Phase I/II study of axitinib (axi) and nivolumab (nivo) in patients with metastatic renal cell carcinoma (mRCC)

4567

Background: Drug combinations targeting vascular endothelial growth factor (VEGF) and the programmed death one (PD-1) pathway have demonstrated encouraging efficacy in patients (pts) with mRCC. We are conducting a phase I/II trial combining the VEGF-targeting tyrosine kinase inhibitor (TKI) axi and the PD-1 inhibitor nivo in mRCC pts. Methods: The phase I portion of this investigator-initiated, multi-center trial enrolled pts with TKI-refractory mRCC (any line) and no prior anti-PD-1. It used a 3+3 design, with axi dosing starting at 3 mg orally BID, escalating to a target dose of5 mg BID. Nivo dosing was fixed at 240 mg IV Q2 weeks or 480 mg Q4 weeks. Eligible pts received axi alone for a one week induction, followed by combination dosing. There was a 4 week period to assess for dose limiting toxicities (DLTs). The primary endpoint for phase I was safety and establishment of a recommended phase II dose (RP2D) for axi. Safety and early efficacy data for the phase I cohort are presented. Results: Twelve pts received treatment during the phase I portion, with all evaluable for toxicity. Ten were 2nd line and 2 were 3rd line or beyond. One DLT was noted in the first cohort of three pts (grade 3 autoimmune disorder), thus that cohort was expanded. No further DLTs were reported at axi 3 mg BID, or at further expansion to 5 mg BID. Grade 3 adverse events (AEs) at least possibly related to one of the drugs included expected side effects HTN, hyperglycemia, and transaminitis. One patient received steroids for an immune related AE (grade 3 transaminitis) that resolved to grade 1 with steroids. No grade 4-5 AEs occurred. Axi at 5 mg BID was chosen as the RP2D. With 10 pts evaluable for efficacy, 4 pts had partial responses, 4 pts had stable disease, and 2 had progressive disease. Updated efficacy data will be presented. Conclusions: The phase I portion of this phase I/II trial has demonstrated expected safety and established 5 mg BID as the RP2D axi dose. This ongoing VEGF TKI/PD1 trial incorporating two drugs already approved for mRCC pts has shown encouraging signs of efficacy and has now expanded to include treatment naïve pts in addition to TKI-refractory pts as part of phase II. Clinical trial information: NCT03172754.

Sporadic angiomyolipomas (AMLs) growth kinetics while on everolimus (SAGE)

560

Background: Level I evidence exists demonstrating the efficacy of the mTOR inhibitor everolimus (EVE) in decreasing tumor volume of syndromic angiomyolipomas (AMLs) among patients with Tuberous Sclerosis. No prospective data are available regarding the effect of mTOR inhibition on growth kinetics in patients with sporadic AMLs. Methods: We conducted a multi-institutional, prospective, phase 2 trial with an optimal two-stage Simon design in patients presenting with > 3cm sporadic AMLs who were candidates for surgical or percutaneous intervention. Response was defined as ≥25% volumetric reduction of the AML. Planned enrollment was 43 patients to test the null hypothesis at a 5% level of significance with 80% power. Baseline, 4- and 6-month volumetric analysis was performed by dynamic contrast-enhanced MRI (DCE-MRI). Patients received EVE 10mg for four 28-day cycles, at which point EVE was discontinued in those with < 25% volumetric reduction. Those with ≥ 25% volumetric reduction received two additional cycles of EVE. Dose reductions and interruptions were allowed to 5 mg QOD. Conservative stopping rules were established for toxicity, given the benign nature of AMLs. Results: The early stopping rules for both efficacy and toxicity were invoked. We enrolled 20 patients (median age = 68) from 5 centers with 21 sporadic AMLs. 11/20 (55%) patients completed 4 cycles of EVE, while 7/20 (35%) completed 6 cycles. Median days on treatment was 88 (2 cycles). 4/20 (20%) patients were withdrawn due to toxicity, while 8/20 (40%) withdrew due to personal preference. Dose reductions were required in 6/20 (30%) patients, and 5/20 (25%) patients had grade 3 toxicities which resolved upon discontinuation or dose reduction of EVE. At 4-month MRI, 10/16 (62.5%) patients had a ≥25% reduction in volume (mean = 54.1% decrease). At 6-month MRI, 8/12 (66.6%) patients had a ≥25% reduction in volume (mean = 51.5% decrease). Conclusions: EVE was effective in reducing tumor volume in patients with sporadic AMLs but was associated with a high rate of treatment termination due to patient preference or prespecified AEs. Neoadjuvant EVE may be useful in potentiating surgical resection of large or anatomically complex AMLs. Clinical trial information: NCT02539459.

Phase I study of the mTOR inhibitor ridaforolimus and the HDAC inhibitor vorinostat in advanced renal cell carcinoma and other solid tumors

INTRODUCTION

Drugs inhibiting the mammalian target of rapamycin (mTOR) are approved in the treatment of renal cell carcinoma (RCC), but resistance inevitably emerges. Proposed escape pathways include increased phosphorylation of Akt, which can be down regulated by histone deacetylase (HDAC) inhibitors. We hypothesized that co-treatment with the mTOR inhibitor ridaforolimus and the HDAC inhibitor vorinostat may abrogate resistance in RCC.

METHODS

This phase 1 study evaluated the co-administration of ridaforolimus and vorinostat in patients with advanced solid tumors. The primary objective was to determine the maximum tolerated dose (MTD) in RCC patients. Although all solid tumors were allowed, prior cytotoxic chemotherapy was limited to 1 regimen. Using a modified 3 + 3 dose escalation design, various dose combinations were tested concurrently in separate cohorts. Efficacy was a secondary endpoint.

RESULTS

Fifteen patients were treated at one of three dose levels, thirteen with RCC (10 clear cell, 3 papillary). Dosing was limited by thrombocytopenia. The MTD was determined to be ridaforolimus 20 mg daily days 1-5 with vorinostat 100 mg BID days 1-3 weekly, however late onset thrombocytopenia led to a lower recommended phase II dose: ridaforolimus 20 mg daily days 1-5 with vorinostat 100 mg daily days 1-3 weekly. Two patients, both with papillary RCC, maintained disease control for 54 and 80 weeks, respectively.

CONCLUSIONS

The combination of ridaforolimus and vorinostat was tolerable at the recommended phase II dose. Two patients with papillary RCC experienced prolonged disease stabilization, thus further study of combined HDAC and mTOR inhibition in this population is warranted.

A phase I study of temsirolimus and bryostatin-1 in patients with metastatic renal cell carcinoma and soft tissue sarcoma

BACKGROUND

Temsirolimus, an inhibitor of mammalian target of rapamycin (mTOR) complex 1, is approved for the treatment of metastatic renal cell carcinoma (RCC). Bryostatin-1 inhibits protein kinase C, a downstream effector of mTOR complex 2. We observed antitumor effects with the combination of temsirolimus and bryostatin-1 in RCC cell lines. METHODS. Four cohorts of patients received weekly bryostatin-1 (20 μg/m²) with temsirolimus (10, 15, 25, or 37.5 mg) in 28-day cycles.

RESULTS

Thirty patients received a total of 138 cycles across four dose levels. Twenty-five patients had RCC (17 clear cell, 7 papillary, and 1 unclassified). Two sarcoma patients with prior cytotoxic therapy experienced dose-limiting toxicity at 15 mg of temsirolimus (grade 3 neutropenia and grade 3 hypophosphatemia). Subsequently, patients with prior cytotoxic therapy were excluded. Two additional dose-limiting toxicities were noted with 37.5 mg of temsirolimus (grade 3 neutropenia and grade 3 creatinine elevation). Consequently, the maximum tolerated dose was defined as temsirolimus at 25 mg and bryostatin-1 at 20 μg/m² every 28 days. Of the 25 RCC patients, 3 patients had partial responses that lasted for 14 months, 28 months, and ≥ 80 months, respectively. Partial responses were seen in both clear cell and papillary histology.

CONCLUSION

This combination of 37.5 mg of temsirolimus with 20 μg/m² of bryostatin-1 was reasonably safe and well tolerated. Durable responses were observed in 3 of 25 patients with RCC.

Overcoming mTOR resistance: Results of a phase I study of the mTOR inhibitor ridaforolimus and the HDAC inhibitor vorinostat

501

Background: Elevation of pAKT levels has been shown to result from mTOR inhibition. We hypothesized that the HDAC inhibitor Vorinostat (Vori) would abrogate Ridaforolimus (Rida) resistance due to downregulation pAKT when used in combination in renal cell carcinoma (RCC). Methods: The primary objective was to determine the MTD most applicable to RCC patients (pts), thus while all solid tumors were allowed, prior cytotoxic chemotherapy was limited to 1 regimen. There was no limit to the number of prior targeted or immunotherapies. ECOG PS 0-1 and adequate organ and marrow function were required. A modified 3+3 dose escalation design tested 2 dose levels concurrently by escalating each drug in separate cohorts. Rida was dosed days 1-5 weekly, Vori days 1-3 weekly. Results: 15 pts (10 clear cell RCC, 3 papillary RCC, 1 esophageal, 1 carcinoid) were treated at one of 3 dose levels: 1) Rida 20mg QD + Vori 100mg BID, 2) Rida 20 mg QD + Vori 200 mg BID, 3) Rida 40 mg QD + Vori 100 mg BID. Inability to complete 80% of doses during cycle 1 due to thrombocytopenia resulted in DLTs in 2/6 pts in dose level 2. There were no other DLTs and no grade 4-5 toxicities. Related grade 3 toxicities were: hyperglycemia (1), anemia (2), fatigue (1), and mucositis (1). Grade 2 pneumonitis was seen in 2 pts. The MTD was Rida 20mg QD + Vori 100mg BID, however all 7 pts who received >2 cycles ultimately required dose reduction to Rida 10-20 mg QD + Vori 100 mg QD, for thrombocytopenia in 6/7 cases. Thus the recommended phase II dose to allow for chronic dosing is Rida 20mg QD + Vori 100mg QD. Four pts, all with RCC, maintained stable disease for 19, 21, 31+ and 59+ weeks. Of these, 3 had progressed on prior temsirolimus or everolimus including the 2 pts with ongoing disease control at the time of data cutoff (31+ and 59+ weeks), both of whom have papillary RCC. Conclusions: Rida 20mg QD + Vori 100 mg QD is the recommended phase II dose for this combination. Prolonged disease control was seen in 4/13 RCC pts, 3 of whom progressed on prior a prior mTOR inhibitor. Further study of combined mTOR and HDAC inhibition in RCC with tumor sampling to assess for pharmacodynamics and proof of concept is warranted to further define the toxicity, efficacy and mechanism of this combination. Clinical trial information: NCT01169532.

A phase I study of temsirolimus (TEM) and bryostatin (BRYO) in patients with metastatic renal cell carcinoma (RCC)

5111

Background: TEM, an inhibitor of mTOR complex 1 (TORC1), is approved for the treatment of metastatic RCC. BRYO inhibits protein kinase C, a downstream effector of mTOR complex 2 (TORC2). We observed additive effects of TEM and BRYO against RCC in vitro. Methods: Four cohorts of 3–6 patients (pts) received weekly BRYO (20 mcgm/m2) and TEM (10, 15, 25, or 37.5 mg,) in 28 day cycles. DLT was defined as 1st cycle toxicity ≥ grade 3. Results: Twenty-three pts have been enrolled. Eighteen pts had RCC: clear cell (12), papillary (3), clear cell with sarcomatoid/spindle features (2), unclassified (1), Among RCC pts, 3 had no prior therapy. 15 had a median of 2 prior therapies (immunotherapy, TKIs, and/or bevacizumab). To date, 22 pts have received 103 cycles across 4 dose levels. Five non-RCC pts (4 sarcoma, 1 paraganglioma) received up to 3 cycles of treatment. Two of these pts (both had prior cytotoxic therapy) experienced DLT at 15 mg (Gr 3 neutropenia and Gr 3 hypophosphatemia) Subsequently, pts with prior cytotoxic therapy were excluded. One additional non-RCC pt (prior radiation) experienced DLT (Gr 3 neutropenia) at TEM 37.5 mg. Among RCC pts, there were no 1st cycle DLT's. Significant toxicities during later cycles included Gr 3/4 thrombosis at TEM 37.5 mg (2), Gr 4 thrombus/Gr 4 LV dysfunction at TEM 15 mg (1), and Gr 3 dyspnea/Gr 3 pneumonitis at TEM 10mg (1). Gr 4 hypercholesterolemia (1) and Gr. 4 triglyceride elevation (1) were seen at TEM 37.5 mg, both reversed with treatment. One RCC pt withdrew prior to receiving treatment. Of the 17 remaining RCC pts, 3 had PRs and 9 had SD. One treatment naïve pt (TEM 15 mg) continues with PR for 2+ years after discontinuing treatment. One pt (had progressed on sunitinib) continues in a PR at 14+ months. Twelve pts received ≥4 cycles and 3 received >10 cycles. PR was seen in both clear cell and papillary histologies. Median PFS was 7.8 months for all pts and 5.7 months for previously treated pts. Two pts, both with PR, remain on treatment, having received 18 and 8 cycles. Conclusions: The TEM/Bryo combination is feasible for multiple cycles on a weekly schedule at full doses of each agent with durable PR and SD in RCC refractory to other therapies. Enrollment continues to further characterize safety and efficacy.

[Table: see text]

Phase I study of intravenous CCI-779 in combination with bryostatin-1 in solid tumors

3067

Background: mTOR regulates translation of messenger RNA critical for angiogenesis and cell growth. CCI-779 inhibits mTOR signaling through p70S6 kinase (S6K), which phosphorylates the ribosomal S6 protein (S6). CCI-779 is active in renal carcinoma (RCC) and other solid tumors. Based on our finding that bryostatin-1 (bryo) inhibits S6K, and that CCI-779 + Bryo additively inhibit S6K and RCC growth in vitro, we initiated a phase I trial to determine the maximum tolerable (MTD) doses and dose-limiting toxicities of this novel combination in patients with solid tumors. Methods: Bryo (20 μg/m2) was administered over 60 minutes IV followed by CCI-779 (10 and 15 mg, planned escalation to 75 mg) IV over 30 minutes, both weekly for 3 of 4 weeks. Serum and peripheral blood mononuclear cell (PBMC) samples were collected for analysis of pharmacokinetics and markers of mTOR inhibition (phospho-S6 and p21waf1). Results: Nine patients (median age 57, 6 RCC, 2 sarcoma and 1 neuroendocrine) are evaluable for toxicity (total cycles=27 cycles, median 4, range 1–7) at the initial 2 dose levels (Bryo 20 μg/m2, CCI-779 10 mg and 15 mg). Cycle 1 toxicity includes grade 3 hypophosphatemia and myelosuppression in one patient each and grade 2 fatigue, stomatitis, and anemia. One patient developed reversible grade 3 pneumonitis after 7 cycles. Of 7 patients with therapy-resistant disease, 5 (4 RCC and 1 sarcoma) had stable disease lasting up to 7 months. A therapy-naive patient with RCC has 23% tumor reduction after 2 cycles at dose level 2 (CCI-779=15 mg). PBMC proteins from 5 patients show consistent decreases in phospho-S6 at 2–6 hours-post treatment compared with pre-treatment baseline measurement, with recovery by 24–72 hours after dosing. In parallel with inhibition of phosphorylation of S6, PBMC levels of p21waf1 were completely inhibited in all 5 patients. Conclusions: The combination of bryo and CCI-779 is feasible, with antitumor activity in RCC and mTOR pathway inhibition observed at submaximal doses. Dose escalation is continuing.

No significant financial relationships to disclose.