(cid:39)(cid:82)(cid:90)(cid:81)(cid:79)(cid:82)(cid:68)(cid:71)(cid:72)(cid:71)(cid:3)(cid:73)(cid:85)(cid:82)(cid:80)(cid:3)(cid:70)(cid:68)(cid:81)(cid:70)(cid:72)(cid:85)(cid:85)(cid:72)(cid:86)(cid:17)(cid:68)(cid:68)(cid:70)(cid:85)(cid:77)(cid:82)(cid:88)(cid:85)(cid:81)(cid:68)(cid:79)(cid:86)(cid:17)(cid:82)(cid:85)(cid:74)(cid:3)(cid:82)(cid:81)(cid:3)(cid:36)(cid:83)(cid:85)(cid:76)(cid:79)(cid:3)(cid:24)(cid:15)(cid:3)(cid:21)(cid:19)(cid:20)(cid:27)(cid:17)(cid:3)(cid:139)(cid:3)(cid:20)(cid:28)(cid:28)(cid:21)(cid:3)(cid:3)
`
`Genentech 2131
`Celltrion v. Genentech
`IPR2017-01122
`
`

`

`ANTIBODY TARGETING OF HER-2/neu
`
`% ID/Gm "3'I-4D5/% ID/Gm /751-DA-4-4 in tumor or (organ)
`% 1D/Gm ”"1-4D5/% ID/GM ?751-DA4-4 in blood
`
`were radiolabeled with 1 mCi Na'*'I (Amersham) by the Iodo-Gen
`method. Mice received i.p. injections of 10 ug of ''I-4D5 (specific
`activity, 1.8 wCi/ug) and 10 ug of '5I-DA4-4 (specific activity, 1.4 wCi/
`ug). At 6, 18, 24, 48, 72, and 120 h postinjection the animals were
`sacrificed, and their tumors and normal organswere harvested, washed,
`weighed, and analyzed for both '*'I and '‘I activity. The i.p. route was
`chosen for these studies because preliminary experiments demonstrated
`virtually identical muMABbiodistributionsafter i.p. and i.v. injections
`but less mouse-to-mouse variability with the i.p. route, presumably
`because of occasional extravasationsafter tail vein injections. Results
`were expressedas the percentage injected dose of radioactivity per gram
`of tissue. Data were corrected for radioactive decay and spillover from
`the ''I to the '5I channel. Groupsoffive mice were utilized to generate
`each data point, and their mean values were used to construct biodis-
`tribution curves for tumors and normal organs. The area under the
`bloodactivity versus time curves were calculated assuming a model with
`first-order absorption and elimination. Tumor:organ ratios of radioac-
`tivity and localization indices were also determined. Localization in-
`dices were calculated from theratio of specific:irrelevant antibody taken
`up by tumor(or organ) and normalized for simultaneous blood levels:
`
`Flow Cytometry. The specificity of binding of muMABs 7C2 and
`4D5 to the HER-2/neu gene product was assessed by indirect immu-
`nofluorescence. Untransfected 3T3 cells do not express the HER-2/
`neu gene producton their surface and were used as negative controls.
`3T3cells transfected with the HER-2/neu oncogene and SKBR3cells
`express high surface densitities of the p185 protein and were used as
`positive cell lines. Cells (5 x 10°) of each type were incubated with
`saturating concentrations of muMABs4D5,7C2, or DA4-4 for 30 min
`on ice, washed three times, incubated with a 1:20 dilution of a fluores-
`ceinated, affinity-purified, goat anti-mouse immunoglobulin reagent
`(TAGO,Inc., Burlingame, CA) for 30 min, washed three times, and
`then fixed in 1% paraformaldehyde. Cells were analyzed on a FACSII
`cell sorter (Becton Dickinson, Inc., Sunnyvale, CA).
`Cellular Radioimmunoassay. muMABs 7C2 and 4D5 were labeled
`with Na'] (Amersham, Arlington Heights,
`IL) by the Iodo-Gen
`methodas previously described (18). Briefly, 100 ug of antibody were
`added to 0.5 mCi of Na’*‘I in a glass tube coated with 10 ug Iodo-Gen
`(Pierce, Rockford, IL) for 10 min at room temperature. Free Na'”*I
`was removed by chromatography on a PD-10 column (Pharmacia,
`Piscataway, NJ), and eluted fractions were pooled and stored at 4°C.
`The immunoreactivities of '*51-7C2 and '*51-4D5 using NIH3T3 HER-
`2/neu cells were 84% and 79%, respectively, by linear extrapolation to
`binding at infinite antigen excess (19) (data not shown). The avidities
`of '51-7C2 and '*5I-4D5 as determined by Scatchard analysis were 4.48
`Potassium iodide was added to the drinking water of mice 72 h prior
`x 10° L/M and 1.55 x 10° L/M,respectively (data not shown).
`to injecting radiolabeled antibody and was continued for 2 weeks in
`NIH3T3 HER-2/neu cells were washed with cold serum-free RPMI
`order to block thyroid uptake of free iodine.
`1640, pelleted by centrifugation, and cooled on ice for 45 min.
`'**I-
`Autoradiography. To assess the homogeneity of radioactivity deliv-
`muMaABswerethen added to cell pellets in a ratio of 0.1 ug protein
`ered to tumorcells at a microscopic level, s.c. nodules were excised
`(200,000 cpm)/10° cells and incubated for 1 h. Cells were washed twice
`from 15 mice 18hafter i.p. injection of 10 ug (15-20 Ci) of radioio-
`with cold RPMI 1640, plated in microtiter wells (1 < 10° cells/well),
`dinated antibodies and processed for autoradiography. Excised tumors
`and warmed to 37°C in a humidified CO, incubator. After 0, 1, 4, 10,
`were bisected, embedded in OCT compound(Miles,Inc., Elkhart, IN)
`and 24 h the cultures were assayed for surface membrane-bound,
`and frozen in a dry ice-ethanol bath. Full-thickness 6-um cryosections
`intracellular, and supernatantradioactivity ina Beckman Gamma5500
`were cut, fixed in 2% glutaraldehyde and 2% paraformaldehydein 0.1
`counter (Palo Alto, CA) as previously described (20). Cell surface
`M cacodylate (pH 7.4), dehydrated in graded ethanol, and air dried.
`radioactivity was determined by elution of antibody from the cell
`'3!1-4D5(or '51-DA4-4) was detected by dipping slides in Kodak NTB-
`membranebya brief (5-min) exposure to a low-pH buffer (pH 1-2).
`2 nuclear emulsion (International Biotechnologies, Inc., New Haven,
`The cells were subsequently pelleted by centrifugation at 300 x g and
`CT), exposing for 1 week at 4°C, developing in Dektol (Kodak),fixing,
`removed from the microtiter wells with cotton swabs to determine
`and staining. A Nikon Microphot microscope was used to enumerate
`intracellular cpm. Culture supernatants (0.2 ml) were treated with 0.6
`silver grains and perform photomicrography.
`ml 25% TCAto precipitate protein-bound '*I released from the cell
`Radioimmunotherapy and Radioimmunoscintigraphy. For therapy ex-
`surface. This was separated from TCA-soluble supernatantradioactivity
`periments, muMABs4D5 and DA4-4 (0.6-1.0 mg) were radioiodinated
`by centrifugation, and both fractions were assayed in a gammacounter.
`with Na'?'I (6-10 mCi) to specific activities of 7.2-9.3 uCi/pg. Follow-
`Immunoelectron Microscopy. NIH3T3 HER-2/neucells were grown
`ing PD-10 column chromatography, >98% of the '*'I in the resulting
`to confluence in 96-well flat-bottomed plates and then incubated with
`radioimmunoconjugates was protein bound, as demonstrated by cellu-
`muMAB7C2 (64 ug/ml) for 45 min at 4°C. The cells were washed
`lose polyacetate electrophoresis. Groups of 4-7 tumor-bearing mice
`twice with cold media, and then a 1:2 dilution of a horseradish perox-
`each received injections of 400 yCi (range, 392-432 uCi) of '"I-
`idase-conjugated, monovalent, Fab’ goat anti-mouse immunoglobulin
`muMaABsin 0.6 ml PBS in Experiment 1 (45 »g/mouse) and 700 pCi
`antiserum was addedfor an additional 45 min. The plates were washed
`(range, 667-705 uCi) in Experiment 2 (100 ug/mouse). Additional
`again and incubated at 37°C for 0, 15, 30, or 240 min and fixed in 2%
`control groups received either unlabeled muMAB 4D5 (45 ng/mouse
`glutaraldehyde and 2% paraformaldehydein 0.1 mM cacodylate (pH 7.4).
`in Experiment 1; 100 ug/mouse in Experiment 2) or PBS. Tumors
`Cells were then reacted for 15 min with 3,3’-diaminobenzidine (Sigma,
`were measured twice weekly in 3 dimensions with a precision caliper,
`St. Louis, MO)at 0.5 mg/mlin 0.05 m Tris buffer, pH 7.6, containing
`and the mean volumes were plotted versus time to generate growth
`0.0009% hydrogen peroxide. After two washes in 0.1 mM cacodylate,
`curves. The percentage increase in tumorsize was calculated as
`cells were postfixed in 1% osmium tetroxide and dehydrated in graded
`
`ethanol. Cell layers were then carefully processed into Epon 812, and
`V.-— Vo
`blocks were sectioned en face or in cross-section and examined in a
`Vo
`Philips 201 transmission electron microscope operated at 60 kV. Con-
`trol experiments demonstrated no detectable binding of isotype-
`where V, is the mean tumor volume on day x and Vis the mean tumor
`matchedirrelevant antibodies DA4-4 and UPC10 to 3T3/HER-2/neu
`volume onthe day of treatment.
`or SKBR3cells or of anti-HER-2/neu antibodies 7C2 or 4D5 to
`At 0, 24, 48, 72, 144, and 216 h the mice were anesthetized and
`untransfected 3T3cells by this immunoperoxidase technique.
`imaged for 10 min with a 400T General Electric gamma camera
`Antibody Biodistributions.
`Immunodeficient 4-6-week-old male
`equipped with a high-energy collimator. The camera was peaked for
`BALB/c x C57/BI beige/nude mice (Life Sciences, St. Petersburg, FL)
`''T using a symmetric window of 38 keV. The activity within each
`were used for all in vivo experiments, since preliminary studies dem-
`mouse image was determined, and meanvalues were used to construct
`onstrated a higher tumor implantation rate (100% versus 80%) and
`whole-body time-activity curves for '3'I-4D5 and '"I-DA4-4. Tumors
`greater synchrony of tumor growth than that observed with standard
`were outlined as regions of interest with a dedicated ADAC DPS-3300
`nude mice (data not shown). Animalsreceiveds.c. flank injectionsof 1
`computer, and the intraregional activity was measured in order to
`x 10° NIH3T3 HER-2/neu cells. Palpable tumors (24-280 mm:?; mean,
`generate tumortime-activity curves. Data were corrected for radioactive
`60 mm?*) developed after 10 days. For biodistribution experiments,
`decay by serially imaging an '°'I standard. All animals were given
`muMAB4DSandisotype-matched control muaMAB DA4-4 (300 xg)
`potassium iodide as described above.
`1917
`
`% increase =
`
`<x 100
`
`(cid:82)(cid:81)(cid:3)(cid:36)(cid:83)(cid:85)(cid:76)(cid:79)(cid:3)(cid:24)(cid:15)(cid:3)(cid:21)(cid:19)(cid:20)(cid:27)(cid:17)(cid:3)(cid:139)(cid:3)(cid:20)(cid:28)(cid:28)(cid:21)(cid:3)(cid:36)(cid:80)(cid:72)(cid:85)(cid:76)(cid:70)(cid:68)(cid:81)(cid:3)(cid:36)(cid:86)(cid:86)(cid:82)(cid:70)(cid:76)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:73)(cid:82)(cid:85)(cid:3)(cid:38)(cid:68)(cid:81)(cid:70)(cid:72)(cid:85)(cid:3)(cid:53)(cid:72)(cid:86)(cid:72)(cid:68)(cid:85)(cid:70)(cid:75)(cid:17)(cid:3)
`(cid:70)(cid:68)(cid:81)(cid:70)(cid:72)(cid:85)(cid:85)(cid:72)(cid:86)(cid:17)(cid:68)(cid:68)(cid:70)(cid:85)(cid:77)(cid:82)(cid:88)(cid:85)(cid:81)(cid:68)(cid:79)(cid:86)(cid:17)(cid:82)(cid:85)(cid:74)
`(cid:39)(cid:82)(cid:90)(cid:81)(cid:79)(cid:82)(cid:68)(cid:71)(cid:72)(cid:71)(cid:3)(cid:73)(cid:85)(cid:82)(cid:80)(cid:3)
`Downloadedfrom cancerres.aacrjournals.org on April 5, 2018. © 1992 American Association for Cancer Research.
`
`

`

`RESULTS
`
`Antibody Specificity. Indirect immunofluorescence with flow
`cytometry demonstrated intense, specific binding of the 4D5
`and 7C2 antibodiesto cell lines known to express high surface
`antigen densities of the p185 HER-2/neu gene product (3T3/
`HER-2/neu cells, SKBR3 and SKOV3)butnosignificant bind-
`ing to cell lines lacking oncoprotein expression (e.g., untrans-
`fected 3T3 cells). Fig. 1 shows typical results from one offive
`experiments performed (using 3T3/HER-2/neucells).
`Cellular Radioimmunoassays.Internalization and catabolism
`of '75]-4D5 and '*5I-7C2 by NIH3T3 HER-2/neu, SKBR3, and
`SKOV3cells were evaluated in vitro using a cellular radio-
`immunoassay. Pulse-labeled cultures were assayed after 0, 1, 4,
`10, and 24 h of incubation at 37°C for surface membrane-
`bound,intracellular, and supernatantradioactivity. Three sep-
`arate experiments yielded similar results. There was a steady
`loss of surface cpm from NIH3T3 HER-2/neu cells, with a
`reciprocal increase in supernatant cpm for both 4D5 and 7C2
`(Fig. 2, a and 5). Intracellular cpm peaked at 22% after 4 h for
`
`Number
`
`Cell
`
`Fluorescence Intensity (Log1o)
`Fig. 1. Fluorescein-activated cell sorter analysis of binding of anti-HER-2/neu
`antibodies to untransfected NIH 3T3cells and to 3T3 cells transfected with the
`HER-2/neu oncogene. ----- , 4DS5 on untransfected cells; - - - -, 7C2 on
`
`untransfected cells; ——-, 4D5 on HER-2/neu transfected cells; -----» 7C2 on
`transfected cells;
`, control antibody UPC10 ontransfected cells.
`
`
`jpernatant
`C
`-—— Surface CPM
`—*— Intracetiular CPM
`
`
`a
`
`100
`
`80
`
`s
`a
`oo
`°°
`& 0
`R
`20
`
`0
`
`0
`
`4
`
`16
`12
`#8
`Time (hours)
`
`20
`
`24
`
`b
`
`100
`
`80
`
`=
`oe
`O 60
`
`& 0
`x
`20
`
`0
`
`o
`
`4
`
`16
`#12
`8
`Time (hours)
`
`20
`
`24
`
`%TotalCPM
`
`%TotalCPM 12)
`
`o
`
`4s
`
`12
`8
`16
`Time (hours)
`
`20
`
`24
`
`o
`
`4
`
`16
`8
`Time (hours)
`
`2000
`
`24
`
`Fig. 2. Internalization and catabolism of antibody by NIH3T3 HER-2/neu
`cells. Cells were pulse labeled with '7°1-4D5(a, c) or '*51-7C2 (6, d) and incubated
`at 37°C for 0, 1, 4, 10, or 24 h before assaying for surface membrane-bound,
`intracellular, and supernatant cpm (a, 5). Culture supernatants were subsequently
`precipitated with 25% TCAtodistinguishintact '**I-muMABs (TCA-precipitable)
`from low-molecular-weight catabolites (TCA-soluble) (c, @).
`
`(cid:82)(cid:81)(cid:3)(cid:36)(cid:83)(cid:85)(cid:76)(cid:79)(cid:3)(cid:24)(cid:15)(cid:3)(cid:21)(cid:19)(cid:20)(cid:27)(cid:17)(cid:3)(cid:139)(cid:3)(cid:20)(cid:28)(cid:28)(cid:21)(cid:3)(cid:36)(cid:80)(cid:72)(cid:85)(cid:76)(cid:70)(cid:68)(cid:81)(cid:3)(cid:36)(cid:86)(cid:86)(cid:82)(cid:70)(cid:76)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:73)(cid:82)(cid:85)(cid:3)(cid:38)(cid:68)(cid:81)(cid:70)(cid:72)(cid:85)(cid:3)(cid:53)(cid:72)(cid:86)(cid:72)(cid:68)(cid:85)(cid:70)(cid:75)(cid:17)(cid:3)
`(cid:70)(cid:68)(cid:81)(cid:70)(cid:72)(cid:85)(cid:85)(cid:72)(cid:86)(cid:17)(cid:68)(cid:68)(cid:70)(cid:85)(cid:77)(cid:82)(cid:88)(cid:85)(cid:81)(cid:68)(cid:79)(cid:86)(cid:17)(cid:82)(cid:85)(cid:74)
`(cid:39)(cid:82)(cid:90)(cid:81)(cid:79)(cid:82)(cid:68)(cid:71)(cid:72)(cid:71)(cid:3)(cid:73)(cid:85)(cid:82)(cid:80)(cid:3)
`Downloadedfrom cancerres.aacrjournals.org on April 5, 2018. © 1992 American Association for Cancer Research.
`
`ANTIBODY TARGETING OF HER-2/neu
`
`100
`
`80
`
`%TotalCPM
`
`—@— Surface CPM
`—O— Supernatant CPM
`
`—k— Intracellular CPM
`
`0
`
`4
`
`16
`12
`8
`Time (hours)
`
`20
`
`24
`
`%TotalCPM
`
`s nwn —@-— TCA Sol. CPM
`---O-=" TCA Precip. CPM
`
`
`
`0
`
`4
`
`#12
`8
`16
`Time (hours)
`
`20
`
`24
`
`Fig. 3. Internalization and catabolism of antibody by SKBR3cells. Cells were
`pulse labeled with '75I-4D5 and incubated at 37°C for 0, 1, 4, 10, or 24 h before
`assaying for surface membrane-bound,intracellular, and supernatant cpm (a).
`Culture supernatants were subsequently precipitated with 25% TCAto distinguish
`intact '?51-4D5 (TCA-precipitable) from low-molecular-weight catabolites (TCA-
`soluble) (5).
`
`4D5 and 17% after 1 h for 7C2. After 24 h the percentage of
`total radioactivity remaining cell associated (i.e., cell surface
`plus intracellular cpm) was 46% and 56% for 4D5 and 7C2,
`respectively. Conversely, after 24 h 54% and 44% of total
`culture cpm were found within the supernatant for 4D5 and
`7C2, respectively. Supernatants were treated with 25% TCAto
`determine the proportion of supernatant radioactivity contrib-
`uted by intact antibody (TCA precipitable) and by small-molec-
`ular-weight metabolites (TCA soluble). TCA-soluble cpm pro-
`gressively increased during the 24-h incubation period for both
`4DS5and 7C2, reaching peak values of 44% and 39% oftotal
`culture cpm, respectively (Fig. 2, c and d). Hence, approxi-
`mately 44% of '5I-4DS5 and 39% of '75I-7C2 wereinternalized,
`degraded, and exocytosed by the tumorcells in 24 h. The same
`pattern of internalization and catabolism was observed when
`these antibodies were incubated with human breast (SKBR3;
`Fig. 3) and ovarian (SKOV3; not shown) carcinomacelllines,
`which also overexpress the HER-2/neu oncoprotein.
`Immunoelectron Microscopy. The endocytic pathway of
`muMAB7C2 was studied by immunoelectron microscopy in
`vitro. NIH3T3 HER-2/neu cells were incubated with saturating
`concentrations of 7C2 for 30 min at 4°C, washedthree times,
`and then incubated for 30 min with a monovalent, horseradish
`peroxidase-conjugated Fab’ goat anti-mouse immunoglobulin
`antiserum. Cells were washed again with cold buffer and then
`warmedto 37°C for 0, 15, 30, or 240 min before processing for
`electron microscopy as described in “Materials and Methods.”
`At 4°C anti-HER-2/neu antibodies remained circumferentially
`distributed on the surface ofcells (Fig. 4a), but when cells were
`warmedto 37°C endocytosis rapidly ensued. Within 15-30 min
`of incubation at 37°C,
`large numbers of peroxidase-labeled
`1918
`
`

`

`time points evaluated. The tu-
`the normal organs at all
`mor:normal organ ratios of radioactivity ranged from 5:1 to
`10:1 and were most favorable 24-72 h postinjection (Table 1).
`The superiorlocalization of '3'I-4D5 within tumors wasaresult
`of specific binding to the p185 oncoprotein, as illustrated in
`Fig. 55. Up to 8-fold more anti-HER-2/neu muMABthan the
`irrelevant antibody '5I-DA4-4 accumulated in the tumors.
`However,the percentageinjected dose of radioactivity per gram
`of tissue of '*'I-4D5 decreased precipitously from 25% at 24h
`to 5% at 120 h postinjection. The area underthe blood activity
`versus time curve was determined for both conjugates and
`revealed that '*5I-DA4-4 remainedin circulation approximately
`3 times longer than '*'I-4D5 (data not shown). Localization
`indices for the tumor and normalorgansare presented in Table
`
`ANTIBODY TARGETING OF HER-2/neu
`
`
`0
`
`Tumor
`Blood
`Kidney
`Liver
`Muscle
`Spleen
`LungStomach
`Thyroid
`
`25
`
`75
`50
`Time (Hrs)
`
`%1D/Gm
`%1D/Gm
`
`Fig. 4. Immunoelectron microscopy documenting endocytosis of anti-HER2/
`neu antibodies by NIH3T3 cells transfected with the HER-2/new oncogene.
`Indirect immunoperoxidase cytochemistry was used to study the internalization
`of muMAB7C2as described in “Materials and Methods.” a, muMAB 7C2 was
`densely distributed on the surface of NIH3T3 HER-2/neucells at time 0. Within
`15-30 min of incubation at 37°C large numbers of peroxidase-labeled “coated
`pits” (5, arrows), “coated vesicles,” and uncoated endocytic vesicles (c) were
`detectable. Large numbers of peroxidase-labeled dense body lysosomes became
`evident between 30 and 240 minofincubation (d). Bars, 1 um (a, c, d) or 0.1 um
`(5).
`
`0
`
`25
`
`100
`
`125
`
`75
`50
`Time (Hrs)
`Fig. 5. a, biodistribution of '?'l-4DS5 in beige/nude mice bearing HER-2/neu-
`expressing tumors. Groups offive mice bearing s.c. NIH3T3 HER-2/neu tumor
`grafts received simultaneousinjections of 10 yg of '°"I-4D5 (18 »Ci) and 10 ug
`of '51-DA4-4 (14 wCi). At 6, 24, 48, 72, and 120 h postinjection the animals were
`sacrificed, and their tumors and normal organs were harvested, weighed, and
`assayed for '*'I and '**I activity. The biodistribution curves for '?"I-4D5 within
`tumor, blood, and normal tissues are shown. 5, comparative localization of '3"I-
`4D5and '*51-DA4-4 within tumors as a function of time.
`
`“coated pits,” “coated vesicles,” and uncoated endocyticvesicles
`were detectable (Fig. 4, b and c). Large numbers of peroxidase-
`labeled dense body lysosomes becameevident between 30 and
`240 min ofincubation (Fig. 4d). Similar results were observed
`with other anti-HER-2/neu antibodies and other p185-express-
`ing cell lines (e.g., SKBR3; data not shown).
`In Vivo Biodistribution. The biodistribution of muMABs 4D5
`and 7C2 were evaluated in beige/nude mice bearing s.c.
`NIH3T3 HER-2/neu tumor grafts. Animals received simulta-
`neousi.p. injections of 10 ug each of '!I-4D5 and '751-DA4-4.
`120
`72
`48
`24
`6
`Organ
`At 6, 18, 24, 48, 72, and 120 h postinjection the mice were
`1.21
`1.58
`1.35
`1.47
`0.43
`Blood
`sacrificed, and their tumors and organs were harvested, washed,
`5.49
`10.40
`9.20
`10.56
`2.60
`Kidney
`5.50
`714
`6.36
`6.42
`1.54
`Liver
`weighed, and assayed for '?'I and '*5] activity. Specific localiza-
`4.01
`8.29
`6.77
`7.85
`2.15
`Spleen
`tion of antibody to tumors was documented in four separate
`4.21
`5.55
`5.25
`6.37
`1.74
`Lung
`6.79
`20.78
`20.65
`17.95
`3.77
`Stomach
`experiments. A representative study is shown in Fig. 5a. The
`Thyroid 6.93 4.12 10.81 8.86 9.69
`
`
`
`
`
`concentrationof '>'I-4D5 within tumor exceeded that in any of
`1919
`
`Table 1 Tumor:normalorgan ratios for '*"I-4D5
`The tumor:normalorgan ratios of activity for '*"I-4D5 were calculated at 6,
`24, 48, 72, and 120 h after the injection of radioimmunoconjugate into beige/
`nude mice bearing 3T3/HER-2/neu tumors. Groups of five mice were used to
`generate mean valuesfor each time point. Data were normalized for tissue weight
`and corrected for radioactive decay.
`
`Time(h)
`
`(cid:82)(cid:81)(cid:3)(cid:36)(cid:83)(cid:85)(cid:76)(cid:79)(cid:3)(cid:24)(cid:15)(cid:3)(cid:21)(cid:19)(cid:20)(cid:27)(cid:17)(cid:3)(cid:139)(cid:3)(cid:20)(cid:28)(cid:28)(cid:21)(cid:3)(cid:36)(cid:80)(cid:72)(cid:85)(cid:76)(cid:70)(cid:68)(cid:81)(cid:3)(cid:36)(cid:86)(cid:86)(cid:82)(cid:70)(cid:76)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:73)(cid:82)(cid:85)(cid:3)(cid:38)(cid:68)(cid:81)(cid:70)(cid:72)(cid:85)(cid:3)(cid:53)(cid:72)(cid:86)(cid:72)(cid:68)(cid:85)(cid:70)(cid:75)(cid:17)(cid:3)
`(cid:70)(cid:68)(cid:81)(cid:70)(cid:72)(cid:85)(cid:85)(cid:72)(cid:86)(cid:17)(cid:68)(cid:68)(cid:70)(cid:85)(cid:77)(cid:82)(cid:88)(cid:85)(cid:81)(cid:68)(cid:79)(cid:86)(cid:17)(cid:82)(cid:85)(cid:74)
`(cid:39)(cid:82)(cid:90)(cid:81)(cid:79)(cid:82)(cid:68)(cid:71)(cid:72)(cid:71)(cid:3)(cid:73)(cid:85)(cid:82)(cid:80)(cid:3)
`Downloadedfrom cancerres.aacrjournals.org on April 5, 2018. © 1992 American Association for Cancer Research.
`
`

`

`ANTIBODY TARGETING OF HER-2/neu
`
`Table 2 Localization indices for '*'I-4D5
`Thelocalization indices for '*'I-4D5 were calculated 6, 24, 48, 72, and 120 h
`after the simultaneousinjection of '*"J-4D5 and '5I-DA4-4 into tumor-bearing
`beige/nude mice, as described in “Materials and Methods.” Groupsoffive mice
`were used to generate mean values for each time point. Data were corrected for
`radioactive decay andspillover from the '*'I to the '?°I channel.
`Time(h)
`
`Organ
`Tumor
`Kidney
`Liver
`Spleen
`Lung
`Stomach
`Thyroid
`
`6
`2.17
`0.96
`1.50
`1.07
`1.15
`0.75
`0.98
`
`24
`6.60
`1.09
`1.46
`1.10
`1.09
`1.59
`1.23
`
`48
`4.14
`1.08
`1.27
`0.97
`1.05
`2.08
`1.12
`
`72
`5.31
`1.06
`1.22
`0.97
`1.07
`2.16
`1.09
`
`120
`3.50
`1.48
`1.23
`2.02
`1.14
`2.51
`1.22
`
`8 weeks. Noneof the 10 mice mice treated with unlabeled 4D5
`or PBSsurvived for 8 weeks.
`Serial gammacamera imaging was performedas described in
`“Materials and Methods”to assess the abilities of '*'I-4D5 and
`'31]-DA4-4 to image tumorgrafts (Fig. 9). Excellent imaging
`of HER-2/neu-expressing tumors was reliably achieved using
`1311-4D5, with optimal resolution being obtained between 8 and
`72 h after injection of '*'I-4D5. Specific localization of radio-
`activity to tumors was not observed using '*'I-DA4-4, but mice
`retained radioactivity longer when receiving injections of this
`antibody. The biological t,,2 of '?'I-DA4-4 was 6.5 days, ap-
`proximately twice that of '?'I-4D5 (3.3 days; Fig. 10a). Tumor
`time-activity curves for '*'I-4D5 and '*'I-DA4-4 were generated
`by serially measuring the activity within a region of interest
`constructed around the tumor image(Fig. 10). As anticipated,
`a higher peak activity within the tumor was achieved with the
`anti-HER-2/neu conjugate. However, this antibody appeared
`to be cleared from the tumor more rapidly than the irrelevant
`conjugate. The protracted clearance of the irrelevant antibody
`from tumorsites mostlikely resulted from the lack of specific
`endocytosis and catabolism of '*'I-DA4-4 by tumorcells, as
`well as from the increased blood flow to rapidly growing tumors
`in mice given the control reagent.
`
`2. Specific uptake of '?'I-4D5 within tumors wasseen asearly
`as 6 h postinjection (localization index = 2.2) and reached a
`maximum valueof 6.6 at 24 h. The biodistribution of muaMAB
`7C2 paralleled that of 4D5, with up to 28% injected dose of
`radioactivity per gram of tumor accumulating within tumorsat
`36 h, and tumor:normalorgan radioactivity ratios of 5:1 to 30:1
`(data not shown).
`Autoradiography of Tumor Nodules. To assess the heteroge-
`neity of antibody distribution within tumor nodules, tumors
`from 15 mice in 3 biodistribution experiments were processed
`for autoradiography 18 h after injection of '*'I-4D5, as de-
`scribed in “Materials and Methods.” A heterogeneousdistri-
`bution of autoradiographicsilver grains was observed in tumors,
`with the heaviest grain densities occurring in perivascular lo-
`cations(Fig.6).
`Radioimmunotherapy and Imaging. In order to assess the
`therapeutic efficacy of radioiodinated anti-HER-2/neu mu-
`MABsin our animal model, beige/nude mice bearing estab-
`lished NIH3T3 HER-2/neu tumorgrafts receivedi.p. injections
`of 400 uCi of '3'I-4D5 (45 ug/mouse). Groups of control mice
`received either 400 Ci '"I-DA4-4, unlabeled 4D5 (45 yug/
`mouse), or PBS. Tumor volumes were measured twice weekly,
`and the mean values were plotted versus time to construct
`growth curves. Nosignificant difference in tumor growth was
`observed between animals treated with unlabeled 4D5 and PBS
`(Fig. 7). However, mice treated with '*'I-4D5 showed marked
`tumor growth retardation. Animals given '*'I-DA4-4 also ex-
`perienced tumor growth delays, although the degree of inhibi-
`tion was significantly less pronounced than in the '3"I-4D5
`treated group (Fig. 7). The different regimens were also com-
`pared by calculating the percentage increase in tumorsize at
`various days posttreatment,relative to the initial tumor volume.
`Table 3 demonstrates that '*'I-4D5 was 20-fold more effective
`than '*'J-DA4-4 in retarding tumor growth 24 daysafter anti-
`bodyinjection and was 75-fold moreefficacious than unlabeled
`4DS. Although the effect of '*'I-4D5 was striking,
`tumors
`eventually progressed in all animals. Tumor regrowth, which
`generally occurred 3 weeks after therapy, was not due to the
`selection of an antigen-negative cell clone, since grafts contin-
`ued to overexpress the HER-2/neu protein when evaluated by
`immunohistochemistry (data not shown). Rather, treatment
`failure most
`likely resulted from the inability to deliver a
`sufficiently lethal radiation dose to the tumor. Nofatal toxici-
`ties were observed in mice treated with 400 uCi of '*"I-4D5 or
`'311-DA4-4; all deaths at this dose level were due to tumor
`progression.
`In an attempt to achieve curative tumor ablations, we re-
`peated the radioimmunotherapyexperimentusing a higher '*"I
`activity (700 rather than 400 »Ci/mouse; Fig. 8). This higher
`dose of '3'I-4D5 caused tumor growth retardation similar in
`magnitude to that seen in mice given 400 Ci of the conjugate
`(Fig. 7) and did not prevent eventual tumor progression (Fig.
`8). Furthermore, increasing the radiation dose of the control
`reagent, '>"I-DA4-4, to 700 uCi increased the nonspecific total
`body irradiation in recipient mice dramatically, resulting in
`significant tumorregressions in this control group (Fig. 8). At
`the higher dose level, fatal hematological toxicity was observed
`in two offive recipients of the '*'I-DA4-4 reagent but in none
`of the four mice treated with '*!I-4D5. Hematological parame-
`ters reached nadir values 14 days posttherapy and returned to
`normal by day 21 in surviving mice (data not shown). Two of
`“O. W.Press, J. F. Eary, C. C. Badger, P. J. Martin, F. R. Appelbaum,R.
`four mice treated with 700 »Ci '*'I-4D5 survived >8 weeks,
`Levy, R. Miller, S. Brown, W. B. Nelp, K. A. Krohn, D. Fisher, K. B. De Santes,
`B. Porter, P. Kidd, E. D. Thomas,and I. D. Bernstein, unpublished results.
`whereas only oneoffive mice treated with '*'I-DA4-4 survived
`1920
`
`DISCUSSION
`
`Breast and ovarian adenocarcinomas accountfor 36% ofall
`adult female malignancies and cause over 50,000 deaths/year
`in the United States alone (21). Although considerable progress
`has been madein treating these diseases, approximately 30%
`of breast cancer patients and 60% of ovarian cancer patients
`cannot be cured with current therapeutic approaches. Patients
`whose tumors amplify and overexpress the HER-2/neu gene
`have an especially poor prognosis (7) and constitute a group
`for whom new treatment strategies are needed. One novel
`approach for such patients might involve therapy with immu-
`noconjugates targeting the HER-2/neu gene product. We have
`recently tested an analogous approach in 14 patients with
`relapsed non-Hodgkin’s lymphomausingradioiodinated mono-
`clonal antibodies directed against B-lymphocyte differentiation
`antigens. Preliminary results have been encouraging; all 14
`lymphomapatients have had objective responses, including 11
`complete responses, with remission durations ranging from 4
`to 38+ months (22).*
`The HER-2/neu oncoprotein is an attractive target for anti-
`body-mediated therapy for several reasons. Overexpression oc-
`
`(cid:82)(cid:81)(cid:3)(cid:36)(cid:83)(cid:85)(cid:76)(cid:79)(cid:3)(cid:24)(cid:15)(cid:3)(cid:21)(cid:19)(cid:20)(cid:27)(cid:17)(cid:3)(cid:139)(cid:3)(cid:20)(cid:28)(cid:28)(cid:21)(cid:3)(cid:36)(cid:80)(cid:72)(cid:85)(cid:76)(cid:70)(cid:68)(cid:81)(cid:3)(cid:36)(cid:86)(cid:86)(cid:82)(cid:70)(cid:76)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:73)(cid:82)(cid:85)(cid:3)(cid:38)(cid:68)(cid:81)(cid:70)(cid:72)(cid:85)(cid:3)(cid:53)(cid:72)(cid:86)(cid:72)(cid:68)(cid:85)(cid:70)(cid:75)(cid:17)(cid:3)
`(cid:70)(cid:68)(cid:81)(cid:70)(cid:72)(cid:85)(cid:85)(cid:72)(cid:86)(cid:17)(cid:68)(cid:68)(cid:70)(cid:85)(cid:77)(cid:82)(cid:88)(cid:85)(cid:81)(cid:68)(cid:79)(cid:86)(cid:17)(cid:82)(cid:85)(cid:74)
`(cid:39)(cid:82)(cid:90)(cid:81)(cid:79)(cid:82)(cid:68)(cid:71)(cid:72)(cid:71)(cid:3)(cid:73)(cid:85)(cid:82)(cid:80)(cid:3)
`Downloadedfrom cancerres.aacrjournals.org on April 5, 2018. © 1992 American Association for Cancer Research.
`
`

`

`ANTIBODY TARGETING OF HER-2/neu
`
`@ 1-131 4D5
`© 1-131 DA4-4
`4 Unlabeled 4D5
`A No Treatment
`
`0
`
`10
`
`20
`
`30
`
`Day
`
`14
`oO 2
`E
`~ 10
`g 8
`6
`4
`
`b
`
`5 20
`
`oS
`
`Fig. 7. Radioimmunotherapy of NIH3T3 HER-2/neu tumorgrafts. Groups of
`five to seven beige/nude mice bearing well-established s.c. tumors received injec-
`tions of 400 uCi '"I-4D5, 400 uCi '"I-DA4-4, unlabeled 4D5, or PBS. Tumor
`volumes were measured twice weekly, and the mean values were plotted versus
`time to generate growth curves.
`
`imally tolerated doses of radioimmunoconjugate were used (700
`uCi). At least two mechanisms may havecontributed to our
`inability to permanently eradicate tumors in this model system.
`First, the inhomogeneousdeposition of '*'I-4D5 within tumors
`demonstrated by autoradiography may have resulted in the
`sublethal irradiation of tumor cells distant from capillaries,
`allowing subsequent regrowth of tumors. Second, rapid intra-
`tumoral antibody catabolism may have compromisedtheeffi-
`cacy of this approach by diminishing the retention of '*'I
`targeted to tumors by the 4DSantibody. Cellular radioimmuno-
`assays and immunoelectron microscopy demonstrated prompt
`internalization of '*'I-4D5 after binding to cells, followed by
`intracellular routing to lysosomes where degradation and deiod-
`ination occurred, followed by exocytosis of the radiolabel. Sim-
`ilar studies have recently been published by other workers(30).
`In vivo biodistribution studies demonstrated that the anti-HER-
`2/neu conjugate reached a 6-7-fold higher peak concentration
`within tumors than the irrelevant antibody but wasalso cleared
`morerapidly from tumors than the nonbinding, noninternalized
`'311-DA4-4 antibody.
`Several strategies could be attempted to improve radiation
`delivery to HER-2/neu-expressing tumors. A fractionated treat-
`ment schedule might permit delivery of a higher cumulative
`
`curs in approximately one-third of breast and ovarian cancers
`but not on normaladult tissues (23). In addition, antigen density
`appears to be uniform throughout a given tumor, so the anti-
`body could theoretically be distributed to all regions of the
`malignancy (9). Furthermore, excellent concordance has been
`observed between the level of expression within primary and
`metastatic or recurrentlesions (8, 9, 12). Finally, the likelihood
`of developing an antigen-negative cell clone may be reduced in
`this setting, since continued expression of p185 appears to be
`a prerequisite for maintaining the malignant phenotype incells
`transformed by HER-2/neu (14).
`In this report, we have demonstrated the ability of a radio-
`iodinated anti-HER-2/neu muMABtoretard the growth of
`HER-2/neu-expressing tumors implanted in immunocompro-
`mised mice. Several mechanisms maybe responsible for the
`antitumoreffect including down-regulation of p185 expression
`(24) and radiation-induced genetic damage from '*"I (25-27).
`Antigenic modulation of the HER-2/neu protein may deprive
`the cell of an important oncogenic growth signal and increase
`its susceptibility to certain cytokines such as tumor necrosis
`factor a (28). Hudziaket al. (28) and Drebinet al. (15, 29) have
`shown that muMABs4D5and 7C2inhibit the in vitro growth
`of SKBR3 andother tumorcell lines which overexpress p185.
`However, cell growth resumed when the antibody was removed
`from the culture media, suggesting a cytostatic rather than
`cytotoxic effect. Furthermore, coinjection of unmodified anti-
`HER-