On February 15, 2019 Nektar Therapeutics (Nasdaq: NKTR) reported a presentation of new clinical data for bempegaldesleukin1 (NKTR-214) in combination with nivolumab in patients with first-line (1L) advanced or metastatic urothelial carcinoma at the 2019 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Genitourinary Cancers Symposium (GU) in San Francisco, CA (Press release, Nektar Therapeutics, FEB 15, 2019, View Source [SID1234533355]).

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The preliminary results from patients enrolled in the 1L urothelial cancer cohort in the ongoing PIVOT-02 Phase 1/2 study were shared in a poster presentation today titled, "NKTR-214 + nivolumab in first-line advanced/metastatic urothelial carcinoma (mUC): Updated results from PIVOT-02" by Arlene O. Siefker-Radtke, M.D., Professor, Department of Genitourinary Medical Oncology, Division of Cancer Medicine at The University of Texas MD Anderson Cancer Center and Clinical Co-Leader of the Bladder Cancer SPORE Executive Committee.

"Preliminary data from the ongoing PIVOT-02 trial in metastatic urothelial cancer patients demonstrated important response rates, including complete responses, in patients who were cisplatin-ineligible or refused standard of care," said Mary Tagliaferri, M.D., Chief Medical Officer of Nektar Therapeutics. "These responses were observed regardless of baseline PD-L1 expression and no relapses occurred. In this cohort of Stage IV bladder cancer patients with a median age of 70, the combination therapy was generally well tolerated with no Grade 4 or 5 adverse events reported. Of note, our translational research demonstrated that in patients with the highest unmet medical need – those whose tumors did not express PD-L1 at their baseline scan – treatment with the combination resulted in 70 percent of patients converting to PD-L1 positive expressors. These data support our development strategy in this tumor setting, including the Phase 2 PIVOT-10 study underway in cisplatin-ineligible urothelial cancer patients with low PD-L1 tumor expression."

Highlights from the ASCO (Free ASCO Whitepaper)-GU presentation in 1L metastatic urothelial carcinoma patients include:

Clinical Efficacy
Response measured per RECIST 1.1 for per protocol efficacy-evaluable patients treated at the recommended Phase 2 dose (RP2D) and with ≥1 post-treatment scan as of December 3, 20182:

Best overall response rate (ORR) was 48% (13/27) in efficacy-evaluable patients, with a 19% (5/27) complete response (CR) rate.3
ORR by immune-related RECIST (irRECIST) was 52% (14/27); ORR in patients with visceral non-nodal metastases was 53% (8/15).
ORR in patients that refused standard of care was 55% (6/11); in cisplatin-ineligible patients ORR was 44% (7/16).
Disease control rate (DCR) was 70% (defined as CR + partial response (PR) + stable disease (SD)).
Median percent reduction in target lesions from baseline in all 27 efficacy-evaluable patients was 32%.
Median percent reduction in target lesions from baseline in all 13 responders was 78%.
Median time to response was 2.0 months.
In patients with RECIST response, no patients discontinued due to relapse.
Amongst the 23 patients with known pre-treatment programmed death-ligand 1 (PD-L1) status, ORR in PD-L1 negative patients was 45% (5/11) and in PD-L1 positive patients was 50% (6/12).
Clinical Safety

Treatment was generally well tolerated and the most common (>15%) treatment-related adverse events (TRAEs) were flu-like symptoms4 (71%), fatigue (56%), rash (46%) and pruritus (32%), decreased appetite (27%) and nausea (22%).
A total of 6/41 (15%) of patients experienced a Grade 3 TRAE, with 4 patients discontinuing due to a TRAE.
No patients experienced a Grade 4/5 TRAE.
Biomarkers and Mechanism of Action

70% (7/10) of patients who were PD-L1 negative at baseline converted to PD-L1 positive by Week 3.
All patients who were initially PD-L1 positive at baseline remained PD-L1 positive.
RECIST responses observed were independent of baseline PD-L1 status and CD8+ T cell infiltrate.
A copy of Dr. Siefker-Radtke’s poster presentation of PIVOT-02 data is available on Nektar’s corporate website at View Source
The PIVOT-10 study evaluating bempegaldesleukin in combination with nivolumab in 1L locally advanced or metastatic urothelial carcinoma cisplatin-ineligible patients with low PD-L1 expression is currently recruiting patients (NCT03785925).

Analyst Call with Urothelial Cancer Specialist
Nektar will webcast an analyst conference call featuring Dr. Siefker-Radtke today, Friday, February 15, 2019 at 2:00 p.m. Pacific Time. The conference call may be accessed by dialing 877-881-2183 (toll-free) or 970-315-0453 (international) with the conference call passcode 9688945. The webcast and slides for the conference call can be accessed through a link posted on the Investors section of the Nektar website at View Source The webcast of the conference call will be available for replay through March 15, 2019.

About Bempegaldesleukin (NKTR-214)
Bempegaldesleukin is an investigational, first-in-class, CD-122-preferential IL-2 pathway agonist designed to provide rapid activation and proliferation of cancer-killing immune cells, known as CD8+ effector T cells and natural killer (NK) cells, without over activating the immune system. Bempegaldesleukin stimulates these cancer-killing immune cells in the body by targeting CD122 specific receptors found on the surface of these immune cells. CD122, which is also known as the Interleukin-2 receptor beta subunit, is a key signaling receptor that is known to increase proliferation of these effector T cells.5 In clinical and preclinical studies, treatment with bempegaldesleukin resulted in expansion of these cells and mobilization into the tumor micro-environment.6,7 Bempegaldesleukin has an antibody-like dosing regimen similar to the existing checkpoint inhibitor class of approved medicines.