Results from a phase I expansion cohort of the first-in-class oral HIF-2α inhibitor PT2385 in combination with nivolumab in patients with previously treated advanced RCC

558 Background: The transcription factor hypoxia-inducible factor (HIF)-2α has been established as an oncogenic driver in clear cell renal cell carcinoma (ccRCC) due to underlying VHL deficiency. Activation of HIF-2α can also promote immunosuppression. In preclinical models, HIF-2α inhibition demonstrated increased efficacy in combination with checkpoint inhibitors (Han et al. AACR 2016). In a Phase 1 dose escalation/expansion trial in heavily pre-treated advanced ccRCC patients, PT2385 monotherapy was associated with variability in drug exposure with higher therapeutic exposure associated with improved anti-tumor activity (Courtney et al. JCO 2018). Methods: In the current Phase 1 expansion cohort, patients with advanced ccRCC who had received 1-3 prior therapies (including at least one VEGF(R)-targeting agent) were treated with PT2385 (800 mg PO BID) in combination with nivolumab (3 mg/kg IV Q2Weeks) to evaluate safety, efficacy, and pharmacokinetics. Results: 50 patients were enrolled. Median age was 62 with 58% ECOG 1 and 42% ECOG 2. Median number of prior therapies was 1; 42% of patients received ≥2 prior lines of therapy. The most common all-grade AEs were anemia (46%), fatigue (46%), nausea (36%), and arthralgia (30%). The most common Grade 3 AE’s were anemia (4%), fatigue (4%), and hypoxia (4%). Two Grade 4 events of elevated ALT and increased lipase/amylase were observed. As of August 31, 2018, ORR = 22% (1 CR, 10 PR). At a median follow up of 12.4 months (m), median PFS was 7.3 m for all patients. Patients who had sub-therapeutic exposures ( < 300 ng/ml) of PT2385 (n = 17) had a median PFS of 4.7 m compared to patients with therapeutic exposures of PT2385 (n = 33), who had a median PFS of 10.0 m. Conclusions: The combination of PT2385 + nivolumab was well tolerated and demonstrated promising anti-tumor activity in advanced ccRCC patients, most notably in patients who achieved therapeutic exposure of PT2385. Single agent and combination studies with PT2977, a second-generation HIF-2α inhibitor with an improved PK profile, are ongoing. Clinical trial information: NCT02293980

Inhibition of hypoxia-inducible factor-2α in renal cell carcinoma with belzutifan: a phase 1 trial and biomarker analysis

Hypoxia-inducible factor-2α (HIF-2α) is a transcription factor that frequently accumulates in clear cell renal cell carcinoma (ccRCC), resulting in constitutive activation of genes involved in carcinogenesis. Belzutifan (MK-6482, previously known as PT2977) is a potent, selective small molecule inhibitor of HIF-2α. Maximum tolerated dose, safety, pharmacokinetics, pharmacodynamics and anti-tumor activity of belzutifan were evaluated in this first-in-human phase 1 study (NCT02974738). Patients had advanced solid tumors (dose-escalation cohort) or previously treated advanced ccRCC (dose-expansion cohort). Belzutifan was administered orally using a 3 + 3 dose-escalation design, followed by expansion at the recommended phase 2 dose (RP2D) in patients with ccRCC. In the dose-escalation cohort (n = 43), no dose-limiting toxicities occurred at doses up to 160 mg once daily, and the maximum tolerated dose was not reached; the RP2D was 120 mg once daily. Plasma erythropoietin reductions were observed at all doses; erythropoietin concentrations correlated with plasma concentrations of belzutifan. In patients with ccRCC who received 120 mg once daily (n = 55), the confirmed objective response rate was 25% (all partial responses), and the median progression-free survival was 14.5 months. The most common grade ≥3 adverse events were anemia (27%) and hypoxia (16%). Belzutifan was well tolerated and demonstrated preliminary anti-tumor activity in heavily pre-treated patients, suggesting that HIF-2α inhibition might offer an effective treatment for ccRCC

Phase I/II study of the oral HIF-2 α inhibitor MK-6482 in patients with advanced clear cell renal cell carcinoma (RCC)

611 Background: Hypoxia-inducible factor (HIF)-2α is a transcription factor that is a key oncogenic driver in RCC. MK-6482 is a first-in-class small molecule HIF-2α inhibitor that blocks the heterodimerization of HIF-2α with HIF-1β and induces regression in mouse xenograft RCC models. Methods: Pts with advanced ccRCC who had received at least 1 prior therapy were enrolled in an expansion cohort from the first-in-human phase 1/2 study of MK-6482 in advanced solid tumors (NCT02974738). Pts were administered 120 mg of MK-6482 orally once daily. Primary end point: safety. Key secondary end points: ORR, duration of response (DOR), and PFS. Results: Fifty-five pts were enrolled in the dose expansion cohort. Median (range) number of prior therapies was 3 (1-9); 67% received anti–PD-1 and anti-VEGF agents. Five pts (9%) were favorable risk, 40 (73%) were intermediate risk, and 10 (18%) were poor risk by IMDC criteria. With a median follow-up of 13 mo the most common all-grade, all-cause AEs > 30% were anemia (75%), fatigue (67%), dyspnea (47%), nausea (33%), and cough (31%). Anemia (26%) and hypoxia (15%) were the most common grade 3 AEs. No grade 4/5 drug-related AEs were observed. ORR was 24% with 13 confirmed PRs. Thirty-one pts (56%) had SD, with a disease control rate (CR+PR+SD) of 80%. Thirty-five of 52 (67%) pts with baseline and postbaseline assessments had tumor shrinkage. Median DOR was not reached; 81% of pts had response ≥6 mo per Kaplan-Meier estimate. Sixteen pts (29%) continued treatment beyond 12 mo. By IMDC risk, 2/5 pts with favorable risk had PR (ORR = 40%), 10/40 with intermediate risk had PR (ORR = 25%), and 1/10 with poor risk had PR (ORR = 10%); disease control rate was 100%, 80%, and 70%, respectively. Median PFS for the total population was 11.0 mo; the 12 mo PFS rate was 49%. Median PFS for favorable, intermediate, and poor IMDC risk was 16.5, 11.0, and 6.9 mo, respectively. As of May 15, 2019, 30 pts (55%) discontinued due to PD, 2 (4%) due to AEs. Sixteen pts (29%) had treatment ongoing. Conclusions: MK-6482 is well tolerated with a favorable safety profile and demonstrated promising single-agent activity in heavily pretreated pts with ccRCC across IMDC risk groups. A phase 3 trial in a similar population is planned. Clinical trial information: NCT02974738

Carfilzomib, Lenalidomide, and Dexamethasone for Relapsed Multiple Myeloma.

Background Lenalidomide plus dexamethasone is a reference treatment for relapsed multiple myeloma. The combination of the proteasome inhibitor carfilzomib with lenalidomide and dexamethasone has shown efficacy in a phase 1 and 2 study in relapsed multiple myeloma. Methods We randomly assigned 792 patients with relapsed multiple myeloma to carfilzomib with lenalidomide and dexamethasone (carfilzomib group) or lenalidomide and dexamethasone alone (control group). The primary end point was progression-free survival. Results Progression-free survival was significantly improved with carfilzomib (median, 26.3 months, vs. 17.6 months in the control group; hazard ratio for progression or death, 0.69; 95% confidence interval [CI], 0.57 to 0.83; P=0.0001). The median overall survival was not reached in either group at the interim analysis. The Kaplan-Meier 24-month overall survival rates were 73.3% and 65.0% in the carfilzomib and control groups, respectively (hazard ratio for death, 0.79; 95% CI, 0.63 to 0.99; P=0.04). The rates of overall response (partial response or better) were 87.1% and 66.7% in the carfilzomib and control groups, respectively (P<0.001; 31.8% and 9.3% of patients in the respective groups had a complete response or better; 14.1% and 4.3% had a stringent complete response). Adverse events of grade 3 or higher were reported in 83.7% and 80.7% of patients in the carfilzomib and control groups, respectively; 15.3% and 17.7% of patients discontinued treatment owing to adverse events. Patients in the carfilzomib group reported superior health-related quality of life. Conclusions In patients with relapsed multiple myeloma, the addition of carfilzomib to lenalidomide and dexamethasone resulted in significantly improved progression-free survival at the interim analysis and had a favorable risk-benefit profile. (Funded by Onyx Pharmaceuticals; ClinicalTrials.gov number, NCT01080391 .)