Limited efficacy of APRIL CAR in patients with multiple myeloma indicate challenges in the use of natural ligands for CAR T-cell therapy

BACKGROUND

We used a proliferating ligand (APRIL) to construct a ligand-based third generation chimeric antigen receptor (CAR) able to target two myeloma antigens, B-cell maturation antigen (BCMA) and transmembrane activator and CAML interactor.

METHODS

The APRIL CAR was evaluated in a Phase 1 clinical trial (NCT03287804, AUTO2) in patients with relapsed, refractory multiple myeloma. Eleven patients received 13 doses, the first 15×10⁶ CARs, and subsequent patients received 75,225,600 and 900×10⁶ CARs in a 3+3 escalation design.

RESULTS

The APRIL CAR was well tolerated. Five (45.5%) patients developed Grade 1 cytokine release syndrome and there was no neurotoxicity. However, responses were only observed in 45.5% patients (1×very good partial response, 3×partial response, 1×minimal response). Exploring the mechanistic basis for poor responses, we then compared the APRIL CAR to two other BCMA CARs in a series of in vitro assays, observing reduced interleukin-2 secretion and lack of sustained tumor control by APRIL CAR regardless of transduction method or co-stimulatory domain. There was also impaired interferon signaling of APRIL CAR and no evidence of autoactivation. Thus focusing on APRIL itself, we confirmed similar affinity to BCMA and protein stability in comparison to BCMA CAR binders but reduced binding by cell-expressed APRIL to soluble BCMA and reduced avidity to tumor cells. This indicated either suboptimal folding or stability of membrane-bound APRIL attenuating CAR activation.

CONCLUSIONS

The APRIL CAR was well tolerated, but the clinical responses observed in AUTO2 were disappointing. Subsequently, when comparing the APRIL CAR to other BCMA CARs, we observed in vitro functional deficiencies due to reduced target binding by cell-expressed ligand.

A phase I, pharmacokinetic and pharmacodynamic study of GSK2256098, a focal adhesion kinase inhibitor, in patients with advanced solid tumors

BACKGROUND

Focal adhesion kinase (FAK) is important in cancer growth, survival, invasion, and migration. The purpose of this study was to determine the maximum tolerated dose (MTD), safety, pharmacokinetics (PK), and pharmacodynamics (PD) of the FAK inhibitor, GSK2256098, in cancer patients.

PATIENTS AND METHODS

The dose of GSK2256098 was escalated, in cohorts of patients with advanced cancer, from 80 to 1500 mg, oral twice daily (BID), until the MTD was determined. Serial blood samples were obtained from all patients, and the PK was determined. Paired tumor biopsies were obtained in select patients, and the level of phospho-FAK (pFAK) was determined.

RESULTS

Sixty-two patients (39 males, 23 females; median age 61 y.o., range 21-84) received GSK2256098. Dose-limiting toxicities of grade 2 proteinuria (1000 mg BID), grade 2 fatigue, nausea, vomiting (1250 mg BID), and grade 3 asthenia and grade 2 fatigue (1500 mg BID) were reported with the MTD identified as 1000 mg BID. The most frequent adverse events (AEs) were nausea (76%), diarrhea (65%), vomiting (58%), and decreased appetite (47%) with the majority of AEs being grades 1-2. The PK was generally dose proportional with a geometric mean elimination half-life range of 4-9 h. At the 750, 1000, and 1500 mg BID dose levels evaluated, the pFAK, Y397 autophosphorylation site, was reduced by ∼80% from baseline. Minor responses were observed in a patient with melanoma (-26%) and three patients with mesothelioma (-13%, -15%, and -17%). In the 29 patients with recurrent mesothelioma, the median progression-free survival was 12 weeks with 95% CI 9.1, 23.4 weeks (23.4 weeks merlin negative, n = 14; 11.4 weeks merlin positive, n = 9; 10.9 weeks merlin status unknown, n = 6).

CONCLUSIONS

GSK2256098 has an acceptable safety profile, has evidence of target engagement at doses at or below the MTD, and has clinical activity in patients with mesothelioma, particularly those with merlin loss.

EGFR Fusions as Novel Therapeutic Targets in Lung Cancer

Here, we report that novel epidermal growth factor receptor (EGFR) gene fusions comprising the N-terminal of EGFR linked to various fusion partners, most commonly RAD51, are recurrent in lung cancer. We describe five patients with metastatic lung cancer whose tumors harbored EGFR fusions, four of whom were treated with EGFR tyrosine kinase inhibitors (TKI) with documented antitumor responses. In vitro, EGFR-RAD51 fusions are oncogenic and can be therapeutically targeted with available EGFR TKIs and therapeutic antibodies. These results support the dependence of EGFR-rearranged tumors on EGFR-mediated signaling and suggest several therapeutic strategies for patients whose tumors harbor this novel alteration.

SIGNIFICANCE

We report for the first time the identification and therapeutic targeting of EGFR C-terminal fusions in patients with lung cancer and document responses to the EGFR inhibitor erlotinib in 4 patients whose tumors harbored EGFR fusions. Findings from these studies will be immediately translatable to the clinic, as there are already several approved EGFR inhibitors. Cancer Discov; 6(6); 601-11. ©2016 AACR.See related commentary by Paik, p. 574This article is highlighted in the In This Issue feature, p. 561.

Phase I Dose-Escalation Study of JNJ-42756493, an Oral Pan–Fibroblast Growth Factor Receptor Inhibitor, in Patients With Advanced Solid Tumors

Purpose

JNJ-42756493 is an orally administered pan-fibroblast growth factor receptor (FGFR) tyrosine kinase inhibitor. This first-in-human study evaluates the safety, pharmacokinetics, and pharmacodynamics and defines the recommended phase II dose (RP2D) of JNJ-42756493.

Patients and Methods

Eligible patients with advanced solid tumors received escalating doses of JNJ-42756493 from 0.5 to 12 mg administered continuously daily or JNJ-42756493 10 or 12 mg administered intermittently (7 days on/7 days off).

Results

Sixty-five patients were enrolled. The most common treatment-emergent adverse events included hyperphosphatemia (65%), asthenia (55%), dry mouth (45%), nail toxicity (35%), constipation (34%), decreased appetite (32%), and dysgeusia (31%). Twenty-seven patients (42%) experienced grade ≥ 3 treatment-emergent adverse events, and one dose-limiting toxicity of grade 3 ALT elevation was observed at 12 mg daily. Maximum-tolerated dose was not defined. Nine milligrams daily was considered as the initial RP2D; however, tolerability was improved with intermittent schedules, and 10 mg administered on a 7-days-on/7-days-off schedule was considered the final RP2D. Pharmacokinetics were linear, dose proportional, and predictable, with a half-life of 50 to 60 hours. Dose-dependent elevations in serum phosphate, a manifestation of pharmacodynamic effect, occurred in all patients starting at 4 mg daily. Among 23 response-evaluable patients with tumor FGFR pathway alterations, four confirmed responses and one unconfirmed partial response were observed in patients with glioblastoma and urothelial and endometrial cancer (all with FGFR2 or FGFR3 translocations); 16 patients had stable disease.

Conclusion

JNJ-42756493 administered at 10 mg on a 7-days-on/7-days-off schedule achieved exposures at which clinical responses were observed, demonstrated pharmacodynamic biomarker activity, and had a manageable safety profile.