Efficacy of immune-checkpoint inhibitors combined with cytotoxic chemotherapy in advanced or recurrent endometrial cancer: A systematic review and meta-analysis.

BACKGROUND: The combination of immune checkpoint inhibitors (ICIs) and platinum-based chemotherapy has emerged as a highly promising primary option for advanced or recurrent endometrial cancer (EC). The study aimed to evaluate treatment efficacy of ICIs with cytotoxic chemotherapy in EC. METHODS: We conducted a comprehensive review of randomized controlled trials up to November 11, 2023, focusing on immunotherapy combined with chemotherapy versus chemotherapy alone for EC. The primary endpoint was the pooled hazard ratio (HR), which was further analyzed across subgroups based on mismatch repair (MMR) status, race, histology, and programmed death-ligand 1 (PD-L1) status. The protocol was registered in PROSPERO (CRD42023475669). FINDINGS: Four trials with 2335 patients were analyzed. ICIs with chemotherapy significantly prolonged progression-free survival (PFS) (HR, 0.70; 95% CI, 0.62-0.79) and overall survival (OS) (HR, 0.75; 95% CI, 0.63-0.89) compared to chemotherapy alone. Stratification by MMR status showed substantial benefits for dMMR (PFS; HR, 0.33; 95% CI, 0.26-0.43; OS; HR, 0.37; 95% CI, 0.22-0.91) over pMMR cohorts in both PFS and OS. In the subgroup analysis, there was significant PFS advantage in Caucasian (HR, 0.63; 95% CI, 0.54-0.72) over non-Caucasian, in endometrioid histology (HR, 0.66; 95% CI, 0.56-0.78) over non-endometrioid, and in PD-L1 positive (HR, 0.39; 95% CI, 0.19-0.81) over PD-L1 negative population. INTERPRETATION: ICIs combined with platinum-based chemotherapy significantly prolonged PFS and OS in patients with advanced or recurrent EC. Patients with dMMR status, Caucasians, endometrioid histology, and positive PD-L1 status showed significant PFS benefits, emphasizing the need for personalized treatment approaches to improve outcomes.

Erratum: Closing the gap for cervical cancer research in Vietnam: current perspectives and future opportunities: a report from the 5th Gynecologic Cancer InterGroup (GCIG) Cervical Cancer Research Network (CCRN) Education Symposium.

This corrects the article on p. e88 in vol. 34, PMID: 37668081.

Reversal of P-glycoprotein-mediated multidrug resistance by natural N-alkylated indole alkaloid derivatives in KB-ChR-8-5 drug-resistant cancer cells.

Multidrug resistance (MDR) remains a significant challenge in cancer chemotherapy due to the overexpression of ATP-binding cassette drug-efflux transporters, namely P-glycoprotein (P-gp)/ATP-binding cassette subfamily B member 1. In this study, derivatives of N-alkylated monoterpene indole alkaloids such as N-(para-bromobenzyl) (NBBT), N-(para-methylbenzyl) (NMBT), and N-(para-methoxyphenethyl) (NMPT) moieties were investigated for the reversal of P-gp-mediated MDR in drug-resistant KB colchicine-resistant 8-5 (KB-ChR-8-5) cells. Among the three indole alkaloid derivatives, the NBBT exhibited the highest P-gp inhibitory activity in a dose-dependent manner. Further, it significantly decreased P-gp overexpression by inactivating the nuclear translocation of the nuclear factor kappa B p-50 subunit. In the cell survival assay, doxorubicin showed 6.3-fold resistance (FR) in KB-ChR-8-5 cells compared with its parental KB-3-1 cells. However, NBBT significantly reduced doxorubicin FR to 1.7, 1.3, and 0.4 and showed strong synergism with doxorubicin for all the concentrations studied in the drug-resistant cells. Furthermore, NBBT and doxorubicin combination decreased the cellular migration and showed increased apoptotic incidence by downregulating Bcl-2, then activating BAX, caspase 3, and p53. The present findings suggest that NBBT could be a lead candidate for the reversal of P-gp- mediated multidrug resistance in cancer cells.

A Phase I, First-in-Human Study of PRL3-zumab in Advanced, Refractory Solid Tumors and Hematological Malignancies.

BACKGROUND: Phosphatase of regenerating liver-3 (PRL-3) is involved in cellular processes driving metastasis, cell proliferation, invasion, motility and survival. It has been shown to be upregulated and overexpressed in cancer tissue, in contrast to low or no expression in most normal tissue. PRL3-zumab is a first-in-class humanized antibody that specifically binds to PRL-3 oncotarget with high affinity and has been shown to reduce tumor growth and increase survival. OBJECTIVE: In the study, we aimed to determine the safety and efficacy of PRL3-zumab in patients with advanced solid tumors and hematological malignancies. METHODS: We conducted a phase I, first-in-human study in advanced solid tumors and hematological malignancies to investigate the safety, tolerability and efficacy of PRL3-zumab. Response rates were evaluated using the Response Evaluation Criteria in Solid Tumors (RECIST) guideline (version 1.1) for solid tumors. For acute myeloid leukemia (AML) patients, bone marrow response criteria based on the European Leukaemia Network (ELN) 2017 guidelines for AML were used. We also explored the pharmacokinetics and pharmacodynamic relationships of PRL3-zumab in patients. This study was registered with ClinicalTrials.gov: NCT03191682. RESULTS: In the dose-escalation cohort, 11 patients with advanced solid tumors were enrolled into the study. An additional 12 patients with solid tumors and four patients with AML were enrolled in the dose-expansion cohort. Maximum tolerability was not achieved in this study, as there were no dose-limiting toxicities. Potential treatment-emergent adverse events were grade 1 increased stoma output and fatigue and grade 2 vomiting. Best response observed was stable disease in three solid-tumor patients (11.1%). The pharmacokinetics of PRL3-zumab were dose proportional, consistent with an IgG type monoclonal antibody. CONCLUSIONS: PRL3-zumab, a first-in-class humanized antibody, was safe and tolerable in solid tumors and hematological malignancies.

Clinical outcome and prognostic factors for Asian patients in Phase I clinical trials.

BACKGROUND: Patient selection is key in Phase I studies, and prognosis can be difficult to estimate in heavily pre-treated patients. Previous prognostic models like the Royal Marsden Hospital (RMH) score or using the neutrophil-lymphocyte ratio (NLR) have not been validated in current novel therapies nor in the Asian Phase I population. METHODS: We conducted a retrospective review of 414 patients with solid tumours participating in Phase I studies at our centre between October 2013 and December 2020. RESULTS: The RMH model showed poorer prognosis with increasing scores [RMH score 1, HR 1.28 (95% CI: 0.96-1.70); RMH score 2, HR 2.27 (95% CI: 1.62-3.17); RMH score 3, HR 4.14 (95% CI: 2.62-6.53)]. NLR did not improve the AUC of the model. Poorer ECOG status (ECOG 1 vs. 0: HR = 1.59 (95% CI = 1.24-2.04), P < 0.001) and primary tumour site (GI vs. breast cancer: HR = 3.06, 95% CI = 2.16-4.35, P < 0.001) were prognostic. CONCLUSIONS: We developed a NCIS prognostic score with excellent prognostic ability for both short-term and longer-term survival (iAUC: 0.71 [95% CI 0.65-0.76]), and validated the RMH model in the largest Asian study to date.

Targeting the immune microenvironment for ovarian cancer therapy.

Ovarian cancer (OC) is an aggressive malignancy characterized by a complex immunosuppressive tumor microenvironment (TME). Immune checkpoint inhibitors have emerged as a breakthrough in cancer therapy by reactivating the antitumor immune response suppressed by tumor cells. However, in the case of OC, these inhibitors have failed to demonstrate significant improvements in patient outcomes, and existing biomarkers have not yet identified promising subgroups. Consequently, there remains a pressing need to understand the interplay between OC tumor cells and their surrounding microenvironment to develop effective immunotherapeutic approaches. This review aims to provide an overview of the OC TME and explore its potential as a therapeutic strategy. Tumor-infiltrating lymphocytes (TILs) are major actors in OC TME. Evidence has been accumulating regarding the spontaneous TILS response against OC antigens. Activated T-helpers secrete a wide range of inflammatory cytokines with a supportive action on cytotoxic T-cells. Simultaneously, mature B-cells are recruited and play a significant antitumor role through opsonization of target antigens and T-cell recruitment. Macrophages also form an important subset of innate immunity (M1-macrophages) while participating in the immune-stimulation context. Finally, OC has shown to engage a significant natural-killer-cells immune response, exerting direct cytotoxicity without prior sensitization. Despite this initial cytotoxicity, OC cells develop various strategies to induce an immune-tolerant state. To this end, multiple immunosuppressive molecules are secreted to impair cytotoxic cells, recruit regulatory cells, alter antigen presentation, and effectively evade immune response. Consequently, OC TME is predominantly infiltrated by immunosuppressive cells such as FOXP3+ regulatory T-cells, M2-polarized macrophages and myeloid-derived suppressor cells. Despite this strong immunosuppressive state, PD-1/PD-L1 inhibitors have failed to improve outcomes. Beyond PD-1/PD-L1, OC expresses multiple other immune checkpoints that contribute to immune evasion, and each representing potential immune targets. Novel immunotherapies are attempting to overcome the immunosuppressive state and induce specific immune responses using antibodies adoptive cell therapy or vaccines. Overall, the OC TME presents both opportunities and obstacles. Immunotherapeutic approaches continue to show promise, and next-generation inhibitors offer exciting opportunities. However, tailoring therapies to individual immune characteristics will be critical for the success of these treatments.

Intraperitoneal Carboplatin for Ovarian Cancer - A Phase 2/3 Trial.

Intraperitoneal Carboplatin for Ovarian CancerThis trial compared intravenous weekly paclitaxel administered with intraperitoneal or intravenous carboplatin. There was a statistically significant increase in progression-free survival in patients with ovarian cancer treated with intraperitoneal versus intravenous carboplatin and paclitaxel, with no difference in overall survival between groups.

Proportions and incidence of locally advanced cervical cancer: a global systematic literature review.

BACKGROUND: Optimal treatment of cervical cancer is based on disease stage; therefore, an understanding of the global epidemiology of specific stages of locally advanced disease is needed. OBJECTIVE: This systematic literature review was conducted to understand the global and region-specific proportions of patients with cervical cancer with locally advanced disease and to determine the incidence of the locally advanced disease. METHODS: Systematic searches identified observational studies published in English between 2010 and June 10, 2020, reporting the proportion of patients with, and/or incidence of, locally advanced stages of cervical cancer (considered International Federation of Gynecology and Obstetrics (FIGO) IB2-IVA). Any staging criteria were considered as long as the proportion with locally advanced disease was distinguishable. For each study, the proportion of locally advanced disease among the cervical cancer population was estimated. RESULTS: The 40 included studies represented 28 countries in North or South America, Asia, Europe, and Africa. Thirty-eight studies reported the proportion of locally advanced disease among populations with cervical cancer. The estimated median proportion of locally advanced disease among all cervical cancer was 37.0% (range 5.6-97.5%; IQR 25.8-52.1%); estimates were generally lowest in North America and highest in Asia. Estimated proportions of ≥50% were reported in nine studies from Asia, Europe, Brazil, and Morocco; estimates ≤25% were reported in six studies from Asia, United States, Brazil, and South Africa. Locally advanced disease was reported for 44% and 49% of women aged >70 and ≥60 years, and 5-100% of younger women with cervical cancer. A greater proportion of locally advanced disease was reported for Asian American (19%) versus White women (8%) in one United States study. Two of five studies describing the incidence of locally advanced disease reported rates of 2-4/100 000 women among different time frames. CONCLUSION: This review highlights global differences in proportions of locally advanced cervical cancer, including regional variance and disparities according to patient race and age.

Looking beyond carboplatin and paclitaxel for the treatment of advanced/recurrent endometrial cancer.

Endometrial cancer incidence and mortality are rising among all ethnic groups. Carboplatin plus paclitaxel is the established frontline treatment for advanced/recurrent disease; however, subsequent treatment with traditional cytotoxic chemotherapy is challenging. The molecular characterization of endometrial cancer has provided important insights into the biological drivers of carcinogenesis, which has allowed for the development of newer precision immunotherapies and targeted therapies, including pembrolizumab, dostarlimab, and lenvatinib. Until recently, platinum rechallenge was often considered at the time of recurrence, given the lack of other available therapeutic options; however, "platinum sensitivity" in endometrial cancer is subjective and largely based on expert opinion and/or practitioner experience. Small retrospective studies have tried to provide guidance on the utility of platinum rechallenge, but they are limited by variable patient characteristics and small sample sizes. The applicability of these retrospective studies to contemporary clinical practice is difficult in the setting of changing patient demographics, a better understanding of endometrial cancer drivers, and the recent approvals of immune checkpoint inhibitors and the combination of lenvatinib plus pembrolizumab in the second-line setting. The primary focus of this review is to distill the available data regarding platinum-doublet chemotherapy rechallenge and highlight recent pivotal developments in endometrial cancer treatment, as well as future directions.

Comparison of global treatment guidelines for locally advanced cervical cancer to optimize best care practices: A systematic and scoping review.

BACKGROUND: Survival outcomes for cervical cancer differ between countries and world regions. Locally advanced cervical cancer (LACC) is associated with poorer outcomes than early-stage disease. Country-specific variations in diagnostic and treatment recommendations might contribute to differences in LACC outcomes among countries. OBJECTIVE: We compared international and country-specific guidelines for LACC diagnostic imaging and treatment recommendations. METHODS: A systematic literature review and targeted search were used to identify cervical cancer treatment guidelines published between January 1999-August 2021. Guidelines were identified via literature databases, health technology assessment databases, disease-specific websites, and health organization websites. The targeted search included guidelines from countries in regions known to have high cervical cancer prevalence or mortality. Non-English guidelines were translated by native speakers or online translation services. RESULTS: Forty-six guidelines from 31 countries, regions, and international organizations were compared (41/46 using staging criteria, 27 of which used 2009 FIGO). Most guidelines recommended imaging tests for diagnosis and staging. Chest X-ray, intravenous pyelogram, CT, and MRI were commonly recommended for diagnosis and staging while MRI and PET-CT were recommended for the assessment of lymph node status and distant metastases, with a preference for PET-CT over MRI. There was global consensus for cisplatin-based concurrent chemoradiation as primary treatment for stages IIB to IVA, with few exceptions. Treatment recommendations for stages IB2 to IIA2 varied. Most guidelines agreed on adjuvant concurrent chemoradiation after radical hysterectomy when there is a high recurrence risk, and adjuvant radiotherapy when there is an intermediate recurrence risk. Recommendations for other adjuvant and neoadjuvant therapies varied among the guidelines. CONCLUSIONS: Differences among treatment guidelines by LACC stage might be influenced by staging criteria used, resource availability, and prevention program effectiveness. Addressing these areas may unify guidelines and improve global outcomes. Review and update of guidelines will be important as novel LACC therapies become available.

Optimizing treatment selection and sequencing decisions for first-line maintenance therapy of newly diagnosed advanced ovarian cancer.

The incidence and mortality rates of ovarian cancer are increasing globally. Ovarian cancer is diagnosed at an advanced stage in 80% of women. After standard, platinum-based, front-line chemotherapy, poly (ADP-ribose) polymerase (PARP) inhibitors and antiangiogenic agents are successfully employed as maintenance strategies for newly diagnosed, advanced ovarian cancer patients. Landmark clinical studies, including SOLO-1, PAOLA-1, PRIMA, and VELIA, have provided crucial insights on optimizing first-line maintenance treatment using PARP inhibitors. A group of ovarian cancer experts, primarily from low- and middle-income countries, met in September 2019 to discuss new developments for the first-line treatment of ovarian cancer and its implications. Key implications of the evolving clinical data included: (1) olaparib or niraparib maintenance therapy appears to be the preferred choice for patients with BRCA1/2 mutations; hence, BRCA testing is beneficial in identifying these patients; (2) niraparib monotherapy and olaparib in combination with bevacizumab have demonstrated significant benefit in progression-free survival (PFS) in homologous recombination deficiency (HRD)-positive patients; (3) bevacizumab, niraparib alone, or observation can be an alternative for HRD-negative patients; (4) further data is warranted to explore the role of PARP inhibitors in treating HRD-negative, ovarian cancer patients to confirm findings of the exploratory analysis of PRIMA; (5) PARP inhibitors may be beneficial for stage IV ovarian cancer patients with inoperable disease and patients with prior neoadjuvant chemotherapy; and (6) there is an urgent need to increase awareness in both clinicians and patients on BRCA and HRD testing for optimizing treatment decision-making and improving clinical outcomes in newly diagnosed, advanced ovarian cancer patients. In clinical medicine, the limited availability of family history (FH) information and the complexity of FH criteria has hampered the implementation of BRCA testing. Moreover, many cancer patients with BRCA mutations are not tested because they do not meet the criteria for FH. Consequently, BRCA testing in many high income countries, including the US and Australia, is underused and used inappropriately, which has resulted in the loss of valuable opportunities for better cancer management and cancer prevention.

Clinical research in ovarian cancer: consensus recommendations from the Gynecologic Cancer InterGroup.

The Gynecologic Cancer InterGroup (GCIG) sixth Ovarian Cancer Conference on Clinical Research was held virtually in October, 2021, following published consensus guidelines. The goal of the consensus meeting was to achieve harmonisation on the design elements of upcoming trials in ovarian cancer, to select important questions for future study, and to identify unmet needs. All 33 GCIG member groups participated in the development, refinement, and adoption of 20 statements within four topic groups on clinical research in ovarian cancer including first line treatment, recurrent disease, disease subgroups, and future trials. Unanimous consensus was obtained for 14 of 20 statements, with greater than 90% concordance in the remaining six statements. The high acceptance rate following active deliberation among the GCIG groups confirmed that a consensus process could be applied in a virtual setting. Together with detailed categorisation of unmet needs, these consensus statements will promote the harmonisation of international clinical research in ovarian cancer.

A phase 1 study of the safety, pharmacokinetics and pharmacodynamics of escalating doses followed by dose expansion of the selective inhibitor of nuclear export (SINE) selinexor in Asian patients with advanced or metastatic malignancies.

Purpose: This phase 1 study aims to evaluate the tolerability and the recommended phase 2 dose of selinexor in Asian patients with advanced or metastatic malignancies. Experimental Design: A total of 105 patients with advanced malignancies were enrolled from two sites in Singapore (National University Hospital and the National Cancer Centre, Singapore) from 24 February 2014 to 14 January 2019. We investigated four dosing schedules of selinexor in a 3 + 3 dose escalation design with an additional Phase 1b expansion cohort. Adverse events were graded with the NCI Common Terminology Criteria for Adverse Events v 4.03. Pharmacodynamic assessments included nuclear cytoplasmic localization of p27, XPO1 cargo proteins pre and post selinexor dosing and pharmacokinetic assessments were conducted at doses between 40 and 60 mg/m2. Results: In our Asian patient cohort, dosing at 40 mg/m2 given 2 out of 3 weeks, was the most tolerable for our patients. At this dose level, grade 3 adverse events included fatigue (8%), hyponatremia (23%), vomiting (5%), thrombocytopenia (5%), and anaemia (2%). Selinexor had a rapid oral absorption with median Tmax of 2 h and no PK accumulation after multiple doses of tested regimens. Complete responses were seen in two lymphoma patients. Partial responses were noted in three diffuse large B cell lymphomas, one Hodgkin's lymphoma and thymic carcinoma patient, respectively. Conclusion: Selinexor is tolerated by Asian patients at 40 mg/m2 twice a week given 2 out of 3 weeks. A 1-week drug holiday was needed as our patients could not tolerate the current approved continuous dosing regimens because of persistent grade 3 fatigue, anorexia and hyponatremia.

Phase Ib/II Dose Expansion Study of Lenvatinib Combined with Letrozole in Postmenopausal Women with Hormone Receptor-Positive Breast Cancer.

PURPOSE: RET is an estrogen response gene with preclinical studies demonstrating cross-talk between the RET and estrogen receptor (ER) pathways. We investigate the role of lenvatinib, a multikinase inhibitor with potent activity against RET, in patients with metastatic breast cancer. PATIENTS AND METHODS: Patients with advanced ER+/HER2- breast cancer were treated with lenvatinib plus letrozole in a phase Ib/II trial. Primary objectives included safety and recommended phase II dose (RP2D) determination in phase Ib, and objective response rates (ORR) in phase II dose expansion. RESULTS: Sixteen patients were recruited in dose finding, where deescalating doses of lenvatinib from 20 to 14 mg were investigated. Lenvatinib 14 mg plus letrozole 2.5 mg daily was determined as RP2D. Thirty-one patients with 5 median lines of prior therapy in the metastatic setting (range, 0-11) were recruited in dose expansion. In this cohort, ORR was 23.3% [95% confidence interval (CI) 9.9%-42.3%], with median duration of response (DoR) of 6.9 months [interquartile range (IQR) 5.9 to 13.1]. Clinical benefit rate ≥6 months (CBR) was 50.0% (95% CI, 31.3%-68.7%). Similar efficacy was observed in the subgroup of 25 patients who progressed on prior CDK4/6 inhibitor therapy [ORR 20.0% (95% CI, 6.8%-40.7%), median DoR 6.9 months (IQR 5.9-13.1), and CBR 52.0% (95% CI, 31.3%-72.2%)]. Pharmacodynamic studies showed target modulation, with paired tumor biopsies indicating downregulation of RET/pERK and improved vascular normalization index. CONCLUSIONS: Lenvatinib plus letrozole had manageable toxicity, with target engagement and preliminary antitumor activity observed, supporting further assessment in randomized studies.

Integration of immunotherapy into treatment of cervical cancer: Recent data and ongoing trials.

Cervical cancer constitutes a significant health burden for women globally. While most patients with early-stage disease can be cured with radical surgery or chemoradiotherapy, patients with high-risk locally advanced disease or with recurrent/metastatic disease have a poor prognosis with standard treatments. Immunotherapies are a rational treatment for this HPV-driven cancer that commonly expresses programmed cell death ligand-1. Before 2021, pembrolizumab was the only United States Food and Drug Administration-approved immunotherapy in cervical cancer, specifically for the second-line recurrent or metastatic (r/m) setting. In late 2021, the antibody-drug conjugate tisotumab vedotin was approved for second-line r/m cervical cancer and pembrolizumab combined with chemotherapy ± bevacizumab was approved for first-line r/m disease based on results from KEYNOTE-826. Moreover, with at least 2 dozen additional immunotherapy clinical trials in the second-line and first-line r/m setting, as well as in locally advanced disease, the treatment landscape for cervical cancer may eventually encounter a potential paradigm shift. Pivotal trials of immunotherapies for cervical cancer that were recently approved or with the potential for regulatory consideration through 2024 are reviewed. As immunotherapy has the opportunity to establish new standards of care in the treatment of cervical cancers, new biomarkers to identify the ideal patient populations for these therapies may also become important. However, issues with access, affordability, and compliance in low- and middle-income countries are anticipated.

PLK1 inhibition selectively induces apoptosis in ARID1A deficient cells through uncoupling of oxygen consumption from ATP production.

Inhibitors of the mitotic kinase PLK1 yield objective responses in a subset of refractory cancers. However, PLK1 overexpression in cancer does not correlate with drug sensitivity, and the clinical development of PLK1 inhibitors has been hampered by the lack of patient selection marker. Using a high-throughput chemical screen, we discovered that cells deficient for the tumor suppressor ARID1A are highly sensitive to PLK1 inhibition. Interestingly this sensitivity was unrelated to canonical functions of PLK1 in mediating G2/M cell cycle transition. Instead, a whole-genome CRISPR screen revealed PLK1 inhibitor sensitivity in ARID1A deficient cells to be dependent on the mitochondrial translation machinery. We find that ARID1A knock-out (KO) cells have an unusual mitochondrial phenotype with aberrant biogenesis, increased oxygen consumption/expression of oxidative phosphorylation genes, but without increased ATP production. Using expansion microscopy and biochemical fractionation, we see that a subset of PLK1 localizes to the mitochondria in interphase cells. Inhibition of PLK1 in ARID1A KO cells further uncouples oxygen consumption from ATP production, with subsequent membrane depolarization and apoptosis. Knockdown of specific subunits of the mitochondrial ribosome reverses PLK1-inhibitor induced apoptosis in ARID1A deficient cells, confirming specificity of the phenotype. Together, these findings highlight a novel interphase role for PLK1 in maintaining mitochondrial fitness under metabolic stress, and a strategy for therapeutic use of PLK1 inhibitors. To translate these findings, we describe a quantitative microscopy assay for assessment of ARID1A protein loss, which could offer a novel patient selection strategy for the clinical development of PLK1 inhibitors in cancer.

Phase Ib Dose-Finding Study of Varlitinib Combined with Weekly Paclitaxel With or Without Carboplatin ± Trastuzumab in Advanced Solid Tumors.

BACKGROUND: Varlitinib is a highly potent, small-molecule, pan-HER inhibitor targeting HER1, HER2, and HER4. It has demonstrated activity in gastric, biliary tract, and breast cancers. OBJECTIVE: We conducted a phase Ib dose confirmation study to determine safety and early efficacy signals of varlitinib in combination with chemotherapy (paclitaxel ± carboplatin) ± subcutaneous trastuzumab. METHODS: Eligible patients had advanced or metastatic solid tumors. A 3+3 dose de-escalation study design was used and pharmacokinetic analyses of varlitinib and paclitaxel were performed. RESULTS: Thirty-seven patients were enrolled into eight cohorts with median 4 (0-14) prior lines of palliative systemic therapies. Carboplatin area under the curve 1.5 and paclitaxel 80 mg/m2 weekly with varlitinib 500 mg twice daily continuously was de-escalated over four dose levels to 300 mg twice daily intermittently (4 days on, 3 days off) due to dose-limiting toxicities, most commonly neutropenia, febrile neutropenia, and electrolyte disturbances, with the triplet combination deemed intolerable and unable to be developed further. Varlitinib was then combined with paclitaxel alone; the recommended phase II dose of varlitinib was 300 mg twice daily intermittently. The addition of subcutaneous trastuzumab 600 mg was safe with no dose-limiting toxicities. Thirty-one patients were evaluable for response: 35.5% partial response, 41.9% stable disease. Twenty patients had HER2+ metastatic breast cancer with a median of 4 (0-14) treatment lines, 8/20 continued on single-agent varlitinib after completing chemotherapy for a median of 5.1 (range 2.0-13.3) months. A pharmacokinetic analysis showed that plasma exposure of varlitinib was dose dependent. Varlitinib administration did not significantly affect the maximum concentration or area under the curve of paclitaxel. CONCLUSIONS: The recommended phase II dose of varlitinib with paclitaxel is 300 mg twice daily intermittently dosed. This is active in HER2+ metastatic breast cancer. Subcutaneous trastuzumab can be added safely to varlitinib and paclitaxel. This combination is currently being evaluated as neoadjuvant therapy in HER2+ breast cancer (NCT02396108). CLINICAL TRIAL REGISTRATION: NCT02396108, date of registration: 25 March, 2015.