Selinexor: Changing the paradigm in patients with TP53 wild-type endometrial cancer?

Recurrent endometrial cancer (EC) remains a therapeutic challenge despite advancements in personalized medicine. SIENDO trial showed the potential clinical benefit of selinexor in patients with TP53 wild-type advanced/recurrent EC. The quest for novel therapeutic avenues and approaches continues as researchers seek a glimmer of hope in an area of uncertainty.

Immunotherapy in head and neck squamous cell carcinoma: An updated review

Squamous cell cancer of the head and neck (HNSCC) is the sixth most common cancer and is associated with significant morbidity and mortality. The tumor microenvironment for HNSCC is a complex interplay of immune cells, stromal cells, and cytokines amongst others. Immunotherapy acts as an effective antineoplastic agent by influencing this complex environment and includes immune checkpoint inhibitors (ICI). ICI have been approved in the frontline setting for recurrent and metastatic (R/M) HNSCC as well as platinum-refractory (second line) R/M HNSCC. However, recent clinical studies highlight that the response to immunotherapy varies, and different ICI, as well as different combination strategies play a crucial role in augmenting the efficacy of immunotherapy. An in-depth analysis and focused study of the immune contexture in patients with HNSCC receiving ICI remains critical. Many novel immunotherapies including CAR-T cell therapy, oncolytic virus therapy, and vaccines are underway. Ongoing trials are testing ICI in the neoadjuvant and adjuvant settings. Furthermore, identifying better biomarkers to target population that benefits from immunotherapy is of paramount importance. Pioneering the optimal combination regimen utilizing new novel immunotherapy has recently become a paradigm shift in the HNSCC treatment landscape. Herein, we summarize the clinical development with all ongoing clinical trials of immunotherapy in HNSCC.

Identification of KRASG12C Mutations in Circulating Tumor DNA in Patients With Cancer

KRAS is the most mutated proto-oncogene that has been identified in cancer, and treatment of patients with KRAS mutations remains an arduous challenge. Recently, KRAS^G12C mutation has attracted special interest because it is now considered potentially druggable with recently developed covalent small-molecule KRAS^G12C inhibitors. Nevertheless, to date, there have been no large-scale analyses of liquid biopsy that include testing for KRAS^G12C. Here, we performed a comprehensive analysis of KRAS^G12C mutations in multiple cancer types, as detected by circulating tumor DNA.

Clinical and Molecular Characterization of POLE Mutations as Predictive Biomarkers of Response to Immune Checkpoint Inhibitors in Advanced Cancers

PURPOSE

DNA polymerase epsilon is critical to DNA proofreading and replication. Mutations in POLE have been associated with hypermutated tumors and antitumor response to immune checkpoint inhibitor (ICI) therapy. We present a clinicopathologic analysis of patients with advanced cancers harboring POLE mutations, the pattern of co-occurring mutations, and their response to ICI therapy within the context of mutation pathogenicity.

METHODS

We conducted a retrospective analysis of next-generation sequencing data at MD Anderson Cancer Center to identify patient tumors with POLE mutations and their co-occurring mutations. The pathogenicity of each mutation was annotated using InterVar and ClinVar. Differences in therapeutic response to ICI, survival, and co-occurring mutations were reported by POLE pathogenicity status.

RESULTS

Four hundred fifty-eight patient tumors with POLE mutations were identified from 14,229 next-generation sequencing reports; 15.0% of POLE mutations were pathogenic, 15.9% benign, and 69.1% variant of unknown significance. Eighty-two patients received either programmed death 1 or programmed death ligand-1 inhibitors as monotherapy or in combination with cytotoxic T-cell lymphocyte-4 inhibitors. Patients with pathogenic POLE mutations had improved clinical benefit rate (82.4% v 30.0%; P = .013), median progression-free survival (15.1 v 2.2 months; P < .001), overall survival (29.5 v 6.8 months; P < .001), and longer treatment duration (median 15.5 v 2.5 months; P < .001) compared to those with benign variants. Progression-free survival and overall survival remained superior when adjusting for number of co-occurring mutations (≥ 10 v < 10) and/or microsatellite instability status (proficient mismatch repair v deficient mismatch repair). The number of comutations was not associated with response to ICI (clinical benefit v progressive disease: median 13 v 11 comutations; P = .18).

CONCLUSION

Pathogenic POLE mutations were associated with clinical benefit to ICI therapy. Further studies are warranted to validate POLE mutation as a predictive biomarker of ICI therapy.

Selinexor in combination with standard chemotherapy in patients with advanced or metastatic solid tumors

Selinexor, an oral selective inhibitor of nuclear export (SINE), was demonstrated to hinder the DNA damage repair (DDR) system by reducing DDR proteins while enhancing the killing of cancer cells by DDR-based therapeutics in vivo studies. In this single-center, multi-arm phase 1b study, selinexor with carboplatin, doxorubicin and cyclophosphamide (DC), irinotecan with fluorouracil and folinic acid (FOLFIRI), irinotecan, and capecitabine and oxaliplatin (XELOX), were employed as separate parallel arms. Eligible patients have relapsed/ metastatic refractory solid tumors following standard therapy or addition of selinexor to systemic therapy was appropriate. Nineteen patients were treated in the 5 arms. Tumor types included were colorectal (n  = 3), breast (n  = 3), neuroendocrine (n  = 2), ovarian (n  = 2), and pancreas cancers (n  = 2). All patients developed one treatment-related adverse events (TRAE). The most prevalent TRAE were thrombocytopenia (84%), nausea (68%), leukopenia (68%), neutropenia (63%), and fatigue (58%). The common grade 3/4 TRAE were neutropenia (42%), leukopenia (26%), and hyponatremia (21%). Three patients had dose-limiting toxicities (DLT) in 3 separate arms. Fourteen patients were evaluable for response. Although no patients achieved complete or partial response (CR or PR), seven patients attained stable disease (SD). Disease control rate (DCR) was 14%. The combination of oral selinexor with different standard chemotherapies showed limited clinical activity despite toxicity and DLT prevented further dose escalation. Optimizing supportive care, the utility of growth factors, and aggressive measures on antiemetics strategies remain tangible.

Trial registration ClinicalTrials.gov Identifier: NCT02419495. Registered 14 April 2015, https://clinicaltrials.gov/ct2/show/NCT02419495). Sponsor(s): Karyopharm Therapeutics

Precision therapy for RET-altered cancers with RET inhibitors

Rearranged during transfection (RET) is involved in the physiological development of some organ systems. Activating RET alterations via either gene fusions or point mutations are potent oncogenic drivers in non-small cell lung cancer, thyroid cancer, and in multiple diverse cancers. RET-altered cancers were initially treated with multikinase inhibitors (MKIs). The efficacy of MKIs was modest at the expense of notable toxicities from their off-target activity. Recently, highly potent and RET-specific inhibitors selpercatinib and pralsetinib were successfully translated to the clinic and FDA approved. We summarize the current state-of-the-art therapeutics with preclinical and clinical insights of these novel RET inhibitors, acquired resistance mechanisms, and future outlooks.

Selinexor in combination with carboplatin and paclitaxel in patients with advanced solid tumors: Results of a single-center, multi-arm phase Ib study

Background. Carboplatin and paclitaxel (CT) is one of the standard chemotherapy regimens used in various tumor types. Preclinical models have suggested that selinexor, a first-in-class oral potent selective inhibitor of nuclear export Exportin-1, and CT exerts antitumor activity in multiple malignancies. Methods. This was a single-center, multi-arm phase Ib study utilizing a “basket type” expansion. CT and selinexor was employed as one of the 13 parallel arms. Advanced relapsed/refractory solid tumors following standard therapy or where the addition of selinexor to standard regimens deemed appropriate, were eligible. Results. Of 13 patients treated, 12 patients were evaluable for response. The most common cancers were breast (n = 4), esophageal (n = 2), ovarian (n = 2) and non-small cell lung cancers (n = 2). All 13 patients had at least one treatment-related adverse events (TRAEs) and the most common were neutropenia (85%), leukopenia (85%), thrombocytopenia (85%), anemia (69%), nausea (54%), vomiting (46%), and fatigue (46%). One patient at 60 mg QW experienced DLT with grade 3 nausea and vomiting lasting 3 days. Unconfirmed partial response (uPR) was observed in 3 patients; one patient each with esophageal, breast, and ovarian cancer. One patient with esophageal adenocarcinoma had confirmed PR, however, was discontinued from the study due to clinical progression. Five patients achieved stable disease (SD). Disease control rate was 8%. Majority of patients (77%), including two patients who had uPR, had prior exposure to carboplatin and/or paclitaxel. Time-to-treatment failure (TTF) ranged from 1 to 153 weeks. Conclusion. The RP2D of selinexor was 60 mg QW in combination with CT. The combination conferred viable clinical activity with durable objective responses which should further be explored in tumor types for which CT is used as standard of care. Trial information. ClinicalTrials.gov Identifier: NCT02419495. Sponsor(s): Karyopharm Therapeutics. (Trial registration: NCT02419495. Registered 14 April 2015, https://clinicaltrials.gov/ct2/show/NCT02419495).

Tissue-Agnostic Drug Development: A New Path to Drug Approval

In recent years, there has been remarkable progress in our understanding of cancer biology, host responses, and the concept of precision oncology. These advances have focused attention on biomarker-driven, tissue-agnostic drug development strategies. The recent approvals by the FDA of pembrolizumab for the treatment of unresectable or metastatic, microsatellite instability-high or deficient mismatch repair solid tumors, and more recently for the treatment of tumor mutational burden-high tumors; and of larotrectinib and entrectinib for the treatment of neurotrophic tyrosine kinase (NTRK) fusion-positive solid tumors, have further heightened interest in target-driven as opposed to histology-driven drug development. Herein, we focus on tissue-agnostic clinical drug development with an understanding of target modulation in the context of histology. The use of molecular genetics and biomarker-driven strategies rather than traditional histology based on organ of origin has reinforced the concept of tissue-agnostic drug development. Recent approvals in the United States, Europe, Japan, Australia, and other regions have further heightened interest in target-driven as opposed to histology-driven drug development.

Acalabrutinib‐related second primary malignancies and nonmelanoma skin cancers in patients with chronic lymphocytic leukaemia (CLL): A systematic review and meta‐analysis of randomised controlled trials (RCTs)

Acalabrutinib is a second generation Bruton's tyrosine kinase inhibitor and was recently approved in the treatment of chronic lymphocytic leukaemia. We undertook a systematic review and meta‐analysis of randomised controlled trials to determine the risks of acalabrutinib‐related second primary malignancies (SPM) and nonmelanoma skin cancers (NMSC). The incidence of SPM was 4.7% higher in the acalabrutinib arm compared to control arm with risk ratio (RR) of 1.76 (5.32 vs 3.2 per 100 person‐years). Notably, NMSC was the most common SPM, and the incidence was 2.56 per 100 person‐years in the acalabrutinib group versus 1.12 per 100 person‐years in the control group (RR 2.43). Long‐term follow‐up and future studies are necessary to define the actual relationship and their risk factors.

Therapeutics Targeting Mutant KRAS

Aberrations in rat sarcoma (RAS) viral oncogene are the most prevalent and best-known genetic alterations identified in human cancers. Indeed, RAS drives tumorigenesis as one of the downstream effectors of EGFR activation, regulating cellular switches and functions and triggering intracellular signaling cascades such as the MAPK and PI3K pathways. Of the three RAS isoforms expressed in human cells, all of which were linked to tumorigenesis more than three decades ago, KRAS is the most frequently mutated. In particular, point mutations in KRAS codon 12 are present in up to 80% of KRAS-mutant malignancies. Unfortunately, there are no approved KRAS-targeted agents, despite decades of research and development. Recently, a revolutionary strategy to use covalent allosteric inhibitors that target a shallow pocket on the KRAS surface has provided new impetus for renewed drug development efforts, specifically against KRAS^G12C. These inhibitors, such as AMG 510 and MRTX849, show promise in early-phase studies. Nevertheless, combination strategies that target resistance mechanisms have become vital in the war against KRAS-mutant tumors.

Efficacy of daratumumab combination regimen in patients with multiple myeloma: A combined analysis of phase III randomized controlled trials

The use of the CD38 monoclonal antibody daratumumab in combination with standard myeloma chemotherapy regimens has been studied extensively in recent years. We undertook an updated meta‐analysis of phase III randomized controlled trials (RCT) to determine the efficacy of daratumumab combination regimens. The relative risk for progression was significantly lower in daratumumab‐treated cohorts (HR 0.46, 95% CI 0.38‐0.55) and this was consistent across newly diagnosed and relapsed cases. No statistically significant improvement was identified in newly diagnosed patients with high‐risk cytogenetics and this group remains a therapeutic challenge.

CLO19-051: CDK 4/6 Inhibitor-Associated Hematologic Toxicities and Febrile Neutropenia in Patients With Hormone Receptor-Positive HER2-Negative Metastatic Breast Cancer

Background: Breast cancer is the most common cancer in women, and the majority of breast cancers express the estrogen receptor or progesterone receptor. Inhibition of CDK4/6 signaling pathway has shown survival benefit in advanced breast cancer by overcoming endocrine therapy resistance. Yet, there are considerable hematologic toxicities associated with CDK 4/6 inhibitors and hence, we performed a systematic review and meta-analysis of randomized controlled trials (RCT) to determine the risk. Methods: MEDLINE, EMBASE databases, and meeting abstracts from inception through September 2018 were queried. RCTs that mention anemia, thrombocytopenia, leukopenia, neutropenia, and neutropenic fever as adverse effects were incorporated in the analysis. Mantel-Haenszel method was used to calculate the estimated pooled risk ratio (RR) and risk difference (RD) with 95% CI. Random effects model was applied. Results: 8 RCTs (7 phase III and 1 phase II studies) with a total of 4,557 patients were eligible. The study arms used palbociclib/ribociclib/abemaciclib with letrozole or anastrozole or fulvestrant or other hormonal agent while the control arms utilized placebo in combination with letrozole or anastrozole or fulvestrant or other hormonal agent. The RR of all-grade side effects were as follows: anemia, 3.494 (95% CI: 2.535–4.814; P<.0001); thrombocytopenia, 6.066 (95% CI: 3.055–12.046; P<.0001); leukopenia, 10.376(95% CI: 7.236–14.879; P<.0001); and neutropenia, 14.387 (95% CI: 10.877–19.031; P<.0001). The RR of high-grade adverse effects were as follows: anemia, 2.251 (95% CI: 1.393–3.637; P=.001); thrombocytopenia, 3.696 (95% CI: 1.417–9.642; P=.008); leukopenia, 22.083(95% CI: 12.126–40.217; P<.0001); neutropenia, 33.527(95% CI: 17.271–65.082; P<.001). Neutropenic fever was noted in 71 (3.73%) in CDK 4/6 inhibitors group vs 28 (2.18%) in control arm. The pooled RR was statistically significant at 12.056 (95% CI: 1. 352–3.127; P=.001) and RD was 0.014 (95% CI: −0.002–0.029; P=.078) Conclusion: CDK 4/6 inhibitors–based regimen significantly contributed to all hematologic toxicities as well as febrile neutropenia. The improved efficacy outcomes and manageable toxicities with CDK 4/6 inhibitors are observed with proper supportive care and close monitoring.

CLO19-025: Treatment Discontinuation Due to Adverse Events and the Risk of Gastrointestinal Toxicities in Patients With Hematologic Malignancies Treated With Ibrutinib

Background: Ibrutinib targets Bruton’s tyrosine kinase, a kinase involved in signaling of B-cell and chemokine receptors, which are implicated in the pathogenesis of hematologic malignancies. Ibrutinib has been shown to improve survival in hematologic malignancies, and yet the tolerability has not been elucidated. We undertook systematic review and pooled analysis of randomized controlled trials (RTCs) to determine the risk of gastrointestinal toxicities and the rate of treatment discontinuation due to adverse events. Methods: We performed a comprehensive literature search using MEDLINE, EMBASE databases and meeting abstracts through September 2018. Phase 3 RCTs that mention gastrointestinal toxicities and the rate of treatment discontinuation due to adverse events were incorporated in the analysis. Mantel-Haenszel method was used to calculate the estimated pooled risk ratio with 95% CI. Random effects model was applied. Results: 6 phase III RCTs with a total of 1,811 patients with chronic lymphocytic leukemia/small lymphocytic lymphoma, mantle cell lymphoma, and Waldenstrom’s macroglobulinemia were included. Studies comparing ibrutinib vs ofatumumab, ibrutinib vs chlorambucil, ibrutinib + bendamustine + rituximab vs placebo + bendamustine + rituximab, ibrutinib vs temsirolimus, and ibrutinib vs rituximab were included in the analysis. The incidence of treatment discontinuation due to adverse events was 9.30% in the ibrutinib group vs 13.13% in the control arm. The relative risk (RR) for treatment discontinuation was 0.740 (95% CI: 0.385–1.423; P=.367). The pooled RR of all-grade side effects were as follows: diarrhea, 1.955 (95% CI: 1.304–2.933; P=.001); nausea, 1.038 (95% CI: 0.702–1.534; P=.852); vomiting, 1.048 (95% CI: 0.547–2.007; P=.888); and stomatitis, 1.262 (95% CI: 0.112–14.173; P=.850). The RR of high-grade adverse effects were as follows: diarrhea, 1.749 (95% CI: 0.866–3.530; P=.119); nausea, 2.237 (95% CI: 0.478–10.471; P=.306); vomiting, 0.429 (95% CI: 0.111–1.659; P=.220); and stomatitis, 0.309 (95% CI: 0.028–3.440; P=.340). Conclusion: Our study demonstrated that patients on ibrutinib arm noted increased risk of all-grade diarrhea. Nevertheless, other GI toxicities as well as treatment discontinuation due to adverse events were not statistically significant in the ibrutinib group compared with the control arm.

EPR19-071: Risk of Hematologic Toxicities and Health-Related Quality of Life Events in Patients With Hematologic Malignancies Treated With Ibrutinib: A Combined Analysis of 6 Phase III Trials

Background: Bruton’s tyrosine kinase (BTK) is essential for signaling of B-cell and chemokine receptors. Ibrutinib targets BTK and has become frontier in many hematologic malignancies. We undertook systematic review and pooled analysis of randomized controlled trials (RCTs) to determine the risk of hematologic toxicities and health-related quality of life (HRQOL) events associated with ibrutinib. Methods: We performed a comprehensive literature search using MEDLINE, EMBASE databases, and meeting abstracts through September 2018. Phase III RCTs that mention hematologic toxicities and HRQOL events as adverse effects were incorporated in the analysis. Mantel-Haenszel method was used to calculate the estimated pooled risk ratio with 95% CI. Random effects model was applied. Results: 6 phase III RCTs with a total of 1,811 patients with chronic lymphocytic leukemia/small lymphocytic lymphoma, mantle-cell lymphoma, and Waldenstrom’s macroglobulinemia were eligible. Studies compared Ibrutinib (I) vs ofatumumab, I vs chlorambucil, I+ bendamustine (B) + rituximab (R) vs placebo + B+ R, I vs temsirolimus and I vs R were included in the analysis. The relative risks (RR) of all-grade side effects were as follows: anemia, 0.812 (95% CI: 0.565–1.168; P=.261); neutropenia, 0.956 (95% CI: 0.720–1.268; P=.754); thrombocytopenia, 1.054 (95% CI: 0.450–2.470; P=.904); fatigue, 0.896 (95% CI: 0.761–1.056; P=.192); pyrexia, 1.123 (95% CI: 0.893–1.413; P=.322); and arthralgia, 1.863 (95% CI: 1.101–3.152; P=.020). The RR of high-grade adverse effects were as follows: anemia, 0.522 (95% CI: 0.371–0.733; P<.0001); neutropenia, 0.969 (95% CI: 0.751–1.249; P=.807); thrombocytopenia, 0.608 (95% CI: 0.252–1.470; P=.270); fatigue, 0.618 (95% CI: 0.396–0.964; P=.034); pyrexia, 1.165 (95% CI: 0.534–2.542; P=.701); and arthralgia, 3.623 (95% CI: 0.743–17.663; P=.111). Conclusion: Ibrutinib increased the risk of all-grade arthralgia whereas the risks of high-grade anemia and fatigue were significantly lower in the study arm, favoring ibrutinib.

CLO19-050: Risk of Health- Related Quality of Life (HRQOL) Events in Patients With Advanced Solid Tumors Treated With Cabozantinib: A Combined Analysis of Four Phase 3 Randomized Controlled Trials

Background: VEGFR, KIT, RET, and MET pathways are implicated in several solid tumors. Cabozantinib is an oral inhibitor of these kinase pathways, and hence has found its use in treatment of multiple malignancies. However, it has several side effects that can limit tolerance amongst patients. We performed a systematic review and meta-analysis of randomized controlled trials (RCT) to determine the risk of health-related quality of life (HRQOL) events in patients with advanced solid tumors treated with cabozantinib. Methods: We systematically conducted a comprehensive literature search using MEDLINE, EMBASE databases, and meeting abstracts through September 30, 2018. Phase 3 trials that mention HRQOL events like pain, arthralgia, fatigue, and reduced appetite as adverse effects were incorporated in the analysis. Mantel-Haenszel method was used to calculate the estimated pooled risk ratio (RR) with 95% CI. Random effects model was applied. Results: 4 phase 3 RCTs with a total of 2,703 patients with medullary thyroid cancer, prostate cancer, renal cell carcinoma, and hepatocellular carcinoma were eligible. Studies comparing cabozantinib (C) vs everolimus, C vs placebo, C vs prednisone were included in the analysis. The relative risks of all-grade side effects were as follows: fatigue, 1.378 (95% CI: 1.236–1.536; P<.0001); asthenia, 1.704 (95% CI: 1.190–2.441; P=.004); reduced appetite, 2.088 (95% CI: 1.471–2.964; P<.0001); back pain, 1.047 (95% CI: 0.871–1.259; P=.626); pain in limbs, 1.444 (95% CI: 1.128–1.847; P=.004); arthralgia, 0.982 (95% CI: 0.707–1.363; P=.912). The RR of high-grade side effects were as follows: fatigue, 1.937 (95% CI: 1.483–2.528; P<.0001); asthenia, 2.211 (95% CI: 1.536–3.184; P<.0001); reduced appetite, 4.329 (95% CI: 2.372–7.900; P<.0001); back pain, 1.227 (95% CI: 0.738–2.040; P=.431); pain in limbs, 2.933 (95% CI: 1.127–7.635; P=.028); arthralgia, 0.820 (95% CI: 0.394–1.709; P=.597). Conclusion: Our meta-analysis showed that cabozantinib contributed to significant toxicity of all grades of fatigue, asthenia, pain in limbs, and reduced appetite. Identifying and addressing these toxicities will be important in improving quality of life for these patients.

EPR19-73: Risk of Gastrointestinal and Hepatic Toxicities in Patients With Hormone Receptor-Positive HER2-Negative Metastatic Breast Cancer Treated With CDK4/6 Inhibitors

Background: CDK4 and CDK6 are cyclin-dependent kinases that control transition between G1 and S phases of the cell cycle, hence controlling cell cycle progression by reversible combination with cyclin D1. In cancer cell, CDK4/6 activity is overexpressed, which can lead to amplification or overexpression of the genes encoding for CDK 4/6 or the cyclin D. Additionally, loss of endogenous INK4 inhibitors can also lead to over activity of CDK4 and CDK6. We undertook a meta-analysis of randomized controlled trials (RCT) to determine the risk of gastrointestinal (GI) and hepatic toxicities associated with CDK 4/6 inhibitors. Methods: We conducted a comprehensive literature search using MEDLINE, EMBASE databases, and meeting abstracts from inception through September 2018. In our analysis, we incorporated RCTs that mention GI toxicities and elevation of aspartate aminotransferase (AST) or alanine aminotransferase (ALT) as adverse effects. Mantel-Haenszel (MH) method was used to calculate the estimated pooled risk ratio (RR) with 95% CI. Random effects model was applied. Results: A total of 4,557 patients with advanced breast cancer from 7 phase III and 1 phase II RCTs were eligible. The study arms used were palbociclib/ribociclib/abemaciclib or placebo in combination with letrozole or anastrozole or fulvestrant or other hormonal agents. The RR of all-grade side effects were as follows: diarrhea, 1.691 (95% CI: 1.220–2.345; P=.002); nausea, 1.632 (95% CI: 1.447–1.840; P<.001); vomiting, 1.684 (95% CI: 1.256–2.259, P=.001); stomatitis, 2.160 (95% CI: 1.332–3.503; P=.002); elevated AST, 1.832 (95% CI: 1.312–2.558; P<.001); and elevated ALT, 2.150 (95% CI: 1.649–2.803; P<.001). The RR of high-grade side effects were as follows: diarrhea, 2.592 (95% CI: 0.853–7.877; P=.093); nausea, 1.326 (95% CI: 0.589–2.988; P=.496); vomiting, 1.089 (95% CI: 0.479–2.476; P=.839); stomatitis, 2.097 (95% CI: 0.502–0.753; P=.310); elevated AST, 2.274 (95% CI: 1.173–4.410; P=.015); and elevated ALT, 3.988 (95% CI: 2.387–6.663; P<.001). Conclusions: Our study demonstrated that the risk of developing all grade GI toxicities and all grades of hepatic side effects including grade 3 and 4, was high in CDK 4/6 inhibitors group, compared to control arm, and prompt intervention with good supportive care is required.

CLO19-052: Incidence of Ribociclib-Associated Cardiac Conduction Abnormalities in Patients With Hormone Receptor-Positive HER2-Negative Metastatic Breast Cancer: A Combined Analysis of 3 Phase III Randomized Controlled Trials

Introduction: Ribociclib, a cyclin-dependent kinase 4/6 inhibitor, has improved survival in patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER 2)-negative advanced breast cancer. Despite remarkable efficacy, potential cardiac toxicities remain a concern. We undertook a combined analysis of randomized controlled trials (RCT) to estimate the incidence of prolongation of corrected QT interval (QTcF) associated with ribociclib. Methods: We performed systematic search of Embase, MEDLINE, and meeting abstracts till September 30, 2018, to find all phase 3 RCTs comparing ribociclib with other agents or placebo in patients with advanced breast cancer and reporting QTc prolongation as adverse event. Mantel-Haenszel method was used to calculate the pooled risk ratio (RR) and absolute risk difference (RD) with 95% CI. Fixed effects model was applied. Heterogeneity was assessed using I2 statistic. Results: Three phase III studies with 2,062 participants were included. Randomization ratio was 1 to 1 in MONALEESA-2 and 7 studies and 2 to 1 in MONALEESA-3 study. I2 statistic was 0, suggesting homogeneity across studies. Prolongation of QTcF >60 msec from baseline was observed in 72 patients (61 had post-baseline QTcF >480 msec) in ribociclib arm, compared to 7 in control arm. Pooled RR for prolongation of QTcF was 7.956 (95%CI: 3.683–17.187; P<.001) and RD was 0.055 (95%CI: 0.040–0.070; P<.001). The risk of having a post-baseline QTcF >480 msec was significantly higher with ribociclib vs control (pooled RR, 4.002; 95%CI: 2.161–7.412; P<.001; and RD, 0.039; 95%CI: 0.024–0.055; P<.001). A total of 16 (1.38%) patients in the ribociclib arm had dose reduction, interruption, or discontinuation due to QTcF prolongation, as opposed to 3 (0.33%) in control arm. Pooled RR and RD were statistically significant at 4.204 (95%CI: 1.333–3.260; P=.014) and 0.012 (95%CI: 0.004–0.021; P=.006), respectively. Conclusion: Advanced breast cancer patients may have cardiac dysfunction due to prior cardiotoxic chemotherapies. In our meta-analysis, ribociclib was associated with significantly higher risk of QTc prolongation and the resultant dosing inconsistencies and discontinuation. Early detection of this potential adverse event and timely intervention are critical.

CLO19-053: Incidence of Cabozantinib-Associated Palmar-Plantar Erythrodysesthesia and Hypertension in Patients With Metastatic Solid Tumors: A Combined Analysis of 4 Phase III Randomized Controlled Trials

Background: Tyrosine kinases such as VEGFR, KIT, RET, MET are implicated in development and progression of several solid tumors. Cabozantinib is an oral multiple tyrosine kinase inhibitor and has shown survival benefits in several solid tumors. Yet, there are notable toxicities. We performed a systematic review and meta-analysis of randomized controlled trials (RCT) to determine the risk of palmar-plantar erythrodysesthesia (PPE) and hypertension in patients with metastatic solid tumors treated with cabozantinib. Methods: We systematically conducted a comprehensive literature search using MEDLINE, EMBASE databases, and meeting abstracts through September 2018. Phase III RCTs that mention PPE and hypertension as adverse effects were incorporated in the analysis. Mantel-Haenszel method was used to calculate the estimated pooled risk ratio (RR), and risk difference (RD) with 95% CI. Random effects model was applied. Heterogeneity was assessed using I2 statistic. Results: 4 phase III RCTs with total of 2,703 patients, comparing cabozantinib (C) vs everolimus, C vs placebo, C vs prednisone, were included. I2 statistic was 70.70, suggesting some heterogeneity among RCTs. All grade-PPE incidence was 666 (39.3%) in cabozantinib arm vs 38 (3.76%) in control arm with a RR of 11.378 (95% CI: 6.545–19.782; P<.0001). The absolute RD was 0.383 (95% CI: 0.294–0.473; P<.0001). High-grade PPE was reported in 172 (10.15%) in cabozantinib group vs 3 (0.29%) in control group with a RR of 19.077 (95% CI: 5.733–63.476; P<.0001). The RD was 0.105 (95% CI: 0.049–0.160; P<.0001). The overall incidence of hypertension was noted at 524 (30.95%) in cabozantinib arm vs 84 (8.31%) in control arm. The pooled RR of hypertension was 4.131 (95% CI: 2.656–6.425; P<.0001) and RD was 0.240 (95% CI: 0.186–0.295; P<.0001). High-grade hypertension was reported in 276 (16.30%) in cabozantinib group vs 41 (4.05%) in control group with a RR of 4.324 (95% CI: 2.484–7.525; P<.0001) and RD was 0.115 (95% CI: 0.085–0.144; P<.0001). Conclusion: Our meta-analysis demonstrated that cabozantinib contributed to significant toxicity of any-grade and high-grade PPE as well as hypertension, with a RR of 19.07 for grade 3 and 4 PPE. Recognizing these toxicities and prompt intervention with proper supportive care may enhance patients’ quality of life, ultimately leading to better compliance.

EPR19-74: Risk of Cabozantinib-Associated Gastrointestinal and Hepatic Toxicities in Patients With Metastatic Solid Tumors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Cabozantinib is an oral inhibitor of multiple tyrosine kinases and is used in treatment of multiple solid tumors, targeting several pathways such as vascular endothelial growth factor signaling pathway and proto-oncogenes MET, KIT, RET. These pathways are implicated in several tumor development and progression. We performed a systematic review and meta-analysis of randomized controlled trials (RCT) to determine the risk of gastrointestinal (GI) and hepatic toxicities among patients with metastatic solid tumors treated with cabozantinib. Methods: MEDLINE, EMBASE databases, and meeting abstracts from inception to September 2018 were queried. Phase 3 RCTs that mention GI and elevation of liver enzymes as adverse effects were incorporated in the analysis. Mantel-Haenszel method was used to calculate the estimated pooled risk ratio (RR) with 95% CI. Random effects model was applied. Results: We included 4 phase 3 RCTs with a total of 2,703 patients with various solid tumors. The study arm used cabozantinib while the control arm utilized everolimus or placebo or prednisone. The relative risks of all-grade side effects were as follows: diarrhea, 2.495 (95% CI: 2.149–2.897, P<.0001); nausea, 1.849 (95% CI: 1.649–2.072; P<.0001); vomiting, 2.335 (95% CI: 1.724–3.163; P<.0001); stomatitis, 4.541 (95% CI: 0.908–22.696; P=.065); dysgeusia, 4.428 (95% CI: 2.67–7.343; P<.0001); elevated AST, 2.002 (95% CI: 1.331–3.011; P=.001); and elevated ALT, 1.988 (95% CI: 0.936–4.222; P=.074). The RR of high-grade side effects were as follows: diarrhea, 5.913 (95% CI: 3.655–9.566; P<.0001); nausea, 3.098 (95% CI: 1.266–7.581; P=.013); vomiting, 1.298 (95% CI: 0.395–4.265; P=.668); stomatitis, 3.837 (95% CI: 0.749–19.665; P=.107); dysgeusia, 1.522 (95% CI: 0.159–14.574; P=.716); elevated AST, 1.733 (95% CI: 1.101–2.728; P=.018); and elevated ALT, 2.489 (95% CI: 1.164–5.326; P=.019). Conclusion: The risk of developing all grades of diarrhea, nausea, elevated AST, and any-grade vomiting, dysgeusia as well as high-grade elevated ALT, was high in cabozantinib group. Timely recognition and providing good supportive care will enhance patients’ quality of life.

CLO19-024: Risk of Atrial Fibrillation and Pulmonary Toxicities in Patients With Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma Treated With Ibrutinib

Background: Bruton’s tyrosine kinase (BTK), a kinase downstream of the B-cell receptor, involves in the B cell survival and proliferation and has become an attractive therapeutic target. Ibrutinib is an oral potent, covalent inhibitor of BTK and hence employed in many hematologic malignancies. We performed a systematic review and pooled analysis of randomized controlled trials (RCTs) to determine the risk of atrial fibrillation (AF) and pulmonary toxicities among patients treated with ibrutinib. Methods: We performed a comprehensive literature search using MEDLINE, EMBASE databases, and meeting abstracts through September 2018. Phase 3 RCTs that mention AF and pulmonary toxicities as adverse effects were incorporated in the analysis. Mantel-Haenszel method was used to calculate the estimated pooled risk ratio with 95% CI. Random effects model was applied. Results: 4 phase III RCTs with a total of 1,383 patients with chronic lymphocytic leukemia or small lymphocytic lymphoma were eligible. Studies comparing Ibrutinib (I) vs ofatumumab, I vs chlorambucil, I+ bendamustine (B)+ rituximab (R) vs placebo + B+ R, and I vs R were included in the analysis. The AF incidence was 41 (5.686%) in the ibrutinib group vs 8 (1.208%) in the control arm. The relative risk (RR) for AF was statistically significant at 3.825 (95% CI: 1.848–7.917; P<.0001) and RD was 0.041 (95% CI: 0.023–0.059; P<.0001). The RR of all-grade side effects was as follows: cough, 1.133 (95% CI: 0.724–1.773; P=.584); edema, 1.375 (95% CI: 0.943–2.006; P=.098); pneumonia, 1.227 (95% CI: 0.884–1.703; P=.221); and upper respiratory infections (URI), 1.075 (95% CI: 0.809–1.429; P=.616). The RR of high-grade side effects was as follows: cough, 0.373 (95% CI: 0.063–2.209; P=.277); edema, 1.232 (95% CI: 0.199–7.649; P=.822); pneumonia, 1.277 (95% CI: 0.847–1.926; P=.243); and URI, 1.555 (95% CI: 0.239–10.127; P=.644). Conclusion: Our meta-analysis demonstrated that patients on ibrutinib noted a significant increase in the risk of atrial fibrillation with a relative risk of 3.825. However, the risk of pulmonary toxicities was not statistically increased in the ibrutinib group.

Abstract P4-16-06: Incidence of interstitial lung disease in patients with HER2-positive advanced breast cancer treated with everolimus and trastuzumab: A combined analysis of two phase 3 randomized controlled trials

Background: The human epidermal growth factor receptor 2 (HER2) protein is overexpressed in approximately one fourth of breast tumors. Trastuzumab resistance has been demonstrated via aberrant PI3K/AKT/mTOR signaling due to PTEN loss. To circumvent this resistance mechanism, everolimus, an oral mTOR inhibitor, has been employed in treatment of HER2-positive advanced breast cancer (ABC). Lung toxicity due to everolimus is well established and has been reported with trastuzumab. Yet, the incidence of interstitial lung disease (ILD), when everolimus was added to trastuzumab, has never been reported. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) to determine the incidence of ILD in patients with HER2-positive ABC treated with both everolimus and trastuzumab.

Methods: We systematically conducted a comprehensive literature search using MEDLINE, EMBASE databases and meeting abstracts through January 2018. Phase 3 RCTs that mention ILD as an adverse effect were incorporated in the analysis. The primary meta- analytic approach was a fixed effects model using the Mantel-Haenszel (MH) method. It was used to calculate the estimated pooled risk ratio (RR), and risk difference (RD) with 95% confidence interval (CI).

Results: A total of 1272 patients with HER-2 positive ABC from two phase 3 RCTs were eligible. Studies compared everolimus + paclitaxel + trastuzumab vs paclitaxel + trastuzumab and everolimus + vinorelbine + trastuzumab vs vinorelbine + trastuzumab. The initial dose of everolimus in BOLERO-1 was 10mg per day and in BOLERO-3, 5mg per day was used. The median relative dose intensity of everolimus was reduced to 0.54 in BOLERO-1 due to toxicity related dose reductions and dose interruptions. The randomization ratio of everolimus to placebo was 2 to 1 in BOLERO-1 and 1 to 1 in BOLERO-3. Everolimus was utilized in trastuzumab-resistant ABC after prior taxane therapy in the BOLERO-3 study (n= 562) and as first-line treatment in the BOLERO-1 study (n= 710). The I2 statistic for heterogeneity was 0, and the heterogeneity X2 (Cochran's Q) was 1 (P= 0), suggesting homogeneity among RCT. The incidence of all-grade ILD was 31 (4.122%) in the everolimus group vs 3 (0.577%) in control group and of high-grade ILD was 11 (1.463%) in everolimus arm vs 0 (0%) in the control arm. The pooled RR for all-grade ILD was significant at 7.258 (95% CI: 2.130 – 24.733, p = 0.002) and the absolute RD was 0.035 (95% CI: 0.019 – 0.050, P &lt; 0.001). The pooled RR for high-grade ILD was noted at 7.930 (95% CI: 0.997 – 63.044, p = 0.050) and the absolute RD was 0.014 (95% CI: 0.004 – 0.024, P = 0.004).

Conclusions: Approximately 0.46 and 0.61% of patients on trastuzumab alone have been reported to develop ILD in previous studies. Our study showed that the addition of reduced dose of everolimus to trastuzumab, significantly contributed a higher incidence in all grades of ILD with a relative risk of 7.93 for grade 3 and 4 ILD. More randomized trials are required to determine the definitive incidence and actual relation of ILD as well as the optimal dose of everolimus, when combined with trastuzumab or other chemotherapy.

Citation Format: Thein KZ, Swarup S, Sultan A, Tijani L, D'Cunha N, Hardwicke FT, Awasthi S, Jones C. Incidence of interstitial lung disease in patients with HER2-positive advanced breast cancer treated with everolimus and trastuzumab: A combined analysis of two phase 3 randomized controlled trials [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-16-06.

Abstract P1-16-04: Risk of venous thromboembolism with abemaciclib based regimen versus other CDK 4/6 inhibitor containing regimens in patients with hormone receptor-positive HER2-negative metastatic breast cancer

Background: Approximately 70% of patients with metastatic breast cancer (MBC) are hormone receptor (HR) - positive and the cyclin dependent kinases (CDK) along with their D-type cyclin catalysts, have been shown to play a role in mediating the resistance to endocrine therapy. Several CDK-targeted agents have been recently approved by FDA. Nevertheless, the risk of venous thromboembolism (VTE) with the use of different CDK 4/6 inhibitors has never been reported. We undertook a systematic review and meta-analysis of randomized controlled trials (RCT) to determine the risk of VTE with abemaciclib based regimens versus other CDK 4/6 inhibitor containing regimens in patients with HR-positive HER2-negative MBC.

Methods: We systematically conducted a comprehensive literature search using MEDLINE, EMBASE databases and meeting abstracts through February 2018. The randomized controlled trials that mention deep vein thrombosis and pulmonary embolism as adverse effects of CDK 4/6 inhibitor therapy were incorporated in the analysis. The primary meta- analytic approach was a fixed effects model using the Mantel-Haenszel (MH) method. It was used to calculate the estimated pooled risk ratio (RR) and risk difference (RD) with 95% confidence interval (CI).

Results: Five phase 3 studies and one phase 2 study with a total of 3,159 patients with HR-positive HER2-negative MBC were eligible for analysis. The study arms used palbociclib-letrozole, palbociclib-fulvestrant, ribociclib-letrozole, abemaciclib-fulvestrant, and abemaciclib-nonsteroidal aromatase inhibitors (either letrozole or anastrozole) while the control arms utilized placebo in combination with letrozole or anastrozole or fulvestrant. The randomization ratio was 2 to 1 in PALOMA-2, PALOMA-3, MONARCH-2 and MONARCH-3 studies and 1 to 1 in PALOMA-1 and MONALEESA-2 trials. CDK 4/6 inhibitors were utilized as first line treatment in PALOMA-1, PALOMA-2, MONALEESA-2 and MONARCH-3. The I2 statistic for heterogeneity was 0, and the heterogeneity X2 (Cochran's Q) was 1 (P= 0.707), suggesting homogeneity among RCTs. The VTE incidence was 25 (3.255%) in the abemaciclib group vs 2 (0.520%) in the control group. The pooled relative risk for VTE was 6.222 (95% CI: 1.481 – 26.145, P = 0.013) and the absolute RD was 0.027 (95% CI: 0.013 – 0.042, P &lt; 0.0001). In other CDK 4/6 inhibitor containing regimens, the VTE incidence was reported at 15 (1.243%) vs 2 (0.374%) in the control arm. The pooled RR for VTE was 2.312 (95% CI: 0.852 –6.272, P = 0.100) and the absolute RD was 0.008 (95% CI: - 0.000 – 0.017, P = 0.259).

Conclusion: VTE is a major cause of morbidity and mortality and is particularly common in patients with breast cancer. Our meta-analysis demonstrated that the addition of abemaciclib to endocrine therapy notably contributed to a higher incidence of VTE with a relative risk of 6.22. However, no significant increase in the risk of VTE was noted in other CDK 4/6 inhibitor-based regimen. More randomized trials are required to determine the actual relation and definitive incidence of VTE among different CDK-targeted agents when added to endocrine therapy.

Citation Format: Thein KZ, Ball S, Zaw MH, Quirch M, Hardwicke F, Awasthi S, Oo TH, Jones C. Risk of venous thromboembolism with abemaciclib based regimen versus other CDK 4/6 inhibitor containing regimens in patients with hormone receptor-positive HER2-negative metastatic breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-16-04.

Copper deficiency anemia: review article

Copper is a crucial micronutrient needed by animals and humans for proper organ function and metabolic processes such as hemoglobin synthesis, as a neurotransmitter, for iron oxidation, cellular respiration, and antioxidant defense peptide amidation, and in the formation of pigments and connective tissue. Multiple factors, either hereditary or acquired, contribute to the increase in copper deficiency seen clinically over the past decades. The uptake of dietary copper into intestinal cells is via the Ctr1 transporter, located at the apical membrane aspect of intestinal cells and in most tissues. Copper is excreted from enterocytes into the blood via the Cu-ATPase, ATP7A, by trafficking the transporter towards the basolateral membrane. Zinc is another important micronutrient in animals and humans. Although zinc absorption may occur by direct interaction with the Ctr1 transporter, its absorption is slightly different. Copper deficiency affects physiologic systems such as bone marrow hematopoiesis, optic nerve function, and the nervous system in general. Detailed pathophysiology and its related diseases are explained in this manuscript. Diagnosis is made by measuring serum copper, serum ceruloplasmin, and 24-h urine copper levels. Copper deficiency anemia is treated with oral or intravenous copper replacement in the form of copper gluconate, copper sulfate, or copper chloride. Hematological manifestations are fully reversible with copper supplementation over a 4- to 12-week period. However, neurological manifestations are only partially reversible with copper supplementation.

Mushroom Poisoning Mimicking Painless Progressive Jaundice: A Case Report with Review of the Literature

Mushroom poisoning is common in the United States. The severity of mushroom poisoning may vary, depending on the geographic location, the amount of toxin delivered, and the genetic characteristics of the mushroom. Though they could have varied presentation, early identification with careful history could be helpful in triage. We present a case of a 69-year-old female of false morel mushroom poisoning leading to hepatotoxicity with painless jaundice and biochemical pancreatitis.

Abstract P1-17-08: Efficacy of lapatinib and capecitabine combination therapy in brain metastases from HER-2 positive metastatic breast cancer: A systematic review and meta- analysis

Background:

Brain metastases contribute to significant morbidity and mortality in breast cancer. Approximately one fourth of breast tumors overexpress the human epidermal growth factor receptor 2 (HER2) protein and are twice as likely to develop brain metastases. There are currently no systemic therapies approved. We undertook a systematic review and pooled analysis of trials to determine the efficacy of lapatinib and capecitabine combination therapy in brain metastases from HER-2 positive metastatic breast cancer (MBC).

Methods:

We performed a comprehensive literature search using MEDLINE, EMBASE databases, and meeting abstracts through December 31, 2016. Trials that utilized lapatinib and capecitabine combination therapy in brain metastases from HER-2 positive MBC were incorporated in the analysis. The pooled estimated rates were calculated using random effects model. Heterogeneity was assessed using I2 statistic.

Results:

A total of 513 patients with brain metastases from HER-2 positive MBC from 6 trials and a subgroup of another 4 trials were included in our analysis. Lapatinib and capecitabine therapy was used as second-line treatment in 9 studies (n= 468) and as first-line treatment in the LANDSCAPE study (n= 45). Three studies were retrospective evaluations of randomized trials and the rest were phase 2 trials. CNS objective response rate (ORR) was 26% (95% CI: 19 – 33, I2: 65.9%). Complete response (CR) rate was 1% (95% CI: 0 - 2, I2: 0.0%) and partial response (PR) rate was noted at 24% (95% CI: 17- 31, I2: 66.1%). Stable disease (SD) occurred in 37% (95% CI: 29- 45, I2: 66.6%) and progressive disease (PD) in 19% (95% CI: 12- 25, I2: 66.5%). The first line LANDSCAPE study had the highest PR (49%) and ORR (53%) without a significant impact on CR rate; PD was 7%.

Conclusion:

Brain metastases in breast cancer is an area of urgent unmet need. Our meta-analysis showed that lapatinib/capecitabine therapy had some first line or second line activity in brain metastases from HER-2 positive MBC. Nevertheless, further randomized controlled trials are required in this patient population.

Citation Format: Thein KZ, Zaw MH, Yendala R, Igid HP, Chai-Adisaksopha C, Hardwicke F, Awasthi S, Radhi S. Efficacy of lapatinib and capecitabine combination therapy in brain metastases from HER-2 positive metastatic breast cancer: A systematic review and meta- analysis [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-17-08.

Abstract P3-14-02: Incidence of venous thromboembolism in patients with hormone receptor-positive HER2-negative metastatic breast cancer treated with CDK 4/6 inhibitors: A systematic review and meta- analysis of randomized controlled trials

Background:

The cyclin dependent kinases (CDK) along with their partners, the cyclins, have a crucial role in regulation of the cell cycle. Several CDK-targeted agents have been employed in hormone receptor positive metastatic breast cancer (MBC) with noteworthy safety concerns. Nevertheless, the impact of this agent on risk of venous thromboembolism (VTE) remains uncertain. We performed a systematic review and meta-analysis of randomized controlled trials (RCT) to determine the risk of VTE among patients with hormone receptor-positive HER2-negative MBC treated with CDK 4/6 inhibitors.

Methods:

We systematically conducted a comprehensive literature search using MEDLINE, EMBASE databases and meeting abstracts through June 2017. Trials that mention deep vein thrombosis and pulmonary embolism as adverse effects were incorporated in the analysis. The primary meta- analytic approach was a fixed effects model using the Mantel-Haenszel (MH) method. It was used to calculate the estimated pooled risk ratio (RR), and risk difference (RD) with 95% confidence interval (CI). Pooled VTE rates were estimated as follows: we multiplied the median follow-up duration by the sample size. Crude study-specific VTE rates were then calculated by dividing the number of incident VTE cases by the total number of person-months follow-up.

Results:

A total of 2671 patients with hormone receptor-positive HER2-negative MBC from four phase 3 studies and one phase 2 study were eligible for analysis. The study arm used palbociclib-letrozole, palbociclib-fulvestrant, ribociclib-letrozole and abemaciclib-fulvestrant while the control arm utilized placebo in combination with letrozole or fulvestrant. The I2 statistic for heterogeneity was 13.6, and the heterogeneity X2 (Cochran's Q) was 4.6 (P= 0.3), suggesting homogeneity of results among the randomized trials. The VTE incidence was 24 (1.46%) in CDK 4/6 group vs 4 (0.39%) in control group. The pooled RR for VTE was 2.736 (95% CI: 1.115 – 6.714, P = 0.028) and the absolute RD was 0.010 (95% CI: 0.002 – 0.018, P = 0.010) according to the fixed effects model. By the random effects model, the pooled RR was 2.411 (95% CI: 0.809 – 7.181, P = 0.114) and RD was 0.009 (95% CI: 0.0 – 0.019, P = 0.048). Over median follow up of 36 months, the RR for VTE was 3.792 (95% CI: 1.838 – 7.822, P &lt; 0.0001) and RD was 0.024 (95% CI: 0.014 – 0.034, P &lt; 0.0001) with the fixed effects model. By the random effects model, the pooled RR for VTE was 4.248 (95% CI: 0.952- 18.959, P = 0.058) and RD was 0.026 (95% CI: 0.004 – 0.021, P &lt; 0.0001). The pooled rate of VTE among CDK 4/6 group was 2.99 per person years compared to 0.50 per person years among control arm.

Conclusion:

Approximately 1% of patients on letrozole or fulvestrant alone developed VTE in previous studies. Our meta-analysis demonstrated that the addition of CDK 4/6 inhibitors to letrozole or fulvestrant, contribute to higher incidence of VTE. More randomized trials are required to determine the actual relation and definitive incidence of VTE, a major cause of morbidity and mortality among these patients.

Citation Format: Thein KZ, Zaw MH, Tun AM, Jones C, Radhi S, Hardwicke F, Oo TH. Incidence of venous thromboembolism in patients with hormone receptor-positive HER2-negative metastatic breast cancer treated with CDK 4/6 inhibitors: A systematic review and meta- analysis of randomized controlled trials [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-14-02.