Efficacy and Safety of Telaglenastat Plus Cabozantinib vs Placebo Plus Cabozantinib in Patients With Advanced Renal Cell Carcinoma: The CANTATA Randomized Clinical Trial

Importance

Dysregulated metabolism is a hallmark of renal cell carcinoma (RCC). Glutaminase is a key enzyme that fuels tumor growth by converting glutamine to glutamate. Telaglenastat is an investigational, first-in-class, selective, oral glutaminase inhibitor that blocks glutamine utilization and downstream pathways. Preclinically, telaglenastat synergized with cabozantinib, a VEGFR2/MET/AXL inhibitor, in RCC models.

Objective

To compare the efficacy and safety of telaglenastat plus cabozantinib (Tela + Cabo) vs placebo plus cabozantinib (Pbo + Cabo).

Design, Setting, and Participants

CANTATA was a randomized, placebo-controlled, double-blind, pivotal trial conducted at sites in the US, Europe, Australia, and New Zealand. Eligible patients had metastatic clear-cell RCC following progression on 1 to 2 prior lines of therapy, including 1 or more antiangiogenic therapies or nivolumab plus ipilimumab. The data cutoff date was August 31, 2020. Data analysis was performed from December 2020 to February 2021.

Interventions

Patients were randomized 1:1 to receive oral cabozantinib (60 mg daily) with either telaglenastat (800 mg twice daily) or placebo until disease progression or unacceptable toxicity.

Main Outcomes and Measures

The primary end point was progression-free survival (Response Evaluation Criteria in Solid Tumors version 1.1) assessed by blinded independent radiology review.

Results

A total of 444 patients were randomized: 221 to Tela + Cabo (median [range] age, 61 [21-81] years; 47 [21%] women and 174 [79%] men) and 223 to Pbo + Cabo (median [range] age, 62 [29-83] years; 68 [30%] women and 155 [70%] men). A total of 276 (62%) patients had received prior immune checkpoint inhibitors, including 128 with prior nivolumab plus ipilimumab, 93 of whom had not received prior antiangiogenic therapy. Median progression-free survival was 9.2 months for Tela + Cabo vs 9.3 months for Pbo + Cabo (HR, 0.94; 95% CI, 0.74-1.21; P = .65). Overall response rates were 31% (69 of 221) with Tela + Cabo vs 28% (62 of 223) with Pbo + Cabo. Treatment-emergent adverse event (TEAE) rates were similar between arms. Grade 3 to 4 TEAEs occurred in 160 patients (71%) with Tela + Cabo and 172 patients (79%) with Pbo + Cabo and included hypertension (38 patients [17%] vs 40 patients [18%]) and diarrhea (34 patients [15%] vs 29 patients [13%]). Cabozantinib was discontinued due to AEs in 23 patients (10%) receiving Tela + Cabo and 33 patients (15%) receiving Pbo + Cabo.

Conclusions and Relevance

In this randomized clinical trial, telaglenastat did not improve the efficacy of cabozantinib in metastatic RCC. Tela + Cabo was well tolerated with AEs consistent with the known risks of both agents.

Trial Registration

ClinicalTrials.gov Identifier: NCT03428217.

Bergamottin a CYP3A inhibitor found in grapefruit juice inhibits prostate cancer cell growth by downregulating androgen receptor signaling and promoting G0/G1 cell cycle block and apoptosis

Prostate cancer is the second leading cause of cancer related death in American men. Several therapies have been developed to treat advanced prostate cancer, but these therapies often have severe side effects. To improve the outcome with fewer side effects we focused on the furanocoumarin bergamottin, a natural product found in grapefruit juice and a potent CYP3A inhibitor. Our recent studies have shown that CYP3A5 inhibition can block androgen receptor (AR) signaling, critical for prostate cancer growth. We observed that bergamottin reduces prostate cancer (PC) cell growth by decreasing both total and nuclear AR (AR activation) reducing downstream AR signaling. Bergamottin’s role in reducing AR activation was confirmed by confocal microscopy studies and reduction in prostate specific antigen (PSA) levels, which is a marker for prostate cancer. Further studies revealed that bergamottin promotes cell cycle block and accumulates G0/G1 cells. The cell cycle block was accompanied with reduction in cyclin D, cyclin B, CDK4, P-cdc2 (Y15) and P-wee1 (S642). We also observed that bergamottin triggers apoptosis in prostate cancer cell lines as evident by TUNEL staining and PARP cleavage. Our data suggests that bergamottin may suppress prostate cancer growth, especially in African American (AA) patients carrying wild type CYP3A5 often presenting aggressive disease.

Analysis of two poor prognosis subgroups in ACIS evaluating apalutamide + abiraterone acetate plus prednisone (APA + AAP) versus placebo (PBO) + AAP in metastatic castration-resistant prostate cancer (mCRPC)

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Background: In the double-blind PBO-controlled ACIS study, investigator-assessed radiographic progression-free survival (rPFS) was significantly improved with APA + AAP vs PBO + AAP in chemo-naive mCRPC, with no significant new safety signals (Rathkopf ASCO GU 2021). Among prespecified subgroups, efficacy and safety were explored in two difficult to treat subgroups: pts with visceral disease (VD; liver, lung, and/or adrenal gland metastasis) or age ≥ 75 y. Methods: Pts with mCRPC with ongoing ADT and no prior life-prolonging treatment were randomized 1:1 to APA (240 mg QD) + AA (1000 mg QD) + P (5 mg BID) or PBO + AAP. Stratified: presence or absence of VD, ECOG PS 0 or 1, geographic region. Primary end point: rPFS (randomization to radiographic progression or death); secondary end points: overall survival (OS), time to initiation of cytotoxic chemotherapy, time to chronic opioid use, time to pain progression, safety. Results: 982 pts enrolled. 14.6% had VD and 35.9% were ≥ 75 y. Median rPFS, OS, and time to pain progression favored APA + AAP vs AAP (HR < 1) in both subgroups (Table). For pts ≥ 75 y, rPFS and OS were ≥ 7 mo longer with APA + AAP. Overall, treatment-emergent adverse events (TEAEs) were similar (all > 94%) in pts with VD, ≥ 75 y, and overall safety population; hypertension was more frequent with APA + AAP vs AAP mainly in pts ≥ 75 y (31.7% vs 17.6%). Grade 3/4 TEAEs (APA + AAP vs AAP): VD, 60.8%, n = 74 vs 48.5%, n = 68; ≥ 75 y, 71.5%, n = 186 vs 68.5%, n = 165; overall, 63.3%, n = 490 vs 56.2%, n = 489. TEAEs leading to discontinuation: VD, 17.6% vs 5.9%; ≥ 75 y, 26.3% vs 20.6%; overall, 16.9% vs 12.5%. TEAEs leading to death: VD, 6.8% vs 5.9%; ≥ 75 y, 5.4% vs 13.9%; overall, 3.5% vs 7.6%. Conclusions: In this analysis of two difficult to treat subgroups, addition of APA to AAP favored rPFS and OS. Safety, while generally consistent with the overall population, showed higher hypertension rate in ≥ 75 y and TEAEs leading to discontinuation in VD. Clinical trial information: NCT02257736. [Table: see text]

Abstract 3475: CYP3A5 inhibitor bergamottin present in grape fruit extract blocks prostate cancer cell growth

Background: Previous research has revealed that the androgen receptor (AR), which upon activation goes to the nucleus, is the driving force of prostate cancer growth. Once activated, AR promotes transcription of genes responsible for promoting cancer growth. Previous studies have shown that inhibition of CYP3A5 blocks the activation process of the AR. CYP3A5 is a liver enzyme and together with CYP3A4 processes 50% of all commonly prescribed drugs. CYP3A5 is the extrahepatic form expressed in both normal and malignant prostate. Bergamottin, a compound found in grapefruit juice, is a known CYP3A4/5 inhibitor. Based on CYP3A5's ability to regulate AR activation, we tested the effects of bergamottin on AR activation to see if the compound can be utilized as a dietary supplement to reduce prostate cancer growth.

Methods: Western blotting, cell fractionation, and immunofluorescence were used to observe the effects of bergamottin on AR, amount of AR in nucleus/cytoplasm, and cellular localization of AR, respectively. MTT based cell growth measurement was used to see how prostate cancer cell growth was affected by bergamottin.

Results: Cell growth assay revealed that bergamottin reduced prostate cancer cell growth. The IC50 for LNCaP cells was observed to be 2.4 μM. Growth of RWPE1 cells (non transformed prostate epithelium) was not effected at the same concentration of bergamottin. Western blot analysis showed that total AR protein expression was downregulated in the bergamottin treated LNCaP and MDAPCa2b cells. Cell fractionation assay revealed that bergamottin significantly reduced nuclear AR after DHT induction compared to non-treated cells. Immunofluorescence assay confirmed reduced nuclear AR in the bergamottin treated LNCaP and MDAPCa2b cells. Furthermore, bergamottin reduced PSA levels both inside the cells and in the growth media indicating that it inhibits AR downstream signaling.

Conclusion: Our results concluded that bergamottin successfully blocked AR activation and downstream signaling, and consequently slowed down prostate cancer cell growth. The implication of this experiment is the potential use of bergamottin as a food supplement alongside other prostate cancer treatments in order to aid in blocking prostate cancer growth.

Citation Format: Opalina Vetrichelvan, Priyatham Gorjala, Oscar Goodman Jr, Ranjana Mitra. CYP3A5 inhibitor bergamottin present in grape fruit extract blocks prostate cancer cell growth [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 3475.

Abstract 2467: Interaction of CYP3A5 with AR-HSP90 complex regulating AR activation in prostate cancer cells

Background: Previously we have demonstrated that CYP3A5 stimulates prostate cancer cell growth by promoting AR activation and downstream signaling. We further investigated the mechanism of CYP3A5's interaction with the AR-HSP90 complex known to regulate AR activation process. AR activation is tightly regulated and it involves several chaperons (HSP90, HSP70, HSP40, and HSP27), multiple cofactors and protein kinases. We hypothesize that stoichiometric CYP3A5 binding to the HSP90-AR complex can induce conformational changes in the chaperone complex, promoting AR nuclear migration and activation.

Method: We used co-immunoprecipitation to identify the interaction of CYP3A5 with the components of the AR-HSP90 complex. Immunofluorescence studies were performed to identify the components of the AR-HSP90 complex that co-localize with CYP3A5. FRET analysis was used to confirm the interactions of CYP3A5 with the AR-HSP90 complex.

Results: We performed co-immunoprecipitation (co-IP) experiments with extracts from flag-tagged CYP3A5 transfected LNCaP cells. Our data demonstrates that CYP3A5 co-immunoprecipitates with HSP90, AR, HSP70 and HSP40, all known components of the HSP90-AR complex. We further confirmed using reverse immunoprecipitation with AR/ HSP90 antibodies and agarose A/G beads that CYP3A5 is a part of the HSP90-AR mature complex. Empty vector transfected cell extract and IgG were used as controls for pull down and reverse IP respectively. Immunofluorescence studies demonstrated that HSP70 and HSP40 co-localized with CYP3A5 in the cytoplasm. Interestingly, the MDAPCa2b and LNCaP cells show co-localization of CYP3A5 and AR in the nucleus, in contrast to non-transformed RWPE1 cells where CYP3A5 remains in the cytoplasm. The nuclear presence of CYP3A5 is more pronounced in MDAPCa2b cells carrying the wild type CYP3A5. The FRET analysis further confirmed direct interaction between CYP3A5 and HSP40 a chaperon in the AR-HSP90 complex.

Conclusions: Our data confirms that CYP3A5 directly interacts with the AR-HSP90 complex regulating AR activation process. Further understanding of this interaction can help establish CYP3A5-AR axis as a novel therapeutic target.

Citation Format: Priyatham Gorjala, Oscar Goodman Jr., Ranjana Mitra. Interaction of CYP3A5 with AR-HSP90 complex regulating AR activation in 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 2467.

Abstract 5900: Inhibition of CYP3A5 down-regulates cancer drug resistance genes and induces synthetic lethality in prostate cancer cells

Background and objective: Androgen deprivation therapy (ADT) is among the most effective of all cancer therapies for prostate cancer; however, resistance to therapy leading to castrate resistant prostate cancer (CRPC) is inevitable in most patients. Recently we demonstrated that CYP3A5 expressed in prostate cancer cells facilitates the nuclear translocation of AR, directly impacting the transcriptional regulation of AR-dependent genes promoting prostate cancer cell growth. Our preliminary data show that CYP3A5 is a part of the HSP90-AR complex, known to regulate AR nuclear localization and activation. Additionally, we observed that CYP3A5 inhibition also blocks growth of prostate cancer cells lacking AR ligand binding site (22RV1). This observation suggested presence of an alternative mechanism of regulation of prostate cell growth by CYP3A5, independent of its AR activation. We hypothesize that CYP3A5 inhibition can also sensitize prostate cancer cells to therapy by downregulating expression of drug resistance genes independent of its AR regulation. Our aim is to decipher the role of CYP3A5 in therapeutic resistance, by screening for CYP3A5 regulated cancer drug resistance genes and to further understand the underlying mechanism of this regulation.

Method: We used cancer drug resistance PCR array after CYP3A5 siRNA knockdown to identify CYP3A5 regulated genes involved in therapeutic resistance. Further we evaluated the role of CYP3A5 in inducing synthetic lethality in combination with DNA damage repair inhibiting drugs by imagining the γ-H2AX foci.

Results: CYP3A5 siRNA knockdown downregulates 11 genes involved in cancer drug resistance: TOP2A, BRCA1/2, CCNE1, CDK2/4, DHFR, MVP, MYC, RARB and HPRT1 with a p≤0.005 value. Of the list of downregulated genes, the three genes TOP2A, BRCA2 and BRCA1 have the most fold change and their loss is known to impair homologous recombination (HR), leading to synthetic lethality. HR defects in CRPC, sensitizes these tumors to PARP and topoisomerase inhibitors. We tested the effect of CYP3A5 inhibition in inducing HR defects by analyzing γ-H2AX foci counts in combination with topoisomerase inhibitor etoposide. Increased number of γ-H2AX foci suggest that CYP3A5 siRNA may induce synthetic lethality in prostate cancer cells when used in combination with DNA damage repair inhibiting drugs by impairing HR and downregulating TOP2A and BRCA1/2 expression.

Conclusions:

CYP3A5 inhibition downregulates DNA damage repair genes (TOP2A and BRCA1/2) and cell cycle progression genes (CCNE1, CDK 2/4) and impairs HR. CYP3A5 inhibition can sensitize CRPC to PARP and topoisomerase inhibitors as it induces synthetic lethality by downregulating TOP2A and BRCA1/2 expression. CYP3A5 inhibition can be potentially exploited therapeutically in combination with PARP inhibitors as it functionally impairs HR and causes synthetic lethality.

Citation Format: Priyatham Gorjala, Ranjana Mitra, Oscar Goodman. Inhibition of CYP3A5 down-regulates cancer drug resistance genes and induces synthetic lethality in prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5900.

Abstract CT045: Phase 1, open-label, first-in-human study of AMG 900, an orally administered pan-aurora kinase inhibitor, in adult patients (pts) with advanced solid tumors

Purpose: Aurora kinases are associated with high proliferation, poor prognosis, and therapeutic resistance in several human tumor types. AMG 900 is an investigational, oral, highly potent, selective, pan-aurora kinase inhibitor. We evaluated the safety, tolerability, pharmacokinetics, and clinical activity of AMG 900 in pts with advanced solid tumors (NCT00858377).

Methods: In the dose escalation phase, eligible pts were ? 18 years old, with advanced solid tumors that were refractory to standard treatment, measurable disease per RECIST, ECOG ? 2, and life expectancy &gt; 3 months. In the dose expansion phase, eligible pts had taxane- and platinum-resistant epithelial ovarian cancer (OC), taxane-resistant triple-negative breast cancer (TNBC), or castration-resistant and taxane- or cisplatin-etoposide-resistant stage IV prostate cancer (CRPC). AMG 900 was administered 4 days on/10 days off at doses of 1 to 50 mg/day (dose escalation), and at the maximum tolerated dose of 40 mg/day with G-CSF support (dose-expansion). The primary objective was safety. Tumor response was determined per RECIST for all pts and additionally by GCIG CA-125 for pts with OC.

Results: Treatment-related AEs were reported by 98 of 105 pts (93.3%). Myelotoxicities were the most common grade ? 3 treatment-related AEs. In the dose escalation (N = 50), 1 pt with OC (30-mg cohort) had a partial response (PR) by RECIST and GCIG. In the dose expansion (N = 55), 3 of 29 pts (10.3%) with OC had a PR by RECIST, and 7 of 29 pts (24.1%) had a PR by GCIG; 72.4% of pts with OC had stable disease (SD), and the disease control rate (PR + SD) was 82.8%. Median (95% CI) duration of response in pts with OC per RECIST was 24.1 (16.1, 34.1) weeks, and median (80% CI) PFS was 31.1 (23.6, 34.1) weeks. See table for additional results.

Conclusions: AMG 900 had manageable toxicity with G-CSF support and promising single-agent activity in pts with heavily pretreated taxane- and platinum-resistant OC. Patient demographics, prior therapy, AEs, and best tumor responseDose escalation - advanced solid tumors (N = 50)OC (N = 29)TNBC (N = 14)CRPC (N = 12)Overall (N = 105)Male, n (%)21 (42.0)0 (0.0)0 (0.0)12 (100.0)33 (31.4)Female, n (%)29 (58.0)29 (100.0)14 (100.0)0 (0.0)72 (68.6)White or Caucasian, n (%)35 (70.0)23 (79.3)12 (85.7)11 (91.7)81 (77.1)Age, mean (SD), years56.5 (11.6)61.1 (11.4)54.6 (11.4)67.7 (8.0)58.8 (11.7)Prior lines of anti-cancer therapy, mean (SD)4.9 (3.2)5.3 (4.3)5.8 (3.0)4.5 (2.6)5.1 (3.4)Treatment-related AEs by preferred term (any grade), n (%)Fatigue21 (42.0)15 (51.7)6 (42.9)6 (50.0)48 (45.7)Neutropenia24 (48.0)14 (48.3)4 (28.6)4 (33.3)46 (43.8)Anemia15 (30.0)16 (55.2)6 (42.9)3 (25.0)40 (38.1)Nausea18 (36.0)10 (34.5)5 (35.7)5 (41.7)38 (36.2)Thrombocytopenia15 (30.0)11 (37.9)1 (7.1)2 (16.7)29 (27.6)Diarrhea14 (28.0)10 (34.5)1 (7.1)2 (16.7)27 (25.7)Alopecia13 (26.0)11 (37.9)1 (7.1)1 (8.3)26 (24.8)Decreased appetite11 (22.0)7 (24.1)2 (14.3)4 (33.3)24 (22.9)Vomiting9 (18.0)7 (24.1)5 (35.7)3 (25.0)24 (22.9)Leukopenia19 (38.0)3 (10.3)0 (0.0)1 (8.3)23 (21.9)Best tumor response - RECIST 1.1 criteria (central read), n (%)Complete response0 (0.0)0 (0.0)0 (0.0)0 (0.0)0 (0.0)Partial response1 (2.0)3 (10.3)0 (0.0)0 (0.0)4 (3.8)Stable disease29 (58.0)21 (72.4)7 (50.0)9 (75.0)66 (62.9)Progressive disease12 (24.0)3 (10.3)4 (28.6)1 (8.3)20 (19.0)Unable to evaluate8 (16.0)2 (6.9)3 (21.4)2 (16.7)15 (14.3)

Citation Format: Montasser Shaheen, Ben Markman, Michael Carducci, Sara Hurvitz, Daruka Mahadevan, Dusan Kotasek, Oscar Goodman, Erick Gamelin, Vincent Chow, Gloria Juan, Erik Rasmussen, Gregory R. Friberg, Florian D. Vogl, Jayesh Desai. Phase 1, open-label, first-in-human study of AMG 900, an orally administered pan-aurora kinase inhibitor, in adult patients (pts) with advanced solid tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr CT045.

Integrating circulating tumor cell data with imaging and serum prostate-specific antigen measurement for metastatic prostate cancer therapy management

Optimal management of therapy can improve quality of life, and potentially survival, of patients with metastatic prostate cancer. Circulating tumor cell (CTC) enumeration in the peripheral blood holds promise for facilitating optimal therapy management based on high cancer specificity and prompt response to changes in disease status. We present the case of a 54-year-old male diagnosed with metastatic prostate cancer. The patient's disease status was monitored radiographically and by serial determinations of serum prostate-specific antigen concentration, performance status, and CTC enumeration. At multiple visits, the disease status was not clear due to discordance between standard assessments. The additional information provided by CTC enumeration helped clarify disease status and provided support for treatment decisions.

Increases in quantitative D-dimer levels correlate with progressive disease better than circulating tumor cell counts in patients with refractory prostate cancer

Changes in quantitative D-dimer levels, circulating tumor cell (CTC) counts, and prostate-specific antigen (PSA) levels were measured in 28 patients with refractory castration-resistant prostate cancer to assess their concordance during the course of therapy and their relationship with risk of progressive disease. A significant correlation was identified between changes in PSA and both CTC counts and D-dimer levels (r = 0.67 and 0.58, respectively; P < .001). In addition, there was a significant correlation between changes in CTC count and D-dimer level (r = 0.62; P < .001). A significantly stronger concordance between these biomarkers was noted for increasing values (sensitivity, 72%-77.8%) compared with decreasing values (specificity, 43.8%-71.4%). Notably, increases in PSA and D-dimer levels, not CTC counts, were associated with increased risks for progressive disease (P < .024). Increases in quantitative D-dimer levels correlate with progressive disease better than CTC counts in patients with refractory prostate cancer.

Dramatically elevated circulating tumor cell numbers in a patient with small cell neuroendocrine carcinoma of the prostate

Detection of circulating tumor cells in whole blood is a useful prognostic tool for patients with castration-resistant prostate cancer, as well as for patients with metastatic breast cancer and colorectal carcinoma. In this report, we present the case of a patient with neuroendocrine small cell prostate cancer with normal prostate-specific antigen levels throughout the course of disease but who had markedly elevated circulating tumor cells, as detected with the CellSearch (Veridex) system.