Investigational Nanoparticle-drug Conjugate Research Articles

A phase Ib/II and pharmacokinetic study of EP0057 (formerly CRLX101) in combination with weekly paclitaxel in patients with recurrent or persistent epithelial ovarian, fallopian tube, or primary peritoneal cancer

Background: EP0057 (formerly CRLX101) is an investigational nanoparticle-drug conjugate (NDC) of a cyclodextrin-based polymer backbone plus camptothecin, a topoisomerase-1 inhibitor. Prior studies showed efficacy in recurrent or persistent, epithelial ovarian, fallopian tube or primary peritoneal cancer (EOC).Methods: This phase Ib/2 trial assessed safety and efficacy of EP0057 Q2W plus weekly paclitaxel in patients with EOC. The recommended phase 2 dose (RP2D) was identified using a 3+3 design. The single-arm phase 2 assessed overall response (ORR) per RECIST 1.1 in patients previously treated with bevacizumab. Secondary objectives included progression free survival (PFS) and duration of response.Results: The RP2D was established as 15 mg/m2 EP0057 Q2W plus 80 mg/m2 paclitaxel administered 3 weeks on/1 week off. Nine patients enrolled on phase 1b, with no DLTs; 21 additional patients enrolled on phase 2. All completed >1 cycle. Median age was 62 (44-76) years, 57% ≥3 prior therapies. For the primary analysis, 6/19 patients with prior bevacizumab had confirmed responses (ORR=31.6% (95% CI: 15.4% to 54.0%)) including one complete response (CR). Median PFS was 5.4 months. Most common grade 3/4 adverse events attributed to treatment were decreased neutrophil count (13, 43%) and anemia (3, 10%).Conclusions: Although the observed ORR was not statistically better than the historical control rate, EP0057 remains an interesting option for treatment of recurrent EOC. EP0057 exhibits high plasma drug retention, slow clearance, and controlled slow release of CPT from the polymer when administered alone and with paclitaxel. (NCT02389985) 242 words

Abstract CT151: A Phase II study of NLG207 (formerly CRLX101) in combination with weekly paclitaxel in patients with recurrent or persistent epithelial ovarian, fallopian tube or primary peritoneal cancer

Abstract Background: NLG207 (formerly CRLX101) is an investigational nanoparticle-drug conjugate (NDC) composed of a cyclodextrin-based polymer backbone linked to camptothecin, a topoisomerase-1 inhibitor. NDCs enhance drug delivery to tumors where gradual payload release inside cancer cells augments antitumor activity while reducing toxicity. The RP2D of CRLX101 was previously set at 15 mg/m2 Q2W in combination with 80 mg/m2 weekly paclitaxel in Phase I and reported at ESMO 2016. This abstract will include data from both the Phase Ib and the phase II expansion. Methods: In this Phase II single arm study, patients were treated with NLG207 (Q2W) and 80 mg/m2 paclitaxel (3 wks on/1 wk off) repeated q 28 days until progression or toxicity. Primary objective was overall response (CR + PR) via RECIST v1.1 in women with recurrent platinum resistant epithelial ovarian, fallopian tube or primary peritoneal cancer. Progression free survival (PFS), duration of response (DOR), and safety were also assessed. Results: Thirty patients were enrolled and all completed at least one cycle. Median age was 62 (44-76) years. 57% of patients received ≥3 prior therapies. There were 8/30 confirmed responses for an overall response rate (ORR) of 26.7% (95% CI 14.2%, 44.4%), including one complete response (CR). ORR for platinum resistant patients (n=17) was 23.5% (4/17) vs. 30.8% (4/13) for those who were platinum sensitive (n=13) to their most recent platinum regimen. Best response (including unconfirmed) for platinum resistant patients was 41.2% (7/17) including 7 PRs. Five additional platinum resistant patients achieved stable disease (SD). Median PFS (mPFS) for all study patients was 5.4 months. The mPFS was similar for both platinum resistant at 5.5 months and platinum sensitive at 5.4 months. Median DOR was 7.2 months for platinum resistant patients vs. 4.7 months for the platinum sensitive group. The most common grade 3/4 adverse events (AEs) attributed to study treatment were: decreased neutrophil count (13 patients, 43%), anemia (3 patients, 10%), hematuria (2 patients, 7%); urinary tract infection (UTI), cystitis, hypertension, and hypokalemia (all seen in 1 patient, 3%). PK data will be included in the full presentation. Conclusions: NLG207 is a potentially best-in-class topoisomerase 1 inhibitor with demonstrated antitumor activity in recurrent ovarian cancer including those who have become resistant to platinum therapy. AE profile of this combination is consistent with that seen for paclitaxel as a single agent except for cystitis, hematuria and UTI. It was well-tolerated in combination with weekly paclitaxel in heavily pre-treated patients. NLG207 warrants further investigation in combination therapy regimens for recurrent ovarian, fallopian tube or primary peritoneal cancer, particularly in platinum resistant patients. Citation Format: Linda Duska, David M. O'Malley, Carolyn Krasner, Russell J. Schilder, Cara Mathews, Kathleen Moore, Premal Thaker, Austin Miller, Christopher Purdy, A.J. Leyco, Christopher Smith, Deborah Mercier, Lucinda Tennant, Eugene Kennedy, Nicholas Vahanian, Charles Link. A Phase II study of NLG207 (formerly CRLX101) in combination with weekly paclitaxel in patients with recurrent or persistent epithelial ovarian, fallopian tube or primary peritoneal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT151.

Pilot trial of CRLX101 in patients with advanced, chemotherapy-refractory gastroesophageal cancer.

CRLX101 is an investigational nanoparticle-drug conjugate with a camptothecin payload. Preclinical evidence indicated preferential uptake in tumors, and tumor xenograft models demonstrate superiority of CRLX101 over irinotecan. A pilot trial was conducted at recommended phase 2 dosing (RP2D) using the bimonthly schedule to assess preferential uptake of CRLX101 in tumor vs. adjacent normal tissue in endoscopically accessible tumors in chemotherapy-refractory gastroesophageal cancer. Results from the biopsies were previously reported and herein we present the clinical outcomes. Patients initiated CRLX101 dosed at RP2D (15 mg/m2) on days 1 and 15 of a 28-day cycle. Detection of preferential CRLX101 tumor uptake was the primary endpoint and objective response rate (ORR) was a secondary endpoint. With a sample size of ten patients, the study had 90% power to detect ≥1 responder if the true response rate is ≥21%. Between Dec. 2012 and Dec. 2014, ten patients with chemotherapy-refractory (median 2 prior lines of therapy, range 1-4) gastric adenocarcinoma were enrolled. The median time-to-progression was 1.7 months. Best response was seen in one patient with stable disease (SD) for 8 cycles. Only ≥ grade 3 drug-related toxicity occurred in one patient with grade 3 cardiac chest pain who was able to resume therapy after CRLX101 was reduced to 12 mg/m2. Bimonthly CRLX101 demonstrated minimal activity with SD as best response in this heavily pretreated population. Future efforts with CRLX101 in gastric cancer should focus on combination and more dose-intensive strategies given its favorable toxicity profile and evidence of preferential tumor uptake.

Phase Ib/II study of neoadjuvant chemoradiotherapy with CRLX101 and capecitabine for locally advanced rectal cancer.

e15144 Background: There is strong interest in the development of novel agents to further improve the therapeutic ratio of neoadjuvant chemoradiotherapy for rectal cancer. CRLX101 is an investigational nanoparticle-drug conjugate with a camptothecin payload. The purpose of this Phase Ib/II study is to assess toxicity and to evaluate whether the addition of CRLX101 to chemoradiotherapy can improve pathologic complete response (pCR) for rectal cancer. Methods: This is a single-arm multicenter Phase Ib/II study examining the addition of CRLX101 to a standard capecitabine-based chemoradiotherapy regimen. Phase Ib employs a 3+3 dose escalation design with starting dose of 12 mg/m2 every other week (QOW). Dose level +1 was 15 mg/m2 (MTD for CRLX101 single agent QOW). Upon reaching MTD for QOW dosing, protocol was modified to evaluate QW CRLX101 dosing starting at 12 mg/m2 and 15 mg/m2as +1 level. Secondary endpoints included pCR and clinical outcome. Results: A total of 32 patients were enrolled on the trial. 26/32 had T3-4, 9/32 had N2 and 16/32 had N1 disease. For QOW dosing, 9 patients completed treatment without DLT and MTD was identified as 15 mg/m2 QOW. 14 patients were treated on the Phase II portion of the study at 15 mg/m2 QOW prior to the initiation of weekly dosing Phase Ib cohorts. For QW dosing, 0/3 patients experienced DLT at 12 mg/m2 and 1/6 patients experienced DLT at 15 mg/m2. The DLT was skin desquamation requiring treatment delay. QW MTD was identified as 15 mg/m2. Toxicities (all grade 3 except lymphopenia) that could possibly be attributed to CRLX101 are in Table 1. Full clinical and pathologic staging were available for 29/32 patients. Mean neoadjuvant rectal (NAR) score was 19 with standard deviation of 15. At the weekly MTD, 3/6 patients had pCR. Conclusions: CRLX101 weekly at 15 mg/m2+ standard capecitabine-based chemoradiotherapy appears to be well tolerated, with promising pCR rates that warrants further evaluation. A larger PhII trial should be considered with this regimen. Clinical trial information: NCT02010567. [Table: see text]

Abstract B32: CRLX101, an investigational camptothecin-containing nanoparticle-drug conjugate, combined with DDR agents provides a novel approach to increasing therapeutic index

Abstract Topoisomerase I inhibitors are used as standard-of-care chemotherapy in many types of cancer but are associated with significant toxicities. There is potential to improve their efficacy further by combining with inhibitors of the DNA damage response, such as the poly ADP ribose polymerase (PARP) inhibitor olaparib. However, while preclinical data highlight the improved efficacy of this combination, subsequent clinical trials have struggled due to dose limiting myelotoxicity. CRLX101 is an investigational nanoparticle-drug conjugate (NDC) containing the payload camptothecin, a potent topoisomerase I inhibitor. This agent is preferentially targeted to tumours and demonstrated a generally favorable toxicity profile in the clinic. Here, we explored the molecular mechanism and therapeutic potential of combining CRLX101 with either olaparib or the WEE1 G2 checkpoint kinase inhibitor AZD1775, by testing both efficacy and safety in preclinical models. In vitro studies using NCI-H417a small cell lung cancer (SCLC) cells demonstrated that combination with both olaparib and AZD1775 potentiated the efficacy of CRLX101 although by different mechanisms. Cellular analyses revealed that CRLX101 treatment alone predominantly activated ATM-mediated DNA damage response and resulted in late S/G2 cell cycle arrest. Combination with a PARP inhibitor further enhanced the CRLX101-induced DNA damage response and prolonged cell cycle arrest in late S/G2 phase. In contrast, WEE1 inhibition abrogated late S/G2 cell cycle arrest induced by CRLX101, resulting in aberrant mitotic entry and enhanced cell death. Our in vivo studies using wild type Wistar rat model showed that CRLX101, olaparib and AZD1775, are well tolerated as single agents. However, concurrent combination of CRLX101 with either olaparib or AZD1775 resulted in a dose-dependent decrease in hematological parameters. We investigated sequenced schedules and demonstrated that at a 24h delay between the CRLX101 and olaparib mitigates much of the combined bone marrow toxicity, while improving the efficacy above CRLX101 alone in xenograft tumors from NCI-H417a cells. Collectively, these preclinical data demonstrate increased anti-tumor efficacy of CRLX101 when combined with DDR inhibitors. The combination schedule for CRLX101 and olaparib identified in our preclinical models as providing an increased therapeutic index has been used to develop protocols to test this combination in a relapsed (2nd line) SCLC human clinical trial (in collaboration with NCI). Citation Format: Lenka Oplustil O'Connor, Anderson T. Wang, David Jones, Rajesh Odedra, Michael Spreadborough, Joanne Wilson, Aaron Smith, Peter Cotton, Jaimini Reens, Jen Barnes, Victoria Sheridan, Andres Tellez, Alan Lau, Claire Sadler, Mark J. O'Connor, Scott Eliasof. CRLX101, an investigational camptothecin-containing nanoparticle-drug conjugate, combined with DDR agents provides a novel approach to increasing therapeutic index [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr B32.

CRLX101, a Nanoparticle–Drug Conjugate Containing Camptothecin, Improves Rectal Cancer Chemoradiotherapy by Inhibiting DNA Repair and HIF1α

Novel agents are needed to improve chemoradiotherapy for locally advanced rectal cancer. In this study, we assessed the ability of CRLX101, an investigational nanoparticle-drug conjugate containing the payload camptothecin (CPT), to improve therapeutic responses as compared with standard chemotherapy. CRLX101 was evaluated as a radiosensitizer in colorectal cancer cell lines and murine xenograft models. CRLX101 was as potent as CPT in vitro in its ability to radiosensitize cancer cells. Evaluations in vivo demonstrated that the addition of CRLX101 to standard chemoradiotherapy significantly increased therapeutic efficacy by inhibiting DNA repair and HIF1α pathway activation in tumor cells. Notably, CRLX101 was more effective than oxaliplatin at enhancing the efficacy of chemoradiotherapy, with CRLX101 and 5-fluorouracil producing the highest therapeutic efficacy. Gastrointestinal toxicity was also significantly lower for CRLX101 compared with CPT when combined with radiotherapy. Our results offer a preclinical proof of concept for CRLX101 as a modality to improve the outcome of neoadjuvant chemoradiotherapy for rectal cancer treatment, in support of ongoing clinical evaluation of this agent (LCC1315 NCT02010567). Cancer Res; 77(1); 112-22. ©2016 AACR.

Preclinical Efficacy of Bevacizumab with CRLX101, an Investigational Nanoparticle-Drug Conjugate, in Treatment of Metastatic Triple-Negative Breast Cancer.

VEGF pathway-targeting antiangiogenic drugs, such as bevacizumab, when combined with chemotherapy have changed clinical practice for the treatment of a broad spectrum of human cancers. However, adaptive resistance often develops, and one major mechanism is elevated tumor hypoxia and upregulated hypoxia-inducible factor-1α (HIF1α) caused by antiangiogenic treatment. Reduced tumor vessel numbers and function following antiangiogenic therapy may also affect intratumoral delivery of concurrently administered chemotherapy. Nonetheless, combining chemotherapy and bevacizumab can lead to improved response rates, progression-free survival, and sometimes, overall survival, the extent of which can partly depend on the chemotherapy backbone. A rational, complementing chemotherapy partner for combination with bevacizumab would not only reduce HIF1α to overcome hypoxia-induced resistance, but also improve tumor perfusion to maintain intratumoral drug delivery. Here, we evaluated bevacizumab and CRLX101, an investigational nanoparticle-drug conjugate containing camptothecin, in preclinical mouse models of orthotopic primary triple-negative breast tumor xenografts, including a patient-derived xenograft. We also evaluated long-term efficacy of CRLX101 and bevacizumab to treat postsurgical, advanced metastatic breast cancer in mice. CRLX101 alone and combined with bevacizumab was highly efficacious, leading to complete tumor regressions, reduced metastasis, and greatly extended survival of mice with metastatic disease. Moreover, CRLX101 led to improved tumor perfusion and reduced hypoxia, as measured by contrast-enhanced ultrasound and photoacoustic imaging. CRLX101 durably suppressed HIF1α, thus potentially counteracting undesirable effects of elevated tumor hypoxia caused by bevacizumab. Our preclinical results show pairing a potent cytotoxic nanoparticle chemotherapeutic that complements and improves concurrent antiangiogenic therapy may be a promising treatment strategy for metastatic breast cancer. Cancer Res; 76(15); 4493-503. ©2016 AACR.

Abstract CT090: Phase II trial of the NDC CRLX101 in combination with bevacizumab in patients with platinum-resistant ovarian cancer (PROC)

Abstract Background: CRLX101 is an investigational nanoparticle-drug conjugate (NDC) with a camptothecin payload. CRLX101 is a dual inhibitor of topoisomerase 1 and hypoxia inducible factors 1α and 2α (HIF1-α and HIF-2α). CRLX101 is being explored clinically in several tumor types including renal cell carcinoma (RCC) in combination with Avastin®, (Keefe, ASCO 2015, 4543) and platinum-resistant ovarian cancer (PROC) (Krasner ASCO 2014, 5581). The PROC study has a CRLX101 monotherapy arm (Group A) and a combination arm with Avastin (Group B). Group A patients (pts) received CRLX101 at 15mg/m2 every other week and Group B patients received CRLX101 15 mg/m2 with Avastin 10 mg/kg every other week until progression or unacceptable toxicity. The primary endpoint for both groups was rate of progression free survival at 6 months (PFS6) using RECIST 1.1 criteria. Secondary endpoints were objective response rate (ORR), PFS, ?50% reduction of CA125 over baseline, and safety. Adverse events (AEs) were assessed by CTCAE v4.0. Pre- and post-treatment tumor biopsies were collected from a cohort of patients in Group A to evaluate relevant PD endpoints, suggesting that CRLX101 is active in PROC. Results: A total of 18 PROC patients were evaluated in Group B. Demographics: Median age of the patient was 59years (range: 46-68). Median number of previous regimens was 2 (range: 1-3), ECOG PS 0 (13 pts) or 1 (5 pts). The PFS6 was demonstrated in 56% pts (10 out of 18). The PR and stable disease (SD) rates were 17% (3 out of 18 pts) and 78% (14 out of 18 pts), respectively. Median progression-free survival is 6.2 months to date. A ? 50% decline in CA125 was demonstrated in 44% pts (8 out of 18). AEs most commonly observed with the combination were nausea (10 pts, 56%), anemia (10 pts, 56%); proteinuria (8 pts, 44%) and fatigue (6 pts, 33%). The majority of AEs were Grade 1. There were only two drug-related AEs Grade ? 3: one patient developed uncomplicated and reversible elevated ALT (grade 3) and another patient had a short-lived decrease in ANC (grade 4). A retrospective analysis for both cohorts, Group A vs. Group B, demonstrated that the combination showed increased antitumor activity: PFS6: 27 vs 56%, mPFS 4.2 vs 6.2 months and CA125: 23 vs 44%. Conclusions: CRLX101 15 mg/m2 in combination with Avastin 10 mg/kg given every other week demonstrated antitumor activity and was generally well-tolerated in advanced PROC pts. An additional 25 pts will be enrolled in Group B. This combination is currently being explored in an ongoing randomized controlled Phase 2 trial in 3rd and 4th line RCC, and is also being tested in combination with weekly paclitaxel in an ongoing Phase 1b trial in PROC. Clinical trial information: NCT01652079 Citation Format: Carolyn Krasner, Michael Birrer, Christian Peters, Lata Jayaraman, Scott Eliasof, Andres Tellez, William Downing, Adrian Senderowicz. Phase II trial of the NDC CRLX101 in combination with bevacizumab in patients with platinum-resistant ovarian cancer (PROC). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr CT090.

Abstract 3721: A camptothecin-containing nanoparticle-drug conjugate combination with DDR agents provides a novel approach to increasing therapeutic index

Abstract Topoisomerase I inhibitors are used as standard-of-care chemotherapy in many types of cancer but are associated with significant toxicities. There is potential to improve their efficacy further by combining with inhibitors of the DNA damage response, such as the PARP inhibitor olaparib. However, while preclinical data highlight the improved efficacy of this combination, subsequent clinical trials have struggled due to dose limiting myelotoxicity. CRLX101 is an investigational nanoparticle-drug conjugate (NDC) containing the payload camptothecin (the most potent topoisomerase I inhibitor known). This agent is preferentially targeted to tumours and demonstrated a favourable toxicity profile in the clinic. Here, we explored the molecular mechanism and therapeutic potential of combining CRLX101 with either olaparib or the WEE1 inhibitor AZD1775, by testing both efficacy and safety in preclinical models. In vitro studies using NCI-H417a SCLC cells demonstrated that combination with both olaparib and AZD1775 potentiated the efficacy of CRLX101 although by different mechanisms. Cellular analyses revealed that CRLX101 treatment alone predominantly activated ATM-mediated DNA damage response and resulted in late S/G2 cell cycle arrest. Combination with a PARP inhibitor further enhanced the CRLX101-induced DNA damage response and prolonged cell cycle arrest in late S/G2 phase. In contrast, WEE1 inhibition abrogated late S/G2 cell cycle arrest induced by CRLX101, resulting in aberrant mitotic entry and enhanced cell death. Our in vivo studies using wild type Wistar rat model showed that CRLX101, olaparib and AZD1775, are well tolerated as single agents. However, concurrent combination of CRLX101 with either olaparib or AZD1775 resulted in a dose-dependent decrease in haematological parameters. We investigated sequenced schedules and demonstrated that at a 24h delay between the CRLX101 and olaparib mitigates much of the combined bone marrow toxicity, while improving the efficacy above CRLX101 alone in xenograft tumours from NCI-H417a cells. Collectively, these preclinical data demonstrate increased anti-tumour efficacy of CRLX101 when combined with DDR inhibitors. The combination schedule for CRLX101 and olaparib identified in our preclinical models as providing an increased therapeutic index has been used to develop protocols to test this combination in a relapsed (2nd line) SCLC human clinical trial (in collaboration with NCI). Citation Format: Lenka Oplustil O’Connor, Anderson T. Wang, David R. Jones, Rajesh Odedra, Michael Spreadborough, Joanne Wilson, Aaron Smith, Peter Cotton, Jaimini Reens, Jen Barnes, Victoria Sheridan, Scott Eliasof, Andres Tellez, Alan Lau, Claire Sadler, Mark J. O’Connor. A camptothecin-containing nanoparticle-drug conjugate combination with DDR agents provides a novel approach to increasing therapeutic index. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3721.

Abstract 3209: CRLX101, an investigational nanoparticle-drug conjugate of camptothecin, demonstrates synergy with immunotherapy agents in preclinical models

Abstract CRLX101, an investigational nanoparticle-drug conjugate (NDC) containing the payload camptothecin, is currently being clinically evaluated in multiple treatment-refractory solid tumors. CRLX101 has been shown preclinically to be active in many different tumor types as a dual inhibitor of topoisomerase 1 and hypoxia-inducible factor 1α (HIF-1α). It has a long circulation half-life and has been shown pre-clinically to release camptothecin in a slow and prolonged manner in tumors. Camptothecin itself was identified as an active anti-tumor agent preclinically but was not developed clinically due to its poor tolerability in patients. The development of CRLX101, which has not shown significant toxicity in over 300 patients to date, offers a unique opportunity to improve cancer treatment in a meaningful way. Recent publications have suggested that tumor expression of the immune-suppressive molecule PD-L1 is controlled by HIF-1α. Since CRLX101 is a potent inhibitor of HIF-1α, it is possible that CRLX101 behaves as an inhibitor of the PD-1/PD-L1 axis in vivo. We therefore hypothesized that a combination of CRLX101 with agents that are being investigated in combination with the anti PD-1 antibody would lead to increased efficacy. Indole diamine oxygenase (IDO) inhibitors are a new class of drugs that decrease tumor-induced immune suppression and are currently being evaluated in the clinic with anti-PD-1 antibodies. Using syngeneic tumor models, we tested the combination of CRLX101 with three different IDO inhibitors. Treatment of the B16.F10 melanoma model with IDO inhibitors NLG919, INCB024360 or indoximod had no effect on tumor growth while CRLX101 as monotherapy showed moderate anti-tumor activity. When CRLX101 was combined with any of the three IDO inhibitors, the anti-tumor activity was greatly improved compared to monotherapy. Similar results were noted in other syngeneic tumor models. This improved combination response was not observed in IDO inhibitor combinations with the clinically approved topoisomerase inhibitor irinotecan, suggesting that CRLX101 provides a unique advantage in this context. Interestingly, CRLX101/IDO inhibitor combination was also superior to the combination of anti-PD-1 antibody and IDO inhibitor. These data suggest that CRLX101 in combination with IDO inhibitors can successfully block host-mediated immune-suppression to enhance anti-tumor immunity, and this combination may therefore show improved therapeutic activity in the clinic. We therefore plan to explore the immune-specific effects of CRLX101 as well as the mechanistic basis for the observed combination response, and use that information to guide CRLX101 clinical strategy in the setting of chemo-immunotherapy regimens. Citation Format: Douglas Lazarus, Christian Peters, Adam Stockmann, Scott Eliasof, Lata Jayaraman. CRLX101, an investigational nanoparticle-drug conjugate of camptothecin, demonstrates synergy with immunotherapy agents in preclinical models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3209.

Abstract 1345: Tumor selective localization of CRLX101, an investigational nanoparticle-drug conjugate of camptothecin

Abstract CRLX101, an investigational nanoparticle-drug conjugate (NDC) containing the payload camptothecin, is currently being clinically evaluated in multiple treatment-refractory solid tumors. In preclinical models, CRLX101 is believed to release camptothecin in the tumor in a slow and prolonged manner due to its long circulation half-life. CRLX101 has been shown preclinically to be a dual inhibitor of topoisomerase 1 and hypoxia-inducible factor 1α. It has demonstrated striking anti-tumor activity in several different tumor models. Camptothecin itself was identified as an active anti-tumor agent preclinically but was not developed clinically due to its poor tolerability in patients. The development of CRLX101, which has not shown significant toxicity in over 300 patients to date, offers a unique opportunity to improve cancer treatment in a meaningful way. We hypothesized that CRLX101 utilizes the enhanced permeability and retention (EPR) effect to accumulate selectively in tumors. In this study, we sought to mechanistically dissect the process of CRLX101 entry and accumulation into tumor cells using multiple methods, both in vitro and in xenograft tumors in vivo. Using confocal microscopy, we detected camptothecin fluorescence in CRLX101-treated tumor cells in culture as well as in tumor tissue from mice treated with CRLX101. We can co-localize this camptothecin with intact nanoparticles using an anti-PEG antibody that specifically detects the PEG loops in the NDCs. More recently, we have shown that camptothecin and anti-PEG co-localize specifically in tumors of patients treated with CRLX101 but not in adjoining normal tissue. We can also demonstrate that macropinocytosis and activation of actin polymerization play a role in the process by which tumor cells take up CRLX101. Using an anti-CD31 antibody, we can visualize the distance traversed by CRLX101 from the tumor vasculature over time. We have developed novel analytical methods to precisely quantify both released and CRLX101-conjugated camptothecin over time in CRLX101 treated tumor cells in vitro, as well as in tumor tissue from mice treated with CRLX101 in vivo. Using cell viability assays, we can correlate the kinetics of camptothecin released inside tumor cells to the degree of tumor cell kill. We believe that these data are an important step forward in understanding the precise mechanism(s) underlying selective delivery of CRLX101 into tumor tissue. Citation Format: Christian G. Peters, Douglas Lazarus, Donna Brown, Ningning Zhang, Adam P. Stockmann, Roy Case, Ellen Rohde, Scott Eliasof, Lata Jayaraman. Tumor selective localization of CRLX101, an investigational nanoparticle-drug conjugate of camptothecin. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1345.

Preclinical effects of CRLX101, an investigational camptothecin-containing nanoparticle drug conjugate, on treating glioblastoma multiforme via apoptosis and antiangiogenesis.

Malignant gliomas are difficult to treat in clinical practice. This study was aimed to investigate the preclinical efficacy of CRLX101, an investigational nanoparticle-drug conjugate developed by conjugating camptothecin (CPT) with cyclodextrin-polyethylene glycol, against gliomas. CPT fluorescence was detected across tight-junction barriers and in mouse plasma and brain. Following CRLX101 treatment, CPT was distributed in the cytoplasm of human U87 MG glioma cells. U87 MG cell viability was decreased by CRLX101 and CPT. Moreover, CRLX101 induced less cytotoxicity to human astrocytes compared to CPT. Exposure of U87 MG cells to CRLX101 induced G2/M cell cycle arrest and apoptosis. Administration of CRLX101 induced apoptosis in mice brain tumor tissues and prolonged the survival rate of mice. In addition, CRLX101 inhibited hypoxia and angiogenesis by suppressing the expression of carbonic anhydrase IX, vascular endothelial growth factor, and CD31 in tumor sections. Taken together, this preclinical study showed that CRLX101 possesses antitumor abilities by inducing cell cycle arrest and apoptosis in glioma cells and inhibiting tumor angiogenesis, thereby prolonging the lifespan of mice bearing intracranial gliomas. These data support further research of CRLX101 in patients with brain tumors.

Pilot trial of CRLX101 in patients (pts) with advanced, chemotherapy-refractory gastroesophageal cancer (GEC).

44 Background: Camptothecin (CPT) derivatives such as irinotecan have activity in 2nd-line therapy in advanced GEC with reported response rates of 0-15%. CRLX101 is an investigational nanoparticle-drug conjugate (NDC) with a CPT payload. Preclinical evidence indicates preferential uptake in tumors, and animal GEC xenograft models demonstrate superiority of CRLX101 over irinotecan. A pilot trial was conducted at recommended phase 2 dosing (RP2D) to assess preferential uptake of CRLX101 in tumor vs. adjacent normal tissue in endoscopically accessible tumors in patients with chemotherapy-refractory GEC. Data demonstrating preferential tumor uptake of CRLX101 has been presented separately and here we report on the clinical outcomes of patients enrolled. Methods: All pts initiated CRLX101 dosed intravenously at RP2D (15 mg/m2) on days 1 and 15 of a 28-day cycle until disease progression or intolerant toxicity. While detection of preferential CRLX101 tumor uptake was the primary endpoint, with 10 pts enrolled a secondary analysis could be performed with the study having 90% power to detect ≥ 1 responder if the true response rate is ≥ 21%. Responses were assessed using RECIST 1.1. Results: Between Dec. 2012 and Dec. 2014, 10 patients with chemotherapy-refractory (median 2 prior lines of therapy, range 1-4) GEC and adenocarcinoma histology were enrolled and evaluable for response and toxicity. The median time-to-progression was 1.9 mo (range 0.6-8.7 mo). Best response was seen in 1 pt with stable disease (SD) for 8 cycles. Only ≥ grade 3 toxicities related to CRLX101 occurred in a single patient with grade 3 anemia and chest pain who was able to resume therapy without any further toxicity after CRLX101 was reduced to 12 mg/m2. Conclusions: CRLX101 demonstrated minimal activity with SD as best response in this heavily pretreated population. Future efforts with CRLX101 in advanced GEC should focus on combination strategies. Its favorable toxicity profile and evidence of preferential tumor uptake support further clinical research of combining CRLX101 with other targeted therapies such as anti-angiogenesis (ramucirumab) and/or immune checkpoint inhibitors. Clinical trial information: NCT01612546 Clinical trial information: NCT01612546.

Abstract B33: CRLX101, an investigational nanoparticle-drug conjugate, localizes in human tumors and not in adjacent healthy tissue after intravenous dosing

Abstract Background: Nanoparticle-based therapeutics are thought to rely on the enhanced permeability and retention effect to preferentially localize in solid tumors and not healthy tissue. These phenomena are rationalized primarily from animal models of the human disease. There is a need to obtain analogous information from humans in order to better understand how nanoparticle-based therapeutics perform in humans. CRLX101 is an investigational nanoparticle drug conjugate (NDC) consisting of a cyclodextrin-containing polymer (CDP) conjugate of the payload camptothecin (CPT). The individual polymer strands self-assemble into nanoparticles (ca. five strands) of approximately 10 to 40 nm diameter and 10 wt% CPT by multiple, interstrand, inclusion complex formation between the cyclodextrin and the CPT molecules. CRLX101 is currently being investigated in phase II trials in patients with renal, ovarian and rectal cancer. Methods: A phase I clinical trial was performed with CRLX101 at the City of Hope, in patients with advanced or metastatic stomach, gastroesophageal or esophageal cancer. This study was sponsored by City of Hope Medical Center, and funding and CRLX101 was provided by Cerulean Pharma Inc. (ClinicalTrials.gov identifier: NCT01612546). The goal of this study was to test the hypothesis that intact CRLX101 nanoparticles deposit in human tumors and not in normal adjacent tissue after intravenous administration. Tumor and adjacent healthy tissue biopsies were obtained through endoscopic capture from patients who received CRLX101, and analyzed via a number of methodologies. Results: Both the pre- and post-dosing, healthy tissue samples adjacent to tumors show no evidence of either the NDC or the payload (CPT) contained within the NDC. Similar results are obtained from the pre-dosing tumor samples. However, in 8 of 9 patients that were evaluated, CPT is detected in the tumor tissue by fluorescent microscopy examination of fixed sections. For 3 of these patients, proof of intact CRLX101 NDC is obtained from tissue sections by colocalized, fluorescence from the CPT and a secondary antibody used to stain a PEG specific antibody (binds to the PEG in CRLX101). Following fluorescence imaging, remaining tissues from 3 patients were homogenized and measured for free and CDP conjugated CPT using HPLC. CPT was present in the post-treatment tumor tissue of all 3 patient samples with an average of 96.2±13.1% in the conjugated form, indicating that CRLX101 NDCs are localized in these samples. Conclusions: Tumor and adjacent healthy tissue biopsies obtained from cancer patients who have received CRLX101show that these NDCs do localize in human tumors and not in adjacent tissues. Citation Format: Andrew Clark, Devin T. Wiley, Jonathan E. Zuckerman, Paul Webster, Joseph Chao, James Lin, Yun Yen, Mark E. Davis, Scott Eliasof. CRLX101, an investigational nanoparticle-drug conjugate, localizes in human tumors and not in adjacent healthy tissue after intravenous dosing. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B33.

Abstract B37: Selective tumor localization of CRLX101, a novel nanoparticle-drug conjugate

Abstract CRLX101, an investigational nanoparticle-drug conjugate (NDC) containing the payload camptothecin conjugated to a biocompatible copolymer of cyclodextrin and polyethylene glycol (PEG), is currently being evaluated clinically in multiple treatment-refractory solid tumors. CRLX101 is a dual inhibitor of topoisomerase 1 (TOPO 1) and hypoxia-inducible factor 1α (HIF-1α) and has been shown pre-clinically to be active in many different tumor types. It has a long circulation half-life and is believed to release camptothecin in a slow and prolonged fashion in the tumor. Camptothecin is an active anti-tumor agent preclinically but was not developed clinically due to its poor tolerability in patients. The development of CRLX101, which has not demonstrated significant toxicity in over 250 patients dosed to date, offers a unique opportunity to improve cancer treatment in a meaningful way. We have previously published that in gastric cancer patients treated with CRLX101, camptothecin fluorescence can be visualized in tumor tissue but not adjoining normal tissue. Based on these data we hypothesized that CRLX101 utilizes the enhanced permeability and retention (EPR) effect to accumulate selectively in tumors. In this study, we sought to mechanistically dissect the process of CRLX101 entry and accumulation into tumor cells using multiple methods, both in vitro and in xenograft tumors in vivo. Using confocal microscopy, we can detect camptothecin fluorescence in CRLX101- treated tumor cells in culture as well as in tumor tissue from mice treated with CRLX101. We can co-localize this camptothecin with intact nanoparticles using an anti-PEG antibody that specifically detects the PEG loops in the NDCs. We can also demonstrate that macropinocytosis plays a role in the manner by which tumor cells take up CRLX101. Using an anti-CD31 antibody, we can visualize the distance traversed by CRLX101 from the tumor vasculature over time. We have developed novel analytical methods to precisely quantify both released and CRLX101-conjugated camptothecin over time in CRLX101 treated tumor cells in vitro, as well as in tumor tissue from mice treated with CRLX101 in vivo. Using cell viability assays, we can correlate the kinetics of camptothecin released inside tumor cells to the degree of tumor cell kill. We believe that these data are an important step forward in understanding the precise mechanism(s) underlying selective delivery of CRLX101 into tumor tissue. Citation Format: Christian G. Peters, Douglas Lazarus, Donna Brown, Ningning Zhang, Roy Case, Ellen Rohde, Scott Eliasof, Lata Jayaraman. Selective tumor localization of CRLX101, a novel nanoparticle-drug conjugate. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B37.

Abstract 1384: CRLX101, an investigational camptothecin-containing nanoparticle-drug conjugate, reverses the HIF-1α-mediated increase in cancer stem cells caused by bevacizumab in a preclinical model of triple-negative breast cancer

Abstract Antiangiogenic agents are designed to impede the development of new tumor blood vessels, thereby starving tumors of oxygen and nutrients to ultimately block tumor growth. Despite advances made in developing antiangiogenic therapies, clinical and preclinical data suggest that these drugs have limited efficacy in breast cancer patients. Tumors inevitably develop resistance to antiangiogenic agents and patients frequently fail to demonstrate significantly better overall survival. Acquired resistance to antiangiogenic agents has been attributed in part to the induction of intra-tumoral hypoxia and the concomitant stabilization of hypoxia-inducible factor 1α (HIF-1α), a transcription factor that promotes tumor angiogenesis, invasion, metastasis, and cancer stem cell (CSC) self-renewal. In this preclinical model, we demonstrate that CRLX101, an investigational nanoparticle-drug conjugate (NDC) containing the payload camptothecin (CPT), can reverse the stimulatory effects of hypoxia on the CSC population in an orthotopic triple-negative xenograft model. The payload, camptothecin, a topoisomerase 1 inhibitor, inhibits HIF-1α protein accumulation at concentrations below those that were cytotoxic to tumor cells, and inhibits hypoxia-mediated CSC induction at these low concentrations in vitro. In an orthotopic triple-negative breast cancer model, CRLX101 is synergistic with bevacizumab. Tumor reimplantation experiments confirm that the combination therapy effectively targets both the bulk tumor cell and CSC populations. Results generated from these preclinical studies support the clinical research of combining antiangiogenic agents with CRLX101 to increase patient survival. CRLX101 is currently in phase 2 clinical trials in combination with bevacizumab in both recurrent ovarian cancer and metastatic renal cell carcinoma. Citation Format: Sarah J. Conley, Trenton L. Baker, Joseph P. Burnet, Rebecca L. Thiesen, Douglas Lazarus, Christian G. Peters, Shawn G. Clouthier, Scott Eliasof, Max S. Wicha. CRLX101, an investigational camptothecin-containing nanoparticle-drug conjugate, reverses the HIF-1α-mediated increase in cancer stem cells caused by bevacizumab in a preclinical model of triple-negative breast cancer. [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 1384. doi:10.1158/1538-7445.AM2015-1384

Abstract 5515: Neoadjuvant chemoradiotherapy for rectal cancer with CRLX101, an investigational nanoparticle-drug conjugate with a camptothecin payload

Abstract Background: There has been great interest in developing novel agents and strategies to improve chemoradiotherapy (CRT) for locally advanced rectal cancer. Irinotecan, a campothecin (CPT) analogue, held high potential, but the combination was clinically infeasible due to severe gastrointestinal toxicities. CRLX101, is an investigational nanoparticle drug conjugate (NDC). Preclinical experiments showed that CRLX101 differentially delivers CPT into cancer cells and appears to durably suppress HIF-1α as well as topoisomerase 1, but with less gastrointestinal toxicities than irinotecan. We therefore hypothesized that the addition of CRLX101 to rectal CRT (5-FU + XRT) may further improve the therapeutic index in this setting. Methods: Synergy with CRLX101 in combination with either XRT or CRT was studied in vitro (SW480 and HT29 colorectal cancer cell lines) and in vivo (murine flank xenograft models). Skin toxicity and hematologic toxicity were also characterized. In order to test the synergy hypothesis in the clinic, a Phase Ib/II clinical trial (LCCC1315) evaluating the addition of CRLX101 to CRT in the neo-adjuvant treatment of rectal cancer is currently underway. A standard 3 + 3 design is being employed for the phase Ib with a CRLX101 starting dose of 12 mg/m2 in the first cohort escalating to the CRLX101 monotherapy MTD of 15 mg/m2 in the second. The primary phase 2 end-point is the pathological complete response (pCR) rate from treatment. Results: CRLX101 was found to be as potent as camptothecin in vitro. We have demonstrated that CRLX101 functions by inhibition of both DNA repair and HIF-1α signaling. The addition of CRLX101 to radiotherapy increased and prolonged the number of γH2AX foci, even at 24 hours post radiotherapy. We also confirmed that CRLX101 decreased HIF-1α and its downstream targets VEGF and carbonic anhydrase IX in mice bearing HT29 xenografts. Our findings were further validated in vivo: we demonstrated that both CRLX101+5FU+XRT and CRLX101+XRT delayed tumor growth more than other regimens (p-values < 0.05). More importantly, we found CRT with CRLX101+5FU is significantly more effective than CRT with oxaliplatin+5FU (25 days to double tumor volume vs. 11 days), a regimen that has been extensively studied clinically. Preclinical toxicity studies demonstrated that the addition of CRLX101 did not increase hematologic or skin toxicities. In the ongoing clinical trial, none of the first 6 patients enrolled have experienced dose-limiting toxicities, and 1 out of 3 patients who underwent surgery had a pCR. The other 2 patients had extensive treatment response with minimal residual tumor. Conclusions: Preclinical data suggests that CRLX101 improves the therapeutic index of CRT for rectal cancer. Preliminary clinical data is encouraging, and supports further clinical assessment of CRLX101+5FU+XRT in patients with locally advanced rectal cancer. Citation Format: XI TIAN, Minh Nguyen, Henry Foote, Kyle T. Wagner, Hanna K. Sanoff, Autumn J. McRee, Bert H. O'Neil, Benjamin F. Calvo, William A. Blackstock, Joel E. Tepper, Edward Garmey, Scott Eliasof, Andrew Z. Wang. Neoadjuvant chemoradiotherapy for rectal cancer with CRLX101, an investigational nanoparticle-drug conjugate with a camptothecin payload. [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 5515. doi:10.1158/1538-7445.AM2015-5515

Abstract 4124: Potent anti-tumor and metastatic breast cancer efficacy of bevacizumab with CRLX101, an investigational chemotherapy nanoparticle-drug conjugate that secondarily suppresses HIF-1α

Abstract Despite the approval of seven different VEGF-pathway targeting agents, such as bevacizumab, for ten different cancer types, VEGF inhibition has shown only modest survival benefits - especially in breast cancer. One hypothesis for this is the adaptive resistance that emerges, such as increased tumor hypoxia and elevated hypoxia-inducible factor 1α (HIF-1α), which up-regulates genes causing tumor angiogenesis, resistance and metastasis. Here we evaluated bevacizumab paired with a potent cytotoxic investigational drug called CRLX101, a nanoparticle-drug conjugate containing the payload camptothecin that secondarily suppresses HIF-1α. In a preclinical mouse model of primary human breast tumor xenografts grown in the mammary fat pad after cell-line implantation, CRLX101 monotherapy was highly efficacious. More importantly, CRLX101 with bevacizumab resulted in dramatic primary tumor shrinkages and greatly improved mice survival, despite bevacizumab alone having no activity in this model. This potent anti-tumor efficacy was further confirmed in a patient-derived xenograft (PDX) model, where again CRLX101 and bevacizumab led to obvious shrinkage of established primary tumors. HIF-1α suppression was confirmed by immunohistochemistry while changes in tumor hypoxia and perfusion were evaluated using photoacoustic imaging and contrast-enhanced ultrasound, respectively. To better reflect the clinical treatment setting, the combination was next evaluated in our preclinical model of post-surgical, overt metastatic disease. Both CRLX101 monotherapy and CRLX101 in combination with bevacizumab showed shrinkage of existing metastatic masses and prevented the emergence of new metastases. In conclusion, we showed that pairing an anti-angiogenic agent with a potent chemotherapy backbone that is able to suppress HIF-1α up-regulation induced by anti-angiogenic therapy greatly improve efficacy in both primary and metastatic breast cancer models. The data from these preclinical experiments demonstrate that further research of the combination of bevacizumab and other anti-angiogenic drugs with CRLX101 is warranted in solid tumors. Citation Format: Elizabeth Pham, Christina R. Lee, Ping Xu, Shan Man, Melissa Yin, F. Stuart Foster, Christian G. Peters, Douglas Lazarus, Scott Eliasof, Robert S. Kerbel. Potent anti-tumor and metastatic breast cancer efficacy of bevacizumab with CRLX101, an investigational chemotherapy nanoparticle-drug conjugate that secondarily suppresses HIF-1α. [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 4124. doi:10.1158/1538-7445.AM2015-4124

CRLX101, an investigational camptothecin-containing nanoparticle-drug conjugate, targets cancer stem cells and impedes resistance to antiangiogenic therapy in mouse models of breast cancer.

Antiangiogenic therapies inhibit the development of new tumor blood vessels, thereby blocking tumor growth. Despite the advances in developing antiangiogenic agents, clinical data indicate that these drugs have limited efficacy in breast cancer patients. Tumors inevitably develop resistance to antiangiogenics, which is attributed in part to the induction of intra-tumoral hypoxia and stabilization of hypoxia-inducible factor 1α (HIF-1α), a transcription factor that promotes tumor angiogenesis, invasion, metastasis, and cancer stem cell (CSC) self-renewal. Here, we tested whether inhibiting HIF-1α can reverse the stimulatory effects of antiangiogenic-induced hypoxia on breast CSCs. Breast cancer cells grown under hypoxic conditions were treated with the dual topoisomerase-1 (TOPO-1) and HIF-1α inhibitor camptothecin and assessed for their CSC content. In a preclinical model of breast cancer, treatment with bevacizumab was compared to the combination treatment of bevacizumab with CRLX101, an investigational nanoparticle-drug conjugate with a camptothecin payload or CRLX101 monotherapy. While exposure to hypoxia increased the number of breast CSCs, treatment with CPT blocked this effect. In preclinical mouse models, concurrent administration of CRLX101 impeded the induction of both HIF-1α and CSCs in breast tumors induced by bevacizumab treatment. Greater tumor regression and delayed tumor recurrence were observed with the combination of these agents compared to bevacizumab alone. Tumor reimplantation experiments demonstrated that the combination therapy effectively targets the CSC populations. The results from these studies support the combined administration of dual TOPO-1- and HIF-1α-targeted agents like CRLX101 with antiangiogenic agents to increase the efficacy of these treatments.