Bernard M. Fine

Molecular Biomarker Analyses Using Circulating Tumor Cells

Background Evaluation of cancer biomarkers from blood could significantly enable biomarker assessment by providing a relatively non-invasive source of representative tumor material. Circulating Tumor Cells (CTCs) isolated from blood of metastatic cancer patients hold significant promise in this regard. Methodology/Principal Findings Using spiked tumor-cells we evaluated CTC capture on different CTC technology platforms, including CellSearch® and two biochip platforms, and used the isolated CTCs to develop and optimize assays for molecular characterization of CTCs. We report similar performance for the various platforms tested in capturing CTCs, and find that capture efficiency is dependent on the level of EpCAM expression. We demonstrate that captured CTCs are amenable to biomarker analyses such as HER2 status, qRT-PCR for breast cancer subtype markers, KRAS mutation detection, and EGFR staining by immunofluorescence (IF). We quantify cell surface expression of EGFR in metastatic lung cancer patient samples. In addition, we determined HER2 status by IF and FISH in CTCs from metastatic breast cancer patients. In the majority of patients (89%) we found concordance with HER2 status from patient tumor tissue, though in a subset of patients (11%), HER2 status in CTCs differed from that observed in the primary tumor. Surprisingly, we found CTC counts to be higher in ER+ patients in comparison to HER2+ and triple negative patients, which could be explained by low EpCAM expression and a more mesenchymal phenotype of tumors belonging to the basal-like molecular subtype of breast cancer. Conclusions/Significance Our data suggests that molecular characterization from captured CTCs is possible and can potentially provide real-time information on biomarker status. In this regard, CTCs hold significant promise as a source of tumor material to facilitate clinical biomarker evaluation. However, limitations exist from a purely EpCAM based capture system and addition of antibodies to mesenchymal markers could further improve CTC capture efficiency to enable routine biomarker analysis from CTCs.

Evaluation of Circulating Tumor Cells and Circulating Tumor DNA in Non–Small Cell Lung Cancer: Association with Clinical Endpoints in a Phase II Clinical Trial of Pertuzumab and Erlotinib

Purpose: Elevated levels or increases in circulating tumor cells (CTC) portend poor prognosis in patients with epithelial cancers. Less is known about CTCs as surrogate endpoints or their use for predictive biomarker evaluation. This study investigated the utility of CTC enumeration and characterization using the CellSearch platform, as well as mutation detection in circulating tumor DNA (ctDNA), in patients with advanced non–small cell lung cancer (NSCLC). Experimental Design: Forty-one patients were enrolled in a single-arm phase II clinical trial of erlotinib and pertuzumab. Peripheral blood was analyzed for CTC enumeration, EGFR expression in CTCs, and detection of oncogenic mutations in CTCs and ctDNA. Changes in CTC levels were correlated with 2[18F]fluoro-2-deoxy-d-glucose–positron emission tomographic (FDG-PET) and computed tomographic (CT) imaging and survival endpoints. Results: CTCs were detected (≥1 CTC) at baseline in 78% of patients. Greater sensitivity for mutation detection was observed in ctDNA than in CTCs and detected mutations were strongly concordant with mutation status in matched tumor. Higher baseline CTC counts were associated with response to treatment by Response Evaluation Criteria in Solid Tumors (RECIST, P = 0.009) and decreased CTC counts upon treatment were associated with FDG-PET and RECIST response (P = 0.014 and P = 0.019) and longer progression-free survival (P = 0.050). Conclusion: These data provide evidence of a correlation between decreases in CTC counts and radiographic response by either FDG-PET or RECIST in patients with advanced NSCLC. These findings require prospective validation but suggest a potential role for using CTC decreases as an early indication of response to therapy and ctDNA for real-time assessment of mutation status from blood. Clin Cancer Res; 18(8); 2391–401. ©2012 AACR.

Changes in 18F-Fluorodeoxyglucose and 18F-Fluorodeoxythymidine Positron Emission Tomography Imaging in Patients with Non–Small Cell Lung Cancer Treated with Erlotinib

Purpose: Assessing clinical activity of molecularly targeted anticancer agents, especially in the absence of tumor shrinkage, is challenging. To evaluate on-treatment 18F-fluorodeoxyglucose (FDG) and/or 18F-fluorodeoxythymidine (FLT) positron emission tomography (PET) for this purpose, we conducted a prospective multicenter trial assessing PET response rates and associations with progression-free (PFS) and overall survival (OS) in 2nd/3rd-line non–small-cell lung cancer patients treated with erlotinib. Experimental Design: PET/computed tomography (CT) scans were conducted at baseline, day (d)14 and d56 after the first daily erlotinib dose, with diagnostic CT at baseline and d56 (all scans centrally reviewed). PET partial metabolic response (PMR) was defined as a mean decrease (in ≤5 lesions/patient) of 15% or more maximum standardized uptake value. PFS was investigator-determined. Results: Of 74 erlotinib-treated patients, 51 completed all imaging assessments through d56; 13 of 51 (26%) FDG-evaluable patients had PMR at d14, as did 9 of 50 (18%) FLT-evaluable patients. Four (7.8%) showed partial responses (PR) by d56 CT; all 4 had PMR by d14 FDG-PET with 3 PMRs by d14 FLT-PET. Three of the 4 patients with CT PR had evaluable archival tumor tissue; all 3 had epidermal growth factor receptor mutations. D14 and d56 PMRs by FDG or FLT were associated with improved PFS; HRs for PET responders versus nonresponders were 0.3 to 0.4. D14 FDG-PET PMR was associated with improved OS (P = 0.03) compared with FDG-PET nonresponders. Conclusion: Early (d14) FDG-PET PMR is associated with improved PFS and OS, even in the absence of subsequent Response Evaluation Criteria in Solid Tumors response. These data support inclusion of FDG-PET imaging in clinical trials testing novel targeted therapies, particularly those with anticipated cytostatic effects. Clin Cancer Res; 17(10); 3304–15. ©2011 AACR.

ImmunoPET with Anti-Mesothelin Antibody in Patients with Pancreatic and Ovarian Cancer before Anti-Mesothelin Antibody-Drug Conjugate Treatment

Purpose: Mesothelin (MSLN) is frequently overexpressed in pancreatic and ovarian cancers, making it a potential drug target. We performed an 89Zr-PET imaging study with MMOT0530A, a MSLN antibody, in conjunction with a phase I study with the antibody–drug conjugate DMOT4039A, containing MMOT0530A bound to MMAE. The aim was to study antibody tumor uptake, whole-body distribution, and relation between uptake, response to treatment, and MSLN expression. Experimental Design: Before DMOT4039A treatment, patients received 37 MBq 89Zr-MMOT0530A followed by PET/CT imaging 2, 4, and 7 days postinjection. Tracer uptake was expressed as standardized uptake value (SUV). MSLN expression was determined with immunohistochemistry (IHC) on archival tumor tissue. Results: Eleven patients were included, 7 with pancreatic and 4 with ovarian cancer. IHC MSLN expression varied from absent to strong. Suitable tracer antibody dose was 10 mg MMOT0530A and optimal imaging time was 4 and 7 days postinjection. Tumor tracer uptake occurred in 37 lesions with mean SUVmax of 13.1 (±7.5) on PET 4 days postinjection, with 11.5 (±7.5) in (N = 17) pancreatic and 14.5 (±8.7) in (N = 20) ovarian cancer lesions. Within patients, a mean 2.4-fold (±1.10) difference in uptake between tumor lesions existed. Uptake in blood, liver, kidneys, spleen, and intestine reflected normal antibody distribution. Tracer tumor uptake was correlated to IHC. Best response to DMOT4039A was partial response in one patient. Conclusions: With 89Zr-MMOT0530A-PET, pancreatic and ovarian cancer lesions as well as antibody biodistribution could be visualized. This technique can potentially guide individualized antibody-based treatment. Clin Cancer Res; 22(7); 1642–52. ©2015 AACR.

Pertuzumab and Erlotinib in Patients With Relapsed Non-Small Cell Lung Cancer: A Phase II Study Using 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Imaging

BACKGROUND Combination blockade of human epidermal growth factor receptor (HER) family signaling may confer enhanced antitumor activity than single-agent blockade. We performed a single-arm study of pertuzumab, a monoclonal antibody that inhibits HER2 dimerization, and erlotinib in relapsed non-small cell lung cancer (NSCLC). METHODS Patients received pertuzumab (840-mg loading dose and 420-mg maintenance intravenously every 3 weeks) and erlotinib (150-mg or 100-mg dose orally, daily). The primary endpoint was response rate (RR) by 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) at day 56 in all patients and those with EGFR wild-type tumors. RESULTS Of 41 patients, 28 (68.3%) experienced treatment-related grade ≥3 adverse events, including pneumatosis intestinalis (3 patients), resulting in early cessation of enrollment. Tissue samples from 32 patients showed mutated EGFR status in 9 of 41 (22%) and wild-type EGFR in 23 of 41 (56%). The FDG-PET RR for patients with assessments at day 56 was 19.5% in all patients (n = 41) and 8.7% in patients with wild-type EGFR NSCLC (n = 23). Investigator-assessed computed tomography RR at day 56 was 12.2%. CONCLUSION FDG-PET suggests that pertuzumab plus erlotinib is an active combination, but combination therapy was poorly tolerated, which limits its clinical applicability. More research is warranted to identify drug combinations that disrupt HER receptor signaling but that exhibit improved tolerability profiles.

Decision Making for a Companion Diagnostic in an Oncology Clinical Development Program

The decision to incorporate the specific evaluation of a candidate companion diagnostic (CDx) in a clinical development plan (CDP) is often difficult and is exacerbated by the lack of relevant decision tools. In this article, we discuss a novel methodology to assess the probability of technical success (PTS) of a CDP that adequately evaluates a CDx compared with a CDP that does not. We propose splitting the PTS into subjective (biological uncertainty) and quantitative (clinical uncertainty) components, assessing each separately and then combining them in a decision theoretic manner to obtain an overall success probability of a CDP with and without a CDx.

Peripheral neuropathy with microtubule inhibitor containing antibody drug conjugates: Challenges and perspectives in translatability from nonclinical toxicology studies to the clinic.

Antibody drug conjugates (ADC) consist of potent cytotoxic drugs conjugated to antibodies via chemical linkers, which enables specific targeting of tumor cells while reducing systemic exposure to the cytotoxic drug and improving the therapeutic window. The valine citrulline monomethyl auristatin E (vcMMAE, conventional linker-drug) ADC platform has shown promising clinical activity in several cancers, but peripheral neuropathy (PN) is a frequent adverse event leading to treatment discontinuation and dose reduction. This was not predicted based on nonclinical toxicology studies in monkeys or rats treated with vcMMAE ADCs. We evaluated four hypotheses for the lack of translatability of PN with vcMMAE ADCs: 1) species differences in exposure; 2) insensitivity of animal models; 3) species differences in target biology and other vcMMAE ADC properties in peripheral nerves and 4) increased susceptibility of patient population. The result of this hypothesis-based approach identified opportunities to improve the predictivity of PN in our animal models by increasing duration of exposure and adding an expanded neurohistopathology assessment of peripheral nerves. The utility of a predictive animal model would be to provide possible mitigation strategies in the clinic with vcMMAE ADCs and help to screen the next generation microtubule inhibitor (MTI) ADCs for reduced PN.

Platform model describing pharmacokinetic properties of vc-MMAE antibody–drug conjugates

Antibody–drug conjugates (ADCs) developed using the valine-citrulline-MMAE (vc-MMAE) platform, consist of a monoclonal antibody (mAb) covalently bound with a potent anti-mitotic toxin (MMAE) through a protease-labile vc linker. Recently, clinical data for a variety of vc-MMAE ADCs has become available. The goal of this analysis was to develop a platform model that simultaneously described antibody-conjugated MMAE (acMMAE) pharmacokinetic (PK) data from eight vc-MMAE ADCs, against different targets and tumor indications; and to assess differences and similarities of model parameters and model predictions, between different compounds. Clinical PK data of eight vc-MMAE ADCs from eight Phase I studies were pooled. A population PK platform model for the eight ADCs was developed, where the inter-compound variability (ICV) was described explicitly, using the third random effect level (ICV), and implemented using LEVEL option of NONMEM 7.3. The PK was described by a two-compartment model with time dependent clearance. Clearance and volume of distribution increased with body weight; volume was higher for males, and clearance mildly decreased with the nominal dose. Michaelis–Menten elimination had only minor effect on PK and was not included in the model. Time-dependence of clearance had no effect beyond the first dosing cycle. Clearance and central volume were similar among ADCs, with ICV of 15 and 5%, respectively. Thus, PK of acMMAE was largely comparable across different vc-MMAE ADCs. The model may be applied to predict PK-profiles of vc-MMAE ADCs under development, estimate individual exposure for the subsequent PK–pharmacodynamics (PD) analysis, and project optimal dose regimens and PK sampling times.

Abstract CT017: First-in-human PET imaging with the PD-L1 antibody 89Zr-atezolizumab

Background: Programmed death-ligand 1 (PD-L1) expression has been associated with response to PD-1/PD-L1 inhibition, but responses are also seen in patients with PD-L1 negative tumors when assessed immunohistochemically (IHC) with various antibodies. To help understand these findings, we performed a first-in-human positron emission tomography (PET) imaging study with the anti-PD-L1 antibody atezolizumab labeled with zirconium-89 (89Zr) prior to treatment with atezolizumab to assess normal organ distribution and evaluate tumor tracer uptake in relation to PD-L1 IHC in archival and post-tracer tumor specimen and ultimately to treatment response. Methods: Patients with locally advanced or metastatic non-small cell lung cancer (NSCLC), bladder cancer (BC) or triple-negative breast cancer (TNBC) received 10 mg unlabeled atezolizumab plus 37 MBq 89Zr-atezolizumab (~1 mg) followed by up to 4 PET scans (1 hour, days 2, 4 and 7 post-injection (pi)). Next, after obtaining a tumor biopsy for PD-L1 IHC 8-10 days after tracer injection, patients received atezolizumab (1200 mg) i.v. once every 3 weeks until disease progression (NCT02453984 and NCT02478099). Response was assessed every 6 weeks with RECIST1.1. Normal organ tracer uptake was calculated as percentage of the injected dose/kg (%ID/kg) 4 and 7 days pi, tumor tracer uptake as maximum standardized uptake value (SUVmax) and %ID/kg 7 days pi. Tumor biopsy PD-L1 expression was assessed in tumor cells (TC) and tumor infiltrating immune cells (IC) by HistoGeneX IHC with the SP142 assay (Ventana). Results: In this ongoing trial, 16/25 patients completed the PET series and received atezolizumab at least until the first response assessment. The median follow-up of these patients is 16 weeks (6-40+, NSCLC=6, BC=8, TNBC=2). The highest normal organ 89Zr-atezolizumab uptake was seen in the spleen (16.3±3.6 %ID/kg 4 days and 17.9±3.6 %ID/kg 7 days pi), and uptake in other lymphatic organs (single normal lymph nodes and tonsil) and sites of (chronic) inflammation (e.g. chronic sinusitis and bursitis) were detected. Uptake in liver, kidney and intestine was similar to other antibodies with 7.3±1.6, 5.5±2.0 and 4.7±2.4 %ID/kg, respectively, 7 days pi. Tumor SUVmax ranged between 1.6 and 46.0 (1.8-12.4 %ID/kg), with an up to 9-fold difference within patients, and 4-fold difference between patients. In 4 biopsied lesions with IC/TC 0, 89Zr-atezolizumab uptake calculated as SUVmax was 10.0±3.6 (7.1±1.6 %ID/kg). At this time only 4 biopsies had a IHC score of 2+ on either IC or TC, and there were no biopsies with a score of 3+, limiting the ability to determine correlation of PD-L1 IHC to imaging data. Conclusion: 89Zr-atezolizumab imaging showed high uptake in normal spleen, other normal lymphoid organs and regions of inflammation. Uptake in tumor lesions was heterogeneous within and between patients and even PD-L1 IHC 0 tumors showed clear tracer uptake. Citation Format: Frederike Bensch, Elly van der Veen, Annelies Jorritsma, Marjolijn Lub-de Hooge, Ronald Boellaard, Sjoukje Oosting, Carolien Schroder, Jeroen Hiltermann, Anthonie van der Wekken, Harry Groen, Bernard Fine, Nathan McKnight, Sandra Sanabria Bohorquez, Simon Williams, Luisa Veronese, Christoph Mancao, Adrienne H. Brouwers, Elisabeth de Vries. First-in-human PET imaging with the PD-L1 antibody 89Zr-atezolizumab [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT017. doi:10.1158/1538-7445.AM2017-CT017

Abstract 4310: Predictive biomarkers of tumor sensitivity to STEAP1 antibody-drug conjugate (ADC) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC)

ADCs hold promise for enhancing the therapeutic index of cytotoxics. STEAP1 is overexpressed in mCRPC and is the target of an ADC currently under clinical development. To identify pts most likely to benefit from the ADC, we explored STEAP1 expression as a predictive biomarker in tumor tissue using a CLIA-certified IHC assay, and on circulating tumor cells (CTCs) in blood using the CellSearch and EPIC platforms. Sixty pts with progressive mCRPC received doses ranging from 0.3 to 2.8 mg/kg once every three weeks. Response was defined as a ≥50% decline in PSA from baseline, and time on study for >6 months was consistent with continued clinical benefit. At doses of ≥2 mg/kg, the response rate (RR) was 10/45 (22%, 95% CI 9.9-34.1) and was highest in the STEAP1 IHC 3+ group, as was the fraction of patients who remained on study for >6 months. At ≥2 mg/kg, 20/45 pts (44%, 95% CI 29.5-58.5) had unfavorable CTC counts of ≥5/7.5mL at baseline and were considered evaluable. After treatment, conversions from unfavorable to favorable CTC counts of An immuno-fluorescence-based assay developed to measure STEAP1 expression levels on CTCs showed readily detectable signal in 18/42 samples (43%, 95% CI 28-58), with a range from 1-56% of STEAP1-positive CTCs per case. After treatment, a decrease in the fraction of patients with STEAP1-positive and an increase in the STEAP1-negative CTCs was observed compared to baseline (see Table). We are prospectively selecting pts with STEAP1 IHC 2+/3+ tumors and assessing STEAP1 levels on CTCs in an ongoing Ph1 expansion study with the goal of developing a companion diagnostic to enrich for mCRPC pts most likely to benefit from treatment with the STEAP1 ADC. Citation Format: Daniel C. Danila, Howard I. Scher, Edith Szafer-Glusman, Amrita Herkal, Rebecca Suttmann, Martin Fleisher, Nicole A. Schreiber, Kristen Curtis, Houston Gilbert, Daniel Maslyar, Bernard Fine, Ron Firestein, Michael Mamounas, Mark R. Lackner, Omar Kabbarah. Predictive biomarkers of tumor sensitivity to STEAP1 antibody-drug conjugate (ADC) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC). [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4310. doi:10.1158/1538-7445.AM2015-4310