Efficacy/safety of entrectinib in patients (pts) with ROS1-positive (ROS1+) advanced/metastatic NSCLC from the Blood First Assay Screening Trial (BFAST)

LBA9023

Background: Tissue-based biomarker testing remains challenging as tumor biopsies are often inadequate for comprehensive biomarker testing and repeat biopsies can be risky in pts with advanced/metastatic NSCLC. These challenges could be overcome by using blood-based testing to identify the most appropriate targeted therapy. BFAST (NCT03178552) is a global open-label, multicohort trial evaluating the efficacy and safety of selected therapies in pts with advanced/metastatic NSCLC harboring actionable genetic alterations, as identified by next-generation sequencing (NGS) in cell-free DNA (liquid biopsies). We present data from the ROS1+ cohort: this is the first evaluation of entrectinib efficacy in pts identified by prospective blood-based NGS. Methods: In this single-arm analysis, adults (≥18 years) with treatment-naïve measurable stage IIIB/IV NSCLC, identified as ROS1+ by the FoundationOne®Liquid CDx CTA blood-based NGS test, received oral entrectinib 600 mg/day until disease progression (PD), unacceptable toxicity, consent withdrawal or death. Pts with asymptomatic brain metastases at screening were eligible. Tumor scans were performed at baseline and every 8 weeks thereafter for all disease involvement areas (brain imaging not mandated in pts without baseline CNS disease). Primary endpoint: investigator (INV)-assessed objective response rate (ORR; RECIST 1.1). Secondary endpoints: INV-assessed duration of response (DoR) and progression-free survival (PFS); independent review facility (IRF)-assessed ORR, DoR, PFS; overall survival (OS); time to CNS PD; safety. Results: 55 pts with ROS1+ NSCLC identified by blood-based NGS were enrolled and treated with entrectinib. Median age was 56 yrs; 58% of pts were female and 75% had no history of tobacco use. Non-squamous adenocarcinoma was the most common histology (n = 48/55; 87%); 4 pts (7.3%) had baseline CNS disease. Median follow-up: 18.3 months. At data cut-off (26 Nov 2021, n = 54 pts with measurable disease), confirmed ORR was 81.5% (n = 44/54; 95% CI 68.6–90.8) by INV (2 complete responses [CR], 42 partial responses [PR]) and IRF (3 CR, 41 PR). Median DoR was 13.0 months (95% CI 6.3–18.4) by INV and 16.7 months (95% CI 5.6–24.0) by IRF. Median PFS was 12.9 months (95% CI 8.7–18.5) by INV, and 14.8 months (95% CI 7.2–24.0) by IRF. OS data were immature with 20 events (36.4%) recorded. Median time to CNS PD was not reached (INV: 9 events; IRF: 6 events). Most treatment-related adverse events were non-serious with no treatment-related deaths. Conclusion: These data support the clinical value of blood-based NGS as another method to inform clinical decision-making in ROS1+ NSCLC. Pts with ROS1+ NSCLC (by blood-based NGS) treated with entrectinib showed deep and durable responses, consistent with results from entrectinib trials that used tissue-based testing. No new safety signals were observed. Clinical trial information: NCT03178552.

Clinicogenomic real-world data analysis of patients (pts) with KRAS G12C-mutant advanced non-small cell lung cancer (aNSCLC) from the natural history cohort of the Blood First Assay Screening Trial (BFAST)

9023

Background: BFAST (NCT03178552) is a global, multicohort trial of targeted therapies or cancer immunotherapy (CIT) in treatment (tx)-naive aNSCLC. Pts are screened for the study using comprehensive blood-based next-generation sequencing (NGS). In the BFAST natural history cohort, data were collected for pts who received tx or care outside the study’s interventional cohorts. Here, we analyzed the subset of pts whose tumors have KRAS G12C mutations (mut). Methods: Pts eligible for blood-based NGS screening had unresectable aNSCLC, ECOG PS 0-2 and no prior systemic tx for aNSCLC. Pts without tissue samples were eligible. Key genomic and molecular features, including bTMB, PD-L1 and ctDNA concentration; cancer tx; tx response and survival data were collected and analyzed in an exploratory analysis. Results: In the full BFAST screening population through December 2020 (N = 5917), 23% of pts had tumors with any KRAS mut; 9% were KRAS G12C. Pts were enrolled in the natural history cohort from October 2018 to October 2020 (n = 1017); 63 pts had tumors with KRAS G12C mut. Median age was 68 y, 59% were male, 86% had ECOG PS 0-1 and 84% had non-squamous histology. Co-mut in TP53 (60%) and STK11 and/or KEAP1 (25%) were detected; 8% of pts had bTMB ≥16. High PD-L1 expression per local testing was reported in 32% of pts; 38% were not tested. Among pts with 1L tx (n = 50), 50%, 28% and 20% received chemo, CIT or CIT + chemo, respectively, with real-world response rates (CR/PR per physician assessment) of 20%, 29% and 30%, respectively. Of the 13 pts (21%) without documented 1L tx, 7 died ≤3 mo from enrollment. Median OS was 14 mo overall, with differences found between key genomic subsets (Table). Conclusions: BFAST is the first study to identify KRAS G12C mut using blood-based NGS and describe the natural history, clinical characteristics and genomic landscape of this pt subset. Up to 21% of pts may not receive 1L tx. Pts with TP53 co-mut appear to have favorable outcomes, while those with STK11 and/or KEAP1 co-mut appear to have inferior outcomes vs pts without these mut. The lack of PD-L1 testing in many pts indicates a lack of tissue for comprehensive tissue testing, highlighting a potential benefit of blood-based detection of biomarkers, including KRAS G12C. Clinical trial information: NCT03178552. [Table: see text]

Effect of Itraconazole, a Potent CYP3A4 Inhibitor, on the Steady-State Pharmacokinetics of Vemurafenib in Patients With BRAFV600 Mutation-Positive Malignancies

The effects of itraconazole, a strong CYP3A4 inhibitor, on the steady-state pharmacokinetics of vemurafenib were evaluated in a phase 1, multicenter, open-label, fixed-sequence study. Patients with BRAF^V600 mutation-positive metastatic malignancies received oral vemurafenib 960 mg twice daily on days 1 to 20 (period A) and oral vemurafenib 960 mg twice daily with oral itraconazole 200 mg once daily on days 21 to 40 (period B). A mixed-effects analysis of variance model was used to compare log-transformed area under the concentration-time curve during the dosing interval and maximum plasma concentration values for vemurafenib in 8 patients between period B (vemurafenib plus itraconazole) and period A (vemurafenib alone). Multiple doses of itraconazole increased steady-state exposure of vemurafenib by approximately 40%, with geometric least squares mean ratios (period B/period A) of 140% (90% confidence interval, 121-161) for both maximum plasma concentration and area under the concentration-time curve during the dosing interval. There was no apparent increase in incidence or severity of adverse events during coadministration of vemurafenib with itraconazole. In conclusion, coadministration of itraconazole with vemurafenib resulted in a modest increase in exposure of vemurafenib at steady state and was generally well tolerated.

Complement component 5 does not interfere with physiological hemostasis but is essential for Escherichia coli-induced coagulation accompanied by Toll-like receptor 4

There is a close cross-talk between complement, Toll-like receptors (TLRs) and coagulation. The role of the central complement component 5 (C5) in physiological and pathophysiological hemostasis has not, however, been fully elucidated. This study examined the effects of C5 in normal hemostasis and in Escherichia coli-induced coagulation and tissue factor (TF) up-regulation. Fresh whole blood obtained from six healthy donors and one C5-deficient individual (C5D) was anti-coagulated with the thrombin inhibitor lepirudin. Blood was incubated with or without E. coli in the presence of the C5 inhibitor eculizumab, a blocking anti-CD14 monoclonal antibody (anti-CD14) or the TLR-4 inhibitor eritoran. C5D blood was reconstituted with purified human C5. TF mRNA was measured by quantitative polymerase chain reaction (qPCR) and monocyte TF and CD11b surface expression by flow cytometry. Prothrombin fragment 1+2 (PTF1·2) in plasma and microparticles exposing TF (TF-MP) was measured by enzyme-linked immunosorbent assay (ELISA). Coagulation kinetics were analyzed by rotational thromboelastometry and platelet function by PFA-200. Normal blood with eculizumab as well as C5D blood with or without reconstitution with C5 displayed completely normal biochemical hemostatic patterns. In contrast, E. coli-induced TF mRNA and TF-MP were significantly reduced by C5 inhibition. C5 inhibition combined with anti-CD14 or eritoran completely inhibited the E. coli-induced monocyte TF, TF-MP and plasma PTF1·2. Addition of C5a alone did not induce TF expression on monocytes. In conclusion, C5 showed no impact on physiological hemostasis, but substantially contributed to E. coli-induced procoagulant events, which were abolished by the combined inhibition of C5 and CD14 or TLR-4.

Allogeneic stem cell transplantation as initial salvage for patients with acute myeloid leukemia refractory to high-dose cytarabine-based induction chemotherapy

Outcomes of patients with acute myeloid leukemia (AML) who are refractory to high-dose Cytarabine (HiDAC)-based induction are dismal. Allogeneic hematopoietic stem cell transplantation (AHSCT) as initial salvage may be effective and potentially superior to conventional salvage chemotherapy. Eighteen percent (285 of 1597) of AML patients were primary refractory to HiDAC-based regimens at the MD Anderson Cancer Center between 1995 and 2009. AHSCT was the initial salvage in 28 cases. These patients were compared against 149 patients who received salvage chemotherapy, but never received AHSCT. Patients receiving salvage chemotherapy were older, had higher bone marrow blasts percentage, and higher incidence of unfavorable cytogenetics (P < 0.001). Median time from induction to AHSCT was 76 days. Objective response was achieved in 23 of 28 patients (82%) undergoing AHSCT. The incidence of grade III/IV acute and chronic graft versus-host-disease was 11% and 29%, respectively. Median follow up for living patients is 80 months. Median overall survival (OS) was 15.7 months and 2.9 months for AHSCT and chemotherapy, respectively (P < 0.001); the 3-year OS rates were 39% and 2%, respectively. ASHCT as initial salvage therapy was identified as an independent prognostic factor for survival in multivariate analysis (HR = 3.03; P < 0.001). Initial salvage therapy with AHSCT in patients with primary HiDAC refractory AML is feasible and may yield superior outcomes to salvage chemotherapy.

Interim results of a phase I/II randomized study of clofarabine, idarubicin, and cytarabine (CIA) versus fludarabine, idarubicin, and cytarabine (FIA) for newly diagnosed or relapsed patients (pts) with acute myeloid leukemia (AML)

6607

Background: Outcomes of pts with AML remain suboptimal. The addition of cladribine to 3+7 has been shown to improve complete remission (CR) rates and 3-year survival. The aim of this study was to assess the efficacy and safety of idarubicin + cytarabine (IA, idarubicin 10 mg/m2 on days 1-3, cytarabine 1 g/m2 on days 1-5) combined with two other nucleoside analogs, clofarabine (C) or fludarabine (F), in pts with newly diagnosed and relapsed/refractory (RR) AML. Methods: Pts with newly diagnosed or RR non-M3 AML with normal organ function were eligible. Pts with RR disease were treated in the phase I portion defining the MTD of C. The starting dose of C was 15 mg/m2 with doses escalating to 25 mg/m2 on days 1-5 in subsequent cohorts. During phase II, patients were randomized in a Bayesian design to C at the MTD with IA or fludarabine (F) at 30 mg/m2 on days 1-5 with IA. Up to 6 consolidation cycles were planned according to an attenuated schedule using the same drugs. Dose adjustments were made for elderly pts or pts with poor PS. Results: 9 pts were enrolled in the phase I portion. The overall response rate (ORR) in this group was 44%. DLT were observed at C 20 mg/m2 and included hand/foot syndrome (HFS), elevated bilirubin, and prolonged myelosuppression. The MTD was 15 mg/m2 on days 1-5. 50 evaluable pts were enrolled (16 newly diagnosed, 34 RR) in the phase II. In the frontline cohort, median age was similar in both groups (C 56, F 55), as were the cytogenetic profiles. The CR rate was 100% in both groups (9 CIA, 7 FIA). Detailed efficacy information can be found in the Table. More than half of the RR cohort were receiving therapy as salvage 2 or higher, and most had short first CR durations. Notable toxicities included elevated liver function tests for both groups, and HFS in the C group. There were 4 deaths on study, though most pts were receiving therapy as second salvage and were over the age of 60. Conclusions: CIA and FIA are effective regimens for newly diagnosed or RR AML with manageable toxicity profiles. The ORR were 100% and 32% for newly diagnosed and RR AML pts, respectively, with low early mortality rates. The study is ongoing.

Allogenic stem cell transplant (ASCT) as initial salvage for patients (pts) with acute myeloid leukemia (AML) refractory to high-dose cytarabine-based induction chemotherapy

6544

Background: Outcomes of pts with AML who are refractory to High-dose Cytarabine (HiDAC) based induction are dismal. ASCT as initial salvage may be effective and potentially superior to repeat induction with combination chemotherapies in such pts. Methods: 1597 AML pts were treated with HiDAC-based induction at MD Anderson Cancer Center between 1995 and 2009. 285 primary refractory pts were identified. 28 (10%) of these underwent ASCT as initial salvage and were reviewed. Results: Median age was 56 years (36 to 77) and 50% were males. Median ECOG PS was 1 (0-2). Antecedent hematological disorders were present in 14 pts (50%). Median white cell count, hemoglobin, platelet count and bone marrow (BM) blast percentage at diagnosis were 3.5 x 109/l (0.6 to 73.6), 7.8 g/l (6.5 to 11.4), 44 x 109/l (9 to 615), and 43% (6-82), respectively. 9 pts (32%) had complex cytogenetics. FLT3 mutations were identified in 2 (15%) of 13 evaluated pts. All pts were refractory to HiDAC-based induction. HiDAC was combined with an anthracycline in 16 pts (57%) and non-anthracycline in 12 pts (43%). Median time from induction to ASCT was 76 days (28 to 184). Median BM blast and peripheral blast at ASCT were 28% (3 to 82) and 4% (0 to 41). 21 pts (75%) had matched related donors (18 sibling and 3 haploidentical) and 7 (25%) had matched unrelated donors. Conditioning regimens were melphalan-based, busulfan-based, fludarabine-based or others in 7 (25%), 10 (36%), 8 (29%) and 3 pts (10%); respectively. Complete remission (CR) was achieved in 23 of 28 pts undergoing ASCT (CR = 82%) with median time to CR of 31 days (26 to 134). 12 pts relapsed with median time to relapse of 5 months (2 to 19). 8 pts remain alive with median follow up of 80 months (28 to 118). Median overall survival (OS) for the entire group is 20 months (5 to 118). In historical series of pts with AML refractory to HiDAC-based induction, salvage chemotherapies induced CR rates of 22% with median OS of 4 months. Conclusions: Initial salvage with allogenic SCT is feasible and yields superior outcomes to salvage chemotherapy in primary HiDAC refractory AML pts. Randomized studies are warranted to further explore this treatment option.

FLT3 mutations in myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML)

6597

Background: FLT3 mutations occur in one third of acute myeloid leukemia (AML) patients (pts) and predict poor outcome. The incidence and impact of FLT3 in MDS/ CMML is unknown. Methods: We conducted a retrospective review at MDACC to identify FAB MDS/ CMML pts with FLT3 mutations at diagnosis. Results: From 1996 to 2010; 2052 MDS/ CMML pts had mutation analysis. 45 (2.2%) had FLT3 mutations (internal tandem duplication-ITD or D835) at diagnosis. 29 pts had MDS and 16 had CMML. Median (Med) age was 64 years (21 to 83) and 69% were males. FAB groups: 3 pts with refractory anemia (RA), 11 pts with refractory anemia-excess blasts (RAEB), 18 pts with refractory anemia-excess blasts in transformation (RAEB-T) and 13 pts with CMML. IPSS: 3 in Low (7%), 16 in Int-1 (36%), 11 in Int-2 (24%), and 15 in High (33%). Med white count, hemoglobin, platelet count and marrow blast percent at diagnosis were 5.2 x 109/l (1.2 to 211), 10.0 g/l (6.8 to 14.9), 78 x 109/l (8 to 429), and 14% (1 to 28), respectively. FLT3 ITD and FLT3 D835 mutations were present in 32 (71%) and 13 pts (29%), respectively. Karyotype was diploid in 30 (66%); -5/-7 in 5 (11%), 11q in 1 (2%), and others in 9 pts (19%). All 5 pts with -5/ -7 had the ITD mutation. Concurrent mutations were identified in RAS, NPM1 and C-Kit in 6 (13%), 3 (7%) and 1 (2%) pt, respectively. Med overall survival (OS) for FLT3 pts was 15 months compared to 17 months for non FLT3 pts (P=0.9). 18 pts had RAEB-T: 13 (72%) received AraC-based therapy and 3 (17%) received hypomethylating therapy (HMT) with complete remission (CR) in 14 pts (78%). 14 pts had RA/ RAEB: 5 (36%) received AraC-based therapy and 7 (50%) received HMT with CR in 5 (37%) and hematological improvement (HI) in 4 (28%). 13 pts had CMML: 4 (31%) received AraC-based therapy and 6 (46%) received HMT with CR in 3 (23%) and HI in 3 (23%). Repeat FLT3 was available on 16 pts achieving any response and was absent/ decreased in 14 (88%), stable in 1 (6%) and increased in 1 (6%). Notably, the 14 pts with absent/ decreased FLT3 had med OS of 27 months versus 12 months for remaining group (P=0.004). Conclusions: FLT3 occurs in MDS/ CMML at a lower frequency than AML and does not predict poor outcome. Pts who achieve absent/ decreased FLT3 seem to have significantly improved overall survival.

Prostatic specific antigen and prostatic acid phosphatase in the monitoring and staging of patients with prostatic cancer

Serum prostatic specific antigen and prostatic acid phosphatase levels were measured retrospectively and evaluated in 357 men with benign prostatic hypertrophy and in 209 men with various stages of prostatic carcinoma. Although prostatic specific antigen values were elevated in 21 per cent of the patients with benign prostatic hypertrophy, the elevations usually were low and did not interfere with clinical interpretation. Prostatic specific antigen was elevated in 98 per cent of 86 men with active stage D2 disease; in 22 per cent of the men prostatic specific antigen was the only elevated marker. In contrast, prostatic acid phosphatase was the only elevated marker in 1 per cent of the patients with stage D2 disease and neither marker was elevated in 2 per cent. Among 74 patients in whom prostatic specific antigen and prostatic acid phosphatase determinations were made before radical prostatectomy, prostatic specific antigen was elevated substantially (greater than 10 ng. per ml.) in 59 per cent (26 of 44) with extracapsular disease and in only 7 per cent (2 of 30) without extracapsular disease. More importantly, of those 28 patients with substantially elevated prostatic specific antigen levels 26 (93 per cent) had extracapsular disease. Serial serum measurements showed that prostatic specific antigen either reflected or predicted clinical status in more than 97 per cent of the patients. We conclude that prostatic specific antigen is an excellent serum tumor marker for monitoring patients with prostatic carcinoma and that it surpasses prostatic acid phosphatase in this regard. Prostatic specific antigen also may be useful in staging prostatic carcinoma and it may change our attitudes significantly about the therapeutic responses to this cancer.