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PURPOSE Palbociclib is a cyclin-dependent kinase 4 and 6 inhibitor approved for advanced breast cancer. In the adjuvant setting, the potential value of adding palbociclib to endocrine therapy for hormone receptor–positive breast cancer has not been confirmed. PATIENTS AND METHODS In the prospective, randomized, phase III PALLAS trial, patients with hormone receptor–positive, human epidermal growth factor receptor 2–negative early breast cancer were randomly assigned to receive 2 years of palbociclib (125 mg orally once daily, days 1-21 of a 28-day cycle) with adjuvant endocrine therapy or adjuvant endocrine therapy alone (for at least 5 years). The primary end point of the study was invasive disease-free survival (iDFS); secondary end points were invasive breast cancer–free survival, distant recurrence-free survival, locoregional cancer-free survival, and overall survival. RESULTS Among 5,796 patients enrolled at 406 centers in 21 countries worldwide over 3 years, 5,761 were included in the intention-to-treat population. At the final protocol-defined analysis, at a median follow-up of 31 months, iDFS events occurred in 253 of 2,884 (8.8%) patients who received palbociclib plus endocrine therapy and in 263 of 2,877 (9.1%) patients who received endocrine therapy alone, with similar results between the two treatment groups (iDFS at 4 years: 84.2% v 84.5%; hazard ratio, 0.96; CI, 0.81 to 1.14; P = .65). No significant differences were observed for secondary time-to-event end points, and subgroup analyses did not show any differences by subgroup. There were no new safety signals for palbociclib in this trial. CONCLUSION At this final analysis of the PALLAS trial, the addition of adjuvant palbociclib to standard endocrine therapy did not improve outcomes over endocrine therapy alone in patients with early hormone receptor–positive breast cancer.

PURPOSE A large-panel gene expression analysis was conducted to identify biomarkers associated with the effectiveness of adding palbociclib to fulvestrant. METHODS The PALOMA-3 (ClinicalTrials.gov identifier: NCT01942135 ) trial randomly assigned 521 endocrine-pretreated patients with metastatic breast cancer to receive palbociclib plus fulvestrant or placebo plus fulvestrant. Primary analysis was first conducted on 10 genes on the basis of pathway biology and evidence from previous studies followed by a systematic panel-wide search among 2,534 cancer-related genes. The association of gene expression with the effect of palbociclib on progression-free survival (PFS) was evaluated using Cox proportional hazards regression analysis, with gene expression as a continuous variable or dichotomized by median. An independent breast cancer cohort from the Preoperative Palbociclib (POP) Clinical Trial (ClinicalTrials.gov identifier: NCT02008734 ) was used for validation, in 61 patients with primary breast cancer treated with 2 weeks of palbociclib. RESULTS In the PALOMA-3 trial, 302 patients had tumor tissue analyzed (palbociclib arm, 194 patients; placebo arm, 108 patients). Palbociclib efficacy was lower in patients with high versus low cyclin E1 ( CCNE1) mRNA expression (median PFS: palbociclib arm, 7.6 v 14.1 months; placebo arm, 4.0 v 4.8 months, respectively; interaction P unadjusted = .00238; false discovery rate–adjusted P = .0238). CCNE1 mRNA was more predictive in metastatic than in archival primary biopsy tissue samples. No significant interaction was found between treatment and expression levels of CDK4, CDK6, cyclin D1, and RB1. Palbociclib was efficacious in both luminal A and luminal B tumors. High CCNE1 mRNA expression was associated with poor antiproliferative activity of palbociclib in the POP trial ( P = .005). CONCLUSION Addition of palbociclib to fulvestrant demonstrated efficacy in all biomarker groups, although high CCNE1 mRNA expression was associated with relative resistance to palbociclib.

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 2), 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

A MESSAGE FROM ASCO’S PRESIDENT I remember when ASCO first conceived of publishing an annual report on the most transformative research occurring in cancer care. Thirteen reports later, the progress we have chronicled is remarkable, and this year is no different. The research featured in ASCO's Clinical Cancer Advances 2018 report underscores the impressive gains in our understanding of cancer and in our ability to tailor treatments to tumors’ genetic makeup. The ASCO 2018 Advance of the Year, adoptive cell immunotherapy, allows clinicians to genetically reprogram patients’ own immune cells to find and attack cancer cells throughout the body. Chimeric antigen receptor (CAR) T-cell therapy—a type of adoptive cell immunotherapy—has led to remarkable results in young patients with acute lymphoblastic leukemia (ALL) and in adults with lymphoma and multiple myeloma. Researchers are also exploring this approach in other types of cancer. This advance would not be possible without robust federal investment in cancer research. The first clinical trial of CAR T-cell therapy in children with ALL was funded, in part, by grants from the National Cancer Institute (NCI), and researchers at the NCI Center for Cancer Research were the first to report on possible CAR T-cell therapy for multiple myeloma. These discoveries follow decades of prior research on immunology and cancer biology, much of which was supported by federal dollars. In fact, many advances that are highlighted in the 2018 Clinical Cancer Advances report were made possible thanks to our nation’s support for biomedical research. Funding from the US National Institutes of Health and the NCI helps researchers pursue critical patient care questions and addresses vital, unmet needs that private industry has little incentive to take on. Federally supported cancer research generates the biomedical innovations that fuel the development and availability of new and improved treatments for patients. We need sustained federal research investment to accelerate the discovery of the next generation of cancer treatments. Another major trend in this year’s report is progress in precision medicine approaches to treat cancer. Although precision medicine offers promise to people with cancer and their families, that promise is only as good as our ability to make these treatments available to all patients. My presidential theme, “Delivering Discoveries: Expanding the Reach of Precision Medicine,” focuses on tackling this formidable challenge so that new targeted therapies are accessible to anyone who faces a cancer diagnosis. By improving access to high-quality care, harnessing big data on patient outcomes from across the globe, and pursuing innovative clinical trials, I am optimistic that we will speed the delivery of these most promising treatments to more patients. Sincerely, Bruce E. Johnson, FASCO ASCO President, 2017 to 2018

222 Background: As new tools for prognostic prediction and assessment of treatment response in breast cancer are developed, there is growing interest in treatment optimization strategies to reduce toxic therapy or add additional therapy as needed. The I-SPY 2 trial utilizes a new predictive tool “PreRCB,” which includes mid-treatment MRI and core biopsy responses, to identify patients likely to have a pCR (pathologic complete response) who can de-implement, or forgo, standard-of-care anthracycline-based chemotherapy (AC) after treatment with a taxane + investigational agent. This study assesses initial de-implementation eligibility and selection within the I-SPY2 trial. Methods: All patients enrolled in I-SPY2 since September of 2020 (when the preRCB protocol was first introduced to the trial) who completed the first treatment regimen were evaluated. Patients were only considered for de-implementation of AC if the mid-treatment biopsy was routed to site clinical pathology for review for residual invasive disease. In these patients, preRCB was determined to be predictive of pCR if there was 1) no invasive cancer on the core biopsy and 2) MRI findings met subtype-specific functional tumor volume criteria. Patients meeting criteria for predicted pCR could be offered the option to go directly to surgery by their provider, foregoing pre-operative AC, with the option to receive AC post-operatively should the surgical specimen reveal residual disease. The following outcomes (n,%) were descriptively evaluated: patients participating in I-SPY2, sites with at least one patient evaluated for de-implementation using pre-RCB, patients eligible for de-implementation, patients with surgical RCB assessment, and patients who de-implemented chemotherapy. Results: From September 2020 – May 2021, 145 patients were eligible for analysis. 9/20 (45%) sites with eligible I-SPY patients had at least one patient considered for preRCB assessment. Only 46 patients (32%) had clinical reads on their biopsies, as required for preRCB evaluation. Of these, 48% (14/29) of patients met both MRI and pathology criteria to de-implement AC. However, only seven (50%) of these patients chose to proceed to surgery without preoperative AC. Of those who did not have a predicted pCR using preRBC criteria, 87.5% (28/32) received AC as recommended by the protocol and 12.5% (4/32) did not receive preoperative AC. Conclusions: These pilot results demonstrate slow uptake of this strategy by patients and clinicians. We are currently interviewing patients and physicians to identify and assess facilitators and barriers for patients and physicians to pursue response-guided treatment regimes. Understanding these motivations will create the opportunity to engage site, providers, and patients to engage in research optimizing chemotherapy treatment. Clinical trial information: NCT01042379.

605 Background: Pts with TNBC who have residual invasive disease (RD) after completion of NAC have a very high risk for recurrence, which is reduced by adjuvant capecitabine (C). Pre-clinical models support the use of platinum agents (P) in the TNBC basal subtype. EA1131 tested the hypothesis that invasive disease-free survival (iDFS) would not be inferior but improved in pts with basal subtype TNBC after NAC with the adjuvant use of a P instead of C (primary objective). Methods: Pts with clinical stage II/III TNBC post neoadjuvant taxane +/- anthracycline-based chemotherapy with at least 1 cm RD in the surgical specimen were randomized (1:1) to receive P (carboplatin or cisplatin once every 3 weeks for 4 cycles) or C (14/7d every 3 weeks for 6 cycles). TNBC subtype (basal vs. non-basal) was analyzed in the surgical specimen by PAM50. A non-inferiority design (non-inferiority margin of hazard ratio [HR] of 1.154) with superiority alternative (alternative HR of 0.754) was chosen, assuming a 4-year iDFS of 67% for the C arm. Non-inferiority was tested first. If non-inferiority was shown, a formal test for superiority of P compared to C would be conducted. Results: 401 participants were randomized to P or C between 2015 and 2020 (recruitment goal, 775), 310 (77%) had TNBC basal subtype disease (primary analysis population). Pts’ median age was 52 years, 71% were White and 19% Black. At diagnosis, most tumors were high grade (78%), T2 (59%), 47% N0, and 40% N1. Residual tumors were 37% ypT1, 44% ypT2, and 47% ypN0. Overall incidence of any toxicity was similar (83% with P, 80% with C), but grade 3 and 4 toxicities (no grade 5) were more common with P (25% vs 15%). After median follow-up of 18 months, 113 iDFS events (58% of full information) had occurred. 3-year iDFS for P arm was 40% (95%CI, 29%-51%) and 44% (95%CI, 32%-55%) for C arm. The HR for arms P/C was 1.09 (95% Repeated Confidence Interval, 0.62-1.90) and the probability of eventually rejecting the null of inferiority (i.e., conditional power) was 6%. The Data Safety and Monitoring Committee recommended stopping the trial at the 5th interim analysis in March 2021 since it was unlikely that the trial would be able to show non-inferiority or superiority of the P arm. Conclusions: Participants with TNBC with RD after NAC had a lower than expected 3-year iDFS regardless of study treatment. Available data show that it is very unlikely that the study would be able to establish non-inferiority of P to C. In addition, severe toxicities were more common with P. In pts with TNBC, particularly basal subtype, with at least 1 cm RD after NAC and high-risk of recurrence, adjuvant P use does not improve outcomes. Correlative analyses of RD tissue (NGS), circulating markers (ctDNA and CTC pre/post treatment), and patient-reported outcomes (PRO) questionnaires will now occur. Clinical trial information: NCT02445391.

1000 Background: In PALOMA-3, a randomized, double-blind, placebo-controlled, phase 3 study, PAL+FUL significantly prolonged progression-free survival (PFS) compared with placebo (PBO) + FUL (1-sided P6 years of median follow-up in pts with HR+/HER2– ABC who had progressed on prior endocrine treatment. Pfizer (NCT01942135) Clinical trial information: NCT01942135 .[Table: see text]

519 Background: About one third of patients with hormone-receptor-positive (HR+), HER2‐ primary breast cancer with residual invasive disease after neoadjuvant chemotherapy will relapse despite adjuvant endocrine therapy. Therapeutic inhibition of cyclin-dependent kinase 4 and 6 (CDK 4/6) by palbociclib combined with endocrine therapy demonstrated highly relevant efficacy in metastatic breast cancer. The phase III PENELOPE-B (NCT01864746) study did not show a significant benefit from palbociclib in women with centrally confirmed HR+, HER2- primary breast cancer without a pathological complete response after taxane‐containing neoadjuvant chemotherapy and at high-risk of relapse (CPS‐EG score ≥3 or 2 and ypN+) for the primary endpoint (Loibl et al. JCO 2021). Methods: After completion of neoadjuvant chemotherapy and locoregional therapy, PENELOPE-B patients were randomized (1:1) to receive 13 cycles (1 year) of palbociclib 125mg daily or placebo on days 1-21 in a 28d cycle in addition to standard endocrine therapy. Analysis of the primary endpoint of invasive disease-free survival (iDFS) was planned after 290 events. Secondary objective included iDFS in luminal-B group by treatment. Gene expression in post-neoadjuvant surgical residual tumor tissue samples was profiled using the HTG EdgeSeq Oncology Biomarker Panel targeting 2559 genes (HTG Molecular Diagnostics Inc.). Based on 91 genes of this panel the AIMS subtype (Paquet & Hallett, JNCI 2014) was calculated. Results: Gene expressions were measured in tumors from 906 of 1250 (72%) PENELOPE-B patients; 663 had LumA subtype, 64 LumB, 135 NormL, 16 BasalL, and 28 HER2E. Compared to LumA the LumB patients were older, had higher post-neoadjuvant Ki-67, higher risk status (CPS-EG), and higher grade; no significant correlation was found for the region of participating sites, cT, ypT, and ypN. Patients with LumB tumors had an estimated 3-year iDFS of 71.9% with palbociclib vs 44.8% with placebo HR = 0.50 (0.24-1.05); outcome was similar in patients with LumA tumors (3-year iDFS 83.9% vs 79.5%, HR = 0.93 (0.68-1.28), interaction p = 0.132); this was confirmed in multivariable analyses. Ki-67 by IHC and proliferation biomarkers from the HTG panel also showed no significant interaction with treatment. Conclusions: PENELOPE-B did not show a benefit from the addition of 1 year palbociclib to endocrine therapy compared to placebo in the total enrolled high-risk primary breast cancer population. However, the small group of luminal-B tumors (n = 64) derived benefit from palbociclib, although without a statistically significant interaction. Further investigation is required in a larger cohort to validate a palbociclib benefit that might be confined to this group.

2008 Background: Enthusiasm for precision oncology may obscure the complex psychosocial and ethical considerations for tumor genetic testing. Low patient genetic knowledge has been documented and heightens the risk for adverse experiences. We developed a web-based intervention to increase genetic knowledge and decrease distress among advanced cancer patients undergoing tumor genetic testing. Methods: 594 patients (80% from NCORP Community Sites) were recruited and randomized to web-intervention (n = 293) or usual care (n = 301), prior to receipt of tumor genetic test results. Primary outcomes were genetic knowledge, anxiety, depression, and cancer-specific distress measured at T0 (prior to intervention), T1 (post-intervention), T2 (after receipt of tumor results) and T3 (3 months post receipt of tumor results). Secondary outcomes included satisfaction, regret and disappointment. The effect of web-intervention was evaluated using t-test, multiple linear regression and logistic regression, with an intent-to-treat approach. Results: Patients randomized to web-intervention had better knowledge improvement than those randomized to usual care (T1-T0, p < 0.0001; T2-T0, p = 0.003). No difference was observed in change scores for anxiety, depression or cancer-specific distress. To find the moderators of intervention effect (including sex, age, education, and literacy) two 2-way interactions were noted with statistical significance: higher depression among those in the intervention arm versus the control arm for patients with lower literacy (p = 0.03); and lower cancer-specific distress among women in the intervention arm than with usual care but no such effect noted in men (p = 0.01). 71% of patients reported receiving tumor test results and this did not differ by arm. Only 20% of patients reported regret and disappointment at T2, which was more likely for those without a mutation of interest (MOI) detected vs those with a MOI detected (OR = 2.08, 95% CI, 1.13 to 3.83, p = 0.02). Conclusions: Web-based education prior to receipt of tumor genetic test results increases patient understanding of tumor genetic testing. While the intervention did not significantly reduce distress, results suggest that women who received the intervention had lower cancer-specific distress than those with usual care. Future refinements to the web-intervention are needed to address low literacy groups, men and patients with no actionable results. Clinical trial information: NCT02823652.

e19140 Background: HIV-infected (HIV+) breast cancer patients may have significantly worse survival compared to HIV-uninfected (HIV-). If so, identifying the underlying mechanism might lead to effective interventions to reduce the disparity. Relative dose intensity (RDI) < 0.85 has been associated with worse survival outcomes in non-metastatic breast cancer patients. We aimed to determine if RDI of chemotherapy and pathologic complete response (pCR) rates were lower for HIV+ patients who received neoadjuvant chemotherapy (NAC) compared with HIV-. Methods: We conducted a prospective cohort study in newly diagnosed breast cancer patients with locally advanced disease who initiated NAC at Princess Marina Hospital in Botswana between 2/2017 and 9/2019. Clinical and treatment data were collected at baseline and at every treatment visit. Surgical pathology post-NAC was graded as pCR if there was no invasive disease in the breast or lymph nodes. RDI was calculated for each patient, with optimal RDI ≥ 0.85. Dichotomous variables were compared using Fisher’s exact and chi-squared tests; and continuous variables using rank sum tests. Results: 111 patients were enrolled, of whom 84 (75.7%) were HIV-, 26 (23.4%) HIV+ and 1 (0.9%) with unknown status who was excluded from final analysis. HIV+ patients were less likely to receive optimal RDI (0.74 vs. 0.88; p = 0.03). Of the 110 patients 15 (13.6%) were still receiving chemotherapy; 22 (20%) prematurely discontinued chemotherapy of whom 11 (10%) received surgery; 7 (6.4%) completed chemotherapy but had no surgery. 77 (70%) completed surgery which included 11 (10%) with no pathology reports available, 3 (2.7%) inadequate surgical specimens and 63 (57.3%) complete pathology results included in pCR analysis: 1/13 (7.7%) HIV+ patients had a pCR compared to 12/50 (24%) in HIV-(p = 0.27). Conclusions: HIV+ patients were significantly more likely to receive inadequate neoadjuvant chemotherapy dose intensity, and trended towards a lower pCR in this small cohort, which may contribute to adverse treatment outcomes. Further study needed to validate high rate of treatment discontinuation and specific risk factors to inform targeted interventions to improve therapy delivery.

93 Background: Both routine PRO monitoring and specialty palliative care are associated with a survival benefit in advanced cancer patients, yet the integration of these efforts has not been described. As PRO collection becomes standard of care, there is a need to understand how PROs may be leveraged to identify patients who could benefit from palliative care referral. Methods: We applied latent profile analysis (LPA) to PROs from a national palliative care registry collected from 2008 – 2017 on 745 solid tumor patients at the time of initial outpatient palliative care visit. LPA is an established method to identify unobserved groups from variables of interest. We used patients’ responses to 11 questions across 4 palliative care domains (9 ESAS items and 2 items for social and existential distress) to generate “PRO profiles” and examined their clinical and demographic correlates using multinomial logistic regression. Results: Four PRO profiles were identified using 9 ESAS items (Table). Young age, metastatic disease, and tumor type (including breast, GYN, GI) differed across PRO profiles compared to lung. Patients with PPS < 70% were 4.5 times more likely to be in the High vs. Low symptom profile compared to those with PPS > 70%. Subgroup analyses showed correlation of social and existential distress PROs with Mood and High profiles. Conclusions: Cancer patients referred to outpatient palliative care can be differentiated into clinically meaningful PRO profiles using brief, routinely collected data in the real-world setting. PRO profiles provide richer data on patient needs compared to prognosis estimates or cancer stage, and synthesize big data for use in clinical practice and epidemiologic research. PRO profiles should include comprehensive palliative domains and be tested as screening thresholds for palliative care referral. [Table: see text]

1016 Background: The combination of CDK4/6 inhibitor (CDK4/6i) + endocrine therapy (ET) provides consistent improvement in PFS and response rates compared with single-agent ET as first- or subsequent-line therapy in HR+, HER2− advanced breast cancer (ABC), but the optimal regimen postCDK4/6i progression, including the role of continued CDK 4/6 blockade, is unclear. Methods: TRINITI-1 is a Phase I/II, open-label trial (NCT02732119) of triplet therapy: ribociclib (RIB; CDK4/6i) + everolimus (EVE; mTORi) + exemestane (EXE; ET) in men or postmenopausal women with HR+, HER2− ABC that progressed on prior CDK4/6i and up to 3 lines of therapy (≥ 1 ET and ≤ 1 chemotherapy regimen). Phase I determined RP2D; Phase II assessed efficacy/safety of RIB 300 or 200 mg + EVE 2.5 or 5 mg + EXE 25 mg/day. Here we present the first results in the entire patient population who received this triplet regimen and the correlation of biomarkers with outcomes. Results: As of October 24, 2018, 95 patients were evaluable (ET refractory and postCDK4/6i) in Phases I (n = 17) and II (n = 78). Continuous RIB + EVE + EXE demonstrated clinical benefit at week 24 in 39 patients (41.1%), exceeding the predefined primary end point threshold (> 10%). ORR was 8.4% by investigator assessment, median PFS was 5.7 months, and 1-year PFS was 33%. AEs were consistent with known safety profile of RIB, EVE, and EXE. Most common AEs were neutropenia (all grades, 41.7%; grade 3/4, 31.3%), stomatitis (41.7%; 3.1%), and fatigue (35.4%; 1.0%). No grade 3/4 QTc prolongation was noted. ctDNA genotyping revealed patients with certain tumor alterations, eg ESR1, had shorter median PFS vs wild-type: 3.5 vs 6.9 mo (HR 1.76, 95% CI 1.01–3.05). Additional genomic results, including PIK3CA, will be presented. Conclusions: TRINITI-1 met its primary efficacy end point and is the first trial to demonstrate clinical benefit and tolerability of continuous triplet therapy with ET + mTORi + CDK4/6i in patients with ET-refractory HR+, HER2− ABC postCDK4/6i progression. Tumor genomic profile might impact the clinical outcome with triplet therapy and warrants additional research to guide rational therapy selection. Clinical trial information: NCT02732119.

e23062 Background: PRO assessment has the potential to improve patient-provider communication, yet has been difficult to implement in practice. We developed and pilot-tested a web-based PRO assessment (Assessing Concerns at End of Treatment, ACE) within an existing cancer survivorship clinic to ascertain practicality, usability, and uptake by both patients and providers. Methods: ACE is a brief PRO assessment that interfaces with the patient-portal and delivers results into the electronic medical record (EMR). Prior to visit eligible patients were asked to complete a series of measures including a 19-item instrument assessing severity of physical and emotional difficulties and desire for assistance. These results were then made available to providers during the visit through the EMR. Patients were provided up to 3 reminder calls/emails to prompt completion. Eligibility included a breast cancer (BC) diagnosis up to 5 years prior to a scheduled survivorship visit, no current cancer treatment aside from hormonal therapies, and access to the internet. Results: Over 27-months 779 eligible BC survivors were approached and asked to participate, and 566 (73%) agreed. The ACE survey was completed by 332 (59%) of these patients prior to their visit. The most common difficulties reported were Fatigue (86.6%), Worry (75.4%), Difficulty Sleeping (74.8%), and Pain (72.2%). Patients most commonly requested assistance for Aching Joints (31.2%), Fatigue (29%), Difficulty Sleeping (28.6%), and Weight Gain (25.7%). Providers reported being burdened by the information provided and few referrals were made in response to ACE. Technical difficulties were encountered frequently and required more maintenance than initially anticipated. Conclusions: Most eligible patients agreed to complete ACE, however a minority actually did so despite repeated contacts. Lack of buy-in from providers was an obstacle, as were technical difficulties. Difficulties with physical and emotional issues were common, but desire for assistance was less so, and resulted in few referrals. Although practicable, questions remain about the cost vs. benefit of a web-based PRO assessment with survivors.

e18129 Background: Cancer drug stockouts occur at high frequencies globally, however their clinical effects are understudied in sub-Saharan Africa (SSA). We aim to describe prescription patterns and cost of systemic chemotherapy in cancer patients in Botswana during periods of stockout. Methods: Using a retrospective cohort study of the ten most common solid tumor malignancies treated with systemic chemotherapy at Princess Marina Hospital (PMH), Gaborone in 2016, we conducted a subset analysis of suboptimal events, defined as a cycle with ≥ 7 days delay or therapy switch from initiated guideline regimen, that occurred during drug stockout vs non-stockout periods. We estimated financial cost of therapy per cycle using Management Sciences for Health International Price Indicator Guide. Chi-squared and Wilcoxon rank sum were used for comparisons. Results: 167/378 patients contributed to 320 suboptimal events. 63% (201/320) of events occurred during a drug stockout, of which 43%, 43% and 14% were delays, switches, or both, respectively. There were significantly more delays (56% vs 44%, p < .0001) and switches (75% vs 26%, p < .0001) during stockout periods vs no stockout. The majority of switches during drug stockouts occurred in breast cancer patients receiving curative therapy: 48% (20/42) were “paclitaxel + trastuzumab” ($4673) to “paclitaxel alone” ($35) in HER2 positive patients resulting in a 99% cost decrease; and 29% (12/42) were paclitaxel ($35) to docetaxel ($108) resulting in a 209% cost increase per cycle switched. Colon cancer patients receiving palliative-intent therapy were the second most frequent patients with therapy switches during stockout periods: 42% (8/19) were “capecitabine + oxaliplatin” ($259) to “capecitabine alone” ($105) resulting in a 59% cost decrease. Conclusions: Breast cancer patients form the majority of patients treated with systemic chemotherapy at PMH and experienced the most delays and switches in therapy during drug stockout periods. Changes in drug prescription patterns during stockout periods may be associated with switches leading to inferior but less costly regimens, and in some cases costly regimens with higher toxicity. Interventions that minimize cancer drug stockouts are imperative and further studies to understand impact of stockout on survival are needed in SSA.