endpoints are rPFS & overall survival (OS). The OS analysis will be undertaken as a primary endpoint if the rPFS endpoint is met. For a one-sided logrank test with a type 1 error rate equal to 0.025, the study has 90% power to detect a hazard ratio (HR) of 0.71 in rPFS (median rPFS of 15 & 21 months in control & combination arms, respectively) & 80% power to detect an HR of 0.80 in OS (median OS of 32 & 40 months, respectively). Key secondary endpoints are rPFS & OS in pts with vs without pathogenic BRCA1, BRCA2, or PALB2 alterations; & differences in adverse events & quality of life (QOL) outcomes between the treatment arms. QOL assessments include Functional Assessment of Cancer Therapy–Prostate (FACT-P), Brief Pain Inventory Short Form (BPI-SF) & EQ-5D-5L. A key correlative endpoint is the sensitivity of ctDNA-based testing for alterations in HRR genes. Enrollment to CASPAR began in July 2021 & the study is available for participation to all US-NCTN sites with a projected enrollment of 3 years. Support: U10CA180821, U10CA180882, U24CA196171; U10CA180888. Clinical trial information: NCT04455750.

518 Background: Body Mass Index (BMI) impacts breast cancer risk and prognosis. Conflicting results have been published regarding BMI as a predictive factor for endocrine therapy benefit. CDK4/6 inhibitors (CDK4/6i) in combination with endocrine treatment (ET) are standard-of-care treatments for metastatic hormone receptor-positive breast cancer. In contrast to cytotoxic chemotherapy, CDK4/6i are given at a fixed dose irrespective of BMI or weight. The PALLAS trial compared the combination of the CDK4/6i palbociclib and adjuvant ET to ET alone in the early breast cancer setting. This analysis investigates the impact of BMI on the efficacy and the side effect profile of palbociclib (P) in the PALLAS trial. Methods: In this pre-planned analysis, patients (pts) enrolled in PALLAS were categorized according to BMI as underweight (BMI <18.5 kg/m2), normal weight (BMI 18.5-24.9 kg/m2), overweight (BMI 25-29.9 kg/m2) and obese (³30 kg/m2), respectively. Adverse event differences were assessed with Chi-squared tests. Time to early discontinuation of P was analyzed with Fine and Gray competing risk models. Cox models were used to investigate the association between BMI category and time to invasive disease-free survival (iDFS). Results: Of a total of 5698 pts included in this analysis, 68 (1.2%) were underweight, 2082 (36.5%) normal weight, 1818 (31.9%) overweight and 1730 (30.4%) obese at baseline. Significantly different rates of all grade neutropenia were observed in normal weight, overweight and obese pts with regard to total (88.5%, 85.7% and 74.7%), as well as grade 3 (64.1%, 62.0% and 43.9%) and grade 4 neutropenia (7.0%, 3.6% and 2.0%), respectively. The lower frequency and severity of neutropenia observed in overweight and obese pts was associated with a significant lower treatment discontinuation rate over time when compared to normal weight patients (overweight vs normal weight: HR 0.73 CI 0.63-0.84, p<0.0001, and obese vs normal weight: HR 0.65 CI 0.56-0.75, p<0.0001). In pts treated with P, neutropenia was the primary toxicity leading to treatment discontinuation in 21.1% of normal weight pts, 14.0% of overweight pts and 5.9% obese pts, respectively. Despite these observations, there was no statistically significant improvement in iDFS with the addition of P to ET in any weight category (normal weight HR 0.84 CI 0.63-1.12, overweight HR 1.10 CI 0.82-1.49 and obese HR 0.95 CI 0.69-1.30). Conclusions: This pre-planned analysis of outcomes by BMI in the PALLAS trial demonstrates significantly less frequent and less severe neutropenia in overweight and obese pts compared to those with normal weight, leading to significant lower treatment discontinuation rates. However, no difference in iDFS outcomes by BMI was observed. Additional long-term follow-up will further evaluate whether BMI ultimately impacts outcome. Clinical trial information: NCT02513394.