Efficacy and safety of pembrolizumab in metastatic urothelial carcinoma: results from KEYNOTE-045 and KEYNOTE-052 after up to 5 years of follow-up

BACKGROUND

Immune checkpoint inhibitors are a standard therapy in metastatic urothelial carcinoma (UC). Long-term follow-up is necessary to confirm durability of response and identify further safety concerns.

PATIENTS AND METHODS

In KEYNOTE-045, patients with metastatic UC that progressed on platinum-containing chemotherapy were randomly assigned 1:1 to receive pembrolizumab or investigator's choice of paclitaxel, docetaxel, or vinflunine. Primary endpoints were progression-free survival per RECIST version 1.1 by blinded independent central review (BICR) and overall survival. In KEYNOTE-052, cisplatin-ineligible patients with metastatic UC received first-line pembrolizumab. The primary endpoint was objective response rate per RECIST version 1.1 by BICR.

RESULTS

A total of 542 patients (pembrolizumab, n = 270; chemotherapy, n = 272) were randomly assigned in KEYNOTE-045. The median follow-up was 62.9 months (range 58.6-70.9 months; data cut-off 1 October 2020). At 48 months, overall survival rates were 16.7% for pembrolizumab and 10.1% for chemotherapy; progression-free survival rates were 9.5% and 2.7%, respectively. The median duration of response (DOR) was 29.7 months (range 1.6+ to 60.5+ months) for pembrolizumab and 4.4 months (range 1.4+ to 63.1+ months) for chemotherapy; 36-month DOR rates were 44.4% and 28.3%, respectively. A total of 370 patients were enrolled in KEYNOTE-052. The median follow-up was 56.3 months (range 51.2-65.3 months; data cut-off 26 September 2020). The confirmed objective response rate was 28.9% (95% confidence interval 24.3-33.8), and the median DOR was 33.4 months (range 1.4+ to 60.7+ months); the 36-month DOR rate was 44.8%. Most treatment-related adverse events for pembrolizumab in either study were grade 1 or 2 and manageable, which is consistent with prior reports.

CONCLUSION

With ∼5 years of follow-up, pembrolizumab monotherapy continued to demonstrate durable efficacy with no new safety signals in patients with platinum-resistant metastatic UC and as first-line therapy in cisplatin-ineligible patients.

CLINICAL TRIAL REGISTRY AND ID

With ClinicalTrials.gov NCT02256436 (KEYNOTE-045); https://clinicaltrials.gov/ct2/show/NCT02256436 and NCT02335424 (KEYNOTE-052); https://clinicaltrials.gov/ct2/show/NCT02335424.

Safety and clinical activity of vascular endothelial growth factor receptor (VEGFR)-tyrosine kinase inhibitors after programmed cell death 1 inhibitor treatment in patients with metastatic clear cell renal cell carcinoma

BACKGROUND

Emerging agents blocking the programmed cell death 1 (PD-1) pathway show activity in metastatic clear cell renal cell carcinoma (mRCC). The aim of this study was to evaluate the efficacy and safety of vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR)-tyrosine kinase inhibitor (TKI) therapy after PD-1 inhibition.

PATIENTS AND METHODS

Patients with mRCC treated with anti-PD-1 antibody (aPD-1) monotherapy or in combination (with VEGFR-TKI or ipilimumab) that subsequently received VEGFR-TKI were retrospectively reviewed. The efficacy end points were objective response rate (ORR) and progression-free survival (PFS) stratified by the type of prior PD-1 regimen. Safety by the type and PD-1 exposure was also evaluated.

RESULTS

Seventy patients were included. Forty-nine patients received prior therapy with immune checkpoint inhibitors (CPIs) alone and 21 had combination therapy of aPD-1 and VEGFR-TKI. Overall, ORR to VEGFR-TKI after PD-1 inhibition was 28% (19/68) and the median PFS was 6.4 months (mo) (4.3-9.5). ORR to VEGFR-TKI after aPD-1 in combination with VEGFR-TKI was lower than that in patients treated with VEGFR-TKI after CPI alone (ORR 10% versus 36%, P = 0.039). In the multivariable analysis, patients treated with prior CPI alone were more likely to achieve an objective response than those treated with aPD-1 in combination with VEGFR-TKI (OR = 5.38; 95% CI 1.12-26.0, P = 0.03). There was a trend toward numerically longer median PFS in the VEGFR-TKI after the CPI alone group, 8.4 mo (3.2-12.4) compared with 5.5 mo (2.9-8.3) for those who had VEGFR-TKI after aPD-1 in combination with VEGFR-TKI (P = 0.15). The most common adverse events (AEs) were asthenia, hypertension, and diarrhea.

CONCLUSIONS

The efficacy and safety of VEGFR-TKIs after PD-1 inhibition were demonstrated in this retrospective study. The response rate was lower and the median progression-free survival was shorter in those patients who received prior PD-1 in combination with VEGFR-TKI. PD-1 exposure does not seem to significantly influence the safety of subsequent VEGFR-TKI treatment.

A phase I study of decitabine with pegylated interferon α-2b in advanced melanoma: impact on DNA methylation and lymphocyte populations

BACKGROUND

Melanoma cell lines treated with decitabine show upregulation of cancer antigens, and interferon-α upregulates MHC Class I antigens in cancer cells, leading to enhanced T-cell recognition and T-cell mediated tumor apoptosis. We evaluated the synergy between the hypomethylating effects of decitabine and the immunomodulatory effects of interferon in a combination regimen administered to advanced melanoma patients in a phase 1 trial.

METHODS

Patients with one prior systemic therapy were eligible. Using a modified 3 + 3 design, patients received escalating doses of decitabine and pegylated interferon α-2b (PEG-IFN) during every 28-day treatment cycle. Global DNA methylation was measured on days 1 and 5 of cycles 1 and 3. Cytokine profiling and quantification of T-cell subpopulations by FACS were performed at baseline and cycle 3.

RESULTS

Seventeen patients were assigned to one of four dose levels. Decitabine 15 mg/m2/d + PEG-IFN 3 μg/kg was the maximum tolerated dose (MTD). Grade 3/4 cytopenias were seen across all dose levels: anemia (1), neutropenia (7), and thrombocytopenia (2). One patient remained progression-free for 37 weeks. The other 16 patients progressed at or before 12 weeks. Median overall survival was 39 weeks. Hypomethylation was seen at all dose levels. Due to treatment-induced lymphocytopenia, absolute changes in T-cell populations post-treatment were too small to be meaningfully interpreted.

CONCLUSIONS

The response to this combination regimen was characterized by significant myelosuppression, particularly neutropenia. Although disappointing efficacy and slow accrual led to early closure of the trial, hypomethylation showed pharmacodynamic evidence of a therapeutic effect of decitabine at all dose levels.

Effect of EGFR inhibition with cetuximab on the efficacy of paclitaxel in previously treated metastatic urothelial cancer

243

Background: The benefit of salvage chemotherapy such as weekly paclitaxel (TAX) is modest in metastatic (met) urothelial ca, with median TTP of ≤3 months and ORR of 10% (95% CI 4-18% [combined results, Vaughn 2002; Joly, 2009]). Cetuximab (CET) is a monoclonal antibody against the epidermal growth factor receptor (EGFR). High-grade urothelial cancer overexpress EGFR. We conducted a multicenter randomized, noncomparative phase II study to measure the efficacy of CET ± TAX in patients (pts) with previously treated met urothelial cancer.

Methods: Pts with met urothelial cancer who received one line of chemotherapy in the adjuvant, neoadjvuant, or met setting were enrolled. Pts were randomized to CET 250mg/m2 (after 400 mg/m2 load) ± TAX 80 mg/m2 weekly. A cycle was 4 weeks (wks). Response (RECIST) was assessed by imaging every 8 wks. We used early progression to assess futility (Litwin Stats Med 2007). Either arm would close if 7 of the initial 15 pts in that arm progressed at the first disease evaluation. Either arm would be considered promising if ≥9/28 patients had PFS>16 wks (90.4% power to detect an improvement in Median [Med] PFS from 8 to 16 wks with a 7.1% type 1 error).

Results: We enrolled 39 evaluable pts (30 male). Median age was 69 years (range 49-79). All pts received prior platinum-based chemotherapy. CET arm closed after 9 of the first 11 pts progressed by 8 wks (ASCO GU 2009). CET-TAX arm completed full accrual (28 pts), of which 11 had visceral disease and 13 received chemo for met disease. 10/28 pts had PFS>16 wks. Overall RR was 28.5%, (8/28 pts, 95% CI 13-49%) (2 CR, 6PR). 4 additional pts had unconfirmed PR. 2 pts have maintained PR 3 and 4 months after discontinuing CET-TAX. Med PFS for the CET-TAX was 115 days (16 weeks)(95% CI 58-174 days). Med PFS for pts with visceral disease was 84 days (95%CI 50-NR). Med PFS for pts who received prior chemo for met disease was 142 days (95% 58-NR). Med number of cycles for the CET-TAX was 3 (range 0-25). Grade 3 AEs occurring in more than 2 pts were rash (5), fatigue (4), anemia (4), low magnesium (3).

Conclusions: EGFR inhibition with CET appears to augment the antitumor activity of TAX in pts with previously treated urothelial cancers. The CET-TAX combination merits further study to establish its role in treatment of urothelial cancers.

[Table: see text]

Outcome of patients (pts) with renal medullary carcinoma (RMC) treated in the era of targeted therapies (TT): A multicenter experience

386

Background: RMC is a rare, highly aggressive primary neoplasm of the kidney that almost exclusively afflicts young black pts with sickle cell hemoglobinopathies, primarily sickle cell trait. The primary objectives of this study were to evaluate the clinical characteristics and treatment outcome of RMC pts.

Methods: We retrospectively reviewed the medical records of pts diagnosed with RMC at four US institutions between 2000 and 2010. Overall survival (OS) was determined from initial diagnosis to date of death or last follow up (F/U). The time interval from date of metastasis to death or last F/U (OSm) was also determined. Kaplan-Meier methods were used to estimate OS and OSm.

Results: 20 RMC pts were identified. All pts were black; 14 (70%) were males; 18 had sickle cell trait, 1 had sickle thalassemia and 1 not tested. 19 presented with stages III or IV; 7 (35%) had nephrectomy. Nineteen pts had ≥ 2 metastatic sites. Twelve pts had performance status [PS] 0/1; eight pts had PS 2/3. For the OS analysis, data on 16 pts were available and for the OSm analysis, data on 20 pts were available. The median follow up time for the OS analysis was 722 days. Thirteen of 16 pts died with median OS of 421 days [95%CI: 225–546]. Sixteen of 20 pts died in the OSm analysis with median OSm of 378 days [95%CI: 225–487]. Frontline therapy consisted of TT [sunitinib (5), bevacizumab + erlotinib (1), imatinib (2)], chemotherapy (C) [platinum/gemcitabine or taxane (7), gemcitabine/doxorubicin (2)], C + TT [gemcitabine/cisplatinum/bevacizumab (2), imatinib/doxorubicin (1)]. Three pts achieved a partial response (PR) in first-line (2 with C, 1 with C + TT). Twelve pts received second-line systemic therapies; 4 achieved PR (1 with bevacizumab/erlotinib, 2 with C, 1 with C + TT). Among 15 pts who had TT at any time during their treatment course, only 1 pt had PR.

Conclusions: The prognosis of RMC pts remains poor despite initial palliation with systemic therapy. Collaborative multi-institutional efforts are needed to better understand the biology of this disease and improve treatment strategies.

No significant financial relationships to disclose.

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]