Efficacy of Fulvestrant in Women with Hormone-Resistant Metastatic Breast Cancer (mBC): A Canadian Province Experience

Introduction: Fulvestrant has demonstrated efficacy in hormone receptor positive (HR+) metastatic breast cancer (mBC), both in first-and second-line settings. In clinical practice, however, fulvestrant has been used as a later-line therapy. This study assessed the efficacy of fulvestrant in women with mBC in early-versus later-line therapy. Methods: This retrospective cohort study assessed Saskatchewan women with HR+ mBC who received fulvestrant between 2003–2019. A multivariate Cox proportional survival analysis was performed. Results: One hundred and eighty-six women with a median age of 63.5 years were identified—178 (95.6%) had hormone-resistant mBC, 57.5% had visceral disease, and 43.0% had received chemotherapy before fulvestrant. 102 (54.8%) women received ≤2-line-therapy, and 84 (45.2%) received ≥3 line-therapy before fulvestrant. The median time to progression (TTP) was 12 months in the early-treatment vs. 6 months in the later-treatment group, p = 0.015. Overall survival (OS) from the start of fulvestrant was 26 months in the early-treatment group vs. 16 months in the later-treatment group, p = 0.067. On multivariate analysis, absence of visceral metastasis, HR: 0.70 (0.50–0.99), was significantly correlated with better TTP, whereas post-fulvestrant chemotherapy, HR: 0.32 (0.23–0.47), clinical benefit from fulvestrant, HR: 0.44 (0.30–0.65), and absence of visceral metastasis, HR: 0.70 (0.50–0.97), were correlated with better OS. Conclusions: Fulvestrant has demonstrated efficacy as both early-and later-line therapy in hormone-resistant mBC. Our results show that women with clinical benefit from fulvestrant, who received post-fulvestrant chemotherapy, or had non-visceral disease, had better survival.

CYTOLOGICAL DIAGNOSIS OF LEISHMANIAL LYMPHADENITIS

Leishmaniasis is a chronic inammatory disease caused by obligate intracellular kinetoplast containing parasite of the genus Leishmania. Leishmaniasis produces varied group of clinical syndromes ranging from self-healing cutaneous ulceration to fatal visceral disease. In India it is endemic in Bihar, Sub-Himalayan regions and other north Indian states. We present a rare Cytology case of Leishmaniasis in a young boy, hailing from a non-endemic area, presenting as Isolated Inguinal Lymphadenopathy.

Efficacy of Fulvestrant in Women with Hormone-Resistant Metastatic Breast Cancer (mBC): A Canadian Province Experience

Introduction: Fulvestrant has demonstrated efficacy in hormone receptor positive (HR+) metastatic breast cancer (mBC), both in first- and second-line settings. In clinical practice, however, fulvestrant has been used as a later-line therapy. The study aimed to assess the efficacy of fulvestrant in women with mBC in early- versus later-line therapy. Methods: In this retrospective cohort study, women with HR+ mBC who received fulvestrant between 2003–2019 in Saskatchewan were assessed. A multivariate Cox proportional survival analysis was performed. Results: 186 women with a median age of 63.5 years were identified; 178 (95.6%) had hormone resistant mBC, 57.5% had visceral disease, and 43.0% had received chemotherapy before fulvestrant. 102 (54.8%) women received ≤ 2-line-therapy, and 84 (45.2%) received ≥ 3 line-therapy before fulvestrant. The median time to progression (TTP) was 12 months in the early-treatment vs. 6 months in the later-treatment group, p = 0.015. Overall survival (OS) from the start of fulvestrant was 26 months in the early-treatment group vs. 16 months in the later-treatment group, p = 0.067. On multivariate analysis, absence of visceral metastasis, HR: 0.70 (0.50–0.99), was significantly correlated with better TTP, whereas post-fulvestrant chemotherapy, HR: 0.32 (0.23–0.47), clinical benefit from fulvestrant, HR: 0.44 (0.30–0.65) and absence of visceral metastasis, HR: 0.70 (0.50–0.97), were correlated with better OS. Conclusions: Fulvestrant has demonstrated efficacy as both early- and later-line therapy in hormone-resistant mBC. Women with clinical benefit from fulvestrant, who received post-fulvestrant chemotherapy, or had non-visceral disease had better survival.

Real-world analysis of disease progression after CDK 4/6 inhibitor (CDKi) therapy in patients with hormone receptor positive (HR+)/HER2- metastatic breast cancer (MBC).

e13030 Background: CDKi with endocrine therapy (ET) is approved treatment of metastatic HR+/HER2- breast cancer based on PFS benefit vs ET alone. Outcomes data following CDKi discontinuation (dc) is limited, with trials ongoing in this setting. The reported phenomenon of rapid progression within 4 months of CDKi dc raises concern over CDKi impact on HR+/HER2- MBC biology. This study aims to define outcomes after CDKi dc and identify predictors of progression. Methods: This is a retrospective review of women ≥18 years with HR+/HER2- MBC who received CDKi between 4/1/14 and 12/1/19. Patient and tumor characteristics, pre and post CDKi tx, and reason for CDKi dc were collected. Time to event outcomes from date of CDKi dc (primary = PFS, secondary = Overall Survival, OS) were analyzed with Kaplan Meier estimators and Cox regression. Results: Analysis included 140 patients (median age 65 years), with most MBC (84%) arising from earlier stage disease. 51% of MBCs had visceral disease, and 66% received tx prior to CDKi. The most common CDKi was palbociclib (93%); and most common ET were letrozole (52%) and fulvestrant (40%). Median CDKi tx duration was 9 months (3.5 – 17.4) with 80% dc due to progression. Post CDKi txs included chemotherapy (44%), ET (24%), targeted tx (21%), no further tx (7%) and CDKi tx (4%). Median follow up was 12 months. mPFS post CDKi dc were 6.5 months (95% CI: 5.0 – 7.9) and 11.3 months (95% CI: 4.6 – 23.7) in patients who dc CDKi due to progression or other reasons, respectively (HR 1.77, 95%CI: 1.10-2.85). Among 112 patients who progressed on CDKi, estimated 4-month incidence of post CDKi progression or death was 31% (Table ). mOS post CDKi dc was 15.4 months (95%CI: 13.3-19.0) and mOS post CDKi initiation was 26.5 months (95% CI: 23.3 – 34.3). Visceral disease (HR 1.45, 95%CI: 1.01-2.08) and progression as reason for CDKi dc (HR 1.77, 95%CI: 1.1-2.85) were predictors of PFS (p < 0.05). Receiving fulvestrant with CDKi (HR 1.42, 95%CI: 0.96-1.0), prior chemotherapy in the metastatic setting (HR = 1.39, 95% CI: 0.90 – 2.14), and shorter CDKi duration were associated with non-significant increased risk of PFS. Conclusions: Rapid progression or death at 4 months occurred in 31% of MBCs following CDKi dc due to progression. Ongoing studies to define clinical and molecular characteristics of rapidly progressing tumors are underway to develop targeted tx approaches and improve outcomes.[Table: see text]

Real-world Indian scenario of CDK4/6 inhibitors (palbociclib and ribociclib) with endocrine therapy in upfront hormone positive metastatic breast cancer.

e13028 Background: CDK4/6 inhibitors (CDKi), in combination with endocrine therapy (ET), has become the standard of care in the treatment of hormone positive (HR+)/ HER2 neu negative metastatic breast cancer (MBC) patients. We evaluated clinical outcomes and toxicity in MBC patients, who have received ET with two CDKi, namely palbociclib and ribociclib. Methods: This is an ambispective, single institutional analysis of de-novo HR+ MBC patients treated with CDKi (palbociclib 125 mg and ribociclib 600 mg once a day for 21 days /28 days cycle) from November 2016- October 2020 at AIIMS, New Delhi, India. The primary endpoint was progression-free survival (PFS) and the secondary endpoint was response rate and toxicity. A total of 157 female patients were recruited in this study however the response and toxicity data were available in 120 cases. All premenopausal women received ovarian suppression or ovarian ablation. Results: A total of 120 patients were included in this study with a median age of 57 years (35-75) and 93 (77.5%) cases were postmenopausal. Twenty-three (19.1%) patients had a bone-only disease, 49 (40.9%) had bone and visceral disease and 48 (40%) had only visceral disease. In this study 91 (75.9%) patients received palbociclib and 29 (24.2%) received ribociclib. The median PFS was 18 months (4-36). Twenty four (20%) patients achieved a complete response, 69 (57.5%) patients attained partial response, 18(15%) patients had stable disease and 9 (7.5%) had disease progression. Grade 3–4 neutropenia, thrombocytopenia, and anaemia were observed in 18(15%), 8 (6.7%), and 4 (3.3%) cases respectively. None of the patients developed febrile neutropenia. Cutaneous, renal, hepatic, and gastrointestinal toxicity was observed in 1,1,3,4 cases respectively. Prolonged QTc was observed in one case. Grade 3 fatigue was observed in 7 cases. Dose interruption/delay (mean dose delay of 7 days), dose modification, and drug discontinuation were observed in 24 (20%), 12 (10%), and 10 (8.3%) of cases respectively. Conclusions: This is one of the largest real-world Indian data on CDK4/6 inhibitors on upfront HR+ MBC. Side effects are less than published literature with similar efficacy. Neutropenia was the most common side effect which was managed by brief dose interruption.

Clinicopathological characteristics of exceptional responders who achieve durable remissions beyond five years (DR5) in HER2+(H+) metastatic breast cancer (MBC).

1046 Background: The introduction of anti-H2 targeted therapies has resulted in substantially improved outcomes for patients (pts) with H+MBC, yet despite survival prolongation, most patients so-treated will still ultimately die from MBC. Some patients do however, achieved prolonged remissions. In this report we outline the long-term outcomes of patients with H+MBC who were treated in our institution, with at least five-year follow-up from the diagnosis of MBC. Methods: As part of our larger single-institution “Thousand Patient HER-2 Database”, we conducted a retrospective review of all patients in whom a diagnosis of H+MBC was made prior to December 2015 (range 2000-2015 years). The DR5 category included only those who had never experienced relapse or progression following initial anti-H2 therapy for MBC, and who were alive at 5 years. Patients were designated as (1) DR5, defined as never relapse with an overall survival (OS) > 5 years; (2) nonDR, which included those who had no or shorter remission, but also included nine pts who did achieve a 5 year CR, but who subsequently relapsed. OS was calculated from the date of diagnosis of MBC. The frequency distribution was assessed by Fisher’s Exact Test or Chi-Square Test, as appropriate. OS and PFS were calculated according to Kaplan Meier method, and evaluated by Log-rank test. Univariate and multivariate Cox proportional hazards regression analysis was used to evaluate the effect of clinicopathological features on OS and PFS. Results: A total of 245 patients diagnosed with advanced H+MBC were identified. The median survival was 38 months, (range 0.3 – 248 months). Among these, 85 patients (35%) experienced an OS > 5 years, with 34 designated as DR5. The median OS for DR5 was 117 months, whereas nonDR (n = 211) had median OS of 33 months. The median age was similar between groups (DR5 53 yrs vs nonDR 56 yrs). A higher incidence of visceral disease was present in nonDR compared to DR5 (69% vs 44%). Of all patients diagnosed with de novo H+MBC, 23% achieved DR5. Presence of visceral disease, number of metastases and site of metastases were statistically significant negative predictors of achieving DR5 (P < 0.05). Presence of ER positive disease was not associated with OS. Conclusions: A meaningful subset of patients (14%) with advanced H+MBC achieve prolonged remission beyond five years with H2 targeted therapy. Nearly one quarter of those with de novo H+MBC achieve DR5. As de novo H+MBC now constitutes a higher proportion of all H+MBC than it did in the pre-trastuzumab era, an increasing proportion of H+MBC may now be achieving DR5. Prospective identification of variables to predict DR5 could assist in the stratification of patients for whom additional therapy is needed.

Everolimus combined with endocrine therapy in advanced HR-positive, HER2-negative Chinese breast cancer patients: A retrospective study.

e13023 Background: The Food and Drug Administration (FDA) approves the combination of everolimus and exemestane for the treatment of advanced breast cancer patients who are hormone-receptor (HR) positive but human epidermal growth factor receptor-2 (HER2) negative. However, there is little real-world data on the everolimus in Chinese breast cancer patients. Endocrine therapy is the main treatment for advanced HR-positive, HER2-negative breast cancer patients which includes aromatase inhibitor (AI) or fulvestrant. Drug resistance and subsequent treatment after endocrine therapy are some of the most clinical concerns. CDK4/6 inhibitors and HDAC inhibitors are poorly available due to high price, and combined everolimus therapy can be a non-ignorable choice for advanced HR-positive, HER2-negative breast cancer patients. Methods: We retrospectively collected the treatment information of advanced breast cancer patients treated with everolimus from 2013 to 2020 in Zhejiang Cancer Hospital. Kaplan–Meier analysis and Cox regression methods were used to calculate and compare the progression-free survival (PFS). Results: The study finally enrolled 84 patients meeting the requirement, and patients were postmenopausal or premenopausal while received ovarian function suppression. And 54 patients were in the everolimus+AI group, 30 patients were in the everolimus+fulvestrant group. The median PFS in all 84 patients was 6.87 months, and the median overall survival (OS) was 28.87 months. The DCR in all 84 patients was 76.2%, and the most common grade 3-4 adverse event is stomatitis which is similar to other previous studies. Subgroup analyses were further performed based on everolimus combined with AI/fulvestrant. Patients were well-balanced in clinical characteristics in the two groups. Everolimus combined with fulvestrant group showed no superior to everolimus combined with AI group, 5.77 vs. 7.97 months (HR, 1.56; 95% CI, 0.92-2.65, P = 0.0735). Subgroup analyses showed everolimus combined with AI groups was superior to Everolimus combined with fulvestrant groups in some subgroups: postmenopausal group (HR, 0.50; 95% CI, 0.26-0.98); without bone metastasis group (HR, 0.22; 95% CI, 0.06-0.80); lung or pleura metastasis group (HR, 0.35; 95% CI, 0.16-0.77); visceral disease group (HR, 0.37; 95% CI, 0.20-0.69); previous therapy lines ≥ 4 group (HR, 0.44; 95% CI, 0.22-0.87). Conclusions: Everolimus combined with fulvestrant is not superior to everolimus combined with AI in HR-positive, HER2-negative breast cancer patients. For postmenopausal patients, patients without bone metastasis, and patients with visceral disease, everolimus combined with AI is a better choice.

A phase Ib study of xentuzumab plus abemaciclib and fulvestrant in patients (pts) with advanced hormone receptor-positive (HR+), HER2-negative breast cancer (BC) with visceral or non-visceral disease.

1057 Background: Cyclin-dependent kinase (CDK) 4 & 6 inhibitors plus endocrine therapy (ET) are standard of care for advanced HR+ BC. Combining xentuzumab, an insulin-like growth factor (IGF) ligand-neutralizing antibody, with ET and everolimus, suggested progression-free survival (PFS) benefit in pts with advanced HR+ BC and non-visceral disease. Activation of the IGF pathway leads to an increase in cyclin D1, providing a rationale for combining IGF and CDK4 & 6 inhibition. This prospective, open-label study is investigating xentuzumab plus abemaciclib, a CDK4 & 6 inhibitor, with fulvestrant. In dose-finding cohorts, the recommended phase II dose (RP2D) was determined as xentuzumab 1000 mg weekly intravenously plus abemaciclib 150 mg every 12h orally (Q12h). Here, we report preliminary data on disease control rate (DCR) from two expansion cohorts in pts with advanced HR+ BC with visceral (D1) or non-visceral disease (D2). Methods: Postmenopausal women with advanced/metastatic HR+ BC that had progressed on or after ET (including adjuvant ET) were enrolled. Pts could not have received >1 line of ET or any chemotherapy for metastatic disease. No prior CDK4 & 6 inhibitor therapy was permitted. Pts had to have ≥1 documented visceral metastasis in D1 and no visceral metastases in D2. Pts received xentuzumab weekly plus abemaciclib Q12h (at RP2D) plus fulvestrant 500 mg per label. Protocol primary endpoint was PFS rate at 18 months (mos). Secondary endpoints included DCR (complete response [CR], partial response [PR] and non-CR/non-progressive disease [PD] or stable disease [SD] lasting ≥24 weeks [wks]). Results: In D1/D2, 33/31 pts were treated: median age 60/53 years. 19 pts in D2 had bone-only, non-measurable disease. At data cut-off (Jan 2021), median treatment duration was 7.5/9.2 mos in D1/D2; 40 pts remain on treatment. In D1, DCR was 64%: 17 (52%) pts had PR and 4 (12%) had SD lasting ≥24 wks. In D2, DCR was 55%: 5 (16%) pts had PR, 10 (32%) had non-CR/non-PD lasting ≥24 wks and 2 (7%) had SD lasting ≥24 wks. Median duration of disease control was 10.9 mos in each cohort. Some pts had not reached 24 wks; full DCR data will be presented. Most common AEs are shown in the table (≥33% all-grade in either cohort). No hypo/hyperglycemia was reported. Conclusions: Xentuzumab plus abemaciclib and fulvestrant demonstrated encouraging disease control in pts with advanced HR+ BC with visceral and non-visceral disease. The safety profile was manageable, and consistent with the known profiles of the three agents. Clinical trial information: NCT03099174 .[Table: see text]

A phase II study evaluating the efficacy of enzalutamide and the role of ARv7 in metastatic castration-resistant prostate cancer (mCRPC) patients (pts) with visceral disease.

5052 Background: Enzalutamide is a second-generation androgen receptor inhibitor that showed to prolong survival in different setting of prostate cancer. Visceral metastases, occurring in 10–30% of mCRPC pts, have been associated with poor outcomes. Given the poor prognosis, trial investigating hormone therapies often excluded men with visceral disease, especially in the pre-docetaxel setting. To date, there are no prospective studies designed ad hoc to test hormone therapies in this subgroup of pts. Methods: In this open label phase II multicentre study mCRPC pts with visceral metastases were treated with enzalutamide 160 mg orally once daily as first or second line after docetaxel until progressive disease or unacceptable toxicity. Pts were eligible if they had documented measurable metastatic visceral disease (according to RECIST 1.1 criteria), including lesions in lung or liver or extraregional lymphnodes. Pts must have PSA progression or radiographic progression (according to PCWG2). Primary endpoint was to determine the clinical benefit, as measured by 3-months (mo) disease control rate (DCR) defined as the proportion of pts with best overall response of confirmed complete (CR) or partial responses (PR) or stable disease as per RECIST 1.1 at mo 3. Secondary endpoints were safety, quality of life (assessed by EQ-5D-5L e FACT-P questionnaire), pain assessment (by BPI-SF questionnaire). Exploratory objectives were to assess the association between ARv7 splicing variants (in CTCs samples) and treatment response/resistance. For CTC and ARv7 detection, we used the Adna test Prostate Cancer Panel. Results: From March 2017 through January 2021, 68 pts were enrolled at 6 Italian centres. One pt never started treatment because of withdrawal of consent. Median age was 70 years (IQR 65- 78). All pts presented with visceral disease at baseline: 27, 6, 55 pts presented with lung, liver and lymphnodes lesions, respectively. 26 pts presented with only one metastatic site, 22 pts with two, while the remaining part with multiple sites. 15 pts received a previous treatment with docetaxel in the mCRPC phase. The median follow-up was 10 mo. The median time on treatment was 8 mo. At mo 3, 24 pts presented a stable disease, 1 pt achieved a confirmed CR and 20 pts a PR for a 3 mo-DCR of 67% (45/67). Discontinuations due to adverse-events, disease-related death, or disease progression occurred in 6%, 7%, and 40% of pts, respectively. So far, only 26 patients were evaluated for baseline CTC and ARv7. Interestingly, 75% of patients experiencing a progression at month 3 were classified as ARv7 positive at baseline. Conclusions: The study met its primary endpoint showing enzalutamide is an active treatment option for men with mCRPC and visceral disease in both pre or post-docetaxel setting. CTCs status combined with ARv7 detection could be useful to personalize treatments. Clinical trial information: NCT03103724.

Evidence that a naturally occurring single nucleotide polymorphism in the RagC gene of Leishmania donovani contributes to reduced virulence

Leishmaniasis is a widespread neglected tropical disease transmitted by infected sand flies resulting in either benign cutaneous infection or fatal visceral disease. Leishmania donovani is the principal species responsible for visceral leishmaniasis, yet an atypical L. donovani has become attenuated in several countries including Sri Lanka and causes cutaneous leishmaniasis. Previous studies have identified 91 genes altered in the atypical cutaneous L. donovani compared to typical visceral disease associated L. donovani including mutations in the RagC and Raptor genes that are part of the eukaryotic conserved TOR pathway and its upstream sensing pathway. In the present study, we investigate whether the RagC R231C mutation present in atypical cutaneous L. donovani introduced into the virulent L. donovani 1S2D chromosome by CRISPR gene editing could affect virulence for survival in visceral organs. Through bioinformatic analysis, we further investigated the presence of sensing pathway components upstream of TOR in L. donovani including RagC complexing proteins, RagA and Raptor. L. donovani 1S2D edited to express mutant RagC R231C were viable in promastigote but had reduced visceral parasitemia in infected BALB/c mice. The RagC R231C mutant retained the ability to interact with RagA and gene knockout experiments revealed that although the RagA gene was essential, the RagC gene was not essential under promastigote culture conditions but was essential for survival in the liver of experimentally infected mice. These results provide evidence that the TOR associated sensing pathway plays a prominent role in L. donovani visceral disease and the RagC R231C mutation contributed to the atypical pathology of cutaneous L. donovani in Sri Lanka.