PSPC1 Inhibition Synergizes with Poly(ADP-ribose) Polymerase Inhibitors in a Preclinical Model of BRCA-Mutated Breast/Ovarian Cancer.

Poly (ADP-ribose) polymerase (PARP) inhibitors are effective against BRCA1/2-mutated cancers through synthetic lethality. Unfortunately, most cases ultimately develop acquired resistance. Therefore, enhancing PARP inhibitor sensitivity and preventing resistance in those cells are an unmet clinical need. Here, we investigated the ability of paraspeckle component 1 (PSPC1), as an additional synthetic lethal partner with BRCA1/2, to enhance olaparib sensitivity in preclinical models of BRCA1/2-mutated breast and ovarian cancers. In vitro, the combined olaparib and PSPC1 small interfering RNA (siRNA) exhibited synergistic anti-proliferative activity in BRCA1/2-mutated breast and ovarian cancer cells. The combination therapy also demonstrated synergistic tumor inhibition in a xenograft mouse model. Mechanistically, olaparib monotherapy increased the expressions of p-ATM and DNA-PKcs, suggesting the activation of a DNA repair pathway, whereas combining PSPC1 siRNA with olaparib decreased the expressions of p-ATM and DNA-PKcs again. As such, the combination increased the formation of γH2AX foci, indicating stronger DNA double-strand breaks. Subsequently, these DNA-damaged cells escaped G2/M checkpoint activation, as indicated by the suppression of p-cdc25C (Ser216) and p-cdc2 (Tyr15) after combination treatment. Finally, these cells entered mitosis, which induced increased apoptosis. Thus, this proves that PSPC1 inhibition enhances olaparib sensitivity by targeting DNA damage response in our preclinical model. The combination of olaparib and PSPC1 inhibition merits further clinical investigation to enhance PARP inhibitor efficacy.

First-in-human study of IM156, a novel potent biguanide oxidative phosphorylation (OXPHOS) inhibitor, in patients with advanced solid tumors.

Preclinical models suggest anticancer activity of IM156, a novel biguanide mitochondrial protein complex 1 inhibitor of oxidative phosphorylation (OXPHOS). This first-in-human dose-escalation study enrolled patients with refractory advanced solid tumors to determine the maximum tolerated dose (MTD) or recommended phase 2 dose (RP2D). Eligible patients received oral IM156 every other day (QOD) or daily (QD) and were assessed for safety, dose-limiting toxicities (DLTs), pharmacokinetics, and preliminary signals of efficacy. 22 patients with advanced cancers (gastric, n = 8; colorectal, n = 3; ovarian, n = 3; other, n = 8) received IM156 100 to 1,200 mg either QOD or QD. There were no DLTs. However, 1,200 mg QD was not well tolerated due to nausea; 800 mg QD was determined as the RP2D. The most frequent treatment-related AEs (TRAEs) were nausea (n = 15; 68%), diarrhea (n = 10; 46%), emesis (n = 9; 41%), fatigue (n = 4; 18%) and abdominal pain, constipation, and blood lactate increased (n = 2 each; 9%). Grade 3 nausea (n = 3; 14%) was the only grade ≥ 3 TRAE. Plasma exposures increased dose proportionally; mean Day 27 area under the curve (AUC0-24) values were higher following QD administration compared to the respective QOD regimen. Stable disease (SD), observed in 7 (32%) patients (confirmed in 2 [9%]), was the best response. To our knowledge, this is the first phase 1 study of an OXPHOS inhibitor that established a RP2D for further clinical development in cancer. Observed AEs of IM156 were manageable and SD was the best response.

Synergism of AZD6738, an ATR Inhibitor, in Combination with Belotecan, a Camptothecin Analogue, in Chemotherapy-Resistant Ovarian Cancer.

Epithelial ovarian cancer remains the leading cause of mortality among all gynecologic malignancies owing to recurrence and ultimate development of chemotherapy resistance in the majority of patients. In the chemotherapy-resistant ovarian cancer preclinical model, we investigated whether AZD6738 (an ataxia telangiectasia and Rad3-related (ATR) inhibitor) could synergize with belotecan (a camptothecin analog and topoisomerase I inhibitor). In vitro, both chemotherapy-resistant and chemotherapy-sensitive ovarian cancer cell lines showed synergistic anti-proliferative activity with a combination treatment of belotecan and AZD6738. The combination also demonstrated synergistic tumor inhibition in mice with a chemotherapy-resistant cell line xenograft. Mechanistically, belotecan, a DNA-damaging agent, increased phospho-ATR (pATR) and phospho-Chk1 (pChk1) in consecutive order, indicating the activation of the DNA repair system. This consequently induced G2/M arrest in the cell cycle analysis. However, when AZD6738 was added to belotecan, pATR and pChk1 induced by belotecan alone were suppressed again. A cell cycle analysis in betotecan showed a sub-G1 increase as well as a G2/M decrease, representing the release of G2/M arrest and the induction of apoptosis. In ascites-derived primary cancer cells from both chemotherapy-sensitive and -resistant ovarian cancer patients, this combination was also synergistic, providing further support for our hypothesis. The combined administration of ATR inhibitor and belotecan proved to be synergistic in our preclinical model. This combination warrants further investigation in a clinical trial, with a particular aim of overcoming chemotherapy resistance in ovarian cancer.

Molecular mechanisms of resistance to CDK4/6 inhibitors in breast cancer: A review.

Deregulation of the cyclin D-CDK4/6-INK4-RB pathway leading to uncontrolled cell proliferation, is frequently observed in breast cancer. Currently, three selective CDK4/6 inhibitors have been FDA approved: palbociclib, ribociclib and abemaciclib. Despite promising clinical outcomes, intrinsic or acquired resistance to CDK4/6 inhibitors has limited the success of these treatments; therefore, the development of various strategies to overcome this resistance is of great importance. We highlight the various mechanisms that are directly or indirectly responsible for resistance to CDK4/6 inhibitors, categorizing them into two broad groups; cell cycle-specific mechanisms and cell cycle-nonspecific mechanisms. Elucidation of the diverse mechanisms through which resistance to CDK4/6 inhibitors occurs, may aid in the design of novel therapeutic strategies to improve patient outcomes. This review summarizes the currently available knowledge regarding mechanisms of resistance to CDK4/6 inhibitors, and possible therapeutic strategies that may overcome this resistance as well.

A novel PI3K/mTOR dual inhibitor, CMG002, overcomes the chemoresistance in ovarian cancer.

OBJECTIVE: Ovarian cancer is the leading cause of gynecologic-related mortality worldwide. Despite successful initial treatment, overall survival rates are very low because tumors develop resistance to chemotherapeutic drugs. The PI3K/mTOR pathway is a key signaling pathway involved in drug resistance of ovarian cancer cells. The aim of this study was to examine the effect of a newly developed PI3K/mTOR dual inhibitor, CMG002, on chemoresistant ovarian cancer cells. METHODS: We examined the effects of CMG002, and its synergistic effects when combined with paclitaxel or cisplatin, on cell viability, cell cycle arrest, and apoptosis of PTX-resistant SKpac17 or cisplatin-resistant A2780cis ovarian cancer cells in vitro. Western blot analysis was performed to assess expression of PI3K, p-mTOR, p-Akt, p-S6, Bim, and caspase-3. In vivo studies were carried out in a xenograft mouse model, followed by TUNEL and immunohistochemical staining of excised tumor tissue. RESULTS: CMG002 showed marked toxicity against chemoresistant ovarian cancer cells and re-sensitized these cells to chemotherapeutic agents by suppressing cell proliferation and inducing G1 cell cycle arrest and apoptosis. In vivo xenograft studies revealed that treatment with CMG002, either alone or in combination with paclitaxel or cisplatin, led to a marked reduction in tumor growth. CMG002 caused marked suppression of mTOR (Ser2448), Akt (Ser473), Akt (Thr308), and S6 (Ser235/236) phosphorylation, both in vitro and in vivo. CONCLUSION: Taken together, CMG002, a very potent PI3K/mTOR dual inhibitor, induced cytotoxicity in chemoresistant ovarian cancer cells, suggesting that this novel inhibitor might be a new therapeutic strategy for chemoresistant ovarian cancer.

Correlation between EGFR gene mutation, cytologic tumor markers, 18F-FDG uptake in non-small cell lung cancer.

BACKGROUND: EGFR mutation-induced cell proliferation causes changes in tumor biology and tumor metabolism, which may reflect tumor marker concentration and 18F-FDG uptake on PET/CT. Direct aspirates of primary lung tumors contain different concentrations of tumor markers than serum tumor markers, and may correlate better with EGFR mutation than serum tumor markers. The purpose of this study is to investigate an association between cytologic tumor markers and FDG uptake with EGFR mutation status in non-small cell lung cancer (NSCLC). METHODS: We prospectively collected tumor aspirates of 61 patients who underwent EGFR mutation analysis. Serum and cytologic CYFRA 21-1, CEA, and SCCA levels were measured and correlated with EGFR gene mutations. FDG PET/CT was performed on 58 patients for NSCLC staging, and SUV was correlated with EGFR mutation status. RESULTS: Thirty (50%) patients had EGFR mutation and 57 patients had adenocarcinoma subtype. Univariate analysis showed that female gender, never smoker, high levels of cytologic CYFRA 21-1 (c-CYFRA) and lower maximum standard uptake value (SUVmax) were correlated with EGFR mutations. ROC generated cut-off values of 20.8 ng/ml for c-CYFRA and SUVmax of 9.6 showed highest sensitivity for EGFR mutation detection. Multivariate analysis revealed that female gender [hazard ratio (HR): 18.15, p = 0.025], higher levels of c-CYFRA (HR: 7.58, and lower SUVmax (HR: 0.08, p = 0.005) were predictive of harboring EGFR mutation. CONCLUSIONS: The cytologic tumor marker c-CYFRA was positively associated with EGFR mutations in NSCLC. EGFR mutation-positive NSCLCs have relatively lower glycolysis compared with NSCLCs without EGFR mutation.

S-1 combined with docetaxel following doxorubicin plus cyclophosphamide as neoadjuvant therapy in breast cancer: phase II trial.

BACKGROUND: This study evaluated the efficacy and safety of S-1 combined with docetaxel (SD) following doxorubicin plus cyclophosphamide (AC) as neoadjuvant therapy in patients with HER2-negative, stage II-III breast cancer. METHODS: Patients received AC every 3 weeks for four cycles followed by S-1 (30 mg/m2 orally b.i.d. on days 1-14) and docetaxel (75 mg/m2 i.v. on day 1) every 3 weeks for four cycles. The primary endpoint was the pathological complete response (pCR) rate in breast and axillary lymph nodes. RESULTS: The study included 49 patients with a median age of 43 years. The median breast tumor size was 4.0 cm by palpation. All patients were positive for involvement of axillary lymph node and five patients also had supraclavicular lymph node metastasis, which was confirmed by histological examination. In total, 85.4% of patients (41/49) completed eight cycles of therapy and 95.9% of patients (47/49) received curative surgery. The pCR rate was 22.5% (n = 11). The clinical response rate was 67.4%. During SD chemotherapy, the most frequent grade 3-4 toxicity was neutropenia (8.5% by cycle). There was a single treatment-related mortality from severe neutropenia. Grade 3 S-1 specific toxicities such as epigastric pain (12.2% by person), stomatitis (4.1% by person), and diarrhea (2.0% by person) were also observed. In particular, gastrointestinal discomfort led to dose reduction of S-1 in 45.8% of patients. CONCLUSIONS: Given all axillary lymph node positive diseases, neoadjuvant S-1 combined with docetaxel following AC showed a favorable anti-tumor activity but gastrointestinal discomfort should be carefully considered for future studies. TRIAL REGISTRATION: NCT00994968.

Preclinical Platform Using a Triple-negative Breast Cancer Syngeneic Murine Model to Evaluate Immune Checkpoint Inhibitors.

BACKGROUND/AIM: To evaluate the feasibility of syngeneic mouse models of breast cancer by analyzing the efficacy of immune checkpoint inhibitors (ICIs) and potential predictive biomarkers. MATERIALS AND METHODS: To establish the murine triple-negative breast cancer (TNBC) models, JC, 4T1, EMT6, and E0771 cells were subcutaneously implanted into female syngeneic mice. When the tumor reached 50-100 mm3, each mouse model was divided into a treatment (using a murine PD-1 antibody) and a no-treatment control group. The treatment group was further divided into the responder and non-responder groups. Potential predictive biomarkers were evaluated by analyzing serum cytokines, peripheral blood T cells and tumor infiltrating immune cells. RESULTS: The EMT6 model showed the highest tumor response rate (54%, 6/11) of the syngeneic models: 4T1 (45%, 5/11), JC (40%, 4/10), or E0771 (23%, 3/13). Early changes in tumor size at 7 days post-PD-1 inhibitor treatment predicted the final efficacy of the PD-1 inhibitor. Peripheral blood CD8+ and CD4+ T cells with or without Ki67 expression at 7 days post-PD-1 inhibitor treatment were higher in the finally designated responder group than in the non-responder group. At the time of sacrifice, analyses of tumor infiltrating lymphocytes consistently supported these results. We also demonstrated that retro-orbital blood sampling procedures (baseline, 7 days post-treatment, time of sacrifice) were safe for serum cytokine analyses, suggesting that our preclinical platform may be used for biomarker research using serum cytokines. CONCLUSION: Our syngeneic mouse model of TNBC is a feasible preclinical platform to evaluate ICI efficacy combined with other drugs and predictive biomarkers in the screening process of immune-oncology drug development.

Combined PI3K Inhibitor and Eribulin Enhances Anti-Tumor Activity in Preclinical Models of Paclitaxel-Resistant, PIK3CA-Mutated Endometrial Cancer.

Endometrial cancer stands as the predominant gynecological malignancy in developed nations. For advanced or recurrent disease, paclitaxel-based chemotherapy is the standard front-line therapy. However, paclitaxel resistance eternally develops. Based on the high prevalence of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) mutation, reaching 50%, in endometrial cancer, we preclinically investigated the effectiveness of a combination of a phosphatidylinositol 3-kinase (PI3K) inhibitor with eribulin, a post-paclitaxel therapy for breast cancer, in treating paclitaxel-resistant, PIK3CA-mutated endometrial cancer. We generated paclitaxel-resistant cell lines from PIK3CA-mutated endometrial cancer cell lines by gradually increasing the concentration of paclitaxel in cell cultures. We observed that the PI3K/AKT and epithelial-mesenchymal transition (EMT) pathways in paclitaxel-resistant cells were significantly upregulated compared with those in parental cells. Then, we demonstrated that the combination of alpelisib (a PI3K inhibitor) and eribulin more effectively suppressed the cellular growth of paclitaxel-resistant cells in in vitro and in vivo xenograft models. Mechanistically, we demonstrated that the effect of the combination could be enhanced by inhibiting both the PI3K/AKT and EMT pathways. Therefore, we suggest that paclitaxel resistance is associated with the activation of the PIK3/AKT pathway in PIK3CA-mutated endometrial cancer, and the combination of a PI3K inhibitor and eribulin merits further clinical investigation.

Targeting PEG10 as a novel therapeutic approach to overcome CDK4/6 inhibitor resistance in breast cancer.

BACKGROUND: Breast cancer is the global leading cancer burden in women and the hormone receptor-positive (HR+) subtype is a major part of breast cancer. Though cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors are highly effective therapy for HR+ subtype, acquired resistance is inevitable in most cases. Herein, we investigated the paternally expressed gene 10 (PEG10)-associated mechanism of acquired resistance to CDK4/6 inhibitors. METHODS: Palbociclib-resistant cells were generated by exposing human HR+ breast cancer cell lines to palbociclib for 7-9 months. In vitro mechanistic study and in vivo xenograft assay were performed. For clinical relevance, public mRNA microarray data sets of early breast cancer were analyzed and PEG10 immunohistochemical staining was performed using pre-CDK4/6 inhibitor tumor samples. RESULTS: We observed that PEG10 was significantly upregulated in palbociclib-resistant cells. Ectopic overexpression of PEG10 in parental cells caused CDK4/6 inhibitor resistance and enhanced epithelial-mesenchymal transition (EMT). On the contrary, PEG10-targeting siRNA or antisense oligonucleotides (ASOs) combined with palbociclib synergistically inhibited proliferation of palbociclib-resistant cells and growth of palbociclib-resistant xenograft in mice and suppressed EMT as well. The mechanistic study confirmed that high PEG10 expression suppressed p21, a natural CDK inhibitor, and SIAH1, a post-translational degrader of ZEB1, augmenting CDK4/6 inhibitor resistance. Then PEG10 siRNA combined with palbociclib suppressed cell cycle progression and EMT via activating p21 and SIAH1, respectively. Consequently, combined PEG10 inhibition and palbociclib overcame CDK4/6 inhibitor resistance. Furthermore, high PEG10 expression was significantly associated with a shorter recurrence-free survival (RFS) based on public mRNA expression data. In pre-CDK4/6 inhibitor treatment tissues, PEG10 positivity by IHC also showed a trend toward a shorter progression-free survival (PFS) with CDK4/6 inhibitor. These results support clinical relevance of PEG10 as a therapeutic target. CONCLUSIONS: We demonstrated a novel PEG10-associated mechanism of CDK4/6 inhibitor resistance. We propose PEG10 as a promising therapeutic target for overcoming PEG10-associated resistance to CDK4/6 inhibitors.

Eflapegrastim versus Pegfilgrastim for Chemotherapy-Induced Neutropenia in Korean and Asian Patients with Early Breast Cancer: Results from the Two Phase III ADVANCE and RECOVER Studies.

PURPOSE: We investigated the consistent efficacy and safety of eflapegrastim, a novel long-acting granulocyte-colony stimulating factor (G-CSF), in Koreans and Asians compared with the pooled population of two global phase 3 trials. Materials and Methods: Two phase 3 trials (ADVANCE and RECOVER) evaluated the efficacy and safety of fixed-dose eflapegrastim (13.2 mg/0.6 mL [3.6 mg G-CSF equivalent]) compared to pegfilgrastim (6 mg based on G-CSF) in breast cancer patients who received neoadjuvant or adjuvant docetaxel/cyclophosphamide. The primary objective was to demonstrate non-inferiority of eflapegrastim compared to pegfilgrastim in mean duration of severe neutropenia (DSN) in cycle 1, in Korean and Asian subpopulations. RESULTS: Among a total of 643 patients randomized to eflapegrastim (n=314) or pegfilgrastim (n=329), 54 Asians (29 to eflapegrastim and 25 to pegfilgrastim) including 28 Koreans (14 to both eflapegrastim and pegfilgrastim) were enrolled. The primary endpoint, DSN in cycle 1 in the eflapegrastim arm was non-inferior to the pegfilgrastim arm in Koreans and Asians. The DSN difference between the eflapegrastim and pegfilgrastim arms was consistent across populations: -0.120 days (95% confidence interval [CI], -0.227 to -0.016), -0.288 (95% CI, -0.714 to 0.143), and -0.267 (95% CI, -0.697 to 0.110) for pooled population, Koreans and Asians, respectively. There were few treatment-related adverse events that caused discontinuation of eflapegrastim (1.9%) or pegfilgrastim (1.5%) in total and no notable trends or differences across patient populations. CONCLUSION: This study may suggest that eflapegrastim showed non-inferior efficacy and similar safety compared to pegfilgrastim in Koreans and Asians, consistently with those of pooled population.

: A case report of re-challenge of immune checkpoint inhibitors after immune-related neurological adverse events: Review of literature.

INTRODUCTION: The indications for immune checkpoint inhibitors (ICIs) are expanding for various cancers because of their durable responses and tolerable safety profiles. Immune-related adverse events (irAEs), including neurological adverse events (nAEs), are associated with ICIs therapy. However, there have been few studies on whether re-challenge with ICIs can be clinically acceptable after neurological AE has improved. PATIENT CONCERNS: A 69-year-old woman with recurrent ovarian cancer undergoing palliative chemotherapy was admitted to our hospital with sudden development of diplopia, dizziness, and gait instability. The patient was administered ICI therapy with anti-angiogenic agents for 9 weeks for 3 cycles. DIAGNOSIS: We performed neurological examination, brain imaging, nerve conduction studies, and serology tests. The patient was diagnosed with Guillain-Barré syndrome variant, an immune-mediated polyneuropathy characterized by a triad of ataxia, areflexia, and ophthalmoplegia. INTERVENTION: After prompt discontinuation of pembrolizumab, the patient was taken intravenous methylprednisolone (2 mg/kg) was administered for 5 days, and her symptoms were partially resolved. With the addition of immunoglobulin 0.4 g/kg for 5 days, her symptoms gradually improved. OUTCOMES: The patient's neurological symptoms improved after immunosuppressive therapy, without sequelae. The NCV showed normal nerve conduction. Unfortunately, because there was little evidence for pembrolizumab rechallenge, pembrolizumab therapy was permanently discontinued, and the tumors eventually progressed.

Combination of Abemaciclib following Eribulin Overcomes Palbociclib-Resistant Breast Cancer by Inhibiting the G2/M Cell Cycle Phase.

Breast cancer remains a leading cancer burden among women worldwide. Acquired resistance of cyclin-dependent kinase (CDK) 4/6 inhibitors occurs in almost all hormone receptor (HR)-positive subtype cases, comprising 70% of breast cancers, although CDK4/6 inhibitors combined with endocrine therapy are highly effective. CDK4/6 inhibitors are not expected to cooperate with cytotoxic chemotherapy based on the basic cytotoxic chemotherapy mode of action that inhibits rapidly proliferating cells. The palbociclib-resistant preclinical model developed in the current study investigated whether the combination of abemaciclib, CDK4/6 inhibitor with eribulin, an antimitotic chemotherapy could be a strategy to overcome palbociclib-resistant HR-positive breast cancer. The current study demonstrated that sequential abemaciclib treatment following eribulin synergistically suppressed CDK4/6 inhibitor-resistant cells by inhibiting the G2/M cell cycle phase more effectively. The current study showed the significant association of the pole-like kinase 1 (PLK1) level and palbociclib resistance. Moreover, the cumulative PLK1 inhibition in the G2/M phase by each eribulin or abemaciclib proved to be a mechanism of the synergistic effect. The synergistic antitumor effect was also supported by in vivo study. The sequential combination of abemaciclib following eribulin merits further clinical trials to overcome resistance to CDK4/6 inhibitors in HR-positive breast cancer.

Ex vivo expanded allogeneic natural killer cells have potent cytolytic activity against cancer cells through different receptor-ligand interactions.

BACKGROUND: Recently, allogeneic natural killer (NK) cells have gained considerable attention as promising immunotherapeutic tools due to their unique biological functions and characteristics. Although many NK expansion strategies have been reported previously, a deeper understanding of cryopreserved allogeneic NK cells is needed for specific therapeutic approaches. METHODS: We isolated CD3-CD56+ primary natural killer (pNK) cells from healthy donors and expanded them ex vivo using a GMP-compliant method without any feeder to generate large volumes of therapeutic pNK cells and cryopreserved stocks. After validation for high purity and activating phenotypes, we performed RNA sequencing of the expanded and cryopreserved pNK cells. The pNK cells were used against various cancer cell lines in 7-AAD/CFSE cytotoxicity assay. For in vivo efficacy study, NSG mice bearing subcutaneous cisplatin-resistant A2780cis xenografts were treated with our pNK cells or cisplatin. Antitumor efficacy was assessed by measuring tumor volume and weight. RESULTS: Compared to the pNK cells before expansion, pNK cells after expansion showed 2855 upregulated genes, including genes related to NK cell activation, cytotoxicity, chemokines, anti-apoptosis, and proliferation. Additionally, the pNK cells showed potent cytolytic activity against various cancer cell lines. Interestingly, our activated pNK cells showed a marked increase in NKp44 (1064-fold), CD40L (12,018-fold), and CCR5 (49-fold), and did not express the programmed cell death protein 1(PD-1). We also demonstrated the in vitro and in vivo efficacies of pNK cells against cisplatin-resistant A2780cis ovarian cancer cells having a high programmed death-ligand 1(PD-L1) and low HLA-C expression. CONCLUSIONS: Taken together, our study provides the first comprehensive genome wide analysis of ex vivo-expanded cryopreserved pNK cells. It also indicates the potential use of expanded and cryopreserved pNK cells as a highly promising immunotherapy for anti-cancer drug resistant patients.

Deregulated Immune Pathway Associated with Palbociclib Resistance in Preclinical Breast Cancer Models: Integrative Genomics and Transcriptomics.

Recently, cyclin-dependent kinase (CDK) 4/6 inhibitors have been widely used to treat advanced hormone receptor-positive breast cancer. Despite promising clinical outcomes, almost all patients eventually acquire resistance to CDK4/6 inhibitors. Here, we screened genes associated with palbociclib resistance through genomics and transcriptomics in preclinical breast cancer models. Palbociclib-resistant cells were generated by exposing hormone receptor-positive breast cancer cell lines to palbociclib. Whole-exome sequencing (WES) and a mRNA microarray were performed to compare the genomic and transcriptomic landscape between both palbociclib-sensitive and resistant cells. Microarray analysis revealed 651 differentially expressed genes (DEGs), while WES revealed 107 clinically significant mutated genes. Furthermore, pathway analysis of both DEGs and mutated genes revealed immune pathway deregulation in palbociclib-resistant cells. Notably, DEG annotation revealed activation of type I interferon pathway, activation of immune checkpoint inhibitory pathway, and suppression of immune checkpoint stimulatory pathway in palbociclib-resistant cells. Moreover, mutations in NCOR1, MUC4, and MUC16 genes found in palbociclib-resistant cells were annotated to be related to the immune pathway. In conclusion, our genomics and transcriptomics analysis using preclinical model, revealed that deregulated immune pathway is an additional mechanism of CDK4/6 inhibitor resistance besides the activation of cyclin E-CDK2 pathway and loss of RB, etc. Further studies are warranted to evaluate whether immune pathways may be a therapeutic target to overcome CDK4/6 inhibitor resistance.

Phase II study of DHP107 (oral paclitaxel) in the first-line treatment of HER2-negative recurrent or metastatic breast cancer (OPTIMAL study).

BACKGROUND: Standard intravenous (IV) paclitaxel is associated with hypersensitivity/toxicity. Alternative IV formulations have improved tolerability but still require frequent hospital visits and IV infusion. DHP107 is a novel oral formulation of paclitaxel that is approved in South Korea for the treatment of gastric cancer. METHODS: This multicenter, phase II study using a Simon's two-stage design investigated the efficacy and safety of DHP107 200 mg/m2 administered orally twice daily on days 1, 8, and 15 every 4 weeks for the first-line treatment of recurrent or metastatic HER2-negative breast cancer. RESULTS: Thirty-six patients were enrolled and 31 were assessable for efficacy. Patient median age was 57 years (range = 34-81) and 11 (31%) had triple-negative disease. A median of seven cycles (range = 1-28) of DHP107 was administered. Objective response rate was 55% (17 patients), all partial responses, according to the investigator's decision and independent central review (ICR), and 44% (4/9 patients) in those with triple-negative disease. Disease control rate (partial response and stable disease) was 74% (23 patients) according to the investigator's decision and ICR. In the intention-to-treat (ITT) population of all enrolled participants, the objective response rate was 50% (18/36 patients). Median progression-free survival was 8.9 months [95% confidence interval [CI]: 5.2-12.3) and median time to treatment failure was 8.0 months (95% CI: 4.2-10.0). DHP107 had an acceptable toxicity profile. All patients experienced treatment-emergent adverse events; the most common adverse events were decreased neutrophil count (81% all grades and 78% grade ⩾ 3) followed by peripheral sensory neuropathy (61% all grades and 8% grade 3). However, there was no febrile neutropenia or sepsis. CONCLUSION: DHP107 showed promising efficacy and acceptable tolerability in this phase II study and is currently being investigated in the OPTIMAL phase III study (NCT03315364). TRIAL REGISTRATION: This trial was registered with ClinicalTrials.gov identifier: NCT03315364.

The clinical outcome of chemotherapy-induced amenorrhea in premenopausal young patients with breast cancer with long-term follow-up.

BACKGROUND: We investigated the factors that predict chemotherapy-induced amenorrhea (CIA) and the prognostic significance of CIA after long-term follow-up. METHODS: We reviewed data from 241 premenopausal patients with breast cancer who underwent adjuvant CMF or FAC chemotherapy after breast cancer surgery between January 1995 and December 2000. RESULTS: The median follow-up duration was 109.8 (range, 16.6-193.1) months. The age of CIA patients was older than non-CIA patients (median, 44 (range, 28-53) years and 36 (range, 25-49) years, respectively; P < 0.001). The addition of tamoxifen to the chemotherapy increased the incidence of CIA from 48% to 63.6% (P = 0.015). The 10-year disease-free survival (DFS) rate was higher in the CIA group compared with the non-CIA group in hormonal receptor-positive patients (78.4% vs. 67%, respectively; P = 0.022), and the 10-year overall survival (OS) rate also was higher in the CIA group compared with the non-CIA group (90.8% vs. 79.7%, respectively; P = 0.041). CONCLUSIONS: The most important predictors of CIA are age and the addition of tamoxifen to the chemotherapy. CIA is likely to have an influence on DFS and OS in premenopausal patients with breast cancer with a positive hormone receptor, and it might be used as a surrogate marker for effective chemotherapy in these young Asian patients.

A comparison of eflapegrastim to pegfilgrastim in the management of chemotherapy-induced neutropenia in patients with early-stage breast cancer undergoing cytotoxic chemotherapy (RECOVER): A Phase 3 study.

Eflapegrastim (Rolontis® ) is a novel, long-acting hematopoietic growth factor consisting of a recombinant human granulocyte-colony stimulating factor (rhG-CSF) analog conjugated to a human IgG4 Fc fragment via a short polyethylene glycol linker. We report results from a second pivotal, randomized, open-label, Phase 3 study comparing the efficacy and safety of eflapegrastim to pegfilgrastim for reducing the risk of chemotherapy-induced neutropenia. Patients with Stage I to IIIA early-stage breast cancer (ESBC) were randomized 1:1 to fixed-dose eflapegrastim 13.2 mg (3.6 mg G-CSF) or pegfilgrastim (6 mg G-CSF) administered one day after standard docetaxel/cyclophosphamide (TC) therapy for four cycles. The primary objective was to demonstrate noninferiority (NI) of eflapegrastim compared to pegfilgrastim in mean duration of severe neutropenia (DSN; Grade 4) in Cycle 1. A total of 237 eligible patients were randomized 1:1 to receive either eflapegrastim (n = 118) or pegfilgrastim (n = 119). Cycle 1 severe neutropenia was observed in 20.3% (n = 24) of patients receiving eflapegrastim and 23.5% (n = 28) receiving pegfilgrastim. The DSN of eflapegrastim in Cycle 1 was noninferior to pegfilgrastim with a mean difference of -0.074 days (NI P-value < .0001). Noninferiority was maintained throughout the four treatment cycles (P < .0001 in all cycles). Other efficacy endpoints results were comparable between treatment arms, and adverse events, irrespective of causality and grade, were comparable between treatment arms. The results demonstrate noninferior efficacy and comparable safety for eflapegrastim, at a lower G-CSF dose, vs pegfilgrastim. The potential for the increased potency of eflapegrastim to deliver improved clinical benefit warrants further clinical study.

Real-World Experience with Pembrolizumab Treatment in Patients with Heavily Treated Recurrent Gynecologic Malignancies.

PURPOSE: We evaluated the efficacy and safety of pembrolizumab in patients with recurrent gynecologic cancers in real-world practice. MATERIALS AND METHODS: We conducted a retrospective, single-institution study of patients with recurrent gynecologic malignancies treated with pembrolizumab. The primary endpoints were the objective response rate (ORR) and safety. RESULTS: Thirty-one patients treated with pembrolizumab were included. The primary disease sites were the uterine cervix (n=18), ovaries (n=8), and uterine corpus (n=5). Fifteen of the 31 patients (48%) had an Eastern Cooperative Oncology Group performance status of ≥2. The median number of prior chemotherapy lines was 2 (range, 1-6), and 14 of 31 patients (45%) had received ≥ 3 prior lines of chemotherapy. The overall ORR was 22.6%: specifically, 22.3% (4 of 18 patients), 12.5% (1 of 8 patients), and 40% (2 of 5 patients) for cervical, ovarian, and endometrial cancers, respectively. During a median follow-up of 4.7 months (range, 0.2-35.3), the median time to response was 1.9 months (range, 1.4-5.7). The median duration of response was not reached (range, 8.8-not reached). The median progression-free survival was 2.5 months (95% confidence interval, 1.7-not reached). Adverse events occurred in 20 patients (64.5%), and only 3 (9.7%) were grade ≥3. There was one case of suspicious treatment-related mortality, apart from which most adverse events were manageable. CONCLUSION: In real-world practice, pembrolizumab was feasible and effective in heavily treated recurrent gynecologic cancer patients with poor performance status who may not be eligible for enrollment in clinical trials.

Combined CDK2 and CDK4/6 Inhibition Overcomes Palbociclib Resistance in Breast Cancer by Enhancing Senescence.

Breast cancer represents the number one global cancer burden in women and the hormone receptor (HR)-positive subtype comprises approximately 70% of breast cancers. Unfortunately, acquired resistance ultimately occurs in almost all cases, even though cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors are a highly effective therapy for HR-positive/human epidermal growth factor receptor 2-negative subtype. Here, we investigated mechanisms of resistance to CDK4/6 inhibitor and potential therapeutic strategies using our palbociclib-resistant preclinical model. We observed that cyclin E was significantly overexpressed in palbociclib-resistant cells, and similar association was also confirmed in pleural effusion samples collected from HR-positive breast cancer patients. After confirmation of cyclin E-CDK2 interaction by co-immunoprecipitation, we demonstrated CDK2 inhibition combined with palbociclib synergistically suppressed proliferation of palbociclib-resistant cells and growth of palbociclib-resistant xenograft in mice. We also proved that enhancing C-MYC-mediated senescence is a novel mechanism behind the synergism created by targeting both CDK2 and CDK4/6. Furthermore, the clinical relevance of cyclin E as a therapeutic target was supported by significant association between CCNE1 overexpression and poor prognosis based on large-scale public gene expression data sets in HR-positive breast cancer patients. Therefore, we propose cyclin E-CDK2 signaling as a promising therapeutic target for overcoming cyclin E-associated resistance to CDK4/6 inhibitor.