Cancer ‘vaccine’ eliminates tumors in mice

Cancer ‘vaccine’ eliminates tumors in mice

January 31, 2018
Stanford University Medical Center
Injecting minute amounts of two immune-stimulating agents directly into solid tumors in mice can eliminate all traces of cancer in the animals, including distant, untreated metastases, according to a new study.

Ronald Levy (left) and Idit Sagiv-Barfi led the work on a possible cancer treatment that involves injecting two immune-stimulating agents directly into solid tumors.
Credit: Steve Fisch

Injecting minute amounts of two immune-stimulating agents directly into solid tumors in mice can eliminate all traces of cancer in the animals, including distant, untreated metastases, according to a study by researchers at the Stanford University School of Medicine.

The approach works for many different types of cancers, including those that arise spontaneously, the study found.
The researchers believe the local application of very small amounts of the agents could serve as a rapid and relatively inexpensive cancer therapy that is unlikely to cause the adverse side effects often seen with bodywide immune stimulation.
“When we use these two agents together, we see the elimination of tumors all over the body,” said Ronald Levy, MD, professor of oncology. “This approach bypasses the need to identify tumor-specific immune targets and doesn’t require wholesale activation of the immune system or customization of a patient’s immune cells.”
One agent is currently already approved for use in humans; the other has been tested for human use in several unrelated clinical trials. A clinical trial was launched in January to test the effect of the treatment in patients with lymphoma.
Levy, who holds the Robert K. and Helen K. Summy Professorship in the School of Medicine, is the senior author of the study, which will be published Jan. 31 in Science Translational Medicine. Instructor of medicine Idit Sagiv-Barfi, PhD, is the lead author.
‘Amazing, bodywide effects’
Levy is a pioneer in the field of cancer immunotherapy, in which researchers try to harness the immune system to combat cancer. Research in his laboratory led to the development of rituximab, one of the first monoclonal antibodies approved for use as an anticancer treatment in humans.

Some immunotherapy approaches rely on stimulating the immune system throughout the body. Others target naturally occurring checkpoints that limit the anti-cancer activity of immune cells. Still others, like the CAR T-cell therapy recently approved to treat some types of leukemia and lymphomas, require a patient’s immune cells to be removed from the body and genetically engineered to attack the tumor cells. Many of these approaches have been successful, but they each have downsides — from difficult-to-handle side effects to high-cost and lengthy preparation or treatment times.
“All of these immunotherapy advances are changing medical practice,” Levy said. “Our approach uses a one-time application of very small amounts of two agents to stimulate the immune cells only within the tumor itself. In the mice, we saw amazing, bodywide effects, including the elimination of tumors all over the animal.”
Cancers often exist in a strange kind of limbo with regard to the immune system. Immune cells like T cells recognize the abnormal proteins often present on cancer cells and infiltrate to attack the tumor. However, as the tumor grows, it often devises ways to suppress the activity of the T cells.
Levy’s method works to reactivate the cancer-specific T cells by injecting microgram amounts of two agents directly into the tumor site. (A microgram is one-millionth of a gram). One, a short stretch of DNA called a CpG oligonucleotide, works with other nearby immune cells to amplify the expression of an activating receptor called OX40 on the surface of the T cells. The other, an antibody that binds to OX40, activates the T cells to lead the charge against the cancer cells. Because the two agents are injected directly into the tumor, only T cells that have infiltrated it are activated. In effect, these T cells are “prescreened” by the body to recognize only cancer-specific proteins.

Cancer-destroying rangers
Some of these tumor-specific, activated T cells then leave the original tumor to find and destroy other identical tumors throughout the body.
The approach worked startlingly well in laboratory mice with transplanted mouse lymphoma tumors in two sites on their bodies. Injecting one tumor site with the two agents caused the regression not just of the treated tumor, but also of the second, untreated tumor. In this way, 87 of 90 mice were cured of the cancer. Although the cancer recurred in three of the mice, the tumors again regressed after a second treatment. The researchers saw similar results in mice bearing breast, colon and melanoma tumors.
Mice genetically engineered to spontaneously develop breast cancers in all 10 of their mammary pads also responded to the treatment. Treating the first tumor that arose often prevented the occurrence of future tumors and significantly increased the animals’ life span, the researchers found.
Finally, Sagiv-Barfi explored the specificity of the T cells by transplanting two types of tumors into the mice. She transplanted the same lymphoma cancer cells in two locations, and she transplanted a colon cancer cell line in a third location. Treatment of one of the lymphoma sites caused the regression of both lymphoma tumors but did not affect the growth of the colon cancer cells.
“This is a very targeted approach,” Levy said. “Only the tumor that shares the protein targets displayed by the treated site is affected. We’re attacking specific targets without having to identify exactly what proteins the T cells are recognizing.”
The current clinical trial is expected to recruit about 15 patients with low-grade lymphoma. If successful, Levy believes the treatment could be useful for many tumor types. He envisions a future in which clinicians inject the two agents into solid tumors in humans prior to surgical removal of the cancer as a way to prevent recurrence due to unidentified metastases or lingering cancer cells, or even to head off the development of future tumors that arise due to genetic mutations like BRCA1 and 2.
“I don’t think there’s a limit to the type of tumor we could potentially treat, as long as it has been infiltrated by the immune system,” Levy said.
The work is an example of Stanford Medicine’s focus on precision health, the goal of which is to anticipate and prevent disease in the healthy and precisely diagnose and treat disease in the ill.

Story Source:
Materials provided by Stanford University Medical Center. Original written by Krista Conger. Note: Content may be edited for style and length.

Journal Reference:

Idit Sagiv-Barfi, Debra K. Czerwinski, Shoshana Levy, Israt S. Alam, Aaron T. Mayer, Sanjiv S. Gambhir, Ronald Levy. Eradication of spontaneous malignancy by local immunotherapy. Science Translational Medicine, 2018; 10 (426): eaan4488 DOI: 10.1126/scitranslmed.aan4488


Aspirin may strengthen anti-cancer drugs

December 07, 2017
Top News in Oncology #5 of 6

Healthline/Medical News Today

Adding aspirin to a particular cancer medication increases its effectiveness against some cancers. These latest findings offer hope for individuals with certain difficult-to-treat cancers.
Finding a “cure” for cancer is the Holy Grail of medical research. However, a single catch-all solution is unlikely; cancer comes in many shapes and forms.
Each type of cancer involves different cell types and cellular environments, mutations in a range of genes, and alterations to the way specific cells function; this makes understanding and treating cancer a complex battle.
Some researchers have referred to cancer as a “constellation” of diseases.
One particular type of cancer, which has mutations in a set of genes called RAS, is a particularly challenging type to treat.
Cancers with RAS mutations include some pancreatic, colorectal, and lung cancers, and a small number of melanomas; they have low survival rates. Currently, there are no pharmaceuticals specifically designed to target RAS mutant cancers.
One drug—Sorafenib—showed “marginal” benefits in a multicenter Phase 3 trial for one type of lung cancer. However, side effects were significant, causing some patients to drop out of the trial early.
Aspirin and cancer
Aspirin, or acetylsalicylic acid, has been used in one form or another since ancient times. For instance, Hippocrates referred to the use of salicylic tea to reduce fevers around 400 B.C. Aspirin is still used to treat a range of medical complaints.
Today, it is available over the counter and used to relieve pain and reduce fever. It is also prescribed to individuals who have had heart attacks and strokes as it significantly reduces the risk of another cardiovascular event.
Other research has found that aspirin has certain anti-cancer effects; this protective action seems particularly pronounced in colorectal cancers.
With this relationship in mind, scientists from the University of Queensland in Australia recently set out to investigate whether adding aspirin to Sorafenib could increase its potency in cancers with RAS mutations.
The research team, led by Associate Professor Helmut Schaider, published their results this week in the journal Clinical Cancer Research. Using a mouse model, the results were encouraging.

“We found the addition of aspirin to a cancer inhibitor drug, Sorafenib, strongly enhanced its effectiveness against mouse models of lung cancer and melanoma with RAS mutations.”
Dr. Helmut Schaider

Drilling down into the details, the scientists examined the molecular mechanisms that facilitated aspirin’s positive effects. Dr. Schaider explains how the addition of a relatively high aspirin dose appears to improve outcomes:
“Two molecular processes are activated and together they work to kill RAS mutant cancer cells. This dual activation also might prevent the tumors acquiring resistance to the treatment, which can happen when the inhibitor drug is given alone.”
The future of Sorafenib and aspirin
The researchers believe that taking the drugs in combination may mean that patients could take Sorafenib in smaller doses, reducing the negative consequences of side effects.
The combination has the potential to extend the length of time cancer patients have without the disease progressing. Dr. Schaider says that “adding aspirin could also potentially prevent relapse of tumors in patients.”
The next step is to investigate whether this positive interaction can be demonstrated in human patients; hopefully, follow-up work will not be too far down the line, as Dr. Schaider says:
“A clinical trial of the combination could proceed relatively quickly, potentially piggy-backing on other testing already underway.”
However, the adverse effects of taking high doses of aspirin would need to be managed; for instance, the chance of excessive bleeding is increased. For individuals with no other treatment options, however, the negative impacts of aspirin would be outweighed by the benefits.
Work is already underway to understand whether aspirin in conjunction with other cancer drugs might increase outcomes. If aspirin can impart a genuine benefit, it would be a significant and cost-effective step forward in cancer treatment.

Hsp90 in Cancer: Beyond the Usual Suspects

Gaurav Garg, … Brian S.J. Blagg1, in Advances in Cancer Research, 2016
Withaferin A, a Disruptor of Hsp90–Cdc37 Interaction
Withaferin A (WA, Fig. 13) is a withanolide isolated from the Indian medicinal plant of Withania somnifera (commonly known as “Ashwagandha” or “Indian Winter Cherry” in Ayurvedic medicine) and possesses diverse biological activities, such as anti-inflammatory (Kaileh et al., 2007), antistress, antioxidant, immunomodulatory (Mishra, Singh, & Dagenais, 2000), antiangiogenesis (Mohan et al., 2004), and anticancer activities (Yang, Shi, & Dou, 2007). Since its discovery in the late 1960s, withaferin A has been extensively studied for its anticancer activity, and numerous mechanisms and molecular targets proposed (Falsey et al., 2006; Kaileh et al., 2007; Shohat, Gitter, Abraham, & Lavie, 1967; Srinivasan, Ranga, Burikhanov, Han, & Chendil, 2007; Yang et al., 2007; Yokota, Bargagna-Mohan, Ravindranath, Kim, & Mohan, 2006). It has been reported that withaferin A inhibits nuclear factor-κB (NF-κB) activation of IκB kinase via a thioalkylation-sensitive redox mechanism (Kaileh et al., 2007) induces apoptosis in prostate cancer cells through Par-4 induction (Srinivasan et al., 2007), targets β5 subunit of tumor proteasome (Yang et al., 2007), and covalently binds to Annexin II to alter cytoskeletal architecture (Falsey et al., 2006). In 2010, Yu and coworkers demonstrated that withaferin A exhibits antiproliferative activity and inhibits Hsp90 in pancreatic cells where it was reported to deplete cellular levels of Hsp90-dependent client proteins (Akt, Cdk4, and GR) (Yu et al., 2010). In addition, it was observed that withaferin A induces Hsp70 expression, without affecting Hsp90 levels. Moreover, these researchers found that withaferin A binds Hsp90 and halts the Hsp90 chaperone cycle through a novel ATP-independent mechanism. To identify the domain to which withaferin A binds in Hsp90, a pull-down assay using WA-biotin was used, which suggested interaction with the chaperone’s C-terminal domain (Yu et al., 2010). Coimmunoprecipitation studies showed that withaferin A disrupts formation of the Hsp90/Cdc37 complex in pancreatic cancer cells (Yu et al., 2010). Structure–activity relationship studies have identified a pharmacophore of WA that involves the 4-hydroxy-5,6-epoxy-22-en-1-one moiety and its unsaturated lactone as critical for cytotoxic activity (Mohan et al., 2004; Yousuf et al., 2011). Recent studies with the withanolides indicate that the 5,6-epoxide may react with reactive cysteine residues in Hsp90 and induce aggregation, leading to disruption of Hsp90 function (Gu et al., 2014).

Mol Carcinog. 2015 Jun;54(6):417-29. doi: 10.1002/mc.22110. Epub 2013 Nov 30. Withaferin A inhibits experimental epithelial-mesenchymal transition in MCF-10A cells and suppresses vimentin protein level in vivo in breast tumors.

Lee J1, Hahm ER, Marcus AI, Singh SV.

Author information

Department of Pharmacology & Chemical Biology, and University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.


We have shown previously that withaferin A (WA), a bioactive component of the medicinal plant Withania somnifera, inhibits growth of cultured and xenografted human breast cancer cells and prevents breast cancer development and pulmonary metastasis incidence in a transgenic mouse model. The present study was undertaken to determine if the anticancer effect of WA involved inhibition of epithelial-mesenchymal transition (EMT). Experimental EMT induced by exposure of MCF-10A cells to tumor necrosis factor-α (TNF-α) and transforming growth factor-β1 (TGF-β) was partially reversed by treatment with WA but not by its structural analogs withanone or withanolide A. Combined TNF-α and TGF-β treatments conferred partial protection against MCF-10A cell migration inhibition by WA. Inhibition of TNF-α and TGF-β-induced MCF-10A cell migration by WA exposure was modestly attenuated by knockdown of E-cadherin protein. MCF-7 and MDA-MB-231 cells exposed to WA exhibited sustained (MCF-7) or transient (MDA-MB-231) induction of E-cadherin protein. On the other hand, the level of vimentin protein was increased markedly after 24 h treatment of MDA-MB-231 cells with WA. WA-induced apoptosis was not affected by vimentin protein knockdown in MDA-MB-231 cells. Protein level of vimentin was significantly lower in the MDA-MB-231 xenografts as well as in MMTV-neu tumors from WA-treated mice compared with controls. The major conclusions of the present study are that (a) WA treatment inhibits experimental EMT in MCF-10A cells, and (b) mammary cancer growth inhibition by WA administration is associated with suppression of vimentin protein expression in vivo.

EMT; breast cancer; vimentin; withaferin A

PMID:   24293234

PMCID:   PMC4039625

DOI:   10.1002/mc.22110

Chem Biol. 2007 Jun;14(6):623-34. The tumor inhibitor and antiangiogenic agent withaferin A targets the intermediate filament protein vimentin.

Bargagna-Mohan P1, Hamza A, Kim YE, Khuan Abby Ho Y, Mor-Vaknin N, Wendschlag N, Liu J, Evans RM, Markovitz DM, Zhan CG, Kim KB, Mohan R.

Author information

Department of Ophthalmology and Visual Sciences, University of Kentucky, Lexington, KY 40536, USA.


The natural product withaferin A (WFA) exhibits antitumor and antiangiogenesis activity in vivo, which results from this drug’s potent growth inhibitory activities. Here, we show that WFA binds to the intermediate filament (IF) protein, vimentin, by covalently modifying its cysteine residue, which is present in the highly conserved alpha-helical coiled coil 2B domain. WFA induces vimentin filaments to aggregate in vitro, an activity manifested in vivo as punctate cytoplasmic aggregates that colocalize vimentin and F-actin. WFA’s potent dominant-negative effect on F-actin requires vimentin expression and induces apoptosis. Finally, we show that WFA-induced inhibition of capillary growth in a mouse model of corneal neovascularization is compromised in vimentin-deficient mice. These findings identify WFA as a chemical genetic probe of IF functions, and illuminate a potential molecular target for withanolide-based therapeutics for treating angioproliferative and malignant diseases.

PMID:   17584610

PMCID:   PMC3228641

DOI:   10.1016/j.chembiol.2007.04.010

Free PMC Article

“A vimentin-binding small molecule leads to mitotic disruption in mesenchymal cancer cells

“A vimentin-binding small molecule leads to mitotic disruption in mesenchymal cancer cells”

November 10, 2017
Top News in Oncology #7 of 20

Researchers discover promising new anticancer strategy
Scripps Research Institute News

Scientists at The Scripps Research Institute (TSRI) have discovered a compound that in laboratory tests irreversibly stops the growth of certain aggressive, treatment-resistant tumor cells. If successfully developed into a treatment, the compound would be the first of a new class of anticancer drugs.

In their study, published in the Proceedings of the National Academy of Sciences journal, the TSRI researchers showed that the new compound, FiVe1, blocks the growth of tumor cells that have undergone what researchers call the epithelial-mesenchymal transition (EMT), a process common in breast, colon, lung and other epithelial cell-derived tumors.

FiVe1 also , that is blocks the growth of tumors called sarcomas, which originate from mesenchymal tissues including bone, fat, cartilage, muscle and blood vessels. The compound blocks mitosis by binding to a structural protein, vimentinroduced abundantly in mesenchymal-type cells. Drugs that work via this mechanism should spare many of the healthy, fast-dividing cells, such as hair follicle cells, that are harmed by standard chemotherapy drugs.

“We hope that this discovery is going to lead to the development of effective therapies against a broad range of aggressive cancers,” said principal investigator Luke Lairson, PhD, assistant professor of chemistry at TSRI.

Mesenchymal cells are one of the major cell types in developing embryos, and ultimately give rise to bone, muscle, fat, and certain other tissues. The EMT occurs naturally in early development to turn some epithelial cells—another broad cell type—into more free-ranging mesenchymal cells. The EMT also can be triggered by inflammation in adult tissues to transform epithelial cells into stem-like mesenchymal cells that aid wound healing.

The vast majority of cancer deaths are ultimately caused by recurrence following therapy or metastases. In previous studies, scientists had demonstrated that the EMT process enables carcinoma cells to adopt the properties of cancer stem cells, namely chemotherapy resistance and the ability to migrate in the body to form metastases.

Researchers have become aware in just the last decade that breast, colon and other epithelial-derived tumor cells sometimes exploit the EMT to detach from a primary tumor and acquire stem-like properties. Whether they originate from EMT-transformed epithelial cells or from mesenchymal tissues, mesenchymal cancer cells are prone to form deadly metastases and are generally difficult to treat with drugs—surgical removal is often the only good option.

The TSRI researchers, including lead author Michael J. Bollong, PhD, currently a Scripps Fellow in the Department of Chemistry, discovered FiVe1 by screening a library of about 50,000 small-molecule compounds for activity against EMT-transformed breast cancer cells. The engineered cell line was developed by collaborating researcher Sendurai A. Mani, PhD, of MD Anderson Cancer Center at the University of Texas. The cells express FOXC2, a transcription factor gene that promotes the EMT and makes cancer cells more stem-like, more prone to metastasis and more resistant to treatment.

One compound performed particularly well at curbing the growth of the FOXC2-expressing cells without affecting non-FOXC2-expressing cells, and had other properties that make it potentially suitable as a small-molecule drug. Follow-up molecular biology studies revealed that the compound blocks mitosis in the FOXC2-expressing cancer cells by binding to a structural protein called vimentin, produced principally in mesenchymal cell types. The compound, in addition to blocking mitosis, caused EMT-transformed breast cancer cells to quickly revert to a lower-grade, epithelial appearance. Lairson and colleagues named the compound FOXC2-inhibiting Vimentin effector 1 (FiVe1).

“Traditional anti-mitosis drugs target proteins such as microtubules that are basic features of the cell division apparatus,” Bollong said. “We’ve shown for the first time here that targeting an intermediate filament protein such as vimentin can also induce ‘mitotic catastrophe.’”

Further lab-dish tests showed that FiVe1 irreversibly blocks mitosis in several other EMT-transformed cancer cell lines, as well as in tumor cells originating from muscle, fat, cartilage and other mesenchymal tissues.

FiVe1’s selectivity for vimentin-containing mesenchymal cancer cells means that it wouldn’t have the same side-effects as traditional chemotherapy drugs. Vimentin is not expressed at significant levels in the hair follicle cells and mouth- and gut-lining epithelial cells damaged by standard chemotherapy drugs. “A drug that blocks mitosis by targeting vimentin should be less toxic than traditional chemotherapeutic drugs that targets cell-division,” Lairson said. He and his colleagues envision future drugs based on this strategy being used against carcinomas as add-on therapies to suppress EMT-transformed tumor cells that are prone to metastasize. Against sarcomas—tumors that are entirely mesenchymal—anti-vimentin drugs could be primary therapies.

The researchers currently are working to optimize FiVe1 and a few other promising compounds with chemical modifications. With help from a new National Institutes of Health grant they also are screening larger compound libraries to find other potential drug compounds that selectively attack mesenchymal and EMT-transformed cancers. The team plans to begin tests in animal models of cancer once they have an optimized compound.

Broad targeting of angiogenesis for cancer prevention and therapy

Semin Cancer Biol. 2015 Dec;35 Suppl:S224-S243. doi: 10.1016/j.semcancer.2015.01.001. Epub  2015 Jan 16.
Broad targeting of angiogenesis for cancer prevention and therapy.
Wang Z1, Dabrosin C2, Yin X3, Fuster MM3, Arreola A4, Rathmell WK4, Generali D5, Nagaraju GP6, El-Rayes B6, Ribatti D7, Chen YC8, Honoki K9, Fujii H9, Georgakilas AG10, Nowsheen S11, Amedei A12, Niccolai E12, Amin A13, Ashraf SS14, Helferich B15, Yang X15, Guha G16, Bhakta D16, Ciriolo MR17, Aquilano K17, Chen S18, Halicka D19, Mohammed SI20, Azmi AS21, Bilsland A22, Keith WN22, Jensen LD23.

Author information                                                       Free PMC Article


Deregulation of angiogenesis–the growth of new blood vessels from an existing vasculature–is a main driving force in many severe human diseases including cancer. As such, tumor angiogenesis is important for delivering oxygen and nutrients to growing tumors, and therefore considered an essential pathologic feature of cancer, while also playing a key role in enabling other aspects of tumor pathology such as metabolic deregulation and tumor dissemination/metastasis. Recently, inhibition of tumor angiogenesis has become a clinical anti-cancer strategy in line with chemotherapy, radiotherapy and surgery, which underscore the critical importance of the angiogenic switch during early tumor development. Unfortunately the clinically approved anti-angiogenic drugs in use today are only effective in a subset of the patients, and many who initially respond develop resistance over time. Also, some of the anti-angiogenic drugs are toxic and it would be of great importance to identify alternative compounds, which could overcome these drawbacks and limitations of the currently available therapy. Finding “the most important target” may, however, prove a very challenging approach as the tumor environment is highly diverse, consisting of many different cell types, all of which may contribute to tumor angiogenesis. Furthermore, the tumor cells themselves are genetically unstable, leading to a progressive increase in the number of different angiogenic factors produced as the cancer progresses to advanced stages. As an alternative approach to targeted therapy, options to broadly interfere with angiogenic signals by a mixture of non-toxic natural compound with pleiotropic actions were viewed by this team as an opportunity to develop a complementary anti-angiogenesis treatment option. As a part of the “Halifax Project” within the “Getting to know cancer” framework, we have here, based on a thorough review of the literature, identified 10 important aspects of tumor angiogenesis and the pathological tumor vasculature which would be well suited as targets for anti-angiogenic therapy: (1) endothelial cell migration/tip cell formation, (2) structural abnormalities of tumor vessels, (3) hypoxia, (4) lymphangiogenesis, (5) elevated interstitial fluid pressure, (6) poor perfusion, (7) disrupted circadian rhythms, (8) tumor promoting inflammation, (9) tumor promoting fibroblasts and (10) tumor cell metabolism/acidosis. Following this analysis, we scrutinized the available literature on broadly acting anti-angiogenic natural products, with a focus on finding qualitative information on phytochemicals which could inhibit these targets and came up with 10 prototypical phytochemical compounds: (1) oleanolic acid, (2) tripterine, (3) silibinin, (4) curcumin, (5) epigallocatechin-gallate, (6) kaempferol, (7) melatonin, (8) enterolactone, (9) withaferin A and (10) resveratrol. We suggest that these plant-derived compounds could be combined to constitute a broader acting and more effective inhibitory cocktail at doses that would not be likely to cause excessive toxicity. All the targets and phytochemical approaches were further cross-validated against their effects on other essential tumorigenic pathways (based on the “hallmarks” of cancer) in order to discover possible synergies or potentially harmful interactions, and were found to generally also have positive involvement in/effects on these other aspects of tumor biology. The aim is that this discussion could lead to the selection of combinations of such anti-angiogenic compounds which could be used in potent anti-tumor cocktails, for enhanced therapeutic efficacy, reduced toxicity and circumvention of single-agent anti-angiogenic resistance, as well as for possible use in primary or secondary cancer prevention strategies.
Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Angiogenesis; Anti-angiogenic; Cancer; Phytochemicals; Treatment

PMID:   25600295
Free PMC Article

PMCID:   PMC4737670