Combination Of Kinase Inhibitors Research Articles

Targeted therapy for metastatic renal cell carcinoma

Targeted therapy for metastatic renal cell carcinoma

Treatment of Advanced Melanoma: Past, Present and Future.

Therapeutic options for treating advanced melanoma are progressing rapidly. Until six years ago, the regimen for treating advanced melanoma mainly comprised cytotoxic agents such as dacarbazine, and type I interferons. Since 2014, anti-programmed cell death 1 (PD1) antibodies have become recognized as anchor drugs for treating advanced melanoma with or without additional combination drugs such as ipilimumab. In addition, v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) kinase inhibitors in combination with mitogen-activated protein kinase kinase (MEK) inhibitors are among the most promising chemotherapeutic regimens for treating advanced BRAF-mutant melanoma, especially in patients with low tumor burden. Since anti-PD1 antibodies are widely applicable for the treatment of both BRAF wild-type and mutated advanced melanomas, several clinical trials for drugs in combination with anti-PD1 antibodies are ongoing. This review focuses on the development of the anti-melanoma therapies available today, and discusses the clinical trials of novel regimens for the treatment of advanced melanoma.

Combining kinase inhibitors for optimally co-targeting cancer and drug escape by exploitation of drug target promiscuities.

Cancers resist targeted therapeutics by drug-escape signaling. Multitarget drugs co-targeting cancer and drug-escape mediators (DEMs) are clinically advantageous. DEM coverage may be expanded by drug combinations. This work evaluated to what extent the kinase DEMs (KDEMs) can be optimally co-targeted by drug combinations based on target promiscuities of individual drugs. We focused on 41 approved and 28 clinical trial small molecule kinase inhibitor drugs with available experimental kinome and clinical pharmacokinetic data. From the kinome inhibitory profiles of these drugs, drug combinations were assembled for optimally co-targeting an established cancer target (EGFR, HER2, ABL1, or MEK1) and 9-16 target-associated KDEMs at comparable potency levels as that against the cancer target. Each set of two-, three-, and four-drug combinations co-target 36-71%, 44-89%, 50-88%, and 27-55% KDEMs of EGFR, HER2, ABL1, and MEK1, respectively, compared with the 36, 33, 38, and 18% KDEMs maximally co-targeted by an existing drug or drug combination approved or clinically tested for the respective cancer. Some co-targeted KDEMs are not covered by any existing drug or drug combination. Our work suggested that novel drug combinations may be constructed for optimally co-targeting cancer and drug escape by the exploitation of drug target promiscuities.

Design and synthesis of novel 2,3-dihydropyrazino[1,2-a]indole-1,4-dione derivatives as antiproliferative EGFR and BRAFV600E dual inhibitors

Recent studies have shown additive and synergistic effects associated with the combination of kinase inhibitors. BRAFV600E and EGFR are attractive targets for many diseases treatments and have been studied extensively. In keeping with our interest in developing anticancer targeting EGFR and BRAFV600E, a novel series of 2,3-dihydropyrazino[1,2-a]indole-1,4-dione has been rationally designed, synthesized and evaluated for their antiproliferative activity against a panel of four human cancer cell lines. Compounds 20–23, 28–31, and 33 showed promising antiproliferative activities. These compounds were further tested for their inhibitory potencies against EGFR and BRAFV600E kinases with erlotinib as a reference drug. Compounds 23 and 33 exhibited equipotency to doxorubicin against the four cell lines and efficiently inhibited both EGFR (IC50 = 0.08 and 0.09 µM, respectively) and BRAFV600E (IC50 = 0.1 and 0.29 µM, respectively). In cell cycle study of MCF-7 cell line, compounds 23 and 33 induced apoptosis and exhibited cell cycle arrest in both Pre-G1 and G2/M phases. Molecular docking analyses revealed that the new compounds can fit snugly into the active sites of EGFR, and BRAFV600E kinases. Compound 23, 31 and 33 adopted similar binding orientations and interactions to those of erlotinib and vemurafenib.

ALL-216: Outcomes of Patients with Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia in Molecular Response at Three Months of Therapy

Context The combination of tyrosine kinase inhibitors (TKI) with intensive chemotherapy improves outcome of patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph-pos ALL), particularly among patients in molecular response within three months of therapy. Objective The aim of this study is to identify prognostic factors for relapse and/or death in patients with Ph-pos ALL after 3 months of therapy. Design Retrospective analysis of patients who enrolled on prospective clinical trials of the combination of hyper-CVAD (HCVAD) with a TKI. Setting MD Anderson Cancer Center. Patients or other participants We analyzed 204 patients with newly diagnosed Ph-pos ALL who were treated with HCVAD with a TKI; imatinib (N=44), dasatinib (N=88), and ponatinib (N=72). Interventions Molecular response was assessed at CR, at 3 months, every 3 months during the first 2 years, and every 3-6 months thereafter. Allogeneic stem cell transplantation was offered at the discretion of patient and treating physician. Ponatinib dose was reduced to 15 mg daily, once CMR is achieved. Main outcome measures Progression -free survival (PFS) was calculated from the date of treatment initiation until date of relapse, or death. Overall survival (OS) was calculated from the time of treatment initiation until death. Results By multivariate analysis for PFS and OS in patients who achieved CMR within 3 months of therapy, ponatinib therapy was the only significant independent factor predicting for progression (P=0.028; hazard ratio [HR], 0.388; 95% confidence interval [CI], 0.166-0.904) and death (P=0.042; HR, 0.379; 95% CI, 0.149-0.966); among patients who did not achieve CMR within 3 months, the achievement of major molecular response was a favorable prognostic factor. Though the number of patients with MMR and without molecular response (i.e., no CMR/MMR) is limited, there was a tendency of improved PFS in patients who received allogeneic stem cell transplant. Conclusions The achievement of CMR within 3 months of therapy is the landmark for long-term survival. Ponatinib maintains CMR, and prevents relapse and death in patients with newly diagnosed Ph-pos ALL. MMR within 3 months was associated with improved survival compared to the lack of MMR within 3 months of TKI therapy.

Second-line tyrosine kinase inhibitor-therapy after immunotherapy-failure.

Most contemporary metastatic renal-cell carcinoma patients receive first-line immunotherapy and tyrosine kinase inhibitor (TKI) combination or immunotherapy-immunotherapy combination, as first-line standards of care. However, second-line therapy choices are less well established. To address this void, we examined existing evidence supporting second and subsequent-line treatment options after immunotherapy-based combination therapy. Evidence regarding efficacy of second-line therapy after immunotherapy-based combination is mainly retrospective, except for axitinib, which is the only TKI with prospective efficacy data in this setting. Cabozantinib demonstrated excellent second-line progression-free survival (PFS) that remained in third or later line use, albeit based on small numbers of observations. Moreover, pazopanib demonstrated excellent PFS, but showed wider variability in PFS rates. Sunitinib's PFS rates appeared lower than for axitinib, cabozantinib or pazopanib. Finally, inhibitors of the mammalian target of rapamycin pathway appeared to offer even lower efficacy than any TKI after immunotherapy-based therapy combinations. All available contemporary evidence about TKI efficacy after immunotherapy-based therapy combinations is based on institutional studies. No major differences in efficacy for the examined TKIs after immunotherapy-based combination therapies were recorded. In general, these showed similar efficacy to their efficacy data recorded in first-line.

Abstract 660: Combination of mTOR kinase inhibitors with Src inhibitors in PTEN-mt prostate cancer cells

Abstract Although Src inhibitors are able to suppress malignant functions, their clinical outcomes are modest for the treatment of advanced prostate cancer, many of which harbor mutated PTEN. mTOR pathway is commonly hyperactivated in prostate cancer due to frequent PTEN mutation, and it is known that two mTOR complexes are both critical in prostate cancer progression. However, the functional role of mTOR kinase in Src inhibitor-mediated response remains unknown. In the current study, we combined mTOR kinase inhibitor AZD8055 and Src inhibitor dasatinib to evaluate functional behaviors in PTEN-deleted prostate cancer cells. Gene silencing was achieved by siRNA or shRNA transfection. Cell proliferation and clonogenic survival were performed by MTT and colony formation assay, respectively. “Wound-healing” scratch assay was conducted to monitor cell migration, and Matrigel-based transwell assay was applied to assess cell invasion. Protein expression was detected by Western blotting. We found that in PTEN-mt cells, C4-2B showed greater expression of p-Akt, p-S6, p-4EBP1 and p-eIF4E, all of which are mTOR complexes downstream components. Such molecular profile is consistent with functional observation that C4-2B cells are more resistant to dasatinib. Interestingly, single knockdown of either 4EBP1, S6RP or AKT showed little effects of inhibiting cell survival, while double knockdown of both 4EBP1 and AKT, cell survival was significantly inhibited. Consistently, two agents together showed significantly greater inhibition on proliferation and clonogenic survival than either single agent. Such combination effects were either additive or synergistic depending on the cell types, as reflected by combination index calculation. In addition, cell migration and invasion were inhibited in a greater extent by AZD8055 plus dasatinib, compared to either treatment alone. At the molecular level, co-targeting mTOR and Src kinases leads to strong inhibition of mTOR and Src pathways, such as FAK, Akt, S6RP and 4E-BP1. These data indicate that adding AZD8055 to dasatinib may achieve better treatment outcomes in PTEN-mt prostate cancer models. Such combination modality hold potential for future development as a novel strategy for PTEN-mutated prostate cancer patients who are less responsive to Src inhibitors. Citation Format: Yao Dai, Dietmar Siemann. Combination of mTOR kinase inhibitors with Src inhibitors in PTEN-mt prostate cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 660.

Abstract 5180: Nuclear receptor tyrosine kinase c-MET restrains efficacy of PARP inhibitor in pancreatic cancer cells

Abstract Pancreatic tumors commonly have intra-tumor hypoxia and high reactive oxygen species (ROS) production and have become the fourth leading cause of death in the United States. Although ROS leads to oxidation of macromolecules such as DNA, protein, and lipids, pancreatic cancer cells are capable of surviving from the ROS-induced stress at relatively high tolerable levels. Therefore, identifying potential molecular mechanisms for pancreatic cancer cells to overcome ROS-induced cellular stress is important for develop therapeutic strategies in treating pancreatic cancer patients. While poly (ADP-ribose) polymerase 1 (PARP1) is a key protein for repairing ROS-induced DNA damages, we intended to include PARP inhibitors in targeted therapy strategy. Recent clinical trial showed that PARP inhibitor benefits pancreatic patients with BRCA mutation. However, our goal is to expand PARP inhibitor targeted therapy to pancreatic cancer patients without BRCA mutation with PARP inhibitor using strategies of combining kinase inhibitors as we demonstrated in breast cancer in our previous publications. Here, we used hydrogen peroxide (H2O2) as ROS stimuli and demonstrated that H2O2 induces nuclear transport of the receptor tyrosine kinase c-MET in AsPC-1 and BxPC-3 pancreatic cancer cells. We further showed that nuclear-located c-MET interacts with PARP1, and the interaction can be partially interrupted by crizotinib, a kinase inhibitor targeting c-MET. Moreover, combination of crizotinib and PARP inhibitor, olaparib, has synergistic anti-tumor effect in eliminating pancreatic cancer cells. Our data suggest that the intra-tumor hypoxia micro-environment of pancreatic cancer may promote nuclear localization of c-MET, which results in resistance to PARP inhibitor therapy. We further proposed a new therapeutic strategy of combining c-MET inhibitors and PARP inhibitors for advanced pancreatic cancer patients. Citation Format: Yuan Gao, Mei-Kuang Chen, Dihua Yu, Mien-Chie Hung. Nuclear receptor tyrosine kinase c-MET restrains efficacy of PARP inhibitor in pancreatic cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5180.

Abstract 1008: Characterizing the post-translational regulation of programmed death-ligand 1 (PD-L1) in triple-negative breast cancer: Role of EphA3/Fes/Fer

Abstract Background: The programmed death ligand-1 (PD-L1) is a cell surface protein expressed on a variety of antigen-presenting cells for the purpose of controlling the immune response. As such, the role of PD-L1 expression on the surface of cancer cells has been proven to contribute to cancer immune evasion and tumor progression. Triple negative breast cancer has the most abundant tumor infiltrating lymphocytes (TILs) and PD-L1 is found highly upregulated in TNBC, allowing blockade immune checkpoint therapy a potentially effective treatment. However, the overall response rate is less than 20-30%. Over the past years, the literature that implicated the regulation of PD-L1 was primarily on transcription levels. The objective of our present study is to further characterize the post-translational modification of PD-L1 in efforts to better target it in TNBC immunotherapy. Methods and Results: By proteomic screen utilizing tandem affinity purification of interacting proteins using SFB (S, Flag, and Streptavidin binding peptide)-tagged PD-L1, we identified a number of novel interactions between PD-L1 and 67 candidates. A number of exclusive kinases have also shown high-confidence binding with PD-L1 in the proteomic screen. The primary hits were shortlisted and validated by means of co-immunoprecipitation (co-IP). The co-IP has confirmed a number of hits identified in the proteomic screen, including receptor tyrosine kinases (ephrin receptors, EphA3), and non-receptor tyrosine kinases (Fes and Fer) which have been explored in tumor progression and immune cell development. To test whether our candidate kinases can directly phosphorylate PD-L1 in vitro, His tagged-PD-L1 was mixed with active EphA3/Fes/Fer kinases. Phosphorylated PD-L1-His was detected by WB using PNBM treatment and anti-thiophosphate antibody. Kinase assays showed that EphA3/Fes/Fer can directly phosphorylate PD-L1. We also found that Fes/Fer were able to up-regulate PD-L1 protein expression in a dose-dependent manner. Conclusions: PD-L1 exhibits interactions with tyrosine kinases, which suggests PD-L1 phosphorylation as a novel post-translational modification. Our findings provide a rationale for the development of combination kinase inhibitors and immunotherapy in TNBC. Citation Format: Min Ling, Wenqi Wang, Xiaolong Yang. Characterizing the post-translational regulation of programmed death-ligand 1 (PD-L1) in triple-negative breast cancer: Role of EphA3/Fes/Fer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1008.

Complete response to immune checkpoint inhibitors-based therapy in advanced renal cell carcinoma patients. A meta-analysis of randomized clinical trials

BackgroundA major breakthrough with immunotherapy is its potential to achieve complete responses (CR) in a subset of advanced renal cell carcinoma (RCC) patients. We aim at evaluating the incidence and relative risk (RR) of CR in RCC patients treated with immune checkpoint inhibitors (ICIs). Materials and methodsSearching the MEDLINE/PubMed, Cochrane Library and ASCO Meeting abstracts prospective studies were identified. The proportion of patients with CR events and the derived 95% confidence intervals (CIs) were calculated for each study. Combined relative risks (RRs) and 95% CIs were calculated using fixed- or random-effects methods. The analysis was performed in the intention to treat population, in the PD-L1 expressing (≥1%) RCC tumors and in patients treated with the combination of ICIs and anti-VEGFR tyrosine kinase inhibitors. ResultsSix articles were considered for final analysis (total of 4.531 patients). The incidence of CR was 6.2% with ICIs and 2.6% with SOC. Treatment with ICIs significantly increased the risk of achieving CR compared to SOC (RR = 2.40; P = 0.001). This data was confirmed for patients treated with the combination of ICIs plus anti-VEGFR tyrosine kinase inhibitors (RR = 2.50; P = 0.002). In PD-L1 positive tumors, the incidence of CR was 10.0% with ICIs and 4.0% in the SOC arm (RR = 2.49; P < 0.0001). ConclusionsICIs provide higher rates of CR compared to SOC, even higher in patients with PD-L1 positive tumors.

Combination of traditional Chinese medicine and epidermal growth factor receptor tyrosine kinase inhibitors in the treatment of non-small cell lung cancer

Background:In China, traditional Chinese medicine (TCM) is an increasingly important part of the treatment of non-small cell lung cancer (NSCLC), which usually includes a combination of prescription and syndrome differentiation. Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have been proven to be the first-line drugs for the treatment of advanced EGFR mutation-positive NSCLC. In China, EGFR-TKIs are used in combination with traditional Chinese medicines to reduce side effects and/or enhance effectiveness. Nevertheless, the relationship between TCMs and EGFR-TKIs remain unclear. This meta-review aimed to explore the clinical evidence of TCMs combined with EGFR-TKIs in the treatment of NSCLC.Methods:Related studies were found by searching the databases of EMBASE, PubMed, Web of Science, MEDLINE, Cochrane library database, China Academic Journals (CNKI), Wanfang and Weipu. This study included 57 randomized controlled trials, all of these were processed by Stata software (version 12.0). In the study, all the materials are published articles, patient anonymity and informed consent and ethics Approval/Institutional review board are not necessary.Results:This study demonstrated that the objective response rate was higher in the group of TCMs plus EGFR-TKIs than in the group of EGFR-TKIs alone (risk ratios 1.39, 95% confidence intervals [1.29, 1.50]). Further research of specific herbal medicines showed that Huangqi, Baishu, Fuling, Gancao, Maidong, Baihuashecao, Shashen, Dangshen and Renshen, had significant higher contributions to results.Conclusion:TCMs may improve the efficacy of EGFR-TKIs in the treatment of NSCLC.

Synergistic drug combinations and machine learning for drug repurposing in chordoma

Chordoma is a devastating rare cancer that affects one in a million people. With a mean-survival of just 6 years and no approved medicines, the primary treatments are surgery and radiation. In order to speed new medicines to chordoma patients, a drug repurposing strategy represents an attractive approach. Drugs that have already advanced through human clinical safety trials have the potential to be approved more quickly than de novo discovered medicines on new targets. We have taken two strategies to enable this: (1) generated and validated machine learning models of chordoma inhibition and screened compounds of interest in vitro. (2) Tested combinations of approved kinase inhibitors already being individually evaluated for chordoma. Several published studies of compounds screened against chordoma cell lines were used to generate Bayesian Machine learning models which were then used to score compounds selected from the NIH NCATS industry-provided assets. Out of these compounds, the mTOR inhibitor AZD2014, was the most potent against chordoma cell lines (IC50 0.35 µM U-CH1 and 0.61 µM U-CH2). Several studies have shown the importance of the mTOR signaling pathway in chordoma and suggest it as a promising avenue for targeted therapy. Additionally, two currently FDA approved drugs, afatinib and palbociclib (EGFR and CDK4/6 inhibitors, respectively) demonstrated synergy in vitro (CI50 = 0.43) while AZD2014 and afatanib also showed synergy (CI50 = 0.41) against a chordoma cell in vitro. These findings may be of interest clinically, and this in vitro- and in silico approach could also be applied to other rare cancers.

Acute interstitial nephritis: New agents for an old entity

A 73-year-old male diagnosed with metastasized malignant melanoma was started on combined therapy with dabrafenib and trametinib, but soon admitted with gastrointestinal intolerance. Blood tests revealed toxic hepatitis and acute kidney injury. Renal duplex Doppler ultrasound ruled out urinary and vascular obstruction and apart from a positive antinuclear antibody, other tests for acute kidney injury assessment were unremarkable. Urinary sediment microscopy showed dysmorphic red blood cells, in addition to yellow-pigmented casts. Kidney biopsy revealed signs of acute tubular necrosis and acute interstitial nephritis. Kidney function declined further, prompting the need for urgent hemodialysis. Treatment with dabrafenib and trametinib was stopped and corticosteroids were initiated, with a rapid beneficial effect on both the kidney function and liver toxicity. Hemodialysis was stopped after four sessions with a full recovery after 2 months of corticosteroids, with the dose being slowly tapered. Unfortunately, the patient died a few months later due to melanoma progression. Dual therapy with the combination of a B-Raf proto-oncogene inhibitor with a mitogen-activated protein kinase kinase inhibitor improves response rates and has been recently approved by the U.S. Food and Drug Administration, and while dermatologic toxicity is a common adverse effect, the association with acute renal failure has seldom been reported. To the best of our knowledge, there are only two published case reports of acute kidney injury in patients treated with combination of dabrafenib and trametinib and only one of them is biopsy proven. Further studies evaluating the incidence of acute kidney injury with the combination of B-Raf proto-oncogene and mitogen-activated protein kinase kinase inhibitors are warranted, and may provide new insights into the mechanisms underlying renal toxicity.

PD1/PD-L1 therapy in metastatic renal cell carcinoma.

The aim of the article to summarize recent changes of treatment options in metastatic renal cell carcinoma (mRCC) with a special emphasis on immune checkpoint inhibition. The introduction of checkpoint inhibitor (CPI) therapy has led to a paradigm change in advanced renal cell carcinoma (RCC). Dual immune checkpoint inhibition or the combination of CPI and tyrosine kinase inhibitors (TKIs) was shown to improve survival when compared with the former standard of care sunitinib. Moreover, these novel strategies were shown to enable unprecedented rates of complete and durable responses, particularly with dual checkpoint inhibition. Although the treatment landscape has rapidly evolved, it remains unknown which combination is the best for the individual patient. Pivotal trials have used sunitinib as a comparator but no head to head comparisons have been conducted between novel agents so far. Moreover, no predictive biomarker has been identified yet to bring the best treatment to the individual patient. The aim of this review is to summarize the findings of CPI-based trials conducted in RCC and to discuss the future of mRCC treatment.

Multidrug resistance protein 4 (MRP4/ABCC4) is overexpressed in clear cell renal cell carcinoma (ccRCC) and is essential to regulate cell proliferation

Kidney cancer accounts for 2.5% of all cancers, with an annual global incidence of almost 300,000 cases leading to 111,000 deaths. Approximately 85% of kidney tumors are renal cell carcinoma (RCC) and their major histologic subtype is clear cell renal cell carcinoma (ccRCC). Although new therapeutic treatments are being designed and applied based on the combination of tyrosine kinase inhibitors and immunotherapy, no major impact on the mortality has been reported so far.MRP4 is a pump efflux that transporters multiple endogenous and exogenous substances. Recently it has been associated with tumoral persistence and cell proliferation in several types of cancer including pancreas, lung, ovary, colon, ostesarcoma, etc.Herein, we demonstrate for the first time, that MRP4 is overexpressed in ccRCC tumors, compared to control renal tissues. In addition, using cell culture models, we observed that MRP4 pharmacological inhibition produces an imbalance in cAMP metabolism, induces cell arrest, changes in lipid composition, increase in cytoplasmic lipid droplets and finally apoptosis.These data provide solid evidence for the future evaluation of MRP4 as a possible new therapeutic target in ccRCC.

Combination of cyclin-dependent kinase and immune checkpoint inhibitors for the treatment of bladder cancer.

Perturbation of the CDK4/6 pathway is frequently observed in advanced bladder cancer. We investigated the potential of targeting this pathway alone or in combination with chemotherapy or immunotherapy as a therapeutic approach for the treatment of bladder cancer METHODS: The genetic alterations of the CDK4/6 pathway in bladder cancer were first analyzed with The Cancer Genome Atlas database and validated in our bladder cancer patient-derived tumor xenografts (PDXs). Bladder cancer cell lines and mice carrying PDXs with the CDK4/6 pathway perturbations were treated with a CDK4/6 inhibitor palbociclib to determine its anticancer activity and the underlying mechanisms. The combination index method was performed to assess palbociclib and gemcitabine drug-drug interactions. Syngeneic mouse bladder cancer model BBN963 was used to assess whether palbociclib could potentiate anti-PD1 immunotherapy. Of the 413 bladder cancer specimens, 79.2% harbored pertubations along the CDK4/6 pathway. Palbociclib induced G0/G1 cell cycle arrest but with minimal apoptosis in vitro. In mice carrying PDXs, palbociclib treatment reduced tumor growth and prolonged survival from 14 to 32days compared to vehicle only controls (p = 0.0001). Palbociclib treatment was associated with a decrease in Rb phosphorylation in both cell lines and PDXs. Palbociclib and gemcitabine exhibited antagonistic cytotoxicity in vitro (CI > 3) and in vivo, but palbociclibsignificantly enhanced the treatment efficacy of anti-PD1 immunotherapy and induced CD8+ T lymphocyte infiltration in syngeneic mouse models. The CDK4/6 pathway is feasible as a potential target for the treatment of bladder cancer, especially in combination with immunotherapy. A CDK4/6 inhibitor should not be combined with gemcitabine.

Increased therapeutic effect on medullary thyroid cancer using a combination of radiation and tyrosine kinase inhibitors.

Since patients with medullary thyroid cancer (MTC) often have metastatic disease at the time of diagnosis, the development of efficient systemic treatment options for MTC is important. Vandetanib and cabozantinib are two tyrosine kinase inhibitors (TKIs) that were recently approved by FDA and EMA for systemic treatment of metastatic MTC. Additionally, since MTC is of a neuroendocrine tumour type, treatment with radiolabelled somatostatin analogues (e.g. 177Lu-octreotate) is a valid option for patients with MTC. The aim of this study was to investigate the potentially increased therapeutic effect of combining radiation therapy with these TKIs for treatment of MTC in a mouse model. Nude mice carrying patient-derived MTC tumours (GOT2) were treated with external beam radiotherapy (EBRT) and/or one of the two TKIs vandetanib or cabozantinib. The tumour volume was determined and compared with that of mock-treated controls. The treatment doses were chosen to give a moderate effect as monotherapy to be able to detect any increased therapeutic effect from the combination therapy. At the end of follow-up, tumours were processed for immunohistochemical (IHC) analyses. The animals in the combination therapy groups showed the largest reduction in tumour volume and the longest time to tumour progression. Two weeks after start of treatment, the tumour volume for these mice was reduced by about 70-75% compared with controls. Furthermore, also EBRT and TKI monotherapy resulted in a clear anti-tumour effect with a reduced tumour growth compared with controls. The results show that an increased therapeutic effect could be achieved when irradiation is combined with TKIs for treatment of MTC. Future studies should evaluate the potential of using 177Lu-octreotate therapy in combination with TKIs in patients.

A retrospective analysis of CDK4/6 inhibitors among adult female patients with metastatic breast cancer.

e13028 Background: The aim of this study is to examine the behavior pattern of cyclin-dependent kinase (CDK4/6) inhibitor combinations in adult females with de novo metastatic breast cancer as first therapy or following adjuvant hormonal therapy. Methods: Using United States open health claims and prescription data we analyzed metastatic breast cancer from 2015 Q1 to 2019 Q4, adult female patients (age ≥18). Patients were classified into 3 groups based on their first therapy: Group 1-Hormonal, Group 2-CDK4/6 Inhibitor Combinations, and Group 3-Everolimus Combination. Analysis was completed using the Chi-Squared goodness of fit test assessing the patients moving to next therapy by time period. We also compared the overall CDK4/6 group as a base for probability distribution to study the pattern of therapy change in individual groups. Results: Of 37,351 patients on CDK4/6 inhibitors as first therapy or following adjuvant hormonal therapy for advanced/metastatic diseases, the percentage of patients who moved to next therapy was 3.2% (1,200 patients). For most patients, change in therapy occurred within a 2-year period (87%) and those who remained on their first therapy continued for an extended duration. In both Groups 1 and 2 no statistically significant difference was found in the treatment pattern compared to the overall CDK4/6 inhibitor patient population. However, most patients in Group 3 (90%) compared to the overall patient population on CDK4/6 inhibitors moved to Chemotherapy within the first year of treatment (statistically significant at p-value = 0.02). Further analysis of granularity in individual patient pathways showed about 90% of patients with CDK4/6 inhibitors remained on therapy for about 1 year and, interestingly, about 2% extended beyond 2 years up to 4.5 years. Conclusions: The results show most patients on CDK4/6 inhibitors (95%) had progression free survival (PFS) for the period we analyzed. Overall, patients on CDK4/6 inhibitors behaved similarly when used as first therapy or following adjuvant hormonal therapy.

Combination therapy with nivolumab and tyrosine kinase inhibitors in patients with metastatic renal cell carcinoma.

e17090 Background: Two immunotherapy (IO) and tyrosine kinase inhibitor (TKI) combinations are FDA-approved for patients (pts) with metastatic renal cell carcinoma (mRCC). Here we present a multicenter off-protocol experience with IO/TKI combinations after progression on monotherapy. Methods: We performed a retrospective analysis of pts with mRCC who received combination non-FDA approved off-protocol IO/TKI combination therapy from 11/2015 – 1/2019 at MD Anderson Cancer Center and Duke Cancer Institute. Results: 48 pts met criteria for study inclusion. At therapy start: median (med) age 65 years; 75% clear cell histology; 68.8% IMDC intermediate risk (20.8% favorable, 10.4% poor); 81.3% prior nephrectomy; med metastatic sites: 2; med prior systemic treatments: 2; most common metastatic sites: lung (58.3%), lymph node (52.1%), and bone (43.8%). Pts received nivolumab (nivo) in combination with the following: cabozantinib (n = 24, 50%), pazopanib (13, 27.1%), axitinib (6, 12.5%), lenvatinib (2, 4.2%), ipilimumab/cabozantinib (3, 6.3%). Med PFS was 13.7 months and med OS was not reached. The two largest cohorts received nivo + cabozantinib (N+C; med dose 40 mg daily) or nivo + pazopanib (N+P; med dose 400 mg daily). The N+C cohort had higher med metastatic sites (3 vs 2) and was more pretreated with agents unique to their IO/TKI combination (med 2 vs 0). In the N+P group, more pts had started on TKI prior to addition of nivo at progression (69.2% vs 45.8%), and fewer had IO monotherapy with TKI addition (30.8% vs 50%). With a med follow up of 14.0 months after combination start, the N+C cohort had a med PFS of 7.3 months (initiated TKI first: 4.8, IO first: 8.2) and med OS of 18.2 months (TKI first: 11.8, IO first: 24.3). The N+P cohort had med follow up of 20.5 months after combination, med PFS of 21.3 months (TKI first: 16.5, IO first: 21.8), and med OS was not reached. In the N+C group, 87.5% experienced any grade adverse event (AE), most common included fatigue (79.2%), diarrhea (42.7%), nausea (29.2%), hypertension (29.2%), and weight loss (25.0%). In the N+P group, 92.3% experienced any grade AE, including fatigue (76.9%), hypertension (38.5%), diarrhea (30.8%), nausea (30.8%), and weight loss (30.8%). There were no grade ≥3 AEs. Conclusions: Slow disease progression on nivo or TKI may be safely controlled with addition of IO/TKI therapy. Med PFS after addition of nivo to TKI appears similar (N+C) and improved (N+P) compared to nivo monotherapy (Checkmate-025). Med PFS after addition of TKI to IO was also similar (N+C) and improved (N+P) compared to historical controls.

Chronic Treatment with Morphine Disrupts Acute Kinase-Dependent Desensitization of GPCRs

Based on studies using mutations of the µ-opioid receptor (MOR), phosphorylation of multiple sites on the C-terminus has been recognized as a critical step underlying acute desensitization and the development of cellular tolerance. The aim of this study is to explore which kinases mediate desensitization of MOR in brain slices from drug-naïve and morphine-treated animals. Whole-cell recordings from locus coeruleus neurons were made, and the agonist-induced increase in potassium conductance was measured. In slices from naïve animals, pharmacological inhibition of G-protein receptor kinase (GRK2/3) with compound 101 blocked acute desensitization. Following chronic treatment with morphine, compound 101 was less effective at blocking acute desensitization. Compound 101 blocked receptor internalization in tissue from both naïve and morphine-treated animals, suggesting that GRK2/3 remained active. Kinase inhibitors aimed at blocking protein kinase C and c-Jun N-terminal kinase had no effect on desensitization in tissue taken from naïve animals. However, in slices taken from morphine-treated animals, the combination of these blockers along with compound 101 was required to block acute desensitization. Acute desensitization of the potassium conductance induced by the somatostatin receptor was also blocked by compound 101 in slices from naïve but not morphine-treated animals. As was observed with MOR, it was necessary to use the combination of kinase inhibitors to block desensitization of the somatostatin receptor in slices from morphine-treated animals. The results show that chronic treatment with morphine results in a surprising and heterologous adaptation in kinase-dependent desensitization. SIGNIFICANCE STATEMENT: The results show that chronic treatment with morphine induced heterologous adaptations in kinase regulation of G protein coupled receptor (GPCR) desensitization. Although the canonical mechanism for acute desensitization through phosphorylation by G protein-coupled receptor kinase is supported in tissue taken from naïve animals, following chronic treatment with morphine, the acute kinase-dependent desensitization of GPCRs is disrupted such that additional kinases, including protein kinase C and c-Jun N-terminal kinase, contribute to desensitization.