Scalp cooling is standard-of-care for prevention of chemotherapy-induced alopecia (CIA), with proven safety and efficacy. Limb cryotherapy has shown promise in preventing chemotherapy-induced peripheral neuropathy (CIPN). The safe application of concomitant scalp and limb cryotherapies during chemotherapy is crucial due to concerns about potential interactions, including central hypothermia, yet limited data exist on their safe delivery in this context. Here we report a prospective, single-arm study assessing feasibility, safety, and tolerability of concomitant scalp cooling and limb cryocompression in healthy volunteers, and in cancer patients undergoing chemotherapy. Safety and tolerability of concomitant scalp cooling and limb cryocompression were evaluated in healthy volunteers and then in cancer patients receiving weekly paclitaxel chemotherapy. Limb cryocompression was administered starting at 11 °C, with thermoregulation allowed up to 25 °C to accommodate patient tolerance. Core body temperature changes, adverse events (CTCAE v4.0), and tolerance to cryotherapy were documented. EORTC Quality of Life Questionnaire-CIPN20 scores were evaluated before the start of chemotherapy (QoLpre), after the last cycle of chemotherapy (QoLpost), and 3 months after the last cycle of chemotherapy (QoL3m). Physician grading of CIA was documented using CTCAE v4.0, and results at baseline and at completion of weekly paclitaxel were compared. Concomitant scalp and limb cryocompression at 11 °C was safe and tolerable in healthy volunteers (n = 3). Fifteen patients enrolled in the study and 13 completed the entire treatment, with negligible core body temperature changes (− 0.18 °C ± 0.37). Eight patients completed all 12 cycles of cryocompression at 11 °C while some required thermoregulation (range 14 °C to 18 °C). One patient completed all cryotherapy cycles at 25 °C and another withdrew due to intolerance to 25 °C. There were no occurrences of ≥ Grade 2 neuropathy. QoL was preserved and scores remained stable at QoL3m (18 (18–21); median (IQR)) compared to QoLpre (18 (18–19)). Patients who underwent cryocompression at lower temperatures showed better preservation of QoL scores (QoL3m 18 (18–20)) than the others (QoL3m 26 (22–31)). 11/13 patients (85

Abstract Background: ER+ breast cancer is the most common subtype of breast cancer. Although most patients respond initially to endocrine therapy (ET), endocrine resistance inevitably develops, leading to disease progression. Lenvatinib, a multi-kinase inhibitor, demonstrated clinical benefit in the treatment of patients with advanced ER+ breast cancer who have progressed on ET in a phase Ib/II clinical trial from our group. Our study aims to elucidate the molecular mechanism of action of lenvatinib in ER+ breast cancer. Methods: A cell viability assay was performed to assess the sensitivity of four ER+ cell lines to lenvatinib. Western blot was used to elucidate its effect on downstream pathway signalling, and cell cycle arrest investigated through flow cytometry. A series of functional assays, including BrdU, colony formation and wound-healing assays assessed proliferative, clonogenic and migratory activity respectively. The effect of lenvatinib on epithelial-mesenchymal transition (EMT) was analysed using RT-qPCR, and compared with siRNA knockdown (KD) of Fgfr1 and Fgfr2. Results: ER+ cell lines demonstrated sensitivity to lenvatinib in the micromolar range. Western blot showed downregulation of FGFR1, FGFR2, pERK and pAKT expression post-treatment. Lenvatinib was found to induce a G1 phase arrest, suppressed cell proliferation in a dose-dependent manner, and diminished both the clonogenic ability and migratory activity of ER+ cells. Lenvatinib treatment reduced expression of Fgfr1, Fgfr2 and the mesenchymal markers N-cad and Fibronectin, while increasing the expression of the epithelial markers E-cad and Claudin-1, indicating potential inhibition of EMT. A similar change in EMT marker expression was observed in Fgfr1 KD but not Fgfr2 KD cells. Conclusion: Lenvatinib demonstrated potent anti-cancer activity and induction of G1 phase arrest, leading to decreased cell proliferation, reduction of clonogenic ability and cell migration. EMT inhibition was also observed, possibly through the FGFR1 signalling pathway. Citation Format: Natasha Gandasasmita, Gauri Vaidya, Arpita Datta, Charlie Marvalim, Joline Si Jing Lim, Soo Chin Lee. Elucidating the Mechanism of Action of Lenvatinib in Estrogen Receptor-Positive (ER+) Breast Cancer [abstract]. In: Proceedings of Frontiers in Cancer Science; 2023 Nov 6-8; Singapore. Philadelphia (PA): AACR; Cancer Res 2024;84(8_Suppl):Abstract nr P24.

43 Background: The role of IRAK1 pathway in inflammatory and immune response is established in autoimmune diseases but less well-understood in cancer. Chromosome 1q21.3 CNA detected in plasma cell-free DNA was observed in pts with advanced solid tumors, and associated with IRAK1 upregulation. In preclinical animal models, IRAK1 upregulation promoted tumorigenesis, while its inhibition led to decreased tumor growth. Pacritinib is a JAK2/FLT3 inhibitor that is FDA approved for treatment in myelofibrosis, but also have known activity against IRAK1. We hypothesize that pacritinib may be effective in disease control of pts with plasma 1q21.3 CNA. Methods: A phase Ib/II clinical trial was designed to investigate the efficacy of pacritinib in pts with treatment (rx) refractory solid tumors harboring 1q21.3 CNA. Serial pt tumor and blood samples were collected and analyzed to elucidate the effect of IRAK1 inhibition on tumor microenvironment and systemic immune modulation. Results: 330 patients were screened, 1q21.3 CNA was detected in 30.1% of pts. Highest incidence of 1q21.3 CNA positivity was detected in breast cancer (39.8%), colorectal cancer (39.7%) and lung cancer (36.1%). 12 pts were commenced on rx over 3 dose levels (DL) (DL1: n=6, DL2: n=3, DL3: n=3). At DL1 (200mg BID), no DLTs were observed, but 2 pts had G3 transaminitis attributed to drug/disease, and 1 pt had intolerable G2 rash; decision was made for dose reduction. At DL2 (200mg OM, 100mg ON), no DLTs were observed. Reescalation to 200mg BID (DL3) was carried out with no DLT observed. Pacritinib at 200mg BD was declared the recommended phase II dose in pts with solid tumors. In the dose expansion cohort, 8 pts (4 colorectal cancer, 3 hepatobiliary [HPB] cancer, 1 lung cancer) have been enrolled thus far. No objective responses were observed. Within pts with HPB tumors, 1 pt with pancreatic cancer had a progression-free survival (PFS) of 25.0 weeks, and 1 pt with cholangiocarcinoma had a PFS of 15.9 weeks. Preliminary analysis of serial tumor biopsy samples suggest an expansion of CD8+ T cell population with pacritinib rx. Serial peripheral blood mononuclear cells analysis showed no significant trend in change in CD8+ T cell population, but a predominance of PD-1+ T cells with rx, and also an increase in CD4+ T cell population. In the myeloid cell population, there appears to be decrease in dendritic cell population, but no significant change in trend of macrophage was observed. Conclusions: Pacritinib at 200mg BID is safe and tolerable in pts with solid tumors. IRAK1 inhibition appears to modulate immune cell populations both in the tumor microenvironment and systemic circulation. Dose expansion is underway, with potential signal of disease control in HPB tumors. Clinical trial information: NCT04520269 .

e14507 Background: ADG106 is a fully human agonistic anti-CD137 IgG4 monoclonal antibody which modulates the tumor microenvironment and has demonstrated increased efficacy when added to chemotherapy in preclinical models. We studied the combination of ADG106 with chemotherapy. Methods: We conducted a phase Ib trial in patients with advanced solid tumors to determine the recommended phase 2 dose (RP2D) of ADG106 + weekly P (paclitaxel 80mg/m 2 ) or ddAC (doxorubicin 60mg/m 2 , cyclophosphamide 600mg/m 2 Q2W with pegfilgrastim), followed by a phase II trial of neoadjuvant ADG106 + weekly Px12→ADG106 + ddACx4→surgery in stage I-III HER2 negative breast cancer patients. In phase Ib, one dose of single agent ADG106 was administered followed 2 weeks later by ADG106 + ddAC (Cohort 1) or ADG106 + weekly P (Cohort 2). Dose levels (DL) of ADG106 were 50mg (DL-1), 100mg (DL1), 200mg (DL2). Serial tumor biopsies were performed at baseline, after single agent ADG106 and at disease progression in phase I, and at baseline, after single agent ADG106, after cycle 1 ADG106 + P, and at surgery in phase II for translational studies. Results: 11 patients were enrolled into Phase Ib with median 3 (range 2-11) prior lines of palliative systemic therapy. ADG106 + ddAC (n=2 at DL1) was deemed intolerable with 1 patient experiencing G4 neutropenia and the other G3 infection; thus ADG106 was not added to ddAC in phase II. No DLTs were observed in all patients receiving ADG106 + P (n=6 at DL1; n=3 at DL2); ADG106 RP2D was declared at 200mg + P. In this cohort, the most common all-grade AEs were neutropenia (n=6), peripheral neuropathy (n=6) and fatigue (n=6); significant ≥G3 AEs were infection (n=2) and G3 neutropenia (n=6). 5/11 (45%) patients in phase I achieved clinical benefit (CBR; PR=2, SD=3) which is clinically meaningful as 9/11 (82%) had prior taxane exposure. 18 of the planned 30 patients have been enrolled into Phase II (ADG106+weekly P→ddACx4→surgery); 10 have completed study treatment and 5 have undergone surgery. While on ADG106 + P, 4 patients experienced G3 adverse events (AEs): neutropenia (n=3), hypophosphatemia (n=1), fever (n=1). Most common G1-2 AEs were ALT elevation (n=4), acneiform rash (n=3) and peripheral neuropathy (n=3). While on ddAC alone, all AEs were low grade except for 1 patient who had G3 pneumonitis from Pneumocystis Jiroveci Pneumonia. 26 sets of matched tumor biopsies have been collected (9 in phase I; 17 in phase II) and will be tested for a panel of 40 markers by multiplex IHC, including CD137, PD-L1, and CD3/4/8. Conclusions: ADG106 when combined with ddAC exacerbates neutropenia and is not tolerable despite prophylactic pegfilgrastim. The RP2D of ADG106 in combination with P is 200mg and is safe and tolerable; manageable G3 neutropenia was the most common AE. There are no new safety signals thus far in Phase II. Further efficacy analyses and studies on tumor immune markers are ongoing. Clinical trial information: NCT05275777 .

PURPOSE:Human epidermal growth factor receptor 2 (HER2)-targeted therapy is standard of care for HER2-positive (HER2+) breast cancer, but most patients develop progressive disease with persistent HER2 expression. No definitive treatment guidance currently exists beyond second line. Trastuzumab duocarmazine (T-Duo) is a third-generation, HER2-targeted antibody-drug conjugate that demonstrated efficacy and acceptable safety in phase I studies of heavily pretreated patients with HER2+/HER2-low breast cancer. METHODS:In this open-label, randomized, phase III trial, T-Duo was compared with physician's choice (PC) in patients with unresectable locally advanced/metastatic HER2+ breast cancer with progression during/after ≥2 HER2-targeted therapies or after trastuzumab emtansine (T-DM1). The primary endpoint was progression-free survival (PFS) by blinded independent central review. RESULTS:In total, 437 patients were randomly assigned 2:1 to T-Duo (n = 291) or PC (n = 146). The median age was 56.0 years (range, 24-86); most patients (93.6%) had metastatic disease. The median time from diagnosis of metastatic disease to trial entry was 3.5 years; the median number of prior HER2-targeted therapies in metastatic setting was three. The median PFS was 7.0 months (95% CI, 5.4 to 7.2) with T-Duo versus 4.9 months (95% CI, 4.0 to 5.5; hazard ratio [HR], 0.64 [95% CI, 0.49 to 0.84]; P = .002) with PC. PFS benefit was maintained across most predefined subgroups. The median overall survival (first analysis) was 20.4 (T-Duo) versus 16.3 months (PC; HR, 0.83 [95% CI, 0.62 to 1.09]; P = .153). Objective response rate was 27.8% (T-Duo) versus 29.5% (PC); other efficacy end points-clinical benefit rate, duration of response, and reduction in target lesion measurement-tended to favor T-Duo. Grade ≥3 treatment-emergent adverse events occurred in 52.8% (T-Duo) versus 48.2% (PC). CONCLUSION:Treatment with T-Duo was manageable, but tolerability was affected by prevalent ocular toxicity, leading to a higher discontinuation rate in the T-Duo arm. T-Duo significantly reduced the risk of progression in patients with advanced HER2+ breast cancer who have progressed during/after ≥2 HER2-targeted therapies or after T-DM1.

Purpose Scalp cooling therapy (SCT) improves chemotherapy induced alopecia (CIA), but there are few published data about its efficacy in an Asian-predominant population. We report our tertiary institution experience of SCT in patients with breast or gynaecological cancers undergoing chemotherapy. Methods The Paxman scalp cooling system was employed for eligible women with breast or gynaecological cancers receiving anthracycline or taxane based chemotherapy. Only patients with Grade (G) 0–1 alopecia by common terminology criteria for adverse events (CTCAE) version 4.0 were eligible initially, but patients with G2 alopecia were later included in the study. SCT was performed at each chemotherapy cycle, commencing 30 minutes prior to and continuing up to 90 minutes after completion of the drug infusion. Patients were assessed at the start and end of each session for hair preservation (defined as G0–2 alopecia) and comfort level of SCT (rated on a 5-point visual scale). The primary end point was success of hair preservation or hair regrowth after completion of all cycles of chemotherapy. Results 83 participants were enrolled over a period of 18 months from December 2017 to October 2019, with a total of 510 scalp cooling cycles performed. 94.0% (n = 78) of patients reported a comfort score of 3 (indicating that procedure was comfortable) and above upon a 5-point visual scale. Patients receiving weekly paclitaxel had highest success in hair preservation at 76.7% (23/30 patients), with a lower rate of hair preservation observed for the 3-weekly paclitaxel regimen (50%, 2/4 patients). In contrast, only 1 patient (5.3%, 1/19 patients) who underwent chemotherapy with anthracycline and cyclophosphamide achieved hair preservation. Conclusion SCT is well tolerated in an Asian predominant population. Among women with breast or gynaecological cancers in Singapore receiving taxane and/or anthracycline based chemotherapy, those who underwent SCT were about 50% more likely to achieve hair preservation or hair regrowth, as compared to historical controls.

IMPORTANCE Despite patients with cancer being at risk of poor outcomes from COVID-19, there are few published studies for vaccine efficacy in this group, with suboptimal immunogenicity and waning vaccine efficacy described in small studies being a concern. OBJECTIVE To assess the incidence rate of severe COVID-19 disease outcomes associated with the number of vaccine doses received and the waning of protection over time. DESIGN, SETTING, AND PARTICIPANTS A prospective multicenter observational cohort study was carried out over 2 time periods (September 15, 2021, to December 20, 2021 [delta wave], and January 20, 2022, to November 11, 2022 [omicron wave]) predominated by SARS-CoV-2 delta and omicron variants, respectively. Overall, 73 608 patients with cancer (23 217 active treatment, 50 391 cancer survivors) and 621 475 controls matched by age, sex, race and ethnicity, and socioeconomic status were included. EXPOSURE Vaccine doses received, from zero to 4 doses, and time elapsed since last vaccine dose. OUTCOMES Competing-risk regression analyses were employed to account for competing risks of death in patients with cancer. Main outcomes were incidence rate ratios (IRRs) of COVID-19 infection, hospitalization, and severe disease (defined as requirement for supplemental oxygen, intensive care, or death). The IRRs stratified by time from last vaccine dose served as indicators of waning of vaccine effectiveness over time. RESULTS The mean (SD) age of actively treated patients with cancer, cancer survivors, and controls were 62.7 (14.7), 62.9 (12.6), and 61.8 (14.7) years, respectively. Of 73 608 patients with cancer, 27 170 (36.9%) were men; 60 100 (81.6%) were Chinese, 7432 (10.1%) Malay, 4597 (6.2%) Indian, and 1479 (2.0%) were of other races and ethnicities. The IRRs for the 3-dose and 4-dose vs the 2-dose group (reference) for COVID-19 hospitalization and severe disease were significantly lower during both the delta and omicron waves in cancer and control populations. The IRRs for severe disease in the 3-dose group for active treatment, cancer survivors, and controls were 0.14, 0.13, and 0.07 during the delta wave and 0.29, 0.19, and 0.21 during omicron wave, respectively. The IRRs for severe disease in the 4-dose group during the omicron wave were even lower at 0.13, 0.10 and 0.10, respectively. No waning of vaccine effectiveness against hospitalization and severe disease was seen beyond 5 months after a third dose, nor up to 5 months (the end of this study's follow-up) after a fourth dose. CONCLUSION This cohort study provides evidence of the clinical effectiveness of mRNA-based vaccines against COVID-19 in patients with cancer. Longevity of immunity in preventing severe COVID-19 outcomes in actively treated patients with cancer, cancer survivors, and matched controls was observed at least 5 months after the third or fourth dose.

1099 Background: Fluoropyrimidines are commonly used in the treatment of patients (pts) with metastatic breast cancers (MBC). FTD/TPI is an oral drug combination of trifluridine with tipiracil, a thymidine phosphorylase inhibitor preventing rapid degradation of trifluridine, thus allowing for increased exposure to active agent, and has showed activity in pts with colorectal and gastric cancers despite prior exposure to fluoropyrimidines. We investigate the role of FTD/TPI in MBC pts with (Cohort A) or without (Cohort B) prior exposure to fluoropyridines in a single arm phase II study. Methods: Pts were treated with FTD/TPI, and enrolled first into a lead-in dose confirmation phase, followed by two parallel cohorts based on prior exposure to fluoropyrimidines. Primary objectives for each cohort included determination of progression-free survivals (PFS), and secondary objectives included determination of objective response rates (ORR), safety and tolerability. Results: A total of 74 pts were recruited (42 for Cohort A, 32 for Cohort B), of whom 4 belonged to lead-in phase. Dosing was confirmed at FTD/TPI 35mg/m 2 days 1-5 and 8-12 of 4-weekly cycles based on lead-in phase with no dose-limiting toxicities observed, and recruitment then proceeded in 2 parallel cohorts. All pts were evaluable for toxicity and survival analyses, and 72 were evaluable for ORR. Median age at enrolment was 62 years (range 32-85), with median of 4 (range 0-14) prior lines therapy in the metastatic setting, and 47% had de novo metastatic disease. Median PFS was 5.7 months (95% CI 3.8 to 8.3) and 9.4 months (95% CI 5.5 to 14.0) respectively in Cohorts A and B. Similar response rates were observed regardless of prior exposure to fluoropyrimidine, with ORR of 19.5% (95% CI 8.8 to 34.9) and 16.1% (95% CI 5.5 to 33.7) in Cohorts A and B, with 6-month clinical benefit rates of 56.1% (95% CI 39.7 to 71.5) and 61.3% (95% CI 42.2 to 78.2) respectively. Safety profile was consistent with known toxicities of FTD/TPI, with most common treatment-related adverse events of neutropenia, fatigue, nausea and anorexia. 64% of pts required dose modifications during study treatment, most commonly due to neutropenia, that could be overcome by dose reduction or prolongation from 4- to 5-weekly cycles. Only 1 pt required discontinuation due to toxicity from therapy. Conclusions: FTD/TPI showed promising anti-tumor activity with meaningful clinical benefit even among pts with prior exposure to fluoropyrimidines, and has a reasonable toxicity profile with appropriate dose modification. An oral chemotherapy option with good disease control provides an attractive treatment alternative to pts with MBC where quality of life is paramount, warranting further investigation in randomised studies. Clinical trial information: NCT04280536 .

1096 Background: Oral SERDs are a novel drug class developed to counteract endocrine resistance due to ESR1 mutations. Several SERDs have emerged from phase 2 and 3 trials, and the FDA has most recently limited approval for Elacestrant to patients with ESR1mt tumours despite PFS benefit in the overall population. Questions remain on whether patients with ESR1wt tumours stand to benefit from SERDs. We conducted an IPD meta-analysis of the trials EMERALD, SERENA2, ACELERA and AMEERA3 to compare survival outcomes of SERDs in the 2nd or 3rd line setting against endocrine therapy (ET), using KMSubtraction to unveil HRs of unreported ESR1wt subgroups from AMEERA3 and EMERALD. Meta-analysis results were stratified by ESR1 status. Methods: RCTs investigating the efficacy of novel SERDs versus ET for ER+, HER2- MBC, and which reported the Kaplan Meier (KM) plots of progression free survival (PFS) were selected after a systematic search of Embase and PubMed from inception until January 21,2023. A graphical reconstructive algorithm was applied to estimate time-to-event outcomes from reported KM plots in all overall and reported subgroup cohorts, deriving IPD. A bipartite matching algorithm, KMSubtraction was used to subtract patients in the reported subgroup from the overall cohort, to derive survival data for unreported ESR1wt subgroups. An IPD meta-analysis was then performed, pooling data by ESR1 mutation. Results: A total of 1216 patients were included in this analysis. In the pooled analysis of the overall cohort, PFS benefit was observed with SERDs compared to treatment of physician's choice (TPC) (HR 0.787, 95%CI 0.683-0.908, p<0.001). In the ESR1mt subgroup SERDs demonstrated improved PFS (HR 0.557, 95%CI 0.440-0.705, p<0.001) compared with TPC. In the ESR1wt subgroup, SERDs demonstrated no significant PFS benefit (HR 0.948, 95%CI 0.790-1.137, p=0.565) when compared to TPC. KMSubtraction was implemented on AMEERA3 to reveal survival data in ESR1wt subgroup. Amcenestrant revealed no significant PFS difference in the ESR1wt population (HR 1.197, 95% CI 0.857-1.670, p=0.291) when compared to ET. Additionally, a separate analysis of EMERALD was performed using KMSubtraction to derive survival data of the ESR1wt subgroup comparing Elacestrant vs Fulvestrant. No significant PFS difference was observed between the 2 agents in the ESR1wt population (HR 0.832, 95% CI 0.587-1.178, p=0.299). Conclusions: Our results suggest that PFS benefit in the overall population is mainly driven by the ESR1mt subgroup. These findings are in line with the recent FDA approval of Elacestrant for patients with ESR1mt tumours. [Table: see text]

Background: Oestrogen receptor positive, human epidermal growth factor receptor-2 (HER2) negative breast cancer (BC) is the most frequently diagnosed BC subtype. Combinations of cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) with anti-oestrogen therapy have led to improved survival compared with anti-oestrogen therapy alone for advanced/metastatic BC. The evaluation of CDK4/6i in the real-world facilitates treatment planning, insights into the incidence of drug toxicities, dose modifications including dose delays (DDs) and dose reductions (DRs) and improves prognostic accuracy in subgroups, for example geriatric patients, who are under-represented in clinical trials. Methods: This multi-centre study analysed retrospective and prospective data from 456 patients treated with CDK4/6i between January 2015 and December 2020. We examined patient characteristics, variation in prescribing practices, efficacy and toxicity outcomes. Results: In all, 456 patients were included in this study. The median age was 59 (range: 24–92). In total, 85 (19%) were ⩾70 years old. In all, 122 (27%) and 119 (26%) of patients were treated in the first-line and second-line settings, respectively. In total, 25 (5%), 31 (7%) and 145 (32%) of patients had brain, peritoneum and liver metastasis, respectively, at the time of CDK4/6i initiation. On univariate analysis, heavily pre-treated patients and those with distant metastases, involving the liver, brain or peritoneum, had significantly shorter progression-free survival (PFS) and 24-month overall survival (OS). Elderly patients (⩾70) had a shorter PFS; OS results were not mature. Majority of patients ( n = 362, 80%) initiated treatment with the United States FDA-approved starting dose of CDK4/6i. In all, 330 (72%) had at least one DD and 217 (48%) patients required at least one DR, but these dose modifications were not associated with poorer survival outcomes. Patients age ⩾70 were more likely to require dose modifications leading to a lower treatment dose. The most common reason for DD/DR was neutropenia (60%) and the incidence of febrile neutropenia was only 2%. Conclusions: Our study indicates CDK4/6i is effective and safe. Age ⩾ 70, distant metastases to liver, peritoneal or brain were negative prognostic factors. Age ⩾ 70 was associated with significantly increased requirement for dose modification; however, this did not impact survival outcomes. These findings provide reassurance that survival outcomes are not adversely affected in elderly patients when DD/DR is indicated.

Purpose Tumor angiogenesis controlled predominantly by vascular endothelial growth factor and its receptor (VEGF-VEGFR) interaction plays a key role in the growth and propagation of cancer cells. However, the newly formed network of blood vessels is disorganized and leaky. Pre-treatment with anti-angiogenic agents can “normalize” the tumor vasculature allowing effective intra-tumoral delivery of standard chemotherapy. Immunohistochemistry (IHC) analysis was applied to investigate and compare the vascular normalization and anti-angiogenic effects of two commonly used anti-angiogenic agents, Sunitinib and Bevacizumab, administered prior to chemotherapy in HER2-negative breast cancer patients. Methods This prospective clinical trial enrolled 38 patients into a sunitinib cohort and 24 into a bevacizumab cohort. All received 4 cycles of doxorubicin/cyclophosphamide chemotherapy and pre-treatment with either sunitinib or bevacizumab. Tumor biopsies were obtained at baseline, after cycle 1 (C1) and cycle 4 (C4) of chemotherapy. IHC was performed to assess the tumor vascular normalization index (VNI), lymphatic vessel density (LVD), Ki67 proliferation index and expression of tumor VEGFR2. Results In comparison to Bevacizumab, Sunitinib led to a significant increase in VNI post-C1 and C4 ( p < 0.001 and 0.001) along with decrease in LVD post-C1 ( p = 0.017). Both drugs when combined with chemotherapy resulted in significant decline in tumor proliferation after C1 and C4 (baseline vs post-C4 Ki67 index p = 0.006 for Sunitinib vs p = 0.021 for Bevacizumab). Bevacizumab resulted in a significant decrease in VEGFR2 expression post-C1 ( p = 0.004). Conclusion Sunitinib, in comparison to Bevacizumab showed a greater effect on tumor vessel modulation and lymphangiogenesis suggesting that its administration prior to chemotherapy might result in improved drug delivery. Trial registry ClinicalTrials.gov: NCT02790580 (first posted June 6, 2016).

[vic-]Trastuzumab duocarmazine (SYD985, Byondis B.V., NL) is a novel HER2-targeting antibody–drug conjugate comprised of trastuzumab bound to a linker drug containing duocarmycin. TULIP assessed the efficacy of SYD985 in advanced HER2-positive breast cancer.

1019 Background: Preclinical studies show cross talk between RET and estrogen receptor, with at least additive treatment (Tx) effect of Len, a RET inhibitor, with Let. Our previous work concluded a recommended phase 2 dose (RP2D) of Len 14mg daily and Let 2.5mg daily (Lim, ASCO 2019). We present efficacy data from dose escalation and expansion cohorts. Methods: Safety, tolerability and efficacy data of MBC patients in both dose escalation (Len dose level 1 [DL]:20mg, DL -1:16mg and DL -2:14mg) and expansion (Len 14mg) cohort of this phase Ib/II study of combination Len+Let study was analysed. Patients were treated with single-agent Len for 2 weeks, followed by Len+Let until disease progression (PD). Serial tumor biopsies at baseline, after Len alone, 4 weeks post Len+Let, and upon PD, were sequenced for 440 genes with the ACTOnco+ platform. Results: A total of 33 pts (DL1 6pts, DL-1 6pts, DL-2 + expansion 21pts) with median 5 lines of prior Tx (range 0-11) were enrolled; 87.9%, 75.8%, and 75.8% had prior endocrine therapy (ET), ET+CDK4/6 inhibitor (i), and chemotherapy (CT) respectively. Objective response rate (ORR), disease control rate (DCR) ≥6 months (m), median duration of response (DOR), and percentage progression-free (PPF) at 12m were 33.3%, 45.5%, 11.5m (range 6.3-22.4), and 27.2% respectively. Among patients who previously progressed on CDK4/6i (n = 25), ORR, DCR ≥6m, median DOR, and PPF at 12m were 24.0%, 40.0%, 13.7m (range 6.3-18.2), and 12.0% respectively. Of note, 3/25 (12%) patients had durable response to Len+Let lasting ≥12m, despite having only modest PFS on ET+CDK4/6i (3, 7, and 12 months respectively). Most frequent all-grade toxicities (tox) were HTN (n = 15, G3:15), hypothyroidism (n = 20, G3:0) and fatigue (n = 13, G3:2), with no G4/5 tox. No new toxicity signals were observed compared to dose escalation phase. Pre-treatment tumor molecular profiling showed responders to be more likely to harbor NEFH, USH2A and PTCH1 mutations, while non-responders were more likely to carry PIK3R1, APC and PALB2 mutations. Sequencing of serial biopsies showed downregulation of BRD4, PTCH1, KIT, NTRK1 and CREBBP after Len treatment. Conclusions: Len+Let showed significant anti-tumor activity with meaningful duration of response, even in pts who failed prior CT or ET+CDK4/6i. The results support further investigation in randomized studies. Tumor profiling identified mutations associated with response and insights on molecular effects of lenvatinib. Clinical trial information: NCT02562118 .

Purpose Severe peripheral neuropathy is a common dose-limiting toxicity of taxane chemotherapy, with no effective treatment. Frozen gloves have shown to reduce the severity of neuropathy in several studies but comes with the incidence of undesired side effects such as cold intolerance and frostbite in extreme cases. A device with thermoregulatory features which can safely deliver tolerable amounts of cooling while ensuring efficacy is required to overcome the deficiencies of frozen gloves. The role of continuous-flow cooling in prevention of neurotoxicity caused by paclitaxel has been previously described. This study hypothesized that cryocompression (addition of dynamic pressure to cooling) may allow for delivery of lower temperatures with similar tolerance and potentially improve efficacy. Method A proof-of-concept study was conducted in cancer patients receiving taxane chemotherapy. Each subject underwent four-limb cryocompression with each chemotherapy infusion (three hours) for a maximum of 12 cycles. Cryocompression was administered at 16 °C and cyclic pressure (5–15 mmHg). Skin surface temperature and tolerance scores were recorded. Neuropathy was assessed using clinician-graded peripheral sensory neuropathy scores, total neuropathy score (TNS) and nerve conduction studies (NCS) conducted before (NCS pre ), after completion (NCS post ) and 3 months post-chemotherapy (NCS 3m ). Results were retrospectively compared with patients who underwent paclitaxel chemotherapy along with continuous-flow cooling and controls with no hypothermia. Results In total, 13 patients underwent 142 cycles of cryocompression concomitant with chemotherapy. Limb hypothermia was well tolerated, and only 1 out of 13 patients required an intra-cycle temperature increase, with no early termination of cryocompression in any subject. Mean skin temperature reduction of 3.8 ± 1.7 °C was achieved. Cryocompression demonstrated significantly greater skin temperature reductions compared to continuous-flow cooling and control ( p < 0.0001). None of the patients experienced severe neuropathy (clinician-assessed neuropathy scores of grade 2 or higher). NCS analysis showed preservation of motor amplitudes at NCS 3m in subjects who underwent cryocompression, compared to the controls who showed significant deterioration (NCS 3m cryocompression vs. NCS 3m control: ankle stimulation: 8.1 ± 21.4%, p = 0.004; below fibula head stimulation: 12.7 ± 25.6%, p = 0.0008; above fibula head stimulation: 9.4 ± 24.3%, p = 0.002). Cryocompression did not significantly affect taxane-induced changes in sensory nerve amplitudes. Conclusion When compared to continuous-flow cooling, cryocompression permitted delivery of lower temperatures with similar tolerability. The lower skin surface temperatures achieved potentially lead to improved efficacy in neurotoxicity amelioration. Larger studies investigating cryocompression are required to validate these findings.

The ensuing COVID-19 pandemic poses unprecedented and daunting challenges to the routine delivery of oncological and supportive care to patients with breast cancer. Considerations include the infective risk of patients who are inherently immunosuppressed from their malignancy and therapies, long-term oncological outcomes from the treatment decisions undertaken during this extraordinary period, and diverted healthcare resources to support a coordinated whole-of-society outbreak response. In this review, we chronicle the repercussions of the COVID-19 outbreak on breast cancer management in Singapore and describe our approach to triaging and prioritising care of breast tumours. We further propose adaptations to established clinical processes and practices across the different specialties involved in breast oncology, with references to the relevant evidence base or expert consensus guidelines. These recommendations have been developed within the unique context of Singapore's public healthcare sector. They can serve as a resource to guide breast cancer management for future contingencies in this city-state, while certain elements therein may be extrapolatable to other medical systems during this global public health emergency.

e12511 Background: A central mechanism for the anti-tumor activity of Trastuzumab, a HER2 monoclonal antibody, against HER2+ tumors is induction of antibody dependent cell cytotoxicity (ADCC) mediated by NK cells. We are conducting a first-in-human trial of Trastuzumab followed by infusion of expanded, activated autologous NK cells in refractory HER2+ MBC (ClinicalTrials.gov: NCT02030561) to test the hypothesis that NK cell infusions will augment Trastuzumab-mediated ADCC and increase immune cell infiltration in tumor. Pre- and post-infusion tumor biopsies were obtained in a subset of patients to determine degree of NK cell infiltration in tumor and histopathological and immunological effects after infusion. Methods: HER2+ MBC patients underwent apheresis to harvest NK cells for ex vivo expansion and activation. NK cells (107/kg), expressing high levels of the antibody receptor CD16, were infused 24 hours post-Trastuzumab. Histology analysis and immunohistochemistry with CD56, CD3, CD20 and cleaved caspase-3 to identify NK, T, B, and apoptotic cells respectively, was performed in pre- and post-infusion biopsies. Studies of CD4 and CD8 to further classify T cell infiltrates, and CD16 to assess NK cell functionality are underway. Results: Analysis of 7 paired tumor biopsies collected before and 7-14 days after NK cell infusion showed absolute increase in lymphocyte infiltration (mean cell count/5 HPF: 204 vs 265 in pre- vs post- biopsy, p = 0.109). Most infiltrating lymphocytes were CD3+ T cells (74.28±12.72% vs 80 ±10% in pre vs post) and CD56+ NK cell number in the immune infiltrate were increased post infusion (mean cell count/5 HPF: 4.57±3.46 vs 20.57±13.83 in pre vs post; p = 0.009). Increased tumor apoptosis was observed post NK cell infusion (mean apoptotic cell count/5 HPF: 3.14±2.48 vs 5.86±6.72 in pre vs post, p = 0.27). Conclusions: Histopathology analysis of tumors from HER2+ MBC patients demonstrated significant increase in NK and T cells in tumor following Trastuzumab and NK cell infusion, suggesting that this combination might also augment recruitment of T lymphocytes into tumor, further enhancing anti-tumor activity. Clinical trial information: NCT02030561.

1045 Background: Endocrine blockade (EB) is standard of care for patients (pts) with HR+ LABC/MBC. RET over-expression (RET+) occurs in up to 75% of HR+ breast cancers and is a postulated mechanism of endocrine resistance. Preclinical studies show cross talk between RET and estrogen receptor, and at least additive treatment (Tx) effect of Len+EB. Methods: We performed a phase Ib trial (3+3 dose escalation) to study safety, tolerability, pharmacodynamics and efficacy of Len+Let. Both drugs were given as continuous daily dosing with 2 weeks (wks) of Len alone, followed by Len+Let for 12 wks then surgery (LABC), or till disease progression (PD) (MBC). Serial tumor biopsies (n = 15) were done at baseline, after Len alone, 4 wks post Len+Let, and at surgery [LABC] / upon PD [MBC]. Results: 16 pts were treated (4 LABC, 12 MBC); Among MBC pts, median lines of prior Tx was 3 (range 0-10); 84.6%, 66.7%, and 58.3% had prior EB, EB+CDK4/6 inhibitor (i), and chemotherapy (CT) respectively. At dose level (DL) 1, 2/4 pts had dose-limiting toxicities (DLT). There was no DLT at DL-1, but 6/6 pts needed dose reductions (DR), with 4/6 DR within 6 wks of Len+Let (3 G3 hypertension [HTN], 1 G3 wound pain), deeming DL-1 intolerable. At DL-2, 0/6 pts had DLT; this was declared recommended phase 2 dose (RP2D). Most frequent G3 toxicities (tox) were HTN (6/16), proteinuria (2/16) and palmar-plantar erythrodysesthesia (PPE) (2/16), with no G4/5 tox. Len+Let was active with 93.8% overall disease control rate (DCR) (50.0% partial response [PR], 43.8% stable disease [SD]). Among MBCts (8/12 had prior EB+CDK4/6i), DCR ≥12 wks was 91.7%; 1 pt had sustained PR for 48 wks and 1 ongoing PR at 40 wks. 9/16 pts had RET+ tumors on immunohistochemistry at baseline, and 66.7% showed down-regulation with Tx (RECIST: 4 PR, 2 SD). Conclusions: Len+Let showed significant anti-tumor activity, even in pts who failed prior CT or EB+CDK4/6i. RP2D of 14mg Len and 2.5mg Let is tolerated with efficacy; dose expansion is currently underway. Clinical trial information: NCT02562118. [Table: see text]

10536 Background: AYA cancer patients are relatively under-represented in clinical trials, with no published data regarding their outcomes in phase I studies. Trials utilizing novel therapeutic agents are often considered in these patients, due to their tendency to have good organ reserve, and ability to tolerate additional lines of therapy. This study describes the experience of AYA patients with advanced solid tumors treated in a specialized drug development unit. Methods: Patient characteristics and clinical outcomes of AYA patients (defined as age 15 to 39 years at time of initial cancer diagnosis) treated at the Drug Development Unit, Royal Marsden Hospital, United Kingdom, between 2002 and 2016, were captured and analyzed from case and trial records. Results: From a database of 2631 patients treated on phase I trials, 219 AYA patients (8%) were identified. Major tumor types included gynaecological cancer (24%), sarcoma (18%), gastrointestinal (16%) and breast cancer (11%). Patients had a median of 3 previous lines of systemic chemotherapy (range 0 – 6), and 19% participated in 2 or more phase I studies. Twenty (9%) had a known hereditary cancer syndrome (most commonly BRCA), 27% had a family history (FH) of cancer, 15% no FH and 49% no FH documented. Molecular characterization of tumors (n = 45) identified mutations most commonly in p53 (33%) , PI3KCA (18%) and KRAS (9%) . Major trial categories included DNA damage repair (16%), PI3K (16%) and anti-angiogenesis (15%) agents. Grade 3/4 toxicities were experienced in 25% of patients (10% hematological). Of the 214 evaluable patients, objective response rate was 12%, with clinical benefit rate at 6 months of 22%. Median progression free survival was 2.3 months (95% CI: 1.9 to 2.8), median OS was 7.6 months (95% CI: 6.3 to 9.5), and 2-year OS was 11%. Of patients with responses, 35% were matched to phase I trials based on germline or somatic genetic aberrations. Conclusions: A sub-group of AYA patients with advanced solid tumors derive considerable benefit from participating in trials involving novel therapeutics. Future research must focus on predictive biomarkers and molecular profiling to identify those that would benefit from novel therapies.

Greater understanding of the molecular classification of breast cancer has permitted the development of rational drug design strategies. In a phase I clinical trial setting, molecular profiling with next-generation sequencing of individual tumour samples has been employed to guide treatment. We conducted a retrospective evaluation of clinical outcomes of patients with metastatic breast cancer (MBC) treated in phase I clinical trials at our institution to assess the benefit of molecularly matched compared to non-matched treatments. A total of 97 consecutive patients with MBC were enrolled onto ≥1 trial between 2009 and 2015. Fourteen patients participated in multiple trials, and a total of 113 trial encounters were reviewed in this retrospective study. Eighty-three percent of patients with molecular data available were able to participate in trials matched to molecular aberrations. Patients who were treated on matched studies had improved clinical benefit (RR: 1.80, p = 0.005), progression-free (HR: 0.52, p = 0.003) and overall survival (HR: 0.54, p < 0.001). Treatment was well tolerated with low rates of treatment discontinuation for toxicity (8% overall) that did not differ between groups. No toxicity-related deaths were observed. Molecular profiling for MBC patients in a phase I setting is feasible and aids therapeutic decisions with improved patient outcomes.

10095 Background: Severe peripheral neuropathy is a common dose-limiting toxicity of paclitaxel chemotherapy, with no effective treatment. We have previously described the role of continuous-flow hypothermia in reducing neurotoxicity caused by paclitaxel. We hypothesized that cryocompression (addition of pressure to hypothermia) may enhance depth of cooling and improve efficacy. Methods: A proof-of-concept study was conducted in cancer patients receiving taxane chemotherapy. Each subject underwent four-limb cryocompression with each chemotherapy infusion (3 hours) for a maximum of 12 cycles. Cryocompression was administered at 16°C and cyclic pressure (5-15 mmHg). Skin surface temperature and tolerance scores were recorded. Neuropathy was assessed using nerve conduction studies (NCS) conducted before (NCSpre), after completion (NCSpost) and 3-months post chemotherapy (NCS3m). Results: In total, thirteen patients underwent 142 cycles of cryocompression concomitant with chemotherapy. Mean skin temperature reduction of 3.8 ± 1.7°C was achieved and was well tolerated. Only 1 out of 13 patients required an intra-cycle temperature increase, with no early termination of cryocompression in any subject. NCS analysis showed significant preservation of motor amplitudes at NCS3m compared to baseline (common peroneal nerve below fibula head stimulation: 12.7 ± 25.6 %; p = 0.013; tibial nerve abductor hallucis stimulation: 8.8 ± 22.9%; p = 0.005). Sensory nerve amplitudes showed a reduction at NCSpost compared to baseline but continued to be preserved at NCS3m (% change from baseline: (NCSpost) -28.1 ± 21.9 %; (NCS3m) -26.7 ± 19.0 %). Crycompression did not significantly affect taxane-induced changes in nerve velocities. Conclusions: Cryocompression is well tolerated and results in preservation of neuron function, as measured by gold-standard NCS. When compared to our previously reported continuous-flow hypothermia (21°C) cohort, cryocompression permitted delivery of lower temperatures with similar tolerability, potentially leading to improved efficacy in neurotoxicity amelioration. Larger studies investigating cryocompression are ongoing. Clinical trial information: NCT03299582.