Efficacy and safety of pembrolizumab in recurrent/metastatic head and neck squamous cell carcinoma: pooled analyses after long-term follow-up in KEYNOTE-012.

BACKGROUND: Second-line treatment options for advanced head and neck squamous cell carcinoma (HNSCC) are limited. The phase Ib KEYNOTE-012 study evaluated the safety and the efficacy of pembrolizumab for the treatment of HNSCC after long-term follow-up. METHODS: Multi-centre, non-randomised trial included two HNSCC cohorts (initial and expansion) in which 192 patients were eligible. Patients received pembrolizumab 10 mg/kg every 2 weeks (initial cohort; N = 60) or 200 mg every 3 weeks (expansion cohort; N = 132). Co-primary endpoints were safety and overall response rate (ORR; RECIST v1.1; central imaging vendor review). RESULTS: Median follow-up was 9 months (range, 0.2-32). Treatment-related adverse events (AEs) of any grade and grade 3/4 occurred in 123 (64%) and 24 (13%) patients, respectively. No deaths were attributed to treatment-related AEs. ORR was 18% (34/192; 95% CI, 13-24%). Median response duration was not reached (range, 2+ to 30+ months); 85% of responses lasted ≥6 months. Overall survival at 12 months was 38%. CONCLUSIONS: Some patients received 2 years of treatment and the responses were ongoing for more than 30 months; the durable anti-tumour activity and tolerable safety profile, observed with long-term follow-up, support the use of pembrolizumab as a treatment for recurrent/metastatic HNSCC.

CEA-CD3 bispecific antibody cibisatamab with or without atezolizumab in patients with CEA-positive solid tumours: results of two multi-institutional Phase 1 trials.

Cibisatamab is a bispecific antibody-based construct targeting carcinoembryonic antigen (CEA) on tumour cells and CD3 epsilon chain as a T-cell engager. Here we evaluated cibisatamab for advanced CEA-positive solid tumours in two open-label Phase 1 dose-escalation and -expansion studies: as a single agent with or without obinutuzumab in S1 (NCT02324257) and with atezolizumab in S2 (NCT02650713). Primary endpoints were safety, dose finding, and pharmacokinetics in S1; safety and dose finding in S2. Secondary endpoints were anti-tumour activity (including overall response rate, ORR) and pharmacodynamics in S1; anti-tumour activity, pharmacodynamics and pharmacokinetics in S2. S1 and S2 enrolled a total of 149 and 228 patients, respectively. Grade ≥3 cibisatamab-related adverse events occurred in 36% of S1 and 49% of S2 patients. The ORR was 4% in S1 and 7% in S2. In S2, patients with microsatellite stable colorectal carcinoma (MSS-CRC) given flat doses of cibisatamab and atezolizumab demonstrated an ORR of 14%. In S1 and S2, 40% and 52% of patients, respectively, developed persistent anti-drug antibodies (ADAs). ADA appearance could be mitigated by obinutuzumab-pretreatment, with 8% of patients having persistent ADAs. Overall, cibisatamab warrants further exploration in immunotherapy combination strategies for MSS-CRC.

NCI 7977: A Phase I Dose-Escalation Study of Intermittent Oral ABT-888 (Veliparib) plus Intravenous Irinotecan Administered in Patients with Advanced Solid Tumors.

Purpose: Veliparib is a PARP inhibitor (PARPi) with activity in BRCA 1/2/PALB2-deficient tumors. Preclinical observations reveal topoisomerase inhibitors like irinotecan are synergistic with PARPi irrespective of homologous recombination deficiency (HRD), potentially expanding the role for PARPi. Experimental Design: NCI 7977 was a multicohort phase I clinical trial evaluating the safety and efficacy of multiple dose schedules of veliparib with irinotecan for solid tumors. In the intermittent veliparib cohort, escalating doses of veliparib were given twice daily at dose level (DL) 1 (50 mg) and DL 2 (100 mg) days 1-4 and 8-11 with irinotecan 100 mg/m2 days 3 and 10 in 21-day cycles. Results: Fifteen patients enrolled, 8 of 15 (53%) received ≥4 prior systemic treatments. At DL1, 1 of 6 patients experienced a dose-limiting toxicity (DLT) of diarrhea. At DL2, 9 patients were treated, with 3 unevaluable for DLT, and 2 of 6 evaluable patients experienced a DLT of grade 3 neutropenia. Irinotecan 100 mg/m2 and veliparib 50 mg twice daily was the MTD. No objective responses were observed, although 4 patients had progression-free survival >6 months. Conclusions: The MTD of intermittent veliparib is 50 mg twice daily days 1-4 and 8-11 with weekly irinotecan 100 mg/m2 days 3 and 10 every 21 days. Multiple patients experienced prolonged stable disease irrespective of HRD and prior irinotecan. However, due to the toxicities with higher dose intermittent veliparib and irinotecan, this schedule was determined too toxic for further development and the arm was closed prematurely. Significance: The combination of intermittent veliparib with weekly irinotecan was deemed too toxic for further development. Future PARPi combinations should focus on agents with nonoverlapping toxicities to improve tolerability. The treatment combination showed limited efficacy with prolonged stable disease observed in multiple heavily pretreated patients, but no objective responses were seen.

BRCA2 BRC missense variants disrupt RAD51-dependent DNA repair.

Pathogenic mutations in the BRCA2 tumor suppressor gene predispose to breast, ovarian, pancreatic, prostate, and other cancers. BRCA2 maintains genome stability through homology-directed repair (HDR) of DNA double-strand breaks (DSBs) and replication fork protection. Nonsense or frameshift mutations leading to truncation of the BRCA2 protein are typically considered pathogenic; however, missense mutations resulting in single amino acid substitutions can be challenging to functionally interpret. The majority of missense mutations in BRCA2 have been classified as Variants of Uncertain Significance (VUS) with unknown functional consequences. In this study, we identified three BRCA2 VUS located within the BRC repeat region to determine their impact on canonical HDR and fork protection functions. We provide evidence that S1221P and T1980I, which map to conserved residues in the BRC2 and BRC7 repeats, compromise the cellular response to chemotherapeutics and ionizing radiation, and display deficits in fork protection. We further demonstrate biochemically that S1221P and T1980I disrupt RAD51 binding and diminish the ability of BRCA2 to stabilize RAD51-ssDNA complexes. The third variant, T1346I, located within the spacer region between BRC2 and BRC3 repeats, is fully functional. We conclude that T1346I is a benign allele, whereas S1221P and T1980I are hypomorphic disrupting the ability of BRCA2 to fully engage and stabilize RAD51 nucleoprotein filaments. Our results underscore the importance of correctly classifying BRCA2 VUS as pathogenic variants can impact both future cancer risk and guide therapy selection during cancer treatment.

Influence of tumor mutational burden, inflammatory gene expression profile, and PD-L1 expression on response to pembrolizumab in head and neck squamous cell carcinoma.

BACKGROUND: To characterize genomic determinants of response to pembrolizumab in recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) in the KEYNOTE-012 study. METHODS: Associations between biomarkers (tumor mutational burden (TMB), neoantigen load (NL), 18-gene T-cell-inflamed gene expression profile (TcellinfGEP), and PD-L1 combined positive score (CPS)) and clinical outcomes with pembrolizumab were assessed in patients with R/M HNSCC (n=192). Tumor human papillomavirus (HPV) status was also evaluated with the use of p16 immunohistochemistry and whole exome sequencing (WES; HPV+, mapping >20 HPV reads) in pretreatment tumor samples (n=106). RESULTS: TMB, clonality-weighted TMB, and TcellinfGEP were significantly associated with objective response (p=0.0276, p=0.0201, and p=0.006, respectively), and a positive trend was observed between NL and PD-L1 CPS and clinical response (p=0.0550 and p=0.0682, respectively). No correlation was observed between TMB and TcellinfGEP (Spearman ρ=-0.026) or TMB and PD-L1 (Spearman ρ=0.009); a correlation was observed between TcellinfGEP and PD-L1 (Spearman ρ=0.511). HPV status by WES and p16 immunohistochemistry showed concordance (84% Ò¡=0.573) among patients whose HPV results were available using both methods. CONCLUSIONS: TMB and inflammatory biomarkers (TcellinfGEP and PD-L1) may represent distinct and complementary biomarkers predicting response to anti-programmed death 1 therapies in HNSCC; further study of these relationships in randomized clinical trials is needed. TRIAL REGISTRATION NUMBER: NCT01848834.

Anti-CSF-1R emactuzumab in combination with anti-PD-L1 atezolizumab in advanced solid tumor patients naïve or experienced for immune checkpoint blockade.

BACKGROUND: This phase 1b study (NCT02323191) evaluated the safety, antitumor activity, pharmacokinetics, and pharmacodynamics of colony-stimulating factor-1 receptor-blocking monoclonal antibody (mAb) emactuzumab in combination with the programmed cell death-1 ligand (PD-L1)-blocking mAb atezolizumab in patients with advanced solid tumors naïve or experienced for immune checkpoint blockers (ICBs). METHODS: Emactuzumab (500-1350 mg flat) and atezolizumab (1200 mg flat) were administered intravenously every 3 weeks. Dose escalation of emactuzumab was conducted using the 3+3 design up to the maximum tolerated dose (MTD) or optimal biological dose (OBD). Extension cohorts to evaluate pharmacodynamics and clinical activity were conducted in metastatic ICB-naive urothelial bladder cancer (UBC) and ICB-pretreated melanoma (MEL), non-small cell lung cancer (NSCLC) and UBC patients. RESULTS: Overall, 221 patients were treated. No MTD was reached and the OBD was determined at 1000 mg of emactuzumab in combination with 1200 mg of atezolizumab. Grade ≥3 treatment-related adverse events occurred in 25 (11.3%) patients of which fatigue and rash were the most common (14 patients (6.3%) each). The confirmed objective response rate (ORR) was 9.8% for ICB-naïve UBC, 12.5% for ICB-experienced NSCLC, 8.3% for ICB-experienced UBC and 5.6% for ICB-experienced MEL patients, respectively. Tumor biopsy analyses demonstrated increased activated CD8 +tumor infiltrating T lymphocytes (TILs) associated with clinical benefit in ICB-naïve UBC patients and less tumor-associated macrophage (TAM) reduction in ICB-experienced compared with ICB-naïve patients. CONCLUSION: Emactuzumab in combination with atezolizumab demonstrated a manageable safety profile with increased fatigue and skin rash over usual atezolizumab monotherapy. A considerable ORR was particularly seen in ICB-experienced NSCLC patients. Increase ofCD8 +TILs under therapy appeared to be associated with persistence of a TAM subpopulation.

Clinical Efficacy of Olaparib in IDH1/IDH2-Mutant Mesenchymal Sarcomas.

PURPOSE: Tumors with neomorphic mutations in IDH1/2 have defective homologous recombination repair, resulting in sensitivity to poly (ADP-ribose) polymerase (PARP) inhibition. The Olaparib Combination trial is a phase II, open-label study in which patients with solid tumors harboring IDH1/2 mutations were treated with olaparib as monotherapy, with objective response and clinical benefit rates as the primary end points. METHODS: Ten patients with IDH1/2-mutant tumors by next-generation sequencing were treated with olaparib 300 mg twice daily. RESULTS: Three of five patients with chondrosarcomas had clinical benefit, including one patient with a partial response and two with stable disease lasting > 7 months. A patient with pulmonary epithelioid hemangioendothelioma had stable disease lasting 11 months. In contrast, clinical benefit was not observed among four patients with cholangiocarcinoma. CONCLUSION: These results indicate preliminary activity of PARP inhibition in patients with IDH1/2-mutant chondrosarcoma and pulmonary epithelioid hemangioendothelioma. Further studies of PARP inhibitors alone and in combination in this patient population are warranted.

A Phase I Study of an MPS1 Inhibitor (BAY 1217389) in Combination with Paclitaxel Using a Novel Randomized Continual Reassessment Method for Dose Escalation.

PURPOSE: Monopolar spindle 1 (MPS1) kinase inhibitor, BAY 1217389 (BAY) synergizes with paclitaxel. This phase I study assessed the combination of BAY with paclitaxel using a novel randomized continuous reassessment method (rCRM) to improve dose determination. PATIENTS AND METHODS: Patients with solid tumors were randomized to receive oral BAY (twice daily 2-days-on/5-days-off) with weekly paclitaxel (90 mg/m2) or paclitaxel monotherapy in cycle 1. Dose escalation was guided by CRM modeling. Primary objectives were to assess safety, establish the MTD of BAY, and to evaluate the pharmacokinetic profiles for both compounds. Simulations were performed to determine the contribution of the rCRM for dose determination. RESULTS: In total, 75 patients were enrolled. The main dose-limiting toxicities were hematologic toxicities (55.6%). The MTD of BAY was established at 64 mg twice daily with paclitaxel. Inclusion of a control arm enabled the definitive attribution of grade ≥3 neutropenia to higher BAY exposure [AUC0-12 (P< 0.001)]. After determining the MTD, we included 19 patients with breast cancer at this dose for dose expansion. Other common toxicities were nausea (45.3%), fatigue (41.3%), and diarrhea (40.0%). Overall confirmed responses were seen in 31.6% of evaluable patients. Simulations showed that rCRM outperforms traditional designs in determining the true MTD. CONCLUSIONS: The combination of BAY with paclitaxel was associated with considerable toxicity without a therapeutic window. However, the use of the rCRM design enabled us to determine the exposure-toxicity relation for BAY. Therefore, we propose that the rCRM could improve dose determination in phase I trials that combine agents with overlapping toxicities.

A phase I study with neratinib (HKI-272), an irreversible pan ErbB receptor tyrosine kinase inhibitor, in patients with solid tumors.

PURPOSE: The dose-limiting toxicities, maximum tolerated dose, pharmacokinetic profile, and preliminary antitumor activity of neratinib (HKI-272), an irreversible pan ErbB inhibitor, were determined in patients with advanced solid tumors. EXPERIMENTAL DESIGN: Neratinib was administered orally as a single dose, followed by a 1-week observation period, and then once daily continuously. Planned dose escalation was 40, 80, 120, 180, 240, 320, 400, and 500 mg. For pharmacokinetic analysis, timed blood samples were collected after administration of the single dose and after the first 14 days of continuous daily administration. RESULTS: Dose-limiting toxicity was grade 3 diarrhea, which occurred in one patient treated with 180 mg and in four patients treated with 400 mg neratinib; hence, the maximum tolerated dose was determined to be 320 mg. Other common neratinib-related toxicities included nausea, vomiting, fatigue, and anorexia. Exposure to neratinib was dose dependent, and the pharmacokinetic profile of neratinib supports a once-a-day dosing regimen. Partial response was observed for 8 (32%) of the 25 evaluable patients with breast cancer. Stable disease >or=24 weeks was observed in one evaluable breast cancer patient and 6 (43%) of the 14 evaluable non-small cell lung cancer patients. CONCLUSION: The maximum tolerated dose of once-daily oral neratinib is 320 mg. The most common neratinib-related toxicity was diarrhea. Antitumor activity was observed in patients with breast cancer who had previous treatment with trastuzumab, anthracyclines, and taxanes, and tumors with a baseline ErbB-2 immunohistochemical staining intensity of 2+ or 3+. The antitumor activity, tolerable toxicity profile, and pharmacokinetic properties of neratinib warrant its further evaluation.

Preclinical investigations and a first-in-human phase I trial of M4112, the first dual inhibitor of indoleamine 2,3-dioxygenase 1 and tryptophan 2,3-dioxygenase 2, in patients with advanced solid tumors.

BACKGROUND: M4112 is an oral, potent, and selective indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase 2 (TDO2) dual inhibitor. Here, we report preclinical data and first-in-human phase I data, including safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy, of M4112 monotherapy in patients with advanced solid tumors. METHODS: In preclinical studies, M4112 was administered to mice with IDO1-expressing tumors to determine tumor IDO1 and liver TDO2 inhibition. In the phase I trial, patients received doses of M4112 two times per day in 28-day cycles until progression, toxicity, or withdrawal of consent. The primary objective was to determine the maximum tolerated dose (MTD) and recommended phase II dose (RP2D). The primary endpoint was the incidence of dose-limiting toxicities (DLTs), treatment-emergent adverse events (TEAEs), and treatment-emergent changes in safety parameters. Other endpoints included pharmacokinetics, pharmacodynamics, and antitumor effects. RESULTS: In mice, M4112 significantly decreased the kynurenine:tryptophan ratio in the liver and tumor. Fifteen patients received M4112 at five distinct dose levels (three patients per cohort: 100, 200, 400, 600, and 800 mg two times per day orally). Initially, all doses inhibited IDO1 ex vivo, but plasma kynurenine levels returned to or exceeded baseline levels after day 15. Despite initial changes in kynurenine, there was no significant reduction of plasma kynurenine at steady state. There was one DLT (grade 3 allergic dermatitis; 800 mg two times per day) and one grade 2 QT prolongation (800 mg two times per day), resulting in dose reduction (not a DLT). M4112 was well tolerated, and neither the MTD nor the RP2D was established. TEAEs included fatigue, nausea, and vomiting. The best overall response was stable disease (n=9, 60%). CONCLUSIONS: There were no serious safety concerns at any dose. Although M4112 inhibited IDO1 activity ex vivo, plasma kynurenine levels were not reduced despite achieving target exposure.Trial registration number NCT03306420.

A Phase I Study of DLYE5953A, an Anti-LY6E Antibody Covalently Linked to Monomethyl Auristatin E, in Patients with Refractory Solid Tumors.

PURPOSE: DLYE5953A is an antibody-drug conjugate consisting of an anti-LY6E antibody covalently linked to the cytotoxic agent monomethyl auristatin E. This study characterized the safety, pharmacokinetics, immunogenicity, potential biomarkers, and antitumor activity of DLYE5953A in patients with metastatic solid tumors. PATIENTS AND METHODS: This was a phase I, open-label, 3+3 dose-escalation, and dose-expansion study of DLYE5953A administered intravenously every 21 days (Q3W) in patients with locally advanced or metastatic solid malignancies. RESULTS: Sixty-eight patients received DLYE5953A (median, four cycles; range, 1-27). No dose-limiting toxicities were identified during dose escalation (0.2-2.4 mg/kg; n = 20). The recommended phase II dose (RP2D) of 2.4 mg/kg Q3W was based on overall safety and tolerability. Dose-expansion cohorts for HER2-negative metastatic breast cancer (HER2-negative MBC; n = 23) and non-small cell lung cancer (NSCLC; n = 25) patients were enrolled at the RP2D. Among patients receiving DLYE5953A 2.4 mg/kg (n = 55), the most common (≥30%) related adverse events (AEs) included alopecia, fatigue, nausea, and peripheral neuropathy. Grade ≥3 related AEs occurred in 14 of 55 (26%) patients, with neutropenia being the most common (13%). DLYE5953A demonstrated linear total antibody pharmacokinetics at doses of ≥0.8 mg/kg with low unconjugated monomethyl auristatin E levels in blood. Partial response was confirmed in eight of 68 (12%) patients, including three of 29 patients with MBC (10%) and five of 25 patients with NSCLC (20%) at the RP2D. Stable disease was the best response for 37 of 68 (54%) patients. CONCLUSIONS: DLYE5953A administered at 2.4 mg/kg has acceptable safety. Preliminary evidence of antitumor activity in patients with HER2-negative MBC and NSCLC supports further investigation of LY6E as a therapeutic target.

First-in-Class, First-in-Human Study Evaluating LV305, a Dendritic-Cell Tropic Lentiviral Vector, in Sarcoma and Other Solid Tumors Expressing NY-ESO-1.

PURPOSE: LV305 is a modified, third-generation, nonreplicating, integration-deficient lentivirus-based vector designed to selectively transduce dendritic cells in vivo. LV305 induces expression of the New York Esophageal Squamous Cell Carcinoma-1 (NY-ESO-1) cancer testis antigen in dendritic cells, promoting immune responses against NY-ESO-1-expressing tumors. This phase I study evaluated the safety, immunogenicity, and preliminary efficacy of LV305 in patients with sarcoma or other solid tumors. PATIENTS AND METHODS: Adults with previously treated, advanced, NY-ESO-1-positive solid tumors and limited tumor burden were eligible. LV305 was administered every 3 weeks by intradermal injection in four dose cohorts (Cohort 1: 108 vector genomes (vg) x 3 doses; Cohorts 1A, 2, and 3: 108 vg, 109 vg, 1010 vg x 4 doses). RESULTS: Thirty-nine patients were enrolled: 3 patients each in Cohorts 1, 1A, and 2, and 30 patients in Cohort 3. No dose-limiting toxicities were observed. Tumor types included sarcoma (n = 24), ovarian (n = 8), melanoma (n = 6), and lung cancer (n = 1). All treatment-related adverse events were grade 1 or 2. Common treatment-related adverse events were fatigue (49%), injection site reactions (46%), and myalgia (21%). The disease control rate was 56.4% in all patients and 62.5% in sarcoma patients. One patient with synovial sarcoma achieved a partial response lasting >36 months. Anti-NY-ESO-1-specific CD4+ and/or CD8+ T cells were induced in 57% of evaluable sarcoma patients. Induction of an anti-NY-ESO-1 immune response was associated with improved 1-year survival in an exploratory analysis. CONCLUSIONS: This first-in-class, first-in-human study of LV305 demonstrated a favorable safety profile, induction of antigen-specific responses, and potential clinical activity in patients with advanced cancer.

Phase I clinical trial of STA-4783 in combination with paclitaxel in patients with refractory solid tumors.

PURPOSE: STA-4783 is a new compound that markedly enhances the therapeutic index of paclitaxel against human tumor xenograft models. A phase I clinical trial was undertaken to determine the maximum tolerated dose, toxicity profile, and pharmacokinetics of STA-4783 in combination with paclitaxel. EXPERIMENTAL DESIGN: Adults with refractory solid tumors concurrently received STA-4783 and paclitaxel as a 3-h i.v. infusion at starting doses of 44 and 135 mg/m(2), respectively. After increasing paclitaxel to 175 mg/m(2), the STA-4783 dose was escalated as permitted by dose-limiting toxicity during the first 21-day cycle. RESULTS: Thirty-five patients were treated with eight dose levels of STA-4783/paclitaxel. In patients receiving 175 mg/m(2) paclitaxel, the incidence of severe toxicity increased with escalation of the STA-4783 dose above 263 mg/m(2), and 438 mg/m(2) was the maximum tolerated dose. All toxicities were typical of paclitaxel, with neutropenia, mucositis, and myalgia/arthralgia being dose limiting. Partial responses were achieved in one patient with Kaposi's sarcoma and another with ovarian cancer that progressed during prior treatment with paclitaxel. STA-4783 exhibited linear pharmacokinetics characterized by rapid elimination from plasma (biological half-life, 1.06 +/- 0.24 h) and a low steady-state apparent volume of distribution (25.1 +/- 8.1 L/m(2)). The total body clearance of paclitaxel decreased significantly with escalation of the STA-4783 dose. CONCLUSIONS: The STA-4783/paclitaxel combination was well tolerated with a toxicity profile similar to single-agent paclitaxel. Enhanced systemic exposure to paclitaxel resulting from a dose-dependent interaction with STA-4783 was associated with increased toxicity. Objective responses in two heavily pretreated patients, both with taxane exposure, have encouraged further clinical evaluation of this regimen.

Phase I study of gefitinib, irinotecan, 5-fluorouracil and leucovorin in patients with metastatic colorectal cancer.

PURPOSE: To determine the maximum tolerated doses (MTD), toxicities, efficacy, and pharmacokinetics (PK) of gefitinib combined with irinotecan, 5-fluorouracil (5-FU) and leucovorin (IFL) in patients with previously untreated advanced colorectal cancer. EXPERIMENTAL DESIGN: Starting doses were gefitinib 250 mg/day orally without interruption, irinotecan 100 mg/m(2) as a 90 min intravenous (i.v.) infusion, 5-FU 400 mg/m(2) bolus i.v. and leucovorin 20 mg/m(2) i.v. on days 1 and 8 of a 21-day cycle. Dose escalations involved increasing gefitinib to 500 mg then increasing irinotecan to 125 mg/m(2) and 5-FU to 500 mg/m(2). RESULTS: Twenty-four patients received therapy. The starting doses proved to be the MTD, as attempts to increase the dose of either gefitinib or the chemotherapeutic agents resulted in dose-limiting toxicities. Gastrointestinal effects and bone marrow suppression were the principal toxicities; however, only 1/17 (6%) patients treated with the MTD had severe (grades 3-4) diarrhea and severe neutropenia occurred in only two (12%) patients. Partial responses occurred in 10/17 patients receiving the MTD and another five had stable disease. Median progression-free and overall survivals were 12.2 and 26.6 months, respectively. In ten patients treated with the MTD, the steady-state PK of gefitinib was not affected by IFL nor did gefitinib appear to influence the PK of either irinotecan or 5-FU. CONCLUSIONS: Gefitinib can be safely combined with an intermittent weekly schedule of IFL. Evidence of promising activity should encourage further clinical evaluation of epidermal growth factor receptor tyrosine kinase inhibitors, such as gefitinib, combined with multiagent chemotherapy for metastatic colorectal cancer.