Abstract P1-15-04: Features of HER2+ metastasic patients (pts) from a prospective registry of advanced breast cancer (ABC), GEICAM/2014-03 (RegistEM)

Background: The RegistEM study is a non-interventional study that is providing prospective data from around 1900 ABC pts (females and males) diagnosed with advanced disease between 01/Jan/2016 and 31/Dec/2019, either after recurrence or at 1st diagnosis, in 38 Spanish sites representative of the national territory and whose investigators are GEICAM members. Methods: In the current analysis (cut-off date 10/May/2021, ongoing database), we describe the features of 279 pts included in the RegistEM study, with HER2+ (immunohistochemistry [IHQ] 3+, IHQ 2+ and in situ hybridization [ISH]+) tumors at any time of their ABC (5% after the 1st-line therapy). This subgroup has been evaluated because of the interest from a clinical perspective. Multivariate Cox analysis aiming to identify factors associated with overall survival (OS) were built. Results: 279 pts were identified, representing the 15% pts available in the database at the cut-off date. At first ABC diagnosis, 48% pts had recurrent BC (>12 months [mo] from initial BC diagnosis in 93%), 51% de novo metastatic BC and 1% unresectable locally advanced BC (ULABC). The median age was 59 years, 98% were white , 71% postmenopausal and only 1 male was part of this subset. Considering the BC subtype assessed in the most recent tumor lesion before the 1st-line therapy, 264 pts wereHER2 positive (67% with hormone receptor [HR]+). Family history of BC and/or ovarian cancer was reported in 31% pts, and an hereditary-risk genetic test was performed in 25% (66/267 pts). BRCA1/2 and TP53 mutations were reported in 4/20 and 4/19 pts, respectively, and p53 overexpression in 20/46 pts. Lymph nodes (56%), bone (49%), liver (34%), lung (33%), soft tissue (10%) and brain (8%) were the main metastatic sites. Additional data according to HR status and type of ABC are detailed in the table below. In HR- pts, bone metastases were less frequent and lymph nodes metastases more frequent compared to HR+ pts. Visceral disease was present in 68% pts and ≈75% had ≤3 (47% ≤2) locations involved. The most common therapies by line were: 1) 1st-line: CT + dual anti-HER2 blockade (3%), chemotherapy (CT) (almost in all pts taxane-based)+dual anti-HER2 blockade + endocrine therapy (ET) (mainly aromatase inhibitors) (35%), and ET + anti-HER2 blockade or ET + cyclin-dependent kinases 4/6 inhibitors (11%); 2) 2nd-line: anti-HER2 blockade (56%) [mostly an antibody-drug conjugate (90%)], CT + anti-HER2 blockade (18%) and ET + anti-HER2 blockade (14%); 3) 3rd-line: CT + anti-HER2 blockade (55%) and anti-HER2 blockade (22%). The median time-to-progressions to 1st-, 2nd- and 3rd-line were 14, 5, and 4 mo, respectively. A 4th-line therapy was reported in 52% of pts who received a 3rd-line. At database cut-off date, death was reported in 34% of pts. The median OS of this subset of pts was 41 mo (36-49). In a multivariate Cox regression analysis, the following variables were significantly related with worse survival (from ABC diagnosis): Brain (HR=2.62; 95% CI, 1.02-6.73) and Visceral no Brain involvement (HR=2.15; 95% CI, 1.02-4.53) compare to only soft tissue lesions; early stage at first diagnosis (HR=1.77; 95% CI, 1.15-2.73); HR- (HR=1.70; 95% CI, 1.11-2.60) and age (HR=1.04; 95% CI, 1.02-1.07). Conclusions: In this cohort of HER2+ pts with advanced disease, half of them had de novo ABC which was associated with better OS. The median PFS in 1st- and 3rd-line were slightly better in HR+ pts, and in 2nd-line was similar between HR+ and HR- cohorts.

HR+181 (67%)HR- 91 (33%)Recurrent EBC134 (48%)ULABC or de novo M1 145 (52%)Time to recurrence >12 mo in EBC pts., n8435125NALocation of metastaticsites, nBoneBrainLiverLungLymph nodesSoft tissue104 10 62 57 90 1829 9 3232 64 1059 15 36 47 51 2278 6 59 46 1056Líne123123123123n180935690492613385521446333Deaths, n211112111161715141584Therapies by line, nET/BT261922101910212100ET12441011022323CT/BT/ET935031038305830CT/BT4017307581552182366924CT3572353711211BT6431373651145143385The most frequent therapies, nCT + dual anti-HER2 blockade + ET8623331551CT + single-agent HER2 blockade + ET522CT + dual anti-HER2 blockade3493644391016252CT + single-agent HER2 blockade4825641588211521CT5573354711411ET*22105212162644ET + HER2 blockade1213411662782Anti-HER2 blockade6431073651145143382Median duration of treatment, mo125585310441064TTP (mo), median (range)15(1-47)5(1-32)5(0-18)11(2-38)5(1-27)4(2-12)12 (1-47)5(1-26)4(0-17)17(2-45)7(1-32)4(1-18)Median PFS, mo14561154------HR: hormone receptor; EBC: early breast cancer; ULABC: unresectable locally advanced breast cancer; M1: metastatic; mo: month; ET: endrocrine therapy; BT: biological therapy; CT: chemotherapy; TTP: time-to-progression; PFS: progression-free survival. *ET includes aromatase inhibitors or selective estrogen receptor degraders, as single-agents or combined with cyclin-dependent kinases 4/6 inhibitors.

Citation Format: Isabel Álvarez, Ángel Guerrero-Zotano, Josefina Cruz, Purificación Martínez, María Hernández, César A Rodríguez, Álvaro Rodríguez-Lescure, Silvia Antolín, Encarna Adrover, Raquel Andrés, Catalina Falo, Jose Ignacio Chacón, Ana Miguel, Sonia Servitja, Maria Galán Gramaje, Mireia Margelí Vila, César Gómez Raposo, María Jose Echarri, Rafael Villanueva, Ariadna TIbau Martorell, Silvia Varela Ferreiro, Ruth Campo, Juan Jose Miralles, Susana Bezares, Federico Rojo, Sara López-Tarruella. Features of HER2+ metastasic patients (pts) from a prospective registry of advanced breast cancer (ABC), GEICAM/2014-03 (RegistEM) [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 P1-15-04.

Real-world efficacy and safety of peptide receptor radionuclide therapy (PRRT) in gastroenteropancreatic neuroendocrine tumors (GEP-NETs)

364

Background: PRRT with 177Lu-Dotatate (Lutathera) is a radiolabeled somatostatin analog indicated treatment of somatostatin receptor (STTR) positive GEP-NETs. The study aims to establish the efficacy and safety of PRRT in GEP-NETs in a real-world setting. Methods: We conducted an observational, retrospective, multicentric study of 40 patients with GEP-NET treated with PRRT belonging to GGNET (Galician Research Group on Neuroendocrine Tumors) network at Nuclear Medicine Department of Santiago de Compostela University Hospital (Spain). Patients characteristics, overall survival (OS), progression-free survival (PFS), overall response rate (ORR) and toxicity data were retrospectively collected and analyzed. Results: Data from 40 patients (pts) treated between 2016 and 2020 were recorded in this study. Median age was 63.5 years (range 41-85) and 55% were male. The baseline ECOG PS 0/1/2 was 15 (37.5%)/16 (40%)/9 (22.5%). Tumor location was intestinal 26 pts (65%), pancreas in 11 pts (27.5%) and unknown origin in 3 pts (7.5%). 25 pts (62.5%) were none functioning. Tumor grade G1/G2/G3 were 17 pts (42.5%)/ 20 pts (50%)/ 3 pts (7.5%), and Ki 67 < 2/3-20/ > 20%/unknown was 11 pts (27.5%)/ 21 pts (52.5%)/ 3 pts (7.5%)/ 5 pts (12.5%), respectively. The most frequent site of metastasis was liver in 32 pts (80%), lymph nodes in 19 pts (47.5%), peritoneum 11 pts (27.5%) and bone 10 pts (25%). Surgery: 22 pts (55%) primary tumor surgery and 8 pts (20%) metastasectomy. Previous systemic treatments included somatostatin analogs (SSA) in 40 pts (100%), everolimus in 26 pts (65%) and sunitnib in 11 pts (27.5%), others 7 pts (17.5%). 34 pts (85%) completed 4 cycles of treatment (6 pts (15%) non-complete due to premature death). 35 pts were evaluable for early response (after 2 cycles of treatment). Early ORR and DCR were 2.8% and 74.2%, respectively. 26 pts were evaluable after finishing treatment (6 pts premature death and 8 pending evaluation). ORR and DCR were 19.2% and 92.3%. With a median follow up of 21 months, 14 pts (35%) had died. Median OS was not reached (NR) and median PFS was 27.2 m (95% CI 16.0-38.4m). Tumor grade G1-2 (p < 0.001), Ki 67 <20% (p = 0.002), primary tumor surgery (p = 0.039) and metastasectomy (p = 0.030) were associated with prolonged PFS. Mild adverse events were most frequent after the 1º doses in 27.5% patients, and medium-term toxicity was present in 25.6%, mainly hematological, G1-G2 25.6%, and G3 5%. Conclusions: 177Lu-Dotatate is a safe and effective treatment for those patients diagnosed with metastatic GEP-NET and positive somatostatin receptors, with an excellent clinical and radiological response. Furthermore, we have identified some predictive factors to OS that should be taken into consideration.

The role of systemic inflammatory factors in gastroenteropancreatic neuroendocrine tumors (GEP-NETs) treated with peptide receptor radionuclide therapy (PRRT)

371

Background: Inflammation plays a key role in the pathophysiology of many diseases, including cancer. Systemic inflammatory factors have been validated as indicators of ongoing systemic inflammation that could be predictive markers of poor prognosis for oncological outcomes. However, it is unknown the prognostic impact of systemic inflammation markers in patients with GEP-NETs treated with PRRT. Methods: We conducted an observational, retrospective, multicentric study of 40 patients with GEP-NET treated with PRRT belonging to GGNET (Galician Research Group on Neuroendocrine Tumors) network at Nuclear Medicine Department of Santiago de Compostela University Hospital (Spain). The systemic inflammatory markers were calculated as follows: NLR = neutrophil count/lymphocyte count, PLR = platelet count/lymphocyte count, MLR= monocyte count/lymphocyte count, ALB= albumin levels and dNLR = neutrophil count/ (leucocytes count – neutrophils count). For the calculation of the different ratios, baseline analysis and after the second dose were used. The cut-off values were determined as the median of each values, correlating them with progression-free survival (PFS). Results: Data from 40 patients (pts) treated between 2016 and 2020 were recorded. Median age was 63.5 years (range 41-85) and 55% were male. Baseline ECOG PS 0/1/2 was 15 (37.5%)/16 (40%)/9 (22.5%). Tumor location was intestinal 26 pts (65%), pancreas 11 pts (27.5%) and unknown origin 3 pts (7.5%). 15 pts (37.5%) were functioning. Tumor grade G1/G2/G3 were 17 pts (42.5%)/ 20 pts (50%)/ 3 pts (7.5%), and Ki 67 <2/3-20/>20%/unknown were 11 pts (27.5%)/ 21 pts (52.5%)/ 3 pts (7.5%)/ 5 pts (12.5%), respectively. The most frequent site of metastasis was liver 32 pts (80%), lymph nodes 19 pts (47.5%), peritoneum 11 pts (27.5%) and bone 10 pts (25%). Surgery: 22 pts (55%) primary tumor surgery and 8 pts (20%) metastasectomy. Previous systemic treatments included somatostatin analogs (SSA) 40 pts (100%), everolimus 26 pts (65%) and sunitnib 11 pts (27.5%), others 7 pts (17.5%). The baseline cutoff-values for NLR was 2.61, for PLR 110.14, for MLR 0.31, for ALB 4.2. and for dNLR 1.71. The cutoff-values after the 2nd dose for NLR was 2.3, for PLR 2.15, for MLR 0.3, for ALB 4.2 and for dNLR 1.48. With a median follow up of 21 months, 14 pts (35%) had died. Median PFS was 27.2 m (95% CI 16.0-38.4m) and OS was not reached (NR). Pts with baseline higher NLR (>2.61 vs. <2.61) had a significantly lower PFS: 15.8 m vs. NR (HR 0.181; 95% CI 0.051-0.638, p=0.03), which was also true for pts with elevated dNLR (>1.71 vs. <1.71): PFS 15.8 m vs. NR (HR 0.174; 0.049-0.614, p=0.03). Baseline PLR, ALB, MLR and NLR, PLR, ALB, dNLR and MLR values after the 2nd dose was not statistically significant for PFS. Conclusions: We have identified that baseline NLR and dNRL are significant predictive factors in patients with GEP-NETs treated with PRRT.

First results of a prospective registry in unresectable locally advanced or metastatic breast cancer patients: GEICAM/2014-03 (RegistEM)

1077

Background: In Spain there is limited prospective data for unresectable locally advanced breast cancer (ULABC) or metastatic breast cancer (MBC) patients (pts) treated as per clinical practice. RegistEM study will provide epidemiological, pathological and clinical data, including treatments given for different disease stages. Understanding the real distribution of the different BC subtypes is the primary objective. Methods: This is a non-interventional cohort study enrolling approximately 1,400 pts with advanced disease diagnosed from January 2016 to December 2018, either after recurrence or as first diagnosis, in 38 Spanish sites. Biological samples (primary tumor, metastatic lesions, blood) are currently being collected. In this first analysis, we include 489 pts who met study criteria before October 31, 2017. All data are described in two subgroups: on the most recent tumor lesion or on the primary breast tumor. Results: At first diagnosis, 67.9%, 31.5% and 0.6% of pts had early BC (EBC), MBC and ULABC, respectively. In the total analysis population, median age at diagnosis of advanced disease was 59.6 years, most of pts were white (98.2%), female (99.4%) and postmenopausal (70%). Family history of BC and ovarian cancer was reported in 5.7% pts. In ~390 pts BC clinical subtypes distribution was luminal B(HER2-)-like (~55%), luminal B(HER2+)-like (~16%), luminal A-like or triple negative (TN) (~10% each) and HER2 enriched-like (~8%). Median time to recurrence (years) in EBC pts was: luminal A-like 5.8, luminal B(HER2-)-like 5.1, luminal B(HER2+)-like 3.9, HER2 enriched-like 2.7 and TN 1.7. Bone (59%), visceral (58%) and lymph node (27%) lesions were the most frequent metastatic locations. The two most frequent therapies in first line consisted in: endocrine therapy (ET) (47%) and ET+biological therapy (BT) (29%) for luminal A-like; ET (32%) and ET+BT (32%) for luminal B(HER2-)-like; chemotherapy (CT)+ET+BT (43%) and CT+BT (24%) for luminal B(HER2+)-like; CT+BT (68%) and CT (16%) for HER2 enriched-like; CT (59%) and CT+BT (34%) for TN. Conclusions: These first data confirm that luminal B (HER2-)-like subtype is the most predominant in MBC.

Concurrent chemoradiation (CChRT) with bi-weekly docetaxel and cisplatin and thoracic radiotherapy for stage III non-small cell lung cancer (NSCLC): A phase II study from the Galician Lung Cancer Group

7549

Background: CChRT is recommended as the evidence-based approach for the management of patients (p) with locally advanced stage III NSCLC and a good performance status, although a clearly superior regimen has not been identified. The aim of our study was to evaluate the effectiveness and toxicities of CChRT with bi-weekly docetaxel (D) and cisplatin (C) and thoracic radiotherapy. Methods: 50 p with histologically confirmed inoperable locally advanced NSCLC, stage IIIAN2/IIIB (no pleural T4), PS 0-1 and adequate lung function (FEV1 > 1.1, V20 < 25%) were included: one cycle of D 75 mg/m2 on day 1 and C 40 mg/m2 days 1-2 followed at 21 days by CChRT with bi-weekly D 40 mg/m2 and C 40 mg/m2 for four courses, during conformal thoracic radiotherapy (66 Gys, 180 cGy/day). The primary objective was overall survival (OS); secondary objectives were progression free survival (PFS), response rate (RR) and toxicity. Median follow-up: 14,5 months. Results: The p characteristics were: mean age 59,1 years (34-75); male/female 44/6; squamous/adeno/large cell carcinoma: 52%/34%/14%; stage IIIAN2 14 p (28%) and stage IIIB 36 p (72%). All p were evaluable for response and toxicity. RR: 4 CR, 36 PR (RR 80%; 95% CI:69-91), 4 SD (8%) and 6 PD (12%). The median PFS was 13 months (95% CI:8-18) and median OS was 19 months (95% CI:14-24). The PFS and OS at 1/2 years were 52%/30% and 79%/40% respectively. A total of 50 cycles of D-C induction chemotherapy were given; main toxicities (NCI-CTC 3.0) per p Grade (g) 1-2/3-4 (%) were as follows: neutropenia 2/16; anemia 12/0; nausea/vomiting 28/2; diarrhea 22/4; there were two episodes of febrile neutropenia. Main toxicities per p in CChRT (D-C doses: 192, 3.8 per p; mean doses RT: 64,6 Gys) were g1-2/3 (%): neutropenia 28/6; anemia 60/0; esophagitis 52/4 and pneumonitis 34/0; there were four episodes of hospitalization: febrile neutropenia, 2 p and g3 esophagitis, 2 p. Conclusions: CChRT with bi-weekly docetaxel and cisplatin and thoracic radiotherapy is a feasible treatment option for inoperable locally advanced stage III NSCLC, showing good clinical efficacy and tolerability with acceptable long-term survival.

Erlotinib as frontline treatment for elderly patients (p) with advanced nonsquamous non-small cell lung cancer (nsNSCLC): GGCP044/09 study

e18040

Background: NSCLC is primarily a disease of older people with a median age of approximately 70 years (y) at diagnosis. Platinum combination chemotherapy (CT) has shown to be more effective than single agents but it is associated with more toxicity. Erlotinib is an EGFR TK inhibitor with a favourable toxicity profile and its oral administration makes it suitable to treat elderly p. No much is known about its efficacy and toxicities in this subpopulation, often under-represented in clinical trials. This Galician study aims to evaluate the efficacy and safety of erlotinib as 1st-line treatment (Tx) for elderly p with advanced nsNSCLC. Methods: Elderly p (≥70 years old) with stage IIIB/IV nsNSCLC were included in this prospective observational study. Erlotinib was orally administered at a dose of 150 mg daily until disease progression or intolerable toxicity. PFS (primary objective) and OS were measured from time of diagnosis. Results:A total of 31 p were enrolled. Baseline characteristics: Mean age 78 y (range 70-85); female 67.7%; adenocarcinoma (including BAC) 90.3%; never/current/former smokers (%): 54.8/16.1/22.6 (6.5% unknown), stage IV 84%; ECOG PS 0/1/2 (%): 6.4/45.2/48.4. The median PFS was 6.4 and the median OS was 9.9 months. Out of 26 evaluable p, 8 had PR and 8 SD, for an ORR of 30.8% and a DCR of 61.6%. The most common adverse event was skin rash, 38.7% (9.6% grade 3-4), diarrhoea, 25.8% (3.2% gr. 3-4) and asthenia, 19.3% (no gr 3-4 were reported). 5 p (16.1%) needed dose reduction and 3 p withdrew the Tx due to grade 3 diarrhoea, eye perforation and esofaghitis, respectively. EGFR mutational status was available for 10 p (32.2%); 4 p harboured activating mutations: 3 p achieved PR and 1 p SD. SLP of 31 (ongoing), 22.4 (ongoing), 13.6 and 9.8 months. Conclusions: These results in real-life settings confirm that erlotinib is an active and well tolerated agent as frontline Tx in elderly p (≥70) in nsNSCLC. Response rate is similar to that achieved with CT in younger people; benefit in PFS is modest, but median OS is acceptable, taking into account that half of the p had a PS of 2 EGFR mutation testing should be strongly encouraged among elderly p.

GGCP041/09: A Galician study of second-line erlotinib in patients with advanced non-squamous non-small cell lung cancer (nsNSCLC)

e18146

Background: Efficacy of oral erlotinib has been conclusively established in 2nd line setting (BR.21 and TRUST studies) and the outcomes are similar to those provided by other approved chemotherapeutical agents (TITAN study). Higher responses rates have been found in p with Asian ethnicity, adenocarcinoma, women and never smokers, where predictive EGFR mutations occur more frequently; even though erlotinib has a significant effect on survival in all subgroups of patients. This observational study evaluates the efficacy of 2nd line erlotinib in unselected p with nsNSCLC in 4 Galician institutions. Methods: Unselected p with advanced nsNSCLC were treated with 150 mg/day of erlotinib as 2nd line therapy until unacceptable toxicity or progressive disease. EGFR mutational status was retrospectively tested when feasible, and serum carcinoembryonic antigen (CEA) monitored during the treatment period. Results: Baseline characteristics of 45 p included at the time of this analysis: mean age of 61.7 yrs. (range: 38-83); 80% male; 73.3% adenocarcinoma; 71.1% stage IV; 7/69/24% PS ECOG 0/1/2; 29/33/38 % never/current/former smokers. EGFR activating mutation testing was performed in 24 p (53%) and 2 positive cases were found (8%), both with metastatic adenocarcinoma (stage IV). The median PFS was 3.3 (95% CI: 1.6-5.1) and the median OS 10 months (95% CI: 7.5-12.5). Among p without EGFR mutations, erlotinib conferred a median OS of 8.1 months (95% CI: 1.4-14.9). Out of 31 p evaluable, radiologic response was achieved in 7 p (22.6%), for an overall disease control rate of 45.2 %. No unexpected toxicities were reported: 60 % of p experienced cutaneous toxicity (6.6 % grade ¾), 22.2% asthenia (4.4% grade ¾) and 17.8% diarrhea (2.2% grade ¾). Only 3 p discontinued due to adverse events. Conclusions: This study confirms the efficacy and safety of 2nd line erlotinib in a clinical practice scenario and the outcomes in p with non-squamous NSCLC are equivalent to those reported with the chemotherapy for salvage therapy. Moreover, the absence of mutations does not preclude the benefit from the drug. Updated data of the study will be presented.